Dynamics of norovirus genotype change and early characterization of variants in children with diarrhea in central Tunisia, 2001-2012.

Human noroviruses (HuNoVs), especially GII.4 strains, are a major cause of gastroenteritis epidemics in both children and adults. Stool samples were collected from 113 Tunisian children with acute gastroenteritis in 2001 and 2002 and were retrospectively tested for HuNoVs. Fifteen (13.2%) of the 113 samples were positive for HuNoVs, all of which were genogroup II strains, and the GII.4-2004/Hunter variant was predominant (67%). We reconstituted the temporal circulation of HuNoV strains in central Tunisia between 2003 and 2012 using HuNoV isolates reported in our previous studies. A comparative analysis showed a dynamic change in the molecular profile of the HuNoV strains over a 12-year period. We found that GII.4-2004/Hunter strains were circulating as early as June 2002 and that GIX.1[GII.P15] HuNoVs were already circulating four years before this genotype was first reported in Japan in 2006. Our data suggest that epidemic strains of HuNoV circulate for several years in the pediatric population before becoming predominant. This study suggests that children from low-income countries with poor sanitation may play a significant role in the molecular evolution of noroviruses and the global emergence of new epidemic strains.

Clonal lineages detected amongst tetracycline-resistant meticillin-resistant Staphylococcus aureus isolates of a Tunisian hospital, with detection of lineage ST398.

Tetracycline resistance has been postulated as a potential phenotypic marker of livestock-associated lineage ST398 amongst meticillin-resistant Staphylococcus aureus (MRSA) clinical isolates in some European hospitals. The objective of this study was to determine if this marker could also be applied to Maghrebian countries. In total, 99 MRSA isolates were collected in a Tunisian hospital during January 2011-October 2012, and 24 tetracycline-resistant MRSA isolates of this collection were characterized. All isolates were tested for antimicrobial resistance phenotypes and genotypes, molecular typing, and virulence genes. Multilocus sequence typing showed that the majority of the isolates (19/24) belonged to clonal complex CC8 (ST247, n = 12 isolates; ST239, n = 6 isolates; ST241, n = 1 isolate). The remaining isolates belonged to CC398 (ST398, n = 1 isolate), CC5 (ST5 and ST641, n = 2 isolates), and CC80 (ST728, n = 2 isolates). Spa typing discriminated MRSA in eight spa types: bib26 (n = 12 isolates), bib26 (n = 5 isolates), bib26 (n = 2 isolates), and bib26, bib26, bib26, bib26 and the new bib26 (n = 1 isolate each). Three agr groups were found amongst the studied isolates: agr group I (n = 20 isolates), agr group II (n = 2) and agr group III (n = 2 isolates). We report the detection of one MRSA ST398-t899 isolate in the nasal sample of a farmer patient in Tunisia, representing the first report of ST398 in humans in Africa. Tetracycline resistance seems not to be a good phenotypic marker for MRSA ST398 strains in Tunisia, where CC8 was the most prevalent lineage. Continuous efforts to understand the changing epidemiology of this micro-organism are necessary not only for appropriate antimicrobial treatment and effective infection control, but also to monitor its evolution.

vanA-containing E. faecium isolates of clonal complex CC17 in clinical and environmental samples in a Tunisian hospital.

Twenty-eight vancomycin (VA)-resistant enterococci isolated from different patients (n = 16) and also from the environment (n = 12) were recovered in a Tunisian military hospital during 2012-2013. The mechanisms of resistance to VA and to other antibiotics as well as the presence of esp and hyl virulence genes were determined in these isolates by PCR, being their clonal relationship analyzed by pulsed-field gel electrophoresis (PFGE). VA resistance mechanisms detected were as follows (species-patient/environment): vanA (Enterococcus faecium, 13/5), vanC1 (Enterococcus gallinarum, 3/0), and vanC2 (Enterococcus casseliflavus, 0/7). Most of the VA-resistant enterococci presented a multiresistance phenotype and harbored different resistance genes (erm(B), tet(M), tet(L), ant(6)-Ia, aac(6')-aph(2"), aph(3')-IIIa, and catA). The PFGE revealed the presence of 3 clones (A, B, C) and 1 closely related pattern (A1) among the 13 vanA-containing E. faecium isolates of patients showing 11 of them the A-A1 patterns. The clone A was also detected in all 5 environmental vanA-containing E. faecium isolates. Strains did not contain esp or hyl virulence genes. Multilocus sequence typing was performed in 4 E. faecium isolates representative of the 4 detected pulsotypes (A, A1, B, and C), and 2 different sequence types were identified (ST18 and ST80), both of them included in clonal complex CC17. These strains contained the IS16 element and showed ampicillin and ciprofloxacin resistance. VA resistance could be an emerging problem in Tunisia, and this is one of the first cases described so far in this country.

Highly drug-resistant Salmonella enterica serotype Kentucky ST198-X1: a microbiological study.

BACKGROUND: Salmonella enterica is a major global food-borne pathogen, causing life-threatening infections. Ciprofloxacin and extended-spectrum cephalosporins (ESCs) are the drugs of choice for severe infections. We previously reported a ciprofloxacin-resistant S. enterica serotype Kentucky (S Kentucky) ST198-X1 strain that emerged in Egypt and spread throughout Africa and the Middle East from 2002 to 2008. We aimed to monitor recent trends in the location of transmission and antimicrobial resistance of this strain. METHODS: We analysed isolates of S Kentucky collected by the French national surveillance system for salmonellosis in France from Jan 1, 2000, to Dec 31, 2011, and at two sites in Casablanca, Morocco, between Jan 1, 2003, and Dec 31, 2011. We analysed patterns of travel of patients infected with a ciprofloxacin-resistant strain of S Kentucky. We identified isolates showing resistance to ESCs or decreased susceptibility to carbapenems, characterised isolates by XbaI-pulsed field gel electrophoresis and multilocus sequence typing, and assessed mechanisms of bacterial resistance to antimicrobial drugs. FINDINGS: 954 (1%) of 128,836 serotyped Salmonella spp isolates in France were identified as S Kentucky, as were 30 (13%) of 226 Salmonella spp isolates from Morocco. During 2000-08, 200 (40%) of 497 subculturable isolates of S Kentucky obtained in France were resistant to ciprofloxacin, compared with 376 (83%) of 455 isolates in 2009-11, suggesting a recent increase in ciprofloxacin resistance in France. Travel histories suggested S Kentucky infections originated predominantly in east Africa, north Africa, west Africa, and the Middle East, but also arose in India. We report several occurrences of acquisition of extended-spectrum ß-lactamase (CTX-M-1, CTX-M-15), plasmid-encoded cephalosporinase (CMY-2), or carbapenemase (OXA-48, VIM-2) genes by ciprofloxacin-resistant isolates of S Kentucky ST198-X1 from the Mediterranean area since 2009. Many of these highly drug-resistant isolates were also resistant to most aminoglycosides, to co-trimoxazole (trimethoprim-sulfamethoxazole), and to azithromycin. INTERPRETATION: The potential risk to public health posed by ciprofloxacin-resistant S Kentucky ST198-X1 warrants its inclusion in national programmes for the control of S. enterica in food-producing animals, in particular in poultry. FUNDING: Institut Pasteur, Institut de Veille Sanitaire, Fondation pour la Recherche Médicale, French Government Investissement d'Avenir programme.

[Resistance in Gram negative bacteria: what is the current situation?]. / Résistance chez les bacilles Gram négatif : Où en sommes-nous ?

Emergence of antibiotic resistance put an end to the antibiotic miracle. According to recent review data, the number of cases of multiresistant bacteria, which are resistant to all antibiotics available, is increasing as well in the developed countries as in the developing countries. To face the emergence of these bacteria, it is necessary to evaluate the situation in Tunisian hospitals and act consequently. This review provide recent data on antibiotic resistance in Gram negative bacilli in Tunisian hospitals by focusing on some emergent resistances, which represent a daily challenge for the medical profession, such as extended spectrum beta-lactamases, carbapenem resistance, and fluoroquinolone resistance.

[The widening challenge of extended spectrum ß-lactamases]. / Les bêta-lactamases à spectre étendu : le défi s'accentue.

Since 1980, the prescription of new semi-synthetic molecules of third generation cephalosporins changed the course of modern medicine. However, the acquired resistance against these antibiotics was rapidly developed with the production of extended spectrum ß-lactamases (ESBL) (TEM and SHV types) disseminated mainly by nosocomial Klebsiella pneumoniae clones. Since around 2000, we are facing a watershed in ESBL epidemiology because of the widespread of the CTX-M enzymes among Escherichia coli isolates in community as well as in hospitals. The dissemination of these new ESBL in community within a commensal bacterium is a threat for the public health. The risk is to be in front of an uncontrollable resistance existing everywhere. It is the purpose of this review to focus, in particular, on the changing epidemiology and the spread of ESBL(s) and to provide updated data on definition, classification and laboratory detection of ESBL(s) that will help to control this resistance.

[Does the emergence of antibiotic resistance announce the return of the dark ages?]. / L'émergence de la résistance aux antibiotiques annonce-t-elle le retour des âges sombres ?

Antibiotic revolution changed the course of modern medicine, by decreasing mortality due to bacterial infections. However, bacteria have developed several ways of resistance against all antibiotics used. In view of the rise of resistance and of its dissemination to different bacterial families, new effective antibiotics are scare and the return in the pre-antibiotic era seems to be a reality for some parts of the world. This review revises the worrying phenomenon of antibiotic resistance focusing on some examples of "superbugs", which represent a daily challenge for the medical profession, such as methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, extended spectrum ß-lactamae-producing Enterobacteriaceae as well as carbapenem-resistant Pseudomonas aeruginosa. Facing the emergence of the multiresistant strains, the priority is obviously to control the spread of these microorganisms. It is only through the prudent use of antimicrobial drugs and the introduction of new and effective antibiotics that the antibiotic resistance will be slowed down and that we continue to treat bacterial infections.

[The changing epidemiology of extended spectrum ß-lactamase-producing Klebsiella pneumoniae]. / Changement de l'épidémiologie de Klebsiella pneumoniae productrice de ß-lactamases à spectre élargi.

In the last two decades, Klebsiella pneumoniae demonstrated some characteristics of acquisition of plasmids coding extended spectrum ß-lactamases (ESBL). The review data showed an increase in worldwide prevalence of ESBL and a temporal shift in the prevalence of ESBL types in K. pneumoniae during this last decade. CTX-M-15 seems to be the predominant ESBL type in K. pneumoniae in some parts of the world. The dissemination of several nosocomial CTX-M-15-producing K. pneumoniae clones was reported unlike the worldwide dissemination of a single virulent ST131 CTX-M-15 producing Escherichia coli clone. The diversity of plasmids carrying the bla(CTX-M-15) gene in K. pneumoniae suggested the frequent transfer of this gene between different replicons. The acquisition of the bla(CTX-M-15) gene by K. pneumoniae was probably occurred via horizontal transfer from E. coli.