VARIANT SUBPOPULATIONS OF STAPHYLOCOCCUS-AUREUS AS CAUSE OF PERSISTENT AND RECURRENT INFECTIONS

While S. aureus small colony variants (SCVs) have been recognized in c linical materials for decades, only recently have these strains been l inked to persistent, resistant, and relapsing infections. The biochemi cal basis for this phenotype appears to be reduced electron transport, which leads to many changes in these organisms, including decreased a lpha-toxin production. Reduced alpha-toxin has been found to facilitat e bacterial survival within cultured endothelial cells. This SCV subpo pulation is more resistant to antibiotics, grows very slowly, and demo nstrates unusual colony morphology. Hence, these resistant strains can be easily overloaded in the clinical microbiology laboratory, and may be resistant to conventional antibiotic therapy. Clinicians should as k the laboratory to search for SCVs with relapsing and resistant S. au reus infections.