Prevalence and diversity of class 1 integrons and resistance genes in antimicrobial-resistant Escherichia coli originating from beef cattle administered subtherapeutic antimicrobials

Aims: To characterize class 1 integrons and resistance genes in tetracycline‐resistant Escherichia coli originating from beef cattle subtherapeutically administered chlortetracycline (A44), chlortetracycline and sulfamethazine (AS700), or no antimicrobials (control). Methods and Results: Tetracycline‐resistant E. coli (control, n = 111; AS700, n = 53; A44, n = 40) were studied. Class 1 integrons, inserted gene cassettes and the presence of other antimicrobial resistance genes, as well as phylogenetic analysis, were performed by PCR, restriction enzyme analysis and sequencing. Susceptibilities to 11 antimicrobials were conducted on all isolates. Prevalence of class 1 integrase was higher (P < 0·001) in isolates from AS700 (33%) and A44 (28%) steers as compared to control (7%). Most integron gene cassettes belonged to the aad or dfr families. Correlations were found between the tet(A) gene and the genetic elements sul1 (r = 0·44), aadA1 (r = 0·61), cat (r = 0·58) and intI1(r = 0·37). Both closely and distantly related isolates harboured integrons with identical gene cassette arrays. Conclusions: Subtherapeutic administration of chlorotetracycline alone or in combination with sulfamethazine may select for class 1 integrons in bovine tetracycline‐resistant E. coli isolates. Vertical spread and horizontal transfer are responsible for the dissemination of a particular type of class 1 integron, but this study could not differentiate if this phenomenon occurred within or outside of the feedlot. Tetracycline‐resistant E. coli strains with sul1 and tet(A) genes were more likely to harbour class 1 integrons. Significance and Impact of the Study: Subtherapeutic use of chlortetracycline and sulfamethazine may promote the presence of class 1 integrons in tetracycline‐resistant E. coli isolated from feedlot cattle.     

Occurrence and molecular characteristics of antimicrobial resistance of Escherichia coli from broilers,pigs and meat products in Thailand and Cambodia provinces

Nine hundred and forty‐one samples were collected in Sa Keao, Thailand (n = 554) and Banteay Meanchey, Cambodia (n = 387) from July 2014 to January 2015. A total of 667 Escherichia coli isolates (381 isolates from Sa Keao and 286 isolates from Banteay Meanchey) were obtained and examined for antimicrobial susceptibility, class 1 integrons, ESBL genes and horizontal transfer of resistance determinants. Prevalence of E. coli in pig and broiler carcass samples from slaughterhouses and fresh markets was 36–85% in Sa Keao and 11–69% in Banteay Meanchey. The majority of these isolates were multidrug resistant (75.3%). Class 1 integrons were common in both Thai (47%) and Cambodian (62%) isolates, of which four resistance gene cassette arrays including aadA1, dfrA1‐aadA1, dfrA12‐aadA2 and aadA2‐linF were identified. Class 1 integrons in two broiler isolates from Sa Keao (dfrA12‐aadA2) and one broiler isolate from Banteay Meanchey (dfrA1‐aadA1) were horizontally transferable. Sixteen isolates were confirmed to be ESBL‐producing strains with ESBL gene bla_CTX‐M‐15, broad spectrum β‐lactamase gene bla_TEM‐1 and the AmpC gene bla_CMY‐2 being detected. The bla_TEM‐1 gene was most prevalent and located on a conjugative plasmid.     

Antibiotic resistance patterns and sequencing of class I integron from uropathogenic Escherichia coli in Lebanon

Aim: To study the prevalence and molecular basis of antimicrobial resistance in UPEC. Methods and Results: PCR was used to detect the presence of the Class I integron variable region (VR). The VR amplicons were then characterized by partial sequencing and restriction digestion with AluI. VR negative isolates showed more antibiotic susceptibility than VR positive isolates. 30% of the isolates were positive for the VR and carried the genes dfrA7, dfrA17‐aadA5, dfrA1‐aadA1, dfrA12‐orf5‐aadA2 and bla_OXA‐30‐aadA1. Five restriction patterns were detected and isolates with the same VR amplicon size had the same restriction pattern. Conclusions: Our data demonstrated that Class I integrons are widely disseminated in Lebanon and showed their importance for the occurrence and transmission of multidrug resistance. Significance and Impact of the Study: These findings will facilitate greater understanding of the factors that contribute to the presence and transfer of integron‐associated antibiotic resistance genes in UPEC.     

Phenotypic and genetic characterization of multidrug-resistant <Emphasis Type="Italic">Salmonella</Emphasis> Infantis strains isolated from broiler chicken meats in Turkey

Twenty Salmonella Infantis strains resistant against kanamycin, tetracycline, neomycin, spectinomycin, sulphonamide, nalidixic acid and trimethoprim were selected for this study out of 103 Salmonella strains isolated from broiler samples collected from several markets in the Bolu and Ankara regions of Turkey. The resistance genes aadA1, aphA1, sul1, tet(A), dfrA5/dfrA14 and gyrA were determined for these multidrug-resistant S. Infantis strains. S. Infantis strains contained a mega plasmid with the molecular size of 206 kb. The strains were divided into three groups according to the pulsed field gel electrophoresis patterns of XbaI digested chromosomal DNA. A Ser83→Tyr83 point mutation was found in the gyrA gene of all quinolone-resistant isolates. Filter mating experiments showed that 206 kb plasmid transferred nalidixic acid resistance associated with class I integrons.     

Class 1 and class 2 integrons and plasmid-mediated antibiotic resistance in coliforms isolated from ten rivers in northern Turkey

We aimed to determine the molecular mechanisms of antibiotic resistance in coliforms isolated from ten rivers in northern region of Turkey. A total of 183 isolates were tested for antimicrobial susceptibility by disk diffusion and agar dilution methods. Resistance to ampicillin, streptomycin, trimethoprim, tetracycline, and chloramphenicol was detected in 58%, 51.9%, 24%, 28.4%, and 12.5%, respectively. Twelve (6.5%) phylogenetically distant organisms were detected to harbor self-transmissible plasmids ranging 52 to >147 kb in sizes. Resistances to ampicillin, tetracycline, trimethoprim, streptomycin, and nalidixic acid were commonly transferable traits. Transferable nalidixic acid-resistant strains harbored qnrS gene, which was the first report of plasmid-mediated quinolone resistance in bacteria of environmental origin in Turkey. Fourteen and five coliforms harbored class 1 and class 2 integrons, respectively, and some of them were located on transferable plasmids. Sequence analyses of variable regions of the class 1 and 2 integrons harbored various gene cassettes, dfrA1, dfr2d, dfrA7, dfrA16, dfrA17, aadA1, aadA5, bla _oxA-30, and sat1. A gene cassette array, dfrA16 has been demonstrated for the first time in a Citrobacter koseri isolate. Class 1 and class 2-bearing strains were clustered in different groups by BOX-PCR fingerprinting. Rivers in the northern Turkey may act as receptacle for the multi-drug resistant enterobacteria and can serve as reservoirs of the antimicrobial resistance determinants in the environment. The actual risk to public health is the transfer of resistance genes from the environmental bacteria to human pathogens. This study was presented in part at the 2^nd World Conference on Magic Bullets, held October 3–5, 2008 in Nurnberg, Germany.     

Prevalence and antimicrobial resistance in Salmonella enterica isolated from broiler chickens,pigs and meat products in Thailand–Cambodia border provinces

This study aimed to examine the prevalence and antimicrobial resistance (AMR) of Salmonella isolates from broiler chickens, pigs and their associated meat products in the Thailand–Cambodia border provinces. A total of 941 samples were collected from pigs and broiler chickens at slaughter houses and from carcasses at local fresh markets in Sa Kaeo, Thailand (n = 554) and Banteay Meanchey, Cambodia (n = 387) in 2014 and 2015. From these samples, 345 Salmonella isolates were collected from Sa Keao (n = 145; 23%) and Banteay Meanchey (n = 200; 47%) and assayed for antimicrobial susceptibility, class 1 integrons and extended‐spectrum β‐lactamase (ESBL) genes. Serovars Typhimurium (29%) and Rissen (29%) were the most common serotypes found in Thai and Cambodian isolates, respectively. Multidrug resistance was detected in 34% and 52% of isolates from Sa Keao and Banteay Meanchey, respectively. The majority of the Thai isolates were resistant to ampicillin (72.4%), whereas most Cambodian isolates were resistant to sulfamethoxazole (71%). Eleven isolates from Sa Keao and 44 from Banteay Meanchey carried class 1 integrons comprising resistance gene cassettes. The most common gene cassette array was dfrA12‐aadA2 (61.1%). Six isolates were ESBL producers. The β‐lactamase genes found included bla_TEM‐1, bla_CTX‐M‐55 and bla_CMY‐2. Some of these class 1 integrons and ESBL genes were located on conjugative plasmid. In conclusion, multidrug‐resistant Salmonella are common in pigs, chickens and their products in the Thailand–Cambodia border provinces. Our findings indicate that class 1 integrons play a role in spread of AMR in the strains in this study.     

A set of novel multiplex Taqman real-time PCRs for the detection of diarrhoeagenic Escherichia coli and its use in determining the prevalence of EPEC and EAEC in a university hospital

Background

Escherichia coli isolates of equine faecal origin were investigated for antibiotic resistance, resistance genes and their ability to perform horizontal transfer.

Methods

In total, 264 faecal samples were collected from 138 horses in hospital and community livery premises in northwest England, yielding 296 resistant E. coli isolates. Isolates were tested for susceptibility to antimicrobial drugs by disc diffusion and agar dilution methods in order to determine minimum inhibitory concentrations (MIC). PCR amplification was used to detect genes conferring resistance to: ampicillin (TEM and SHV beta-lactamase), chloramphenicol (catI, catII, catIII and cml), tetracycline (tetA, tetB, tetC, tetD, tet E and tetG), and trimethoprim (dfrA1, dfrA9, dfrA12, dfrA13, dfr7, and dfr17).

Results

The proportion of antibiotic resistant isolates, and multidrug resistant isolates (MDR) was significantly higher in hospital samples compared to livery samples (MDR: 48% of hospital isolates; 12% of livery isolates, p < 0.001). Resistance to ciprofloxacin and florfenicol were identified mostly within the MDR phenotypes. Resistance genes included dfr, TEM beta-lactamase, tet and cat, conferring resistance to trimethoprim, ampicillin, tetracycline and chloramphenicol, respectively. Within each antimicrobial resistance group, these genes occurred at frequencies of 93% (260/279), 91%, 86.8% and 73.5%, respectively; with 115/296 (38.8%) found to be MDR isolates. Conjugation experiments were performed on selected isolates and MDR phenotypes were readily transferred.

Conclusions

Our findings demonstrate that E. coli of equine faecal origin are commonly resistant to antibiotics used in human and veterinary medicine. Furthermore, our results suggest that most antibiotic resistance observed in equine E. coli is encoded by well-known and well-characterized resistant genes common to E. coli from man and domestic animals. These data support the ongoing concern about antimicrobial resistance, MDR, antimicrobial use in veterinary medicine and the zoonotic risk that horses could potentially pose to public health.     

Antimicrobial susceptibilities and resistance genes in Campylobacter strains isolated from poultry and pigs in Australia

Aims

To evaluate the phenotypic and genotypic profiles of Campylobacter spp. from poultry faecal samples from free range or intensively raised meat chickens and free range egg layers. In addition, a case‐comparison study of antibiotic resistance genes from different groups of poultry and some pig strains previously collected was carried out.

Methods

Resistance to different antibiotics was assessed using the agar dilution method. In addition, all the strains were tested for ampicillin (bla_OXA‐61), erythromycin (aph‐3‐1), tetracycline tet(O), streptomycin (aadE), and the energy‐dependent multi‐drug efflux pump (cmeB) resistance genes using multiplex polymerase chain reaction.

Results

The evaluation of phenotypic resistance revealed all of the strains from poultry were sensitive to ciprofloxacin, gentamicin, erythromycin or tylosin. But, widespread resistance to lincomycin (51–100%), extensive resistance to ampicillin (33·3–60·2%) and less resistance to tetracycline (5·6–40·7%) were observed in the different groups of chickens. Antibiotic resistance genes bla_OXA‐61, cmeB and tet(O) were found in 82·6–92·7%, 80·3–89% and 22·3–30·9% Camp. coli isolates from pigs, whilst 59–65·4% and 19·2–40·7% Camp. jejuni from chickens were found to encode bla_OXA‐61 and tet(O), respectively.

Conclusion

No significant difference between isolates from free range egg layers and meat chickens (P < 0·05) was found. However, there were significant differences between the pig strains and all the groups of poultry strains (P < 0·05) with regard to carriage of resistance genes. In addition, pulsed field gel electrophoresis of selected resistant isolates from the poultry and pig revealed closely related clonal groups.

Significance and Impact of the study

Our results suggest the resistant strains are persisting environmental isolates that have been acquired by the different livestock species. Furthermore, the different treatment practices in poultry and pigs have resulted in differences in resistance profiles in Campylobacter isolates.     

Molecular characterization of multidrug-resistant Escherichia coli isolates from Irish cattle farms

This study describes the genotypic characteristics of a collection of 100 multidrug-resistant (MDR) Escherichia coli strains recovered from cattle and the farm environment in Ireland in 2007. The most prevalent antimicrobial resistance identified was to streptomycin (100%), followed by tetracycline (99%), sulfonamides (98%), ampicillin (82%), and neomycin (62%). Resistance was mediated predominantly by strA-strB (92%), tetA (67%), sul2 (90%), bla(TEM) (79%), and aphA1 (63%) gene markers, respectively. Twenty-seven isolates harbored a class 1 integrase (intI1), while qacEΔ1 and sul1 markers were identified in 25 and 26 isolates, respectively. The variable regions of these integrons contained aminoglycoside, trimethoprim, and β-lactam resistance determinants (aadA12, aadB-aadA1, bla(OXA-30)-aadA1, dfrA1-aadA1, dfrA7). Class 2 integrons were identified less frequently (4%) and contained the gene cassette array dfrA1-sat1-aadA1. Resistance to ampicillin, neomycin, streptomycin, sulfonamide, and tetracycline was associated with transferable high-molecular-weight plasmids, as demonstrated by conjugation assays. A panel of virulence markers was screened for by PCR, and genes identified included vt1, K5 in 2 isolates, papC in 10 isolates, and PAI IV(536) in 37 isolates. MDR commensal E. coli isolates from Irish cattle displayed considerable diversity with respect to the genes identified. Our findings highlight the importance of the commensal microflora of food-producing animals as a reservoir of transferable MDR.     

Antimicrobial resistance and class I integrons in Salmonella enterica isolates from wild boars and Bísaro pigs

The antibiotic resistance phenotype and genotype and the integron type were characterized in 58 Salmonella enterica isolates recovered from Bísaro pigs and wild boars (20 S. Typhimurium, 17 S. Rissen, 14 S. Enteritidis and 7 S. Havana). Most S. Typhimurium isolates (15/20 of Bísaro pigs and wild boars) showed ampicillin, chloramphenicol, streptomycin, tetracycline, sulfonamide, and amoxicillin-clavulanic acid resistances. Of the 17 S. Rissen isolates of both origins, 13 were resistant to ampicillin, tetracycline and trimethoprim-sulfamethoxazole. Among the S. Enteritidis isolates of Bísaro pigs, eight were nalidixic acid-resistant and three were sulfonamide-resistant. The tet(A) or tet(G) genes were detected in most tetracycline-resistant isolates. The intI1 gene was identified in 72.5% of S. enterica isolates in which the conserved region 3' of class 1 integrons (qacEΔ1+sul1) was also amplified, whereas none had the intI2 gene. The dfrA12+orfF+aadA2 gene cassette arrangement was found in the variable region of class 1 integrons in 14 S. Rissen isolates. Fifteen S. Typhimurium isolates had two integrons with variable regions of 1000 and 1200 bp that harbored the aadA2 and blaPSE-1 gene cassettes, respectively. In these isolates the floR and tet(G) genes were also amplified, indicative of the genomic island 1 (SGI1). Salmonella Typhimurium and S. Rissen of animal origin frequently show a multi-antimicrobial resistant phenotype, which may have implications in public health.     

Occurrence and transmission of class 1 and 2 integrons among phenotypic highly ampicillin-resistant avian <Emphasis Type="Italic">Escherichia coli</Emphasis> isolates from Pakistan

Thirty four avian Escherichia coli isolates were collected from different cities of Punjab province, Pakistan during 2008–2009. Twenty five phenotypic highly ampicillin-resistant (MICs ≥ 256 μg/ml) avian E. coli strains were selected for the investigation of occurrence and transmission of class 1, 2 and 3 integrons and β-lactamase genes. Amoxicillin, sulfonamide, trimethoprim, enrofloxacin, pefloxacin and tetracycline were the most common phenotypic resistant among ampicillin-resistant avian E. coli strains. Integrons and β-lactamase were found 60 and 72% respectively. Class 1 and 2 integrons were found 52 and 8%, while class 3 integrons were not found in all strains. All class 1 positive strains had variable fragments associated with gene cassettes dfrA7, dfrA1-aadA1, aadA1, aadA22 and dfrA12-orfF-aadA2 respectively, which confer resistance to trimethoprim and streptomycin. Class 2-positive strains had similar gene cassettes array dfrA1-sat1-aadA1 conferring resistance to trimethoprim, streptothricin and spectinomicin/streptomycin. Integrons are frequently found in β-lactamase positive isolates and widely disseminate multidrug resistance genes but they do not play role in the spreading of β-lactamase genes. Class 1 integrons gene cassette aadA22 is reported for the first time in avian E. coli. Findings of this study may provide important and useful information reflecting specific antibiotic selective pressure in Punjab province, Pakistan.     

Integron,Plasmid and Host Strain Characteristics of Escherichia coli from Humans and Food Included in the Norwegian Antimicrobial Resistance Monitoring Programs

Antimicrobial resistant Escherichia coli (n=331) isolates from humans with bloodstream infections were investigated for the presence of class 1 and class 2 integrons. The integron cassettes arrays were characterized and the findings were compared with data from similar investigations on resistant E. coli from meat and meat products (n=241) produced during the same time period. All isolates were obtained from the Norwegian monitoring programs for antimicrobial resistance in human pathogens and in the veterinary sector. Methods used included PCR, sequencing, conjugation experiments, plasmid replicon typing and subtyping, pulsed-field-gel-electrophoresis and serotyping. Integrons of class 1 and 2 occurred significantly more frequently among human isolates; 45.4% (95% CI: 39.9-50.9) than among isolates from meat; 18% (95% CI: 13.2 -23.3), (p<0.01, Chi-square test). Identical cassette arrays including dfrA1-aadA1, aadA1, dfrA12-orfF-aadA2, oxa-30-aadA1 (class 1 integrons) and dfrA1-sat1-aadA1 (class 2 integrons) were detected from both humans and meat. However, the most prevalent cassette array in human isolates, dfrA17-aadA5, did not occur in isolates from meat, suggesting a possible linkage between this class 1 integron and a subpopulation of E. coli adapted to a human host. The drfA1-aadA1 and aadA1 class 1 integrons were found frequently in both human and meat isolates. These isolates were subjected to further studies to investigate similarities with regard to transferability, plasmid and host strain characteristics. We detected incF plasmids with pMLST profile F24:A-:B1 carrying drfA1-aadA1 integrons in isolates from pork and in a more distantly related E. coli strain from a human with septicaemia. Furthermore, we showed that most of the class 1 integrons with aadA1 were located on incF plasmids with pMLST profile F51:A-:B10 in human isolates. The plasmid was present in unrelated as well as closely related host strains, demonstrating that dissemination of this integron also could be attributed to clonal spread. In conclusion, among the systematically collected isolates from two different sources, some significant differences concerning integron prevalence and integron variants were observed. However, closely related plasmids as vehicles for specific class 1 integrons in isolates from meat and from a human with bloodstream infection were found. The occurrence of similar multi-resistance plasmids in bacteria from a food source and from a human clinical sample highlights the possible role of meat as a source of resistance elements for pathogenic bacteria.     

Consistency in the host specificity and host sensitivity of the Bacteroides HF183 marker for sewage pollution tracking

Aims: The host specificity (H‐SPF) and host sensitivity (H‐SNV) values of the sewage‐associated HF183 Bacteroides marker in the current study were compared with the previously published studies in South East Queensland (SEQ), Australia, by testing a large number of wastewater and faecal DNA samples (n = 293) from 11 target and nontarget host groups. This was carried out to obtain information on the consistency in the H‐SPF and H‐SNV values of the HF183 marker for sewage pollution tracking in SEQ. Methods and Results: Polymerase chain reaction (PCR) analysis was used to determine the presence/absence of the HF183 marker in wastewater and faecal DNA samples. Among the human composite wastewater (n = 59) from sewage treatment plants and individual human (n = 20) faecal DNA samples tested, 75 (95%) were PCR positive for the HF183 marker. The overall H‐SNV of this marker in target host group was 0·95 (maximum of 1·00). Among the 214 nontarget animal faecal DNA samples tested, 201 (94%) samples were negative for the HF183 marker. Six chicken, five dog and two bird faecal DNA samples, however, were positive for the marker. The overall H‐SPF of the HF183 marker to differentiate between target and nontarget faecal DNA samples was 0·94 (maximum of 1·00). Conclusions: The H‐SNV (0·95) and H‐SPF (0·94) values obtained in this study was slightly lower than previous studies (H‐SNV value of 1·00 in 2007 and 1·00 in 2009; H‐SPF value of 1·00 in 2007 and 0·99 in 2009). Nonetheless, the overall high H‐SNV (0·98) and H‐SPF (0·97) values of the HF183 marker over the past 4 years (i.e. 2007–2011) suggest that the HF183 marker can be reliably used for the detection of sewage pollution in environmental waters in SEQ. Significance and Impact of the Study: In the current study, the HF183 marker was detected in small number nontarget animal faecal samples. Care should be taken to interpret results obtained from catchments or waterways that might be potentially contaminated with dog faecal matter or poultry litter.     

Characterization of multidrug-resistant Escherichia coli isolates from animals presenting at a university veterinary hospital

In this study, we examined molecular mechanisms associated with multidrug resistance (MDR) in a collection of Escherichia coli isolates recovered from hospitalized animals in Ireland. PCR and DNA sequencing were used to identify genes associated with resistance. Class 1 integrons were prevalent (94.6%) and contained gene cassettes recognized previously and implicated mainly in resistance to aminoglycosides, β-lactams, and trimethoprim (aadA1, dfrA1-aadA1, dfrA17-aadA5, dfrA12-orfF-aadA2, bla(OXA-30)-aadA1, aacC1-orf1-orf2-aadA1, dfr7). Class 2 integrons (13.5%) contained the dfrA1-sat1-aadA1 gene array. The most frequently occurring phenotypes included resistance to ampicillin (97.3%), chloramphenicol (75.4%), florfenicol (40.5%), gentamicin (54%), neomycin (43.2%), streptomycin (97.3%), sulfonamide (98.6%), and tetracycline (100%). The associated resistance determinants detected included bla(TEM), cat, floR, aadB, aphA1, strA-strB, sul2, and tet(B), respectively. The bla(CTX-M-2) gene, encoding an extended-spectrum β-lactamase (ESβL), and bla(CMY-2), encoding an AmpC-like enzyme, were identified in 8 and 18 isolates, respectively. The mobility of the resistance genes was demonstrated using conjugation assays with a representative selection of isolates. High-molecular-weight plasmids were found to be responsible for resistance to multiple antimicrobial compounds. The study demonstrated that animal-associated commensal E. coli isolates possess a diverse repertoire of transferable genetic determinants. Emergence of ESβLs and AmpC-like enzymes is particularly significant. To our knowledge, the bla(CTX-M-2) gene has not previously been reported in Ireland.     

Characterization of integrons and antimicrobial resistance genes in clinical isolates of Gram-negative bacteria from Palestinian hospitals

Sixty Gram-negative bacterial isolates were collected from Palestinian hospitals in 2006. Thirty-two (53.3%) isolates showed multidrug resistance phenotypes. PCR and DNA sequencing were used to characterize integrons and antimicrobial resistance genes. PCR screening showed that 19 (31.7%) and five (8.3%) isolates were positive for class 1 and class 2 integrons, respectively. DNA-sequencing results for the captured antimicrobial resistance gene cassettes within class 1 integrons identified the following genes: dihydrofolate reductases, dfrA1 , dfrA5 , dfrA7 , dfrA12, dfrA17 and dfrA25 ; aminoglycoside adenyltransferases, aadA1, aadA2 , aadA5, aadA12 and aadB ; aminoglycoside acetyltransferase, aac(6')-Ib ; and chloramphenicol resistance gene, cmlA1 . ESBL were identified in 25 (41.7%) isolates. The identified ESBL were bla _CTX-M-15, bla _CTX-M-56, bla _OXA-1, bla _SHV-1, bla _SHV-12, bla _SHV-32 and bla _TEM-1 genes. Moreover, we characterized the plasmid-mediated quinolone resistance genes, aac(6')-Ib-cr and qnrB2 , which were detected in seven (11.7%) and two (3.3%) isolates, respectively. In this study various types of antibiotic resistance genes have been identified in Gram-negative bacteria from Palestinian hospitals, many of which are reported in the Middle East area for the first time.     

Extended-spectrum beta-lactamase-producing Escherichia coli harbouring sul and mcr-1 genes isolates from fish gut contents in the Mekong Delta,Vietnam

This study investigated the existence of sulfonamides and colistin resistance genes among extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli recovered from fish gut in Vietnam and evaluated the susceptibility patterns of the ESBL-producing E. coli to relevant antimicrobials. A total of 88 ESBL-producing E. coli isolates were analysed for the presence of the ESBLs, sul (1, 2, 3) and mcr (1–3) genes by PCR. Antimicrobial resistance phenotypes of isolates were determined by disc diffusion. Results showed that: (i) A high prevalence of 94·3% of sulfonamide resistance was observed in 88 isolates. Moreover, the existence of 2·3% of ESBL-producing E. coli harbouring mcr-1 gene were detected; (ii) The phylogenetic types A and B1 were most frequent, and the bla_CTX-M group1 and bla_TEM genes encoding ESBL were detected in 47·7% of the isolates; (iii) ESBL-producing E. coli harbouring mcr-1 gene exhibited resistance to 11 antibiotics. The existence of mcr-1 and sul1,2,3 genes and the extremely high level of multiple drug resistance in all ESBL-producing E. coli isolates obtained from sampled fish in Vietnam is a major concern. Therefore, it is imperative to monitor ESBL-producing E. coli in the river waters of Vietnam.     

Escherichia coli and enterococci are sensitive and reliable indicators for human,livestock and wildlife faecal pollution in alpine mountainous water resources

Aims: This study evaluated the applicability of standard faecal indicator bacteria (SFIB) for alpine mountainous water resources monitoring. Methods and Results: Escherichia coli, enterococci (ENTC) and Clostridium perfringens were investigated by standard or frequently applied phenotypic and genotypic methods in a broad range of animal and human faecal sources in a large alpine mountainous area. Clostridium perfringens occurred only in human, livestock and carnivorous source groups in relevant average concentrations (log 4·7–7·0 CFU g^?1) but not in herbivorous wildlife sources. Escherichia coli proved to be distributed in all faecal source groups with remarkably balanced average concentrations (log 7·0–8·4 CFU g^?1). Except for single faecal samples from the cattle source group, prevalence rates for ENTC source groups were generally >87% with average concentrations of log 5·3–7·7 CFU g^?1. To test the faecal indication capacity in the environment, faecal prevalence data were comparatively analysed with results from the concurrently performed multi‐parametric microbial source tracking effort on karst spring water quality from the investigated alpine mountainous catchment ( Reischer et al. 2008 ; Environ Microbiol 10:2598–2608). Conclusion: Escherichia coli and enterococci are reliable faecal indicators for alpine mountainous water resources monitoring, although E. coli is the more sensitive one. Clostridium perfringens did not prove to be an indicator of general faecal pollution but is suggested a conservative microbial source tracking marker for anthropogenic faecal influence. Significance and Impact of the Study: Applicability of SFIB is currently hotly debated. This is the first study providing comprehensive information on the applicability of SFIB at alpine mountainous habitats.