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With the aid of epidemiologic tools such as serotyping and bacteriocin typing, organisms involved in hospital-acquired infections were traced to their hospital reservoir. One of these reservoirs was an instrument used to measure specific gravity of urine, the urometer.

A rapid method for the identification of lipids characteristic of the genera Corynebacterium, Mycobacterium, Nocardia, and the "rhodochrous group" has been developed. Modifications of previously described methods make this procedure suitable for use in the clinical laboratory. Thin-layer chromatography is used to demonstrate the presence of the lipid characteristic of Nocardia spp. (type A) in some corynebacteria, nocardias, and members of the "rhodochrous group." Precipitation in ether and ethanol is used to demonstrate the presence of mycobacterial mycolic acids. Since this procedure can be carried out in less than 2 days and the lipids are extracted from the same batch of cells grown for diaminopimelic acid and whole-cell sugar analyses, it can readily be added to the battery of tests performed in reference laboratories that deal with aerobic actinomycetes and related bacteria.

Blood isolates from 13 patients in one hospital were positive for Klebsiella pneumoniae over a two-week period. Vials of potassium chloride used in intravenous fluid admixture initially were suspected of being contaminated and thus causing the problem. However, a comparison of patients who had blood cultures positive for K. pneumoniae with control patients who had blood cultures negative for this organism during the same period identified no common features that would explain the increase in K. pneumoniae blood isolates. Careful evaluation of laboratory data suggested that six of the 13 culture-positive patients had probable pseudobacteremia, an explanation that would account for the increase in isolates above the endemic level of true K. pneumoniae bacteremia in the hospital. Epidemiologic data suggested that cross-contamination of adjacent and non-adjacent blood culture vials on the radiometric blood culture analyzer was the cause of pseudobacteremia; K. pneumoniae serotyping data supported this hypothesis. A mock trial using the analyzer demonstrated that cross-contamination of non-adjacent vials by the sampling needles could occur. Changing the sampling needles of the analyzer daily, in accordance with the manufacturer's recommendations, prevented further episodes of pseudobacteremia from the analyzer.

During a 3 1/2-year period (January 1978 through June 1981), 245 patients in a university hospital became colonized or infected with methicillin-resistant Staphylococcus aureus. During the first 18 months, the incidence of colonization and infection was only 0.05%. After a focal outbreak of methicillin-resistant S aureus in the burn unit, acquisition of the organism by patients on other wards increased significantly. Nonburn patients acquired the organism more often during time periods when newly admitted burn patients acquired methicillin-resistant S aureus. After the burn unit was closed, acquisition of the organism among nonburn patients on adult surgical and medical services decreased significantly. A questionnaire survey of other institutions disclosed that large outbreaks of this infection occurred more frequently in hospitals with burn units. These studies suggest that the occurrence of methicillin-resistant S aureus infections in burn units may lead to increased transmission of the organism to nonburn patients and that control of the infection in such units may reduce spread of the organism to patients without burns.

Acute pyogenic infections of the skin, caused by hemolytic streptococci and S. aureus, account for the vast majority of bacterial infections of the skin seen in ambulatory practice. In preschool children the principal manifestation is pyoderma, which is usually caused by Group A Streptococcus. In this age group pyoderma regularly responds to systemic penicillin therapy plus adjunctive local care to the lesions. However, in older age groups, the ability to distinguish streptococcal from staphylococcal skin infections on the basis of clinical features alone is poor, and penicillin treatment failures are more common. Safe, effective antibiotics that are effective against both staphylococci and streptococci are readily available. For this reason penicillinase-resistant semisynthtic penicillins and or erythromycin can be used to treat acute pyogenic skin infections in older age groups.

Although several outbreaks of methicillin-resistant Staphylococcus aureus (MRSA) infections have been reported in recent years, the geographic distribution and frequency of MRSA infections in American hospitals is unknown. We conducted a questionnaire survey to determine the magnitude of the problem. Data from 261 hospitals were included in the survey. MRSA were reported by 145 hospitals located in 36 states. Large hospitals reported these organisms significantly more often than small hospitals (p less than .001). University hospitals reported MRSA more often than community or community-teaching hospitals (p less than .001 and p less than .005, respectively). The number of hospitals reporting MRSA increased from 24 in 1975 to 112 in 1980 (p less than .001. Our data suggest that MRSA are widely distributed geographically and that the number of hospitals with these organisms has increased dramatically since 1975.

Thirteen isolates of Nocardia caviae from 12 different clinical sources were received and identified over a 5(1/2)-year period by the Mycology Division of the Center for Disease Control. The results of morphological, biochemical, and physiological studies on these isolates were compared with those obtained with four reference cultures of N. caviae received from the Institute of Microbiology, Rutgers University. Comparison showed that N. caviae isolates form a homogeneous group that is usually easily distinguished from N. asteroides, N. brasiliensis, and other pathogenic aerobic actinomycetes. The clinical sources included nine human and two animal infections and one human isolate apparently not associated with disease. Previous reports of N. caviae infections in man have been limited to rare cases of actinomycotic mycetoma. Among the human infections reported in this series are one case of mycetoma, one case of "mycotic" keratitis, one case of skin abscess, two cases of osteomyelitis, and four cases of serious pulmonary infection caused by N. caviae.