Methicillin-resistant Staphylococcus aureus (MRSA) isolated at Fukuoka University Hospital and hospitals and clinics in the Fukuoka city area.

Bacteriological and epidemiological studies were carried out on 106 isolates of methicillin-resistant Staphylococcus aureus (MRSA) isolated at our hospital (56 isolates) and from 15 other hospitals and clinics (50 isolates) in the Fukuoka city area. Strains were studied regarding coagulase-type, beta-lactamase production, and antimicrobial susceptibility; genotype studies used pulsed-field gel electrophoresis (PFGE) with cluster analysis. The majority of isolates produced coagulase type II (75.5%) and beta-lactamase (72. 6%); there was high susceptibility to arbekacin (84.9%) but no resistance to vancomycin. Dendrogram analysis of PFGE patterns identified five major clusters that generally correlated with coagulase-type and beta-lactamase production. Though isolates of two clusters were both coagulase type II and beta-lactamase producing, which was the most common circulating strain both in our hospital and other hospitals and clinics, dendrogram analysis of PFGE patterns showed that they were heterogeneous. Four genetically identical isolates from the same hospital suggested the existence of hospital-specific strains. Nine genetically identical isolates from intensive care units (ICU) in our hospital suggested that a unique strain of MRSA was found there. It had not been transmitted from another area. PFGE with cluster analysis seemed to be an essential tool to detect area-specific or hospital-specific strains undifferentiated by phenotyping. These findings confirmed that a combination of PFGE, including cluster analysis along with coagulase-type and beta-lactamase production may provide more detailed information for the epidemiological study of MRSA.

Epidemiological study of methicillin-resistant Staphylococcus aureus at Fukuoka University Hospital.

To clarify what types of methicillin-resistant Staphylococcus aureus (MRSA) strains were easily transmitted and colonized in the inpatients of the emergency center and the neonatal intensive-care unit (NICU) at Fukuoka University Hospital, 70 MRSA isolates obtained from February to November 1995 (the first survey) and from November 1996 to March 1997 (the second survey) were investigated biologically and genetically. Pulsed-field gel electrophoresis (PFGE) showed 12 types (PFGE types A-L) of DNA patterns for the MRSA isolates. At the emergency center, the PFGE types A and B strains were isolated from 40.9% and 27.2% of the MRSA-excreting patients in the first survey, respectively, while type E was isolated from 66.7% in the second survey. At the NICU, type A and J strains were isolated from 33.3% and 55.6% of the MRSA-excreting patients in the first survey, while the types A and B were isolated from 25% and 50%, respectively, in the second survey. Type A-D strains were isolated in both wards, while other epidemic types strains were isolated in only one ward. These results suggest that the type A and B strains have been colonized in the two wards for a long time and these strains might spread and colonize easily in the patients. Type C and D strains have also been colonized, but only in a small population over the two wards.

Mutagenic activity of acrinol in Salmonella typhimurium.

Acrinol, which is used as a disinfectant and an abortifacient in several countries, was tested for mutagenicity by the Ames test system. After incubation with a rat-liver S9 microsomal preparation, acrinol showed potent mutagenicity for Salmonella typhimurium strains TA98 and TA100, although it had no direct mutagenicity for the microorganisms.

Pili mediated agglutination of Serratia marcescens in human urine.

Of 51 strains of Serratia marcescens isolated from patients with urinary or respiratory tract infections, 35 agglutinated in human urine. The agglutinating strains possessed numerous pili which were morphologically distinct from common pili or type I pili. The diameter of the pili was 3 nm and the average length was 0.3 micrometer. Electron microscopic examination showed that 80% or more of the cells of the agglutinating strains and 0 to 8% of the cells of the nonagglutinating strains were piliated. When an agglutinating strain was heated at 55 C for 10 min, it lost its agglutinating capacity and concomitantly its pili. These results suggest that the agglutination might occur because of interactions between the pili and some factors in human urine. The urinary slime appears to contain these agglutinating factors.

Interaction of the lamB protein with the peptidoglycan layer in Escherichia coli K12.

In Escherichia coli K12 the product of gene lamB is an outer membrane protein involved in the transport of maltose and maltodextrins and serving as a receptor for several bacteriophages including lambda. About 30 to 40% of this protein can be recovered associated to peptidoglycan when the cells are dissolved in sodium dodecyl sulfate in the presence of 2 mM Mg2+ ions. The bound protein can then be quantitatively eluted from peptidoglycan by incubating the complex in Triton X-100 and EDTA, or sodium dodecyl sulfate and NaCl. The protein eluted in such ways is still totally active in its phage-neutralizing activity. Two other membrane proteins known to behave similarly to the lamB protein are proteins Ia and Ib. However the binding of these proteins to peptidoglycan appears tighter, in several respects, than that of the lamB protein. The lamB protein may span the outer membrane since it appears to interact with the peptidoglycan on the inner side of this membrane while it is known to be accessible to both phages and antibodies at the cell surface.

Isolation and properties of suppressor-sensitive mutants of Bacillus subtilis bacteriophage SP02.

Suppressor-sensitive mutants of Bacillus subtilis phage SPO2 were isolated and classified into 18 cistrons. A linear genetic map was constructed. The genes controlling early functions of phage development were clustered near the CI gene which may produce phage repressor.