211 research outputs found
Plasmids Carrying blaCMY -2/4 in Escherichia coli from Poultry, Poultry Meat, and Humans Belong to a Novel IncK Subgroup Designated IncK2
No full textThe blaCMY -2/4-carrying IncB/O/K-like plasmids of seven Escherichia coli strains from poultry, poultry meat and human urine samples were examined using comparative analysis of whole plasmid sequences. The incompatibility group was determined by analysis of the incRNAI region and conjugation assays with strains containing the IncK and IncB/O reference plasmids. Strains were additionally characterized using MLST and MIC determination. The complete DNA sequences of all plasmids showed an average nucleotide identity of 91.3%. Plasmids were detected in E. coli sequence type (ST) 131, ST38, ST420, ST1431, ST1564 and belonged to a new plasmid variant (IncK2) within the IncK and IncB/O groups. Notably, one E. coli from poultry meat and one from human contained the same plasmid. The presence of a common recently recognized IncK2 plasmid in diverse E. coli from human urine isolates and poultry meat production suggests that the IncK2 plasmids originated from a common progenitor and have the capability to spread to genetically diverse E. coli in different reservoirs. This discovery is alarming and stresses the need of rapidly introducing strict hygiene measures throughout the food chain, limiting the spread of such plasmids in the human settings. © 2017 Seiffert, Carattoli, Schwendener, Collaud, Endimiani and Perreten
Resistance to polymyxins: genetic bases, epidemiology, and detection issues
No full textPolymyxins are old designed antibiotics that have recently regained significant interest as a consequence of the increasing prevalence of infections due to multidrug-resistant Gram-negative bacteria. In particular, colistin and polymyxin B are reconsidered as last-resort antibiotics in clinical medicine to treat infections due to extensively- or pan-drug-resistant Gram-negative bacteria producing carbapenemases. Unfortunately, polymyxin-resistant bacteria are also emerging in human, veterinary, food chain and environmental settings.
This talk presents recent works in relation to recently identified mechanisms of polymyxin resistance, including chromosomally encoded resistance traits as well as the recently identified plasmid-encoded polymyxin resistance determinant MCR-1, MCR-2 and MCR-3. Epidemiological features summarizing the current knowledge in the different settings and both genotypic and currently available phenotypic methods that provide relevant information for diagnostic laboratories will be also discussed
Resistance to carbapenems: mechanisms and detection methods
No full textIn the last two decades, carbapenems have been implemented for the treatment of infections due to last-generation cephalosporin-resistant Gram-negative infections. This massive use has contributed to the selection of carbapenem-resistant bugs that usually produce carbapenemase enzymes. Nowadays, the spread of such untreatable organisms has reached dramatic levels representing one of the most global public health problems. This issue has led to the realization of the need for more rapid diagnosis.
This talk presents a summary of the carbapenem resistance mechanisms. In particular, the main classes of carbapenemases will be discussed, emphasizing on their genetic background that support global spread. The currently available phenotypic and molecular methods that can be implemented by diagnostic and research laboratories will be also debated
Pseudomonas aeruginosa bloodstream infections: risk factors and treatment outcome related to expression of the PER-1 extended-spectrum beta-lactamase
No full textBackground: Bloodstream infection (BSI) due to Pseudomonas aeruginosa (Pa) has relevant clinical impact especially in relation to drug resistance determinants. The PER-I extended-spectrum beta-lactamase (ESBL) is a common enzyme conferring high-level resistance to anti-pseudomonal cephalosporins. Risk factors and treatment outcome of BSI episodes caused by PER-I-positive Pa (PER-I-Pa) strains were compared to those caused by ESBL-negative Pa isolates (ESBL-N-Pa). Methods: Twenty-six BSI cases due to ceftazidime-resistant Pa strains have been investigated. MIC values of anti-pseudomonal drugs were determined by the Etest method (AB Biodisk, Solna, Sweden). The double-disk synergy test was used to detect ESBL production. PCR amplification and DNA sequencing were used to characterize ESBL types. Clinical records of BSI-patients were examined retrospectively. Demographic data, underlying diseases (McCabe-Jackson classification and Charlson weighted index), risk factors, antimicrobial therapy, and treatment outcome were evaluated in cases due to ESBL-positive and cases due to ESBL-N-Pa isolates. Unpaired Student's t-test, Mann-Whitney U-test, Fisher's exact test and the χ2 test were used for statistical analysis. Results: Nine Pa isolates expressed the PER-I ESBL; the remaining 17 isolates did not produce ESBLs. Severe sepsis (P=0.03), bladder and intravascular catheters (both P=0.01), immunosuppressive therapy (P=0.04), and mechanical ventilation (P=0.03) were significantly associated with BSI due to PER-I-Pa. Empirical treatment (P= 0.02) and treatment after ID/AST (P<0.01) were rarely adequate in PER-I-Pa cases. With regard to treatment outcome, 77.8% BSI cases due to PER-I-Pa vs. 28.6% cases due to ESBL-N-Pa isolates failed to respond (P<0.03). All cases due to PER-I-Pa that were treated with carbapenems (alone or in combination with amikacin) failed to respond. In contrast, 7/8 cases due to ESBL-N-Pa given carbapenems were responders. Conclusion: Therapeutic failure and increased hospital costs are associated with BSI episodes caused by PER-I-Pa strains. Thus, recognition and prompt reporting of ESBL-production appears a critical factor for the management of patients with serious P. aeruginosa infections. © 2006 Endimiani et al; licensee Biomed Central Ltd
High colonization rates of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli
No full textBACKGROUND
International travel contributes to the worldwide spread of multidrug resistant Gram-negative bacteria. Rates of travel-related faecal colonization with extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae vary for different destinations. Especially travellers returning from the Indian subcontinent show high colonization rates. So far, nothing is known about region-specific risk factors for becoming colonized.
METHODS
An observational prospective multicentre cohort study investigated travellers to South Asia. Before and after travelling, rectal swabs were screened for third-generation cephalosporin- and carbapenem-resistant Enterobacteriaceae. Participants completed questionnaires to identify risk factors for becoming colonized. Covariates were assessed univariately, followed by a multivariate regression.
RESULTS
Hundred and seventy persons were enrolled, the largest data set on travellers to the Indian subcontinent so far. The acquired colonization rate with ESBL-producing Escherichia coli overall was 69.4% (95% CI 62.1-75.9%), being highest in travellers returning from India (86.8%; 95% CI 78.5-95.0%) and lowest in travellers returning from Sri Lanka (34.7%; 95% CI 22.9-48.7%). Associated risk factors were travel destination, length of stay, visiting friends and relatives, and eating ice cream and pastry.
CONCLUSIONS
High colonization rates with ESBL-producing Enterobacteriaceae were found in travellers returning from South Asia. Though risk factors were identified, a more common source, i.e. environmental, appears to better explain the high colonization rates
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