Evaluation of routine anaerobic blood cultures in the BacT/Alert blood culture system.

To evaluate the use of routine anaerobic blood cultures with the BacT/Alert system, results of 12,289 blood culture sets collected from adults over a 9-month period were reviewed. Of the sets included in the study, 1,306 (10.6%) from 808 patients grew 1 or more organisms. Anaerobes were present in 39 sets from 38 patients. Of the positive sets, both bottles were positive in 60.7% of cases, the aerobic bottle only in 23.7%, and the anaerobic bottle only in 15.6%. When only the 254 patients who had 2 or more positive sets were considered, both bottles were positive in 71.5% of cases, the aerobic bottle only in 20.7%, and the anaerobic only in 7.8%. In this subset of patients gram-positive bacilli, gram-negative bacilli other than Enterobacteriaceae, and yeasts grew significantly more frequently in aerobic bottle. No organisms preferred the anaerobic bottle. These data support the selective use of the BacT/Alert anaerobic blood culture bottle in patients at risk for anaerobic bacteremia.

Efficacy of cefixime in the treatment of acute otitis media in children.

OBJECTIVE: To compare the efficacy of cefixime with amoxicillin in the treatment of acute otitis media in children. DESIGN: Randomized, nonblinded study. SETTING: General pediatric clinic at a university hospital in Texas. PARTICIPANTS: A volunteer sample of 201 children, aged 2 months through 6 years. INTERVENTIONS: A 10-day oral course of cefixime (8 mg/kg per day administered once daily) or amoxicillin (40 mg/kg per day administered in three divided doses [every 8 hours]). MEASUREMENTS/MAIN RESULTS: Tympanocentesis for bacterial culture was performed on all affected ears on enrollment and after 4 to 6 days of therapy. The patients were evaluated clinically 4 to 6 days after starting therapy, at the end of therapy, and 3 to 4 weeks after therapy was completed. Using Fisher's Exact Test, no significant difference was found between the two treatment groups for rate of clinical improvement or rate of eradication of Haemophilus influenzae and Streptococcus pneumoniae. However, combining the results from this study and two previously reported studies, cefixime was found to be more effective in eradication of H influenzae and less effective in eradication of S pneumoniae.

Office diagnosis of asymptomatic bacteriuria in pregnant women.

Diagnosis and treatment of asymptomatic bacteriuria in pregnant patients can virtually eliminate pyelonephritis, the most common medical cause for antepartum hospitalization. However, the ever-increasing cost of the urine culture has led most clinicians away from routine urine screening. Uricult dip-slide paddles provide an inexpensive, efficient way to screen urine. Clean-catch urine specimens were obtained from 544 consecutive asymptomatic pregnant patients seen in the outpatient obstetric clinic at the Medical University of South Carolina. Specimens were analyzed by both traditional culture techniques and the Uricult dip-slide paddles. By comparison, the Uricult test detected 55 of the 56 significant gram-negative urinary pathogens found by culture. Detection of potential gram-positive pathogens is more difficult. A scheme is proposed that allows reliable, inexpensive surveillance in all pregnant patients. Hopefully, this algorithm will rekindle the obstetrician's interest in urine screening.

Identification of gram-negative bacilli using the Autobac IDX.

The Autobac IDX is a new system for the rapid identification of clinically significant members of the Enterobacteriaceae and Aeromonas, Acinetobacter, Alcaligenes, Flavobacterium, Moraxella, and Pseudomonas species. The use of 18 differentially inhibitory compounds such as dyes and antibiotics along with a computerized algorithm based on a multivariate analysis provides the basis for the identification of 30 different groups of gram-negative bacilli. Required preliminary tests include observations on the presence or absence of swarming on a sheep blood agar plate and noting the following: growth, lactose fermentation, and bile precipitation from a MacConkey plate. Spot indole and spot oxidase tests must be performed as well. Identification by the Autobac IDX System takes 3-6 hr after completion of the preliminary tests. From a total of 403 isolates tested, the Autobac system agreed with the MicroID AND N/F systems on 382 identifications (94.8%). Four isolates, two Acinetobacter anitratus, one Serratia marcescens and one Moraxella osloensis could not be identified by IDX. Additional testing was required on 35 (8.7%) of the isolates.

Acridine orange staining and radiometric detection of microorganisms in blood cultures.

To determine whether acridine orange (AO) staining of blood cultures could be used as a substitute for blind subculture when used in conjunction with the BACTEC system (Johnston Laboratories, Inc., Towson, Md.), the two methods were compared on all BACTEC-negative specimens. Since blind subcultures were routinely performed in our laboratory on days 2 and 6 of incubation, AO staining was also performed on these days. Cultures which were BACTEC positive on day 1 of incubation were not included in the study. Of the 2,395 bottles tested after 2 days of incubation, 106 were subculture positive. Of these, 96 (90.6%) were also AO positive and BACTEC positive, 3 (2.8%) were AO positive and BACTEC negative, and 7 (6.6%) were AO negative and BACTEC positive. Of the 3,487 bottles tested on day 6 of incubation, 14 were subculture positive; 7 (50%) of these were AO positive and BACTEC positive, and seven were AO positive and BACTEC negative. Of the total of 10 culture-positive bottles missed by BACTEC, all were positive, and all 10 companion aerobic bottles were BACTEC positive. In both phases of the experiment, there was a total of only four false-positive AO stains. As a result of this investigation, we have substituted AO staining for blind subculturing of BACTEC-negative bottles.

Evaluation of an automated, computerized system (automicrobic system) for Enterobacteriaceae identification.

The automated and computerized AutoMicrobic system (AMS; Vitek Systems, Inc., subsidiary of McDonnell Douglas, Hazelwood, Mo.) was evaluated as a means of identifying the Enterobacteriaceae. The Micro-ID system (General Diagnostics, Morris Plains, N.J.) and, when necessary, conventional tubed media were used for comparison. Identification by AMS and Micro-ID differed in only 12 of 1,528 isolates (0.8%). Disagreements occurred primarily with Enterobacter spp. Precision testing of the AMS showed only 1 of 72 tests (1.4%) deviating from the expected. The AMS was found to be an accurate and precise method for the identification of Enterobacteriaceae.

A comparison of four commercial systems for the identification of nonfermentative gram-negative bacilli.

Four commercial systems for the identification of glucose nonfermentative, gram-negative bacilli and the conventional system used in our laboratory were compared. The API 20E, Roche Oxi/Ferm Tube, BBL Minitek, Flow N/F System, and our system were compared for accuracy, time needed for identification and number of isolates needing additional testing. A total of 241 different isolates were used. The API 20E identified 86.7% correctly; Oxi/FermTube, 83.0%; Minitek, 93.4%; N/F System, 90.5%; and our system, 90.0%. Within 24 hours after isolation, the API 20E identified 25.7%; Oxi/Ferm Tube and Minitek, 0%; N/F System 27.3%; and our system, 35.7%. After 48 hours, the API 20E identified 74.7%; Oxi/Ferm Tube, 35.7%; Minitek, 45.2%; N/F System, 83.0%; and our system, 94.6%. The number of isolates that required additional testing for identification by the API 20E was 119; Oxi/Ferm Tube, 161; Minitek, 88; N/F System, 43; and our system, 36. Ease of performance, technologist time, and level of identification required by individual laboratories are discussed.

An identification scheme for gram-negative nonfermentative bacilli.

A series of six flow charts have been developed to identify the Gram-negative nonfermentative bacilli most commonly isolated from clinical specimens. Colonial morphology and oxidase reactivity determine the pathway to be followed on the flow chart which then indicates the specific test to be performed. Most isolates can be identified within 24 hours using 3 to 5 tests. Each pathway was selected on the basis of 94-100 per cent confidence limits otherwise an alternate pathway is shown. Results of 2,788 nonfermenters identified by this scheme are discussed.

Interference of human spermatozoal motility and spermatozoal agglutination by Candida albicans.

Human spermatozoa were exposed to concentrations of 10(2) to 10(7) organisms per ml. Candida albicans. A subsequent striking decrease in spermatozoal motility and significant agglutination were observed. The possible role of mycotic genital tract infections in human infertility is considered.

PIP: Candida albicans, isolated from a urine culture, was grown in beef heart infusion containing penicillin and streptomycin. Several 10-fold dilutions were made in physiological saline. Semen ejaculations were obtained from 8 volunteers. Drops of a suspension of semen in various dilutions of Candida albicans culture, or in culture media alone, were immediately observed microscopically for spermicidal motility and agglutination. After 2 and 4 hours of incubation, observations were repeated. On immediate examination spermatozoal motility was observed to decrease as the concentration of Candida albicans was increased. In control samples spermatozoal activity remained normal. The pH of all samples remained between 7-8. Spermatozoal agglutination was not noted immediately but after 2 and 4 hours of incubation clumping was obvious. Infertility may follow as a result of mycotic vaginitis, particularly with a marginal state of fertility. In evaluation of couples for infertility, the presence of clinical or subclinical genital tract infection with these organisms should be considered. Antimycotic treatment may be a simple solution for a seemingly complex problem.

Evaluation of the acid-fast smear.

A retrospective analysis of the data involving all specimens submitted to the mycobacteriology laboratory over the past 20 months supports the continued use of the acid-fast smear as an aid in the detection of tuberculosis.

Evaluation of a dual-staining method for acid-fast bacilli.

A dual-staining procedure for acid-fast bacilli was found to have poor correlation with the Ziehl-Neelsen and auramine-rhodamine staining techniques.

Automatic gram-staining with the microstainer II.

A comparison was made between the Microstainer II, an automatic staining machine, and the traditional, manual gram-staining method using clinical material and known organisms in a double blind study. Gram-reactions were in agreement with 98.4% of the organisms. The machine-stained microorganisms were generally found to be of the same or better quality than manually-stained organisms. Transfer of bacteria from slide to slide or smear to smear was not a significant problem. The Microstainer II would appear to be a useful addition to the large volume bacteriology laboratory.

Bacterial effect on sperm motility.

Human semen containing normal number of sperm was exposed to concentrations of Escherichia coli varying from 500 to 10-8 colonies per cubic centimeter. A significant decrease in motility was abserved at 10-6 colonies per cubic centimeter.

Antibiotic resistance patterns of clinical isolates of Serratia marcescens.

Antimicrobial susceptibility patterns of 102 clinical isolates of Serratia marcescens from three medical centers were studied by using disk sensitivity and agar dilution methods. The least resistance was demonstrated against gentamicin, nalidixic acid, chloramphenicol, and sulfisoxazole, all of which inhibited more than 80% of the strains. Cephalothin was completely ineffective, and more than 90% of strains were resistant to ampicillin and tetracycline. As demonstrated by the agar dilution method, the minimal inhibitory concentration of nalidixic acid, gentamicin, tobramycin, and chloramphenicol for most strains fell within therapeutically attainable concentrations. The prevalence of resistance to ampicillin, cephalothin, and tetracycline was nearly the same at all three medical centers, whereas there appeared to be patterns characteristic for each center with regard to the other drugs used. Eleven of the isolates produced pigment and exhibited patterns similar but not identical to those of the nonpigmented strains, all 11 being resistant to between three and six drugs. Half of the strains were resistant to five or more antibiotics, indicating that some Serratia exhibit resistance to an unusually broad range of therapeutic agents.