Multicenter comparison of BACTEC 9050 and BACTEC 9240 blood culture systems.

The overall recovery of organisms and time to detection with the BACTEC 9050 and BACTEC 9240 systems were compared in a multicenter evaluation. In the first phase of the study, a total of 4,383 compliant aerobic (Plus Aerobic/F) blood culture sets were processed. There was no significant difference in the recovery of individual groups of organisms with the two systems, with the exception of Streptococcus pneumoniae which was isolated more frequently with BACTEC 9050. False-positive signals occurred more often with BACTEC 9240 (58 cultures) than with BACTEC 9050 (43 cultures), but false-negative cultures were uncommon with both systems (3 cultures for each system). Time to detection of positive cultures of clinically significant organisms was essentially the same with both instruments. In the second phase of the study, 2,431 compliant anaerobic (Plus Anaerobic/F) blood culture sets were processed. There was no significant difference in the recovery of organisms with BACTEC 9050 compared with BACTEC 9240. Significantly (P < 0.03) more false-positive signals occurred with BACTEC 9240 (15 cultures) than with BACTEC 9050 (4 cultures). Likewise, more false-negative cultures occurred with BACTEC 9240 (11 cultures) than with BACTEC 9050 (8 cultures). Time to detection of positive cultures of clinically significant organisms was essentially the same with both systems with the exception of anaerobes (N = 10), which were recovered earlier (P < 0.01) with BACTEC 9240 (35.0 h) than with BACTEC 9050 (61.4 h).

Clinical comparison of the BACTEC 9000 Standard Anaerobic/F and Lytic/F blood culture media.

An 8-month prospective, volume controlled, comparison of Standard Anaerobic/F media with a new anaerobic high blood volume lytic medium (Lytic/F) was performed. A total of 2,092 compliant sets, consisting of an aerobic resin bottle or standard aerobic bottle, Standard Anaerobic/F, and Lytic/F bottle were evaluated. A total of 220 (10.6%) positive specimens were detected from the paired anaerobic bottles. These consisted of 194 true positive and 26 false positive bottles. Of 207 total organisms isolated, 122 were considered clinically significant. A comparison of significant organism recovery revealed 79 isolates in both anaerobic bottles, 7 isolates in the standard Anaerobic/F bottle only, and 36 isolates in the Lytic/F bottle only (p < 0.001). The lytic/F bottle detected significantly more Enterobacteriaceae (p < 0.005) and Streptococci (p < 0.05). There were 24 false positive Standard Anaerobic/F bottles and 2 false positive Lytic/F bottles (p < 0.001). When both bottles were positive the Standard Anaerobic/F bottle was positive 12 hours earlier in 1 instance whereas the Lytic/F bottle was positive 12 hours earlier in 8 instances. The mean time for detection in the Standard Anaerobic/F bottle was 18.2 hours versus 13.2 hours for the Lytic/F bottle. The new Lytic/F anaerobic blood culture media was found to be superior to Standard Anaerobic/F media for both total organism recovery and time to organism detection.

Continuous ambulatory peritoneal dialysis complicated by Aureobasidium pullulans peritonitis.

We describe a case of peritonitis caused by Aureobasidium pullulans in a patient on continuous ambulatory peritoneal dialysis (CAPD). This dematiaceous fungus rarely causes infection in humans and to date has not been reported as an etiology of CAPD-associated peritonitis. The patient was managed successfully with peritoneal catheter removal and a prolonged course of intravenous amphotericin B, allowing resumption of CAPD. In vitro susceptibility testing confirmed sensitivity of this organism to amphotericin B.

Evaluation of the Pasco gram-negative nonfermenter identification system.

The Pasco Gram-negative identification system was evaluated for use with nonfermenting organisms. Of 127 isolates tested, 109 (86%) were correctly identified to the species level. A total of 91% (93 of 102 isolates) of the Pseudomonas-Xanthomonas group and the Acinetobacter group were correctly identified to the species level. The system was found to be useful for the identification of Pseudomonas aeruginosa, Xanthomonas maltophilia, and Acinetobacter species.

Direct examination of unstained smears for the evaluation of sputum specimens.

We compared examination of unstained and Gram-stained smears as methods of evaluating sputum quality. Of 100 slides examined, 96 (96%) were graded identically. Each discrepancy between methods was near the cutoff for specimen acceptability. We concluded that examination of unstained smears can provide an accurate, cost-effective sputum screening method.

Evaluation of human hair sources for the in vitro hair perforation test.

The in vitro hair perforation test for dermatophytes was evaluated with hair from males and females aged 6 months to 67 years, including hair of various natural colors and hair which had been bleached, tinted, curled, sprayed, or subjected to various combinations of these treatments. In contrast to published recommendations, the source of hair had no effect on this diagnostic procedure.

Characterization of endemic Providencia stuartii isolates from patients with urinary devices.

Providencia stuartii has emerged as a significant nosocomial urinary tract pathogen. An increase in the number of Providencia isolates from urine cultures prompted an investigation into the possibility of an outbreak due to this organism. A high proportion of patients studied had urinary devices. Four wards were screened at two time periods to ascertain the prevalence of Providencia stuartii in urine cultures. Biotype, serotype, antibiogram and plasmid content were determined for each Providencia isolate. Of 129 patients initially sampled 22.5% were found to harbor Providencia stuartii. Biotyping, serotyping and antibiograms indicated an epidemic strain was not present. Similar results were obtained when the wards were screened a second time, with 25.4% of urine cultures found to contain Providencia stuartii. By plasmid analysis the isolates could be grouped into one of ten profiles. A correlation could be made between urease activity and the presence of a large plasmid. No association however could be made between a particular plasmid profile and antibiogram. The data indicate that an epidemic strain of Providencia stuartii was not present. The source(s) of the endemic Providencia stuartii strains remain unknown.

Activity of apalcillin against Pseudomonas aeruginosa.

The in vitro activity of apalcillin was tested against 107 clinical isolates of Pseudomonas aeruginosa, and the results were compared to those for piperacillin, mezlocillin, azlocillin, and carbenicillin. MIC analysis showed that 97% of the isolates were susceptible to piperacillin, 97% were susceptible to apalcillin, 93% were susceptible to azlocillin, 87% were susceptible to mezlocillin, and 84% were susceptible to carbenicillin.

Use of the Autobac IDX system for rapid identification of Enterobacteriaceae and nonfermentative gram-negative bacilli.

The Autobac IDX system was evaluated for its ability to accurately identify 290 gram-negative bacilli from 18 different genera. Excluding isolates with a low identification probability, the overall sensitivity of the system was found to be 95.8%. Late lactose-fermenting Escherichia coli, Citrobacter freundii, and Proteus mirabilis accounted for over 90% of the misidentifications. The Autobac IDX system offers a rapid and reliable method for the identification of gram-negative bacilli.

Increased Efficiency of Group B Coxsackievirus Isolation from Clinical Specimens by Use of BGM Cells.

A continuous African green monkey kidney cell line, designated BGM, was compared with primary cynomolgus monkey kidney cells and human embryonic lung cells for efficiency of enterovirus isolation. A selective enhanced sensitivity of BGM cells both in terms of isolation rate and speed of isolation was found for group B coxsackieviruses but could not be demonstrated for a number of other nonpolio enteroviruses.

Enzymatic activities of Legionella pneumophila and Legionella-like organisms.

The API ZYM system was used to investigate enzymatic activities of Legionella pneumophila and other Legionella-like organisms. Leucine aminopeptidase, alkaline and acid phosphatase, butyrate and caprylate esterase, and phosphoamidase activities were consistently detected in all strains tested. No evidence of myristate lipase, trypsin, chymotrypsin, or glycosidase activity was found.

Allergic bronchopulmonary aspergillosis with low serum immunoglobulin E.

Elevated total serum IgE is helpful in making the diagnosis of ABPA and in monitoring the onset of exacerbations and response to therapy. ABPA occurs frequently in patients with CF, and in these instances a high total serum IgE is seen. This is the first case report of ABPA without an elevated total serum IgE level. At no time prior to this patient's first episode of ABPA, at the time of the illness, or at monthly intervals during follow-up did her total serum IgE level exceed 29 IU/ml.

Crossed immunoelectrophoretic analysis of two antigen extracts of Thermoactinomyces candidus.

A pyridine extract antigen and a double-dialysis antigen (DDA) obtained from Thermoactinomyces candidus were analyzed by crossed immunoelectrophoresis. In addition, the heat lability, pronase sensitivity, and isolectric points of the components of the DDA were determined. By using antisera raised against crude pyridine extract antigen, two immunogenic components were resolved by crossed immunoelectrophoresis. A similar analysis of DDA using antisera raised against crude DDA revealed 15 immunogens. All but six components were heat labile, whereas pronase had little effect on the number of resolvable components. Intermediate gel crossed immunoelectrophoresis using antiserum raised to whole spores detected six immunogenic components, four of which were also detected by the anti-DDA serum. A total of 19 bands were obtained when the DDA was subjected to flatbed isoelectric focusing on polyacrylamide gels. The isoelectric points for the various components were found to range from 3.5 to 5.7. Crossed immunoelectrophoresis using isoelectric focusing in the first dimension yielded at least 16 immunogenic components. Six components with isoelectric points falling in the range of 4.5 to 6.4 were found to be resistant to heat. A comparison with antigens obtained from other thermophilic actinomycetes is presented.

The efficacies of common dyes in primary isolation media for recovery of pathogenic fungi.

Dyes incorporated into a basal medium of brain heart infusion, Sabhi, tryptic soy, or yeast extract--pepton--glucose (YxPG) agar for selective isolation of fungi were investigated. Dilutions of 1:500, 1:750, 1:1,000, 1:5,000, and 1:10,000 of 33 common dyes were tested against 11 gram-positive and 16 gram-negative bacteria. In addition, these dyes were tested against Cryptococcus neoformans, Candida albicans, and the dimorphic phases of Histoplasma capsulatum and Blastomyces dermatitidis. Twenty-one of the dyes did not inhibit any of the organisms tested. Brilliant green, gentian violet, and malachite green (at three dilutions) inhibited all the organisms tested. Methyl red was found to be the best dye in selecting for fungi. Several dyes were also found to inhibit selectively C. neoformans or C. albicans and the dimorphic fungi H. capsulatum or B. dermatitidis.

Comparison of primary rhesus and cynomolgus monkey kidney cell cultures for viral isolation from clinical specimens.

Rhesus monkey kidney and cynomolgus monkey kidney cell cultures were compared for viral isolation by using clinical specimens that yielded 203 viral isolates. Cynomolgus and rhesus monkey kidney cells were comparable for the isolation of 22 adenoviruses, 12 coxsackieviruses, and one poliovirus. Four of 50 echoviruses and seven of ten herpesviruses were detected only in cynomolgus monkey kidney cells. Influenza virus was isolated in 84 instances, of which eight were detected only in rhesus and four only in cynomolgus monkey kidney cells. Rhesus monkey kidney cells yielded six more parainfluenza virus isolates. Except possibly for parainfluenza virus, cynomolgus monkey kidney cells appear to be as sensitive as rhesus monkey kidney cells for viral isolation from clinical specimens.

Comparison of direct and standardized disk diffusion susceptibility testing of urine cultures.

A comparison between direct and standardized disk diffusion tests was made on a total of 300 urine specimens containing >/=10(5) organisms/ml. Of these, 246 represented pure cultures and 54 represented mixed cultures. The number of major discrepancies per organism tested in pure culture was 18 (7.3%) and in mixed cultures it was 23 (42.6%). The percentage of major discrepancies per total number of antimicrobial drug comparisons made was 1.4%. Although this procedure may be of value in selected cases with pure cultures of organisms present in quantities >/=10(5)/ml, its use on a routine basis is not recommended.

Evaluation of the API 20 c microtube system for the identification of clinically important yeasts.

The API 20 C microtube system containing 20 biochemical tests for the identification of yeasts was compared with conventional tests used in the Mayo Clinic mycology laboratory. Three hundred isolates of clinically important yeasts were studied, and agreement of the carbohydrate fermentation and assimilation tests between the systems was good. The API 20 C represents a useful, commercially available screening method for the identification of yeasts; however, it is not a complete system and must be used in conjunction with microscopic morphological features and, when appropriate, with other biochemical tests.