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PubMed2006

First description of CTX-M beta-lactamase-producing clinical Escherichia coli isolates from Egypt.

We studied the presence of beta-lactamases with an extended spectrum of activity in clinical Escherichia coli isolates from Cairo, Egypt. Forty-six E. coli isolates were collected from patients with urinary tract infections at a university hospital in 2001. Phenotypic characterisation identified a very high extended-spectrum beta-lactamase (ESBL) rate of 60.9%. Pulsed-field gel electrophoresis and plasmid profiles revealed eight different clonal groups. All ESBL producers were polymerase chain reaction-positive for blaTEM and blaCTX-M genes. Within the CTX-M family, three different enzymes, CTX-M-14, CTX-M-15 and CTX-M-27, were found. The ESBL producers carried multiple plasmids and further plasmid-encoded resistances. In several strains, genes for up to six aminoglycoside-modifying enzymes were detected. A linkage to fluoroquinolone resistance was not observed. This study confirms the high rate of ESBLs in Egypt and further demonstrates the worldwide spread of genes coding for CTX-M enzymes in clinical isolates.

Drug Resistance, Bacterial↗
PubMed2025

Influence of antimicrobial consumption (AMC) on the detection of antimicrobial resistance genes (ARGs) in urban wastewater.

BACKGROUND: Antimicrobial resistance (AMR) is a global health threat, causing over 1.27 million deaths annually and linked to an additional 4.95 million. AMR transmission occurs beyond clinical settings, with wastewater serving as a sentinel of community-level spread. This study investigated how temporal changes in antimicrobial consumption (AMC) correlate with the prevalence of antimicrobial resistance genes (ARGs) in wastewater, using wastewater surveillance (WS) to monitor resistance trends in Quebec, Canada. METHODOLOGY: AMC data (January 2019-May 2023) were obtained from the Institut National de Sant&#xe9; Publique du Qu&#xe9;bec (INSPQ) under a license from IQVIA Solutions Canada Inc. Wastewater samples (September 2020-September 2022) were obtained from three WWTPs and screened for 11 ARGs, including blaTEM, blaSHV, blaCTX-M, blaNDM, blaOXA-1/30, qnrA, qnrB, mphE, and mefA. Analyses assessed temporal and spatial associations between AMC and ARGs. RESULTS: Total prescriptions declined from 537 to 392 per 1000 inhabitants between 2019 and 2020 (-27&#xa0;%), likely due to the impact of the COVID-19 pandemic. This shift created a contrast that allowed us to better capture the signal of AMC through the noise in wastewater composition. &#x3b2;-lactams, macrolides, and fluoroquinolones were the most prescribed classes. ARGs were consistently detected in all 41 samples, with macrolide resistance genes being the most abundant. Strong correlations were observed between AMC and ARG prevalence in wastewater, particularly for &#x3b2;-lactams and fluoroquinolones (Spearman R&#xa0;=&#xa0;0.80 and 0.81, p&#xa0;<&#xa0;0.05). Spatial patterns showed uniform AMC but variable ARG levels. CONCLUSIONS: Our study highlights the correlation between AMC and ARG. WS shows promise for real-time AMR monitoring.

Wastewater↗
PubMed2026

From regionalization to homogenization: Nationwide metagenomic assessment of priority pathogens and the resistome in Polish hospital wastewater.

Hospital wastewater (HWW) is a critical hotspot for the dissemination of antibiotic resistance genes (ARGs) and pathogens. This study provides the first comprehensive metagenomic characterization of HWW across Poland, analyzing 64 medical facilities across two seasons via Nanopore long-read sequencing (total of 128 HWW samples). The HWW microbiome was mostly dominated by Proteobacteria, Bacteroidota, and Firmicutes. Multivariate analysis confirmed a significant seasonal shift in the resistome. Winter samples exhibited geographic regionalization, with localized hotspots of specific ARGs, including vancomycin resistance (operon van) and carbapenemase genes (blaOXA, blaNDM). Conversely, summer samples showed a significant trend toward nationwide homogenization, characterized by a uniform distribution of ESBL genes (blaTEM, blaCTX-M) and multidrug resistance (MDR) determinants, alongside the persistence of localized clinical hotspots. Klebsiella pneumoniae emerged as a central network hub, particularly in summer, showing strong correlations with ESBLs. Quantitative genomic co-occurrence analysis revealed a functional division within dominant taxa: while environmental species like Acinetobacter johnsonii comprised the general background microbiome, clinical pathogens such as Acinetobacter baumannii served as primary vectors, showing frequent associations with high-risk ARGs. Environmental and opportunistic bacteria, such as Aeromonas spp. and Citrobacter spp., were identified as putative 'bridge hosts' associated with mobile resistance determinants and potentially contributing to HGT. The findings indicate that seasonal factors, such as increased temperature and sub-inhibitory antibiotic concentrations, may contribute to the transition from regionalized to homogenized resistance profiles, demonstrating that background resistome convergence can coexist with point-source clinical outbreaks. This seasonal "blurring" of regional boundaries positions HWW as an active vector for large-scale antimicrobial resistance (AMR) dissemination. These results underscore the urgent need for nationwide metagenomic surveillance and advanced wastewater treatment strategies within the "One Health" framework to mitigate the environmental spread of WHO priority pathogens.

Acinetobacter baumannii↗
PubMed2006

Emergence of Escherichia coli isolates producing conjugative plasmid-mediated DHA-1 beta-lactamase in a Korean university hospital.

Seven isolates of cefoxitin-resistant Escherichia coli with an inducible phenotype were detected between November 2002 and July 2003 in a Korean hospital. Conjugations were tested by the filter mating method using azide-resistant E. coli J53 as the recipient. All isolates and their transconjugants were tested for broth microdilution minimum inhibitory concentrations, isoelectric focusing (IEF), polymerase chain reaction (PCR) for SHV, TEM, CTX-M and DHA-derived beta-lactamases, and DNA sequencing. XbaI-digested genomic DNA bands of the seven isolates were separated by pulsed-field gel electrophoresis (PFGE). IEF, PCR and sequence analysis revealed that all isolates possessed a blaTEM-1-like and a blaDHA-1 gene. Two isolates also carried the blaCTX-M-14 gene. Transfer of the resistance by conjugation experiments of all seven isolates was successful, suggesting that the blaDHA-1-containing plasmids in the E. coli isolates were self-transmissible. The isolates were recovered from patients in wards or an intensive care unit, all of which had been exposed to beta-lactams before isolation of the DHA-1 producers. Five patterns among the seven isolates were demonstrated by PFGE; sporadic infections with E. coli possessing an inducible beta-lactam resistance phenotype were found. DHA-1 encoded by conjugative plasmids conferred the resistance phenotype. The spread of the DHA-1 producers was due to both clonal spread and horizontal transfer of the resistance gene.

Adult↗
PubMed2006

Combinatorial genetic evolution of multiresistance.

The explosion in genetic information, whilst extending our knowledge, might not necessary increase our conceptual understanding on the complexities of bacterial genetics, or why some antibiotic resistant genotypes such as blaCTX-M-15 and blaVIM-2 appear to dominate. However, the information we have thus far suggests that clinical isolates have 'hijacked' plasmids, primarily built of backbone-DNA originating from environmental bacteria. Additionally, the combinatorial presence of other elements such as transposons, integrons, insertion sequence (IS) elements and the 'new' ISCR (IS common region) elements have also contributed to the increase in antibiotic resistance - an antibiotic resistant cluster composing four or five genes has become commonplace. In some instances, the presence of antibiotics themselves, such as fluoroquinolones, can mediate a bacterial SOS cell response, subsequently amplifying and/or augmenting the transfer of large genetic entities therefore, potentially promoting long-term detrimental effects.

Anti-Bacterial Agents↗
PubMed2026

Herd-level heterogeneity of antimicrobial resistance in commensal Escherichia coli: A nationwide high-throughput survey of Australian pig herds.

Antimicrobial resistance in commensal Escherichia coli provides a useful indicator for overall antimicrobial resistance burden. We applied this approach to assess antimicrobial resistance within and between commercial pig herds across Australia. A high-throughput robotic workflow was used to isolate 2730 E. coli colonies from rectal contents collected in 2022 from healthy slaughter pigs (n&#x202f;=&#x202f;300) representing 30 herds (&#x223c;70% of national production). Up to 94 isolates per herd underwent antimicrobial susceptibility testing using the Robotic Antimicrobial Susceptibility Platform. Isolate- and herd-level antimicrobial resistance indices were calculated, weighting antimicrobials by their human health importance. Resistance to first-line agents was widespread: ampicillin 77% and tetracycline 79%. By contrast, resistance to critically important antimicrobials was rare (ciprofloxacin 0.11%; extended-spectrum cephalosporins 0.04%), and no clinical resistance to carbapenems or colistin was detected. Overall, 56.9% of isolates were multi-class resistant. Herd-level antimicrobial resistance within indices ranged from 1.51 to 5.76, revealing substantial between-herd heterogeneity. Three herds carried critically important antimicrobials-resistant isolates that would likely have been missed using conventional, lower-density sampling approaches. Whole-genome sequencing identified fluoroquinolone-resistant isolates belonging to ST10 and ST69 (both qnrS1), and ST744 (Quinolone Resistance Determining Region mutations plus blaCTX-M-27). By testing approximately tenfold more isolates than conventional surveys, we uncovered considerable antimicrobial resistance with heterogeneity within and between animals and herds, including farm-specific variability. This expanded sampling also enabled detection of critically important antimicrobial resistance at very low prevalence. In conclusion, high-throughput, high-density testing offers a practical early-warning system and herd-level benchmark to inform surveillance and targeted interventions.

Animals↗
PubMed2026

Molecular characterization and antimicrobial resistance profiles of Shigella flexneri isolates from pediatric clinical cases in Ahvaz, Iran.

Shigella is a highly invasive pathogen that causes dysentery and is associated with significant morbidity and mortality in children under five years of age. This agent is a major public health problem in developing countries. Multiple-locus variable-number tandem repeat (VNTR) analysis (MLVA) is a reliable, cost-effective typing method with high discriminatory power and reproducible results. The rise of drug resistance in Shigella strains is a growing global health threat. Despite the significance of Shigella in Iran, there is limited knowledge about genetic diversity and drug resistance profiles of local strains. Therefore, the purpose of this study was to characterize the genetic diversity and drug resistance profiles of Shigella strains isolated in Ahvaz, Iran. A total of 49 Shigella flexneri isolates were recovered from 500 stool samples of pediatric patients. Routine biochemical tests were used to identify all isolates. Antimicrobial susceptibility testing was performed, and resistance genes were detected by polymerase chain reaction (PCR). Extended-spectrum &#x3b2;-lactamases (ESBL), carbapenemase, and Metallo-&#x3b2;-lactamase (MBL) production were detected phenotypically using combination disk assays and confirmed by the CLSI-recommended modified Carbapenem inactivation method (mCIM) and EDTA-modified carbapenem inactivation method (eCIM). MLVA based on seven VNTR loci was performed to characterize the genetic diversity of the isolates. All 49 isolates were resistant to ceftazidime, trimethoprim/sulfamethoxazole, ampicillin, and ceftriaxone (100% each). High resistance rates were also observed for imipenem 36/49 (73.5%), meropenem 36/49 (73.5%), azithromycin 21/49 (42.9%), and ciprofloxacin 16/49 (32.7%). Furthermore, phenotypic testing revealed ESBL production in 46/49 (93.9%) isolates and carbapenemase activity in 36/49 (73.5%), of which 22/49 (44.9%) were MBL. PCR analysis identified blaCTX-M 38/49 (77.6%) and blaSHV 35/49 (71.4%) as the most prevalent ESBL genes, whereas blaNDM 14/49 (28.6%), and blaOXA-48 14/49 (28.6%) were the most common carbapenemase genes. MLVA typing divided the isolates into 22 different MLVA types, including 10 clusters and 12 singletons, and locus ms21 showed the highest discriminatory power.&#xa0;The isolates exhibited high genetic diversity with a non-clonal distribution of resistance, which indicates dissemination through horizontal gene transfer. Our results demonstrated that mCIM/eCIM and MLVA are viable methods for investigating Shigella species as they are cost-effective, provide quick results, and allow for easy sharing of numerical data between laboratories.

Humans↗
PubMed2025

Molecular insights into carbapenemase-producing Enterobacterales from Senegal.

BACKGROUND: Carbapenemase-producing Enterobacterales (CPE) are an urgent global health threat, especially in resource-limited countries. Here we determined the prevalence and the molecular characteristics of CPE isolated from infections in Dakar, Senegal. METHOD: From January 2019 to December 2020, Enterobacterales with reduced susceptibility to ertapenem (diameter < 25&#x2005;mm) from infections were collected at the Pasteur Institute of Dakar. Carbapenemases were detected using biochemical and immunochromatographical assays. WGS was used to determine resistome, MLST, plasmids, virulence genes and genetic relatedness. RESULTS: Of the 1045 Enterobacterales collected during the study period, 86 had a diameter around ertapenem of <25&#x2005;mm (8%) and 19 were confirmed as CPE (2%). These included Escherichia coli (n&#x200a;=&#x200a;6) [ST410 (n&#x200a;=&#x200a;3), ST405 (n&#x200a;=&#x200a;2) and ST2083], Enterobacter spp. (n&#x200a;=&#x200a;6) [ST231 (n&#x200a;=&#x200a;3), ST245, ST760 and ST960] and Klebsiella spp. (n&#x200a;=&#x200a;5) (ST22, ST25, ST231, ST1535, ST4843), Citrobacter freundii ST22 (n&#x200a;=&#x200a;1) and Citrobacter koseri with unknown ST (n&#x200a;=&#x200a;1). blaOXA-48 (n&#x200a;=&#x200a;7; 35%), blaOXA-181 (n&#x200a;=&#x200a;7; 35%) and blaNDM-5 (n&#x200a;=&#x200a;6; 30%) genes were identified. C. freundii ST22 harboured blaNDM-5, blaOXA-48 and blaCTX-M-15 genes. Some E. coli isolates belonging to the high-risk clone ST410 were closely related (<20 SNPs) to isolates recovered in France from patients returning from Senegal, suggesting transnational spread. In addition, 5/6 carbapenemase-producing E. coli isolates possessed a four amino acid insertion in PBP3, conferring reduced susceptibility to aztreonam/avibactam and cefiderocol. CONCLUSIONS: This study highlights the spread of NDM-5 and OXA-181 in Senegal, and reports the first co-occurrence of NDM-5 and OXA-48 in sub-Saharan Africa. The spread of CPE, especially in high-risk clones, underscores the urgent need for continued surveillance and targeted interventions.

Senegal↗
PubMed2003

Effect of D240G substitution in a novel ESBL CTX-M-27.

Escherichia coli clinical strain Gre-1 collected in 2000 from a French hospital harboured a novel CTX-M-encoding gene, designated blaCTX-M-27. CTX-M-27 differed from CTX-M-14 only by the substitution D240G and was the third CTX-M enzyme harbouring this mutation after CTX-M-15 and CTX-M-16. The Gly-240-harbouring enzyme CTX-M-27 conferred to E. coli higher MICs of ceftazidime (MIC, 8 versus 1 mg/L) than did the Asp-240-harbouring CTX-M-14 enzyme. Comparison of CTX-M-14 and CTX-M-27 showed that residue Gly-240 decreased Km for ceftazidime (205 versus 940 microM), but decreased hydrolytic activity against good substrates, such as cefotaxime (kcat, 113 versus 415 s-1), probably owing to the alteration of beta3 strand positioning during the catalytic process.

Amino Acid Substitution↗
PubMed2003

Multiple antibiotic-resistance mechanisms including a novel combination of extended-spectrum beta-lactamases in a Klebsiella pneumoniae clinical strain isolated in Argentina.

Klebsiella pneumoniae M1803, isolated from a paediatric patient with chronic urinary infection, presented nine antimicrobial resistance mechanisms harboured on two conjugative megaplasmids, in addition to the chromosomally mediated SHV-1 beta-lactamase. These nine antimicrobial resistance mechanisms comprised two extended-spectrum beta-lactamases (ESBLs) (PER-2 and CTX-M-2), TEM-1-like, OXA-9-like, AAC(3)-IIa, AAC(6')-Ib, ANT(3")-Ia and resistance determinants to tetracycline and chloramphenicol. During fluoroquinolone treatment, a variant derived from M1803 (named M1826) was selected, with an overall increase of MICs, in particular of cefoxitin and carbapenems. No enzymic activity against these latter drugs was found. Mutations in the region analogous to the quinolone resistance-determining region were not found. Strain M1826 was deficient in OmpK35/36 expression, which produced the decrease in the susceptibility to cefoxitin, carbapenems and fluoroquinolones. The blaCTX-M-2 gene was located in an unusual class 1 integron, which includes Orf513, as occurred in the recently described In35. In addition, Tn3 and Tn1331 were detected in both K. pneumoniae isolates. This is the first report of in vivo selection of an OmpK35/36 deficiency in a K. pneumoniae strain that produced a novel combination of two ESBLs (CTX-M-2 and PER-2) during fluoroquinolone treatment in a paediatric patient with chronic urinary infection.

Argentina↗
PubMed2006

Occurrence of integrons and antimicrobial resistance genes among Salmonella enterica from Brazil.

OBJECTIVES: To determine the occurrence of antimicrobial resistance genes and role of integrons among 135 antimicrobial-resistant Salmonella enterica from Brazil. METHODS: The presence of antimicrobial resistance genes, class 1 and 2 integrons and gene cassettes was analysed by PCR and sequencing. The genetic location of class 1 integrons was determined in 25 isolates by hybridization and plasmid transfer experiments. RESULTS: Fifty-five of the isolates were positive for class 1 integrons. Integron-positive isolates represented 17 different serovars and were mainly from human (n=28) and animal (n=13) sources. The gene cassette arrangements could be determined in 51 of the positive isolates, which harboured one [dfrA22, aadA1 or orf3 (putative trimethoprim resistance)], two [aadA1-dfrA1, aac(6')-Ib-orf1 (unknown function) or aacA4-aadA1], three [dfrA15b-cmlA4-aadA2, orf2 (unknown function)-dfrA5-orfD] or four [orf4-aacA4-blaOXA-30 (interrupted by an IS1 element)-aadA1] cassettes in their variable region. Only one isolate harboured a class 2 integron with the gene cassette array dfrA1-sat-aadA1. Several integron unrelated resistance genes were also detected in the isolates. Sulphonamide resistance was primarily mediated by sul2 and sul3, tetracycline resistance by tet(B) and tet(A), chloramphenicol resistance by catA1, streptomycin resistance by strA and ampicillin resistance by blaTEM. blaCTX and blaCMY-2 were found in cephalosporin-resistant isolates. Mating and hybridization experiments demonstrated that a high-molecular-weight plasmid mediated the gene transfer of integrons and additional resistance determinants. CONCLUSIONS: The present study revealed that integron-mediated resistance genes contributed to the multiresistance phenotype observed in the isolates, but most resistance genes were located outside the integron structure, as independent genes. However, they might be located on the same conjugative plasmid.

Animals↗
PubMed2006

New antibiotic resistance genes associated with CTX-M plasmids from uropathogenic Nigerian Klebsiella pneumoniae.

OBJECTIVES: To determine antibiotic resistance genes associated with 17 Nigerian CTX-M-positive Klebsiella pneumoniae plasmids from patients with community-acquired urinary tract infections. METHODS: The size and restriction patterns of the plasmids were determined, and antibiotic resistance genes were identified using DNA-DNA hybridization, PCR assays, hybridization of PCR products with internal probes, and sequencing. RESULTS: All CTX-M plasmids were large (58-320 kb) and carried the following genes: aac(6')-Ib (aminoglycoside resistance) which included aac(6')-Ib-cr (aminoglycoside-fluoroquinolone resistance), aadA2 (aminoglycoside resistance), erm(B) (macrolide-lincosamide-streptogramin B resistance), blaTEM-1 (ampicillin resistance), tet(A) (tetracycline resistance), sul1 (sulphonamide resistance), dfr (trimethoprim resistance) and intI1, an integrase associated with class 1 integrons. Eleven (65%) plasmids carried an mph(A) gene (macrolide resistance), seven (41%) plasmids carried a qnrB1 gene (low-level quinolone resistance) and four (24%) plasmids carried multiple cat genes (chloramphenicol resistance). catA2, catA3 and qnrB1 genes and a 6 kb PstI fragment, carrying the blaCTX-M gene, were sequenced. CONCLUSIONS: This is the first description of catA2 and catA3 genes in Klebsiella spp. and the first description of the erm(B) and floR genes associated with a CTX-M plasmid. This is also the first report of qnrB1 and aac(6')-Ib-cr in isolates from Africa and the first report of these two genes on the same plasmid.

Base Sequence↗
PubMed2026

Global Diffusion of IncC Plasmid Harboring blaNDM-1in the High-Risk Escherichia coli ST131 Clone.

AIMS: The global expansion of quinolone-resistant Escherichia coli (QR-EC) is increasingly associated with &#x3b2;-lactam resistance and mobile genetic elements that facilitate resistance dissemination. This study investigated the molecular mechanisms underlying fluoroquinolone and &#x3b2;-lactam resistance in clinical QR-EC isolates and explored the plasmid type associated. METHODS AND RESULTS: A total of 123 non-duplicate QR-EC clinical isolates responsible mainly for gastrointestinal colonization were collected between 2019 and 2021. Plasmid-mediated quinolone resistance (PMQR), extended-spectrum &#x3b2;-lactamase (ESBL), and carbapenemase genes were screened by PCR. Mutations in the quinolone resistance-determining regions (QRDR) of gyrA and parC were analyzed using sequencing and mismatch amplification mutation assay PCR (MAMA-PCR). Selected isolates underwent multilocus sequence typing (MLST). Whole-genome sequencing (WGS) of a representative extensively drug-resistant strain carrying multiple quinolone resistance determinants, ESBL genes, and carbapenemase genes, was performed. PMQR genes were prevalent among QR-EC, dominated by aac(6')-Ib-cr (60.9% of isolates). ESBL genes were identified in 93.5% of isolates, predominantly blaCTX-M (95.7%). Among ertapenem-resistant isolates (QCR-EC) (n=18), blaNDM-1 and blaOXA-48 were detected in 13 and 11 isolates, respectively. QRDR mutations were highly frequent, particularly gyrA83 (98.4%) and parC80 (30.9%). Major QCR-EC genotypes belonged to sequence types ST167 (n=2), ST1196, ST469, and ST410. High-risk E. coli ST131 clone harboring IncC plasmid encoding blaNDM-1 was described for the first time in Africa, following its emergence, in two continents, Asia and America. Despite the very rare description of these strains worldwide, their description in three continents sign their global diffusion. CONCLUSIONS: This finding highlights the ongoing spread of carbapenem resistance and underscores the urgent need for strengthened genomic surveillance.

Escherichia coli↗
PubMed2005

Nosocomial spread of multi-resistant Klebsiella pneumoniae containing a plasmid encoding multiple beta-lactamases.

Six Klebsiella pneumoniae isolates that exhibited resistance to a wide spectrum of antibiotics were recovered from the intensive care units in the First Affiliated Hospital, Zhejiang University, Hangzhou, China. All isolates contained two plasmids of approximately 95 kb and 200 kb. The 95 kb plasmid was shown to be transferable by conjugation experiments. Isoelectric focusing patterns of the beta-lactamases extracted from the six transconjugants were identical, displaying five pI bands: 5.4, 7.75, 8.0, 8.2 and 8.4. The band corresponding to a pI of 7.75 could be inhibited by cloxacillin but not clavulanic acid, while the other bands could be inhibited by clavulanic acid but not cloxacillin. The 95 kb plasmid was digested with HindIII and a recombinant plasmid pT948 was obtained. The insert was found to contain blaDHA-1, regulatory gene ampR and an insertion element (IS26), which was downstream of blaDHA-1. PCR and DNA sequencing results confirmed that the 95 kb plasmid encoded at least four beta-lactamase genes: blaTEM-1, blaSHV-12), blaCTX-M-3 and blaDHA-1. Epidemiological typing by PFGE of the six clinical isolates of K. pneumoniae demonstrated identical genotypic patterns. In conclusion, all results indicated that the six multi-drug resistant clinical isolates of K. pneumoniae most probably originated from one clone and caused a localized epidemic in the intensive care units.

Anti-Bacterial Agents↗
PubMed2006

Clonal dissemination of a CTX-M-15 beta-lactamase-producing Escherichia coli strain in the Paris area, Tunis, and Bangui.

One hundred twenty CTX-M-15-producing Escherichia coli strains isolated in 10 different hospitals from Paris (France), in the Hospital Charles Nicolle in Tunis (Tunisia), and in the Pasteur Institute in Bangui, Central African Republic (CAR), between 2000 and 2004 were studied. Eighty isolates, recovered from the three countries, were clonally related by repetitive extragenic palindromic PCR and pulsed-field gel electrophoresis. Various resistance profiles were identified among these clonal strains. After conjugation or electroporation of plasmids from E. coli strains representative of each profile and each geographic region, we observed seven resistance profiles in the recipient strains. Incompatibility typing showed that all the plasmids transferred from the clonal strains studied, except one, belonged to the incompatibility group FII. They all shared a multidrug resistance region (MDR) resembling the MDR region located in pC15-1a, a plasmid associated with an outbreak of a CTX-M-15-producing E. coli strain in Canada. They also shared the common backbone of an apparent mosaic plasmid, including several features present in pC15-1a and in pRSB107, a plasmid isolated from a sewage treatment plant. This study suggests that although the plasmid-borne blaCTX-M-15 gene could be transferred horizontally, its dissemination between France, Tunisia, and CAR was due primarily to its residence in an E. coli clone with a strong propensity for dissemination.

Central African Republic↗
PubMed2006

Inhibitory impact of bifidobacteria on the transfer of beta-lactam resistance among Enterobacteriaceae in the gnotobiotic mouse digestive tract.

While looking for new means to limit the dissemination of antibiotic resistance, we evaluated the role of potentially probiotic bifidobacteria on the transfer of resistance genes between enterobacteria. Transfers of bla genes encoding extended-spectrum beta-lactamases (SHV-5 and CTX-M-15) were studied in the absence or presence of bifidobacteria. In vitro, transfer frequencies of these bla genes decreased significantly in the presence of three of five tested strains, i.e., Bifidobacterium longum CUETM-89-215, Bifidobacterium bifidum CIP-56.7T, and Bifidobacterium pseudocatenulatum CIP-104168T. Four transfer experiments were conducted in the digestive tract of gnotobiotic mice, the first three observing the effect of B. longum CUETM-89-215, B. bifidum CIP-56.7T, and B. pseudocatenulatum CIP-104168T on blaSHV-5 transfer and the fourth experiment studying the effect of B. bifidum CIP-56.7T on blaCTX-M-15 transfer. These experiments revealed significant decreases in the transconjugant levels (up to 3 logs) in mice having received B. bifidum CIP-56.7T or B. pseudocatenulatum CIP-104168T compared to control mice. Bifidobacteria appear to have an inhibitory impact on the transfer of antibiotic resistance genes. The inhibitory effect is associated to specific bifidobacterial strains and may be related to the production of thermostable metabolites by these strains.

Animals↗
PubMed2006

CTX-M beta-lactamase-producing Escherichia coli in French hospitals: prevalence, molecular epidemiology, and risk factors.

In 2004, 65 CTX-M-producing Escherichia coli isolates were collected from infected patients in four French hospitals. The blaCTX-M-15 genes were predominant. Pulsed-field gel electrophoresis highlighted a clonal propagation of CTX-M-15-producing strains belonging to phylogenetic group B2, notably in the community. The main risk factors for acquiring these isolates were urinary tract infections or the presence of a urinary catheter in diabetic or renal failure patients.

Aged↗