Endemicity of Multiple Staphylococcal Phage Types: Relation to Two Common Source Outbreaks

Abstract

An outbreak of Staphylococcus aureus bacteremia occurred among patients treated in the hemodialysis unit in 1971. A second outbreak of S. aureus peritonitis occurred in 1973 in patients with chronic indwelling peritoneal catheters cared for together in the medial intensive care unit. Although the attending personnel, patients, and geographical locations were different in each outbreak, the following similarities were noted: (1) more than one phage type was epidemic; (2) an exogenous mode of spread with cross-contamination between personnel and patient as well as between patient and patient, and (3) breaks in sterile technique when handling the arteriovenous shunt site or the peritoneal catheter were made without the staff conducting the procedure being aware of their occurrence. Culture surveys done during nonepidemic periods demonstrated persistence of several of the same phage types found during the two epidemics. Thus, an endemic reservoir of several different staphylococcal phage types was present. Careful, consistent application of aseptic technique when handling either arteriovenous shunts or peritoneal catheters and hand washing in between patients was required to prevent the endemic strains from becoming epidemic.