Microbiologic evaluation of cutaneous cellulitis in adults.

Fifty patients with cellulitis were evaluated prospectively using cultures of aspirates from the advancing edge of cellulitis, skin biopsy specimens, and blood. Potential microbial pathogens were isolated in 13 patients. Biopsy specimen cultures were positive in ten patients, while aspirate and blood cultures were positive in five and two, respectively. Aspirate, biopsy, or blood cultures were more often positive in patients with apparent primary lesions than in patients without such lesions. Apparent primary sites of infection were identified and cultured in 24 patients. beta-Hemolytic streptococci were isolated from 17 primary lesions, and coagulase-positive staphylococci were present in 13. Both organisms were isolated from ten primary lesions. Among patients with positive aspirate, biopsy, and/or blood cultures, the same pathogens were also isolated from primary sites in ten of ten patients. Clinical features, including temperature, white blood cell count, and erythrocyte sedimentation rate, were not predictive of positive aspirate, biopsy, or blood cultures. These cultures provided no microbiologic information that was not obtainable from culture of primary lesions.

Central venous catheter-related bacteremia due to Tsukamurella species in the immunocompromised host: a case series and review of the literature.

We report 6 cases of bacteremia due to Tsukamurella species, all of which were in immunosuppressed patients with indwelling central venous catheters (CVCs). Fewer than 20 cases of serious illness due to these gram-positive bacilli have been reported in the medical literature; these cases have mostly been ascribed to the species Tsukamurella paurometabola. Tsukamurella species are frequently misidentified as Rhodococcus or Corynebacterium species. We used high-performance liquid chromatography to identify these organisms to the genus level and 16S ribosomal RNA gene sequencing and DNA-DNA dot blots for species identification. Three of our isolates were identified as Tsukamurella pulmonis, 1 was identified as Tsukamurella tyrosinosolvans, and 1 was identified as a unique species. One isolate was not maintained long enough for species identification. All patients were successfully treated with antimicrobial therapy and CVC removal. Infection with this organism should be considered in the immunosuppressed patient with an indwelling CVC and gram-positive bacilli in the blood.

Hand infections. Bacteriology and treatment: a prospective study.

In a prospective, double-blind study, 193 patients hospitalized for established hand infections were randomized to receive either cefamandole intravenously followed by cephalexin by mouth or methicillin intravenously followed by dicloxacillin by mouth. Careful aerobic and anaerobic cultures were performed. Multiple organisms grew in cultures from 84% of the patients (over three isolates per infection on average). Human bite wounds contained anaerobes 43% of the time compared with 12% for other wounds. The majority of wounds (72%) required operative treatment. In 128 patients assessable for treatment outcome, results were unsatisfactory in 11 (9%). There was no difference in outcome between cefamandole (6/59, 10%) and methicillin (5/59, 8%). The presence of anaerobes, Eikenella corrodens, human bites, or an increasing number of organisms was associated with an unsatisfactory response. The presence of Staphylococcus aureus and/or beta-hemolytic streptococci was associated with a favorable response. The incidence of antibiotic-resistant isolates did not correlate with outcome.

Stratified outcome comparison of clindamycin-gentamicin vs chloramphenicol-gentamicin for treatment of intra-abdominal sepsis.

A randomized, prospective trial was conducted of 93 patients with operatively confirmed intra-abdominal sepsis. The study compared clindamycin-gentamicin and chloramphenicol-gentamicin for treatment of carefully stratified patient groups. Malnutrition, age over 65 years, shock, alcoholism, gastrointestinal tract bleeding, steroid administration, diabetes, obesity, and organ malfunction were present with equal frequencies in each group. The duration of antibiotic treatment averaged 8 1/2 days, and the average length of postoperative hospitalization was 29 days. Study antibiotics were changed for bacteriologic reasons in 11 patients taking clindamycin-gentamicin and 12 patients taking chloramphenicol-gentamicin (25% of the total), and two patients in the clindamycin-gentamicin group had a minor adverse reaction. Initial satisfactory clinical responses were obtained in 59 (63%) patients. Twenty-five patients (27%) subsequently developed unsatisfactory courses, but 48 (52%) patients remained well through the 30-day period. Septic-related mortality occurred in 18 (19%) patients, and two (2%) patients had unrelated deaths. There were no significant differences between the study regimens by the outcome criteria evaluated.

Corynebacterium pseudodiphtheriticum pneumonia in an immunologically intact host.

Corynebacterium pseudodiphtheriticum, a gram-positive bacillus commonly found in the human oropharynx, has been reported as a rare cause of infection in compromised hosts. We report herein a case of lower respiratory tract infection with Corynebacterium pseudodiphtheriticum in a previously healthy 29-yr-old trauma victim. The organism was the predominant bacterial isolate from two endotracheal aspirates and a specific humoral response was demonstrated by enzyme-linked immunosorbent assay.

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.

Success of DNA fingerprinting after failure of biotyping, antimicrobial susceptibility testing, and plasmid analysis to reveal clonality of multiple blood and urine isolates from a patient with Escherichia coli urosepsis.

Multiple isolates of Escherichia coli from the blood and urine of a 60-year-old woman with acute pyelonephritis exhibited different biotypes, antimicrobial susceptibility patterns, and plasmid profiles, suggesting the presence of polymicrobial bacteriuria and leaving in question the origin of the bacteremia. Only after bacterial restriction endonuclease analysis of total bacterial DNA was it discovered that all isolates represented the same strain, with plasmid instability possibly accounting for the varied antimicrobial susceptibility patterns observed. We conclude that the biotype, antimicrobial susceptibility profile, and plasmid profile are sometimes inadequate to clarify the relationships between different clinical isolates of E. coli from a single patient and can lead to erroneous epidemiologic conclusions. DNA fingerprinting can resolve dilemmas these less precise techniques leave unresolved.

Contamination of a multiple-use suction catheter in a closed-circuit system compared to contamination of a disposable, single-use suction catheter.

UNLABELLED: Multiple-use (M-U) closed-system endotracheal suction catheters are effective in preventing arterial oxygen desaturation in patients on positive end-expiratory pressure (PEEP) and may lessen the frequency of bradycardia and hypotension in unstable patients who are prone to these complications of suctioning. However, because M-U catheters remain attached to the ventilator circuit and are reintroduced repeatedly into the patient's airway over 24 hours or longer, they could become heavily contaminated with pathogens. We hypothesized a risk of autocontamination to the patient by re-inoculation of the respiratory tract with organisms that flourished on the M-U catheter while it was isolated from the patient's immune defenses or antibiotic therapy. METHODS: We tested this hypothesis in 30 mechanically ventilated adult patients with positive sputum cultures. We measured and compared the amount of bacteria present on an M-U catheter at the end of a 24-hour use period, the amount of bacteria present in the patient's sputum at that time, and the amount of bacteria present on a single-use (S-U) catheter at that time, after it had made one pass into the patient's airway. Organisms recovered and colony counts were also compared to results of a sputum culture obtained before the study began. RESULTS: Fourteen different pathogens or potential pathogens were recovered, in numbers of 2 x 10(1) to 2 x 10(7)colony-forming units. The greatest number of colonies was most often recovered from the sputum specimen, and statistical analysis showed no differences in rate or magnitude of contamination between M-U and S-U catheters.(ABSTRACT TRUNCATED AT 250 WORDS)

Coryneform bacteria in infectious diseases: clinical and laboratory aspects.

Coryneform isolates from clinical specimens frequently cannot be identified by either reference laboratories or research laboratories. Many of these organisms are skin flora that belong to a large number of taxonomic groups, only 40% of which are in the genus Corynebacterium. This review provides an update on clinical presentations, microbiological features, and pathogenic mechanisms of infections with nondiphtheria Corynebacterium species and other pleomorphic gram-positive rods. The early literature is also reviewed for a few coryneforms, especially those whose roles as pathogens are controversial. Recognition of newly emerging opportunistic coryneforms is dependent on sound identification schemes which cannot be developed until cell wall analyses and nucleic acid studies have defined the taxonomic groups and all of the reference strains within each taxon have been shown by molecular methods to be authentic members. Only then can reliable batteries of biochemical tests be selected for distinguishing each taxon.

Improved detection times for Mycobacterium avium complex and Mycobacterium tuberculosis with the BACTEC radiometric system.

A total of 2,559 routine clinical specimens were cultured for mycobacteria by using BACTEC Middlebrook 7H12 medium (BACTEC), Lowenstein-Jensen slants (LJ), and Mycobactosel selective Middlebrook 7H11 slants (M7H11). Thirty-three isolates (1.3%) of M. avium complex and 82 isolates (3.2%) of M. tuberculosis were recovered. The BACTEC mean detection time of M. avium complex from 27 smear-negative specimens was earlier than that of conventional media for both decontaminated respiratory specimens (BACTEC, 12 days; LJ, 32 days; and M7H11, 38 days) and untreated tissue and fluid specimens (BACTEC, 8 days; LJ, 30 days; and M7H11, 31 days). The sensitivity for smear-negative M. avium complex with BACTEC (74%) was comparable to that with LJ (74%) and M7H11 (63%). The mean detection times of M. tuberculosis from 56 smear-positive respiratory specimens were 8 days for BACTEC, 16 days for LJ, and 17 days for M7H11, and sensitivities for the detection of positive cultures were 98% for BACTEC, 76% for LJ, and 79% for M7H11. The BACTEC mean detection time of M. tuberculosis in smear-negative specimens was better for tissues and fluids (14 days) than for respiratory specimens (24 days). BACTEC yielded substantially earlier detection of M. avium complex from all specimen types and of M. tuberculosis from smear-positive respiratory specimens. The rapid identification and susceptibility testing of M. tuberculosis in BACTEC agreed completely with conventional tests and provided a 3-week reduction in median time to final reports.

Genetic analysis of drug resistance in Neisseria gonorrhoeae: identification and linkage relationships of loci controlling drug resistance.

The genetic basis of multiple drug resistance of Neisseria gonorrhoeae was investigated by the technique of transformation. Six different genetic loci were characterized by the type and amount of antibiotic resistance they controlled, and also by the degree of linkage to other resistance markers. A streptomycin resistance locus is linked to separate loci determining resistance to tetracycline, chloramphenicol, and erythromycin. A multiple resistance locus was identified. This genetic locus determines resistance to a variety of antibacterial agents. Lastly, a locus determining resistance to the penicillins was found which is unlinked to any other resistance locus.

Prosthetic valve endocarditis caused by Corynebacterium afermentans subsp. lipophilum (CDC coryneform group ANF-1).

Corynebacteria are important causes of endocarditis in individuals with valvular prostheses. We report the first published case of prosthetic valve endocarditis caused by the newly defined species Corynebacterium afermentans subsp. lipophilum (former CDC coryneform group ANF-1). The isolate was recovered from a perivalvular abscess specimen and 5 of 15 Bactec blood cultures after 7 to 15 days of incubation. The isolation, identification, and susceptibility testing of Corynebacterium species are discussed.

Standardized BACTEC method to measure clarithromycin susceptibility of Mycobacterium genavense.

A standardized clarithromycin susceptibility test for Mycobacterium genavense is reported. The BACTEC radiometric broth dilution test method recommended for Mycobacterium avium complex was modified to develop a reliable and reproducible procedure. Test development involved optimization of medium pH and inoculum densities for antibiotic vials as well as growth control vials. MIC control organisms included Mycobacterium simiae, Mycobacterium avium, and Mycobacterium xenopi. Growth control vials required two to three inoculum dilutions, which varied for each species. Clarithromycin MICs and MBCs for 12 isolates and 1 colonial variant of M. genavense ranged from < or = 0.06 to 0.25 microg/ml.

Mycobacterium genavense sp. nov.

Strains of a suggested novel type of mycobacterium have been repeatedly isolated from patients with AIDS. We summarize the results of tests performed to determine enzymatic activities and metabolic properties, the results of fatty acid analyses, and the results of a comparative 16S rRNA sequence determination. We propose formally that this organism represents a new species, Mycobacterium genavense. The type strain is strain 2289, a culture of which has been deposited in the American Type Culture Collection as strain ATCC 51234.

Pursuit of the Corynebacterium striatum type strain.

The description of Corynebacterium striatum (Chester 1901) Eberson 1918AL in Bergey's Manual of Systematic Bacteriology has many inconsistencies with the identification scheme from the Centers for Disease Control and Prevention. We have studied the four C. striatum reference strains available from the American Type Culture Collection and the National Collection of Type Cultures and found that they fit the Centers for Disease Control and Prevention description of this species. However, it appears that the wrong strains were deposited for this species, because none of the reference strains fits the descriptions in the original publications. This is a substantial case for declaring it a nomen dubium, but the name could be rescued if a careful search reveals a strain that was used in making the original description. It is hoped that some readers may have the missing strains labeled with the early names Bacillus striatus, Bacillus flavidus, or Corynebacterium flavidum.

Whole chromosomal DNA probes for rapid identification of Mycobacterium tuberculosis and Mycobacterium avium complex.

Whole chromosomal DNA probes were used to identify clinical isolates of Mycobacterium tuberculosis, Mycobacterium avium complex, and Mycobacterium gordonae. The probe for M. tuberculosis was prepared from Mycobacterium bovis BCG, which has been shown to be closely related to M. tuberculosis. A probe for the M. avium complex was prepared from three strains representing each of the three DNA homology groups in the M. avium complex. The probes were used in dot blot assays to identify clinical isolates of mycobacteria. The dot blot test correctly identified 57 of the 61 (93%) cultures grown on solid media, and 100% of antibiotic-treated broth-grown cells were correctly identified. Identification by dot blot required a maximum of 48 h. When the probes were tested against 63 positive BACTEC (Johnston Laboratories, Inc., Towson, Md.) cultures of clinical specimens, 59% were correctly identified. However, of the 14 BACTEC cultures that had been treated with antibiotics before being lysed, 13 (93%) were correctly identified.

Comparison of quantitative and semiquantitative culture techniques for burn biopsy.

Accurate evaluation of bacterial colonization as a predictive index for wound sepsis has relied on a quantitative culture technique that provides exact colony counts per gram of tissue by culture of five serial dilutions of biopsy tissue homogenate. The method, while useful to the physician, is both labor intensive and expensive. In this study 78 eschar biopsies were cultured by a semiquantitative technique that involved the use of 0.1- and 0.01-ml samples of inocula and by the serial dilution method. Exact colony counts from the semiquantitative culture method were available only from cultures containing 10(4) to 10(6) CFU/g of tissue. Other colony counts were reported as less than 10(4) or greater than 10(6) CFU/g. Agreement by category of colony counts between the two methods was 96%. For prediction of wound sepsis, the semiquantitative procedure had a positive predictive value of 100% and a negative predictive value of 93.7%. This method also resulted in an approximately 30% reduction of work units (as defined by the College of American Pathologists) and a 60% reduction in the amount of media for specimen processing. Therefore, this semiquantitative culture technique provides accurate information to the physician while saving both time and materials.