First Report of OXA-48 and IMP Genes Among Extended-Spectrum Beta-Lactamase-Producing Escherichia coli Isolates from Diarrheic Calves in Tunisia.

Antimicrobial resistance is one of the most serious threats to human and animal health. Evidence suggests that the overuse of antimicrobial agents in animal production has led to the emergence and dissemination of multidrug-resistant isolates. The objective of this study was to assess the rate of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli in calf feces and to characterize their resistance genes for antibiotics like beta-lactams and colistin, but also to determine their virulence genes. Fecal samples were collected from 100 diarrheic calves in the region of Bizerte, Tunisia. After isolation, E. coli isolates were screened for antimicrobial resistance against 21 antibiotics by the disc diffusion method. Characterization of ß-lactamase genes and determination of associated resistance genes were performed by polymerase chain reaction. Among 71 E. coli isolates, 26 (36.6%) strains were ESBL-producing. Most of these isolates were multidrug-resistant (92.3%) and the most prevalent beta-lactamase genes detected were blaCTX-M (n = 26), blaSHV (n = 11), and blaTEM (n = 8), whereas only 1 isolate carried the blaCMY gene. In addition, resistance to carbapenems was detected in two isolates; one of them harbored both blaOXA-48 and blaIMP genes and the other isolate carried only the blaIMP gene. Several resistance genes were identified for the first time in Tunisia from cases of diarrheic calves. Furthermore, to the best of our knowledge, this is the first report of detection and identification of carbapenem resistance genes and virulence genes from calves in North Africa. A high occurrence of antimicrobial resistance of E. coli recovered from fecal samples of calves with diarrhea was observed, highlighting the need for prudent use of antimicrobial agents in veterinary medicine to decrease the incidence of multidrug-resistant bacteria for both animals and humans.

Tunisian Multicenter Study on the Prevalence of Colistin Resistance in Clinical Isolates of Gram Negative Bacilli: Emergence of Escherichia coli Harbouring the mcr-1 Gene.

BACKGROUND: Actually, no data on the prevalence of plasmid colistin resistance in Tunisia are available among clinical bacteria. OBJECTIVES: This study aimed to investigate the current epidemiology of colistin resistance and the spread of the mcr gene in clinical Gram-negative bacteria (GNB) isolated from six Tunisian university hospitals. METHODS: A total of 836 GNB strains were inoculated on COL-R agar plates with selective screening agar for the isolation of GNB resistant to colistin. For the selected isolates, mcr genes, beta-lactamases associated-resistance genes and molecular characterisation were screened by PCRs and sequencing. RESULTS: Colistin-resistance was detected in 5.02% (42/836) of the isolates and colistin-resistant isolates harboured an ESBL (blaCTX-M-15) and/or a carbapenemase (blaOXA-48, blaVIM) encoding gene in 45.2% of the cases. The mcr-1 gene was detected in four E. coli isolates (0.59%) causing urinary tract infections and all these isolates also contained the blaTEM-1 gene. The blaCTX-M-15 gene was detected in three isolates that also carried the IncY and IncFIB replicons. The genetic environment surrounding the mcr-carrying plasmid indicated the presence of pap-2 gene upstream mcr-1 resistance marker with unusual missing of ISApl1 insertion sequence. THE CONCLUSIONS: This study reports the first description of the mcr-1 gene among clinical E. coli isolates in Tunisia and provides an incentive to conduct routine colistin susceptibility testing in GNB clinical isolates.

Extensively drug-resistant Acinetobacter baumannii co-producing VIM-2 and OXA-23 in intensive care units: Results of a one-day point prevalence in a Tunisian hospital.

OBJECTIVE: The main objective of this study was to identify carbapenem resistance mechanisms among clinical, commensal and environmental carbapenem-resistant Acinetobacter baumannii (CRAB) strains isolated in 5 Tunisian intensive care units (ICUs). MATERIALS AND METHODS: CRAB isolates were recovered from different sources: clinical specimens, rectal and environmental swabs. Bacterial identification was carried out using conventional methods and susceptibility testing according to EUCAST recommendations. Evaluation of phenotypic carbapenemase production of was performed using seven different methods, and molecular detection of carbapenemase-coding genes (blaOXA23, blaOXA24, blaOXA58, blaNDM, blaGES, blaOXA48, blaIMP, blaVIM and blaKPC) was done by PCR. The genetic relationships between CRAB isolates were analyzed by pulsed-field gel electrophoresis. RESULTS: All in all, 46 CRAB isolates were identified in clinical specimens (n = 26/26), rectal swabs (n = 17/36) and environmental swabs (n = 3/63). Most of them (n = 41/46) were clonally related and found in the different ICUs. All of the CARB isolates harbored blaOXA-51-like and blaOXA-23 genes, while blaVIM-2 gene was detected in 42 isolates (91.3 %). Phenotypic carbapenemase activity was found in all 46 strains, using the CIM-Tris test with 100 % sensitivity for OXA-23 and VIM-carbapenemase detection, thereby justifying its routine use. CONCLUSION: The emergence and diffusion of clonal CRAB strains inducing high mortality rates in ICUs is a major public health concern. Enhanced infection control practices and mandatory staff education are needed to control the spread of these multidrug-resistant bacteria.

Evaluation of Three Carbapenemase-Phenotypic Detection Methods and Emergence of Diverse VIM and GES Variants among Pseudomonas aeruginosa Isolates in Tunisia.

BACKGROUND: Since 2012, few reports on the molecular epidemiology of Pseudomonas aeruginosa were reported in Tunisia. OBJECTIVES: This study aimed to evaluate carbapenem-resistance determinants and molecular epidemiology and to compare the carbapenemase-phenotypic detection methods of multidrug-resistant P. aeruginosa isolates. METHODS: During a period of four years (2014 to 2017), all imipenem-ceftazidime-resistant P. aeruginosa isolates were retrospectively selected at the microbial laboratory of Charles Nicolle hospital of Tunis. These isolates were examined by the modified Hodge test, modified carbapenem inactivation method (mCIM), and another mCIM, called CIMTris, and their performance was evaluated using PCR analysis as the gold standard. RESULTS: A total of 35 isolates were recovered among patients hospitalized in different units. All strains were colistin-susceptible.All carbapenem-resistant isolates showed a high-level resistance to carbapenems. CIMTris and mCIM showed 96.15% and 46.15% sensitivity and 44.44% and 100% specificity, respectively, for detecting carbapenemase production. CONCLUSIONS: CIMTris is a promising approach for detecting carbapenemase activity in P. aeruginosa and merits further testing. Moreover, this study described the first detection of GES-5- and GES-9-producing P. aeruginosa in Tunisia as well as the co-occurrence of the blaGES-5 and blaVIM-11 carbapenemase genes in one isolate. These findings are of great concern because the rapid dissemination of MDR strains represents a major therapeutic and epidemiological threat.

Prognostic Value of High-sensitivity Troponin I in Patients with Septic Shock: A Prospective Observational Study.

BACKGROUND: Myocardial dysfunction is one of the mechanisms involved in the pathophysiology of septic shock. The role of troponin as a surrogate of myocardial injury in septic shock is still debated. The aim of this study was to assess the prognostic value of high-sensitivity cardiac troponin I (hs-cTnI) assay in predicting 28-day mortality in patients with septic shock. MATERIALS AND METHODS: Prospective study including 75 patients with septic shock admitted to a medico-surgical ICU from January to December 2017. Patients under the age of 18 years, known pregnancy and patients in post-cardiac arrest were excluded. Clinical and demographic data including age, gender, comorbidities, SAPS II and SOFA scores were collected. Hs-cTnI was measured soon after admission and 12, 24, 48 and 72 after. Receiver operating characteristic (ROC) analysis was performed to identify the most useful troponin I cut-off level for the prediction of 28-day mortality. A p <0.05 was considered significant. RESULTS: Seventy-five (M/F = 53/22) patients with septic shock were included in the study. The median SOFA and SAPS II scores were 10 and 42, respectively. The median duration of mechanical ventilation was 8 days and the median length of ICU stay was 11 days. The 28-day mortality was 54.6%. We found a high prevalence (47%) of elevated hs-cTnI in patients with septic shock. Median hs-cTnI on admission in the whole group was 36 ng/L. The 28-day mortality was found to be related to age (p <0.001), SAPS II score (p = 0.001), mean arterial pressure (p = 0.038), lactate (p <0.001) and glomerular filtration rate (p <0.001).Hs-cTnI levels were significantly higher in non-survival group than survival one at all time points: H12 (p = 0.006), H24 (p = 0.003), H48 (p = 0.005) and H72 (p=0.001). In multivariate analysis, hs-cTnI at H72 was independently associated with 28-day mortality. CONCLUSION: Hs-cTnI elevation at 72 hours was associated with 28-day mortality in septic shock patients. HOW TO CITE THIS ARTICLE: Jendoubi A, Jerbi S, Maamar E, Abbess A, Samoud Z, Kanzari L, et al. Prognostic Value of High-Sensitivity Troponin I in Patients with Septic Shock: A Prospective Observational Study. Indian J Crit Care Med 2019;23(7):320-325.

Escherichia coli colonizing healthy children in Tunisia: High prevalence of extra-intestinal pathovar and occurrence of non-extended-spectrum-ß-lactamase-producing ST131 clone.

This study was performed to investigate the distribution of antimicrobial resistance genes and extra-intestinal virulence determinants in a collection of 98 Escherichia coli strains isolated from rectal swabs of healthy children. Forty-six isolated strains were resistant to at least one of the tested antibiotics (usually active against enterobacteria). They were mainly resistant to ampicillin and ticarcillin (42.97%), tetracyclin (26.5%), and trimethoprim/sulfamethoxazole (18.4%). No resistance to the third generation of cephalosporins, carbapenems, aminoglycosides and colistin was found. Resistance to penicillins was encoded by blaTEM-1 (n=34) and blaSHV-1 genes (n=4). Tetracyclin resistance was encoded by tetB (n=12), tetA (n= 5), and tetC (n=1) genes. Amongst resistant quinolones isolated (n=5), chromosomal mutations in gyrA and parC genes were detected in four isolates and qnrS1 gene in two strains. Nine plasmid replicon types were detected; IncFIB (n=36) and IncI1 (n=7) were the most frequent ones. Isolates frequently belonged to phylogenetic groups A (51.1%) and D (27.5%). Extra-intestinal pathovar (n=38) occurred mainly in B2 phylogroup (P=0.0002). Amongst them, two isolates (non-extended-spectrum-ß-lactamase (ESBL)-producers) belonged to the pandemic clone ST131. A significant distribution of virulence determinants and pathogenicity island marker was observed within strains belonging to B2 and D phylogroups. Interestingly, our results showed that ExPEC strains, including ST131 pandemic clone, are present within fecal isolates in healthy children. These findings highlight the importance of intestinal microbiota as a reservoir for virulent and resistant strains. Thus, reinforcing hand hygiene and antibiotic rational use is imperative to avoid the diffusion of these pathogens in the community.

Role of association of OmpK35 and OmpK36 alteration and blaESBL and/or blaAmpC genes in conferring carbapenem resistance among non-carbapenemase-producing Klebsiella pneumoniae.

In Klebsiella pneumoniae, loss of the two major outer membrane porins (OMPs) OmpK35 and OmpK36 confers resistance to carbapenems in strains producing extended-spectrum ß-lactamases (ESBLs) or plasmid-mediated AmpC-type ß-lactamases. This study investigated mechanisms responsible for carbapenem resistance in non-carbapenemase-producing K. pneumoniae (NCPK). All carbapenem-resistant Enterobacteriaceae (CRE) at Charles Nicolle Hospital (Tunis, Tunisia) were collected over a 6-year period (2010-2015). Among the 334 CRE strains collected, 44 (13.2%) were NCPK. MIC ranges for ertapenem, imipenem and meropenem were 1 to >32 mg/L, 0.125-8 mg/L and 0.125-32 mg/L, respectively. All strains showed a multidrug-resistant (MDR) phenotype and were negative for carbapenemase activity. None of the carbapenemase genes searched for were found. ESBL production was confirmed in all isolates except one [CTX-M-15 (n = 39) and SHV-5 (n = 4)]. Three isolates produce DHA-1 (associated with CTX-M-15 in two strains). Molecular fingerprints grouped the 44 NCPK isolates into seven clusters. In seven representative strains of these clusters, SDS-PAGE results showed that four isolates lacked the OmpK35 porin, one isolate lacked OmpK36 and two isolates lacked both OmpK35 and OmpK36. Sequencing of the corresponding porin genes showed amino acid insertions and deletions leading to early termination of translation, point mutations in the promoter region, or insertion sequences disrupting the gene coding sequence. Loss or deficiency of OMPs, coupled with ESBL and/or AmpC production, plays an important role in conferring carbapenem resistance in K. pneumoniae. Dissemination of these MDR bacteria in our hospital may create serious therapeutic problems in the future.

NDM-1- and OXA-23-producing Acinetobacter baumannii isolated from intensive care unit patients in Tunisia.

Gastrointestinal colonisation by carbapenem-resistant Acinetobacter baumannii (CRAB) is a critical step before nosocomial infection. This study evaluated CRAB intestinal carriage in patients admitted to a Tunisian ICU and determined the antimicrobial resistance mechanisms involved. From December 2014 to February 2015, all 63 patients admitted to the ICU were screened for rectal CRAB colonisation upon admission and once weekly thereafter. ICU patients who acquired a CRAB nosocomial infection were also included. ß-Lactamases and associated resistance genes were screened by PCR sequencing, and molecular typing was performed by PFGE and MLST. The CRAB faecal carriage rate at admission was 4.8% (3/63). The CRAB acquisition rate during ICU stay was analysed in 39 of the remaining 60 patients and the rate of acquired CRAB faecal carriage was 15.4% (6/39); 4 patients also showed an ICU-acquired CRAB infection (one patient was a faecal carrier and suffered infection). Overall, 13 CRAB isolates were collected from 12 patients, of which 11 isolates showed resistance to all antibiotics tested except colistin. blaOXA-23 and blaNDM-1 were detected in 11 and 2 isolates, respectively. All OXA-23-producing strains carried armA, tetB, sul1 and catB, and some of them carried aph(3')-VIa, blaTEM-1, aph(3')-Ia and ant(2'')-Ia. The blaNDM-1-positive isolates harboured aph(3')-VIa and catB. Three PFGE patterns and two STs were identified [ST195 (n = 11), ST1089 (n = 2, NDM-1-positive)]. Whether imported or acquired during ICU stay, CRAB colonisation is a major risk factor for the occurrence of serious nosocomial infection. Systematic screening of faecal carriage is mandatory to prevent their spread.

Molecular diversity and conjugal transferability of class 2 integrons among Escherichia coli isolates from food, animal and human sources.

Integrons are genetic platforms able to excise, integrate and express antibiotic resistance gene cassettes (GCs). Here we investigated the complete genetic organisation, genetic environment, location and conjugative transferability of a collection of class 2 integrons carried by Escherichia coli strains from different sources (poultry/pork meat, animals and humans). PCR cartography was conducted to determine the genetic arrangement of the integrons, their physical linkage to Tn7 and chromosomal insertion at the attTn7 site. Clonal relatedness of specific isolates was determined by MLST and DO-PCR. Transferability of class 2 integrons was tested by conjugation. The resulting transconjugants were characterised by antimicrobial resistance genotyping, S1-PFGE and replicon typing. Although a limited diversity of GCs was shown, a high percentage of novel structures was identified owing to the integration of insertion sequence (IS) elements at different sites (IS3/IS4/IS5/IS21 families). Insertion of IS10 in the attI2 site of a class 2 integron, between Pc2B and Pc2C promoters, was likely mediated by a site-specific transposition event. Chromosomal insertion of integrons at attTn7 was confirmed in 80% of the isolates. Conjugation experiments demonstrated that 29% of class 2 integrons could be mobilised to E. coli CHS26, demonstrating that they can be located in conjugative/mobilisable elements at a low frequency. Reported structures evidence how class 2 integrons have evolved by the activity of integron integrases and the invasion of ISs. Since most of them are chromosomally located, dispersion is predominantly vertical, although conjugation events also contribute to the spread of class 2 integrons among bacterial communities.

Emergence of plasmid-mediated colistin-resistance in CMY-2-producing Escherichia coli of lineage ST2197 in a Tunisian poultry farm.

Our study aimed to investigate colistin resistance and the mechanisms involved in a collection of 35 extended-spectrum beta-lactamase (ESBL) and 13 CMY-2-producing E. coli strains which were previously recovered from chicken gut microbiota in Tunisia, as well as to determine the genetic location of mcr genes. Forty-eight ESBL and CMY-2-producing E. coli strains were obtained from 137 fecal samples of healthy chickens during 2013. These strains were tested for colistin resistance by the broth microdilution method, and screened for mcr-1 and mcr-2 genes by PCR. Two of these strains were colistin-resistant (MIC = 8 mg/L). Both harbored the mcr-1 gene, were CMY-2 producers, and were additionally resistant to tetracycline, ciprofloxacin, chloramphenicol, gentamicin, tobramycin and trimethoprim-sulfamethoxazole. They shared phylogroup A, the same pulsed-field gel electrophoresis (PFGE)-pattern, and were typed as ST2197. In both strains, ISApl1 and pap2 were detected upstream and downstream of mcr-1 gene, respectively. The analysis of the two mcr-1-positive strains and their transconjugants by PCR-based replicon typing and S1-PFGE, demonstrated that mcr-1 gene is linked to an IncP plasmid (~242 kb), and blaCMY-2 to an IncI1 plasmid (97 kb). The occurrence of E. coli harboring mcr-1 gene among intestinal microbiota in poultry and its location on a conjugative plasmid could represent a risk for public health. The evolution of this type of resistant microorganisms should be evaluated in the future.

An Outbreak of NDM-1-Producing Klebsiella pneumoniae, Associated with OmpK35 and OmpK36 Porin Loss in Tunisia.

OBJECTIVES: To describe clinical and molecular characteristics of an outbreak due to metallo-ß-lactamases (MBLs) producing Klebsiella pneumoniae collected at Charles Nicolle Hospital of Tunis and to analyze the impact of outer membrane porin (OMP) loss on carbapenem resistance levels. METHODS: Between 2010 and 2015, 178 carbapenem-resistant Enterobacteriaceae were isolated. Screening for MBL production was performed using combined disk diffusion method, with imipenem and ethylene diamine tetraacetic acid (EDTA) as inhibitors. Resistance genes and virulence factors were identified by polymerase chain reaction (PCR) and sequencing. Genotyping was performed by pulsed-field gel electrophoresis and multilocus sequence typing. Genetic environment of carbapenemase genes was determined by PCR mapping. Conjugation assays were performed, and plasmids were assigned to incompatibility groups by PCR-based replicon typing. OMPs were profiled by sodium dodecyl sulfate-polyacrilamide gel electrophoresis, and porin genes were sequenced. RESULTS: Nineteen K. pneumoniae (10.6%) showing MBL activity were isolated from patients hospitalized on four different wards. NDM-1 was the only MBL identified, in association with blaOXA-48. All strains lacked at least one OMP, and carbapenem resistance levels were remarkably elevated in strains lacking OmpK35 and OmpK36. blaNDM-1 was located in IncFIA-type conjugative plasmid, with the same genetic context in all strains. The epidemiological diffusion of blaNDM-1 was due to two clones, one major clone belonging to sequence type (ST) 147 (n = 16) and the other clone belonging to ST307 (n = 3). CONCLUSIONS: This study describes an outbreak of NDM-1-producing K. pneumoniae strains, isolated from a Tunisian hospital, caused by two clones belonging to ST147 and ST307; and highlights the role of OMPs loss, in combination with ß-lactamase expression, in conferring high carbapenem resistance.

Rectal Carriage of Extended-Spectrum Beta-Lactamase and Carbapenemase Producing Gram-Negative Bacilli in Intensive Care Units in Tunisia.

This study was conducted to evaluate the rate of fecal carriage of Gram-negative bacilli (GNB) resistant to third-generation cephalosporins (third GC) in patients hospitalized in the intensive care unit (ICU) of Charles Nicolle Hospital of Tunis and to identify the enzymatic mechanisms involved. From February to April 2014, rectal swabs were collected from all patients (n = 38) at admission and once weekly thereafter to identify acquisition. They were cultured on desoxycholate-lactose-agar plates supplemented with cefotaxime (2 mg/L). The rate of fecal carriage of GNB resistant to third GC was 0% (0/38) at admission and the acquisition rate was 45.16% (14/31). Nineteen GNB resistant to C3G were collected from 14 patients. The major species collected were Acinetobacter baumannii (n = 5), Klebsiella pneumoniae (n = 5), and Enterobacter cloacae (n = 5). Thirteen extended-spectrum ß-lactamase (ESBL) producing GNB were found; CTX-M-15 (n = 10) and CTX-M-14 (n = 1) among Enterobacteriacae and GES-12 (n = 2) among A. baumannii. Ten strains were carbapenem resistant. OXA-48 (n = 4) and NDM-1 (n = 1) were detected among Enterobacteriacae and OXA-23 (n = 5), and GES-11 (n = 1) were detected in A. baumannii. Gene encoding the ACT-16 AmpC-type-ß-lactamase was detected in two isolates. All Escherichia coli isolates were assigned to group B2. Among virulence genes, prevalence of fimH, fuyA, ompT, pai, and usp were highest observed in all E. coli isolates. Among K. pneumoniae mrkD and entB were the most frequent (n = 5) followed by ybtS (n = 4) and kfu (n = 2). This study revealed a high prevalence of fecal carriage of multidrug-resistant GNB, including ESBLs, carbapenemases, and cephalosporinases producing bacteria in patients hospitalized in ICU.

Community fecal carriage of broad-spectrum cephalosporin-resistant Escherichia coli in Tunisian children.

The spread of extended spectrum ß-lactamases (ESBL) and plasmid mediated AmpC ß-lactamases (pAmpC) was evaluated in Escherichia coli strains collected from the intestinal microbiota of healthy children in Tunisia. The carriage rate of CTXRE. coli was 6.6% (7 of 105 samples) and one strain/sample was further characterized (7 isolates). These isolates harbored blaCTX-M-1 (n = 4), blaCTX-M-15 (n = 2), and blaCMY-2 gene (n = 1), which were usually located on FIB replicon type and carried class 1 integrons. The acc(6')-Ib-cr variant was identified in one isolate that harbored blaCTX-M-15. CTXRE. coli isolates were genetically unrelated and belonged to B1 (n = 3/ST155/ST398/ST58), D (n = 2/ST117/ST493), B2 (n = 1/ST127), and A (n = 1/ST746) phylogroups. Strain virulence scores varied from 3 to 12, and frequently harbored the pathogenicity island PAI IV536. The intestinal tract of healthy children constitute an important reservoir of ESBL producing E. coli. Thus, improvement of hygiene measures mainly in the school environment and rational use of antibiotics would be of great help in preventing selection and diffusion of resistant strains from intestinal microbiota.

High Prevalence of Gut Microbiota Colonization with Broad-Spectrum Cephalosporin Resistant Enterobacteriaceae in a Tunisian Intensive Care Unit.

Healthcare-associated infections due to cefotaxime-resistant (CTX-R) Enterobacteriaceae have become a major public health threat, especially in intensive care units (ICUs). Often acquired nosocomially, CTX-R Enterobacteriaceae can be introduced initially by patients at admission. This study aimed to determine the prevalence and genetic characteristics of CTX-R Enterobacteriaceae-intestinal carriage in ICU patients, to evaluate the rate of acquisition of these organisms during hospitalization, and to explore some of the associated risk factors for both carriage and acquisition. Between December 2014 and February 2015, the 63 patients admitted in the ICU of Charles Nicolle hospital were screened for rectal CTX-R Enterobacteriaceae colonization at admission and once weekly thereafter to identify acquisition. CTX-R Enterobacteriaceae fecal carriage rate was 20.63% (13/63) at admission. Among the 50 non-carriers, 35 were resampled during their hospitalization and the acquisition rate was 42.85% (15/35). Overall, 35 CTX-R Enterobacteriaceae isolates were collected from 28 patients (25 Klebsiella pneumoniae, seven Escherichia coli, and three Enterobacter cloacae strains). Seven patients were simultaneously colonized with two CTX-R Enterobacteriaceae isolates. CTX-M-15 was detected in most of the CTX-R Enterobacteriaceae isolates (30/35, 88.23%). Three strains co-produced CMY-4 and 22 strains were carbapenem-resistant and co-produced a carbapenemase [OXA-48 (n = 13) or NDM-1 (n = 6)]. Molecular typing of K. pneumoniae strains, revealed eight Pulsed field gel electrophoresis (PFGE) patterns and four sequence types (ST) [ST101, ST147, ST429, and ST336]. However, E. coli isolates were genetically unrelated and belonged to A (n = 2), B1 (n = 2) and B2 (n = 3) phylogenetic groups and to ST131 (two strains), ST572 (two strains), ST615 (one strain) and ST617 (one strain). Five colonized patients were infected by CTX-R Enterobacteriaceae (four with the same strain identified from their rectal swab and one with a different strain). Whether imported or acquired during the stay in the ICU, colonization by CTX-R Enterobacteriaceae is a major risk factor for the occurrence of serious nosocomial infections. Their systematic screening in fecal carriage is mandatory to prevent the spread of these multidrug resistant bacteria.

High prevalence of extended-spectrum and plasmidic AmpC beta-lactamase-producing Escherichia coli from poultry in Tunisia.

This study was conducted to detect extended spectrum beta-lactamases (ESBLs) and plasmidic AmpC beta-lactamase (pAmpC-BL)-producing Escherichia coli isolates in industrial poultry samples were collected from healthy chickens of the three farms. Samples were inoculated onto desoxycholate-lactose-agar plates supplemented with cefotaxime (2mg/L). E. coli was identified by biochemical and molecular methods and antibiotic susceptibility testing by the disk diffusion method. Genes encoding ESBLs and pAmpC-BL were detected by PCR and sequencing. Phylogenetic groups were determined by triplex PCR. The molecular typing of strains was done by pulsed field gel electrophoresis (PFGE) and Multilocus Sequence Typing (MLST) in those isolates showing different PFGE patterns. Cefotaxime-resistant E. coli isolates were recovered in 48 of 137 fecal samples (35%), and one isolate/sample was further studied. The following beta-lactamase genes were detected: blaCTX-M-1 (29 isolates, isolated in all three farms), blaCTX-M-15 (5 isolates, confined in farm II), blaCTX-M-14 and blaCMY-2 (one isolate and 13 isolates, respectively, in farm III). The 48 cefotaxime-resistant isolates were distributed into phylogroups: B1 (n=21), A (n=15) and D (n=12). PFGE analysis revealed 19 unrelated patterns: 15 different profiles among ESBL-positive strains and 4 among the CMY-2-positive isolates. The following sequence types-associated phylogroups were detected: a) CTX-M-1-positive strains: lineages ST542-B1, ST212-B1, ST58-B1, ST155-B1 and ST349-D; b) CTX-M-15-positive strain: lineage ST405-D; c) CTX-M-14-positive strain: lineage ST1056-B1; d) CMY-2-positive strains: lineages ST117-D, ST2197-A, and ST155-B1. Healthy chickens constitute an important reservoir of ESBL- and pAmpC-BL-producing E. coli isolates that potentially could be transmitted to humans via the food chain or by direct contact.