[Impact of control measures on the course of an outbreak of methicillin-resistant Staphylococcus aureus].
BACKGROUND
Outbreaks of nosocomial infection by methicillin resistent Staphylococcus aureus (MRSA) are a problem in many hospitals with the control measures to be adopted being controversial. An outbreak of MRSA in a 550-bed university hospital is herein described and the impact of the adopted control measures on the evolution of the epidemic in the general hospitalization area (GHA) was analyzed.


METHODS
The adopted control measures in the GHA were: microbiologic surveillance, cutaneous isolation measures, treatment of nasal carrier, and the early discharge of the cases. Hand washing was reinforced and a study of carriers was carried out on detection of sporadic cases (not related to the ICU). A molecular study of 70 strains of MRSA was performed with analysis of total plasmids, plasmid restriction pattern and chromosomic DNA analysis by pulsed field gel electrophoresis (PFGE).


RESULTS
From December 1990 to December 1993, 273 cases of MRSA were reported. One hundred seventy-two cases originated in the ICU and 101 cases in the GHA (sporadic cases). The incidence of MRSA in 1991-1993 was 13.6, 14.3, and 6.6% in the ICU and 0.17, 0.36, and 0.15% in the GHA, respectively. Molecular study of MRSA isolates (1991 and 1992) demonstrated two plasmid and two chromosomic patterns. The latter had a similarity coefficient > 0.90, probably belonging to the same "clone".


CONCLUSIONS
Despite the control measures adopted in the GHA the outbreak of MRSA originated in the ICU thereafter extending to the GHA. The rates of colonization detected, however, remained stable during the 3 years studied. On the other hand, the observation of a single "clone", responsible for the epidemic, suggest that most of the sporadic cases were autoctonous and due to failure in fulfillment of the established norms.
Sopena
N
N
Unidad de Enfermedades Infecciosas, Hospital Universitario Germans Trias i Pujol, Badalona.
Sabrià
M
M
Pedro-Botet
M L
ML
Giménez
M
M
Esteve
M
M
Caraballo
M
M
Mesalles
E
E
D003428:Cross Infection / Q000188:drug therapy / Q000453:epidemiology* / Q000517:prevention & control; D004196:Disease Outbreaks; D006801:Humans; D016106:Methicillin Resistance; D011815:R Factors / Q000032:analysis; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000517:prevention & control; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics