Tracing the origin of an outbreak of methicillin-resistant Staphylococcus aureus infections in a Portuguese hospital by molecular fingerprinting methods.
Seventy-six methicillin-resistant Staphylococcus aureus (MRSA) isolates were collected from July 1992 to May 1995 at a 400-bed district hospital in the northeast of Portugal. During the second half of the surveillance period, in July of 1994, an outbreak was detected in the orthopedic ward. Thirty-three (out of the 76) MRSA strains were recovered only in this ward during the outbreak period. All strains were characterized by a variety of genomic fingerprints. Hybridization of ClaI and SmaI restriction digests with the mecA- and Tn554-specific DNA probes was used to identify polymorphism and determine chromosomal location of these determinants, and pulsed-field gel electrophoretic analysis of SmaI digests was used to determine chromosomal backgrounds. All strains recovered during the outbreak in the orthopedic ward were found to belong to a single clone that carried the mecA polymorph I, Tn554 type E in a macrorestriction background called H (clone I::E::H1), which was identified in 18 patients, and 5 health care personnel and from a fomite sample, and was traced to a single transfer patient admitted to the hospital at the beginning of the outbreak. The new clone I::E::H1 differed only in the macrorestriction profile from the MRSA clone previously dominant in this hospital, known as Iberian epidemic clone I::E::A, which has already been identified in several Spanish and Portuguese hospitals.
Sanches
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Unidade de Genética Molecular, Instituto de Tecnologia Química e Biológica da Universidade Nova de Lisboa (ITQB/UNL), Oeiras, Portugal.
Aires de Sousa
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Cleto
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de Campos
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de Lencastre
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D015139:Blotting, Southern; D003428:Cross Infection / Q000382:microbiology; D016172:DNA Fingerprinting; D015342:DNA Probes; D004269:DNA, Bacterial / Q000032:analysis; D004196:Disease Outbreaks; D005838:Genotype; D006801:Humans; D017053:Infection Control; D008712:Methicillin / Q000494:pharmacology; D016106:Methicillin Resistance; D008826:Microbial Sensitivity Tests; D009693:Nucleic Acid Hybridization; D010406:Penicillins / Q000494:pharmacology; D011174:Portugal / Q000453:epidemiology; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000235:genetics / Q000378:metabolism
D015342:DNA Probes; D004269:DNA, Bacterial; D010406:Penicillins; D008712:Methicillin