Contrôle des épidémies de S. aureus résistant à la méticilline : analyse critique des stratégies préconisées

[Impact of nasal colonization by methicillin-resistant Staphylococcus aureus among geriatric intermediate care facility patients]

OBJECTIVE

To evaluate the impact of nasal carriage of Methicillin Resistant Staphylococcus aureus (MRSA) on antibiotic cost, infection morbidity, mortality and length of stay in a geriatric population.

METHODS

341 consecutive elderly patients (mean age 83.4 +/- 8.7 years) admitted to an intermediate care facility were prospectively include between November 1998 and October 1999. Nasal swab cultures were taken on admission.

RESULTS

In sixty patients (17.6%) no nasal swab was taken. Among the 281 patients screened, 52 were identified as MRSA carriers. The principle predictive factors were: diabetes (p=0,046), sores (p=0,03), malnutrition (p=0,02), polypathology (p=0,02) and prolongation of previous hospitalisation (p=0,09).

CONCLUSION

Nasal carriage of MRSA on admission to the facility was not a deleterious prognostic factor regarding duration of stay, infectious morbidity and antibiotic cost, but was associated with higher mortality risk.

La méticillino-résistance de Staphylococcus aureus isolés à Abidjan (1998–2001) : un nouveau problème en milieu hospitalier

OBJECTIVE

The authors had for aim to determine the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) strains on infections in Abidjan as well as their susceptibility to other antibiotics.

METHODS

Three hundred and forty strains of S. aureus from various samples of hospitalized patients were studied. Methicillin-resistance was assessed using oxacillin disk diffusion in agar. The MRSA, once detected, were confirmed by screening in Mueller-Hinton agar containing oxacillin at 6 microg/ml. The susceptibility to other antibiotics was analyzed using an antibiogram in agar medium.

RESULTS

Twenty-five percent of strains were resistant to methicillin (MRSA strains). Those MRSA were identified mainly in blood culture (14.2%), pus (4%) and urine (1.9%). Samples were collected in neonatal unit (13%), surgical units (5.4%) and intensive care unit (3.4%). A variable proportion of MRSA expressed resistance to other families of antibiotics: aminoglycosides 77.6%, rifampicin 8.8%, fluoroquinolones 34.1% and vancomycin 5.9%.

CONCLUSION

Circulation of multidrug resistant MRSA in hospital, especially in neonatal unit, should lead to surveillance. Risk factors and other associated markers need to be identified.

[Antibiotic resistance of Staphylococcus aureus at north Lebanon: place of the methicillin resistance and comparison of detection methods]

The aim of this study was to evaluate the susceptibility of 100 Staphylococcus aureus strains isolated from the laboratory of Microbiology of the Islami Hospital of Tripoli (Lebanon) to 19 antibiotics, and to determine the prevalence of methicillin resistant strains. 30% of strains studied were methicillin resistant, 96% were resistant to the penicillin G. Clavulanic acid restaurated the amoxicillin activity to 29%. The resistance level was 34% for amikacin, 3% for gentamycin and tobramycin, 10% for chloramphenicol, 44.33% for tetracyclin, 7% for erythromycin, 4.04% for clindamycin, 20% for trimethoprim-sulfametoxasol and 0% for vancomycin and teicoplanin. The methicillin-resistant Staphylococcus aureus possess more important resistant level in comparison with the methicillin sensitive strains. We compared the ability of latex agglutination test (Slidex(R) SARM, bioMérieux, France) to detect the production of penicillin-binding protein 2' (PBP 2') in 100 clinical isolates of S. aureus with two reference methods: the oxacillin disk diffusion test and the MIC determination by the E-test (AB BIODISK, Sweden). The two reference methods give the same results for the detection of methicillin resistant S. aureus. The Slidex test was positive for all 30 isolates determined to be methicillin resistant by the reference methods (sensitivity 100%). The latex test was negative for 42 of 70 isolates determined to be methicillin susceptible by the reference methods, and the latex test was positive for 28 isolates determined to be susceptible (specificity 60%).

[Study of methicillin-resistant Staphylococcus aureus colonization among intermediate-care facility patients]

PURPOSE

Prevalence of methicillin-resistant Staphylococcus aureus is high in the Poitiers teaching hospital, particularly in the intermediate care facilities. We performed a survey of methicillin-resistant Staphylococcus aureus colonization in the intermediate care facilities and 265 patients were included.

METHODS

Nasal, cutaneous and wound swab cultures were done at the time of admission and at the time of the patients' departure. A decolonization procedure of methicillin-resistant Staphylococcus aureus carriers was performed using nasal application of fusidic acid and different soaps for the skin. At entry, 17.7% of patients were methicillin-resistant Staphylococcus aureus carriers (of at least one location). At departure, 30.4% were methicillin-resistant Staphylococcus aureus carriers. Among methicillin-resistant Staphylococcus aureus non-carriers at entry, 24.3% became methicillin-resistant Staphylococcus aureus carriers.

RESULTS

The principal risk factor of carriage was the initial presence of a wound (RR = 3.6). The incidence rate of methicillin-resistant Staphylococcus aureus infection among the 265 patients included was 3%.

CONCLUSION

The systematic screening of patients at the time of admission is expensive and isolation technically hard to manage in the intermediate care facilities. The risk factor we found in this study allow us to propose a 'light' screening limited to patients with wounds.