[Panton-Valentine leukocidin-positive osteoarticular infections]. / Infections ostéoarticulaires à Staphylococcus aureus portant le gène de la leucocidine de Panton-Valentine.

OBJECTIVES: The aim of our study was to evaluate the frequency of osteoarticular infections with Panton-Valentine leukocidin-positive (PVL) Staphylococcus aureus (PVL-SA) among patients admitted to the orthopedic ward at the Sahloul University Hospital (Sousse, Tunisia) and to study the characteristics of these strains and patients. MATERIALS AND METHODS: We conducted a retrospective descriptive study over a 5-year period. Bacterial identification, antibiotic susceptibility, and molecular study (PCR to detect of the luk-PV gene that encodes PVL) were performed for 44 S. aureus isolates. RESULTS: Panton-Valentine toxin was found in 41% of S. aureus cases, mainly males, and 39% of the PVL(+) cases were methicillin-sensitive (MSSA). These strains constitute a reservoir of PVL genes that can lead to the emergence and spread of PVL-SA clones resistant to methicillin (MRSA). In our series, PVL-MRSA accounted for 9% of all S. aureus isolates. Their profile and antibiotic resistance is that of clone ST80, frequently isolated in Europe and also reported in Algeria and Tunisia. CONCLUSION: It is desirable to test for PVL routinely in the laboratory to implement appropriate treatment and to monitor the epidemiology of these PVL-SA strains actively. Further measures should be undertaken to prevent and fight infections by these strains.

Prevalence of plasmid-mediated quinolone resistance determinants in Enterobacteriaceae from Tunisia.

The spread of plasmid-mediated quinolone resistance determinants (qnr-like determinants, aac(6')-Ib-cr and qepA genes) was evaluated in a collection of 281 nalidixic acid-resistant enterobacterial isolates recovered between September 2005 and December 2007 at the Sahloul Hospital, Sousse, Tunisia. Sixteen percent of those isolates carried qnr genes encoding the QnrB1, QnrB2, QnrA6 or QnrS1 determinants. Most qnr-positive isolates were extended-spectrum ß-lactamase (ESBL) producers, being predominantly of the CTX-M-15 type, but also of the SHV-28 and SHV-12 types. The qnr genes were located on plasmids with a size in the range 55-150 kb. The qnrB2 gene was associated with sul1-type integron structures and the qnrB1 gene was associated with orf1005, whereas the genetic environment of qnrA6 was unknown. In two isolates, the qnrS1 gene was located downstream of an ISEcl2 element on plasmids that often carried the narrow-spectrum ß-lactamase gene bla(LAP-2); qepA and aac(6')-Ib-cr were not detected. The present study highlights the wide spread of Qnr-like determinants in Tunisia, with an association with the ESBL CTX-M-15 in human clinical isolates.

[Characterization of the resistance mechanism to beta-lactams in Acinetobacter baumannii strains isolated in the university hospital Sahloul in Tunisia (2005)]. / Caractérisation des mécanismes enzymatiques de résistance aux beta-lactamines chez des souches de Acinetobacter baumannii isolées à l'hôpital universitaire Sahloul, Sousse en Tunisie (2005).

OBJECTIVE: The bacterial multiresistance to beta-lactams and imipenem is an emergent feature in the university hospital Sahloul in Tunisia. This study was conducted to elucidate natural and acquired mechanism of resistance to beta-lactams in strains of Acinetobacter baumannii isolated in different wards of the hospital. MATERIALS AND METHODS: A specimen of 26 clinical strains of Acinetobacter baumannii was studied. beta-lactamases characterization was done by isoelectric focusing on gel of crude enzymatic extract, phenotypic tests for detection of extended spectrum beta-lactamases (ESBL) and metallo-beta-lactamases (MBL) and finally by amplification (PCR) and sequencing of genes encoding naturally occurring AmpC, the insertion sequence ISAbaI and oxacillinase with carbapenemase activity. Study of clonality of strains was performed by analysis of genomic DNA digested by the restriction enzyme ApaI and separated by pulsed field gel electrophoresis (PFGE). RESULTS: The isoelectric focusing on gel revealed two bands of beta-lactamase activity with a pI upper than 8. None ESBL or MBL was detected. PCR for AmpC, ISAbaI and OXA-69 were positive for all studied strains. The sequencing of PCR products show high identity (99-100%) with genes described previously. PFGE analysis has demonstrated clonality of studied strains. CONCLUSION: Resistance to beta-lactams including imipenem is associated to the hyper production of the AmpC enzyme and expression of OXA-69. Those enzymatic mechanisms are associated with the natural low permeability to beta-lactams which characterize Acinetobacter baumannii strains. High clonal relationship of studied strains proved by PFGE analysis has shown the necessity of implementation of strict hygienic rules and rational antibiotic usage.

[Clinical and epidemiological characterization of infections due to imipenem resistant Acinetobacter baumannii at the university hospital Sahloul, Tunisia]. / Caractérisation clinico-épidémiologique des infections à Acinetobacter baumannii résistant à l'imipénème au CHU Sahloul, Tunisie.

OBJECTIVE: to characterize epidemiological and clinical features related to the multi-drug Acinetobacter baumannii infections in the university hospital Sahloul in Tunisia. MATERIAL AND METHODS: retrospective study including twenty-four imipenem resistant Acinetobacter baumannii isolated from twenty patients hospitalized in different wards of the hospital. Study of clinical features related to the infection by multi-drug Acinetobacter baumannii, bacterial identification by classical identification scheme, antibiotic susceptibilities were determined by the disk diffusion method; genotyping was performed by arbitrarily-primed PCR. RESULTS: the most incriminated ward was the intensive care unit with a high prevalence of septicaemia. All studied strains were multi-drug to all beta-lactams tested. Genotyping has shown the clonality of studied strains. Features incriminated in the acquisition of infection were essentially immunodeficiency, invasive manoeuvring and antibiotherapy. CONCLUSION: multidrug Acinetobacter baumannii is increasingly isolated in our hospital. Rational use of antibiotics and rigorous application of hygienic rules could contribute to limit dissemination of such strains.

[Antibiotics resistance of meticilline-resistant Staphylococcus aureus: detection of the first glycopeptides low sensibility strains in Tunisia]. / Résistance aux antibiotiques de Staphylococcus aureus résistant à la méticilline: détection des premières souches de sensibilité diminuée aux glycopeptides en Tunisie.

The adaptation of Staphylococcus aureus to the hospital environment led to the acquisition of resistance to all antibiotics available in clinical practice. The aim of this study was to investigate the methicillin-resistant Staphylococcus aureus (MRSA) strains isolated in the F. Bourguiba hospital of Monastir (Tunisia). We determined the antibiotype of all Staphylococcus aureus strains identified. Susceptibility rates to fosfomycin, chloramphenicol, rifampicin and pristinamycin were 7%, 3%, 2% and 0%, respectively. The prevalence of MRSA was 15.5% (96 strains); their susceptible to gentamicin progressively increased. The minimum inhibitory concentration (MICs) of oxacillin, vancomycin and teicoplanin were evaluated for the 96 MRSA strains. We identified two MRSA strains (M4 and M41) showing reduced glycopeptides susceptibility. Further analysis revealed that M4 and M41 harbor the gene encoding the class S and class F proteins specific for the Panton-Valentine Leukocidin (PVL). The mecA gene was detected only in strain M41 which harbors the Staphylococcal Cassette Chromosome (SCCmec) type III. This is the first reported MRSA showing reduced susceptibility to glycopeptides in Tunisia. Regulatory surveillance of susceptibility to antibiotics is needed to reduce the morbidity and the mortality rates as well as societal costs of S. aureus infections.

[Epidemiologic markers in Haemophilus influenzae]. / Les marqueurs épidémiologiques chez Haemophilus influenzae.

Twenty-six strains of Haemophilus influenzae, isolated from diverse pathological products in two different hospitals in the center of Tunisia (Sousse-Monastir) have been compared with two different genotypic techniques: AP-PCR and pulsed-field gel electrophoresis. These two techniques showed a high discriminating power. The combination of the results of both techniques were complementary and have individualized twenty-five heterogeneous patterns among the twenty-six strains. Among the strains of respiratory origin, only two were identical, they have been isolated from two patients hospitalized in the same period and the same hospital. Excepted the two above mentioned cases, this study showed a high genetical heterogeneity of the strains.

[Contribution of phage typing and ribotyping in investigating a typhoid fever outbreak in Tunisia]. / Apport de la lysotypie et de la ribotypie dans l'investigation d'une epidémie de fièvre typhoïde en Tunisie.

A study was carried out to investigate an outbreak of typhoid fever that occurred in Sousse city and in the vicinity of Sousse (Tunisia) during summer 1999. Twenty four isolates of Salmonella enterica serotype Typhi were isolated in hospitalized patients with a typhoid fever in two hospitals (Farhat Hached Sousse and M'saken) and were studied with the help of two molecular typing methods: phage typing and automated ribotyping. Twenty one isolates with the Vi antigen had profile DVS (Degraded Vi Strain), one isolate with the Vi antigen belonged to phage type A and two isolates were non phage typable (no Vi antigen). The same ribotype was found in 22 out of 24 isolates. The results suggested that ribotyping is more discriminative than phage typing in this case in distinguishing strains and the strains shared the same source of the contamination. Unfortunately the precise source of the contamination could not be determined.

Outbreak of Pseudomonas putida bacteraemia in a neonatal intensive care unit.

During the period of 9-27 March 2001, Pseudomonas putida strains were recovered from 10 neonates hospitalized in the neonatal intensive care unit of Farhat Hached Hospital, Sousse (Tunisia). Seven neonates developed bacteraemia, and three had an umbilical catheter-related infection (without bacteraemia). A total of 18 isolates were cultured from blood (N = 11) and catheters (N = 7). These isolates were identified as P. putida by routine biochemical methods (API 20 NE, bioMérieux, Lyon, France). Restriction endonuclease DNA profiles were determined by pulsed-field gel electrophoresis using two endonucleases XbaI and SpeI. They yielded the same patterns showing that the outbreak was caused by a single clone of P. putida. Although the antiseptic solutions used to clean the umbilicus were implicated circumstantially as probable sources, they were not sampled and so this could not be confirmed.

Group A streptococci in children with acute pharyngitis in Sousse, Tunisia.

A 1-year prospective study in 2 paediatric outpatient clinics in Sousse, Tunisia, aimed to determine the presence of group A streptococci in acute pharyngitis cases and carriers, and the distribution of the serotypes and biotypes. Group A streptococci were found in 9.0% of throat swabs from 155 controls and 17.7% from 474 patients (P < 0.05). Of 43 strains isolated from patients and submitted for typing, 15 different types were identified, the most common being M75 (14 strains; 32.5%), M9 (6 strains; 14.0%), M76 (5 strains; 11.6%) and M12 (4 strains; 9.3%). Three strains were non-typeable (7.0%). Biotyping of the strains showed 3 predominant biotypes: biotype 3 (n = 14), biotype 2 (n = 11), and biotype 1 (n = 7).

Group A streptococci in children with acute pharyngitis in Sousse, Tunisia

A 1-year prospective study in 2 paediatric outpatient clinics in Sousse, Tunisia, aimed to determine the presence of group A streptococci in acute pharyngitis cases and carriers, and the distribution of the serotypes and biotypes. Group A streptococci were found in 9.0% of throat swabs from 155 controls and 17.7% from 474 patients [P < 0.05]. Of 43 strains isolated from patients and submitted for typing, 15 different types were identified, the most common being M75 [14 strains; 32.5%], M9 [6 strains; 14.0%], M76 [5 strains; 11.6%] and M12 [4 strains; 9.3%]. Three strains were non-typeable [7.0%]. Biotyping of the strains showed 3 predominant biotypes: biotype 3 [n = 14], biotype 2 [n = 11], and biotype 1 [n = 7]