A prospective microbiological surveillance (PMS) program was developed in a comprehensive hospital-wide effort for control of nosocomial methicillin-resistant Staphylococcus aureus (MRSA). This PMS program entailed: 1) active identification of colonized and infected patients; 2) application of a screening microbiologic system for MRSA; 3) isolation of colonized and infected patients; 4) antibiotic decolonization of MRSA; and 5) educational efforts. The PMS program was studied over three and one half years for its contribution to infection control of MRSA, early identification of nosocomial MRSA outbreaks, use of the highest yield surveillance culture sites, and cost effectiveness. Following initiation of the PMS program in December 1982, during an MRSA outbreak, the frequency of new MRSA cases declined from 14 to none by the end of a 3-month pilot study. The frequency of new MRSA cases stabilized at approximately 2 per month until October 1983, when the PMS system allowed prompt detection of a new outbreak of 11 cases. Following isolation and antibiotic decolonization, the frequency of cases again declined to 3 per month. A third outbreak in December 1985 again was promptly detected and controlled. Infection to colonization ratio decreased from a maximum of 1.5 during outbreaks to a minimum of 0.17 after outbreaks. Wounds and tracheostomy sites provided the greatest yield of detection of new cases of MRSA. During one 15-month period, 35 of the 43 new cases were detected initially at wounds and tracheostomy sites. No new MRSA cases were detected by a positive axillary or nares site alone. The estimated quarterly cost of outbreaks and infection paralleled the quarterly frequency of new MRSA cases. The cost of managing MRSA outbreaks and treating MRSA infections versus the cost of implementing the PMS program suggested that the PMS program may be cost effective. This prospective microbiological surveillance program may be applicable to other institutions for hospital-wide infection control of MRSA.

A methicillin- and rifampin-resistant strain of Staphylococcus aureus was introduced into a university hospital by interstate transfer of an infected surgical patient. An outbreak occurred, and 17 patients became infected or colonized with the epidemic strain. Reservoirs appeared to be patients who were infected or colonized with the resistant S aureus and possibly two nurses who were nasal carriers. The outbreak isolate was likely spread by contact with contaminated hands of personnel. A retrospective case-control study identified tracheostomy, debridement, and irrigation of wounds by power spray and prolonged nasogastric intubation as risk factors for acquisition of the epidemic strain. Analysis of factors by groups indicated that surgical procedures, wound care procedures and instrumentation of the respiratory tract were significantly associated with cases. The nasal carrier state was eradicated in two nurses by topical application of 5% vancomycin. The epidemic strain was eradicated from the hospital 8 months after it was introduced.

A prospective four-year study on the infection rate of clean operative wounds is presented. From January 1982 to June 1985, a nurse epidemiologist and a medical team assessed 4,468 operative procedures, from the day of surgery to the patients' discharge from the hospital. The infection rate was 3.2%. A higher incidence of wound infection was detected in patients requiring emergency operations (5.1%), in drained wounds (5.4%), and in patients with conditions thought to predispose to infection, such as advanced cancer, hepatic cirrhosis, diabetes, nephrotic syndrome, previous splenectomy, and treatment with immunosuppressive drugs (7.8%). Age over 65 did not influence infection rates. There were up to tenfold differences in infection indices between surgeons performing the same clean procedures. The continued monitoring of clean wound infection rates allowed the early detection and control of infection outbreaks. Providing periodic information on infection rates to the different surgical services was associated with decreasing infection rates over time.