Molecular epidemiology of extended-spectrum beta-lactamase-producing Klebsiella pneumoniae strains in a university hospital in Tunis, Tunisia, 1999-2005.

Laboratoire des Maladies Transmissibles et Substances Biologiquement Actives, Faculté de Pharmacie, Monastir, Tunisie.
Clinical Microbiology and Infection (Impact Factor: 4.58). 09/2009; 16(2):157-64. DOI: 10.1111/j.1469-0691.2009.03057.x
Source: PubMed

ABSTRACT During a period of 6 years and 5 months (January 1999 to May 2005), 103 extended-spectrum beta-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 bla(SHV), bla(CTX-M) and bla(TEM) 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 bla(SHV-2a) or bla(CTX-M-15) genes were assigned to IncFII or, more rarely, to IncL/M types. Of 12 plasmids carrying the bla(SHV-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 bla(CTX-M-15) and the bla(SHV-12) genes.

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    ABSTRACT: Extended-spectrum beta-lactamases (ESBLs) are plasmid-mediated beta lactamases that are capable of hydrolysing beta-lactams except carbapenems and cephamycins. The ESBL types include SHV, TEM and CTX-M, OXA, PER and VEB-1. The most common ones isolated from clinical specimen are the CTX-M, SHV and TEM. The specific ESBL-producing organisms have different genetic characteristics which mark their identification at the molecular level. This work sought to determine the genetic characterization of ESBL-producing K. pneumoniae and E. coli in Accra. The molecular investigations of the ESBL-coding genes included extraction of 100 DNA templates of phenotypic ESBL-producing isolates by boiling method, preparation of the PCR reaction mixture using appropriate primers, standard PCR reaction in a thermocycler, agarose gel electrophoresis, bands visualization by ultraviolet trans-illumination and bands photography using a Kodak EDAS 290 gel documentation system. The results significantly (p<0.05) indicated that of the 100 ESBL producers, 90(90%) possess CTX-M genes and 25(25%) had TEM genes. None of the ESBL producers possesses SHV genes. Seventy (70%) of the ESBL producers possess only CTX-M genes and 5(5%) had only TEM genes. Twenty (20%) of the isolates had both CTX-M and TEM genes. Of the 100 ESBL phenotypes, 78(78%) and 2(2%) were positive for CTX-M-1group and CTX-M-9group ESBL genes respectively. Organisms producing CTX-M-type ESBL are more prevalent in Accra than other ESBL types. CTX-M-1group producing isolates dominated the ESBL phenotypes with CTX-M-15 likely to be the dominate CTX-M-type ESBL. There is the need for further studies into the characteristic transmission, pathogenesis, antibiotic resistance expression, and infection control of CTX-M-type ESBL and TEM-type ESBL in Accra. 1.0 Introduction Extended-spectrum beta-lactamases (ESBLs) are plasmid-mediated beta lactamases that are capable of hydrolysing beta-lactams except carbapenems and cephamycins. They are inhibited by beta-lactamase inhibitors such as clavulanic acid, sulbactam and tazobactam. They have been found in the Enterobacteriaceae and other Gram-negative bacilli. ESBL producing isolates are predominantly Klebsiella pneumoniae and Escherichia coli (Paterson and Bonomo, 2005). The ESBL types include SHV, TEM and CTX-M, OXA, PER and VEB-1. The most common ESBL genes isolated from clinical specimen are the CTX-M, SHV and TEM (Paterson and Bonomo, 2005). It has been observed that the same organism may harbour two or more ESBL genes, which may change the antibiotic resistance phenotype (Yamasaki et al., 2003). The CTX-M enzymes are replacing SHV and TEM enzymes as the prevalent type of ESBLs in urinary tract infections, bloodstream and intra-abdominal infections (Falagas and Karageorgopoulos, 2009). The phylogenic study reveals five major groups of acquired CTX-M enzymes (Bonnet, 2004). The CTX-M-1group (Group I) includes CTX-M-1 , CTX-M-3 , CTX-M-10 , CTX-M-12 , CTX-M-15 , CTX-M-22 , CTX-M-23 , CTX-M-28 , CTX-M-29 CTX-M-30 and CTX-M-68 . The CTX-M-2group (Group II) includes CTX-M-2 , CTX-M-4 , CTX-M-5 , CTX-M-6 , CTX-M-7 and CTX-M-20 . The CTX-M-8group (Group III) includes one plasmid-mediated member, CTX-M-8 . The CTX-M-9group (Group IV) includes nine plasmid-mediated enzymes (CTX-M-9 , CTX-M-13 , CTX-M-14 , CTX-M-16 , CTX-M-17 , CTX-M-19 , CTX-M-21 , CTX-M-24 and CTX-M-27). The CTX-M-25group (Group V) includes the CTX-M-25 and CTX-M-26 enzymes (Bonnet, 2004). The CTX-M-15 and CTX-M-14 seems to be the most widespread globally, while many of the other CTX-M ESBLs tend to be more limited in their distribution (Heffernan et al., 2007).
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    ABSTRACT: BACKGROUND:CTX-M-15 is the dominant type of extended-spectrum β-lactamase in clinical isolates. This enzyme constitutes the most widespread enzymes in Tunisia. In this study, we were interested to understand to understand the causes of the evolutionary success of CTX-M-15 in Tunisian University hospital.METHODS:A total of of seventy-two cefotaxime-resistant Enterobacteriaceae were isolated from newborn patients at a hospital Taher sfar Mahdia in Tunisia and were characterized their genetic support by means molecular techniques.RESULTS:All the isolates producing CTX-M-15-producing clustered in various clonal groups, although most isolates belonged to sequence types ST39 (K. pneumoniae) and ST131 (E. coli). F replicons (FIA, FIB and FII) were the most frequently detected replicon types in our collection (91,66%).CONCLUSION:This is the first report of QnrB- and CTX-M-15-encoding large IncF-type conjugative plasmids in Tunisia.Pediatric Research (2014); doi:10.1038/pr.2014.153.
    Pediatric Research 10/2014; DOI:10.1038/pr.2014.153 · 2.84 Impact Factor
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    ABSTRACT: Depuis les 20 dernières années, les espèces des entérobactéries principalement Escherichia coli, Klebsiella pneumoniae et P. mirabilis ont démontré des particularités d’acquisition de plasmides exprimant les β-lactamases à spectre élargi (BLSE). Des BLSE de type CTX-M ont été isolés un peu partout dans le monde et leur fréquence a connu une augmentation spectaculaire ce qui est devenu un problème thérapeutique majeur puisqu’elle ne cesse de croître. Actuellement, on compte plus de 150 variants alléliques de CTX-M. Ces enzymes sont classées en cinq groupes phylogéniques majeurs en se basant sur leurs séquences génétiques : CTX-M-1 ; CTX-M-2, CTX-M-8, CTX-M-9, CTX-M-25 et récemment deux autres groupes supplémentaires ont été rapportés : CTX-M-74 et CTX-M-75. Cette dissémination importante de ces enzymes a conduit à une utilisation croissante des carbapénèmes. Leur dissémination mondiale communautaire et nosocomiale est très souvent associée chez E. coli à un clone virulent ST131 producteur de CTX-M-15.
    Médecine et Maladies Infectieuses 09/2014; 44(9). DOI:10.1016/j.medmal.2014.03.010 · 0.91 Impact Factor


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May 26, 2014