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Antibacterial activity of avocado extracts (Persea americana Mill.) against Streptococcus agalactiae



Plants contain numerous constituents and are valuable sources of new biologically active molecules. Avocado (Persea americana Mill.) is cultivated and used as food in most tropical and subtropical countries. Its high nutritional value and biological activities, as antioxidant, antimicrobial and analgesic properties, have been thoroughly investigated. Interest in plant extracts with antimicrobial properties has increased as a result of the indiscriminate use of antibiotics, leading to the emergence of resistant bacterial strains. Among bacterial species with clinical importance to multiple hosts, Streptococcus agalactiae is outstanding, as it can cause infections especially in humans, fish and cattle. The current study aimed to evaluate the antimicrobial activity of two extracts (ethanol and dichloromethane) from avocado seeds, ‘Margarida’ variety, against isolates of S. agalactiae. Extracts were diluted in ethanol / water (1:1) at a concentration of 100 mg/mL. Antimicrobial activity was tested by the disk diffusion method (antibiogram) against isolates of S. agalactiae of human and fish origin.The ethanol extract showed antimicrobial activity only for some isolates of S. agalactiae of human origin. The dichloromethane extract showed activity against all isolates of S. agalactiae of both origins. A comparison of the results obtained with dichloromethane extract from isolates of S. agalactiae of human or fish origin demonstrated the existence of phenotypic variability among isolates from the same host. However, when comparing measurements obtained in each of the groups, they were statistically similar, showing a lack of interpopulation variability. Thus, it can be verified that the resistance profile of isolates of S. agalactiae was independent of host origin and typical of the species
FYTON ISSN 0031 9457 (2016) 85: 218-224
Antibacterial activity of avocado extracts (Persea americana Mill.) against
Streptococcus agalactiae
Actividad antibacteriana de extractos de aguacate (Persea americana Mill.) sobre
Streptococcus agalactiae
Cardoso PF1, JA Scarpassa1, LG Pretto-Giordano2, ES Otaguiri3, SF Yamada-Ogatta3,
G Nakazato3, MRE Perugini4, IC Moreira5, GT Vilas-BÔas1*
Resumen. Las plantas contienen numerosos constituyentes y son
fuentes ricas de nuevas moléculas biológicamente activas. El aguacate
(Persea americana Mill.) es cultivado y utilizado como alimento en la
mayoría de los países tropicales y subtropicales, ya que tiene alto valor
nutricional, y sus actividades biológicas han sido muy investigadas, en-
tre las cuales la actividad antioxidante, analgésica o antimicrobiana. El
interés en extractos vegetales con propiedades antimicrobianas se ha
intensicado como consecuencia de la utilización indiscriminada de
antibióticos, que llevó a la selección de cepas bacterianas resistentes.
Entre las especies bacterianas de relevancia clínica para variados hos-
pederos, se puede destacar la bacteria Streptococcus agalactiae, que pue-
de causar infecciones, principalmente en humanos, peces y ganado. El
objetivo de ese trabajo fue evaluar la actividad antimicrobiana de dos
extractos (etanólico y diclorometanico) de hueso de aguacate variedad
margarita en relación a aislados de S. agalactiae. Los extractos fueron
resuspendidos en etanol/agua en la concentración de 100 mg/mL. La
actividad antibacteriana de los extractos fue comprobada usando el
método de difusión en discos frente a aislados de S. agalactiae de origen
humano y peces. El extracto etanólico presentó actividad antimicrobia-
na solamente para algunos aislados de S. agalactiae de origen humano.
El extracto diclorometanico presentó actividad antimicrobiana para
todos los aislados de S. agalactiae de ambos orígenes. La comparación
de los resultados obtenidos con el extracto diclorometanico enfrente a
los aislados de S. agalactiae de origen humano y peces mostró la exis-
tencia de variabilidad fenotípica entre aislados del mismo hospedero.
Sin embargo, la comparación de las medias obtenidas en cada uno de
los grupos fue estadísticamente semejante, demostrando la ausencia de
variabilidad interpoblacional. De esta manera, se pudo observar que el
perl de resistencia de aislados de S. agalactiae fue independiente del
hospedero de origen y característico de la especie.
Palabras clave: Extractos vegetales; Método de difusión en disco.
Abstract. Plants contain numerous constituents and are valu-
able sources of new biologically active molecules. Avocado (Persea
americana Mill.) is cultivated and used as food in most tropical and
subtropical countries. Its high nutritional value and biological activi-
ties, as antioxidant, antimicrobial and analgesic properties, have been
thoroughly investigated. Interest in plant extracts with antimicro-
bial properties has increased as a result of the indiscriminate use of
antibiotics, leading to the emergence of resistant bacterial strains.
Among bacterial species with clinical importance to multiple hosts,
Streptococcus agalactiae is outstanding, as it can cause infections espe-
cially in humans, sh and cattle. e current study aimed to evaluate
the antimicrobial activity of two extracts (ethanol and dichlorometh-
ane) from avocado seeds, ‘Margarida’ variety, against isolates of S.
agalactiae. Extracts were diluted in ethanol / water (1:1) at a con-
centration of 100 mg/mL. Antimicrobial activity was tested by the
disk diusion method (antibiogram) against isolates of S. agalactiae
of human and sh origin.e ethanol extract showed antimicrobial
activity only for some isolates of S. agalactiae of human origin. e
dichloromethane extract showed activity against all isolates of S. aga-
lactiae of both origins. A comparison of the results obtained with di-
chloromethane extract from isolates of S. agalactiae of human or sh
origin demonstrated the existence of phenotypic variability among
isolates from the same host. However, when comparing measure-
ments obtained in each of the groups, they were statistically similar,
showing a lack of interpopulation variability. us, it can be veried
that the resistance prole of isolates of S. agalactiae was independent
of host origin and typical of the species.
Keywords: Plant extracts; Disk diusion method.
1 Departamento de Biologia Geral, Centro de Ciências Biológicas, Universidade Estadual de Londrina.
2 Departamento de Medicina Veterinária Preventiva, Centro de Ciências Agrárias, Universidade Estadual de Londrina.
3 Departamento de Microbiologia, Centro de Ciências Biológicas, Universidade Estadual de Londrina.
4 Departamento de Patologia, Análises Clínicas e Toxicológicas, Centro de Ciências da Saúde, Universidade Estadual de Londrina.
5 Universidade Tecnológica Federal do Paraná- Campus Londrina, Brazil.
Address correspondence to: Gislayne Trindade Vilas-BÔas, e-mail:
Received 17.X.2014. Accepted 17.IV.2015.
FYTON ISSN 0031 9457 (2016) 85: 218-224
Avocado extracts against Streptococcus agalactiae
e control of bacterial infections is mostly carried out
with antibiotics. However, the emergence of resistant bacte-
rial strains has become more frequent, leading to the need of
new sources of molecules with antimicrobial activity, which
have been found mainly in microorganisms and plants (Cow-
an, 1999; Mlynarczyk et al., 2010). Natural plant products
have been used since ancient times for medicinal purposes as
they comprise numerous components and valuable sources of
new biologically active molecules (Cowan, 1999; Gupta et al.,
Many plants synthesize antimicrobial secondary metabo-
lites as part of their normal growth and development, often
keeping them in tissues that need protection against micro-
bial attack (Gupta et al., 2004). e antimicrobial activity of
plant extracts may reside in a variety of dierent phytochemi-
cal constituents, namely terpenoids, essential oils, alkaloids,
lectins, polypeptides and polyphenolics and phenolic sub-
stances (simple phenols, phenolic acids, quinones, avones,
avonols and avonoids, tannins and coumarins) (Gonçalves
et al., 2005). e antibacterial activity of these extracts may
be ascribable to the combined eects of the polyphenols ad-
sorption on bacterial membrane, leading to its rupture and
subsequent leakage of cellular content, and the generation of
hydroperoxides (Negi, 2012).
Among plants, avocado (Persea americana Mill), originated
from Central America, presents a high nutritional value and
is cultivated and used as food in most tropical and subtropi-
cal countries. Its peel, fruit and leaves are commonly used in
America, Antilles and Africa for the treatment of various dis-
eases such as menorrhagia, hypertension, stomach pain, bron-
chitis, diarrhea and diabetes (Adeyemi et al., 2002). However,
avocado seeds are usually discarded during consumption or
industrial processes generating residues that could be an eco-
nomical alternative for treatment of some diseases.
e avocado leaf, stem, fruit and peel have biological ac-
tivities scientically proven (Miranda et al., 1997; Adeyemi
et al., 2002; Quing-Yi et al., 2005; Gomez-Flores et al.,
2008; Castro et al., 2010; Rodríguez-Carpena et al., 2011).
Studies with seed demonstrated antioxidant activity and an-
timicrobial activity against Bacillus cereus, Staphylococcus au-
reus, Listeria monocytogenes, Escherichia coli, Pseudomonas spp.
and Yarrowia lipolytica. e Gram-positive bacteria are more
sensitive than Gram-negative bacteria (Rodríguez-Carpena
et al., 2011). Other seed properties already studied are larvi-
cidal (in Aedesaegypti), antifungal (Candida spp., Cryptococ-
cus neoformans and Malassezia pachydermatis) (Leite et al.,
2009) and antimicrobial activities against several species
including S. aureus, Enterococcus faecalis, Salmonella Enteriti-
dis, Citrobacter freundii, Pseudomonas aeruginosa, Salmonella
Typhimurium, Enterobacter aerogenes and Zygosaccharomyces
bailii (Chia & Dykes, 2010).
Phytochemical studies of the avocado seed allowed the
identication of several classes of active compounds such as
avonoids, anthocyanins, condensed tannins, alkaloids and
triterpenoids in methanolic extracts, while sterols and triter-
penes were detected in the hexane extract (Leite et al., 2009).
Several bacterial species are considered of clinical impor-
tance because they cause a number of diseases in various hosts.
Among these, the species Streptococcus agalactiae, a Gram pos-
itive, catalase negative and facultatively anaerobic bacteria is
remarkable.is species can cause infections in cattle, humans
and sh. Furthermore, it can occasionally infect mice, cats,
dogs, camels and frogs (Elliot et al., 1990; Figueiredo, et al.,
2006; Pereira et al., 2010).
Streptococcus agalactiae is one of the most common causes
of perinatal bacterial infections in humans. It is also an op-
portunistic pathogen of the elderly and immunocompromised
people, and may cause pneumonia, meningitis, bacteremia and
skin or soft tissue infections (Gibbs et al., 2004; Nakamura et
al., 2011). Penicillin is the treatment of choice. However, for
patients allergic to β-lactam, erythromycin or clindamycin are
prescribed. Mammal isolates are preferably β-hemolytic, but
some nonhemolytic have been isolated, and are usually culti-
vated at 37 °C (Evans et al., 2002; Gibbs et al., 2004).
Besides humans, S. agalactiae can infect freshwater and
marine sh, either in sh farming or free in the environment
(Figueiredo et al., 2006). It is considered the main pathogenic
bacteria of dierent species of sh with high mortality. Natu-
rally or experimentally infected sh exhibit symptoms, such
as unilateral or bilateral exophthalmia, corneal opacity, er-
ratic swimming, changes in skin color, skin lesions and ascites
(Figueiredo et al., 2006; Pretto-Giordano et al., 2010a). Fish
isolates of S. agalactiae are usually not hemolytic and are culti-
vated at 30°C, which may indicate phenotypic adaptations to
host (Elliot et al., 1990; Evans et al., 2002; Castro et al., 2008).
S. agalactiae isolates of human source present resistance
to tetracycline, clindamycin, erythromycin, chloramphenicol,
rifampicin, noroxacin, levooxacin, ciprooxacin, moxioxa-
cin (Borger et al., 2005; Correa et al., 2011; Nakamura et al.,
2011; Ki et al, 2012; Usein et al., 2012). Fish isolates may be
resistant to nalidixic acid, gentamicin, neomycin, noroxacin
and streptomycin (Evans et al., 2002; Figueiredo et al., 2006).
e susceptibility of S. agalactiae to natural extracts was
analyzed in dierent works. According to Cueva et al. (2012),
S. agalactiae presented sensitivity to phenolic compounds iso-
lated from wine, epicatechin and gallic acid, and was not sen-
sitive to oenological extracts. It was also sensitive to extracts
of wild mushrooms (Alves et al., 2012) and to the essential
oil from eight eucalyptus species (Elassi et al., 2012). Leaf
extracts of Calyptranthes clusiifolia, Croton oribundus, Heiste-
ria silvianii, Merremia tomentosa and Zanthoxylum riedelianum
also inhibited S. agalactiae growth (Castro et al., 2008).
us, the aim of this study was to investigate the antibacte-
rial activity of avocado (P. americana Mill) seed extracts against
FYTON ISSN 0031 9457 (2016) 85: 218-224
Cardoso PF et al., FYTON 85 (2016)
S. agalactiae isolates of human and sh origin. erefore, com-
parison of intra- and inter-population variability of resistance
proles was evaluated and indicated the potential therapeutic
use of the avocado seed against this bacterial species.
Plant extracts. In order to obtain seed extracts of avocado
(P. americana Mill., ‘Margarida’ variety), the seed was initially
separated from the pulp, fragmented, dried and ground into
powder. e seed powder was then exposed to a maceration
process for a period of seven days, either using ethyl alcohol as
solvent, resulting in an extract termed “ethanolic extract”, or
using dichloromethane as solvent, yielding an extract termed
“dichloromethane extract”. Subsequently, the extracts were l-
tered and concentrated in a rotary evaporator. Procedures of
maceration, ltration and concentration were repeated once
more with both extracts. In order to measure the eciency of
extraction, the obtained extracts were weighed and the ratio
between 500g of the initial seed powder and the nal weight
calculated. Extracts were dissolved in ethanol / water (1:1),
stored at room temperature and protected from light until use.
Bacterial strains and culture conditions. e evalua-
tion of 29 S. agalactiae isolates recovered from vaginal-rectal
swabs and urine of female patients at the University Hos-
pital of Universidade Estadual de Londrina (originally used
by Otaguiri et al., 2013) was performed. ese isolates had
already been characterized for bacterial species conrmation
by phenotypic tests (CAMP, KEA, NaCl, hippurate, baci-
tracin, trimethoprim-sulfamethoxazole, Gram staining and
catalase). ese isolates were incubated for 24 hours at 37 °C
in Muller Hinton blood agar plates (supplemented with 5%
sheep blood).
e assessment of 26 isolates of S. agalactiae obtained from
the Nile tilapia (Oreochromis niloticus) with bacterial infection
symptoms was conducted. e isolates were collected from
dierent organs, including eyes, brain, liver, heart, blood, vis-
ceral uid and kidney sh collected at sh farming properties
located in the northern region of Paraná state and northwest
region of São Paulo state, Brazil.e strains had been previ-
ously identied as S. agalactiae by Gram stain and biochemical
assays, and conrmed by more accurate tests, such as API 20
Strep Microtest (BioMerieux) and SlidexStrepto-kit (BioM-
erieux) (Pretto-Giordano et al., 2010b). ese isolates were
incubated for 48 hours at 30 °C in Muller Hinton blood agar
Antibiograms. e antibacterial activity of avocado seed
extracts against S. agalactiae was evaluated by the Disc dif-
fusion method on Muller Hinton blood agar plates, as rec-
ommended by CLSI (Clinical Laboratory Standard Institute,
2010). For this purpose, bacteria concentration followed the
0.5 MacFarland scale, yielding an inoculum density of ap-
proximately 108 CFU/mL (Ostrosky et al., 2008) which was
homogeneously distributed over the plates using sterile swabs.
Discs of 6 mm diameter (Laborclin, Brazil) received the
application of 10 µL of 100 mg/mL ethanol or dichloro-
methane extracts. Additionally, other discs received 10 µL of
solvents and were used as a negative control. All discs were
kept for an hour under a laminar ow for solvent evaporation
(Ostrosky et al., 2008).
Biplates were used, forming a duplicate of each isolate per
plate. ree discs were placed on each plate side: control, etha-
nol and dichloromethane extract. In other words, two disks
were tested for each extract per strain. Samples of human
source were incubated at 37 °C for 24 hours. Strains of sh
origin were maintained at 30 °C for 48 hours. At the end of
this time, the inhibition zone diameter was measured.
Statistical analysis. e susceptibility test results were an-
alyzed using the Analysis of Variance (ANOVA) followed by
the Tukey test or the Mann-Whitney test for interpopulation
analysis, at 95% condence level. Tests were performed with
the GraphPad InStat program, version 3.05.
After the extraction procedures, the nal weight of extracts
was 12.76 g for the ethanolic and 7.48g for the dichlorometh-
ane extract. Bacterial inhibition by extracts was evaluated
visually by measuring the inhibition zone diameters around
disks (disk diameter included) recorded in millimeters. e
antimicrobial activity was classied into three levels: low ac-
tivity (inhibition zone ≤12 mm), moderate activity (inhibition
zone between 12 and 20 mm) and strong activity (inhibition
zone ≥20 mm), following the criteria adopted in other studies
with plant extracts (Rota et al., 2008; Fei et al, 2011).
Antibiogram results of S. agalactiae isolates are shown in
Table 1 and exemplied in Figures 1 and 2. Both human and
sh isolates showed statistical variability in intra-group analy-
sis, exhibiting an inhibition zone between 7 mm e 13 mm
for human isolates, and between 9 mm and 12 mm for sh
For the intergroup analysis, the average of inhibition zones
obtained for each group (human and sh origin) was com-
pared. Statistical analysis for ethanolic extract could not be
performed, since inhibition zones on plates with sh isolates
were not observed. However, dierences in susceptibility be-
tween strains of human and sh could be observed, given that
the rst show some susceptible isolates, while in the latter, no
susceptible isolates were found (Table 1). e antimicrobial
activity of the ethanolic extract, when present, was considered
weak, with an inhibition zone between 7 mm and 9.5 mm.
e mean ± standard deviation of the inhibition zonediam-
eter for the isolates of human origin observed for the dichlo-
FYTON ISSN 0031 9457 (2016) 85: 218-224
Avocado extracts against Streptococcus agalactiae
Table 1. Antimicrobial activity of avocado seed extracts against S. agalactiae strains.
Tabla 1. Actividad antimicrobiana de extractos de semilla de aguacate contra cepas de S. agalactiae.
(human source)
Inhibition zone diameter (mm)
(sh source)
Inhibition zone diameter (mm)
Ethanolic extract Dichloromethane
extract Ethanolic extract Dichloromethane
Mean ± Standard
Deviation Mean ± Standard
Deviation Mean ± Standard
Deviation Mean ± Standard
67.75 ± 0.35 10.75 ± 0.35 15 0.00 ± 0.00 10.75 ± 0.35
97.75 ± 0.35 11.75 ± 0.35 16 0.00 ± 0.00 10.50 ± 0.00
10 4.00 ± 5.66 11.00 ± 0.00 18 0.00 ± 0.00 10.75 ± 0.35
11 8.75 ± 1.06 11.00 ± 0.71 19 0.00 ± 0.00 11.00 ± 0.00c
12 0.00 ± 0.00 11.00 ± 0.00 23 0.00 ± 0.00 11.00 ± 0.00c
13 0.00 ± 0.00 11.25 ± 0.35 25 0.00 ± 0.00 10.75 ± 0.35
14 0.00 ± 0.00 12.75 ± 0.35 26 0.00 ± 0.00 11.25 ± 0.35 c.e
21 0.00 ± 0.00 11.25 ± 1.06 29 0.00 ± 0.00 10.50 ± 0.00
24 0.00 ± 0.00 10.75 ± 0.35 30 0.00 ± 0.00 10.75 ± 0.35
25 0.00 ± 0.00 11.25 ± 0.35 34 0.00 ± 0.00 10.50 ± 0.00
26 0.00 ± 0.00 10.25 ± 0.35 a 35 0.00 ± 0.00 9.75 ± 0.35 d
27 0.00 ± 0.00 10.50 ± 0.00 a 37 0.00 ± 0.00 9.75 ± 0.35 d
28 0.00 ± 0.00 10.25 ± 0.35 a 38 0.00 ± 0.00 11.00 ± 0.00 c
29 0.00 ± 0.00 10.50 ± 0.00 a 39 0.00 ± 0.00 10.25 ± 0.35
33 4.25 ± 6.01 10.50 ± 0.71 a 40 0.00 ± 0.00 9.25 ± 0.35d
37 7.25 ± 0.35 11.00 ± 0.00 42 0.00 ± 0.00 11.75 ± 0.35 c.e
42 3.50 ± 4.95 11.25 ± 0.35 44 0.00 ± 0.00 10.75 ± 0.35
43 0.00 ± 0.00 11.75 ± 1.06 45 0.00 ± 0.00 11.25 ± 0.35 c.e
49 0.00 ± 0.00 10.50 ± 0.00 a 46 0.00 ± 0.00 10.75 ± 0.35
50 0.00 ± 0.00 11.00 ± 0.71 47 0.00 ± 0.00 10.50 ± 0.00
52 0.00 ± 0.00 12.00 ± 0.00 48 0.00 ± 0.00 9.50 ± 0.00 d
54 0.00 ± 0.00 10.25 ± 0.35 a 50 0.00 ± 0.00 10.50 ± 0.71
56 0.00 ± 0.00 9.75 ± 0.35 a.b 52 0.00 ± 0.00 11.00 ± 0.71 c
59 0.00 ± 0.00 11.00 ± 0.71 53 0.00 ± 0.00 10.25 ± 0.35
60 0.00 ± 0.00 10.25 ± 0.35 a 55 0.00 ± 0.00 10.75 ± 1.06
61 3.50 ± 4.95 10.25 ± 0.35 56 0.00 ± 0.00 11.00 ± 0.00 c
62 0.00 ± 0.00 11.00 ± 0.00
70 0.00 ± 0.00 11.00 ± 0.00
96 0.00 ± 0.00 11.25 ± 1.06
a: statistically diers from strain 14; b: statistically diers from strain 52; c: statistically diers from strain 40; d: statistically diers from
strain 42; e: statistically diers from strain 48 (P<0.05).
a: diere estadísticamente de la cepa 14; b: diere estadísticamente de la cepa 52; c: diere estadísticamente de la cepa 40; d: diere estadísticamente de la
cepa 42; e: diere estadísticamente de la cepa 48 (P<0,05).
FYTON ISSN 0031 9457 (2016) 85: 218-224
Cardoso PF et al., FYTON 85 (2016)
Fig. 1. Antibiogram of S. agalactiae isolates of human source: a) strain 6, b) strain 14 and c) strain 25. Disc 1: ethanol/water control;
Disc 2: ethanolic extract (100 mg/mL); Disc 3: dichloromethane extract (100 mg/mL).
Fig. 1. Antibiograma de aislados humanos de S. agalactiae: a) cepa 6, b) cepa 14 y c) cepa 25. Disco 1: control etanol/agua; Disco 2: extracto
etanólico (100 mg/mL); Disco 3: extracto diclorometanico (100 mg/mL).
Fig. 2. Antibiogram of S. agalactiae isolates of fish source: (a) strain 26, (b) strain 34 and (c) strain 55. Disc 1: ethanol/water control; Disc
2: ethanolic extract (100 mg/mL); Disc 3: dichloromethane extract (100 mg/mL).
Fig. 2. Antibiograma de aislados de peces de S. agalactiae: (a) cepa 26, (b) cepa 34 y (c) cepa 55. Disco 1: control etanol/agua; Disco 2:
extracto etanólico (100 mg/mL); Disco 3: extracto diclorometanico (100 mg/mL).
romethane extract was 10.93 ± 0.62 mm. On the other hand,
sh isolates presented a mean ± standard deviation of 10.61 ±
0.56 mm. e comparison between means was not statistically
signicant, with p = 0.0897. e dichloromethane extract an-
tibacterial activity was considered weak.
Plant extracts are sources of a variety of biotechnology
products. erefore, countless studies have been conducted
in order to evaluate characteristics of these extracts, which
can be used for the treatment of diseases, due to their an-
timicrobial, antifungal, analgesic, anti-inammatory and
antitumor activities (Miranda et al., 1997; Adeyemi et al.,
2002; Qing-Yi et al., 2005; Leite et al., 2009; Rodríguez-
Carpena et al., 2011). Among the commonly evaluated
properties, the antimicrobial activity has received special
attention, and numerous studies have been conducted, in-
cluding dierent avocado extracts (Gomez-Flores et al.,
2008; Castro et al., 2010; Chia & Dykes, 2010; Rodríguez-
Carpena et al., 2011).
However, although widely used, there are not yet any
standardization methods to analyze the antimicrobial activ-
ity of extracts of natural products (Ostrosky et al., 2008). e
Disk diusion test is indicated by the FDA (Food and Drug
Administration / USA) and established as standard by the
FYTON ISSN 0031 9457 (2016) 85: 218-224
Avocado extracts against Streptococcus agalactiae
CLSI (Clinical Laboratory Standard Institute / USA, 2010),
and, therefore, was the method chosen to conduct this study.
Several S. agalactiae isolates of human and sh origin were
used in this work, aiming to comprise dierent phenotypic
variations found in isolates from each of the two sources, as
well as verify what kind of host presents isolates more suscep-
tible to the evaluated extracts.
Human source isolates used in this study have already been
analyzed for capsular type, genotyping by MLVA, antibiotics
susceptibility and genetic virulence determinants. e results
suggest that even commensal S. agalactiae isolates have high
potential for virulence and are susceptible to most antimi-
crobial agents tested (penicillin, ampicillin, vancomycin, etc.)
(Otaguiri et al., 2013). However, they presented moderate re-
sistance to erythromycin (19%) and clindamycin (13%) which
demands the search for new treatment alternatives, especially
for patients allergic to β-lactam antibiotics.
e dierence in eciency of the two extracts can be ex-
plained by the dierence in polarity of solvents. During the
extraction process, polarity inuences solubility of the main
active substance, leading to dierence in their chemical com-
position and consequently, in their biological activity (Idris
et al., 2009). e yield of extraction and concentration of the
extract solution can also intervene in the results.
e antimicrobial activity of avocado extracts may be as-
cribable to its chemical composition. Phytochemical screen-
ing highlighted the presence of phenolic compounds in avo-
cado tissues, whose antimicrobial activity is well documented
(Idris et al., 2009; Rodriguez-Carpena et al., 2011).
Avocado seed extracts showed low antimicrobial activity
against of S. agalactiae isolates. is can probably be overcome
by increasing extract concentration. e results indicate that
the avocado seed is a potential source of antimicrobial sub-
stances and arouses considerable interest in new research with
more puried extracts for the identication of compounds re-
sponsible for the antimicrobial activity.
is work was supported by grants from Coordenação de
Aperfeiçoamento de Pessoal de Nível Superior (CAPES) and
Conselho Nacional de Desenvolvimento Cientíco e Tec-
nológico (CNPq).
Adeyemi, O.O., S.O.Okpo & O.O. Ogunti (2002). Analgesic and
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... However, compared to avocado flesh, its waste has been commonly utilized in various types of research on antioxidant capacity and antibacterial activity; for example, avocado seeds have been proven to be a significant source of phenolic compounds with antioxidant characteristics. Avocado seeds have a high concentration of antibacterial compounds, which has sparked interest in the investigation of extracting antibacterial components from avocado seeds [24]. Meanwhile, the avocado's lipid fraction is high in phytochemicals and antioxidants [25]. ...
... Egbuonu et al. also demonstrated the antibacterial activity of avocado seed extracts as illustrated by the diameter of the inhibition zone against Proteus mirabilis (23 ± 0.14 mm), Staphylococcus aureus (16 ± 0.04 mm), and Pseudomonas aeruginosa (15 ± 0.11 mm), despite being lower than that of ciprofloxacin antibiotics [26]. Besides, this extract also shows higher antifungal activity against Aspergillus niger than the ketoconazole [24], with higher total phenolic content and antioxidant capacity [27]. ...
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Although avocado is a superfood rich in phytochemicals with high antioxidant activities, studies on the antibacterial properties of its pulp are limited, except for seed and peel portions. In this study, three types of solvent (acetone, methanol, and diethyl ether) were used to obtain the extracts from “Maluma” avocado pulp powder prepared by infrared drying. The extracts were analyzed for total polyphenols, phytopigments (total chlorophylls and carotenoids), antioxidant activities (ferric-reducing antioxidant power (FRAP), 2,2-Diphenyl-1-picrylhydrazyl (DPPH), and 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assays), and antibacterial activities against seven pathogens (Shigella sonnei ATCC 9290, Escherichia coli ATCC 8739, Salmonella typhi ATCC 6539, Vibrio parahaemolyticus ATCC 17802, Proteus mirabilis ATCC 25933, Staphylococcus aureus ATCC 6538, and Bacillus cereus ATCC 11778). The results showed that the acetone solvent could extract the highest polyphenols and chlorophylls with the highest antioxidant activity in terms of ABTS and DPPH assays. In contrast, diethyl ether exhibited the most significant content of carotenoids and FRAP values. However, the methanol extract was the best solvent, exerting the strongest antibacterial and meaningful antioxidant activities. For the bacterial activities, Gram-positive pathogens (Bacillus cereus and Staphylococcus aureus) were inhibited more efficiently by avocado extracts than Gram-negative bacteria. Therefore, the extracts from avocado powder showed great potential for applications in food processing and preservation, pharmaceuticals, and cosmetics.
... El extracto que generó mayores mortalidades en mosquitos fue el extracto de acetato de etilo, mientras que la menor actividad fue del extracto cloroformico. Cardoso et al. (2016) evaluaron la actividad antimicrobiana de dos extractos (etanolico y diclorometanico) de la SA en aislados de Streptococcus agalactiae. Los extractos fueron resuspendidos en una mezcla de etanol/agua a una concentración de 100 mg/mL. ...
... Por lo que en éste trabajo concluyen que este sub-producto del aguacate constituye un material útil para el crecimiento de E. coli, y otros microorganismos de interés biotecnológico. Sin embargo, se recomienda considerar el amplio espectro antimicrobiano que se describió previamente en este trabajo, ya que uno de los microorganismos que muestra resistencia al efecto inhibitorio de la semilla, es justamente E. coli (Cardoso et al., 2016). ...
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Due to the various nutrients and vitamins that avocado presents, it is considered the healthiest fruit in the world. Of this fruit, only its pulp is used, generating tons of by-products in the form of shell and seed. The avocado seed (AS) represent up to 18% of the total weight of the fruit, even though it is a good source of protein and antioxidant compounds, is generally discarded, becoming a source of contamination. Therefore, a review of biotechnological applications of this by-product of avocado is shown, where its composition, antioxidant capacity, therapeutic and antimicrobial properties are considered, as well as its use in the removal of toxic compounds and for the production of biofuels, emphasizing its toxicological risks due their anti-nutrients. The biotechnological applications and patents described in this work demonstrate the economic potential of the AS.
... Thus, it has been suggested that avocado (seed and peel) could be considered as a promising antimicrobial agent for pathologies produced by bacteria, fungus, and others that should be validated through in vivo studies [46]. In addition, it should be considered that the antibacterial and antifungal effects of avocado extracts may depend on the solvent used for extraction, type of strain, and source of bacteria isolated [2] since it has also been reported that avocado seed extracts showed weak and no inhibition against Streptococcus agalactiae from human and fish sources, respectively [65]. ...
... These leaves and bark extracts contain saponins, tannins, flavonoids, and terpenoids, which are effective against E. coli and Staphylococcus aureus [32]. Further, the fruit contains defensin PaDef, which is potent in killing E. coli and S. aureus [33], and the seed contains a high phenolic compound effective against E. coli, S. aureus, and Streptococcus agalactiae [34]. ...
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Poultry meat consumption is increasing worldwide but the overuse of antimicrobials for prevention and treatment of diseases has increased antimicrobial resistance (AMR), triggering a major public health issue. To restrict AMR emergence, the government supports the optimization of natural products that are safe and easy to obtain with minimal side effects on poultry, humans, and the environment. Various studies have explored the potential of herbs in animal health for their antiviral, antibacterial, antifungal, antiparasitic, immunomodulatory, antioxidant, and body weight gain properties. Therefore, this study reviewed plants with potential application in avian species by summarizing and discussing the mechanisms and prophylactic/therapeutic potential of these compounds and their plant origin extracts.
... Avocado seeds have a potentially effect as antibacterial. [26] Group K-4 was the group given avocado seed extract at a dose of 300 mg/g BW,and K-5 was the group given avocado seed extract at a dose of 600 mg/kg BW. Both groups showed improvement in total leukocytes and their components. ...
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Staphylococcus aureus is often the cause of various diseases and food poisoning in animals and humans. Avocado seeds ( Persea americana , Mill) contain important compounds that have antimicrobial activity. This study aimed to observe the hematological dynamics of mice ( Mus musculus domesticus ) infected with S. aureus and induced by P. americana extract. BALB/c male mice aged 12 weeks were divided into 6 groups of 5 in each group, named K-1, K-2, K-3, K-4, K-5, and K-6. All groups were infected with S. aureus 1x10 ⁸ CFU cell/mL intraperitoneally (IP) on day 0. After the blood sample was taken, then K-1 was given a single dose of tetracyclin 130 mg/kg BW, K-2 was given 130 mg/kb BW oferythromycin, K-3 was given aquabidest (placebo), K-4 was given P. americana extract 300 mg/kg BW, K-5 at a dose 600 mg/kg BW and K-6 at a dose 1200 mg/kg BW. The treatment was given for 7 consecutive days, then a second blood sample was taken and analyzed with the VetScan-HM5 analyzer and interpreted. It was concluded that S. aureus infection caused leukopenia and was potentially followed by lymphopenia, neutrophilia, and monocytosis. The occurrence of microcytosis can lead to anemia, which can be categorized as microcytic hypochromic or normocytic normochromic. Administration of P. americana extract at a dose 300 mg/kg BW (K-4) for 7 days after S. aureus infection was found to be effective in improving hematological values in mice back to normal.
... Plant based antimicrobial agents are targets of many scientific researches to fight MRSA. Among these, avocado has been documented to exert a good antimicrobial activity (Cardoso et al. 2016). Avocado, an exotic fruit of family Lauraceae, is classified as a functional food according to American dietetic association (Figueroa et al. 2018). ...
The aim of this study is to estimate the nutritive values, metabolites of Hass and Reed Avocado cultivars and evaluate their antimicrobial and anticancer activities. Hass was rich in water soluble vitamins, iron and calcium while, Reed contains more fat soluble vitamins. Benzaldehyde and butyl phenol derivatives were the major volatile components identified by solid phase extraction in Hass and Reed, respectively. Naringenin and rutin were the major compounds identified in Hass and Reed by HPLC analysis respectively. Hass showed a promising antimicrobial activity, especially, against Methicillin-Resistant S. aureus (MIC = 7.81 μg/mL). Two targets sites were selected to investigate the mechanism of action of Hass, Staphylococcal Enterotoxin-like X and Serine/threonine kinases Proteins (STK). Molecular docking demonstrated high binding affinity of naringenin towards Enterotoxin-like X. However, high levels of rutin in Reed might account for its cytotoxic activity against colorectal adenocarcinoma. Avocado extracts may be used for developing potential antibiotics.
... Several classes of natural compounds have been isolated from P. americana, such as alkanols (sometimes called aliphatic acetogenins or acetogenins of Lauraceae), alkylfurans (avocadofurans), fatty acids, triglycerides, phytosterols, triterpenes, flavonoids, dimers of flavonoids, saccharides, proanthocyanidins, glycosylated abscisic acids, and derivatives from benzoic and cinnamic acids and from phenols (Rodriguez-Saona et al. 1999;1998, b;Ding et al. 2007;Leite et al. 2009;Dabas et al. 2013;Rodríguez-Sánchez et al. 2013;Ragasa et al. 2014). To date, biological studies carried out with extracts and compounds obtained from kernels of P. americana have detected promising antimicrobial activities (Néeman et al. 1970;Leite et al. 2009;Chia and Dykes 2010;Cardoso et al. 2017), antiprotozoal (Abe et al. 2005;Jiménez-Arellanes et al. 2013) and insecticidal effects against pest species of medical (Leite et al. 2009;Adesina et al. 2016), and agricultural (Stein and Klingauf 1990;Santa-Cecília et al. 2010) importance, which provided the hypothesis on their use in the production of a bioinsecticide for the control of whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) biotype B. B. tabaci is an important pest species of polyphagous feeding habit that has caused major economic losses in Tropical America (Gilbertson et al. 2015;Barbosa et al. 2016;Fariña et al. 2019) due to the inefficiency of chemical control, the main method used for its control, especially because of the large number of populations resistant to active ingredients registered (Nauen and Denholm 2005;Naveen et al. 2017;Dângelo et al. 2018;Dângelo et al. 2018). ...
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Fruit processing waste, such as kernels (endocarp + seed) of avocado [Persea americana Mill. (Lauraceae)], could be used as raw material in the preparation of botanical insecticides. In light of this potential, this study assessed the insecticidal action of extracts and fractions from kernels of two avocado cultivars (Breda and Margarida) on Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) biotype B, an important pest species in tropical conditions. Ethanolic and aqueous extracts prepared from kernels of P. americana, regardless of the plant cultivar used, caused promising insecticidal activity to whitefly nymphs. Based on yield in crude extracts [10.32 and 9.85% (w/w), respectively, for cultivars Breda and Margarida], on the bioassay results with crude extracts and on the chemical profiles, the ethanolic extract of kernels of P. americana cv. Breda was chose for the continuation of the study. Thus, the ethanolic extract of kernels of cv. Breda (LC50 = 197.84 ppm and LC90 = 567.19 ppm) was selected and subjected to fractionation by the liquid-liquid partition technique. The hexane and dichloromethane fractions of this extract caused significant mortality of nymphs. The analysis using the ultraviolet (UV) and hydrogen nuclear magnetic resonance (1H NMR) showed the presence of long-chain aliphatic compounds (alkanols or acetogenins of Lauraceae), alkylfurans (or avocadofurans), and unsaturated fatty acids in these fractions, which are possibly related to bioactivity observed in B. tabaci, besides saccharides. The results show that kernels of P. americana are promising sources of compounds with insecticidal action for the control of B. tabaci biotype B, a great opportunity to transform environmental problems into eco-friendly solutions to agriculture.
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Resumen Las enfermedades infecciosas se encuentran entre las primeras causas de muerte a nivel mundial y la situación se agravada por la aparición progresiva de resistencia a las terapias farmacológicas convencionales. La Persea americana (aguacate), posee sustancias activas que regulan la proliferación de algunos microorganismos patógenos. El objetivo de esta investigación fue evaluar la actividad antimicrobiana y concentración mínima inhibitoria de extractos de Persea americana variedad Choquette sobre el crecimiento de S. aureus ATCC 29213 y E. coli ATCC 25922. La presente fue una investigación de tipo experimental en la que se utilizaron extractos de la cáscara, pulpa y semilla a partir de solventes orgánicos. Se determinó la concentración mínima inhibidora (CMI) y bactericida (CMB) de cada extracto utilizando placas de agar Mueller Hinton las cuales fueron inoculadas con la suspensión bacteriana ajustada. La CMI y CMB para la E. coli. Tratada con la cáscara (solvente hexano y el cloroformo) fue de (1/2)1000 mg/ml; la CMI y CMB para el S. aureus (con los solventes cloroformo y acetato de etilo) fue de (1/2)1000 mg/ml, el extracto de la pulpa no presentó actividad antimicrobiana para ambos microorganismos. Los resultados reflejan actividad antimicrobiana en cascara y semilla, por lo que se propone desarrollar nuevas investigaciones orientadas hacia la caracterización de estos compuestos con miras al desarrollo de fármacos antimicrobianos. Abstract Infectious diseases are among the leading causes of death worldwide and the situation is aggravated by the progressive emergence of resistance to conventional drug therapies. The Persea americana (avocado), has active substances that regulate the proliferation of some pathogenic microorganisms. The objective of this research was to evaluate the antimicrobial activity and minimum inhibitory concentration of extracts of Persea americana variety Choquette on the growth of S. aureus ATCC 29213 and E. coli ATCC 25922. The present was an experimental investigation using extracts of the shell, pulp and seed from organic solvents. The minimum inhibitory (MIC) and bactericidal (MIB) concentration of each extract was determined using Mueller Hinton agar plates which were inoculated with the adjusted bacterial suspension. The MIC and CMB for E. coli. Treated with the shell (hexane solvent and chloroform) was (1/2)1000 mg/ml; the MIC and CMB for S. aureus (with the solvents chloroform and ethyl acetate) was (1/2)1000 mg/ml, the pulp extract did not present antimicrobial activity for both microorganisms. The results reflect antimicrobial activity in shell and seed, so it is proposed to develop further research aimed at the characterization of these compounds for the development of antimicrobial drugs.
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The present research focused on evaluating the antibacterial effect and the mechanism of action of partially purified fractions of an extract of Persea americana. Furthermore, both its antioxidant capacity and composition were evaluated. The extract was fractionated by vacuum liquid chromatography. The antimicrobial effect against Staphylococcus aureus (ATCC 6538), Escherichia coli (ATCC 11229), Pseudomonas aeruginosa (ATCC 15442), and Salmonella choleraesuis (ATCC 1070) was analyzed by microdilution and the mechanism of action by the Sytox green method. The antioxidant capacity was determined by DPPH, FRAP, and ABTS techniques and the composition by Rp-HPLC-MS. All fractions showed a concentration-dependent antibacterial effect. Fractions F3, F4, and F5 (1000 µg/mL) showed a better antibacterial effect than the extract against the bacteria mentioned. The F3 fraction showed inhibition of 95.43 ± 3.04% on S. aureus, F4 showed 93.30 ± 0.52% on E. coli, and F5 showed 88.63 ± 1.15% on S. choleraesuis and 86.46 ± 3.20% on P. aeruginosa. The most susceptible strain to the treatment with the extract was S. aureus. Therefore, in this strain, the bacterial membrane damage induced by the extract and fractions was evidenced by light fluorescence microscopy. Furthermore, the extract had better antioxidant action than each fraction. Finally, sinensitin was detected in F3 and cinnamoyl glucose, caffeoyl tartaric acid, and cyanidin 3-O-(6′′-malonyl-3′′-glucosyl-glucoside) were detected in F4; esculin and kaempferide, detected in F5, could be associated with the antibacterial and antioxidant effect.
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Antimicrobial activity of seed extracts of Persia amerciana against Escherichia coli, Klebsiella pneumoniae, Bacillus subtilis, Streptococcus pyogenes, Pseudomonas aeruginosa, Staphylococcus aureus, Corynebacterium ulcerans, Salmonella typhi, Neisseria gonorrhoea and Candida albicans was carried out using the disc diffusion technique. The methanol, ethyl acetate and chloroform extracts demonstrated promising activity against the test organisms. The activity of methanol extract was more pronounced against C. albicans (42mm) while that of petroleum ether extract was the least against E.coli (6mm). However, S. typhi and E. coli were resistant to chloroform and methanol extracts. The activity of the ethyl acetate, chloroform and methanol extracts compared favourably with that of standard antibiotic streptomycin (30μgdics-1). The minimum inhibitory concentration (MIC) showed that methanol and ethyl acetate extracts had the lowest MIC value (10mg/ml) against C. albicans, indicating higher potency. Preliminary phytochemical screening revealed the presence of flavonoids, saponins, tannins, steroids alkaloids and terpenoids. The spectra of antimicrobial activities displayed by the extracts could be attributed to the presence of these phytochemicals and signifies the potential of Persia amerciana as a source of therapeutic agents. This therefore, supports the traditional medicinal use of Persia amerciana and suggests that further studies should be conducted to isolate and identify the active components of the extract.
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RESUMO Este estudo avaliou as atividades antimicrobianas (AA) de extratos hidro-alcoólicos, obtidos de 17 espécies de árvores nativas do Brasil. Para os ensaios de antibiose foi utilizado o método da difusão em ágar, frente a 10 diferentes microrganismos, isolados de inóculos obtidos de focos de infecções clínicas. Dos 170 testes realizados, 25% mostraram alta AA, destacando-se extratos de Bixaorellana, Psidiumguajava e Anacardium occidentale. Excepcional AA foi observada em Mimosa tenuiflora contra Streptococcus pyogenes, Proteus mirabilis, Shigella sonnei, Staphylococcus aureus e Staphylococcus spp. coagulase-negativa, e os extratos de Stryphnodendron adstringens e Eugenia uniflora contra Escherichia coli, Providencia spp., Streptococcus pyogenes, Proteus mirabilis, Shigella sonnei, Staphylococcus aureus e Staphylococcus spp. coagulase-negativa. Ensaios de antibiose com antibióticos comerciais foram realizados contra estas bactérias, com a finalidade de se comparar o potencial de AA de extratos destas árvores.
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Streptococcus agalactiae or Group B Streptococci (GBS) have the ability to access various host sites, which reflects its adaptability to different environments during the course of infection. This adaptation is due to the expression of virulence factors that are involved with survival, invasion and bacterial persistence in the host. This study aimed to characterize GBS isolates from women of reproductive age seen at University Hospital of Londrina, according to capsular typing, genetic relatedness, antimicrobial susceptibility profile and occurrence of virulence determinants. A total of 83 GBS isolates were enrolled in this study. Capsular types Ia (42.2%), II (10.8%), III (14.5%) and V (30.1%) were identified in most GBS. One isolate each was classified as type IX and non-typeable.A total of 15 multiple locus variable number of tandem repeat analysis (MLVA) types were identified among the isolates, seven were singletons and eight were represented by more than four isolates. All isolates were susceptible to penicillin, ampicillin, cefepime, cefotaxime, chloramphenicol, levofloxacin and vancomycin. Resistance to erythromycin and clindamycin was observed in 19.3 and 13.3% of isolates, respectively. All isolates resistant to clindamycin were simultaneously resistant to erythromycin and were distributed in the capsular types III and V. One isolate showed the constitutive macrolide-lincosamide-streptogramin B (cMLSB) phenotype and ten showed the inducible MLSB (iMLSB) phenotype. The mechanism of resistance to erythromycin and clindamycin more prevalent among these isolates was mediated by the gene ermA, alone or in combination with the gene ermB. The isolates displaying resistance only to erythromycin belonged to capsular type Ia, and showed the M phenotype, which was mediated by the mefA/E gene. All isolates harbored the gene hylB and at least one pilus variant, PI-1, PI-2a or PI-2b. Although cylE was observed in all GBS, four isolates were classified as gamma-hemolytic and carotenoid pigment non-producers. Our results indicate the potential virulence of commensal GBS isolates, reinforcing the need for continued screening for this bacterium to prevent infections. The distribution of capsular and pili antigens, and MLVA profiles was also identified, which may contribute to the development of new strategies for the prevention and treatment of GBS infection.
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RESUMO Avaliar in vitro a atividade antibacteriana de extratos hidroalcoólicos obtidos a partir das folhas da Eugenia uniflora L. (Pitangueira), da casca do caule da Persea americana Mill. (Abacateiro), e das cascas dos frutos do Citrus limon L. (Limoeiro) e Sicana odorífera L. (Cruá) frente a Lactobacillus casei (ATCC 7469). A atividade antibacteriana foi determinada a partir da Concentração Inibitória Mínima (CIM) de crescimento bacteriano. Os extratos foram testados por meio do método de difusão em ágar sangue, pela técnica dos poços. Não houve formação de halos de inibição de crescimento do microrganismo avaliado para o extrato do Citrus limon L. e Sicana odorifera L.. Porém, observou-se atividade antibacteriana para Eugenia uniflora L., sendo verificada CIM de 6,25mg/mL. O extrato da Persea americana L. apresentou CIM de 25mg/mL. Diante dos resultados expostos, pode-se concluir que, dentre os produtos naturais avaliados, apenas a Eugenia uniflora L e Persea americana L apresentaram atividade antibacteriana sobre o Lactobacillus casei. ABSTRACT It was aimed to evaluate, in vitro, the antibacterial activity of hydroalcoholics extracts obtained from the leaves of Eugenia uniflora L. (Pitangueira), the peel of the stem of Persea Americana Mill. (Abacateiro), and the peel of the fruits of Citrus limon L. (Limoeiro) and Sicana odorífera L. (Cruá) against Lactobacillus casei (ATCC 7469). The antibacterial action was determined by the Minimum Inhibitory Concentration (MIC) of bacterial growth. Hydroalcoholics extracts were tested by the diffusion method using blood agar, through wells technique. There was no formation of halos of inhibition of the bacterial growth for Citrus limon L. and Sicana odorifera hydroalcoholics extracts. However, it was verified antibacterial activity for Eugenia uniflora L., which showed a MIC of 6,25mg/mL. The Persea americana L. extract had a CIM of 25mg/mL. Among the natural products evaluated only Eugenia uniflora L and Persea americana L showed antibacterial action against Lactobacillus casei.
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The aim of this work was to evaluate the antibacterial activity of Brazilian plants extracts against fish pathogenic bacteria. Forty six methanolic extracts were screened to identify their antibacterial properties against Streptococcus agalactiae, Flavobacterium columnare and Aeromonas hydrophila. Thirty one extracts showed antibacterial activity.
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OBJETIVOS: verificar a ocorrência de colonização por Streptococcus agalactiae em gestantes e avaliar a suscetibilidade das amostras isoladas aos antimicrobianos. MÉTODOS: foram avaliadas 167 grávidas entre a 32ª e a 41ª semana de gestação, independente da presença ou não de fatores de risco, atendidas no ambulatório de pré-natal entre fevereiro de 2003 e fevereiro de 2004. O material vaginal/anal, colhido com um único swab, foi inoculado em caldo Todd-Hewitt acrescido de ácido nalidíxico (15 µg/mL) e gentamicina (8 µg/mL), com posterior subcultura no meio de ágar sangue. A identificação foi feita por meio da avaliação da morfologia e tipo de hemólise das colônias no meio de ágar sangue, teste da catalase, teste de cAMP e testes sorológicos. A avaliação da suscetibilidade aos antimicrobianos foi realizada pelos testes de difusão e de diluição em ágar. A análise estatística foi realizada por meio do teste de c2; valores de p<0,05 foram considerados significativos. RESULTADOS: a freqüência de colonização foi de 19,2%, sem diferenças significativas com relação à idade, número de gestações, ocorrência de abortos e presença ou ausência de diabete melito (p>0,05). Todas as 32 amostras isoladas foram sensíveis a penicilina, cefotaxima, ofloxacina, cloranfenicol, vancomicina e meropenem. A resistência a eritromicina e clindamicina foi detectada em 9,4 e 6,2% das amostras, respectivamente. CONCLUSÕES: a incidência relativamente elevada (19,2%) de colonização por S. agalactiae entre as gestantes avaliadas e o isolamento de amostras resistentes, especialmente aos antimicrobianos recomendados nos casos de alergia à penicilina, enfatizam a importância de detectar esta colonização no final da gravidez, associada à avaliação da suscetibilidade aos antimicrobianos, para uma prevenção eficaz da infecção neonatal.
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The pathogenesis of a Streptococcus agalactiae was evaluated in a three-period experiment. Two groups of 40 fishes were intraperitoneally (i.p.) challenged in each experimental period with different infective doses of the pathogen. Doses varied from 1.0 x 106 to 1.5 x 108 CFU/fish. One group of 40 tilapia i.p. injected with tryptic soy broth (TSB) was used as a control group in each period. Mortalities varied from 67.5% in group 8 (infective dose 1.0 x 106 CFU/fish) to 90.0% in group 1 (infective dose 1.5 x 108 CFU/fish). Significant differences in mortalities were found only between group 8 and each of the other groups, except group 5 (infective dose 6.0 x 106 CFU/fish; mortality 75.0%). The highest mortality coefficients were observed in days 1-2 after inoculation (accumulated mortality 44.4%), and a second peak of mortality occurred at days 6-7. Challenged fishes from all the groups showed alterations in behaviour and similar clinical signs. These were anorexia, lethargy, erratic swimming, exophthalmia and ascites. Macroscopically, skin hemorrhage, splenomegaly, hepatomegaly with organ paleness and visceral adherences were observed. S. agalactiae was re-isolated from all the fishes from the experimental groups submitted to bacteriological examination. The illness observed in tilapia naturally infected with S. agalactiae was experimentally reproduced in this study, and the clinical signs produced were similar to those reported from the natural infections.
The aim of this study was to evaluate the antimicrobial efficacy of selected plant essential oil (EO) combinations against four food-related microorganisms. Ten EOs were initially screened against Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Saccharomyces cerevisiae using agar disk diffusion and broth dilution methods. The highest efficacy against all the tested strains was shown when testing the oregano EO. EOs of basil and bergamot were active against the Gram-positive bacteria (S. aureus and B. subtilis), while perilla EO strongly inhibited the growth of yeast (S. cerevisiae). The chemical components of selected EOs were also analyzed by GC/MS. Phenols and terpenes were the major antimicrobial compounds in oregano and basil EOs. The dominant active components of bergamot EO were alcohols, esters and terpenes. For perilla EO, the major active constituents were mainly ketones. The checkerboard method was then used to investigate the antimicrobial efficacy of EO combinations by means of the fractional inhibitory concentration index (FICI). Based on an overall consideration of antimicrobial activity, organoleptic impact and cost, four EO combinations were selected and their MIC values were listed as follows: oregano–basil (0.313–0.313μl/ml) for E. coli, basil–bergamot (0.313–0.156μl/ml) for S. aureus, oregano–bergamot (0.313–0.313μl/ml) for B. subtilis and oregano–perilla (0.313–0.156μl/ml) for S. cerevisiae. Furthermore, the mechanisms of the antimicrobial action of EO combinations to the tested organisms were studied by the electronic microscopy observations of the cells and the measurement of the release of cell constituents. The electron micrographs of damaged cells and the significant increase of the cell constituents' release demonstrated that all EO combinations affected the cell membrane integrity.
The present study describes the volatile profile and antimicrobial activity of Thymus vulgaris (thymol chemotype), Thymus zygis subsp. gracilis (thymol and two linalool chemotypes) and Thymus hyemalis Lange (thymol, thymol/linalool and carvacrol chemotypes) essential oils extracted from seven plants cultivated in Murcia (Spain). Antimicrobial activities of the oils were evaluated for control of growth and survival of 10 pathogenic microorganisms.Gas chromatography–mass spectrometry analysis allowed for the identification of between 42 and 51 compounds as main volatile constituents of each essential oil analyzed. Results presented here may suggest that the essential oils from T. hyemalis (thymol) followed by T. hyemalis (carvacrol), T. zygis (thymol) and T. vulgaris possesses antimicrobial properties, and are a potential source of antimicrobial ingredients for the food industry.