Awareness of the virulence of coagulase-negative Staphylococci, previously regarded as saprophytes with minimal pathogenicity, has steadily increased. Eighty-seven individual patients diagnosed with acute osteomyelitis, as confirmed by microbiologic and pathologic analysis, were included in this study. Of these patients, 82% (71/87) were known to have diabetes mellitus. The prevalence of coagulase negative Staphylococcus was 40% (35/87) in deep bone cultures, 63% (22/35) of which were methicillin resistant. When the coagulase negative Staphylococcus group was assessed for prior long-term (>2 week) oral antibiotic treatment with ciprofloxacin, it was found that 54% (12/22) of the methicillin-resistant coagulase-negative Staphylococcal infected patients had received such treatment, compared with 15% (2/13) of patients with methicillin-sensitive coagulase-negative Staphylococcal osteomyelitis (p < 0.034). When the group was analyzed for prior long-term antibiotic treatment with amoxicillin/ clavulanate, 23% (5/22) of the methicillin-resistant patients had received oral amoxicillin/clavulanate, compared with 23% (3/13) of patients with methicillin-sensitive coagulase-negative Staphylococcal osteomyelitis (p > 0.05). Prevalence of polymicrobial infections, which constituted 29% (25/87) of all individual patients, was also analyzed. Of those patients with coagulase-negative isolates, 29% (10/35) were polymicrobial (p > 0.05). The results from this study suggest that infections of bone caused by coagulase-negative Staphylococci are associated with a high prevalence of methicillin resistance. This study also raises the question of whether injudicious prolonged use of ciprofloxacin may, in fact, promote proliferation of resistant organism strains.
ASJC Scopus subject areas
- Orthopedics and Sports Medicine