We used a typing system based on bacteriophage and bacteriocin susceptibility to study the epidemiology of Clostridium difficile colonization of newborn infants. C. difficile was found in the stools of 30 (16.0%) of 187 infants who were screened. Increased length of stay in the nursery (P less than .001) and delivery by cesarian section (P less than .001) were associated with higher rates of colonization. The isolates initially detected from the environment and the infants were strain B1811-1700. Strain B1537/Cld7 became the predominant isolate obtained from the infants; positive cultures were also obtained from the environment and the hands of personnel who worked in the nursery and had strain B1537/Cld7. Our results suggest that the infants acquired C. difficile through transfer from the hands of hospital staff.

Many clinicians are trying unique strategies, including vancomycin and linezolid in combination, for treatment of patients who do not respond to conventional therapy against methicillin (meticillin)-resistant Staphylococcus aureus. In our study, which illustrated in vitro activity only, no synergistic activity was seen when the two agents were combined. Conversely, antagonistic activity occurred in three of five strains when linezolid was added to vancomycin. Our results indicate that vancomycin and linezolid in combination should be avoided.

Serum immunoglobulin G (IgG) class antibodies directed against toxins A and B of Clostridium difficile were studied using an enzyme-linked immunosorbent assay and a serum-neutralizing assay based on the MRC-5 tissue cytotoxicity assay. Of 185 individuals, 46 sera (24%) in the general population demonstrated IgG antibody, 36 (19.4%) against toxin A and 15 (8.1%) against toxin B. Antibody titer in the general population did not correlate with serum-neutralizing activity. Antibody prevalence fell with age (P = 0.58) over 50 years. Six of ten patients with acute primary episodes of C. difficile-associated diarrhea demonstrated antibody in convalescent-phase sera, predominantly directed against toxin B. Only two (28%) of seven patients with a history of relapsing C. difficile disease had demonstrable antibody.

Two patients developed serious enterococcal superinfection following therapy with intravenous ciprofloxacin. The strains causing bacteraemia were susceptible to low concentrations of ciprofloxacin when tested at a standard inoculum. However, at an inoculum of 1 X 10(7) cfu/ml they were resistant to high concentrations of ciprofloxacin. Our data suggest that ciprofloxacin should not be used to treat patients with serious enterococcal infection and that patients treated with ciprofloxacin should be monitored carefully for the development of enterococcal superinfection.

The overall prevalence of CA-MRSA colonization in a random sample of healthy individuals in 4 non-healthcare locations in Newark and Wilmington was 1.0%. Despite concerns that the prevalence of MRSA colonization is increasing, it still remains relatively low in our community, perhaps because CA-MRSA colonization tends to occur in clusters.