Fecal carriage of extended-spectrum β-lactamase-producing Enterobacteriaceae in community setting in Casablanca

BACKGROUND

The importance of community-acquired infections due to extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-PE) has been increasingly recognized in recent years. This study aimed to determine the prevalence of intestinal carriage of ESBL-PE in the community in Casablanca, Morocco.

METHODS

During 6 months (2013), 93 fecal samples were examined for ESBL-PE. Isolates expressing an ESBL phenotype were investigated for the presence of genes encoding β-lactamases and plasmid-mediated quinolone resistance. Conjugation experiments were done to determine the mobility of ESBL genes.

RESULTS

The prevalence of fecal carriage of ESBL-PE was 4.3% (4/93; 95% CI, 0.2-8.4). Klebsiella pneumoniae (n = 2), Enterobacter cloacae (n = 2), Escherichia coli (n = 1), and Serratia odorifera (n = 1) were the ESBL-producing species. Four (66.7%) of these isolates were multidrug-resistant. The blaSHV-12 (n = 5) was the most frequent ESBL gene detected, followed by blaCTX-M-15 (n = 3).The non-ESBL gene detected was blaTEM-1 (n = 5). One isolate harbored the qnrB1 variant. RESULTS of conjugation experiments indicated that blaSHV-12 + blaTEM-1 + qnrB1 and blaCTX-M-15 + blaTEM-1 genes were co-transferred and that these genes were carried by a conjugative plasmid of high molecular weight (125 kb).

CONCLUSION

Our results show the importance of the intestinal tract as a reservoir for ESBL-PE in the community in Morocco.

Phenotypic and Molecular Characterization of Extended-Spectrum β-Lactamase Produced by Escherichia coli, and Klebsiella pneumoniae Isolates in an Educational Hospital

Background:

Extended-spectrum beta-lactamases (ESBLs) are a group of enzymes that hydrolyze antibiotics, including those containing new cephalosporins, and they are found in a significant percentage of Escherichia coli and Klebsiellapneumoniae strains. With the widespread use of antibiotics, difficulties with infection therapy caused by drug resistant organisms, especially those that have acquired resistance to beta-lactams, such as broad-spectrum cephalosporins, have amplified the above-mentioned organisms.

Objectives:

This study was conducted to characterize ESBLs among E. coli and K. pneumonia isolates by molecular and phenotypic methods.

Materials and Methods:

Different strains of E. coli and K. pneumonia were collected from patients with urinary tract infections. The ESBL phenotype was determined by a double disk diffusion test (DDDT). In addition, polymerase chain reaction (PCR) analysis specific for β-lactamase genes of the TEM and SHV family was carried out. The PCR products were run on agarose and examined for DNA bands.

Results:

A total of 245 E. coli and 55 K. pneumonia strains were isolated from different samples. In total, 128 of the 300 isolates were confirmed as potential ESBLs producers as follows: 107 (43.67%) E. coli and 21 (38.18%) K. pneumonia. ESBLs genes were found in 24 isolates (18.75%): 21 E. coli and 3 K. pneumonia isolates. The TEM gene was present in 13 (12.14%) E. coli strains, but it was not detected in K. pneumonia. In addition, the SHV gene was present in 8 (7.47%) E. coli and 3 (14.28%) K. pneumonia isolates. Five (4.67%) of the E. coli isolates harbored both TEM and SHV genes. All isolates (100%) were susceptible to imipenem. The lowest rates of resistance to other antibiotics were observed for; piperacillin-tazobactam (6.25%), amikacin (12.5%) and gentamicin (14.84%). The rates of resistance to other antibiotics were as follow: nitrofurantoin (16.4%), nalidixic acid (23.43), co-trimoxazole (25%), cefepime (32%), ciprofloxacin (55.46%), ampicillin (69.53%), ceftazidime (100%), and cefotaxime (100%).

Conclusions:

The results of this study indicate the widespread prevalence of ESBLs and multiple antibiotic resistance in E. coli and K. pneumoniae. Therefore, beta-lactam antibiotics and beta-lactamase inhibitors or carbapenems should be prescribed based on an antibacterial susceptibility test.

ESBL-producing Enterobacteriaceae in Africa - a non-systematic literature review of research published 2008-2012

INTRODUCTION

Enterobacteriaceae producing extended-spectrum beta-lactamases (ESBL) has been found all over the world, and risk factors for acquiring these bacteria involve hospital care and antibiotic treatment. Surveillance studies are present in Europe, North America, and Asia, but there is no summarizing research published on the situation in Africa.

AIM

This review aims to describe the prevalence of ESBL-producing Enterobacteriaceae in hospital and community settings in Africa and the ESBL genes involved.

METHOD

A non-systematic literature search was performed in PubMed. All articles published between 2008 and 2012 were screened and read in full text. Relevant articles were assessed for quality of evidence and included in the review. Articles were divided into regional areas in Africa and tabulated.

RESULTS

ESBL-producing Enterobacteriaceae in hospitalized patients and in communities varies largely between countries and specimens but is common in Africa. ESBLs (class A and D) and plasmid-encoded AmpC (pAmpC) were regularly found, but carbapenemases were also present.

CONCLUSION

ESBL-producing Enterobacteriaceae in hospital and community settings in Africa is common. Surveillance of antimicrobial resistance needs to be implemented in Africa to tailor interventions targeted at stopping the dissemination of ESBL-producing Enterobacteriaceae.

Phenotypic and Genetic Characterization of Carbapenemase and ESBLs Producing Gram-negative Bacteria (GNB) Isolated from Patients with Cystic Fibrosis (CF) in Tehran Hospitals

BACKGROUND

Cystic Fibrosis (CF) is an autosomal recessive genetic disorder in white populations caused by mutation in a gene that encodes Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) protein. Since frequent respiratory tract infections are the major problem in patients with CF, obligation to identify the causative bacteria and determining their antibiotic resistance pattern is crucial. The purpose of this project was to detect Gram-negative bacteria (GNB) isolated from sputa of CF patients and to determine their antibiotic resistance pattern.

MATERIALS AND METHODS

The sputum of 52 CF patients, treated as inpatients at hospitals in Tehran, was obtained between November 2011 and June 2012. Samples cultured in selective and non-selective media and GNB recognized by biochemical tests. Antimicrobial susceptibility testing to cephalosporins, aminoglycosides and carbapenems was performed by disk diffusion method and MICs of them were measured. For phenotypic detection of carbapenemase and ESBLs production, the Modified Hodge test, double disk synergy test and the combined disk methods were performed. Subsequently, the genes encoding the extended spectrum beta-lactamases (blaPER, blaCTX-M) and carbapenemases (blaIMP-1, blaGES, blaKPC, blaNDM, blaVIM-1, blaVIM-2, blaSPM, blaSIM) in Gram negative bacteria were targeted among the resistant isolates by using PCR. PFGE was used to determine any genetic relationship among the Pseudomonas aeruginosa isolated from these patients.

RESULTS

Fifty five GNB were isolated from 52 sputum samples including Pseudomonas aeruginosa, Klebsiella ozaenae, Alcaligenes xylosoxidans, Achromobacter denitrificans, Klebsiella pneumonia and Stenotrophomonas maltophilia. The rates of resistance to different antibiotic were as follows: cefixime (%80), ceftriaxone (%43), ceftazidime (%45) and meropenem (%7). The prevalence of genes encoding the ESBLs and Carbapenemases among the the phenotypically positive strains were as follows: blaCTX-M (19), blaIMP-1 (2), blaVIM-1 (2) and blaVIM-2 (3) genes respectively. No other genes were detected. PFGE analysis revealed 8 genotypes. Six isolates had mutually 3 similar patterns.

CONCLUSION

This study showed the existence of important ESBLs and carbapenemases genes among the GNB isolated from patients with CF. Continuous surveillance of ESBLs and Carbapenemases, also identification of their types, in bacteria isolated from these patients have an important clinical impact, since, it can often provide valuable information for effective infection control measures and for the choice of appropriate antimicrobial therapy.

PCR-Based Detection of Extended-Spectrum β-Lactamases (bla CTX-M-1 and bla TEM ) in Escherichia coli, Salmonella spp. and Klebsiella pneumoniae Isolated from Pigs in North Eastern India (Mizoram)

Cephalosporins are major antimicrobials used to treat serious infections. However, their effectiveness is being compromised by the emergence of extended-spectrum β-lactamases (ESBLs). A total of 138 enteric bacteria were isolated from 53 faecal samples of pigs collected from different districts of Mizoram, of which 102 (73.91 %) were Escherichia coli, 26 (18.84 %) were Salmonella spp. and 10 (7.25 %) were Klebsiella pneumoniae. Phenotypic confirmatory test (Double Discs Synergy Test) showed that 8 (5.80 %) E. coli isolates were ESBLs producer. PCR analysis confirmed that out of the eight isolate, 7 (5.07 %) harboured bla CTX-M-1 gene and/or bla TEM gene. Of the eight positive isolates, 7 (5.07 %) and 3 (2.17 %) were found to be positive for bla CTX-M-1 gene and bla TEM gene, respectively, of which 3 (2.17 %) isolates were positive for both the genes. Only 4 (2.90 %) E. coli isolates carried bla CTX-M-1 gene alone. Agarose gel electrophoresis showed that all the isolates were carrying plasmids ranging between 0.9 and ~30 kb. Out of the seven isolates positive for bla CTX-M-1 and/or bla TEM , 2 (1.84 %) isolates were confirmed for bla CTX-M-1 gene in their plasmid. Only one E. coli isolate was found to be positive for both the genes in its plasmid. The resistance plasmid could not be transferred to a recipient by in vitro horizontal gene transfer method.

Prevalence and genotypic analysis of plasmid-mediated β-lactamases among urinary Klebsiella pneumoniae isolates in Moroccan community

The aim of this study is to assess the prevalence and molecular characterization of the extended spectrum β-lactamases (ESBL)-producing Klebsiella pneumoniae isolated from community acquired urinary tract infections and collected in five Moroccan cities during a 2010 survey. In all, 34 (7.5%) of the 453 K. pneumoniae isolates studied were positive for an ESBL phenotype and 91.1% of these isolates were multidrug resistant. The bla(CTX-M-15) (n=31) was the most frequent ESBL genes detected, followed equally by bla(SHV-28) and bla(SHV-12) (n=3), then bla(TEM-3), bla(SHV-36), bla(SHV-110) and bla(CTX-M-1) with one isolate for each (n=1). Eight isolates co-expressed more than one ESBL with bla(CTX-M-15). The non-ESBL genes detected were bla(SHV-1), bla(SHV-11), bla(SHV-32), bla(SHV-26), bla(SHV-76), bla(TEM-1), bla(TEM-1b) and bla(OXA-1). Plasmid-mediated AmpC β-lactamase genes, bla(ACT-2), bla(DHA-1) and a new β-lacatamase named bla(EBC-1464), were detected in 11.7% of isolates. Fourteen (41.1%) isolates harbored qnr genes; qnrA6 (n=1), qnrB1 (n=8), qnrB2 (n=1) and qnrS1 (n=4) types were detected. Twenty-six isolates (76.4%) were positive for aac(6')-Ib-cr gene. Results of conjugation experiments indicated that bla(CTX-M-15), bla(TEM-1b), bla(OXA-1), aac(6')-Ib-cr and qnrB1 genes were co-transferred and that these genes were carried by a conjugative plasmid of high molecular weight. With the exception of qnrB1, all the antibiotic resistance genes were clustered in a 12-kb region. The results of this work report the genetic diversity of ESBL genes, with the CTX-M-15 enzyme being most common among ESBL-producing K. pneumoniae in Moroccan community. Furthermore, a major finding is that bla(EBC-1464) detection is a first in Morocco.

Plasmid-mediated quinolone resistance in extended-spectrum-β-lactamase- and AmpC β-lactamase-producing Serratia marcescens in China

We investigated the prevalence of plasmid-mediated quinolone resistance (PMQR) determinants and examined the association of these determinants with extended-spectrum β-lactamases (ESBLs) and/or plasmid-mediated AmpC β-lactamases (pAmpCs) in Serratia marcescens isolates in China. In this study, the presence of PMQR determinants was significantly related to the coproduction of ESBLs and/or pAmpCs (CTX-M-14, SHV-5, DHA-1, and ACT-1), among which CTX-M-14 was the most common gene type.

High prevalence of acquired quinolone-resistance genes among Enterobacteriaceae from Saudi Arabia with CTX-M-15 β-lactamase

We examined the prevalence of acquired quinolone resistance determinants among Enterobacteriaceae with extended-spectrum β-lactamases (ESBLs) in Riyadh, Saudi Arabia. qnrA, qnrB, qnrS, aac(6')-Ib-cr, and qepA genes were sought by polymerase chain reaction (PCR) in 160 nonduplicate, clinical Enterobacteriaceae with ESBLs from Prince Salman Hospital in Riyadh during 2009. MICs were determined for qnr- and aac(6')-Ib-cr-positive isolates. Mutations in gyrA and parC were determined for isolates with qnr. ESBL genes were characterized by PCR and sequencing. Among 99 ESBL-producing Escherichia coli, 73% were ciprofloxacin resistant, as were 74% of 61 ESBL-positive Klebsiella pneumoniae. The aac(6')-1b-cr gene was present in 76 ESBL producers, comprising 34 K. pneumoniae and 42 E. coli, whereas qnrA or qnrB genes were found in 21 isolates, all of them also harbouring aac(6')-1b-cr and bla(CTX-M-15), with the latter encoding what was considerably the dominant ESBL in the collection. The qnr-positive isolates harboured a variety of mutation in gyrA and parC but, even with aac(6')-1b-cr also present, high-level ciprofloxacin resistance (MIC >32 μg/mL) was invariably associated with double mutations in gyrA, affecting both Ser83 and Asp87 along with >1 substitution in parC, affecting Ser80 or Glu84.

Contribution of IncFII and broad-host IncA/C and IncN plasmids to the local expansion and diversification of phylogroup B2 Escherichia coli ST131 clones carrying blaCTX-M-15 and qnrS1 genes

The recent increase of CTX-M-15-producing Escherichia coli isolates in our institution was caused by diverse clonal backgrounds, including mainly B2 sequence type 131 (ST131) clones presenting variable virulence profiles but also A(1) (ST617, ST410), B1, and D(1) (ST405) clones. Besides IncFII-pC15-1a, we detected multidrug-resistant IncA/C(2) and IncN plasmids carrying bla(CTX-M-15) and/or qnrS1. Our study highlights the diversification of highly transmissible resistant and virulent clones and the recombinogenic potential of broad-host plasmids contributing to the expansion of genetic regions coding for multidrug resistance to other bacterial lineages.