Comparison of broad-spectrum cephalosporin-resistant Escherichia coli isolated from dogs and humans in Hokkaido, Japan

Current status and future perspective of antimicrobial-resistant bacteria and resistance genes in animal-breeding environments

The emergence and spread of antimicrobial-resistant bacteria (ARB) and antimicrobial resistance genes (ARGs) are a global public health concern. ARB are transmitted directly or indirectly from animals to humans. The importance of environmental transmission of ARB and ARGs has recently been demonstrated, given the relationships between compost, livestock wastewater, insects, and wildlife. In addition, companion animals and their surrounding environments (veterinary hospitals and homes with companion animals) should be considered owing to their close relationship with humans. This review discusses the current status and future perspectives of ARB and ARGs in animal-breeding environments.

Isolation of Human Lineage, Fluoroquinolone-Resistant and Extended-β-Lactamase-Producing Escherichia coli Isolates from Companion Animals in Japan

An increase in human and veterinary fluoroquinolone-resistant Escherichia coli is a global concern. In this study, we isolated fluoroquinolone-resistant E. coli isolates from companion animals and characterized them using molecular epidemiological analysis, multiplex polymerase chain reaction to detect E. coli ST131 and CTX-M type extended-spectrum β-lactamases (ESBL), and multi-locus sequence typing analysis. Using plain-CHROMagar ECC, 101 E. coli isolates were isolated from 34 rectal swabs of dogs and cats. The prevalence of resistance to fluoroquinolone and cefotaxime was 27.7% and 24.8%, respectively. The prevalence of fluoroquinolone-resistant isolates (89.3%) was higher when CHROMagar ECC with CHROMagar ESBL supplement was used for E. coli isolation. The prevalence of cefotaxime resistance was also higher (76.1%) when 1 mg/L of ciprofloxacin-containing CHROMagar ECC was used for isolation. The cefotaxime-resistant isolates possessed CTX-M type β-lactamase genes (CTX-M-14, CTX-M-15, or CTX-M-27). Seventy-five percent of fluoroquinolone-resistant isolates were sequence types ST131, ST10, ST1193, ST38, or ST648, which are associated with extensive spread in human clinical settings. In addition, we isolated three common fluoroquinolone-resistant E. coli lineages (ST131 clade C1-M-27, C1-nM27 and ST2380) from dogs and their respective owners. These observations suggest that companion animals can harbor fluoroquinolone-resistant and/or ESBL-producing E. coli, in their rectums, and that transmission of these isolates to their owners can occur.

Global prevalence and molecular characterization of extended-spectrum β-lactamase producing-Escherichia coli in dogs and cats - A scoping review and meta-analysis

Antimicrobial resistance (AMR) represents a major threat to human and animal health. Part of the AMR dimension is the circulation of extended-spectrum β-lactamases producing-Escherichia coli (ESBL-E. coli), which is now commonly reported among companion animals. However, the global perspective of the prevalence and population structure of ESBL-E. coli circulating in dogs and cats has not been estimated limiting our understanding of their role in the dissemination of ESBL-E. coli. The aim of this study was to compare the prevalence of ESBL-E. coli between dogs and cats and across countries through meta-analysis. We also performed a scoping review to summarize the current knowledge on ESBL genes and E. coli clones circulating among companion animals. A total of 128 studies published in PubMed, Web of Science, and Scopus up to April 2020 were selected and contained information on prevalence and/or molecular characterization of ESBL genes and ESBL-E. coli clones. Our review shows an increase in the number of publications between 2000 and 2019, concentrated mainly in Europe. Prevalence varied across continents, ranging from 0.63% (Oceania) to 16.56% (Africa) in dogs and from 0% (Oceania) to 16.82% (Asia) in cats. Although there were twice as many studies reporting prevalence on dogs (n = 61) than on cats (n = 32), and only 9 studies focused exclusively on cats, our meta-analysis showed no difference in the global prevalence of ESBL-E. coli between dogs (6.87% [95% CI: 4.46-10.45%]) and cats (5.04% [95% CI: 2.42-10.22%]). A considerable diversity of ESBL genes (n = 60) and sequence types (ST) (n = 171) were recovered from companion animals. ESBL-E. coli encoded by CTX-M-15 (67.5%, 77/114) and SHV-12 (21.9%, 25/114), along with resistant strains of ST38 (22.7%, 15/66) and ST131 (50%, 33/66) were widespread and detected in all continents. While presence of ESBL-E. coli is widespread, the drivers influencing the observed ESBL-E. coli prevalence and the clinical relevance in veterinary medicine and public health along with economic impact of ESBL-E. coli infections among companion animals need to be further investigated.

Association between the blaCTX-M-14-harboring Escherichia coli Isolated from Weasels and Domestic Animals Reared on a University Campus

Antimicrobial-resistant (AMR) bacteria affect human and animal health worldwide. Here, CTX-M-14-producing Escherichia coli isolates were isolated from Siberian weasels (Mustela sibirica) that were captured on a veterinary campus. To clarify the source of bacteria in the weasels, we examined the domestic animals reared in seven facilities on the campus. Extended-spectrum β-lactamase (ESBL)-producing E. coli were isolated on deoxycholate hydrogen sulfide lactose agar, containing cephalexin (50 μg/mL) or cefotaxime (2 μg/mL), and were characterized with antimicrobial susceptibility testing, pulsed-field gel electrophoresis (PFGE), replicon typing, and β-lactamase typing analyses. Next-generation sequencing of the ESBL-encoding plasmids was also performed. CTX-M-14 producers isolated from both domestic animals and weasels were classified into six clusters with seven PFGE profiles. The PFGE and antimicrobial resistance profiles were characterized by the animal facility. All CTX-M-14 plasmids belonged to the IncI1 type with a similar size (98.9-99.3 kb), except for one plasmid that was 105.5 kb in length. The unweighted pair group method with arithmetic mean (UPGMA) revealed that the CTX-M-14 plasmid in the weasel isolates might have the same origin as the CTX-M-14 plasmid in the domestic animals. Our findings shed further light on the association of antimicrobial resistance between wild and domestic animals.

Seven-year surveillance of the prevalence of antimicrobial-resistant Escherichia coli isolates, with a focus on ST131 clones, among healthy people in Osaka, Japan

OBJECTIVES

Escherichia coli (E. coli) is an indicator of antimicrobial resistance, and some strains of E. coli cause infectious diseases. E. coli sequence type 131 (ST131) - a global antimicrobial-resistant pandemic E. coli clone - is frequently detected in clinical specimens. Antimicrobial-resistant bacteria are monitored via national surveillance in clinical settings; however, monitoring information in non-clinical settings is limited. This study elucidated antimicrobial resistance trends of E. coli and dissemination of ST131 among healthy people in non-clinical settings.

METHODS

This study collected 517 E. coli isolates from healthy people in Osaka, Japan, between 2013 and 2019. It analysed antimicrobial susceptibility of the isolates and detected the bla and mcr genes in ampicillin-resistant and colistin-resistant isolates, respectively, and the ST131 clone.

RESULTS

Antimicrobial resistance rates of the bacteria isolated from healthy people in non-clinical settings were lower than for those in clinical settings. The resistance of the isolates to cefotaxime (4.4%) and ciprofloxacin (13.5%) gradually increased during the study period. In 23 cefotaxime-resistant isolates, the most frequent bla genes belonged to the bla_CTX-M-9 group, followed by bla_CTX-M-1 goup, bla_TEM and bla_CMY-2. One mcr-1-harbouring colistin-resistant isolate was detected in 2016. The incidence of the E. coli O25b-ST131 clone was approximately 5% until 2015 and 10% after 2016.

CONCLUSION

Both ciprofloxacin resistance and O25b-ST131 clone frequency increased during the study period. Antimicrobial-resistant bacteria gradually spread in healthy people in non-clinical settings; one reason behind this spread was dissemination of global antimicrobial-resistant pandemic clones.

Dissemination of IncF group F1:A2:B20 plasmid-harbouring multidrug-resistant Escherichia coli ST131 before the acquisition of blaCTX-M in Japan

OBJECTIVES

The Escherichia coli O25-ST131 clone is responsible for global dissemination of the bla_CTX-M gene. However, the prevalence of this clone in the digestive tract, devoid of antimicrobial selection, and its molecular epidemiology remain unclear. In this study, we examined the origin of bla_CTX-M-positive E. coli O25-ST131 and its distribution.

METHODS

We separately sequenced the chromosomal and plasmid genomes of 50 E. coli O25 isolates obtained from faecal samples of patients with diarrhoea in Japan.

RESULTS

Although 36 (72%) of 50 E. coli O25 isolates were ST131, only 6 harboured bla_CTX-M. According to the fimH and ybbW sequences and fluoroquinolone susceptibility, H30R1 isolates were dominant (27/36; 75%) and possessed IncFII-FIA-FIB with FAB formula subtype F1:A2:B20 plasmids at a high frequency (24/27; 89%). The F1:A2:B20 plasmids possessed more resistance genes such as bla_TEM-1, aminoglycoside resistance genes and trimethoprim/sulfamethoxazole resistance genes compared with non-F1:A2:B20 plasmids. In contrast, only one bla_CTX-M-14 gene was located on the F1:A2:B20 plasmids, whereas the other three were located on IncFII (F4:A-:B-) (n = 1) and IncZ (n = 2) plasmids. Two H30Rx-ST131 isolates harboured bla_CTX-M-15: one was on the chromosome and the other on the IncFIA-R plasmid. The stability and conjugation ability of the F1:A2:B20 plasmids were compared with those of non-F1:A2:B20 plasmids, which revealed higher stability but lower conjugative ability.

CONCLUSIONS

These results suggest that E. coli H30R1-ST131 is a multidrug-resistant clone containing several resistance genes in the F1:A2:B20 plasmid, which were widely distributed before the acquisition of bla_CTX-M.

Prevalence of 16S rRNA methylases in Gram-negative bacteria derived from companion animals and livestock in Japan

The emergence and spread of aminoglycoside-resistant bacteria are a public health concern. The acquisition of the genes encoding 16S rRNA methylases, such as armA, rmtA, and rmtB, confers high-level resistance to aminoglycosides. However, the prevalence has not been well investigated in Japanese veterinary fields. To determine the prevalence of 16S rRNA methylases in animals, we detected 16S rRNA methylases genes in Gram-negative bacteria from animals. Here, we report the isolation of rmtB and armA from two of the 446 Escherichia coli (0.5%) and one of the 103 Klebsiella spp. isolates (1.0%) from companion animals, respectively. However, none of the isolations were observed from 2445 E. coli isolates derived from livestock in Japan. The prevalence of 16S rRNA methylases in animals, especially in companion animals, should be carefully monitored in Japanese veterinary fields to avoid the spreading of the genes.

Prevalence and genetic characterization of cephalosporin-resistant Enterobacteriaceae among dogs and cats in an animal shelter

PURPOSE

The prevalence of antimicrobial-resistant bacteria, especially cephalosporin-resistant Enterobacteriaceae, is a major concern for human and animal health. We investigated the prevalence of cephalosporin-resistant Enterobacteriaceae among sheltered dogs and cats with various backgrounds.

METHOD

Faecal samples or rectal swabs were collected from 151 dogs and 182 cats, and screened for the presence of antimicrobial-resistant bacteria. Isolates were characterized phenotypically and genotypically by pulsed-field gel electrophoresis, multi-locus sequence typing and phylogenetic grouping. The animal attributes related to bacterial carriage were statistically analysed.

RESULTS

Cephalosporin-resistant Enterobacteriaceae was detected in 22 dogs (14.6%) and 20 cats (11.0%): 21 were extended-spectrum β-lactamase (ESBL)-producing, 20 were AmpC-producing, and 1 was both ESBL- and AmpC-producing. Their β-lactamase genes were varied and associated with humans, animals or other origins. The genes CTX-M-14 (n=9) and CMY-2 (n=9) were dominant, but CTX-M-1, CTX-M-2, CTX-M-8, CTX-M-15, CTX-M-24, CTX-M-27, CTX-M-55 and DHA-1 genes were also detected. Genotyping of isolates revealed that β-lactamase-producing Enterobacteriaceae had high genetic diversity. Relationships between animals harbouring cephalosporin-resistant Enterobacteriaceae and individual attributes, such as sex and nutrition type, were detected, but there was no correlation between history of human association and the presence of the bacterium in either dogs or cats.

CONCLUSION

We found several types of cephalosporin-resistant Enterobacteriaceae distributed among companion animals with a range of individual attributes and histories in Osaka, Japan. Companion animals may play a bridging role in the circulation of antimicrobial-resistant bacteria from humans and from other origins.

Prevalence of ESBL/AmpC genes and specific clones among the third-generation cephalosporin-resistant Enterobacteriaceae from canine and feline clinical specimens in Japan

In recent years, besides the widespread occurrence of extended-spectrum β-lactamase (ESBL)- and/or plasmid-mediated AmpC (pAmpC)-producing Enterobacteriaceae in both healthcare and community settings of humans, the third-generation cephalosporin (3GC)-resistant microbes have also been reported from companion animals worldwide. Here, we characterized ESBL- and/or pAmpC-producing Enterobacteriaceae clinical isolates from companion animals. Among the 487 clinical isolates mainly from urine of dogs and cats between May and September 2016, 104 non-repetitive isolates were resistant to the 3GC, and they consisted of 81 of 381 (21.3%) Escherichia coli, 21 of 50 (42.0%) Klebsiella pneumoniae, and 2 of 56 (3.6%) Proteus mirabilis isolates. In the 81 E. coli, the predominant bla genes were bla_CTX-M-27 and bla_CMY-2 (n = 15 each), followed by bla_CTX-M-15 (n = 14), bla_CTX-M-14 (n = 10), and bla_CTX-M-55 (n = 5). In 21 K. pneumoniae, 10 bla gene types including bla_CTX-M-15 (n = 4), bla_CTX-M-2 (n = 4), and bla_CTX-M-14 (n = 3) were found. The bla_CTX-M-2 was identified in 2 P. mirabilis. Twenty-four of the 42 E. coli belonging to phylogroup B2 were O25b-ST131 clone, mostly associated with uropathogenic E. coli pathotype, and 22 isolates of this clone were identified as specific H30R subclone. High prevalence of the bla_CTX-M-27-harboring isolates were noted among the H30R/non-Rx lineage (13/19, 68.4%) (p <  0.05). The genetic environment of bla_CTX-M-27 of most isolates of this lineage was identical to that of human isolates, but unique flanking genetic structures were also identified. Newly emerging virulent lineage B2-non-O25b-ST1193 was also confirmed in 5 isolates. The fosA3 and/or armA genes were detected in E. coli and K. pneumoniae isolates. These data suggest that companion animals serve as a potential reservoir of antimicrobial resistant E. coli and K. pneumoniae. This also has considerable veterinary importance, since urinary tract infections are an important disease causing therapeutic challenges worldwide.

Convergence of plasmid architectures drives emergence of multi-drug resistance in a clonally diverse Escherichia coli population from a veterinary clinical care setting

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Multi-drug resistant E. coli associated with urinary tract infections in dogs have a commensal strain background.

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Beta-lactam resistance is associated with bla_CMY-2 located exclusively on a highly clonal IncI1 plasmid.

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IncI1 plasmids carried no other identifiable resistance genes.

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Isolates in some cases carried up to 5 plasmids, responsible for carriage of the additional resistances.

The purpose of this study was to determine the plasmid architecture and context of resistance genes in multi-drug resistant (MDR) Escherichia coli strains isolated from urinary tract infections in dogs. Illumina and single-molecule real-time (SMRT) sequencing were applied to assemble the complete genomes of E. coli strains associated with clinical urinary tract infections, which were either phenotypically MDR or drug susceptible. This revealed that multiple distinct families of plasmids were associated with building an MDR phenotype. Plasmid-mediated AmpC (CMY-2) beta-lactamase resistance was associated with a clonal group of IncI1 plasmids that has remained stable in isolates collected up to a decade apart. Other plasmids, in particular those with an IncF replicon type, contained other resistance gene markers, so that the emergence of these MDR strains was driven by the accumulation of multiple plasmids, up to 5 replicons in specific cases. This study indicates that vulnerable patients, often with complex clinical histories provide a setting leading to the emergence of MDR E. coli strains in clonally distinct commensal backgrounds. While it is known that horizontally-transferred resistance supplements uropathogenic strains of E. coli such as ST131, our study demonstrates that the selection of an MDR phenotype in commensal E. coli strains can result in opportunistic infections in vulnerable patient populations. These strains provide a reservoir for the onward transfer of resistance alleles into more typically pathogenic strains and provide opportunities for the coalition of resistance and virulence determinants on plasmids as evidenced by the IncF replicons characterised in this study.

Selection of broad-spectrum cephalosporin-resistant Escherichia coli in the feces of healthy dogs after administration of first-generation cephalosporins

Although antimicrobial products are essential for treating diseases caused by bacteria, antimicrobial treatment selects for antimicrobial-resistant (AMR) bacteria. The aim of this study was to determine the effects of administration of first-generation cephalosporins on development of resistant Escherichia coli in dog feces. The proportions of cephalexin (LEX)-resistant E. coli in fecal samples of three healthy dogs treated i.v. with cefazolin before castration and then orally with LEX for 3 days post-operation (PO) were examined using DHL agar with or without LEX (50 µg/mL). LEX-resistant E. coli were found within 3 days PO, accounted for 100% of all identified E. coli 3-5 days PO in all dogs, and were predominantly found until 12 days PO. LEX-resistant E. coli isolates on DHL agar containing LEX were subjected to antimicrobial susceptibility testing, pulsed-field gel electrophoresis (PFGE) genotyping, β-lactamase typing and plasmid profiling. All isolates tested exhibited cefotaxime (CTX) resistance (CTX minimal inhibitory concentration ≥4 µg/mL). Seven PFGE profiles were classified into five groups and three β-lactamase combinations (bla_CMY-4 -bla_TEM-1 , bla_TEM-1 -bla_CTX-M-15 and bla_TEM-1 -bla_CTX-M-15 -bla_CMY-4 ). All isolates exhibited identical PFGE profiles in all dogs on four days PO and subsequently showed divergent PFGE profiles. Our results indicate there are two selection periods for AMR bacteria resulting from the use of antimicrobials. Thus, continuing hygiene practices are necessary to prevent AMR bacteria transfer via dog feces after antimicrobial administration.

Spread of CTX-Type Extended-Spectrum β-Lactamase-Producing Escherichia coli Isolates of Epidemic Clone B2-O25-ST131 Among Dogs and Cats in Japan

This study was performed to investigate the carriage rates of CTX-M-type extended-spectrum β-lactamase (ESBL)-producing Escherichia coli among ill companion animals in Japan. Among the 178 nonrepetitive E. coli isolates, including 131 from dogs and 47 from cats, collected between September and November 2015, 42 (23.6%) isolates from 29 dogs and 13 cats were identified as ESBL producers. The antimicrobial susceptibility, O serotype, phylogenetic group, β-lactamase genotype, plasmid replicon type, and sequence type (ST) of each isolate were analyzed. The major ESBL types were CTX-M-14 (26.8%), CTX-M-15 (24.4%), CTX-M-27 (19.5%), and CTX-M-55 (19.5%); predominant replicon types of bla_CTX-M-carrying plasmid were IncF group and IncI1-Iγ. The most prevalent STs were ST131 (n = 15, 35.7%), followed by ST38, ST10, and ST410. The 15 isolates of ST131 belonged to B2-O25. E. coli B2-O25-ST131 isolates harboring bla_CTX-M-15 or bla_CTX-M-27 were resistant to ceftazidime and ciprofloxacin. In particular, CTX-M-15 producers showed multidrug resistance. Our results demonstrated that the CTX-M-producing pandemic E. coli clone B2-O25-ST131 has already spread in Japanese companion animals as well. Moreover, the similarity of genotypes, serotypes, phylogenetic groups, and STs of the isolates from companion animals to those from humans suggested probable transmission of resistant bacteria between pets and humans.

Tigecycline Nonsusceptibility Occurs Exclusively in Fluoroquinolone-Resistant Escherichia coli Clinical Isolates, Including the Major Multidrug-Resistant Lineages O25b:H4-ST131-H30R and O1-ST648

Tigecycline (TGC) is a last-line drug for multidrug-resistant Enterobacteriaceae We investigated the mechanism(s) underlying TGC nonsusceptibility (TGC resistant/intermediate) in Escherichia coli clinical isolates. The MIC of TGC was determined for 277 fluoroquinolone-susceptible isolates (ciprofloxacin [CIP] MIC, <0.125 mg/liter) and 194 fluoroquinolone-resistant isolates (CIP MIC, >2 mg/liter). The MIC₅₀ and MIC₉₀ for TGC in fluoroquinolone-resistant isolates were 2-fold higher than those in fluoroquinolone-susceptible isolates (MIC₅₀, 0.5 mg/liter versus 0.25 mg/liter; MIC₉₀, 1 mg/liter versus 0.5 mg/liter, respectively). Two fluoroquinolone-resistant isolates (O25b:H4-ST131-H30R and O125:H37-ST48) were TGC resistant (MICs of 4 and 16 mg/liter, respectively), and four other isolates of O25b:H4-ST131-H30R and an isolate of O1-ST648 showed an intermediate interpretation (MIC, 2 mg/liter). No TGC-resistant/intermediate strains were found among the fluoroquinolone-susceptible isolates. The TGC-resistant/intermediate isolates expressed higher levels of acrA and acrB and had lower intracellular TGC concentrations than susceptible isolates, and they possessed mutations in acrR and/or marR The MICs of acrAB-deficient mutants were markedly lower (0.25 mg/liter) than those of the parental strain. After continuous stepwise exposure to CIP in vitro, six of eight TGC-susceptible isolates had reduced TGC susceptibility. Two of them acquired TGC resistance (TGC MIC, 4 mg/liter) and exhibited expression of acrA and acrB and mutations in acrR and/or marR In conclusion, a population of fluoroquinolone-resistant E. coli isolates, including major extraintestinal pathogenic lineages O25b:H4-ST131-H30R and O1-ST648, showed reduced susceptibility to TGC due to overexpression of the efflux pump AcrAB-TolC, leading to decreased intracellular concentrations of the antibiotics that may be associated with the development of fluoroquinolone resistance.

Extended spectrum β-lactamase and plasmid mediated quinolone resistance in Escherichia coli fecal isolates from healthy companion animals in Algeria

The aim of this study was to evaluate the rate of fecal carriage of Escherichia coli strains producing Extended-spectrum β-lactamases (ESBLs) and plasmid-mediated quinolone resistance (PMQR) isolated from healthy pets (dogs and cats) in Algeria. Fecal samples from 171 healthy pets (102 dogs and 69 cats) in one veterinary practice and private owners were included. After isolates identification, antibiotic susceptibility was determined by disk diffusion procedure. ESBL were detected by combination disk tests. PCR and sequencing were used to characterize genes encoding ESBLs and PMQR. Transfer of ESBL and PMQR genes was assessed by conjugation experiments. Phylogenetic groups of E. coli were determined by PCR. Of the 171 animals, 20 carried an ESBL producing E. coli giving a prevalence of ESBL fecal carriage of 11.7%. All isolates were susceptible to carbapenems, cefoxitin, piperacillin-tazobactam, amikacin and fosfomycine. For the rest of the tested β-lactams, susceptibility rates ranged from 35% to 70% for cefepime and amoxicillin-clavulanic acid respectively. Concerning the non-beta-lactams antibiotics, the rates of susceptibility ranged between 5% to trimethoprim and 95% for chloramphenicol. The beta-lactamase genes identified in E. coli isolates were blaCTX-M-15, blaCTX-M-1, blaSHV-12 and blaTEM-1. The PMQR determinants aac(6')-Ib-cr, qnrS1 and qnrB5 genes were identified in 15 isolates. Transconjugants were obtained for two isolates. Phylogenetic analysis showed that E. coli isolates belong to commensal phylogroups of A and B1. We reported here for the first time in Algeria ESBL and PMQR-producing E. coli in healthy cats and dogs.

CTX-M-1 and CTX-M-15-producing Escherichia coli in dog faeces from public gardens

Background

Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli are increasingly reported in dogs. The objective of this study was to provide data on the prevalence of ESBL-producing E. coli in dog faecal deposits in public gardens.

Results

A total of 209 faecal deposits collected in nine public gardens in Copenhagen, Denmark were screened by selective enrichment followed by plating on MacConkey agar supplemented with cefotaxime. Presumptive ESBL-producing E. coli were confirmed by MALDI-TOF MS and polymerase chain reaction (PCR) for detection of common cefotaxime resistance determinants (bla_TEM, bla_SHV, bla_CTX-M and bla_CMY-2). ESBL-producers were further characterized by multilocus sequence typing (MLST) and antimicrobial susceptibility testing using broth microdilution. Plasmids harbouring ESBL genes were characterized by S1 nuclease pulsed field gel electrophoresis, PCR-based replicon typing, and pMLST. Cefotaxime-resistant E. coli were detected in four (1.9 %) samples. Three samples harboured CTX-M-1-producing isolates, and one sample contained two CTX-M-15-producing isolates displaying distinct colony morphology. All isolates belonged to distinct sequence types (STs), including one E. coli lineage previously associated to a human-specific pathotype (ST59). bla_CTX-M-1 was carried on IncI1 plasmids classified as ST3 or ST58 by pMLST, whereas bla_CTX-M-15 was located on IncF/Y and non-typeable plasmids in the two strains isolated from the same sample.

Conclusions

The study shows that dog faeces are a vector for dissemination of CTX-M-producing E. coli within urban areas. The risk derived from human exposure to dog faeces in public gardens depends on the prevalence of these bacteria in the local dog population as well as on the owners’ practice to remove and dispose their dog’s faeces.

High prevalence of cross-resistance to aminoglycosides in fluoroquinolone-resistant Escherichia coli clinical isolates

BACKGROUND

Multidrug-resistant Escherichia coli, especially a lineage of O25b:H4-ST131, has increased and spread worldwide. The surveillance of cross-resistance of E. coli is necessary.

METHODS

Cross-resistance to fluoroquinolones (FQs) and aminoglycosides (AGs) was examined in E. coli isolated in Hokkaido Prefecture, Japan, between 2008 and 2009.

RESULTS

Gentamicin (GEN) resistance was more common in FQ-resistant isolates (30/112 strains; 26.8%) than in FQ-susceptible isolates (2/100 strains; 2%). The frequency of GEN resistance was similar in two groups of FQ-resistant strains, O25b:H4-ST131 genotype (22/87 strains; 25.3%) and a group of other FQ-resistant genotypes (8/25 strains; 32.0%). The main AG resistance gene was aac(3)-II (87.5% of GEN-resistant strains). The only amikacin-resistant strain which was FQ resistant carried the aac(6')-Ib-cr gene. CTX-M type extended-spectrum β-lactamase (ESBL) genes were also found in FQ-resistant strains at a high frequency. However, the number of strains with both ESBL and AG-modifying enzyme genes was relatively low (8 strains).

CONCLUSION

All FQ-resistant strains, not only O25b:H4-ST131, appeared to preferentially acquire ESBL genes and/or genes encoding AG-modifying enzymes; however, the acquisitions of these genes seemed to occur independently.