Hemophilus influenzae as a cause of urinary tract infections in men.

Hemophilus influenzae has rarely been reported to cause urinary tract infections, but media supportive of its growth are not routinely used for urine cultures. At two Veterans Administration medical centers, H influenzae was isolated from the urine of eight men in the past four years. All had anatomic or functional genitourinary abnormalities, and half had had chronic pyelonephritis or recurrent urinary tract infections. Three patients had acute cystitis, two patients had pyelonephritis, two patients had prostatitis, and one patient had asymptomatic bacteriuria with pyuria. Cases were discovered by primary isolation on chocolate agar or sheep's blood agar, by "satelliting" around staphylococci, or by positive urine Gram's stains. Urine Gram's stains disclosed organisms in all six nonprostatitis cases. Organisms were all nonserotypable, were of biotypes 2, 3, or 4, and were beta-lactamase negative. Hemophilus influenzae may be a more common uropathogen in adults than previously recognized.

Is the clean-catch midstream void procedure necessary for obtaining urine culture specimens from men?

To determine whether the results of voided urine cultures in men are affected by meatal cleansing, midstream sampling, or circumcision status, 308 paired (initial and midstream) specimens were collected from 254 urology clinic patients. Half of the patients cleansed their urethral meatus with povidone-iodine prior to voiding. The circumcision status of all patients was noted. The rates of true bacteriuria (growth of 10(4) or greater colony-forming units/ml urine with a single predominant species) and contamination (growth of 10(3) or greater colony-forming units/ml urine with two or more colonial types) were compared in the various collection technique subgroups. Neither the bacteriuria nor contamination rates were significantly different (p greater than 0.05) in circumcised and uncircumcised patients, or in those who cleansed their meatus and those who did not. Contamination, but not bacteriuria, rates were higher in initial as compared with midstream specimens. These data suggest that the clean-catch midstream void procedure is unnecessary for obtaining routine voided urine culture specimens from men.

Clinical application of the Mycobacterium tuberculosis direct test: case report, literature review, and proposed clinical algorithm.

The relatively new Mycobacterium tuberculosis direct test (MTDT) enzymatically amplifies M tuberculosis complex 16s ribosomal RNA. The sensitivity of the test ranges from 75 to 100%, with specificity of 95 to 100%, positive predictive value between 78% and 100%, and negative predictive value between 95% and 100%. Similar test characteristics have been documented in nonrespiratory specimens and in specimens that ultimately grow nontuberculous mycobacterium (NTM). This test allows for rapid identification of M tuberculosis in the smear-positive patient and may greatly improve sensitivity over acid-fast bacilli smear alone. A negative test result with a positive smear suggests infection with NTM or Mycobacterium avium complex. We present a case that illustrates the value of MTDT for analysis of tissue specimens in immunocompromised patients with suspected mycobacterial disease and review the rapidly developing literature about this test. We propose an algorithm using MTDT, acid-fast smear, and mycobacterial culture for the diagnosis and treatment of the immunocompromised patient with suspected mycobacterial infection.

Lack of clinical relevance in routine final subcultures of radiometrically negative BACTEC blood culture vials.

During a 38-month period, 10,106 blood specimens were received in the laboratory for culture. These were inoculated into 26,424 vials and processed using the BACTEC radiometric detection system. Of these vials, 1,914 were eventually found to be microbiologically positive. Isolates from 836 vials were judged to be contaminants. In the remaining 1,078 vials, growth was first detected visually or radiometrically in 1,062 and by final subculture in 16. Growth from these sixteen bottles represented 12 clinically significant bacteremic episodes in as many patients. In nine of these episodes, other culture vials from the same patient were positive radiometrically. Therefore, 358 of 361 (99.2%) bacteremic episodes were detected without the benefit of routine final subcultures. The three patients whose bacteremia was missed were diagnosed clinically and placed on appropriate therapy prior to the detection of the bacteremias by final subculture.

Suppurative granulomatous lymphadenitis caused by corynebacterium ovis (pseudotuberculosis).

A 30-year-old previously healthy man developed cervical adenopathy associated with mild constitutional symptoms. Corynebacterium ovis was isolated in pure culture from lymph node tissue on two separate occasions, and small gram positive organisms were identified in both lymph nodes with tissue gram stain. Histopathologically, the nodes displayed suppurative and necrotizing granulomas. Of eight previously reported cases of C. ovis lymphadenitis in man, all but one have involved inhabitants of rural Australia, most of whom had contact with sheep, an animal reservoir of C. ovis. Necrotizing granulomas were usually observed. The patient described was an American urban dweller with a history of raw milk ingestion. We believe this to be the first reported case of C. ovis lymphadenitis from the United States. C. ovis infection should be considered n the differential diagnosis of localized lymphadenitis with necrotizing and/or suppurative granulomas. In evaluation of granulomatous lymphadenitis tissue gram stain should be performed and culture of a diphtheroid organism not readily dismissed.

Increased detection of staphylococcal bacteremia using an anti-microbial removal device.

During the period of August 16, 1981, through December 16, 1982, 15-mL blood culture specimens collected at the Seattle Veterans Administration Medical Center (SVAMC) were divided into two aliquots. The first 10-mL aliquot was inoculated directly into aerobic and anaerobic BACTEC (Johnston Laboratories, Towson, MD) vials (DIR); the remaining 5 mL was processed in an resin-containing Antimicrobial Removal Device (Marion Scientific, Kansas City, MO) before transfer to a second, identical set of aerobic and anaerobic vials (ARD). The final volume of inoculated blood from the ARD specimen was half that of the DIR specimen. Both sets of vials were processed using the BACTEC radiometric detection system. One hundred fifty specimen pairs grew 161 significant pathogens; 43 isolates were recovered only from the ARD sample, 39 only from the DIR samples, and 79 from both. Of the 35 isolates recovered from patients receiving anti-microbial agents active against the isolated pathogens, 21 were recovered only from the ARD specimen and 5 only from the DIR specimen (P less than 0.005). Of the 15 S. aureus strains isolated from patients on therapy, 12 were recovered only from the ARD specimen, 2 only from the DIR sample, and 1 from both samples (P less than 0.01). Ten of the 32 isolates of S. aureus recovered from antibiotic-free patients were found only in the ARD specimen and three only in the DIR specimen (P = 0.05). The ARD specimens recovered significantly more S. aureus from all patients regardless of antibiotic status.

Use of the fluorochrome calcofluor white in the screening of stool specimens for spores of microsporidia.

Microsporidia are obligate intracellular protozoal pathogens associated with chronic diarrhea in individuals infected with HIV. Direct detection methods for microsporidial spores in stool include chromotrope-based, fluorochrome, and immunofluorescent stains. The authors compared the ability to detect microsporidial spores in 168 stool specimens using two stains: a chromotrope-based modified trichrome stain and a fluorochrome stain, calcofluor white (Cellufluor, Polysciences, Warrington, PA). In addition to being faster and easier to perform, the calcofluor white stain was found to be more sensitive than the chromotrope-based stain, as 6 of 24 specimens positive by calcofluor white were negative by the chromotrope-based stain on initial smear evaluation. Repeat examination confirmed these six as being positive. To evaluate the specificity of the calcofluor white stain, 20 formalin-fixed stool specimens (5 positive and 15 negative for microsporidial spores) were evaluated in blinded fashion by two affiliated clinical laboratories using their own formulations of calcofluor white. A single discrepant result (falsely positive) was reported from one laboratory. The use of the calcofluor white stain is recommended as a simple and highly sensitive screening procedure for the detection of microsporidial spores in stool specimens.

Evaluation of the FIAX semiautomatic fluorescent immunoassay system for the detection of IgG antibodies to Toxoplasma gondii.

A commercially available solid phase fluoroimmunoassay system (FIAX, International Diagnostic Technology, Santa Clara, CA) was evaluated in parallel with a standard indirect fluorescent-antibody test (IFAT) for the detection of IgG antibodies to Toxoplasma gondii. Titers obtained by the FIAX method on the 101 patient samples correlated well with the standard procedure. Sensitivity of the FIAX system was 96% and specificity was 93%. A method for measuring serum titer reproducibility applicable to both conventional doubling dilution and to automated procedures was employed, allowing a meaningful comparison of precision in the two systems. It was found that titer reproducibility in the FIAX system was better than that of the IFAT and exceeded that expected with most conventional double-dilution serological procedures. The FIAX system will most benefit those laboratories with relatively large numbers of samples which can be batch tested.

Four year prospective evaluation of nosocomial bacteremia: epidemiology, microbiology, and patient outcome.

A prospective study of all patients with clinically significant nosocomial bacteremia at one institution from 1994 to 1997 was performed to: (1) describe the epidemiology and microbiology of nosocomial bacteremias; (2) determine the crude mortality associated with such infections; and (3) identify independent predictors of mortality. Four hundred four episodes of bacteremia occurred in 322 patients; the crude in-hospital mortality was 31%. Coagulase-negative staphylococci, Staphylococcus aureus, and enterococci were the leading pathogens, and intravascular catheters were the most frequently identified source. The highest mortality occurred in patients with candidemia (67%). Independent predictors of mortality included evidence of shock at the time of infection, acquisition of bacteremia in an intensive care unit, a "Do Not Attempt Resuscitation" order, and the presence of certain comorbid conditions (e.g., malignancy, HIV infection). Because many of these infections may be preventable, education of health care providers and strict adherence to established infection control practices are critical.

Evaluation of four mycobacterial blood culture media: BACTEC 13A, Isolator/BACTEC 12B, Isolator/Middlebrook agar, and a biphasic medium.

Four commercially available mycobacterial blood culture systems were compared for sensitivity and time to detection of growth. A 5-ml volume of SPS-anticoagulated blood was cultured in a BACTEC 13A vial and a modified M7H11/BHI biphasic medium. In addition, two aliquots of Isolator concentrates, each derived from 5 ml of blood, were inoculated into a BACTEC 12B vial and onto a pair of Middlebrook 7H11 agar plates (M7H11). Mycobacteria were recovered from 32 of 180 cultured specimens (17.8%). Growth was detected in 30 (93.7%) of the 13A vials, 27 (84.4%) of the M7H11 agar plates, 26 (81.2%) of the 12B vials, and 14 (43.8%) of the biphasic bottles. The mean times to growth detection in the 13A vial (14.2 days) and the 12B vial (13.7 days) were shorter than in either the M7H11 plates (20.8 days) or the biphasic medium (24.1 days). When the Isolator/12B vial-and-M7H11 plates were evaluated as a single system, 29 cultures (90.6%) had a mean time to growth detection of 13.5 days. Colony-forming units per ml were inversely associated with time to growth detection. Delay in transport (greater than 24 h) appeared to reduce viability. The direct inoculation feature makes the 13A vial very suitable for mycobacterial blood cultures.

Four-year prospective evaluation of community-acquired bacteremia: epidemiology, microbiology, and patient outcome.

The objectives of this study were to (1) describe the epidemiology and microbiology of community-acquired bacteremia; (2) determine the crude mortality associated with such infections; and (3) identify independent predictors of mortality. All patients with clinically significant community-acquired bacteremia admitted to a university-affiliated Veterans Affairs medical center from January 1994 through December 1997 were evaluated. During the study period, 387 bacteremic episodes occurred in 334 patients. Staphylococcus aureus, Escherichia coli, and coagulase-negative staphylococci were the most commonly isolated organisms; the most frequent sources were the urinary tract and intravascular catheters. Approximately 14% of patients died. Patient characteristics independently associated with increased mortality included shock (OR 3.7, p = 0.02) and renal failure (OR 4.0, p = 0.003). The risk of death was also higher in those whose source was pneumonia (OR 6.3, p = 0.03) or an intra-abdominal site (OR 10.7, p = 0.02), or if multiple sources were identified (OR 13.4, p = 0.003). Community-acquired bacteremia is often device-related and may be preventable. Strategies that have been successful in preventing nosocomial device-related bacteremia should be adapted to the outpatient setting.

Automated antibiotic susceptibility testing: comparative evaluation of four commercial systems and present state.

Automation of AST has come quite some way and is here to stay. In particular, fully automated, "hands off" instruments have great appeal to laboratories with a limited number of well-trained and experienced clinical microbiology personnel. None of the evaluated instruments is perfect, but then neither are the standard or reference techniques. Overnight incubation has been the yardstick since the early days of in vitro AST. Given the usually shorter therapeutic intervals of 4- to 12-hour dosage schedules, it is quite possible that shorter incubation times for in vitro tests will become more of a standard. Until that time, newer, including automatic, techniques need to be evaluated against the more traditional standard methods. Quality control is critical, and since no systematic approach aside from individual manufacturers' suggestions exists, it should be developed by the NCCLS or similar agencies. Quality control might include standards for the evaluation of such equipment and systems because the development of new technology in this area will continue. Overall, reproducibility and accuracy of the instruments and methods evaluated were quite promising and should encourage well-designed studies of clinical correlation and relevance. The AMS equipment has been in use for routine AST in the clinical laboratories of the Seattle Veterans Administration Medical Center and the University of Washington Hospital. Because of its simplicity and flexibility, the Kirby-Bauer method continues to be an alternate technique for certain important clinical isolates, for instance, blood cultures in both laboratories. Finally, it should be remembered that the most critical function of all such equipment is the reliable detection of resistance.

Bacterial culture specimens. Categories, collection, and interpretation.

An approach to the collection and interpretation of bacterial cultures based on specimen category is presented. The sensitivity and specificity of cultures of material taken from deep closed body areas (category 1), deep communicating body areas (category 2), and superficial body surfaces (category 3) are considered.