Multidrug-resistant Escherichia Coli Research Articles

Assessment of the presence of multidrug-resistant Escherichiacoli, Salmonella and Staphylococcus in chicken meat, eggs and faeces in Mymensingh division of Bangladesh

The emergence of bacteria that is resistant to several drugs of clinical importance poses a threat to successful treatment, a phenomenon known as multidrug resistance that affects diverse classes of antibiotics. The purpose of this study was to evaluate the prevalence of multidrug-resistant Escherichiacoli, Salmonella spp. and Staphylococcusaureus in chicken egg, meat and faeces from four districts of Bangladesh. A total of 120 chicken samples were collected from different poultry farms. Conventional culture and molecular detection methods were used for identification of bacterial isolates from the collected samples followed by antibiotic susceptibility test through the disc diffusion method, finally antibiotic resistant genes were detected by PCR. E. coli, Salmonella spp. and Staphylococcusaureus were detected in meat, egg and faecal samples. Antimicrobial susceptibility results revealed isolates from faeces were 100 % resistant to amoxicillin, while all S.aureus and Salmonella sp. from faeces were resistant to doxycycline, tetracycline and erythromycin. Salmonella spp. isolates from eggs indicated 100 % resistance to erythromycin, amoxycillin, while E.coli were 100 % resistant to erythromycin. E.coli and S.aureus from meat were 100 % resistant to amoxicillin and erythromycin. However, Salmonella spp. from eggs were 100 % susceptible to doxycycline, gentamicin, levofloxacin and tetracycline. The mecA and aac(3)-IV genes were only found in S.aureus and E.coli, respectively. The Sul1,tetB, and aadA1 were highest in Salmonella spp. and S.aureus, while the sul1,tetA and blaSHV were higher in E.coli. Isolates from all samples were multidrug resistant. These findings indicate a high risk of transmission of resistance genes from microbial contamination to food of animal origin. The study emphasizes the need for effective biosecurity measures, responsible antibiotic use, and strict regulations in poultry production to prevent the spread of antibiotic resistance.

Reversal of gentamicin sulfate resistance in avian pathogenic Escherichia coli by matrine combined with berberine hydrochloride.

In recent years, the evolution of antibiotic resistance has led to the inefficacy of several antibiotics, and the reverse of resistance was a novel method to solve this problem. We previously demonstrated that matrine (Mat) and berberine hydrochloride (Ber) had a synergistic effect against multidrug-resistant Escherichia coli (MDREC). This study aimed to demonstrate the effect of Mat combined with Ber in reversing the resistance of MDREC. The MDREC was sequenced passaged in the presence of Mat, Ber, and a combination of Mat and Ber, which did not affect its growth. The reverse rate was up to 39.67% after MDREC exposed to Mat + Ber for 15 days. The strain that reversed resistance was named drug resistance reversed E. coli (DRREC) and its resistance to ampicillin, streptomycin, gentamicin, and tetracycline was reversed. The MIC of Gentamicin Sulfate (GS) against DRREC decreased 128-fold to 0.63µg/mL, and it was stable within 20 generations. Furthermore, the susceptible phenotype of DRREC remained stable within 20 generations, as well. The LD50 of DRREC for chickens was 8.69 × 109 CFU/mL. qRT-PCR assays revealed that the transcript levels of antibiotic-resistant genes and virulence genes in the DRREC strain were significantly lower than that in the MDREC strain (P < 0.05). In addition, GS decreased the death, decreased the bacterial loading in organs, alleviated the injury of the spleen and liver, and decreased the cytokine levels in the chickens infected by the DRREC strain. In contrast, the therapeutic effect of GS in chickens infected with MDREC was not as evident. These findings suggest that the combination of Mat and Ber has potential for reversing resistance to MDREC.

A new in vivo model of intestinal colonization using Zophobas morio larvae: testing hyperepidemic ESBL- and carbapenemase-producing Escherichia coli clones.

Finding strategies for decolonizing gut carriers of multidrug-resistant Escherichia coli (MDR-Ec) is a public-health priority. In this context, novel approaches should be validated in preclinical in vivo gut colonization models before being translated to humans. However, the use of mice presents limitations. Here, we used for the first time Zophobas morio larvae to design a new model of intestinal colonization (28-days duration, T28). Three hyperepidemic MDR-Ec producing extended-spectrum β-lactamases (ESBLs) or carbapenemases were administered via contaminated food to larvae for the first 7 days (T7): Ec-4901.28 (ST131, CTX-M-15), Ec-042 (ST410, OXA-181) and Ec-050 (ST167, NDM-5). Growth curve analyses showed that larvae became rapidly colonized with all strains (T7, ~106-7 CFU/mL), but bacterial load remained high after the removal of contaminated food only in Ec-4901.28 and Ec-042 (T28, ~103-4 CFU/mL). Moreover, larvae receiving a force-feeding treatment with INTESTI bacteriophage cocktail (on T7 and T10 via gauge needle) were decolonized by Ec-4901.28 (INTESTI-susceptible); however, Ec-042 and Ec-050 (INTESTI-resistant) did not. Initial microbiota (before administering contaminated food) was very rich of bacterial genera (e.g., Lactococcus, Enterococcus, Spiroplasma), but patterns were heterogeneous (Shannon diversity index: range 1.1-2.7) and diverse to each other (Bray-Curtis dissimilarity index ≥30%). However, when larvae were challenged with the MDR-Ec with or without administering bacteriophages the microbiota showed a non-significant reduction of the diversity during the 28-day experiments. In conclusion, the Z. morio larvae model promises to be a feasible and high-throughput approach to study novel gut decolonization strategies for MDR-Ec reducing the number of subsequent confirmatory mammalian experiments.

Do we need to treat asymptomatic bacteriuria in immunocompromised patients? : Arapid review

Antimicrobial resistance (AMR), especially multidrug resistant Escherichiacoli strains, is aproblem even in Europe. That is why inadequate usage of antibiotic therapy should be avoided, especially in the treatment of asymptomatic bacteriuria (ASB). Should ASB be treated with antibiotics in immunocompromized patients, namely solid organ transplant, especially kidney transplant or stem cell transplant recipients? Arapid review based on asystematic literature search in MEDLINE between 1980 and 2022 was performed. For evidence synthesis, only randomized controlled trials (RCTs) or quasi-RCTs were considered. No studies were identified for the search term solid organ and stem cell transplantation. Three RCTs (antibiotic therapy versus no therapy) were included for adult kidney transplantation. None of the studies showed abenefit for antibiotic therapy of ASB in reduction of symptomatic urinary tract infections, especially in the late transplantation phase two months after kidney transplantation; furthermore, this therapy may promote AMR development. In addition, there are numerous gaps of evidence, e.g., in pediatric transplantation or regarding the influence of special immunosuppressants. There is no evidence for antibiotic therapy of ASB in adult kidney transplantation two months after the surgery. Further studies addressing the identified evidence gaps are essential for the prevention of further AMR development.

Pharmacodynamics of Piperacillin-Tazobactam/Amikacin Combination versus Meropenem against Extended-Spectrum β-Lactamase-Producing Escherichia coli in a Hollow Fiber Infection Model.

Carbapenems are recommended for the treatment of urosepsis caused by extended-spectrum β-lactamase (ESBL)-producing, multidrug-resistant Escherichia coli; however, due to selection of carbapenem resistance, there is an increasing interest in alternative treatment regimens including the use of β-lactam-aminoglycoside combinations. We compared the pharmacodynamic activity of piperacillin-tazobactam and amikacin as mono and combination therapy versus meropenem monotherapy against extended-spectrum β-lactamase (ESBL)-producing, piperacillin-tazobactam resistant E. coli using a dynamic hollow fiber infection model (HFIM) over 7 days. Broth-microdilution was performed to determine the MIC of E. coli isolates. Whole genome sequencing was conducted. Four E. coli isolates were tested in HFIM with an initial inoculum of ~107 CFU/mL. Dosing regimens tested were piperacillin-tazobactam 4.5 g, 6-hourly, plus amikacin 30 mg/kg, 24-hourly, as combination therapy, and piperacillin-tazobactam 4.5 g, 6-hourly, amikacin 30 mg/kg, 24-hourly, and meropenem 1 g, 8-hourly, each as monotherapy. We observed that piperacillin-tazobactam and amikacin monotherapy demonstrated initial rapid bacterial killing but then led to amplification of resistant subpopulations. The piperacillin-tazobactam/amikacin combination and meropenem experiments both attained a rapid bacterial killing (~4-5 log10) within 24 h and did not result in any emergence of resistant subpopulations. Genome sequencing demonstrated that all ESBL-producing E. coli clinical isolates carried multiple antibiotic resistance genes including blaCTX-M-15, blaOXA-1, blaEC, blaTEM-1, and aac(6')-Ib-cr. These results suggest that the combination of piperacillin-tazobactam/amikacin may have a potential role as a carbapenem-sparing regimen, which should be tested in future urosepsis clinical trials.

Genomic and Phenotypic Characterisation of Multi-Drug ResistantEscherichia coli carried by meat handlers and slaughterhouse meat from North-Western Tanzania

Our research is part of a larger project Supporting the National Action Plan on Antimicrobial Resistance (SNAP-AMR) in Tanzania. The aspect of this work is to determine the AMR carriage and associated mobile genetic elements of extended spectrum β-lactamase (ESBL) producing Escherichia coli within the community of Mwanza, in North-Western Tanzania. From 54 slaughterhouses a total of 322 E. coli isolates were obtained from raw meat, with 210 originating from meat handlers. Initial antimicrobial susceptibility testing identified 71 (22%) and 27 (13%) of the meat and meat handler isolates, respectively, as being ESBL E. coli. ST2852 was the most abundant MLST, followed by globally disseminated and ESBL associated ST38. Whole genome sequencing and phenotypic analysis revealed 88% of our isolates were resistant to three or more antimicrobial classes. On average, our isolates carried at least 10 different AMR associated genes, with 80% having one or more AMR conferring chromosomal mutation. In relation to ESBL, 88 out of 98 of the isolates carried the globally disseminated allotype blaCTX-M-15, with over 55% of the isolates encoding blaCTX-M-15on multi-drug resistant (MDR) plasmids. The remaining strains encoded one of three different blaCTX-Mallotypes. Our data highlights high prevalence of MDR ESBL E. coli within the community and its potential risk of transmission through the food chain. In our future work, we will combine these community carriage data with our work on ESBL Enterobacteriaceae carriage and infection within healthcare settings, to evaluate the genomic epidemiology of ESBL organisms in this region.

Short antimicrobial peptidomimetic SAMP-5 effective against multidrug-resistant gram-negative bacteria

SAMP-5 is a short histidine-derived antimicrobial peptidomimetic with pendant dialkylated tail. In this study, we evaluated the potential of SAMP-5 as an antimicrobial agent to combat multidrug-resistant gram-negative bacteria. SAMP-5 showed potent antimicrobial activity (minimum inhibitory concentration 16-64 μg/ml) comparable to melittin against multidrug-resistant Escherichia coli (MDREC) and multidrug-resistant (MDRPA). SAMP-5 displayed no cytotoxicity against three mammalian cells such as mouse macrophage RAW264.7, mouse embryonic fibroblast NIH-3T3, and human bone marrow SH-SY5Y cells at the concentration of 128 μg/ml. SAMP-5 showed resistance to proteolytic degradation with pepsin, trypsin, α-chymotrypsin, and proteinase K. Importantly, unlike ciprofloxacin, no antibiotic resistance against SAMP-5 arose for Pseudomonas aeruginosa during 7 days of serial passage at 0.5 × MIC. Moreover, SAMP-5 showed synergy or additive effects against MDRPA and MDREC, when it combined with chloramphenicol, ciprofloxacin, and oxacillin. Collectively, our results suggested that SAMP-5 is a promising alternative and adjuvant to treat infections caused by multidrug-resistant gram-negative bacteria.

Embelin-loaded chitosan gold nanoparticles interact synergistically with ciprofloxacin by inhibiting efflux pumps in multidrug-resistant Pseudomonas aeruginosa and Escherichia coli

A global upsurge in emergence and spread of antibiotic resistance (ABR) in bacterial populations is a serious threat for human health. Unfortunately, ABR is no longer confined to nosocomial environments and is frequently reported from community microbes as well. The ABR is resulting in shrinking potent antibiotics pool and thus necessitating novel and alternative therapies and therapeutics. Current investigation was aimed to assess the synergistic potential of a synthesized, phytomolecule-loaded, polysaccharide-stabilized metallic nanoparticles (NPs) against Pseudomonas aeruginosa (PA) and Escherichia coli (EC) isolated from river waters. ABR profiling of these strains characterized them as multidrug resistant (MDR). Synthesized embelin (Emb, isolated from Embelia tsjeriam-cottam)-loaded, chitosan-gold (Emb-Chi-Au) NPs were assessed for their potential synergistic activity with ciprofloxacin (CIP) via checker-board assay and time-kill curve analysis. The NPs reduced the minimal inhibitory concentration (MIC) of CIP by 16- and 4-fold against MDR PA (PA-r) and EC (EC-r) strains, respectively. Fractional inhibitory concentration (FIC) indices with ≤0.5 values confirmed the synergy between the Emb-Chi-Au NPs and CIP, which was further confirmed at ½ MICs in both PA-r and EC-r via time-kill curve analysis. In order to decipher the mode of action, efflux pump inhibitory effects of Emb-Chi-Au NPs were evaluated in terms of the increase in the EtBr mediated fluorescence in control versus NP-treated MDR strains. Molecular docking based in silico simulations were used to predict the interactions between Emb and the active sites of the efflux pump related proteins in PA-r (MexA, MexB and OprM) and EC-r (AcrA, AcrB and TolC), which revealed the probable bond formation between Emb and respective amino acid residues.

Genomic characterisation of a multidrug-resistant Escherichia coli strain carrying the mcr-1 gene recovered from a paediatric patient in China

ObjectivesThe global spread of carbapenem-resistant Enterobacterales is a leading public-health threat. Lack of effective treatment has resulted in use of colistin as a last-resort therapeutic option for multidrug-resistant (MDR) bacterial infections. Here we report the complete genome sequence of a MDR Escherichia coli strain carrying a plasmid-mediated colistin resistance gene mcr-1 recovered from a Chinese paediatric patient. MethodsWhole-genome sequencing of E. coli strain 1506 was performed using both Oxford Nanopore MinION and Illumina NovaSeq 6000 platforms. De novo hybrid assembly of short Illumina reads and long MinION reads was performed using Unicycler. In silico multilocus sequence typing (MLST), antimicrobial resistance genes (ARGs) and plasmid replicons were identified from the genome sequence. Core genome multilocus sequence typing (cgMLST) analysis between E. coli 1506 and all of the ST48 E. coli strains retrieved from the NCBI GenBank database was performed using BacWGSTdb 2.0 server. ResultsThe complete genome sequence of E. coli 1506 consists of six contigs comprising 4 849 058 bp, including one chromosome and five plasmids, and was assigned to ST48. Fourteen ARGs were identified, including mcr-1 located on a 33 309-bp IncX4 plasmid. The closest relative of E. coli 1506 was another isolate originating from livestock in Australia, which differed by 614 cgMLST alleles. ConclusionOur study reports the genome sequence of a MDR E. coli carrying mcr-1 isolated from a Chinese paediatric patient. These data may help to understand the antimicrobial resistance mechanisms and genomic features and highlight the growing threat of antimicrobial resistance in children.

High Prevalence of Multidrug-Resistant Escherichia coli in Urine Samples from Inpatients and Outpatients at a Tertiary Care Hospital in Sétif, Algeria.

The worldwide dissemination of multidrug-resistant (MDR) Enterobacteriaceae is a major public health issue. The aim of this study was to investigate the prevalence of MDR Escherichia coli (MDR-EC) isolates, in inpatients/outpatients with urinary tract infections at Sétif University Hospital (Algeria). Bacterial cultures were obtained from 426 of the 3,944 urine samples collected from January 2015 to February 2017. Among these cultures, 215 E. coli isolates were identified by mass spectrometry, and 38 (17.7%) were MDR-EC (disk diffusion method): 36 produced only extended-spectrum β-lactamases (ESBL), one ESBL and a carbapenemase, and one only a cephalosporinase (double-disk synergy test). Multiplex PCR and sequencing analyses showed that 37 ESBL-producing isolates harbored genes encoding CTX-M enzymes (CTX-M-15 in 33 isolates, 89.19%; and CTX-M-14 group in four isolates, 10.81%). One CTX-M-15-producing isolate co-expressed also an OXA-48-like carbapenemase. Phylogenetic group analysis of the 37 ESBL-producing and 178 non-ESBL-producing isolates indicated that the most common phylogenetic group was B2 (54.05% of ESBL-producing and 48.31% of non-ESBL-producing isolates), followed by A and D for ESBL-, and by B1, A, and F for non-ESBL-producing isolates. This is the first report highlighting the presence of MDR-EC isolates that produce both CTX-M and OXA-48-like enzymes in Sétif, Algeria.

Epidemiology of multidrug resistant bacterial organisms and Clostridium difficile in German hospitals in 2014: Results from a nationwide one-day point prevalence of 329 German hospitals.

BackgroundOne important aspect in combatting resistance to antibiotics is to increase the awareness and knowledge by epidemiological studies. We therefore conducted a German-wide point-prevalence survey for multidrug resistant bacterial organisms (MDROs) and Clostridium difficile (CD) to assess the epidemiology and structure quality of infection control in German hospitals.Method1550 hospitals were asked to participate and to report surveillance data on the prevalence of Methicillin-resistant and Vancomycin resistant Staphylococcus aureus (MRSA, VRSA/GRSA), Vancomycin resistant Enterococcus faecalis/faecium (VRE), multiresistant strains of Escherichia coli (EC), Klebsiella spp. (KS), Enterobacter spp. (ES), Acinetobacter spp. (AB) and Pseudomonas spp. (PS). as well as CD infections.ResultsSurveys from 73,983 patients from 329 hospitals were eligible for analysis. MRSA was the most often reported pathogen (prevalence: 1.64 % [CI95: 1.46-1.82]), followed by 3 multidrug resistant EC (3MRGN-EC) (0.75 % [CI95: 0.60–0.89]), CD (0.74 % [CI95: 0.60–0.88]), VRE (0.25 % [CI95: 0.13–0.37]) und 3MRGN-KS (0.22 % [CI95: [0.15–0.29]). The majority of hospitals met the German recommendations for staffing with infection control personnel.ConclusionThe continuing increase in participating hospitals in this third survey in a row indicates a growing awareness to MDROs and our pragmatic approach. Our results confirm that MRSA, 3MRGN-EC, VRE and 3MRGN-KS remain the most prevalent MDROs in German hospitals.

Evaluation of two multi-locus sequence typing schemes for commensal Escherichia coli from dairy cattle in Washington State

Multi-locus sequence typing (MLST) is a useful system for phylogenetic and epidemiological studies of multidrug-resistant Escherichiacoli. Most studies utilize a seven-locus MLST, but an alternate two-locus typing method (fumC and fimH; CH typing) has been proposed that may offer a similar degree of discrimination at lower cost. Herein, we compare CH typing to the standard seven-locus method for typing commensal E. coli isolates from dairy cattle. In addition, we evaluated alternative combinations of eight loci to identify combinations that maximize discrimination and congruence with standard seven-locus MLST among commensal E. coli while minimizing the cost. We also compared both methods when used for typing uropathogenic E. coli (UPEC). CH typing was less discriminatory for commensal E. coli than the standard seven-locus method (Simpson's Index of Diversity=0.933 [0.902–0.964] and 0.97 [0.96–0.979], respectively). Combining fimH with housekeeping gene loci improved discriminatory power for commensal E. coli from cattle but resulted in poor congruence with MLST. We found that a four-locus typing method including the housekeeping genes adk, purA, gyrB and recA could be used to minimize cost without sacrificing discriminatory power or congruence with Achtman seven-locus MLST when typing commensal E. coli.

Ionic liquid-supported chiral saldach with tunable hydrogen bonding: synthesis, metalation with Fe(III) and in vitro antimicrobial susceptibility

New water-soluble methylimidazolium ionic liquids (MIILs) bearing N,N′-bis-(salicylidene)-R,R-1,2-diaminocyclohexane (saldach) scaffold, H2(R1)2saldach(2-MeIm+X−)2 (4a: R1=H, X=Cl–; 4b: R1=H, X=PF6–; 4c: R1=H, X=BF4–; 4d: R1=iPr, X=Cl–; 4e: R1=iPr, X=PF6–; 4f: R1=iPr, X=BF4–), and their Fe(III) complexes have been synthesized and structurally characterized as well as their profile of antimicrobial susceptibility was identified. The new saldach-supported MIILs demonstrated a distinctly enhanced biocidal effect toward methicillin resistant Staphylococcus aureus (MRSA) and multidrug-resistant Escherichia coli (MDREC). Compound 4d is the most potent antibacterial agent and could inhibit the growth of all micro-organisms, except A. flavus, more effectively than standard antibiotics.

4‐Hydroxy‐α‐Tetralone and its Derivative as Drug Resistance Reversal Agents in Multi Drug Resistant Escherichia coli

The purpose of present investigation was to understand the drug resistance reversal mechanism of 4-hydroxy-α-tetralone (1) isolated from Ammannia spp. along with its semi-synthetic derivatives (1a-1e) using multidrug resistant Escherichia coli (MDREC). The test compounds did not show significant antibacterial activity of their own, but in combination, they reduced the minimum inhibitory concentration (MIC) of tetracycline (TET). In time kill assay, compound 1 and its derivative 1e in combination with TET reduced the cell viability in concentration dependent manner. Compounds 1 and 1e were also able to reduce the mutation prevention concentration of TET. Both compounds showed inhibition of ATP dependent efflux pumps. In real time polymerase chain reaction (RT-PCR) study, compounds 1 and 1e alone and in combination with TET showed significant down expression of efflux pump gene (yojI) encoding multidrug ATP binding cassettes (ABC) transporter protein. Molecular mechanism was also supported by the in silico docking studies, which revealed significant binding affinity of compounds 1 and 1e with YojI. This study confirms that compound 1 and its derivative 1e are ABC efflux pump inhibitors which may be the basis for development of antibacterial combinations for the management of MDR infections from inexpensive natural product.

Testing probiotic strain Escherichia coli Nissle 1917 (Mutaflor) for its ability to reduce carriage of multidrug-resistant E. coli by elderly residents in long-term care facilities

A high carriage rate of multidrug-resistant Escherichia coli (MDREC) was observed in elderly residents in long-term care facilities. A double-blinded, placebo-controlled trial was carried out to determine whether the probiotic product E. coli strain Nissle 1917 (Mutaflor) would compete with MDREC in the bowel and thereby reduce the prevalence of the multiresistant bacteria in faeces and urine. Sixty-nine patients excreting norfloxacin-resistant E. coli were randomized to probiotic or placebo groups and administered capsules twice daily. The daily dose of probiotic was 5×10(9)-5×10(10) bacteria. Faecal and urine samples were cultured at baseline and during and after the treatment period. A reduction in baseline carriage was not influenced by probiotic administration. The probiotic strain was detected in faecal specimens collected during the treatment period of only two out of 12 probiotic group subjects that were tested. Genotyping of norfloxacin-resistant E. coli isolates showed that 32 strains were prevalent among the patients. Thus, E. coli Nissle 1917 does not have the capacity to compete effectively with MDREC in the bowel of elderly patients.

Colonisation dynamics and virulence of two clonal groups of multidrug-resistant Escherichia coli isolated from dogs

The study established the virulence potential of multidrug-resistant Escherichia coli (MDREC) isolates from nosocomial infections in hospitalised dogs. The isolates were resistant to fluoroquinolones, belonged to two distinct clonal groups (CG1 and CG2) and contained a plasmid-mediated AmpC (CMY-7) β-lactamase. CG1 isolates ( n = 14) possessed two of 36 assayed extraintestinal virulence genes ( iutA and traT) and belonged to phylogenetic group A, whereas CG2 isolates ( n = 19) contained four such genes ( iutA, ibeA, fimH and kpsMT K5) and belonged to group D. In a mouse gastrointestinal tract colonisation model, colonisation by index CG1 strain C1 was transient, in contrast to the index CG2 strain C2b, which persisted up to 40 days post-inoculation. In a mouse subcutaneous challenge model, both strains were less virulent than archetypal group B2 extraintestinal pathogenic E. coli (ExPEC) strain CFT073; strain C1 caused no systemic signs and strain C2b was lethal to only one of six mice. In a mouse urinary tract infection model, strain C2b colonised the mouse bladder over 2 logs higher compared to strain C1. Whilst both groups of canine MDREC appear less virulent than a reference human ExPEC strain, CG2 strains have greater capacity for colonisation and virulence.

Emergence and spread of two distinct clonal groups of multidrug-resistant Escherichia coli in a veterinary teaching hospital in Australia

Multidrug-resistant Escherichia coli (MDREC) expressing AmpC beta-lactamases have emerged as a cause of opportunistic infections in dogs. Following a cluster of extraintestinal infections caused by two distinct clonal groups (CGs) of bla(CMY)-producing MDREC, a 12-month infection control study was undertaken at a veterinary teaching hospital in Brisbane, Australia. Swabs from the rectum of hospitalized dogs (n=780), hospital staff (n=16) and the hospital environment (n=220) were plated onto selective agar to obtain multidrug-resistant (MDR) coliforms. These were then tested by multiplex PCR for E. coli uspA, bla(CMY) and the class 1 integron-associated dfrA17-aadA5 gene cassette for rapid identification of MDREC CG 1 (positive for all three genes) and CG 2 (positive for uspA and bla(CMY) only). A total of 16.5 % of the dog rectal swabs and 4.1% of the hospital environmental swabs yielded MDREC, and on the basis of multiplex PCR, PFGE and plasmid profiling, these were confirmed to belong to either CG 1 or CG 2. Both CG 1 and CG 2 isolates were obtained from clinical cases of extraintestinal infection and rectal swabs from hospitalized dogs over the same period of time, whereas only CG 1 isolates were obtained from the hospital environment. Both CGs were prevalent during the first 6 months, but only CG 2 was isolated during the second 6 months of the study. Two isolates obtained from rectal swabs of staff working in the hospital belonged to CG 2, with one of the isolates possessing the same REDP as nine isolates from dogs, including six isolates associated with cases of extraintestinal infection. CG 1 isolates belonged to E. coli serotypes O162 : H-, OR : H- or Ont : H-, whereas CG 2 isolates belonged to O153 : HR, OR : HR or OR : H34. These results confirm that in this particular outbreak, canine MDREC were highly clonal and CG 2 MDREC may colonize both humans and dogs.

Identification of blaCMY-7 and associated plasmid-mediated resistance genes in multidrug-resistant Escherichia coli isolated from dogs at a veterinary teaching hospital in Australia

To determine clonality and identify plasmid-mediated resistance genes in 11 multidrug-resistant Escherichia coli (MDREC) isolates associated with opportunistic infections in hospitalized dogs in Australia. Phenotypic (MIC determinations, modified double-disc diffusion and isoelectric focusing) and genotypic methods (PFGE, plasmid analysis, PCR, sequencing, Southern hybridization, bacterial conjugation and transformation) were used to characterize, investigate the genetic relatedness of, and identify selected plasmid-mediated antimicrobial resistance genes, in the canine MDREC. Canine MDRECs were divided into two clonal groups (CG 1 and 2) with distinct restriction endonuclease digestion and plasmid profiles. All isolates possessed bla(CMY-7) on an approximately 93 kb plasmid. In CG 1 isolates, bla(TEM), catA1 and class 1 integron-associated dfrA17-aadA5 genes were located on an approximately 170 kb plasmid. In CG 2 isolates, a second approximately 93 kb plasmid contained bla(TEM) and unidentified class 1 integron genes, although a single CG 2 strain carried dfrA5. Antimicrobial susceptibility profiling of E. coli K12 transformed with CG 2 large plasmids confirmed that the bla(CMY-7)-carrying plasmid did not carry any other antimicrobial resistance genes, whereas the bla(TEM)/class 1 integron-carrying plasmid carried genes conferring resistance to tetracycline and streptomycin also. This is the first report on the detection of plasmid-mediated bla(CMY-7) in animal isolates in Australia. MDREC isolated from extraintestinal infections in dogs may be an important reservoir of plasmid-mediated resistance genes.