Plasmid-mediated quinolone resistance in expanded spectrum beta lactamase producing enterobacteriaceae in Morocco

Introduction: Although independently acquired, plasmid-mediated quinolone resistance appears to be linked with extended-spectrum or AmpC-type beta-lactamases. Since no data are available in African countries, the prevalence of qnr genes at the University Hospital Ibn Rochd, Casablanca, Morocco, was investigated. Methodology: Between October 2006 and March 2007, the following 39 randomly selected non-duplicate Enterobacteriaceae producing an extended-spectrum beta-lactamase (ESBL), representing 20% of ESBL strains with respect to species and ward origin, were collected: Escherichia coli (n = 16); Klebsiella spp (n = 14); Enterobacter cloacae (n = 8); Proteus mirabilis (n = 1). Antibiotic susceptibility testing was performed according to CLSI guidelines. ESBL detection was performed by the double disc diffusion test. A multiplex PCR was conducted to detect qnrA, qnrB and qnrS genes that were confirmed by sequencing of the PCR product. Results: The estimated overall prevalence of qnr reached 36% (n = 14; qnrA, 10.25%; qnrB, 23.07%; qnrS, 2.56%). Genes were identified in E. coli, Klebsiella and Enterobacter with a respective prevalence of 18.7%, 50% and 62.5%.  The qnr genes were detected in nine wards and qnrA1, qnrB1-B2-B4 and qnrS1 variants were identified. Three genes were identified among nalidixic acid susceptible strains (n = 6); three of those were also susceptible to ciprofloxacin. Among nalidixic acid and ciprofloxacin resistant strains, all strains had qnrB. Conclusions: This study highlights the high prevalence of qnr genes among ESBL strains in the Ibn Rochd CHU, Casablanca. Moreover, qnr were present in quinolone-susceptible strains which could lead to in vivo selection of ciprofloxacin-resistant strains.

Prevalence and antibiotic-resistance of Salmonella isolated from food in Morocco

BACKGROUND

Salmonellosis remains one of the most frequent food-borne diseases worldwide, especially in developing countries. The emergence of antimicrobial resistance in Salmonella isolates from food can potentially compromise the treatment of these infections. This investigation was conducted for the first time in Morocco both to detect the occurrence of Salmonella in foods as well as to determine the antibiotic resistance profile of the Salmonella isolates.

METHODOLOGY

In total, 11,516 food samples collected from 2002 to 2005 were investigated. Isolated Salmonella were characterized by serotyping and susceptibilities were determined for 15 antimicrobial drugs using the disc diffusion assay.

RESULTS

The overall percentage of Salmonella prevalence (n=105) was 0.91% with rates of 71% for slaughterhouses and 9% for seafood. Sixteen different serotypes were identified among 104 Salmonella enterica isolates including serotypes Infantis (n=25), Bredeney (n=13), Blokley (n=11), Typhimurium (n=9), Mbandaka (n=8), Branderup II (n=7), and Kiambu (n=6); 1 isolate of Salmonella enterica belonged to subspecies II salamae. Twenty-nine percent of isolates (n=30/105) were resistant to at least one antimicrobial. Resistance to tetracycline was the most common finding (21%), followed by resistance to ampicillin (13%), amoxicillin+clavulanic acid (9%), streptomycin (7%), chloramphenicol (4%) and nalidixic acid (3,8%). None of the isolates was resistant to 3rd-cephalosporin and fluoroquinolones (i.e. ciprofloxacin). Multidrug resistance (MDR) was seen in 9.5% of the isolates, mainly in S.. Typhimurium DT104 with R-type ACSSuT and S. Hadar.

CONCLUSIONS

Despite a low frequency of Salmonella isolation, S. Typhimurium DT104 was identified in the first step of the food chain. The study points out the need control antibiotic resistance in Salmonella isolated from food in Morocco to avoid the spread of MDR.

Rapid detection of Listeria monocytogenes in food by polymerase chain reaction

The standard conventional methods for the detection of Listeria monocytogenes in foods require high time 7 to 10 days to give ready results. To dissolve this problem we have evaluate a short method using Polymerase Chain Reaction (PCR) to analyze food samples. In parallel with this study, a comparison was made between PCR amplification from templates directly prepared from food and the official standard ISO procedure 11290-1. In this study we have used a Half Frazer broth as an enrichment medium; there were positive results of PCR detection of L. monocytogenes in different food sample analyzed (milk, cheese and meat) with approximately 1.5 10(1) Colony Forming Units /25 g in less than 36 h. This PCR procedure has proved to be rapid and sensitive method suitable for the routine analysis; firstly, because this assay required just a short pre-enrichment step before PCR. Secondly, this procedure is very simple and time-saving; it could take less than one working day to obtain results if initial microbiological load was very important.

Characterization and antibiotic susceptibility of Listeria monocytogenes isolated from poultry and red meat in Morocco

This study was carried out on 426 samples of raw meats collected from butcheries and supermarkets in Casablanca, Morocco. The samples were examined for the occurrence of Listeria species. Strains of Listeria monocytogenes were characterized by several biochemical tests and confirmed by polymerase chain reaction (PCR). β-hemolytic cultures and nonhemolytic isolates were tested for biochemical properties with the Listeria API test. Among the 43 Listeria species isolates; we identified 10 strains for L. monocytogenes (23.3%), 31 strains for L. innocua (72.1%) and 2 strains for L. welshimeri (4.6%). Strains of L. monocytogenes were separated by multiplex PCR; two serogroups IIb and IVb were thus differentiated. Antibiotic susceptibility of L. monocytogenes to 21 antibiotics was determined by the disk diffusion method. All isolates were susceptible to a wide range of the tested antibiotics with the exception of nalidixic acid, colistine and cephalosporins second and third generation for which they were all resistant.

Ceftriaxone-resistant salmonella enterica serotype Newport, France

The multidrug-resistant (MDR) Salmonella enterica serotype Newport strain that produces CMY-2 beta-lactamase (Newport MDR-AmpC) was the source of sporadic cases and outbreaks in humans in France during 2000-2005. Because this strain was not detected in food animals, it was most likely introduced into France through imported food products.

Association between plasmid carrying an expanded-spectrum cephalosporin resistance and biofilm formation in Escherichia coli

The formation of biofilm is a universal bacterial survival strategy. Biofilms occur on inert and living support in the natural environment and in industrial installations. This microenvironment leads to the horizontal transfer of genetic material between bacteria by physical contact. In order to evaluate the relationship between biofilm-forming capabilities, surface characteristics and plasmid content we purified from Salmonella a plasmid conferring resistance to cephalosporin and transferred it by electroporation to E.coli DH10B originally unable to form biofilm in inert surface. We demonstrated the association between a plasmid conferring resistance to expanded-spectrum cephalosporin and biofilm formation. We also noted that this plasmid influences the cell surface properties and cell motility.

Study of the RET gene and his implication in thyroid cancer: Morocco case family

BACKGROUND

Multiple endocrine neoplasia type 2A (MEN 2A) is an autosomal dominant inherited cancer syndrome that affects multiple tissues derived from the neural crest. Inheritance of MTC is related to the presence of specific mutations in the RET proto-oncogene. Almost all mutations in MEN 2A involve one of the cysteines in the extracellular domain of the RET receptor.

AIMS

The objective of the present study was the biochemical and molecular characterization of the first Moroccan clinically established MEN 2A patient and at-risk family members.

SETTINGS AND DESIGN

This is a study on a family presented with MTC referred to our institute in 2004.

MATERIALS AND METHODS

Peripheral blood leukocyte DNA samples were isolated and amplified by polymerase chain reaction followed by restriction enzyme analysis and DNA sequencing.

RESULTS

We identified a heterozygous germ line missense mutation at codon 634 of exon 11 in the RET gene that causes a cysteine to arginine amino acid substitution in the DNA of the proband; this mutation was not found in the DNA of the parents or relatives.

CONCLUSIONS

The detection of mutated MEN 2A gene carriers enables us to differentiate high-risk members from those who bear the wild-type gene. Occasionally, application of RET proto-oncogene testing may lead to the detection of unexpected de novo mutation that could be transmitted to children.

Treatment evaluation, follow-up and familial screening of medullary thyroid carcinoma by highly specific calcitonin measurements

BACKGROUND

Calcitonin is the most sensitive and specific marker for medullary thyroid carcinoma (MTC).

AIMS

The aim of this study was to emphasize the role and the limits of plasma basal calcitonin (bCT) measurement in the management of Moroccan MTC patients and their relatives.

SETTINGS AND DESIGN

This is a retrospective study on 6 MTC patients referred to our institute from January 1996 to December 2004.

MATERIALS AND METHODS

Serum bCT levels were measured in 36 individuals comprising six known MTC cases, 18 relatives and 12 healthy volunteers, using two-sites immunoradiometric assay method. Five of MTC patients have been followed from 12 to 96 months after surgery.

STATISTICAL ANALYSIS USED

Calculations were performed using SPSS 10.0 program. Data comparison was done by Student's t -test.

RESULTS

The circulating preoperative bCT concentrations were elevated for all MTC patients (range, 44,8 -2055 pg/ml, normal <10). Recent postoperative bCT determinations varied from 24.4 to 1972 pg/ml in four patients. In one patient, the bCT value decreased to an undetectable level during a follow-up of 12 months. The mean bCT level of relatives was 4.90 +/- 3.54 pg/ml; two patients had slightly elevated bCT. Five (42%) healthy volunteers had undetectable bCT levels and all had less than 10 pg/ml; the mean bCT value was 3.06 +/- 2.51 pg/ml.

CONCLUSIONS

Routine plasma bCT measurement still has an important place in the preoperative diagnosis and follow-up treatment of MTC.

Multidrug resistance in Salmonella enterica serotype Typhimurium from humans in France (1993 to 2003)

The aim of this study was to determine the distribution of the antimicrobial resistance phenotypes (R types), the phage types and XbaI-pulsed-field gel electrophoresis (PFGE) types, the genes coding for resistance to beta-lactams and to quinolones, and the class 1 integrons among a representative sample of Salmonella enterica serotype Typhimurium isolates collected from humans in 2002 through the French National Reference Center for Salmonella (NRC-Salm) network. The trends in the evolution of antimicrobial resistance of serotype Typhimurium were reviewed by using NRC-Salm data from 1993, 1997, 2000, and 2003. In 2002, 3,998 isolates of serotype Typhimurium were registered at the NRC-Salm among 11,775 serotyped S. enterica isolates (34%). The most common multiple antibiotic resistance pattern was resistance to amoxicillin, chloramphenicol, streptomycin and spectinomycin, sulfonamides, and tetracycline (ACSSpSuTe R type), with 156 isolates (48.8%). One isolate resistant to extended-spectrum cephalosporins due to the production of TEM-52 extended-spectrum beta-lactamase was detected (0.3%), and one multidrug-resistant isolate was highly resistant to ciprofloxacin (MIC > 32 mg/liter). We found that 57.2% of the isolates tested belonged to the DT104 clone. The main resistance pattern of DT104 isolates was R type ACSSpSuTe (83.2%). However, evolutionary changes have occurred within DT104, involving both loss (variants of Salmonella genomic island 1) and acquisition of genes for drug resistance to trimethoprim or to quinolones. PFGE profile X1 was the most prevalent (74.5%) among DT104 isolates, indicating the need to use a more discriminatory subtyping method for such isolates. Global data from the NRC-Salm suggested that DT104 was the main cause of multidrug resistance in serotype Typhimurium from humans from at least 1997 to 2003, with a roughly stable prevalence during this period.

cut-1-like genes of Ascaris lumbricoides

Three genomic fragments homologous to cut-1 of Caenorhabditis elegans (C. elegans) have been identified in the intestinal parasitic nematode Ascaris lumbricoides (A. lumbricoides). Two of these fragments identify one region of the A. lumbricoides genome; they are separated by 8-9 kb and have opposite orientation, with the direction of transcription converging toward the center of the region. The third gene, which has been studied more completely, is in a different region of the genome separated from the first one by not less than 12-15 kb. The complete genomic sequence of this third gene has been determined. cDNA overlapping clones were obtained from adult A. lumbricoides RNA via the rapid amplification of cDNA ends (RACE) procedure [Frohman et al., 1988. Rapid production of full-length cDNAs from rare transcripts: amplification using a single gene-specific oligonucleotide primer. Proc. Natl. Acad. Sci. USA 85, 8998-9002] and sequenced. The mature mRNA of this gene, which we have named ascut-1, is trans-spliced to the spliced leader sequence of nematodes (SL1) [Krause, M., Hirsh, D., 1987. A trans-spliced leader sequence on actin mRNA in C. elegans. Cell 49, 753-761]. The mRNA is 1684 nt long plus the poly(A) tail and contains four exons with a 138 nt untranslated 5' leader and a 388 nt untranslated 3' tail. Conceptual translation of the coding sequence shows a protein of 385 aa with a signal peptide of 16 aa. The protein shows very high homology with CECUT-1, the product of the C. elegans gene cut-1 and with other cuticlin proteins of nematodes. A 262 amino acids region which is strongly conserved between these proteins seems to identify a group of proteins, so far restricted to nematodes, for which the name CUT-1-like is proposed.