A randomized trial of povidone-iodine compared with iodine tincture for venipuncture site disinfection: effects on rates of blood culture contamination.

BACKGROUND: Contamination of blood cultures creates problems in their interpretation and unneeded resource utilization. Because skin flora comprise the major group of contaminant species, more effective skin disinfection at the venipuncture site could reduce contamination. SUBJECTS AND METHODS: We performed a randomized trial in adult inpatients at a tertiary care teaching hospital. Antecubital venipuncture sites were randomly disinfected with povidone-iodine or iodine tincture, and blood cultures (two bottles, 10 mL of blood) were drawn by professional phlebotomists. Scoring of contaminant species was restricted to skin flora. Hospital resource utilization was compared among patients with contaminated blood cultures and those with sterile blood cultures. RESULTS: Of the 3,851 blood cultures collected during the study, 120 (3.1%) were contaminated with skin flora. The contamination rate for blood cultures collected after povidone-iodine was 3.8% (74 of 1,947), compared with a rate of 2.4% (46 of 1,904, P = 0.01) after iodine tincture. The difference in mean total hospital costs for patients with contaminated blood cultures and those with sterile blood cultures was $4,100 (95% confidence interval: $740 to $7,400, P = 0.02). CONCLUSIONS: Iodine tincture is superior to povidone-iodine for venipuncture site antisepsis before blood culture sampling. Because of the high costs associated with contaminated blood cultures, hospitals should consider switching from povidone-iodine to iodine tincture. Reduction of the contamination rate may improve the quality of patient care and reduce hospital costs.

Source of elastin-degrading enzymes in mycotic aortic aneurysms: bacteria or host inflammatory response?

Elastolytic matrix metalloproteinases play a central role in the development of chronic atherosclerotic aortic aneurysms, but mycotic aortic aneurysms are a distinct and unusual form of aneurysm disease caused by bacterial infection. Mycotic aortic aneurysms follow a more rapid and unpredictable course than chronic aneurysm disease and they exhibit a predilection for the suprarenal aorta, further implying unique pathophysiologic mechanisms. The purpose of this study was to examine the nature and source of elastin-degrading enzymes in mycotic aortic aneurysm. Bacterial isolates and aortic tissues were obtained from four consecutive patients undergoing surgical repair of suprarenal mycotic aortic aneurysm. Using an in vitro 3H-labeled elastin degradation assay, elastin-degrading enzyme activity was only observed in the bacteria-conditioned medium from an isolate of Pseudomonas aeruginosa. Elastin-degrading enzyme activity in the aortic tissue homogenate of this patient was abolished by the serine protease inhibitor, phenylmethylsulfonyl fluoride, but it was not suppressed by the metalloproteinase inhibitor, ethylenediamine tetraacetic acid (EDTA). In contrast, elastin-degrading enzyme activity in the bacterial-conditioned medium was decreased by about half by both phenylmethylsulfonyl fluoride and EDTA. Elastin substrate zymography revealed two phenylmethylsulfonyl fluoride-inhibitable elastin-degrading enzyme activities in the aortic tissue homogenate that corresponded to human neutrophil elastase (approximately 30 kDa) and its stable complex with alpha 1-proteinase inhibitor (approximately 80 kDa), but no activity attributable to Pseudomonas elastase, a 33-kDa metal-dependent enzyme. Human neutrophil elastase was readily detected throughout mycotic aortic aneurysm tissues by immunohistochemistry, but elastolytic metalloproteinases were only occasionally observed. The results of this study suggest that the elastin-degrading enzyme produced in mycotic aortic aneurysm are largely serine proteases of host neutrophil origin, rather than elastases produced by the infecting microorganisms or the macrophage-derived metalloproteinases typically observed in atherosclerotic aneurysm disease. Further studies will be needed to extend these findings to a larger number of patients with mycotic aortic aneurysm and those caused by additional microorganisms.

Microbial growth inside saline-filled breast implants.

In vitro and in vivo experiments were conducted to determine whether intraluminal saline in breast implants can support the growth of common wound-infecting microorganisms over a prolonged period of time. The bacteria tested were Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Corynebacterium jeikeium, Enterobacter cloacae, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Three fungal species also were tested: Aspergillus fumigatus, Paecilomyces variotii, and Candida albicans. In the in vitro study, four organisms survived in flasks of sterile saline for the 2 weeks in which serial cultures were performed: K. pneumoniae, C. albicans, A. fumigatus, and P. variotii. In the in vivo study, 61 white rabbits (122 implants) received both an experimental implant inoculated with one of the test organisms and a control implant containing only sterile saline. They were sacrificed at 1-, 3-, or 6-month scheduled endpoints. None of the control implants containing sterile saline had positive cultures. In contrast, the intraluminal saline was culture positive for 7 of the 10 inoculated organisms after varying lengths of time: S. epidermidis, E. coli, E. cloacae, K. pneumoniae, P. aeruginosa, A. fumigatus, and P. variotii. Samples of capsular tissue also were cultured. Of the 122 capsular tissue specimens, 21 (17 percent) had positive cultures and surrounded both inoculated and sterile implants. In most instances, capsules that were culture positive contained an organism different from the one that had been inoculated in the group. In only 3 cases was the same organism cultured from both the periprosthetic tissue and the intraluminal saline, and these may represent instances of the inoculated organism migrating through the implants filler valves. The data show that several types of bacteria (particularly gram-negative species) and fungi can grow and reproduce in a restricted saline environment for extended periods of time.

Paecilomyces variotii contamination in the lumen of a saline-filled breast implant.

This report describes a case of gross contamination with the filamentous fungus P. variotii cultured from an intraluminal saline breast implant removed from a patient 14 months after implantation because of severe capsular contracture. We suspect the fungal contamination occurred when a container of saline was left open in the operating room prior to filling and placement of the implant. This case may be the first documented report of microbial growth and reproduction in the internal environment of a saline implant. We assume that organisms such as P. variotii can survive--and accumulate biomass--on the minute amounts of substrates that diffuse across an implant envelope.

Prevalence of Corynebacterium urealyticum in urine specimens collected at a university-affiliated medical center.

Corynebacterium urealyticum (formerly Corynebacterium group D2) has been implicated as a cause of alkaline-encrusted cystitis and urinary tract struvite calculi. Despite preselecting urine specimens with neutral and alkaline pHs and using prolonged incubation on a selective medium, isolation of this organism was rarely observed in a population of hospitalized patients. We do not recommend routine cultures for this organism unless the urine is alkaline and struvite crystals, leukocytes, and erythrocytes are present.

Patrones de sensibilidad de los aislados de Haemophilus de ninos de once países en desarrollo / Antimicrobial susceptibility patterns of Haemophilus isolates from children in eleven developing countries

Antimicrobial susceptibility patterns of Haemophilus isolates from children in eleven developing nations

Evaluation of microparticle enzyme immunoassays for immunoglobulins G and M to rubella virus and Toxoplasma gondii on the Abbott IMx automated analyzer.

The ability of the Abbott IMx automated analyzer to detect immunoglobulin G (IgG) and IgM antibodies to rubella virus and to Toxoplasma gondii was compared with the abilities of RUBAZYME, RUBAZYME-M, ABBOTT TOXO-G enzyme immunoassay, and ABBOTT TOXO-M enzyme immunoassay, respectively. Specimens that produced discordant results were evaluated by RUBACELL II, Behring Enzygnost-Rubella enzyme-linked immunosorbent assay, Behring Enzygnost Toxoplasmosis/IgG, and bioMerieux Toxo-ISAGA (immunosorbent agglutination assay), respectively. After resolution of discordant results, IMx Rubella IgG, IMx Rubella IgM, IMx Toxo IgG, and IMx Toxo IgM antibody assays had sensitivities of 99.9, 100, 98.0, and 100%; specificities of 98.9, 99.0, 97.5, and 98.7%; and accuracies of 99.8, 99.3, 97.8, and 98.8%, respectively.

In vitro susceptibility studies of vancomycin-resistant Enterococcus faecalis.

Vancomycin resistance exhibited by Enterococcus faecalis isolates V583, V586, and V587 is described. The vancomycin MICs ranged from 32 to 64 micrograms/ml. Although resistant to vancomycin, the isolates were susceptible to teicoplanin (MIC, less than or equal to 0.5 micrograms/ml). Such a glycopeptide susceptibility profile has not been previously described for E. faecalis. Time kill studies showed that vancomycin resistance adversely affected the synergistic activity that vancomycin and aminoglycoside combinations usually demonstrate against enterococci. However, the ability to detect vancomycin resistance varied with the susceptibility testing method used. Whereas broth microdilution, broth macrodilution, and agar dilution methods detected resistance, disk-agar diffusion and the AutoMicrobic system Gram-Positive GPS-A susceptibility card (Vitek Systems Inc., Hazelwood, Mo.) did not. To detect vancomycin resistance reliably and establish the incidence of such E. faecalis isolates, adjustments in some susceptibility testing methods may be necessary.

Evaluation of the modified Bac-T-Screen and FiltraCheck-UTI urine screening systems for detection of clinically significant bacteriuria.

Previous evaluations of the Bac-T-Screen system (Vitek Systems, Inc., Hazelwood, Mo.) demonstrated excellent sensitivity with specimens from patients with clinically significant bacteriuria (including infections with small numbers of uropathogens) but poor specificity with specimens from noninfected patients. In the study reported here, the sensitivity and specificity of the Bac-T-Screen system with a modified decolorizing reagent were evaluated. A manual filtration system, FiltraCheck-UTI (Vitek Systems), for screening urine specimens, Gram stains of mixed urine specimens, and quantitative cultures were also evaluated. The test sensitivity for clinically significant bacteriuria was greater than 96% with the original Bac-T-Screen system as well as the modified system and the manual system. In comparison, the sensitivities of the Gram stains and quantitative cultures (greater than or equal to 10(5) CFU/ml) were 82 and 77%, respectively. Of the 375 patients classified as noninfected by clinical parameters, 34% had positive screening tests with the original Bac-T-Screen system, as compared with 13 and 11% with the modified Bac-T-Screen and FiltraCheck-UTI systems, respectively. Thus, the modified Bac-T-Screen system and the manual FiltraCheck-UTI system have sensitives comparable to that of the original Bac-T-Screen system and markedly improved test specificities.

Effect of decontamination procedures on recovery of Nocardia spp.

Exposure to 0.5% N-acetyl-L-cysteine (NAC), 2% NaOH-NAC, or benzalkonium chloride in trisodium phosphate (Zephiran-TSP) was toxic for Nocardia isolates. The number of viable Nocardia cells in a standardized suspension was reduced by 10(2) to 10(6) after a 30-min exposure to 2% NaOH-NAC and by 10(4) or more after a 30-min treatment with Zephiran-TSP.

Comparative study of the ability of four aminoglycoside assay techniques to detect the inactivation of aminoglycosides by beta-lactam antibiotics.

In vitro inactivation of aminoglycosides (tobramycin, gentamicin, and amikacin) by beta-lactams (cefazolin, cefotaxime, moxalactam, carbenicillin, piperacillin, mezlocillin, and azlocillin) was measured using the enzyme-mediated immunoassay (EMIT), fluorescence polarization immunoassay ( TDX ), radioimmunoassay (RIA), and bioassay. No significant inactivation of aminoglycosides was produced by high levels of the three cephalosporins as measured by EMIT, RIA, or bioassay. Inactivation of tobramycin and gentamicin by mezlocillin and azlocillin was comparable to that seen with piperacillin but less than that with carbenicillin. In general, the bioassay detected the greatest degree of aminoglycoside inactivation and the EMIT assay detected the least for all drug combinations. The TDX and RIA techniques were equivalent in their ability to detect aminoglycoside inactivation by beta-lactam antibiotics.

Heparin interferes with the radioenzymatic and homogeneous enzyme immunoassays for aminoglycosides.

Heparin interferes with measurement of aminoglycosides in serum by biological, radioenzymatic, and homogeneous enzyme immunoassay techniques, but not with radioimmunoassay. At concentrations greater than or equal to 10(5) and greater than or equal to 3 X 10(6) USP units/L, respectively, it interferes with the radioenzymatic assay by inhibiting the gentamicin 3-acetyltransferase (EC 2.3.1.60) and kanamycin 6'-acetyltransferase (EC 2.3.1.55) enzymes used in the assay. It interferes with the homogeneous enzyme immunoassays for gentamicin and tobramycin (at concentrations greater than or equal to 10(5) and greater than or equal to 10(4) USP units/L, respectively), but not with the commercially available homogeneous enzyme immunoassays for other drugs. Heparin interference with the homogeneous enzyme immunoassay for aminoglycosides requires both the heparin polyanion and glucose-6-phosphate dehydrogenase (EC 1.1.1.49) bound to a cationic aminoglycoside. This interference can be reproduced with dextran sulfate (but not dextran), and does not occur with free enzyme (glucose-6-phosphate dehydrogenase) alone. We describe how heparin interferes with these two assays and demonstrate interference at heparin concentrations that may be present in intravenous infusions or in seriously underfilled blood-collection tubes.

Rapid presumptive identification of anaerobes in blood cultures by gas-liquid chromatography.

Production of volatile and nonvolatile metabolic acids in blood culture broths by aerobic, facultative anaerobic, and obligate anaerobic bacteria was analyzed by gas-liquid chromatography. Anaerobic blood culture isolates were presumptively identified by the qualitative analysis of volatile fatty acids. Isolates, with a characteristic Gram stain reaction and cellular morphology, were identified by the following acid patterns: Bacteriodes fragilis group with acetic and propionic acids; Fusobacterium with acetic, butyric, and usually propionic acids; Veillonella with acetic and propionic acids; gram-positive cocci with acetic and butyric acids; and Clostridium with acetic and butyric acids.

Growth of clinical isolates of anaerobic bacteria on agar media: effects of media composition, storage conditions, and reduction under anaerobic conditions.

The quantitative growth, the colony size, and the rate of growth of 47 clinical anaerobic isolates were compared on five different media, namely Brucella agar, brain heart infusion agar, Columbia agar, Schaedler agar, and tryptic soy agar. There was no significant difference in the quantitative growth of the anaerobes inoculated onto the five media. Although no single medium was superior for the growth of all isolates, 12 of 22 isolates, inoculated onto media stored for 4 weeks or less, grew best on Schaedler agar. The effects of supplementation of the media with reducing agents and reduction of the media before use were also analyzed and were found to be affected by the composition and length of storage of the media, as well as the bacteria tested.

Microscopic and baceriologic analysis of expectorated sputum.

Samples of expectorated sputum were examined grossly and microscopically to determine their suitability for bacterial cultures. Microscopically, specimens were categorized according to the number of leukocytes and squamous epithelial cells (SEC) observed under low-power (times 100) in a Gram-stained smear. The mean number of species isolated was greater than 4 from specimens with more than 10 SEC per field, 2.7 from specimens with fewer than 10 SEC per field, and 2.4 from transtracheal aspirates. Oropharyngeal flora was isolated from nearly all of the specimens with more than 10 SEC per field, and potential pathogens were found in less than 15% of such specimens. The bacterial flora of specimens with fewer than 10 SEC per field closely resembled that of transtracheal aspirates.

Characterization of bromodeoxyuridine-induced endogenous guinea pig virus.

An endogenous virus (GPV) was induced after 5-bromodeoxyuridine treatment of cultured guinea pig cells. Compared to Gross murine leukemia virus (G-MuLV) GPV has a reproducibly heterogenous density of about 1.16 to 1.18 g/ml. The virion-associated RNA is slightly larger than that in G-MuLV. Sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis of dissociated GPV resolved five major structural proteins: I (molecular weight 70,000), II (molecular weight 36,000), III (molecular weight 24,000), IV (molecular weight 18,000), and V (molecular weight 16,000) which are similar to but distinct from G-MuLV proteins. Proteins I and II were demonstrated to be glycoproteins by incorporation of [(3)H]glucosamine. GPV and G-MuLV did not have any appreciable genetic homology or any common group-specific antigens when analyzed by immunodiffusion, radioimmunoassay, and indirect immunofluorescence. Morphogenesis of GPV also differed from that of a typical type C oncornavirus and proceeded via two pathways: (i) a majority of virus particles were formed in cytoplasmic vacuoles and were released after cellular disruption; and (ii) a minor population of particles were assembled in the cytoplasmic matrix and then migrated to the plasma membrane where they budded into the extracellular space. To date, GPV has been unable to initiate or maintain a productive replication in any cell line tested.

Induction of type C viruses in cultured guinea pig cells.

Particles morphologically resembling type C viruses were activated by bromodeoxyuridine (BUdR; 10(-4) M) treatment of cultured guinea pig cells. Virus particles were isolated from the cells of normal and leukemic strain 2 and random-bred guinea pigs (adult and embryonic). Immature virus particles with electron-lucent cores were found in the cytoplasmic matrix. The mature particles with electron-dense cores were found outside the cells and some appeared in the process of budding from the plasma membrane. The peak of virus production was observed within 4 days of BUdR treatment. When compared to the amount of virus produced in darkness, visible light enhanced virus production, whereas exposure of BUdR-treated cells to UV light either had no effect or inhibited virus production. Virus particles had a density of 1.16 gm/ml, possessed an oncornavirus-specific reverse transcriptase, and contained a large-molecular-weight RNA (65-70S) which dissociated into 36S subunits after heat denaturation. The BUdR-activated virus particles, therefore, possessed the morphological, biophysical, and biochemical characteristics of type C oncornaviruses.