ArticlePDF Available

Antibacterial activity of Thymus vulgaris essential oil alone and in combination with cefotaxime against blaESBL producing multidrug resistant Enterobacteriaceae isolates

Taylor & Francis
Natural Product Research
Authors:
  • Misitano & Stracuzzi S.p,a,

Abstract and Figures

The aim was to evaluate the susceptibility of bla ESBL producing Enterobacteriaceae to Slovakian Thymus vulgaris essential oil (TVEO) alone and in combination with cefotaxime (CTX). TVEO composition was determined by gas chromatograph-mass spectrometer (GC/MS). Susceptibility to 21 antibiotics was determined by disc diffusion assay. Genes characterization for resistance to β-lactams was accomplished by polymerase chain reaction (PCR). The antibacterial activity was investigated by standard methods. The synergistic interaction was determined by checkerboard test. Thymol (34.5%), p-cymene (22.27%) and linalool (5.35%) were the major components present in the TVEO. The identified strains were multi-drug resistant (MDR). TVEO showed high activity against all MDR strains, including bla ESBL producing isolates, with inhibition zones and MIC values in the range of 24-40 mm/10μL and 2.87-11.5 μg/mL, respectively. TVEO in combination with CTX showed a synergistic action against bla SHV-12 producing Escherichia coli (FICI 0.28) and an additive effect vs ESBL producing Enterobacter cloacae (FICI 0.987).
Content may be subject to copyright.
Full Terms & Conditions of access and use can be found at
http://www.tandfonline.com/action/journalInformation?journalCode=gnpl20
Natural Product Research
Formerly Natural Product Letters
ISSN: 1478-6419 (Print) 1478-6427 (Online) Journal homepage: http://www.tandfonline.com/loi/gnpl20
Antibacterial activity of Thymus vulgaris essential
oil alone and in combination with cefotaxime
against blaESBL producing multidrug resistant
Enterobacteriaceae isolates
Qada Benameur, Teresa Gervasi, Vito Pellizzeri, Mária Pľuchtová, Hassiba
Tali-Maama, Farida Assaous, Badia Guettou, Kheira Rahal, Daniela Gruľová,
Giacomo Dugo, Andreana Marino & Meriem-Hind Ben-Mahdi
To cite this article: Qada Benameur, Teresa Gervasi, Vito Pellizzeri, Mária Pľuchtová, Hassiba
Tali-Maama, Farida Assaous, Badia Guettou, Kheira Rahal, Daniela Gruľová, Giacomo Dugo,
Andreana Marino & Meriem-Hind Ben-Mahdi (2018): Antibacterial activity of Thymus vulgaris
essential oil alone and in combination with cefotaxime against blaESBL producing multidrug resistant
Enterobacteriaceae isolates, Natural Product Research, DOI: 10.1080/14786419.2018.1466124
To link to this article: https://doi.org/10.1080/14786419.2018.1466124
View supplementary material
Published online: 04 May 2018.
Submit your article to this journal
View related articles
View Crossmark data
NATURAL PRODUCT RESEARCH, 2018
https://doi.org/10.1080/14786419.2018.1466124
Antibacterial activity of Thymus vulgaris essential oil alone
and in combination with cefotaxime against blaESBL producing
multidrug resistant Enterobacteriaceae isolates
QadaBenameura,b, TeresaGervasic, VitoPellizzeric, MáriaPľuchtovád,
HassibaTali-Maamae, FaridaAssaouse, BadiaGuettoue, KheiraRahale, DanielaGruľovád,
GiacomoDugoc,f, AndreanaMarinog and Meriem-HindBen-Mahdib,h
aFaculty of Natural Sciences and Life, Nursing Department, University of Abdelhamid Ibn Badis of Mostaganem,
Mostaganem, Algeria; bLaboratoire de Recherche «Santé et Production Animale», Ecole Nationale
Supérieure Vétérinaire d’El-Harrach, Algiers, Algeria; cDepartment of Biomedical and Dental Sciences and
Morphofunctional Imaging, University of Messina, Messina, Italy; dFaculty of Humanities and Natural Sciences,
Department of Ecology, University of Prešov, Prešov, Slovakia; eLaboratoire de Bactériologie Médicale, Institut
Pasteur d’Algérie, Algiers, Algeria; fScience4Life, Spin Off Company, University of Messina, Messina, Italy;
gDepartment of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina,
Messina, Italy; hEcole Supérieure des Sciences des Aliments et des Industries Agroalimentaires, Algiers, Algeria
ABSTRACT
The aim was to evaluate the susceptibility of blaESBL producing
Enterobacteriaceae to Slovakian Thymus vulgaris essential oil (TVEO)
alone and in combination with cefotaxime (CTX). TVEO composition
was determined by gas chromatograph-mass spectrometer (GC/MS).
Susceptibility to 21 antibiotics was determined by disc diusion assay.
Genes characterization for resistance to β-lactams was accomplished
by polymerase chain reaction (PCR). The antibacterial activity was
investigated by standard methods. The synergistic interaction was
determined by checkerboard test. Thymol (34.5%), p-cymene (22.27%)
and linalool (5.35%) were the major components present in the TVEO.
The identied strains were multi-drug resistant (MDR). TVEO showed
high activity against all MDR strains, including blaESBL producing
isolates, with inhibition zones and MIC values in the range of 24–
40mm/10μL and 2.87–11.5μg/mL, respectively. TVEO in combination
with CTX showed a synergistic action against blaSHV-12 producing
Escherichia coli (FICI 0.28) and an additive eect vs ESBL producing
Enterobacter cloacae (FICI 0.987).
© 2018 Informa UK Limited, trading as Taylor & Francis Group
KEYWORDS
Thymus vulgaris; essential
oil; antibacterial-resistance;
Enterobacteriaceae; ESBL;
synergism
ARTICLE HISTORY
Received 12 December 2017
Accepted13 April 2018
CONTACT Teresa Gervasi tgervasi@unime.it
Supplemental data for this article can be accessed at https://doi.org/10.1080/14786419.2018.1466124.
2 Q. BENAMEUR ET AL.
1. Introduction
One of the main sources of antibiotic resistant bacteria is represented by food-producing
animals (Gervasi et al. 2014; Lambrecht et al. 2017).
β-lactam antibiotics including cephalosporins are one of the preferred therapeutic options
for treating Enterobacteriaceae infections. The persistent exposure of bacterial strains to a
multitude of β-lactams has induced dynamic and continuous production and mutation of
β-lactamases in these bacteria, expanding their activity even against the newly developed
β-lactam antibiotics. These enzymes are known as extended-spectrum β-lactamases (ESBLs)
(Pitout and Laupland 2008). Production of ESBLs is a signicant resistance-mechanism that
impedes the antimicrobial treatment of infections caused by Enterobacteriaceae and is a
serious threat to the currently available antibiotic armory (Shaikh et al. 2015). Herbal med-
icines have always been a rich source of drug discovery programs, and many plant derived
compounds have shown promising activity against multidrug resistant (MDR) pathogens
(Saeidi et al. 2015). Currently innovative and promising antimicrobial molecules have been
extensively studied (Marino et al. 2016). Potential synergy of some essential oils with anti-
biotics has also been previously postulated, with the aim to alleviate the burden of antimi-
crobial resistance to conventional antimicrobials (Yahiaoui et al. 2017). It has been showed
that Thymus vulgaris essential oil (TVEO) had the best antibacterial activity against some
Enterobacteriaceae species, especially Escherichia coli (Rota et al. 2008; Santurio et al. 2014).
However, little information is available on the antibacterial activity of TVEO against ESBL
producing Enterobacteriaceae strains (Anžlovar et al. 2014), and no study has been conducted
to investigate its synergistic eect with cefotaxime (CTX) against ESBL producing
Enterobacteriaceae strains. The aim of this study was to evaluate the susceptibility of blaESBL
producing Enterobacteriaceae strains to Slovakian origin TVEO and the synergistic interac-
tions between TVEO and CTX.
NATURAL PRODUCT RESEARCH 3
2. Results and discussion
2.1. Chemical composition of TVEO
The GC-MS analysis identied three major components in TVEO (Table 1). It was observed
that thymol (34.50%) was present in the highest concentration in TVEO followed by
p-cymene (22.27%) and linalool (5.35%). Signicant variation is observed in the chemical
composition of the TVEO. Mancini et al. (2015) found that the major component is thymol,
followed by carvacrol and caryophyllene oxide. However, Šegvić Klarić et al. (2007) and El
Hattabi et al. (2016) reported that the major constituent in this essential oil is carvacrol,
followed by p-cymene and E-caryophyllene. As previously reported the variation of the
chemical composition of the EOs may be due to many factors such as the geographical
origin, genetic factors, plant material and harvesting season (Dugo et al. 2014; Tuttolomondo
et al. 2015).
Chemical composition together with the contaminant amount investigation is very impor-
tant for foods characterization (Di Stefano et al. 2014; Mallamace et al. 2014; Naccari et al.
2014; Cicero et al. 2015; Cacciola et al. 2016; Pantano et al. 2016).
2.2. Antimicrobial susceptibility testing
The seven Enterobacteriaceae strains isolated from poultry were identied as E. coli (n = 2),
Klebsiella pneumoniae (n = 2), Enterobacter cloacae (n = 2) and Salmonella sp. (n = 1).
Susceptibility testing results showed that all the isolates were MDR to three or more dierent
antimicrobial agents belonging to dierent classes of antibiotics (Table 2). Among those
strains, four phenotypically conrmed ESBL producing Enterobacteriaceae isolates were
detected. PCR results showed the presence of blaCTX-M gene in E. coli S22/12 and blaSHV gene
in E. coli S77/15 (Table 2). According to the BLAST analysis, the blaCTX-M and blaSHV genes
harbored by E. coli isolates were blaCTX-M-1 (97% query coverage, 98% sequence similarity)
and blaSHV-12 (93% sequence coverage, 97% sequence identity).
Table 1.Thymus vulgaris essential oil composition.
Notes: RT: Retention time, %: percentage of identified compound.
N. Compound name RT RI % N. Compound name RT RI %
1α-pinene 8,45 939 2,8 15 endo-borneol 16.691 1166 1,1
2 camphene 8.943 951 1,2 16 α-terpineol 17.702 1190 1,5
3 β-pinene 9.894 974 0,9 17 γ-terpineol 17.931 1195 0,5
4 β-myrcene 10.387 992 1,2 18 thymol 21.346 1297 34,5
5 p-mentha-1(7).8-diene 10.829 1001 0,1 19 carvacrol 21.507 1307 1,1
6 3-carene 11.058 1007 Tr 20 4-terpinenyl acetate 21.796 1340 0,2
7 o-cymene 11.286 1020 0,1 21 (-)-β-bourbonene 24.217 1412 Tr
8 p-cymene 11.712 1026 22,3 22 caryophyllene 25.339 1417 1,9
9 D-limonene 11.78 1031 1,1 23 γ-muurolene 26.912 1474 0,1
10 1,8 cineole 11.857 1030 0,9 24 δ-cadinene 28.499 1519 0,1
11 γ-terpinene 12.80 1030 0,2 25 δ-cadinene 28.499 1519 0,1
12 Linalool 14.363 1100 5,3 26 caryophylleneoxide 30.309 1578 0,9
13 fenchol 14.813 1121 Tr 27
14 isoborneol 16.359 1146 0,6 28
Total identified 78,7
4 Q. BENAMEUR ET AL.
The occurrence and dissemination of ESBL producing Enterobacteriaceae strains, especially
E. coli, has been increasingly reported over the past few years, both in human (Fernandes et
al. 2014) and veterinary medicine (Belmahdi et al. 2016). β-lactamases are the primary cause
of resistance to β-lactams among members of the family Enterobacteriaceae. Based on pri-
mary structure (Ambler 1980), enzymatic properties and biochemical attributes (Bush et al.
1995), and the increasingly available amino acid sequences (Bush and Jacoby 2010) four
major classes (A, B, C, D) can be acknowledged. Serine β-lactamases belonging to class A
are the most abundant (Philippon et al. 2016), with more than 500 enzymes, including the
most clinically signicant extended spectrum β-lactamases (ESBL) variants, i.e. CTX-M-, TEM-,
and SHV-type enzymes (Bush and Fisher 2011). Among ESBLs, the CTX-M-1 group was dom-
inant in most African surveys on husbandry animals (Alonso et al. 2017). Bacteria that produce
CTX-Ms. are frequently resistant to other classes of antimicrobial agents (Woodford et al.
2004). The MDR bacteria can be transmitted to human through the food chain adding serious
burden to human health (Awad et al. 2016; Benameur et al. 2016).
Surveillance activities in healthy animals worldwide are generating a tremendous amount
of data on ESBL distribution. Majority of SHV variants in this reservoir belong to blaSHV-2,
blaSHV-2a, blaSHV-5, and blaSHV-12 (Liakopoulos et al. 2016). Although, SHV enzymes did not
undergo the explosive dissemination observed for CTX-M-type variants (Cantón et al. 2012),
in recent years they have been found in several Enterobacteriaceae (Liakopoulos et al. 2016).
2.3. Antibacterial activity of TVEO
The initial screening of the antibacterial activity of the TVEO showed its very strong activity
against all the tested strains, with growth inhibition zones ranging from 24 to 40 mm in
diameters (Table 3). The antimicrobial activity of EOs can be classied into three levels: no
Table 2.Characteristic of tested Enterobacteriaceae strains.
Notes: ESBL: extended-spectrum β-lactamase; NA, nalidixicacid; CIP, ciprofloxacin; LVX, levofloxacin; AM, amoxicillin; AMC,
amoxicillin+clavulanicacid; TIC, ticarcillin; PIP, piperacillin; CZ, cefazollin; CF, cephalothin; CTX, cefotaxime; SSS, sulfon-
amides, TMP, trimethoprim; SXT, trimethoprim-sulfamethoxazole, TE, tetracycline; C, chloramphenicol; N, neomycin;
ND: Not determined.
Strain Antimicrobial resistance prole Bla gene
Klebsiella pneumoniae S34/15 (ESBL) NA, CIP, LVX, AM, AMC, TIC, PIP, CZ, CF, CTX, SSS, TMP, SXT, TE, C, N ND
Klebsiella pneumoniae S42/15 AM, SSS, TMP, SXT, TE, C, N /
Escherichia coli S22/12 (ESBL) NA, CIP, LVX,AM, TIC, PIP, CZ, CF, CTX, SSS, TE CTX-M-1
Escherichia coli S77/15 (ESBL) NA, CIP, LVX, AM, TIC, PIP, CZ, CF, CTX, SSS, TMP, SXT, TE SHV-12
Enterobacter cloacae S63/15 (ESBL) NA, CIP, LVX, AM, AMC, TIC, PIP, CZ, CF, CTX, SSS, TMP, SXT, TE, N ND
Enterobacter cloaceae S29/15 AM, AMC, TIC, PIP, CZ, CF, TE, N /
Salmonella sp. S61/15 NA, CIP, LVX, AM, TIC, PIP /
Escherichia coli ATCC 25,922 / /
Table 3.Diameters of inhibition zones and MIC values of TVEO.
Notes: TVEO: Thymus vulgaris essential oil, ESBL: extended spectrum β-lactamase, SD: standard deviation.
Strains Diameter of inhibition zone (mm)±SD (n=3) MIC (μg/mL) of TVEO
Klebsiella pneumoniae S34/15 (ESBL) 39 ± 0.5 2.857
Klebsiella pneumoniae S42/15 35 ± 0.3 11.5
Escherichia coli S22/12 (blaCTX-M-1) 40 ± 0.3 2.857
Escherichia coli S77/15 (blaSHV-12) 30 ± 0.5 11.5
Enterobacter cloacae S63/15 (ESBL) 24 ± 0.7 2.87
Enterobacter cloaceae S29/15 35 ± 0.3 11.5
Salmonella sp. S61/15 35 ± 0.5 11.5
Escherichia coli ATCC 25,922 37 ± 0.6 11.5
NATURAL PRODUCT RESEARCH 5
activity (inhibition zone < 12 mm), moderate activity (<20–12 mm) and strong activity (inhi-
bition zone ≥ 20 mm) (Rota et al. 2008).
The MICs values conrmed the results obtained by the agar disk diusion method (Table 3).
The values ranged from 11.5–2.87 μg/mL against the tested strains. The highest antibacterial
activity of TVEO was observed against blaCTX-M-1 producing E. coli S22/12 and ESBL producing
Klebsiella pneumoniae S34/15 with MIC value of 2.87 μg/mL, with both methods. Moreover,
blaCTX-M-1 producing E. coli was more sensitive to TVEO than blaSHV-12 producing E. coli S77/15.
TVEO also exhibited signicant antibacterial activity against ESBL producing Klebsiella pneu -
moniae than non ESBL producing Klebsiella pneumoniae S42/15.
The FICI of TVEO combined with CTX were calculated to determine their possible inter-
actions against ESBL producing Enterobacteriaceae strains (Table 4). High MIC values for CTX
(32 μg/mL) were obtained against all strains. Checkerboard test results showed a synergistic
eect against blaSHV-12 producing E. coli (FICI 0.28), an additive action against ESBL producing
Enterobacter cloacae (FICI 0.987), and an antagonistic eect against blaCTX-M-1 producing E.
coli and ESBL producing Klebsiella pneumoniae (9.064).
These dose-dependent eects are in agreement with other studies (Rota et al. 2008;
Anžlovar et al. 2014). The antimicrobial properties of essential oils of genus Thymus against
a wide range of resistant microbial strains have been documented extensively (Nabavi et al.
2015). The antimicrobial proprieties of TVEO could be associated with the thymol content,
which has been tested previously and was found to have a signicant antibiotic activity
(Guarda et al. 2011). Also, the synergistic eect between the dierent oil’s compounds, i.e.,
thymol and carvacrol (Guarda et al. 2011) and p-cymene and carvacrol (Ultee et al. 2002)
has also been reported. The mechanism of action of EO and their constituents is not fully
elucidated. This is complicated by the fact that there are many phytochemicals in EO and its
antibacterial activity may not be attributable to one specic mechanism, but probably there
are dierent targets in the bacterial cell (Burt 2004).
There are few published data on combination between CTX and essential oils (Yahiaoui
et al. 2017). This is the rst report concerning the synergistic eects of TVEO in combination
with CTX against ESBL-producing bacteria. This synergistic activity can be attributed to thy-
mol, p-cymene, linalool and other phytochemicals present in minor concentrations in TVEO
and to their dierent targets in the bacterial cell that could potentiate the activity of CTX.
Table 4.Fractional inhibitory concentration index (FICI) of TVEO tested in combination with CTX.
Notes: ESBL: extended spectrum β-lactamase, TVEO: Thymus vulgaris essential oil, CTX: cefotaxime.
Strains
MIC (μg/mL)
cefotaxime
MIC (μg/mL) of
TVEO
MIC of TVEO
combined with
cefotaxime
MIC of cefotaxime
combined with
TVEO FICI
Klebsiella pneumo-
niae S34/15 (ESBL)
32 2.87 23 32 9.064
Escherichia coli
S22/12 (blaCTX-M-1)
32 2.87 23 32 9.064
Escherichia coli
S77/15 (blaSHV-12)
32 11.5 0.36 8 0.28
Enterobacter cloacae
S63/15 (ESBL)
32 2.87 1.38 16 0.987
6 Q. BENAMEUR ET AL.
3. Experimental
See Supplementary materials for source of materials, gas chromatography/mass spectrom-
etry (GC-MS) analysis and evaluation of antimicrobial activity.
4. Conclusion
Extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae has been documented
in humans as well as in food-producing birds, including chickens. In this study, the TVEO
exhibited high activity against all studied MDR Enterobacteriaceae isolates, including ESBL
strains. Moreover, TVEO in combination with CTX showed a synergistic action against blaSHV-12
producing E. coli and an additive eect vs ESBL producing Enterobacter cloacae.
These data suggest essential oil from Slovakian origin Thymus vulgaris, alone or in com-
bination with CTX, has promising antibacterial activity against blaESBL producing MDR
Enterobacteriaceae isolates and it could be used in several elds such as food and pharma-
ceutics. However, further investigations are needed to understand the relation between
TVEO and antibacterial-resistance.
Disclosure statement
No potential conict of interest was reported by the authors.
ORCID
Giacomo Dugo http://orcid.org/0000-0003-0185-6591
References
Alonso CA, Zarazaga M, Ben Sallem R, Jouini A, Ben Slama K, Torres C. 2017. Antibiotic resistance in
Escherichia coli in husbandry animals: the African perspective. Lett Appl Microbiol. 64(5):318–334.
Ambler RP. 1980. The structure of β-lactamases. Philos Trans R Soc Lond B Biol Sci. 289:321–331.
Anžlovar S, Baričevič D, Avguštin JA, Koce JD. 2014. Essential Oil of Common Thyme as a Natural
Antimicrobial Food Additive. Food Technol Biotechnol. 52(2):263–268.
Awad A, Arafat N, Elhadidy M. 2016. Genetic elements associated with antimicrobial resistance
among avian pathogenic Escherichia coli. Ann Clin Microbiol Antimicrob. 15:299. doi:10.1186/
s12941-016-0174-9.
Belmahdi M, Bakour S, Al Bayssari C, Touati A, Rolain JM. 2016. Molecular characterisation of extended-
spectrum β-lactamase- and plasmid AmpC-producing Escherichia coli strains isolated from broilers
in Béjaϊa. Algeria J Glob Antimicrob Resist. 6:108–112.
Benameur Q, Ben-Mahdi MH, Boutaiba Benklaouz M, Tali-Maamar H, Assaous F, Guettou B, Rahal K.
2016. Analysis of high levels of multidrug resistant Escherichia coli from healthy broiler chickens in
Western Algeria. Af J Microbiol Res. 10:1792–1797.
Burt S. 2004. Essential oils: their antibacterial properties and potential applications in foods – a review.
Int J Food Microbiol. 94:223–253.
Bush K, Fisher JF. 2011. Epidemiological expansion, structural studies, and clinical challenges of new
β-Lactamases from gram-negative bacteria. Annu Rev Microbiol. 65:455–478.
Bush K, Jacoby GA. 2010. Updated functional classication of β-lactamases. Antimicrob Agents
Chemother. 54:969–976.
Bush K, Jacoby GA, Medeiros AA. 1995. A functional classication scheme for β-lactamases and its
correlation with molecular structure. Antimicrob Agents Chemother. 39:1211–1233.
NATURAL PRODUCT RESEARCH 7
Cacciola F, Beccaria M, Oteri M, Utczas M, Giurida D, Cicero N, Dugo G, Dugo P, Mondello L. 2016.
Chemical characterisation of old cabbage (Brassica oleracea L. var. acephala) seed oil by liquid
chromatography and dierent spectroscopic detection systems. Nat Prod Res. 30:1646–1654.
Cantón R, González-Alba JM, Galán JC. 2012. CTX-M enzymes: origin and diusion. Front Microbiol.
3:110. doi:10.3389/fmicb.2012.00110.
Cicero N, Corsaro C, Salvo A, Vasi S, Giofré SV, Ferrantelli V, Di Stefano V, Mallamace D, Dugo G. 2015.
The metabolic prole of lemon juice by proton HR-MAS NMR: the case of the PGI interdonato lemon
of Messina. Nat Prod Res. 29:1894–1902.
Di Stefano V, Pitonzo R, Cicero N, D’Oca MC. 2014. Mycotoxin contamination of animal feeding stu:
detoxication by gamma-irradiation and reduction of aatoxins and ochratoxin A concentrations.
Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 31(12):2034–2039.
Dugo G, Franchina FA, Scandinaro MR, Bonaccorsi I, Cicero N, Tranchida PQ, Mondello L. 2014.
Elucidation of the volatile composition of Marsala wines by using comprehensive two-dimensional
gas chromatography. Food Chem. 142:262–268.
El Hattabi L, El Madani N, Charrouf Z, Costa J, Desjobert JM, Tabyaoui M. 2016. Studies on chemical
composition, phenolic contents and antioxidant activities of three Thymus essential oils from
Morocco. Der Pharma Chemica. 8(7):7–15.
Fernandes R, Amador P, Oliveira C, Prudêncio C. 2014. Molecular characterization of ESBL-producing
Enterobacteriaceae in Northern Portugal. Sci World J. 2014:782897.
Gervasi T, Lo Curto R, Minniti E, Narbad A, Mayer MJ. 2014. Application of Lactobacillus johnsonii
expressing phage endolysin for control of Clostridium perfringens. Let Appl Microbiol. 59:355–361.
Guarda A, Rubilar JF, Miltz J, Galotto MJ. 2011. The antimicrobial activity of microencapsulated thymol
and carvacrol. Int J Food Microbiol. 146:144–150.
Lambrecht E, Van Meervenne E, Boon N, Van de Wiele T, Wattiau P, Herman L, Heyndrickx M, Van Coillie
E. 2017. Characterization of cefotaxime- and ciprooxacin-resistant commensal Escherichia coli
originating from Belgian farm animals indicates high antibiotic resistance transfer rates. Microb
Drug Resist. doi:10.1089/mdr.2017.0226.
Liakopoulos A, Mevius D, Ceccarelli D. 2016. A review of SHV extended-spectrum β-Lactamases:
neglected yet ubiquitous. Front Microbiol. 7:1374. doi:10.3389/fmicb.2016.01374.
Mallamace D, Corsaro C, Salvo A, Cicero N, Macaluso Giangrosso G, Ferrantelli V, Dugo G. 2014.
A multivariate statistical analysis coming from the NMR metabolic prole of cherry tomatoes (The
Sicilian Pachino case). Physica A. 401:112–117.
Mancini E, Senatore F, Del Monte D, De Martino L, Grulova D, Scognamiglio M, Snoussi M, De Feo V.
2015. Studies on chemical composition, antimicrobial and antioxidant activities of Five Thymus
vulgaris L. Essent Oils Mol. 20:12016–12028.
Marino A, Zengin G, Nostro A, Ginestra G, Dugo P, Cacciola F, Miceli N, Taviano MF, Filocamo A, Bisignano G,
et al. 2016. X-rayAntimicrobial activities, toxicity and phenolic composition of Asphodeline anatolica
E. Tuzlaci leaf extracts from Turkey. Nat Prod Res. 2:1–9.
Nabavi SM, Marchese A, Izadi M, Curti V, Daglia M, Nabavi SF. 2015. Plants belonging to the genus
Thymus as antibacterial agents: from farm to pharmacy. Food Chem. 173:339–347.
Naccari C, Macaluso A, Giangrosso G, Naccari F, Ferrantelli V. 2014. Risk assessment of heavy metals
and pesticides in honey From Sicily (Italy). J Food Res. doi:10.5539/jfr.v3n2p107.
Pantano L, Lo Cascio G, Alongi A, Cammilleri G, Vella A, Macaluso A, Cicero N, Migliazzo A, Ferrantelli
V. 2016. Fatty acids determination in Bronte pistachios by gas chromatographic method. Nat Prod
Res. doi:10.1080/14786419.2016.1180599.
Philippon A, Slama P, Dény P, Labia R. 2016. A structure-based classication of class A β-Lactamases, a
broadly diverse family of enzymes. Clin Microbiol Rev. 29:29–57.
Pitout JD, Laupland KB. 2008. Extended-spectrum β-lactamase-producing Enterobacteriaceae: an
emerging public health concern. The Lan Infect Dis. 8(3):159–166.
Rota MC, Herrera A, Martínez RM, Sotomayor JA, Jordán MJ. 2008. Antimicrobial activity and chemical
composition of Thymus vulgaris, Thymus zygis and Thymus hyemalis essential oils. Food Control.
19:681–687.
8 Q. BENAMEUR ET AL.
Saeidi S, Boroujeni NA, Ahmadi H, Hassanshahian M. 2015. Antibacterial activity of some plant extracts
against extended–Spectrum Beta-lactamase producing Escherichia coli Isolates. Jundishapur J
Microbiol. 8(2):e15434.
Santurio DF, Jesus FPK, Zanette RA, Schlemmer KB, Fraton A, Martins Fries LL. 2014. Antimicrobial
Activity of the Essential Oil of Thyme and of Thymol against Escherichia coli Strains. Acta Sci Vet.
42:1234.
Šegvić Klarić M, Kosalec I, Mastelić J, Piecková E, Pepeljnak S. 2007. Antifungal activity of thyme (Thymus
vulgaris L.) essential oil and thymol against moulds from damp dwellings. Letters appl Microbial.
44(1):36–42.
Shaikh S, Fatima J, Shakil S, Rizvi SM, Kamal MA. 2015. Antibiotic resistance and extended spectrum
beta-lactamases: Types, epidemiology and treatment. Saudi J Biol Sci. 22:90–101.
Tuttolomondo T, Giacomo D, Giuseppe R, Leto C, Napoli EM, Cicero N, Gervasi T, Giuseppe V, Leone R,
Licata M, La Bella S. 2015. Study of quantitative and qualitative variations in essential oils of Sicilian
Rosmarinus ocinalis L. Nat Prod Res. 29, 20:1928–1934.
Ultee A, Bennik MH, Moezelaar R. 2002. The phenolic hydroxyl group of carvacrol is essential for action
against the foodborne pathogens Bacillus cereus. Appl Environ Microbiol. 68:1561–1568.
Woodford N, Ward ME, Kaufmann ME, Turton J, Fagan EJ, James D, Johnson AP, Pike R, Warner M,
Cheasty T, et al. 2004. Community and hospital spread of Escherichia coli producing CTX-M extended-
spectrum β-lactamases in the UK. J Antimicrob Chemother. 54(4):735–743.
Yahiaoui F, Benameur Q, Ben-mahdi MH. 2017. antibacterial activity of Mentha pulegium essential oil
against avian isolated ESBL producing bacteria and its synergistic potential with antibiotics. Int J
Pharm Pharm Sci. 9(6):35–41.
... The antibacterial properties of T. vulgaris EO have been extensively studied, revealing its potency against a wide range of bacterial strains, including S. aureus, E. coli, and P. aeruginosa, and these investigations have confirmed the antibacterial activity of this EO. [40,41] Furthermore, in the present study, the main volatile component of T. vulgaris EO was thymol (55.82%). Several studies have reported that thymol plays an important role in the antibacterial activity. ...
Article
Biofilm formation and virulence factor production by Pseudomonas aeruginosa are identified as the main mechanisms of its antibiotic resistance and pathogenicity. In this context, the study of the chemical composition of three Algerian essential oils (EOs) and the screening of their antibacterial, anti‐biofilm and virulence factor inhibitory activities enabled us to select the Thyme EO as the best oil to control the P. aeruginosa strain isolated from hospital environments. This EO composed essentially of thymol (55.82%) associated with carvacrol, had an anti‐adhesive activity of 69.8% at a concentration of 5µL/mL, and a biofilm eradication activity of 74.86% at a concentration of 2.5µL/mL. This EO was able to inhibit P. aeruginosa twitching motility by 100% at a concentration of 2.5µL/mL. Pyocyanin was inhibited by 99.33%, at a concentration of 1.25µL/mL. Rhamnolipids were significantly inhibited by 63.33% in the presence of Thyme EO at a concentration of 1.25µL/mL after 24h of incubation. Molecular docking showed that carvacrol and thymol can bind to the three QS receptors in P. aeruginosa, RhlR, LasR, and PqsR, with good affinities, which can inhibit or modulate biofilm formation and the production of certain virulence factors. Keywords antibiofilm, thymol, essential oil, Pseudomonas aeruginosa, pyocyanin, rhamnolipids, in silico study.
... Clove (Syzygium aromaticum L.) and thyme (Thymus vulgaris L.) essential oils are two of the most valued essential oils that are among the most appreciated essential oils, especially due to their significant antimicrobial properties. A blooming plant native to Southern Europe and found all over the world, Thymus vulgaris, also referred to as thyme, is a member of the Lamiaceae family and has significant pharmacological qualities [20]. According to Mohammed et al. [21], thyme extracts, including essential oil extracted from plant aerial parts (flowers and leaves), has shown antibacterial properties against both Gram-positive and Gram-negative bacteria. ...
Article
Full-text available
This study investigated the antimicrobial and antioxidant activity of clove (Syzygium aromaticum) and thyme (Thymus vulgaris) essential oils, which are traditionally used as food packaging materials. The essential oils were extracted using hydro distillation and their antimicrobial activity was evaluated against common foodborne pathogens, including Escherichia coli, Staphylococcus aureus, Salmonella enterica, and Listeria monocytogenes. The antioxidant activity was determined using the DPPH (2,2-dip). The study found that both clove and thyme essential oils exhibited antimicrobial activity against all four foodborne pathogens tested, with clove oil having the strongest activity. In addition, both essential oils showed antioxidant activity, with clove oil having the highest antioxidant capacity. Based on these results, clove and thyme essential oils have potential as natural food preservatives. This study provides further evidence of the beneficial properties of these two herbs and their potential use in food packaging. However, more research is needed to optimize the use of these essential oils and to ensure their safety and efficacy.
... We also found the existence of other active substances, noting that they were the same active substances found in T.vulgaris in the previous analysis (15) . Linalool were key constituents contained in GC-MC of Thymus volatile oil, which is already known to have antibacterial activity (16) . ...
Article
This study was carried out to evaluate the antibacterial activity of aqueous and organic extracts of Thymus vulgaris L. (Lamiaceae). The hexan (HEX), ethanol (ETH) and water (WAT) extracts from aerial parts of T. vulgaris exhibited antimicrobial activity against slow growth mycobacteria – SGM (n = 49) and rapid growth mycobacteria – RGM (n = 50) strains isolated from diseased ornamental fish. The MICAV values of HEX, ETH, and WAT extracts against RGM strains were found to be at 146.50 μg/mL, 728.00 μg/mL, and > 800 μg/mL, respectively. The MICAV values of HEX, ETH, and WAT extracts against SGM strains were found to be at 50.77 μg/mL, 253.06 μg/mL, and > 800 μg/mL, respectively. The most active extract against RGM and SGM strains was the hexane extract. Its chemical composition was determined using GC-MS, which allowed the identification of 53 compounds. The major chemical compounds in HEX extracts were found to be thymol (27.35%), tetratetracontane (19.68%), dotriacontane (10.34%), p-cymene (5.92%), stigmast-5-en-3-ol (4.89%), carvacrol (2.64%), thymoquinone (2.00%), (1r)-1,6,6-trimethylcis- bicyclo[3.3.0]octan-3-one (2.52%), 5,10-dihexyl-5,10-dihydro indole[3,2b]indole-2,7-dicarbaldehyde (2.15%), and linalyl anthranilate (1.06%), the proportion of other components being below 1%. In conclusion, among the tested extracts, the HEX extract exhibits the strongest properties against nontuberculosis mycobacteria isolated from diseased ornamental fish.
Article
Full-text available
The increasing resistance of microbes to standard antibiotics is a major concern in the management of contagious infections and has led to an unprecedented increase in mortality rates. The identification of the microbial "superbugs" responsible for hospital-acquired pathogenic maladies has prompted a significant amount of research in recent years, with the hope of revealing potentially beneficial answers to the ensuing health challenges by leveraging on ethnomedicinal remedies. The antibacterial activity of phytophenols was demonstrated against a wide range of pathogens, including those that have developed resistance to conventional antibiotics via their aligning resistance mechanisms. Here, we have recapitulated the most important bacterial drug resistance pathways and elucidated the dynamics of the phytophenols in Thymus vulgaris, Piper nigrum, Nigella sativa, and Annona muricata in potentially hindering and disrupting the antibiotic resistance dynamics of microbial superbugs implicated in nosocomial infections. The in-vitro antibacterial activity of phytophenolic substances and their synergistic selectivity with chemotherapeutics validated an efficacy in combating antibiotic resistance mechanisms in microbial superbugs in-vitro. The mechanisms of antibiotic resistance synthesis and polyphenolic interactions with microbial cellular pathways via antioxidant properties showed promising prospects in ameliorating the public health threat posed antibiotic-resistant superbugs. The major challenge in developing new phytochemicals with public health importance for microbial "superbugs" is the replication of in-vitro explorations via in-vivo experimentation and, ultimately, human medical testing for clinical trial. However, additional research is needed to confirm the activity pathways and stability of these phytoactive compounds, as a number of these phytoactives exhibit synergistic antimicrobial effects with chemotherapeutics.
Article
Owing to their beneficial functional capabilities, essential oils were largely used. However, their low aqueous solubility, instability, and high volatility urged scientists to their encapsulation with cyclodextrins (CDs) to tackle their shortcomings. In this study, the co-precipitation method was used to prepare β-CD/Eucalyptus globulus essential oil (EGEO) inclusion complexes (ICs). β-CD/EGEO ICs were prepared at ratios (w:w) 1:2 and 1:4 with an encapsulation efficiency of 93 and 96%, respectively. The ICs characterization using the Fourier transform Infrared spectroscopy, differential scanning calorimetry, X-ray powder diffraction, Dynamic Light Scattering, and Laser Doppler Velocimetry confirmed the formation of β-CD/EGEO ICs. The insecticidal activity of the free EGEO and ICs was explored and displayed that the complex β-CD/EGEO 1:4 had the highest activity with the lowest LC50 against Ephestia kuehniella larvae (5.03 ± 1.16 mg/g) when compared to the free oil (8.38 ± 1.95 mg/g). Molecular docking simulations stipulated that the compound α-Bisabolene epoxide had the best docking score (ΔG = 􀀀 7.4 Kcal/mol) against the selected insecticidal target α-amylase. Additionally, toxicity evaluation of the studied essential oil suggested that it could be safely used as a potent bioinsecticide as compared to chemical insecticides. This study reveals that the formation of β-CD/EGEO ICs enhanced the oil activity and stability and could be a promising and safe tool to boost its application in food or pharmaceutical fields.
Article
The essential oil of Thymus vulgaris (TVEO) has been used in traditional medicine for centuries. However, its low solubility and high volatility have limited its usage. In this study, TVEO was extracted, and its chemical composition was identifed. The TVEO was extracted using a Clevenger-type apparatus and identifed using Gas Chromatography/Mass Spectrometry (GC/MS). An inclusion complex was then formulated with β-cyclodextrin (βCD) to enhance its solubility, and the antibacterial activity was tested against 14 multidrug-resistant bacteria. When treated with the complex, the inactivation kinetics of Salmonella typhimurium were evaluated under simulated intestinal conditions. Thymol and carvacrol were identifed as the signifcant components of TVEO, comprising 47.53% and 19.27% of the oil, respectively. The solubility diagram of enclosed Thymol exhibited a Bs-type profle, with an association constant (Ks) of 202.35 M−1 and a complexation efficiency of 55.07% for the formulated complex TVEO-βCD. The antibacterial activity demonstrated signifcant inhibition against all tested strains except for three. The study demonstrates the effectiveness of the TVEO-β-CD complex against S. typhimurium in intestinal conditions, a novel application. Unlike prior research, our work focuses on this complex's efficacy, specifcally against Salmonella, showing prolonged inhibitory effects. This reveals the enhanced antibacterial activity of β-CD in solubilising TVEO, ofering potential as an antimicrobial agent. Keywords: Thymus vulgaris essential oil · β-cyclodextrin · Inclusion complex · Antibacterial efect · Simulated intestinal conditions
Chapter
Consumption of contaminated food affects millions and may even lead to death. For this reason, foodborne outbreaks are considered a public health problem. Commonly, eating food contaminated with pathogenic bacteria involves treatment with antimicrobials, like antibiotics. However, there is the aggravating circumstance of food contamination by resistant bacteria species (RBS). Microbial resistance to antimicrobials is an ecological problem and appears when microorganisms adapt to continuous exposure to an antimicrobial agent. Thus, there is an interest in studying potential safe alternatives to conventional antimicrobials. Natural antimicrobials have been increasingly studied because they are compounds naturally present in plants. Essential oils (EOs) are considered a complex mixture of aromatic and volatile compounds and have the potential to be applied as natural additives due to their natural biological activities, such as antibacterial, antifungal, and antiparasitic. Different EOs have exhibited antimicrobial properties against Gram-positive and Gram-negative bacteria species. This chapter describes some investigations about the antimicrobial effect of different EOs against RBS.
Article
This study aimed to determine the chemical composition of essential oils from A. gratíssima, O. basilicum, S. microphylla, T. riparia, and T. vulgaris and their antioxidant and antifungal activities against Alternaria alternata strains. Gas chromatography-mass spectrometry revealed that the major components of the essential oils were terpenes. The essential oils of S. microphylla and T. riparia showed higher antioxidant activities than the others. The essential oils of S. microphylla and T. riparia inhibited the growth of the fungus at 3.10 and 6.05 µL/mL, respectively. The essential oil of T. riparia inhibited 93.9% of the growth of the fungus and showed the highest in vivo efficiency in severity reduction (76.2%). We conclude that the essential oil of T. riparia shows promising antifungal activity and is an environmentally safe alternative for controlling fungal diseases in vegetables.
Article
Full-text available
β-lactamases are the primary cause of resistance to β-lactams among members of the family Enterobacteriaceae. SHV enzymes have emerged in Enterobacteriaceae causing infections in health care in the last decades of the Twentieth century, and they are now observed in isolates in different epidemiological settings both in human, animal and the environment. Likely originated from a chromosomal penicillinase of Klebsiella pneumoniae, SHV β-lactamases currently encompass a large number of allelic variants including extended-spectrum β-lactamases (ESBL), non-ESBL and several not classified variants. SHV enzymes have evolved from a narrow- to an extended-spectrum of hydrolyzing activity, including monobactams and carbapenems, as a result of amino acid changes that altered the configuration around the active site of the β -lactamases. SHV-ESBLs are usually encoded by self-transmissible plasmids that frequently carry resistance genes to other drug classes and have become widespread throughout the world in several Enterobacteriaceae, emphasizing their clinical significance.
Article
Full-text available
Objective: The aim of this study was to evaluate the antibacterial effect of Algerian Mentha pulegium essential oil against extended-spectrum β-lactamases (ESBL) producing bacteria isolated from avian livestock. The synergistic interactions between conventional antibiotics and Mentha pulegium essential oil were assessed.Methods: Essential oil composition was determined by gas chromatograph-flame ionization detector (GC/FID), gas chromatograph-mass spectrometer (GC/MS) analysis.Antibacterial activity of Mentha pulegium essential oil against ESBL producing bacteria was investigated by disc diffusion assay. Minimum inhibitory concentration (MIC) of essential oil and it synergistic interaction with conventional antibiotics were determined by micro-broth dilution method and checkerboard test, respectively.Results: The results indicate that Mentha pulegium essential oil with a high amount of pulegone (88.78%) had high inhibitory activity against the tested strains and particularly displays a satisfactory action against the studied ESBL producing bacteria from animal origin, with a diameter ranging from 13 to 26 mm. Out of 51 combinations tested between essential oil and antibiotics 60.78 % showed total synergy, 13.72 % had presented a partial synergy. The best antibacterial activities were obtained with the combination of Mentha pulegium essential oil and cefazolin, cefotaxime and gentamycin.Conclusion: This study allowed concluding that Mentha pulegium essential oil showed not only satisfactory antibacterial properties, but also acts synergistically combined with conventional antibiotics, which make it a promising alternative to antimicrobial drugs; beside that, it might reduce the minimum effective dose of the drugs which minimizes their possible side effects.
Article
Full-text available
In the last years different surveillances have been published in Africa, especially in Northern countries, regarding antimicrobial resistance among husbandry animals. Information is still scarce, but the available data shows a worrying picture. Although the highest resistance rates have been described against tetracycline, penicillins and sulphonamides, prevalence of plasmid mediated quinolone resistance genes and extended-spectrum β-lactamase (ESBL) are being increasingly reported. Among ESBLs, the CTX-M-1 group was dominant in most African surveys, being CTX-M-15 the main variant both in animals and humans, except in Tunisia where CTX-M-1 was more frequently detected among E. coli from poultry. Certain blaCTX-M-15-harboring clones (ST131/B2 or ST405/D) are mainly identified in humans but they have also been reported in livestock species from Tanzania, Nigeria or Tunisia. Moreover, several reports suggest an inter-host circulation of specific plasmids (e.g. blaCTX-M-1-carrying IncI1/ST3 in Tunisia, IncY and Inc-untypeable replicons co-harboring qnrS1 and blaCTX-M-15 in Tanzania and the worldwide distributed blaCTX-M-15-carrying IncF-type plasmids). International trade of poultry meat seems to have contributed to the spread of other ESBL variants, such as CTX-M-14, and clones. Worryingly, first descriptions of OXA-48 and OXA-181-producing E. coli have been recently documented in cattle from Egypt, and the emergent plasmid-mediated colistin resistance mcr-1 gene has been also identified in chickens from Algeria, Tunisia and South Africa. These data reflect the urgent need of a larger regulation in the use of veterinary drugs and the implementation of surveillance programmes in order to decelerate the advance of antimicrobial resistance in this continent. This article is protected by copyright. All rights reserved.
Article
Full-text available
One hundred and two Escherichia coli strains isolated from healthy broiler chickens collected from April 2012 to November 2014 in seven geographic areas of western Algeria were studied. Susceptibility pattern to 11 antimicrobial agents was determined by disk diffusion method as recommended by the Clinical Laboratory Standard Institute (CLSI). Antibiograms revealed high levels of resistance to quinolones and fluoroquinolones including nalidixic acid (100%), flumequin (86, 27%) and enrofloxacin (84, 31%), and to other antibiotics, notably: tetracycline (92, 15%), trimethoprim-sulfamethoxazol (80, 39%) and amoxicillin (68, 62%). However, a moderate percentage of strains were resistant to neomycin (31, 37%), chloramphenicol (27, 45%) and nitrofurantoin (21, 56%). Only 7, 84% of the isolates were resistant to gentamicin and all the isolates were susceptible to colistin. All isolated E. coli were resistant to at least three antibiotics. 96, 08% and 91, 12% of the isolates were resistant to at least four and five antimicrobials, respectively. Twenty eight antibiotic resistance patterns of E. coli strains were detected, of which 11 were present significantly. The results of this survey indicate very high levels of resistance to quinolones and to other antibiotics in E. coli from healthy broiler chickens in Algeria, and suggested that this reservoir of resistance may affect the therapeutic potential of fluoroquinolones in human and veterinary medicine.
Article
Full-text available
Background Avian-pathogenic Escherichia coli (APEC) are pathogenic strains of E. coli that are responsible for one of the most predominant bacterial disease affecting poultry worldwide called avian colibacillosis. This study describes the genetic determinants implicated in antimicrobial resistance among APEC isolated from different broiler farms in Egypt. Methods A total of 116 APEC were investigated by serotyping, antimicrobial resistance patterns to 10 antimicrobials, and the genetic mechanisms underlying the antimicrobial-resistant phenotypes. ResultsAntibiogram results showed that the highest resistance was observed for ampicillin, tetracycline, nalidixic acid, and chloramphenicol. The detected carriage rate of integron was 29.3% (34/116). Further characterization of gene cassettes revealed the presence gene cassettes encoding resistance to trimethoprim (dfrA1, dfrA5, dfrA7, dfrA12), streptomycin/spectinomycin (aadA1, aadA2, aadA5, aadA23), and streptothricin (sat2). To our knowledge, this the first description of the presence of aadA23 in APEC isolates. Analysis of other antimicrobial resistance types not associated with integrons revealed the predominance of resistance genes encoding resistance to tetracycline (tetA and tetB), ampicillin (blaTEM), chloramphenicol (cat1), kanamycin (aphA1), and sulphonamide (sul1 and sul2). Among ciprofloxacin-resistant isolates, the S83L mutation was the most frequently substitution observed in the quinolone resistance-determining region of gyrA (56.3%). The blaTEM and blaCTX−M−1 genes were the most prevalent among APEC isolates producing extended-spectrum beta-lactamase (ESβL). Conclusions These findings provided important clues about the role of integron-mediated resistance genes together with other independent resistance genes and chromosomal mutations in shaping the epidemiology of antimicrobial resistance in E. coli isolates from poultry farms in Egypt.
Article
Full-text available
A gas chromatographic with flame ionization detector (GC-MS FID) method for the identification and quantification of fatty acids based on the extraction of lipids and derivatisation of free acids to form methyl esters was developed and validated. The proposed method was evaluated to a number of standard FAs, and Bronte pistachios samples were used for that purpose and to demonstrate the applicability of the proposed method. In this regard, repeatability, mean and standard deviation of the analytical procedure were calculated. The results obtained have demonstrated oleic acid as the main component of Bronte pistachios (72.2%) followed by linoleic acid (13.4%) and showed some differences in composition with respect to Tunisian, Turkish and Iranian pistachios.
Article
Full-text available
This study aimed to characterise the molecular support of antibiotic resistance in expanded-spectrum cephalosporin (ESC)-resistant Escherichia coli isolates recovered from healthy broilers in Béjaïa, northeast Algeria. A total of 61 intestinal swabs from slaughtered broilers from four regions in Béjaïa locality, Algeria, were collected between February–April 2014, from which 20 ESC-resistant E. coli strains were isolated. Escherichia coli isolates were identified by classical biochemical and MALDI-TOF methods. Antibiotic susceptibility testing was performed using disk diffusion and Etest methods. Screening for β-lactamases, aminoglycoside-modifying enzyme (AME)-encoding genes and qnr determinants was performed by PCR and sequencing. Clonal relatedness was determined using molecular typing by multilocus sequence typing (MLST). Antibiotic susceptibility testing revealed that the isolates showed high rates of resistance (>90%) to amoxicillin, amoxicillin/clavulanic acid, piperacillin/tazobactam, aztreonam, ceftazidime, streptomycin, tobramycin, nalidixic acid and ciprofloxacin. Low rates of resistance were observed for kanamycin (35%), amikacin (30%), cefoxitin (20%) and cefotaxime (15%). Molecular characterisation revealed that all of the isolates expressed the blaTEM-1 gene. Fourteen of them harboured the blaSHV-12 gene, two harboured the blaCTX-M-1 gene and four isolates harboured blaCMY-2. Screening for AME-encoding genes demonstrated that all isolates contained the aadA gene. In addition, qnrA was detected as the quinolone resistance determinant in 13 isolates. MLST revealed four known sequence types (STs), including ST744, ST38, ST1011 and ST2179, as well as one new sequence type (ST5086). Here we report the first study describing the clonal diversity of extended-spectrum β-lactamase (ESBL)- and plasmid AmpC-producing E. coli isolated from healthy broilers in Algeria.
Article
Food-producing animals represent one of the sources of antibiotic resistant commensal bacteria. There is an increasing awareness that these bacteria might have the potential to transfer their resistance genes to other (pathogenic) bacteria. In this study, 50 commensal Escherichia coli strains originating from food-producing animals and resistant to the "highest priority, critically important antibiotics" cefotaxime and/or ciprofloxacin, were selected for further characterization. For each strain (i) an antibiogram, (ii) the phylogenetic group, (iii) plasmid replicon type, (iv) presence and identification of integrons, and (v) antibiotic resistance transfer ratios were determined. Forty-five of these strains were resistant to 5 or more antibiotics, and 6 strains were resistant to 10 or more antibiotics. Resistance was most common to ampicillin (100%), sulfamethoxazole, ciprofloxacin (82%), trimethoprim, tetracycline (74%), cefotaxime, (70%) and ceftazidime (62%). Phylogenetic groups A (62%) and B1 (26%) were most common, followed by C (8%) and E (4%). In 43 strains, more than 1 replicon type was detected, with FII (88%), FIB (70%), and I1 (48%) being the most encountered types. Forty strains, positive for integrons, all harbored a class I integron and seven of them contained an additional class II integron. No class III integrons were detected. The antibiotic resistance transfer was assessed by liquid mating experiments. The transfer ratio, expressed as the number of transconjugants per recipient, was between 10(-5) and 10(0) for cefotaxime resistance and between 10(-7) and 10(-1) for ciprofloxacin resistance. The results of the current study prove that commensal E. coli in food-production animals can be a source of multiple resistance genes and that these bacteria can easily spread their ciprofloxacin and cefotaxime resistance.
Article
The thymus belongs to the family Lamiaceae, commonly used as spice and medicinal herb, recognized by several pharmacological properties, such as antispasmodic, antiseptic, antibacterial and many other bioactivities. The chemical composition and the antioxidant activity of thymus's essential oils of three different Moroccan regions were studied. The essential oils were identified by chromatographic analysis (GC and GC/MS). Indeed, in essential oils of Thymus vulgaris and Thymus satureoides the main compound determined was the Carvacrol he represents 78.4% and 49.3% respectively. The quantitative determinations of total phenolics, total flavonoids, and various antioxidant activities (1,1-Diphenyl-l-2-picryl-hydrazyl radical and 2,2-azinobis 3 ethylbenz-thiazoline sulfonate) of plants extracts have carried out using colorimetric methods. The total phenolic content, expressed as μg of gallic acid equivalent (GAE) per mg of extract, was found varied between 121,44 and 143,17 μg GAE/mg and the IC50 values of 1,1-Dipheny l-2-picryl-hydrazyl radical (DPPH) free radical scavenging activity between 5,141 and 5,749 μg/mL. This study indicated the three oils of thymus possessed high antioxidant properties, therefore it can be considered as a bioresource of phenolic and source of natural antioxidant.
Article
Near-infrared (NIR) and X-ray fluorescence spectra were recorded for 15 different samples of marmora, from the Mediterranean Basin and of different colours. After appropriate pretreatment (SNV transform + second derivative), the results were subjected to principal component analysis (PCA) treatment with a view to differentiating them. The observed differences among the samples were chemically interpreted by highlighting the NIR wavelengths and minerals, respectively, contributing the most to the PCA models. Moreover, a mid-level data fusion protocol allowed integrating the information from the different techniques and, in particular, to correctly identify (based on the distance in the score space) three test samples of known type. Moreover, it should be stressed that positive results on the differentiation and identification of marmora were obtained using two completely non-invasive, non-destructive and relatively inexpensive techniques, which can also be used in situ.