Clin Microbiol Infect 2010; 16: 157–164
During a period of 6 years and 5 months (January 1999 to May 2005), 103 extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae isolates, each from an individual patient or site, were collected at Mongi Slim University Hospital Centre, Tunis, Tunisia. The objectives of our work were the characterization of the bla genes encoding ESBLs, the investigation of clonal diversity of strains, and identification of the transmission modes of the resistance genes. We carried out detection by PCR and sequencing of the blaSHV, blaCTX-M and blaTEM genes, transferability studies, plasmid replicon typing, and analysis by multilocus sequence typing (MLST) on selected isolates. Forty-seven isolates were found to be producers of CTX-M-type ESBLs, of which 43 were CTX-M-15, two CTX-M-14 and two CTX-M-27. Fifty-eight isolates were producers of SHV-12, and three were producers of SHV-2a. More than one ESBL was detected in seven isolates, as five produced both CTX-M-15 and SHV-12, and two produced both CTX-M-27 and SHV-12. By a PCR-based replicon typing method, the plasmids carrying the blaSHV-2a or blaCTX-M-15 genes were assigned to IncFII or, more rarely, to IncL/M types. Of 12 plasmids carrying the blaSHV-12 gene, only one could be typed: it was positive for the HI2 replicon. The MLST results showed large genetic background diversity in the SHV-12-producing isolates and dissemination of specific clones of the CTX-M-15-producing isolates within the same ward and among wards, and suggested endemicity with horizontal dissemination of the blaCTX-M-15 and the blaSHV-12 genes.
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"This is noticeable in the Tunisian setting, where a large amount of studies are available. In two hospitals studied (study periods: 1999–2005 and 2010), ESBLs have increased from 11.7 to 77.8% among K. pneumoniae (42, 49). In other settings, the trend is not noticeable among the few studies available. "
[Show abstract][Hide abstract] ABSTRACT: 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.
This review aims to describe the prevalence of ESBL-producing Enterobacteriaceae in hospital and community settings in Africa and the ESBL genes involved.
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.
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.
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.
"ESBL genes responsible for resistance are mainly found in mobile genetic elements that can readily spread through bacterial populations [7-9]. ESBL –producing K. pneumoniae usually express resistance to various antibiotics [3,6-9], therefore their antibiotic therapy is limited to a few expensive drugs which, in most cases, are not available in developing countries. "
[Show abstract][Hide abstract] ABSTRACT: Klebsiella pneumoniae strains expressing ESBLs are a predominant cause of hospital acquired infections. Here we describe the molecular epidemiology of these isolates in a tertiary hospital in Tanzania, as potential pathogens for neonatal infections.
Between April 2009 and March 2010 all Klebsiella pneumoniae isolates with phenotypic expression Extended Spectrum Beta Lactamase (ESBL) were collected and characterized. Identification was done using in house biochemical tests in case of ambiguous results confirmation was done using API 20E. Susceptibility testing was determined using the disc diffusion method followed by specific PCR and sequencing to determine ESBL genes. Phylogenetic analysis, Pulse field gel electrophoresis (PFGE) and Multi-Locus sequence typing (MLST) to PFGE clusters representative isolates were performed to determine clones of the isolates. Conjugation and hybridization were performed to determine the location of blaCTX-M-15 gene.
A total of 92 non- repetitive ESBL producing K. pneumoniae representing 50.3% of Klebsiella pneumoniae isolates were characterized. These isolates were from blood 61 (66%), wound swab 13 (14%), urine 12 (13%) and pus 6 (7%) were analyzed. Most blood culture strains originated from neonatal unit 39/61(64%) and 22 (36%) of the blood culture isolates were from neonatal ICU. All isolates were resistant to gentamicin and 54% were resistant to ciprofloxacin. Using a similarity index of 80%, the isolates were assigned to thirteen clusters based on PFGE patterns and contained sub-clusters with identical strains indicating clonal outbreaks. Cluster X5, X7 and X8, and X9 were grouped into ST48, ST14 and ST348 respectively. Based on gyrA PCR- RFLP phylogenetic analysis all isolates were grouped as KpI. The predominant ESBL allele detected was blaCTX-M-15 which was found in 76 % of isolates, followed by blaTEM-104 (19 %), blaSHV-11 (3.2%) and blaTEM-176 (2%). The blaCTX-M-15 gene was located in multiple conjugative IncF plasmids ranging from 25kb-485kb in size.
The high prevalence of blaCTX-M-15 observed among ESBL producing K. pneumoniae in Tanzania, is possibly due to the spread of a common IncFII 145kb plasmid and of certain clones such as ST14 and ST48. Furthermore the 485kb plasmid detected is the largest plasmid reported to carry blaCTX-M-15 todate.
"In fact, all the 29 studied E. coli isolates in 2009 were producing CTX-M-15 ESBL, 2 of these were co-producing SHV-12 ESBL. In accordance with previous reports on distribution of ESBL in Enterobacteriaceae, performed in Tunisia and worldwide, we have shown that the CTX-M-15 ESBL was the most prevalent ESBL in our setting [1,2,12-15]. Recent reports indicate that worldwide dissemination of CTX-M-15 is mediated by clonally related E. coli strains, especially a specific clone of phylogroup B2, ST131 [3,4,24]. "
[Show abstract][Hide abstract] ABSTRACT: Extended-spectrum beta-lactamases (ESBLs), particularly CTX-M- type ESBLs, are among the most important resistance determinants spreading worldwide in Enterobacteriaceae. The aim of this study was to characterize a collection of 163 ESBL-producing Escherichia coli collected in Tunisia, their ESBL-encoding plasmids and plasmid associated addiction systems.
The collection comprised 163 ESBL producers collected from two university hospitals of Sfax between 1989 and 2009. 118 isolates harbored blaCTX-M gene (101 blaCTX-M-15 gene and 17 blaCTX-M-14 gene). 49 isolates carried blaSHV-12 gene, 9 blaSHV-2a gene and only 3 blaTEM-26 gene. 16 isolates produced both CTX-M and SHV-12. The 101 CTX-M-15-producing isolates were significantly associated to phylogroup B2 and exhibiting a high number of virulence factors. 24 (23.7%) of the group B2 isolates belonged to clonal complex ST131. Pulsed-field gel electrophoresis (PFGE) typing revealed a genetic diversity of the isolates. 144 ESBL determinants were transferable mostly by conjugation. The majority of plasmid carrying blaCTX-M-15 genes (72/88) were assigned to various single replicon or multireplicon IncF types and had significantly a higher frequency of addiction systems, notably the VagCD module.
This study demonstrates that the dissemination of CTX-M-15 producing E. coli in our setting was due to the spread of various IncF-type plasmids harboring multiple addiction systems, into related clones with high frequency of virulence determinants.