Prevalence and characterisation of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli isolates in healthy volunteers in Tunisia.

The objective of this investigation was to analyse the carriage rate of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli in faecal samples of healthy humans in Tunisia and to characterise the recovered isolates. One hundred and fifty samples were inoculated on MacConkey agar plates supplemented with cefotaxime (2 µg/ml) for ESBL-positive E. coli recovery. The characterisation of ESBL genes and their genetic environments, detection of associated resistance genes, multilocus sequence typing (MLST) and phylogroup typing were performed by polymerase chain reaction (PCR) and sequencing. The presence and characterisation of integrons and virulence factors were studied by PCR and sequencing. ESBL-positive E. coli isolates were detected in 11 of 150 faecal samples (7.3%) and one isolate/sample was further characterised. These isolates contained the blaCTX-M-1 (ten isolates) and blaTEM-52c genes (one isolate). The ISEcp1 (truncated by IS10 in four strains) and orf477 sequences were found upstream and downstream, respectively, of all bla (CTX-M-1) genes. Seven different sequence types (STs) and three phylogroups were identified among CTX-M-1-producing isolates [ST/phylogroup (number of isolates)]: ST58/B1 (3), ST57/D (2), ST165/A (1), ST155/B1 (1), ST10/A (1), ST398/A (1) and ST48/B1 (1). The TEM-52-producing isolate was typed as ST219 and phylogroup B2. Six ESBL isolates contained class 1 integrons with the gene cassettes dfrA17-aadA5 (five isolates) and dfrA1-aadA1 (one). Healthy humans in the studied country could be a reservoir of CTX-M-1-producing E. coli.

Detection of extended-spectrum beta-lactamase-producing Escherichia coli isolates in faecal samples of Iberian lynx.

AIMS: To characterize the diversity of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli isolates recovered within the faecal microbiota of Iberian lynx. The identification of other associated resistance genes and the analysis of clonal relationship were also focused in this study. METHODS AND RESULTS: From 2008 to 2010, 128 faecal samples of Iberian lynx (wild and captive animals) were collected. Eleven tested samples contained cefotaxime-resistant E. coli isolates (all belonging to captive animals) and 10 ESBL-producing isolates were showed. CTX-M-14 and SHV-12 ESBL-types were detected and seven different patterns were identified by pulsed-field gel electrophoresis analysis. CONCLUSIONS: The occurrence of unrelated multiresistant E. coli in faecal flora of captive specimens of Iberian lynx, including the presence of ESBLs, resistant genes in integrons and virulence determinants was showed in this study. SIGNIFICANCE AND IMPACT OF THE STUDY: The results obtained in this study highlight the environmental problem as future reintroductions of Iberian lynx could lead to a spread of resistant bacteria. Additionally, ESBL-producing bacteria can represent a health problem for this endangered species.