Marcus J. Zervos

Association of contaminated gloves with transmission of Acinetobacter calcoaceticus var. anitratus in an intensive care unit

PURPOSE Acinetobacter calcoaceticus var. anitratus is an important nosocomial pathogen that has been associated with environmental reservoirs. An increased isolation rate of A. anitratus in our intensive care units (ICUs), from 0.03% (two of 7,800) to 0.5% (seven of 1,300) (p less than 0.00003), prompted an investigation. PATIENTS, METHODS, AND RESULTS Ten patients were admitted to the surgical ICU and nine to the medical ICU during the outbreak period (late December 1987 to January 1988). Controls were all patients on the units who were not infected or colonized with the transmitted strain of A. anitratus. Three patients had A. anitratus pneumonia. A throat culture prevalence survey demonstrated three patients colonized with A. anitratus. Cases were placed in a cohort and symptomatic cases treated. An epidemiologic investigation was conducted to identify reservoirs and modes of transmission. Latex gloves were being used for universal precautions without routine changing of gloves between patients. Environmental sources culture-positive for A. antitratus included a small volume medication nebulizer and gloves in use for patient care. Plasmid typing showed that plasmid profiles of isolates from two symptomatic patients, two colonized patients, the nebulizer, and the gloves were identical. Other A. anitratus ICU isolates had distinct plasmid profiles. All patients with the transmitted strain had been in the surgical ICU. The need for changing gloves between patients and contaminated body sites was reinforced. CONCLUSION Gloves, used incorrectly for universal precautions, may potentially transmit A. anitratus.

The epidemiology of pseudallescheriasis complicating transplantation: nosocomial and community-acquired infection.

The epidemiology of two cases of pseudallescheriasis in organ transplant patients are described and the disease in that population is reviewed. Disseminated hospital‐acquired infection occurred in a liver transplant recipient and was fatal despite therapy with miconazole. A heart transplant recipient developed localized disease following soil contamination of soft tissue trauma which was cured with surgical resection and miconazole therapy. Itraconazole showed in vitro activity against Pseudallescheria boydii and should be evaluated in pseudallescheriasis. P. boydii infections are important complications of transplantation and should be considered in the differential diagnosis of community‐acquired as well as nosocomial fungal infections in this population.

Heterogeneity of plasmids determining high-level resistance to gentamicin in clinical isolates of Streptococcus faecalis.

Between November 1981 and October 1984, 48 of 3,458 clinical isolates of Streptococcus faecalis at the University of Michigan Hospital showed high-level (greater than 2,000 micrograms/ml) resistance to gentamicin, as well as to all other clinically available aminoglycosides. Thirteen percent of clinical isolates in the University of Michigan Hospital currently demonstrate this level of resistance. Transfer of resistance to a plasmid-free streptococcal recipient was observed in filter matings for 44 of 48 such isolates. Analysis of transconjugants by agarose gel electrophoresis showed that gentamicin resistance was transferred alone in 8 isolates and was combined with other antimicrobial resistances on the same plasmid in the other 36 isolates. There were seven isolates which transferred the property of horse blood beta-hemolysis along with gentamicin resistance. Transfer of gentamicin resistance was either by conjugative plasmids or by a nonconjugative but mobilizable plasmid. Transfer frequencies on filters ranged from 4.7 X 10(-2) to 4.1 X 10(-8). Based on donor and transconjugant antibiotic resistance markers, agarose gel electrophoresis, transfer properties, and restriction enzyme analysis, the plasmid content of transconjugants was heterogeneous and could be classified into at least seven different patterns. These findings argue against clonal dissemination as the cause of the increased frequency of resistant strains and suggest that resistance to gentamicin appears on a variety of physically distinct conjugative and nonconjugative plasmids in S. faecalis. Images

Molecular characterization of highly gentamicin-resistant Enterococcus faecalis isolates lacking high-level streptomycin resistance.

Antimicrobial susceptibilities and DNA contents were analyzed for six clinical isolates of Enterococcus faecalis that had high-level resistance to gentamicin (MIC > 2,000 micrograms/ml) but not streptomycin and were obtained from patients in diverse geographic areas. Contour-clamped homogeneous electric field electrophoresis of genomic DNA showed all isolates to be different strains. Gentamicin resistance was transferred from four isolates to plasmid-free enterococcal recipients in filter matings. Restriction enzyme analysis of transconjugants showed distinct gentamicin resistance plasmids. A probe specific for the gentamicin resistance determinant hybridized to the plasmids of four isolates and to the chromosomes of two isolates. These findings suggest that clonal dissemination is not responsible for the spread of these resistant strains, that resistance determinants occur on different plasmids as well as on the chromosome of E. faecalis, and that the genetic determinants of resistance are related. Images

Characterization and comparison of two penicillinase-producing strains of Streptococcus (Enterococcus) faecalis.

We identified two beta-lactamase-positive enterococci. One strain was high-level (MIC, greater than 2,000 microgram/ml) gentamicin resistant; the other was not (MIC, 12.5 microgram/ml). beta-Lactamase production was extrachromosomally mediated in both strains, and both strains showed an inoculum effect reversed by beta-lactamase inhibitors. The strain lacking high-level gentamicin resistance showed synergistic killing with a combination of penicillin, clavulanic acid, and gentamicin.

Susceptibility and bactericidal activity studies of four β-Lactamase-producing enterococci

beta-Lactamase-producing (Bla+) enterococci are rare but have been reported from several areas. We report another Bla+ enterococcus with high-level gentamicin resistance. Susceptibility and bactericidal activity studies of four Bla+ enterococci against potential alternative antibiotics, including ampicillin-sulbactam, daptomycin, teicoplanin, and vancomycin, are presented.

Molecular epidemiology of β-lactamase-producing enterococci

Plasmids from the first six reported beta-lactamase-producing (Bla+) enterococci were compared for genetic relatedness. Bla+ enterococcal plasmids from strains isolated in Houston, Tex.; Philadelphia, Pa.; Connecticut; and Pittsburgh, Pa., had heterogeneous HaeIII and MspI-ClaI restriction endonuclease digestion patterns. A staphylococcal beta-lactamase probe hybridized to all six Bla+ enterococcal plasmids, but hybridization was detected on different HaeIII and MspI-ClaI fragments of the six plasmids. An enterococcal gentamicin resistance (Gmr) probe hybridized to a common 3.9-kilobase HaeIII fragment from the five Gmr plasmids. The Houston plasmid was cross-hybridized to the other five strains, and moderate to extensive homology was demonstrated. Bla+ enterococcal plasmids from a broad geographic range are heterogeneous with respect to size and restriction endonuclease digestion patterns but contain homologous genetic material, including Bla+ and Gmr determinants. Images

Mobilization of the penicillinase gene in Enterococcus faecalis.

Enterococcus faecalis SF4855 is a beta-lactamase-producing isolate resistant to high levels of gentamicin, with determinants for these resistances on the chromosome. SF4855 transferred both determinants into E. faecalis FA2-2 and UV202 at a frequency of 10(-9) in the presence of the MLS plasmid pYN120. beta-Lactamase and gentamicin resistance probes hybridized to three locations on the chromosome of FA2-2 transconjugants on contour-clamped homogeneous electric field electrophoresis. The study results suggest mobilization of the beta-lactamase determinant. Images