Intestinal carriage of methicillin-resistant Staphylococcus aureus in nasal MRSA carriers hospitalized in the neonatal intensive care unit (Epidemiologic Perspectives & Innovations)

Background: The current data regarding the correlation between the methicillin-resistant Staphylococcus aureus (MRSA) clones carried in the nasal cavity and digestive tract are inadequate. Methods: MRSA strains were isolated from both the feces and nasal swabs of 21 nasal-MRSA carriers ranging from 10 to 104 days of age treated at the neonatal intensive care units of two hospitals. The molecular epidemiological characteristics of the isolates were determined: multilocus sequence types, spa-types, staphylococcal cassette chromosome mec (SCCmec) types, carriage of four exotoxin genes, and genes contained in commercially available kit. Results: The feces of all nasal carriers contained MRSA at levels ranging from 4.0 x 102 to 2.8 x 108 colony forming units/g feces. The MRSA clones isolated from the feces and the nasal swabs of each patient were the same. Four MRSA clones, clonal complex (CC) 8-SCCmec IVl, CC8-SCCmec IVb, CC1-SCCmec IVa and CC5-SCCmec IIa were identified from 21 patients. All CC8-SCCmec IVl strains and one of three CC5-SCCmec IIa strains carried the toxic shock syndrome toxin gene. Conclusions: The feces of tested MRSA carriers contained the same MRSA clones as the nasal isolates in considerable amounts, suggesting that more careful attention should be paid for the handling of excrement in the case of newborn babies or infants than that of adults.