To better understand the role of plasmids and their importance in the endemic antibiotic resistance of Enterobacteriaceae, we began a prospective study of our combined medical intensive care/coronary care unit. An initial culture survey of the patients, ward staff, and environment was followed by a prospective sampling of 139 consecutive new admissions at the time of admission to the unit, and at regular intervals thereafter for the remainder of their stay. All cultures were planted on agar-containing gentamicin. Of the 147 patients studied, 12 (8.2%) were colonized with 20 strains of gentamicin-resistant gram-negative bacilli (GRGNB) at 29 sites. An additional four GRGNB were isolated from the environment. Of the 24 GRGNB strains, 7 (29%) Enterobacteriaceae carried plasmids shown to carry the gentamicin-resistance determinant. Plasmids were further characterized by restriction endonuclease digestion profiles of plasmid DNA purified from E. coli C600 transconjugants or transformants. A 93 kb plasmid introduced to the unit by a Serratia liquefaciens colonizing a patient transferred from another area in the hospital was identical to 93 kb plasmids carried by a C. amalonaticus and an E. aerogenes subsequently colonizing another patient on the unit. A 60 kb plasmid, first isolated from a S. marcescens colonizing a sink drain was later isolated from an E. cloacae colonizing a patient. Our results indicate that spread of specific R-plasmids may be one mechanism for dissemination of antibiotic resistance on our MICU/CCU.

The endemic R-plasmids mediating resistance to gentamicin and multiple other antibiotics among many species of Enterobacteriaceae from the Minneapolis and Cleveland Veterans Administration Medical Centers were compared by restriction endonuclease digestion profiling and by phenotype expressed in sensitive E. coli recipients. Southern hybridizations were also performed. Our data indicate that these plasmids demonstrate some microheterogeneity, but are very closely related. Both are self-transferable and mediate resistance to ampicillin, carbenicillin, chloramphenicol, gentamicin, tobramycin, neomycin and kanamycin. These results suggest the dissemination of a conjugal R-plasmid or of Enterobacteriaceae bearing the plasmid between two midwestern Veterans Administration Medical Centers. The most likely mechanism of transmission may be the frequent transfer of patients between midwestern Veterans Administration Medical Centers.

A low rate of seroconversion to hepatitis B vaccine is reported. This occurred in healthy hospital employees from two separate institutions. A total of 236 individuals were evaluated in this study and only 53% or 124 persons developed protective levels of antibody to hepatitis B surface antigen following a complete vaccine series. In one hospital, 30% of the vaccine recipients developed antibody but not to a protective level. Employees who received the entire series in the arm or in the arm and buttock (mixed) had a significantly greater number of responders than employees who received the entire series in the buttock (P<.05). Recipients aged 50 to 59 years had a significantly lower response rate to the vaccine (P<.05). There was no correlation with the vaccinee's sex or the timing of the second injection. Vaccine was noted to have frozen in one hospital and accounted for some loss of antigenicity. This failure to respond to the vaccine has necessitated the use of booster injections of vaccine and continued antibody monitoring.

Standardized suspensions of 78 staphylococci and micrococci were stored in different diluents and tested periodically for 3 weeks to determine their ability to maintain viability. In 92% of the tests, diluent suspensions yielded viable organisms for at least 21 days. Organism survival was maintained in the following order, from best to worst: skim milk, tap water, 0.9% NaCl, deionized water, Dianeal (peritoneal dialysis) fluid, 0.2% bovine serum albumin and 5% glycerol. In 81% of the instances, oxacillin-susceptible staphylococci survived better than oxacillin-resistant staphylococci.

In vitro fertilization and embryo transfer (IVF-ET) is a process in which human ova are obtained by laparoscopic ovarian follicular puncture, fertilized in vitro by capacitated donor sperm, and introduced transcervically into the uterus. The prospective mother's ovarian cycle is usually stimulated with either clomiphene citrate, human menopausal gonadotropin, or both, so that multiple aspiratable follicles are produced. Follicular development is monitored by ultrasound and by serial serum or urine estrogen determinations. When adequate follicular development has been achieved, a pre-ovulatory dose of human chorionic gonadotropin is administered.

Herpes simplex virus (HSV) causes a variety of illnesses in th e community and hospital settings (Table). Nosocomial infections with this virus may result from: 1) reactivation of latent infection, especially in patients whose immune systems are compromised; 2) spread from mother to infant; 3) spread from patients to hospital personnel; 4) spread from hospital personnel to patients; and 5) cross-infection among patients. The latter two possibilities seem to occur infrequently but merit some discussion because of the serious implications of such infections.