[The Clumping factor B gene typing in discriminating the strains of nosocomial-acquired methicillin-resistant Staphylococcus aureus].

Abstract

To evaluate the clfB typing method in discriminating the ST239 methicillin-resistant Staphylococcus aureus (MRSA) isolated from patients under nosocomial infection in Tianjin first central hospital so as to access the clinical risk factors and outcomes of the MRSA nosocomial infection from ICU and non-ICU departments. Forty-two stains of MRSA with known SCCmec type were chosen in both ICU (n = 35) and non-ICU (n = 7) wards, from 2006 to 2012, of which MLST genotype was ST239. Clinical risk factors and rates on drug resistant to MRSA were counted, respectively. All the isolates of MRSA belonged to the same lineage 3 and 6 haplotypes, based on clfB variable-number tandom repeats typing. Thirty-five isolates from ICU belonged to 6 haplotypes, among which clfB3-52, 3-52E, 3-50, 3-52C, 3-50A and 3-50E were accouted for 42.9%, 37.1%, 8.6%, 5.7%, 2.9% and 2.9%, respectively. Seven isolates from non-ICU belonged to 3 haplotypes, in which 3-52, 3-52E and 3-50 were accouted for 42.8%, 28.6%, 28.6%, respectively. When clfB typing was combined with SCCmec typing in use, results showed that the index of discrimination as 0.767, better than clfB (ID = 0.688) or SCCmec (ID = 0.303) used alone. SCCmec III -clfB3-52E seemed as the major clone among the 10 haplotypes of clfB/SCCmec typing, which was accounted for 40.4% . There were significant differences on the length of hospitalization (P < 0.005) and the duration of antibiotics use (P < 0.05) between ICU and non-ICU. The clfB typing method which was based on variable-numbers of tandom repeats showed powerful ability of resolution. It could also be combined with MLST and SCCmec typing to be used in local epidemiological investigations.