Epidemiological Study of Staphylococcal Colonization and Cross-Infection in Two West African Hospitals

Surveillance in two medium-size (250-300 beds) hospitals located in the most populated islands of Cape Verde was undertaken in July 1997 in order to obtain data concerning nasal carriage of staphylococci. Nasal swabs (172) taken from inpatients and health care workers (HCW) from different internment services yielded 68 Staphylococcus aureus and 105 coagulase-negative staphylococcal (CNS) isolates, demonstrating extensive colonization of both inpatients and HCW by S. aureus (carriage rate 41%) and CNS (carriage rate 65%). The most frequent CNS species were S. epidermidis and S. haemolyticus . Three species - S. aureus , S. epidermidis , and S. sciuri - were recovered from wound swabs. The antibiotic susceptibility profiles of S. aureus and CNS differed sharply: all 68 S. aureus were resistant to penicillin but were fully susceptible to oxacillin as well as the other antimicrobial agents tested - gentamicin; erythromycin, except for three strains; ciprofloxacin; sulfamethoxazole-trimethoprim, except for two strains; vancomycin; and amoxicillin/clavulanate. In contrast, most (91/105) of CNS were resistant to both penicillin and oxacillin, and a variable but substantial proportion of CNS isolates also carried multiresistant traits to gentamicin, erythromycin, sulfamethoxazole-trimethoprim, and amoxicillin/clavulanate. The analysis by PFGE of the methicillin-susceptible S. aureus (MSSA) and the methicillin-resistant S. epidermidis (MRSE) strains provided evidence for extensive cross-infection and cross-colonization from HCW to patients.