[Show abstract][Hide abstract] ABSTRACT: Endophytic microbes have attracted considerable attention as a completely new source of pharmaceuticals in recent years. An endophytic Fusarium tricinctum was isolated from Rhododendron tomentosum, a shrub that is found widely across the northern hemisphere. The endophytic F. tricinctum produced antimicrobial compounds that were active against Staphylococcus carnosus, Candida albicans and C. utilis. The transcriptome of the F. tricinctum was sequenced, and a total of 12,006 contigs were assembled, having an N50 value of 1390 bp. Analysis of the transcriptomic PD library of F. tricinctum yielded an antimicrobial peptide named Trtesin. The expression of Trtesin transcripts was >1000 fold in the mRNA library originating from PDB-grown fungi exhibiting high antimicrobial activity compared to FG4-grown fungi with no antimicrobial activity. Trtesin was cloned, expressed, and purified in pET32(a), and it consisted of 52 amino acids with 6 cysteine molecules. The molecular weight of Trtesin is 6138.92 Da. An additional N-terminal sequencing was done to confirm the intact peptide, as well as to check the correct amino acid sequence. The MIC of Trtesin was determined against several bacteria as 64 μg/mL, and peptide showed a mild activity against F. oxysporum in agar diffusion assay, as a zone of inhibition of 10 mm was formed at 100 μg of peptide.
[Show abstract][Hide abstract] ABSTRACT: Antimicrobial peptides are a new class of antibiotics that are promising for pharmaceutical applications, since they have retained efficacy throughout evolution. One class of antimicrobial peptides are the defensins, that have been found in different species. Here we describe a new fungal defensin, eurocin. Eurocin acts against a range of gram-positive human pathogens, but not against gram-negative bacteria. Eurocin consists of 42 amino acids, forming a cysteine-stabilized α/β fold. Thermal denaturation data point shows the disulphide bridges being responsible for the stability of the fold. Eurocin does not form pores in cell membranes at physiologically relevant concentrations, it does, however, lead to limited leakage of a fluorophore from small unilamellar vesicles. Eurocin interacts with detergent micelles, and it inhibits the synthesis of cell walls by binding equimolarly to the cell wall precursor lipid II.
No preview · Article · Oct 2012 · Journal of Biological Chemistry
[Show abstract][Hide abstract] ABSTRACT: Commercially produced sterile green bottle fly Lucilia sericata maggots are successfully employed by practitioners worldwide to clean a multitude of chronic necrotic wounds and reduce wound bacterial burdens during maggot debridement therapy (MDT). Secretions from the maggots exhibit antimicrobial activity along with other activities beneficial for wound healing. With the rise of multidrug-resistant bacteria, new approaches to identifying the active compounds responsible for the antimicrobial activity within this treatment are imperative. Therefore, the aim of this study was to use a novel approach to investigate the output of secreted proteins from the maggots under conditions mimicking clinical treatments.
cDNA libraries constructed from microdissected salivary glands and whole maggots, respectively, were treated with transposon-assisted signal trapping (TAST), a technique selecting for the identification of secreted proteins. Several putative secreted components of insect immunity were identified, including a defensin named lucifensin, which was produced recombinantly as a Trx-fusion protein in Escherichia coli, purified using immobilized metal affinity chromatography and reverse-phase HPLC, and tested in vitro against Gram-positive and Gram-negative bacterial strains.
Lucifensin was active against Staphylococcus carnosus, Streptococcus pyogenes and Streptococcus pneumoniae (MIC 2 mg/L), as well as Staphylococcus aureus (MIC 16 mg/L). The peptide did not show antimicrobial activity towards Gram-negative bacteria. The MIC of lucifensin for the methicillin-resistant S. aureus and glycopeptide-intermediate S. aureus isolates tested ranged from 8 to >128 mg/L.
The TAST results did not reveal any highly secreted compounds with putative antimicrobial activity, implying an alternative antimicrobial activity of MDT. Lucifensin showed antimicrobial activities comparable to other defensins and could have potential as a future drug candidate scaffold, for redesign for other applications besides the topical treatment of infected wounds.
Full-text · Article · Aug 2010 · Journal of Antimicrobial Chemotherapy
[Show abstract][Hide abstract] ABSTRACT: Plectasin is the first defensin-type antimicrobial peptide isolated from a fungus and has potent activity against gram-positive bacteria. By using an experimental meningitis model, the penetration of plectasin into the cerebrospinal fluid (CSF) of infected and uninfected rabbits and the bactericidal activities in CSF of the plectasin variant NZ2114 and ceftriaxone against a penicillin-resistant Streptococcus pneumoniae strain (NZ2114 and ceftriaxone MICs, 0.25 and 0.5 microg/ml, respectively) were studied. Pharmacokinetic analysis showed that there was a significantly higher level of CSF penetration of NZ2114 through inflamed than through noninflamed meninges (area under the concentration-time curve for CSF/area under the concentration-time curve for serum, 33% and 1.1%, respectively; P = 0.03). The peak concentrations of NZ2114 in purulent CSF were observed approximately 3 h after the infusion of an intravenous bolus of either 20 or 40 mg/kg of body weight and exceeded the MIC >10-fold for a 6-h study period. Treatment with NZ2114 (40 and 20 mg/kg at 0 and 5 h, respectively; n = 11) caused a significantly higher reduction in CSF bacterial concentrations than therapy with ceftriaxone (125 mg/kg at 0 h; n = 7) at 3 h (median changes, 3.7 log(10) CFU/ml [interquartile range, 2.5 to 4.6 log(10) CFU/ml] and 2.1 log(10) CFU/ml [interquartile range, 1.7 to 2.6 log(10) CFU/ml], respectively; P = 0.001), 5 h (median changes, 5.2 log(10) CFU/ml [interquartile range, 3.6 to 6.1 log(10) CFU/ml] and 3.1 log(10) CFU/ml [interquartile range, 2.6 to 3.7 log(10) CFU/ml], respectively; P = 0.01), and 10 h (median changes, 5.6 log(10) CFU/ml [interquartile range, 5.2 to 5.9 log(10) CFU/ml] and 4.2 log(10) CFU/ml [interquartile range, 3.6 to 5.0 log(10) CFU/ml], respectively; P = 0.03) after the start of therapy as well compared to the CSF bacterial concentrations in untreated rabbits with meningitis (n = 7, P < 0.05). Also, significantly more rabbits had sterile CSF at 5 and 10 h when they were treated with NZ2114 than when they were treated with ceftriaxone (67% [six of nine rabbits] and 0% [zero of seven rabbits], respectively, at 5 h and 75% [six of eight rabbits] and 14% [one of seven rabbits], respectively, at 10 h; P < 0.05). Due to its excellent CSF penetration and potent bactericidal activity in CSF, the plectasin variant NZ2114 could be a promising new option for the treatment of CNS infections caused by gram-positive bacteria, including penicillin-resistant pneumococcal meningitis.
Full-text · Article · Feb 2009 · Antimicrobial Agents and Chemotherapy
[Show abstract][Hide abstract] ABSTRACT: Background: NZ2114, a plectasin derivative, is a novel antibiotic with activity against Gram-positive (GP) pathogens. To understand the mode of action of NZ2114, MBC and TK of NZ2114 was evaluated against staphylococci (STA) and streptococci (STR) including clinically relevant resistant (R) phenotypes. Methods: The MIC and MBC of NZ2114 against 9 S. aureus (SA), 7 coagulase-negative STA (CNS), 5 S. pneumoniae, and 10 β-hemolytic STR with relevant R phenotypes was determined (CLSI M7-A7; CLSI M26-A; MBC defined as the concentration where a ≥ 3-log10 kill was observed). TK of NZ2114 were evaluated at 2X, 4X, and 8X the MIC against 7 SA (including methicillin-R clones [e.g. USA300/100] and vancomycin non-susceptible isolates), 1 methicillin-R S. epidermidis (SE), and ATCC strains of S. pneumoniae and S. pyogenes. Viability was assessed periodically over a 24 hour period and cidal activity was defined as ≥ 3-log10 reduction in CFU at 24 hr (CLSI M26-A). Results: NZ2114 MBC:MIC ratios ranged from 1-2 against all STA and STR regardless of phenotype, excluding 1 penicillin-R S. pneumoniae (MBC:MIC ratio >4). Cidality of NZ2114 against SA (including MRSA, VISA/VRSA) occurred within 2-6 hr at concentrations at 4X the MIC and 2X the MIC in some instances, with the exception of the tested VISA where cidality was observed only at 8X the MIC. Cidality of NZ2114 was also observed against methicillin-R SE at 2X the MIC (as early as 3 hr), and against S. pneumoniae and S. pyogenes at 4X and 2X the MIC, respectively, with a 3-log kill as early as 1 hr. Conclusions: NZ2114 was cidal by MBC (MBC:MIC ratios of ≤2) against STA and STR regardless of resistance. This cidality was validated by TK which included a variety of prevalent R clones of SA. The rapid bactericidal activity of NZ2114 against STR and STA, including prevalent R isolates, highlights the potential of NZ2114 as a cidal agent for the treatment of GP infections involving STR and STA.
[Show abstract][Hide abstract] ABSTRACT: Background: Arenicin-3 is an antimicrobial peptide isolated using Transposon-Assisted-Signal -Trapping from the lugworm Arenicola marina living on sediments in the tidal water.
Structural analysis showed that Arenicin-3 belonged to the beta-hairpin peptides. This class of AMPs are known to exhibit cidal activities towards a diverse number of microorganisms. Interestingly, susceptibility data on clinical isolates of Klebsiella pneumoniae, Salmonella enterica, Pseudomonas aeruginosa and Escherichia coli showed very potent activities of Arenicin. Methods: Minimal inhibitory concentrations were performed according to the general guidelines for susceptibility measurements using micro-broth dilution provided by CLSI/ NCCLS (M7-A5)
All isolates were tested by a standard time-kill methodology as described by CLSI document M26-A: Methods for Determining Bactericidal Activity of Antimicrobial Agents; approved guideline, with the exception of taking earlier time points than normal due to the rapid bactericidal nature of Arenicin-3. Results: Gram-negative bacteria including multi-resistant clinical relevant isolates of Escherichia coli, Klebsiella pneumoniae, Salmonella Typhimurium, Pseudomonas aeruginosa and Stenotrophomonas maltophilia were susceptibility tested to Arenicin-3. The results for isolates of both Enterobactericeae (n=148) and non fermentors (n=53) populations, MIC90 was < 1 mg/ml. The antimicrobial activity is markedly bactericidal (MBC~1-4xMIC), causing 3-log (99.9%) reduction in the viable bacteria population within 1-2 hours of Arenicin-3 exposure. Conclusions: Arenicin-3 has shown potential antimicrobial activity, even against multi resistant clinical isolates (ESBL positive, fluoroquinolone resistant, aminoglycoside resistant)
[Show abstract][Hide abstract] ABSTRACT: Background: NZ2114 is a plectasin analogue active against Gram-positive (GP) cocci currently being developed for the potential treatment of sepsis, upper respiratory infections, skin and soft tissue infections, pneumonia, and tonsillitis. Staphylococci (STA) and streptococci (STR) are major pathogens of these types of infections. The activity of NZ2114 was evaluated against these organisms, including isolates with clinically relevant resistance. Methods: Clinical isolates including 121 Staphylococcus aureus (SA), 50 coagulase-negative staphylococci (CoNS), 50 Streptococcus pneumoniae (SP), 51 Group C and G streptococci (GCG), 45 S. agalactiae (SAG), and 50 S. pyogenes (SPY) were centrally tested by broth microdilution (CLSI M7-A7) against NZ2114 and comparators. Isolates resistant (R) or non-susceptible (NS) to oxacillin (OX), penicillin (PEN), or a macrolide (MAC) were included. Additional SA NS to vancomycin (VAN), linezolid (LZD), and/or daptomycin (DAP) from the NARSA or Eurofins repository were also analyzed.
Conclusions: NZ2114 displayed potent in vitro activity against both STA and STR. Based on MIC50/MIC90, NZ2114 had similar activity (within one doubling dilution) against OX-R STA and PEN-R/MAC-NS STR populations relative to susceptible populations. Activity was also apparent against LZD/DAP/VAN-NS populations of SA, though NZ2114 MICs tended to be slightly higher against the evaluated VISA. This activity profile highlights the potential of NZ2114 for infections where STR and STA are commonly encountered.
Chris Pillar, PhD1, D Sandvang, PhD2, Daniel Sahm, PhD3, Deborah Draghi, BS4, H Kristensen, PhD2, Mohana Torres, BS1, Nina Brown, MS5 and M. K. Torres, None., (1)Eurofins Medinet, Herndon, VA, (2)Novozymes, (3)Eurofins Medinet, Inc., Anti-Infective Services, Herndon, VA, (4)Eurofins Medinet, Inc., Herndon, VA, (5)Eurofins Medinet, Chantilly, VA
[Show abstract][Hide abstract] ABSTRACT: Background: Plectasin is the first defensin-type antimicrobial peptide isolated from a fungus and has potent activity against Gram-positive bacteria; however pk/pd properties of the plectasin variant NZ2114 in local infections still remain to be defined. Methods: Using a rabbit meningitis model, the CSF penetration and bactericidal activity of NZ2114 and ceftriaxone against a penicillin-resistant Streptococcus pneumoniae (NZ2114 and ceftriaxone MICs: 0.25 and 0.5 µg/ml, respectively) was studied. Results: Pharmacokinetics: There was a significant higher CSF penetration of NZ2114 through inflamed - compared to noninflamed meninges (AUCCSF/serum: 32% vs. 2%, respectively). CSF conc. peaked at ~3 hours after an iv. infusion of either 20 or 40 mg/kg and remained above 10 x the MIC during a 6-hour study period. Bactericidal activity: Treatment with NZ2114 (40 and 20 mg/kg at 0 and 5 hours, respectively, n=11) caused a significantly higher reduction in CSF bacterial concentrations (delta Log10 CFU/mL) as compared to therapy with ceftriaxone (125 mg/kg at 0 hours, n=7) at 3 hours (median: 3.7 (interquartile range: 2.5-4.6) vs. 2.1 (1.7-2.6), respectively, Mann Whitney test, P=0.001), at 5 hours (5.2 (3.6-6.1) vs. 3.1 (2.6-3.7), respectively, P=0.01) and at 10 hours (5.6 (5.2-5.9) vs. 4.2 (3.6-5.0), respectively, P=0.03) after start of therapy as well as compared to untreated meningitis rabbits (n=7, P<0.05, data not shown). Also, significant more rabbits had sterile CSF at 5 and 10 hours, when treated with NZ2114 as compared to therapy with ceftriaxone (5/9 vs. 0/7 and 6/8 vs. 1/7, respectively, Fisher Exact test, P<0.05). Conclusions: Due to its excellent CSF penetration and potent CSF bactericidal activity, the plectasin variant NZ2114 could be a new promising treatment option of Gram-positive CNS infections, including penicillin-resistant pneumococcal meningitis.
[Show abstract][Hide abstract] ABSTRACT: Background Ampicillin-resistant Enterococcus faecium isolates are reported in increasing numbers in many European hospitals. The clonal complex 17 (CC17) characterized by ampicillin resistance has been associated with nosocomial E. faecium outbreaks and infections in five continents. The aim was to investigate how prevalent ampicillin resistance is in clinical E. faecium isolates from Denmark and to investigate their clonal affiliation, especially to CC17. Methods Microbiology data from 2002 through 2006 on E. faecium and Enterococcus faecalis blood isolates was received from Departments of Clinical Microbiology in 11 Danish counties. From January 2004 through December 2004, we collected 275 clinical enterococci from four of these departments. Multilocus sequence typing (MLST) and PFGE were performed on the 84 ampicillin-resistant E. faecium isolates from this collection. Results A 68% increase in the number of infections caused by enterococci was observed from 2002 through 2006. The increase was mainly caused by E. faecium isolates, which tripled, whereas the number of E. faecalis isolates increased by only 23% during the same period. There was also a significant increase in the number of ampicillin-resistant E. faecium isolates. MLST showed that 98% of the tested ampicillin-resistant E. faecium isolates belonged to CC17. PFGE showed eight different clusters and we found indications of clonal spread within the hospitals. Conclusions Ampicillin-resistant E. faecium isolates have increased in frequency in Denmark during 2002-2006. Most of the ampicillin-resistant E. faecium isolates belong to complex CC17.
Full-text · Article · Oct 2008 · Journal of Antimicrobial Chemotherapy
[Show abstract][Hide abstract] ABSTRACT: The main purpose of the study was to investigate the frequency of ESBL-producing E. coli and Klebsiella strains in the Greater Copenhagen area. Four collections of strains were investigated: A) 380 consecutive E. coli and Klebsiella isolates primarily from urine, B) 200 gentamicin-resistant E. coli and Klebsiella isolates primarily from urine, C) 210 consecutive E. coli isolates from blood cultures, and D) 68 cefuroxime-resistant E. coli and Klebsiella isolates primarily from urine. Only one strain per patient was included. Strains with a zone diameter for cefpodoxime <or=23 mm were tested by a phenotypic confirmatory test for ESBL production and all screening test-positive strains were examined with PCR and nucleotide sequencing in order to detect the following ESBL genes: ctx-m, shv, tem and oxa. Strains resistant to cefoxitin were further examined with cefotetan+/-boronic acid in order to detect AmpC. An ESBL gene was detected in 3/3 confirmatory test-positive isolates from collection A, in 14/17 from collection B, and in 41/48 from collection D. The distribution of isolates with the ESBL and/or AmpC enzymes was as follows: CTX-M (n=41), SHV (n=14), AmpC (n=9), CTX-M and AmpC (n=2), SHV and AmpC (n=1). In conclusion, the frequency of ESBL-producing E. coli and Klebsiella isolates was low in the Copenhagen area of Denmark (0.8 %). The most common ESBL genes found in our study were ctx-m and shv genes.
[Show abstract][Hide abstract] ABSTRACT: The aim of the study was to investigate the potential spread of gentamicin resistant (GENR) Escherichia coli isolates or GENR determinants from a Danish university hospital to the waste water environment. Waste water samples were collected monthly from the outlets of the hospital bed wards and the inlet of the related waste water treatment plant (WWTP) from October 2002 to August 2003. Waste water samples were also collected monthly from a residential area in the same period to be able to compare the prevalence of GENRE. coli isolates from hospital related and residential waste water. The waste water isolates were compared to GENRE. coli isolates obtained consecutively from September 2002 to September 2003 from patients mainly with urinary tract infections at the hospital with respect to Pulsed Field Gel Electrophoresis (PFGE) profiles. All isolates were investigated for GENR mechanisms (aac(3)-II, aac(3)-IV, ant(2″)-I, armA), phenotypic resistance pattern, and virulence genes (hlyA, chuA, sfaS, fogG, malX, traT, iutA, fyuA, iroN, cnf1) to investigate if the hospital and waste water could be reservoirs of antimicrobial resistance and virulence. The ability for GENR determinants to transfer horizontally was investigated by mating experiments.
Full-text · Article · Feb 2008 · Environment International
[Show abstract][Hide abstract] ABSTRACT: Escherichia coli isolates obtained from faeces (n=85) and blood (n=123) were susceptibility tested against 17 antimicrobial agents and the presence of 9 virulence genes was determined by PCR. Positive associations between several antimicrobial resistances and 2 VF genes (iutA and traT) were found among blood isolates, sometimes among faecal isolates.
No preview · Article · Feb 2007 · Infectious Diseases
[Show abstract][Hide abstract] ABSTRACT: The primary infecting Escherichia coli strains from 156 women with community-acquired uncomplicated urinary tract infection (UTI) randomized to pivmecillinam or
placebo and the E. coli strains causing UTI at two follow-up visits were typed using pulsed-field gel electrophoresis (PFGE). In the pivmecillinam
treatment group PFGE showed that among patients having a negative urine culture at the first follow-up 77% (46/60) had a relapse
with the primary infecting E. coli strain and 23% (14/60) had reinfection with a new E. coli strain at the second follow-up. Among patients having E. coli at the first follow-up PFGE showed that 80% (32/40) had persistence with the primary infecting E. coli strain, 15% (6/40) had reinfection with a new E. coli strain, and 5% (2/40) had different E. coli strains at the two follow-up visits (one had reinfection followed by relapse, and the other had persistence followed by reinfection).
In the placebo group the majority had E. coli at the first follow-up. PFGE showed that among these patients 96% (50/52) had persistence with the primary infecting E. coli strain and 4% (2/50) had different E. coli strains at the two follow-up visits (both had persistence followed by reinfection). The finding that the majority of UTIs
at follow-up are caused by the primary infecting E. coli strain supports the theory of a vaginal and rectal reservoir but could also support the recent discovery that E. coli strains are able to persist in the bladder epithelium despite appropriate antibiotic treatment, constituting a reservoir
for recurrent UTI.
Full-text · Article · Jun 2006 · Journal of Clinical Microbiology
[Show abstract][Hide abstract] ABSTRACT: The occurrence of sulphonamide resistance was investigated in 998 Escherichia coli isolates, obtained from pig faeces collected at slaughter, Danish pork collected at retail outlets and from faeces from healthy persons in Denmark. In total 18% (n=35), 20% (n=38) and 26% (n=161) of the E. coli isolates obtained from humans, pork and pigs, respectively, were resistant to sulphonamide. All sulphonamide resistant E. coli isolates were investigated for the presence of sul1, sul2, sul3 and intI1 genes by PCR. The sul1 gene was detected in 40% (n=14), 29% (n=11) and 55% (n=88) of the sulphonamide resistant isolates from humans, pork and pigs, respectively. The sul2 gene was detected in 80% (n=28), 76% (n=29) and 50% (n=81) of isolates from humans, pork and pigs, respectively. None of the human isolates were PCR-positive for sul3, whereas sul3 was present in 5% of the pork isolates and 11% of the pig isolates. Of the 113 sul1 positive isolates, 97 carried the integron-associated integrase gene intI1. All 20 sul3 positive isolates were positive for intI1, and in 12 of these isolates sul3 was the only sulphonamide resistance gene detected. The origin of sul1 and sul2 found in isolates from healthy humans is speculative, but their spread from pigs to humans via the food chain is possible.
Full-text · Article · Mar 2006 · International Journal of Food Microbiology
[Show abstract][Hide abstract] ABSTRACT: Fifty-seven Salmonella Typhimurium strains isolated from poultry, swine and animal feed in Poland during the years 1979-1998 and 2000-2002 were analysed with conventional and molecular techniques. Antimicrobial resistance as well as multiresistance was found, respectively, in 80.1% and 56.1% of the isolates and most frequently among isolates from 2000-2002. Of several phage types noted, DT104 was prevalent among poultry, swine and feed isolates. DT104, U302 and non-typable strains had a multiple resistant profile (ACSSuT) due to the presence of class I integrons. Pulse-field gel electrophoresis of XbaI and BlnI digest showed high genomic similarity between the strains and confirmed clonal spread of S. Typhimurium infections. Plasmid profiling allowed further differentiation of the strains. We have, therefore, confirmed the appearance of S. Typhimurium DT104 showing genome integrated integron-mediated antimicrobial resistance in Poland. These findings are significant for public and animal health risks and document the dissemination of DT104 epidemic strains into new geographical regions.
Full-text · Article · Mar 2006 · Epidemiology and Infection
[Show abstract][Hide abstract] ABSTRACT: To test the bactericidal activity of human beta-defensins (hBDs) 2 and 3 against extended-spectrum beta-lactamase (ESBL)-producing Klebsiella strains.
Thirty-six Klebsiella pneumoniae and seventeen Klebsiella oxytoca ESBL-producing isolates from nosocomial infections were tested. The bactericidal activity of recombinantly synthesized hBD-2 and -3 was tested and the results were given either as lethal doses killing > or = 90% of bacteria (LD90s) or as MBCs (> or = 99.9% killing).
Except for one intermediately susceptible strain (MBC = 25 mg/L), all other ESBL-producing strains were highly susceptible to both defensins (LD90s and MBCs < or = 12.5 mg/L).
The results underline the high efficacy of hBD-2 and -3 against ESBL-producing Klebsiella, making both defensins attractive candidates as antimicrobial agents to combat these increasingly troublesome bacteria.
Full-text · Article · Mar 2006 · Journal of Antimicrobial Chemotherapy
[Show abstract][Hide abstract] ABSTRACT: The presence of tetracycline resistance (Tcr) genes and class I integrons (in-1), and their ability to cotransfer were investigated in Tcr gram-negative (185 strains) and gram-positive (72 strains) bacteria from Danish farmland and pigsties. The isolates belonged
to the groups or species Escherichia coli, Enterobacter spp., Arthrobacter spp., Alcaligenes spp., Pseudomonas spp., and Corynebacterium glutamicum. The 257 isolates were screened for in-1. Eighty-one of the gram-negative isolates were also screened for the Tcr genes tet(A), tet(B), and tet(C), and all (n = 72) gram-positive isolates were screened for tet(33). Fourteen (7%) of the soil isolates and eleven (25%) of the pigsty isolates contained in-1. All isolates that contained
tet genes also contained in-1, except one gram-negative isolate from a pigsty that contained tet(B). All gram-positive isolates with in-1 also contained tet(33). No isolates contained more than one tet gene. The in-1-positive isolates were tested for resistance to selected antimicrobial agents and showed resistance to three
to nine drugs. Filter-mating experiments showed cotransfer of Tcr and class I integrons from soil isolates to Escherichia coli and/or Pseudomonas putida. We conclude that soil bacteria in close contact to manure or pigsty environment may thus have an important role in horizontal
spread of resistance. Use of tetracyclines in food animal production may increase not only Tcr but also multidrug resistance (caused by the presence tet genes and in-1) in bacteria.
Preview · Article · Jan 2006 · Applied and Environmental Microbiology
[Show abstract][Hide abstract] ABSTRACT: OBJECTIVES: To test the bactericidal activity of human beta-defensins (hBDs) 2 and 3 against extended-spectrum beta-lactamase (ESBL)-producing Klebsiella strains.
METHODS: Thirty-six Klebsiella pneumoniae and seventeen Klebsiella oxytoca ESBL-producing isolates from nosocomial infections were tested. The bactericidal activity of recombinantly synthesized hBD-2 and -3 was tested and the results were given either as lethal doses killing > or = 90% of bacteria (LD90s) or as MBCs (> or = 99.9% killing).
RESULTS: Except for one intermediately susceptible strain (MBC = 25 mg/L), all other ESBL-producing strains were highly susceptible to both defensins (LD90s and MBCs < or = 12.5 mg/L).
CONCLUSIONS: The results underline the high efficacy of hBD-2 and -3 against ESBL-producing Klebsiella, making both defensins attractive candidates as antimicrobial agents to combat these increasingly troublesome bacteria.
Full-text · Article · Jan 2006 · Journal of Antimicrobial Chemotherapy
[Show abstract][Hide abstract] ABSTRACT: Molecular typing is an important tool in surveillance and outbreak investigations of human Salmonella infections. In this study, three molecular typing methods were used to investigate the discriminatory ability, reproducibility and the genetic relationship between 110 Salmonella enterica subspecies enterica isolates. A total of 25 serotypes were investigated that had been isolated from humans or veterinary sources in Denmark between 1995 and 2001. All isolates were genotyped by multilocus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE) and amplified fragment length polymorphism (AFLP). When making genetic trees, all three methods resulted in similar clustering that often corresponded with serotype, although some serotypes displayed more diversity than others. Of the three techniques, MLST was the easiest to interpret and compare between laboratories. Unfortunately the seven housekeeping genes used in this MLST scheme lacked diversity and the ability to discriminate between isolates were higher with both PFGE and AFLP. The discriminatory power of AFLP and PFGE were similar but PFGE fingerprints were both easier to reproduce, interpret and less time-consuming to analyze when compared to AFLP. PFGE is the therefore the preferred molecular typing method for surveillance and outbreak investigations, whereas AFLP is most useful for local outbreak investigations.
No preview · Article · Dec 2005 · Journal of Microbiological Methods