Chromosomal bla CTX-M-15 associated with ISEcp1 in Proteus mirabilis and Morganella morganii isolated at the Military Hospital of Tunis, Tunisia

Abstract

This study investigated the genetic environment of bla CTX-M genes and associated resistance genes in seven Proteus mirabilis and six Morganella morganii extended spectrum b-lactamase (ESBL)-positive isolates. The isolates were recovered from hospitalized patients with respiratory or urinary tract infections at the Military Hospital of Tunis, Tunisia. Twenty-one of the 200 strains exhibited non-susceptibility to third generation cephalosporins and, among these strains, the double-disk synergy test confirmed the ESBL phenotype in 13 isolates. These ESBL producers were co-resistant to chloramphenicol, tetracycline and oflaxacin but remained susceptible to ertapenem (MIC,0.25 mg l "1 ). The presence and nature of bla CTX-M-15 , bla CTX-M-8 , bla TEM-24 , bla TEM-1 and bla TEM-2 genes was determined by PCR and sequencing. Chromosomal localization of the bla CTX-M-15 gene was confirmed in all strains, with the exception of M. morganii isolate M-17991, by Southern-blot analysis performed either on chromosomal or plasmid DNA. M. morganii M-12012 and M. morganii M-6019 showed the same PFGE pattern, whereas the remaining CTX-M-15-producing isolates were unrelated. The presence of ISEcp1 was ascertained in CTX-M-15-producing isolates. A class 1 integron with different gene cassettes (dfrA1, orfC and aadB) was found in five P. mirabilis and six M. morganii isolates. INTRODUCTIONCTX-M b-lactamases are the most widespread enzymes, with a growing prevalence in different members of the Enterobacteriaceae family worldwide (Livermore et al., 2007). They are not confined to only human isolates but are also present in animal and environmental bacteria (Nordmann et al., 2008; Díaz et al., 2010; Dolejska et al., 2011). The genes encoding these enzymes have been found in Escherichia coli, Klebsiella pneumoniae and Salmonella enterica. The penetration of bla CTX-M genes to many bacterial populations could be a consequence of the extraordinary dissemination of these genes by mobile elements, including plasmids, transposons and insertion sequences (IS) (ISEcp1 or ISCR1). In several reports, the role of ISEcp1-like sequences in the spread and expression of bla CTX-M genes has been ascertained (Poirel et al., 2003;Nordmann et al., 2008). ISEcp1 mobilizes the downstreamlocated gene by a transposition mechanism and also provides a strong promoter for high-level expression of bla CTX-M (Poirel et al., 2003). In this study, we investigated the genetic elements associated with the bla CTX-M-15 gene and described the surrounding sequences that included three IS elements, ISEcp1, IS26 and IS903 in seven Proteus mirabilis and six Morganella morganii extended spectrum b-lactamase (ESBL)-positive isolates recovered from the Military Hospital of Tunis. METHODSA total of 200 P. mirabilis (n5120) and M. morganii (n580) isolates were obtained from different hospitalized patients in the Military Hospital of Tunis, Tunisia, from May 2005 to June 2009. The isolates were collected from various pathological specimens, which included urine (33 %), blood (24...

Dissemination and genetic support of broad-spectrum beta-lactam-resistant <i>Escherichia coli</i> strain isolated from two Tunisian hospitals during 2004-2012

“…Conjugation experiments were carried out with E. coli HB101, as previously described 7,24 . (31; 9;3;4).…”

“…The double-disk synergy test was used to detect the ESBL production as previously described 30,24 by using amoxicillin-clavulanate against cefotaxime, ceftriaxone, ceftazidime and aztreonam. Minimum inhibitory concentrations (MICs) of selected anti-microbial agents were determined by using the dilution method on Mueller-Hinton agar according to CLSI guidelines 29 .…”

“…, and the first report of the CTX-M-15 in Tunisia was cited in the Charles Nicolle Hospital in 1984 and it was described in various studies in Tunisia including that of coque et al, the gene has been found in E. coli strains in a Tunisian Hospital 17 , France 18 , and Central African Republic [19][20][21][22][23][24][25] .91% of the ESBL-producing isolates carried blaCTX-M-15 genes…”

“…The insertion sequence ISEcp1 was found to be involved in the mobility of blaCTX-M,was located upstream the bla CTX-M-27 gene e in a neonatal ward of the maternity department of Farhat Hached Hospital, Sousse 26 .It has been found also upstream the CTX-M-14 producing E. coli isolated from hospitalized patients in a university Hospital of Tunisia 27 ., and upstream the CTX-M-15 gene in Proteus mirabilis and Morganella morganii isolated at the Military Hospital of Tunis 24 . ISEcp1 was located upstream of the blaCTX-M gene on E. coli isolates from food samples 28 .…”

Caracterização de bactérias gram-negativas multirresistentes produtoras de &#946;-lactamase-de-espectro-extendido (ESBL) em cavalos saudáveis e doentes.

“…After several attempts, the PFGE tests were unsuccessful and one sample (P.mirabilis -101B-ICB) could not be evaluated using S1 enzyme. According to reports, the location of bla CTX-M-15 in Proteus mirabilis tests confirmed chromosomal location in some isolates (Mahrouki et al, 2012;Navon-Venezia et al, 2008;Song et al, 2011 Caratolli, 2009) and this incompatibility group has contributed significantly to the success of these genes (Livermoore et al, 2007;Matthers et al, 2015). Garcia-Fernandez, Caratolli, 2010).…”