Mycobacteria other than Mycobacterium tuberculosis: review of microbiologic and clinical aspects

The rate of isolation of mycobacteria other than Mycobacterium tuberculosis (MOTT) has increased over the past several years; in some areas the isolation rate for Mycobacterium avium-Mycobacterium intracellulare has surpassed that for M. tuberculosis. Simultaneously, the spectrum of clinical manifestations with the various species has widened. Outbreaks of disease due to Mycobacterium chelonae have occurred in renal dialysis patients. New species have been described: Mycobacterium malmoense is primarily a pulmonary pathogen, and Mycobacterium haemophilum has been recovered from cutaneous lesions in immunosuppressed patients. In addition, reports of disease due to species generally considered saprophytic have become more numerous. In this review, the epidemiologic, pathologic, and clinical features of the individual MOTT species are discussed. A brief summary of mycobacteria isolated at the Cleveland Clinic foundation between 1982 and 1985 is also presented.

Can microscopic screening be used to determine the suitability of sputum for culture of Haemophilus species?

Sputum specimens with less than 25 squamous epithelial cells per low-power field were also examined microscopically for the presence of alveolar macrophages and Haemophilus-like organisms and cultured for Haemophilus species. The isolation of Haemophilus species was considered to be clinically significant in 11 of 13 (84.6%) specimens containing greater than or equal to 2+ alveolar macrophages (at least 1 alveolar macrophage/high-power field) and predominant Haemophilus-like organisms (greater than or equal to 12 Haemophilus-like organisms/oil immersion field); in 12 of 27 (44.4%) specimens with greater than 2+ alveolar macrophages and few, if any, Haemophilus-like organisms; and in only 1 of 20 (5%) specimens with few, if any, alveolar macrophages and Haemophilus-like organisms. It was concluded that only sputum specimens with either greater than or equal to 2+ alveolar macrophages or predominant Haemophilus-like organisms or both should be candidates for culture of Haemophilus species.

Antistaphylococcal activity of a cyclic peptide, LY146032, and vancomycin

The inhibitory and bactericidal activities of a novel cyclic peptide antibiotic, LY146032, and vancomycin against oxacillin-susceptible and oxacillin-resistant staphylococci were compared. The MICs for 90% of strains were two- to fourfold higher for vancomycin than for LY146032. MBC/MIC ratios for all strains were less than or equal to 2. In killing rate studies with four strains of staphylococci, there was no detectable growth in the presence of 4X the MIC of either LY146032 or vancomycin after 24 h of incubation.

Lysis-centrifugation blood culture technique. Clinical impact in Staphylococcus aureus bacteremia

To determine the clinical impact of enhanced detection of Staphylococcus aureus by a lysis-centrifugation (LC) blood culture system, consecutive cases of S aureus bacteremia during a seven-month period were reviewed. Of 77 clinically significant cases, the LC system detected 70 cases (91%) while a conventional broth system detected 67 cases (87%). Of 60 cases detected by both systems, the LC system was positive earlier than the broth system by one or more days in 34 cases (57%) and later in none. It also detected more (12 vs four of 13) patients with persistent bacteremia who were receiving antimicrobial treatment. Forty-three patients (56%) did not receive appropriate antimicrobial therapy until cultures were reported positive. Enhanced detection of S aureus bacteremia is a clinically important advantage of the LC blood culture technique.

Blood cultures: issues and controversies

Blood-culture procedures must be designed to overcome the intermittency and low order of magnitude of most bacteremias and fungemias and to inhibit any antimicrobial properties or components of the blood. Among the several variables affecting yields, the volume of blood cultured appears to be most important. It is recommended that at least 10 ml, and preferably 20-30 ml, of blood be obtained for each of two to three separate cultures. More than three separate blood cultures per septic episode is rarely necessary. Other issues involve the systems used for blood culture and the procedures used for their examination.

Lack of antibacterial activity of pentoxifylline

Pentoxifylline was inactive when tested against 70 fresh clinical bacterial isolates, as well as when tested alone and in combination with erythromycin, vancomycin, or rifampin against Escherichia coli PC1349 (wild type) and its heptose-deficient outer membrane mutant E. coli PC2040. No antibacterial activity of pentoxifylline or its metabolites could be detected in sera from patients receiving pentoxifylline or its metabolites could be detected in sera from patients receiving pentoxifylline.

Microbiologic analyses of nasal polyp tissue

Nasal polyps from 40 patients were cultured within 2 1/2 hours after surgical removal to determine whether microorganisms were present. The first 20 polyps were cultured for aerobic and anaerobic bacteria, viruses, fungi, mycoplasmas, and mycobacteria. Of these 20 polyps, eight were sterile by all tests, one grew Cryptococcus albidus, one grew Sporobolomyces, one had large numbers of Peptostreptococcus micros and Propionibacterium acnes, greater than 10(6) colony-forming units per gram (cfu/gm), and nine had aerobic bacteria including 10 different species at levels less than 10(5) cfu/gm. The second 20 polyps were cultured for aerobic bacteria only; 11 polyps were positive. Overall, 14 of 26 polyps from patients with asthma and two of 14 polyps from patients without asthma were positive for aerobic bacteria at levels greater than 10(3) cfu/gm (p less than 0.05). Multiple aerobic bacterial species tended to occur in polyps from patients with asthma (11 of 26) more frequently than in those from patients without asthma (one of 14) (p less than 0.01). There was a highly significant positive correlation between tissue neutrophilia and bacterial count (r = +0.9; p less than 0.001). The results indicate that patients with asthma have a significantly higher number and a tendency to a greater variety of aerobic bacteria in nasal polyp tissue than patients without asthma and that the number of infiltrating neutrophils is directly related to the number of bacteria.

Clinical-histologic-microbiologic analysis of 419 lymph node biopsy specimens

The results of culture and histopathologic examination of 419 lymph node biopsy specimens obtained from 414 patients in 1978-1983 were correlated with clinical histories. The clinical diagnosis was lymphadenopathy of unknown etiology in 113 cases, sarcoidosis in 93, malignant lymphoma in 86, metastatic carcinoma in 17, histoplasmosis in 18, tuberculosis in 13, and other miscellaneous conditions in 79. All but two clinically significant microbial isolates from lymph nodes were either mycobacteria or fungi: the only exceptions were staphylococcal isolates from two children with lymphadenitis. Of 66 lymph nodes associated with bacterial, mycobacterial, or fungal disease, 48 included granulomatous and/or acute inflammatory lesions. Of 33 lymph nodes that were culture-positive, two had histologic evidence of lymphoid hyperplasia, and the remainder included granulomatous and/or acute inflammatory lesions. With one exception, lymph node cultures in immunocompetent patients were positive only when there was a granuloma and/or an acute inflammatory lesion in the tissue. On the basis of these findings, it was concluded that lymph nodes from immunocompetent patients should be cultured only when a granuloma and/or an acute inflammatory lesion are detected and that the cultures can be limited to mycobacteria and fungi.

In vitro activity of an orally administered cephalosporin, LY164846, against potentially pathogenic respiratory and dermal bacterial isolates

The antibacterial activity of LY164846, a new orally administered semisynthetic cephalosporin, was compared with that of amoxicillin-clavulanic acid against 492 potentially pathogenic respiratory tract and dermal isolates. Against groups A, B, and G streptococci; pneumococci; staphylococci (other than methicillin resistant); Haemophilus influenzae; Branhamella catarrhalis; and meningococci, the MICs for 90% of strains tested of LY164846 and amoxicillin-clavulanic acid were less than or equal to 4 and less than or equal to 1 microgram/ml, respectively. LY164846 was equally active against beta-lactamase-positive and -negative strains of Haemophilus and Staphylococcus. MBC to MIC ratios of LY164846 versus H. influenzae were less than or equal to 2, while those with Staphylococcus aureus were more difficult to determine because of skipped tubes or paradoxic effects. There were minimal inoculum, pH, or serum effects on LY164846 activity against H. influenzae and S. aureus. In time-kill studies, LY164846 and amoxicillin-clavulanic acid at double MICs were 99.9 to 100% bactericidal to H. influenzae in 24 h; two times the MIC of LY164846 and four times the MIC of cephalexin were 99.9 to 100% bactericidal to S. aureus in 24 h. Based on error-rate-bounded analysis, the following interpretative guidelines for 30-micrograms LY164846 disk diffusion test diameters are suggested: greater than or equal to 19 mm, susceptible (MIC, less than or equal to 4 micrograms/ml); 16 to 18 mm, intermediate (MIC, greater than 4 but less than or equal to 8 micrograms/ml); less than or equal to 15 mm, resistant (MIC, greater than 8 micrograms/ml).

The clinical significance of stool isolates of aeromonas

The purpose of this study was to determine the clinical significance of different Aeromonas species isolated from stool. During a 17-month period, 29 strains of Aeromonas were isolated and identified to species with the following results: 22, A. caviae, 5, A. hydrophila, and 2, A. sobria. Clinical significance was determined independently of knowledge of speciation result. Nineteen isolates represented colonization, implying that Aeromonas can be recovered from the gastrointestinal tract without causing primary disease. The remaining 10 isolates were of indeterminate significance and may have played a role in infection, but pertinent tests to rule out other enteric pathogens had not been done. A correlation between species and clinical significance could not be established. Antimicrobial susceptibility testing was performed on the 29 isolates. A. caviae showed an unexpected resistance to cefazolin and cefoxitin, whereas representatives of all three species displayed resistance to trimethoprim/sulfamethoxazole.

Phencyclidine (PCP) abuse. A close-up look at a growing problem

PCP or "angel dust" is a dissociative anesthetic agent with notoriety as an abuse substance. Numerous members of many subcultures are frequent users of this drug. It is well known in California's psychedelia, along the East Coast, and in the middle- and working-class suburbs of the Midwest. It is important that practitioners become acquainted with the drug and its effects. Persons intoxicated with PCP have murdered their own children and have even jumped out of high-rise apartment buildings. States of florid psychosis lasting for days can follow a brief encounter with PCP. Inadvertent administration of narcotics and barbiturates to patients with acute PCP intoxication can lead to a crisis that could prove to be fatal.

Beta-hemolytic group F streptococcal bacteremia: a study and review of the literature

Group F streptococci are part of the oropharyngeal, bowel, and perineal flora. Abscess formation by these organisms most commonly involves the cutaneous system: the next most common sites, in descending order, are the cervicofacial, dental, and intraabdominal areas. Among our population of patients with abscesses, serious infection rarely occurred in otherwise healthy individuals in the absence of trauma. Group F streptococci represented 2% of beta-hemolytic streptococcal isolates from all patients with bacteremia who were hospitalized at Mayo Clinic-affiliated hospitals from 1970 to 1980. In five of seven bacteremic patients, some manipulation, perforation, or underlying pathology associated with the gastrointestinal tract existed. Polymicrobial bacteremia was common. All isolates of group F streptococci were susceptible to less than or equal to 0.1 microgram of penicillin/ml.

The clinical microbiology laboratory. Utilization and cost-effectiveness

Utilization of the microbiology laboratory is subject to limitations posed by the diversity of microbial agents causing infection, multiple and often poorly accessible sites of infection, contamination of specimens with indigenous flora, and failure of communication between clinician and microbiologist. Cost constraints increasingly limit the extent of microbiologic services available on-site and lead to decentralization of laboratory services and possible loss of quality control. Increased attention is being paid to process control of cultures, rapid screening and diagnostic tests as culture substitutes, and limitations on antibiotic susceptibility testing.

Evaluation of a rapid identification method for Neisseria spp

A comparison was made of carbohydrate degradation reactions of Neisseria gonorrhoeae, Neisseria meningitidis, Neisseria lactamica, Neisseria mucosa, Neisseria sicca, Neisseria subflava, and Branhamella catarrhalis in a rapid (0.5- to 1-h) identification micromethod (RIM-N Kit; Austin Biological Laboratories, Inc., Austin, Tex.) and in a serum-free agar slanted medium (72 h). Reactions after 1 h in the RIM-N system agreed completely with those after 72 h in the conventional system.

Ciprofloxacin disk susceptibility tests: interpretive zone size standards for 5-microgram disks

Evaluations of 5-microgram ciprofloxacin disk diffusion susceptibility tests were performed independently by seven different investigators. The results of the separate tests were combined to increase the number of resistant strains in the challenge set of microorganisms. Based on data with 2,652 isolates, the following interpretive breakpoints are tentatively proposed for use in ongoing clinical trials of ciprofloxacin: less than or equal to 15 mm, resistant (MIC greater than 2.0 micrograms/ml); 16 to 20 mm, intermediate (1.0 less than MIC less than or equal to 2.0 micrograms/ml); and greater than or equal to 21 mm, susceptible (MIC less than or equal to 1.0 micrograms/ml). Disk tests with Streptococcus spp. and with Pseudomonas maltophilia were not reliable; other microorganisms were accurately categorized by the disk diffusion test.

Antistreptococcal activity of Sch 34343, a new penem antibiotic

The in-vitro activity of Sch 34343 was compared with that of penicillin and cefotaxime against clinical isolates of streptococci. Sch 34343 was highly active against Streptococcus pneumoniae, viridans streptococci, streptococci of groups A, B, C and G, and Str. bovis. Ninety per cent of these strains were inhibited by less than or equal to 0.25, less than or equal to 0.12 and less than or equal to 0.06 mg/l of Sch 34343, penicillin and cefotaxime respectively. Activity of Sch 34343 against Str. faecalis was only moderate. Sch 34343 had very good bactericidal activity against group B streptococci, and showed high MBC/MIC ratios against penicillin-tolerant viridans streptococci and Str. faecalis. Sch 34343, 20 mg/l, and gentamicin, 4 mg/l, were synergistic against both of the penicillin-tolerant viridans streptococci, and one-third of the Str. faecalis strains.

Erythromycin: a microbial and clinical perspective after 30 years of clinical use (2)

Erythromycin, first introduced for clinical use 30 years ago, was found to be effective for the treatment of gram-positive bacterial infections. Emergence of resistance and the advent of penicillinase-resistant penicillins limited the use of erythromycin for serious staphylococcal infections; however, erythromycin remains among the drugs of choice for the treatment of acne, infections of the skin and soft tissues, streptococcal pharyngitis, bronchitis, pneumonitis, diphtheria, carriers of pertussis, and, when administered with a sulfonamide, otitis media. Erythromycin is the drug of choice for the empiric treatment of outpatients with pneumonitis. Erythromycin is also the drug of choice for the treatment of Legionella pneumonia and is effective therapy for Chlamydia infections. Other uses of erythromycin include prophylaxis for elective colon operations and treatment of Campylobacter enteritis, genitourinary infections, and some sexually transmitted diseases.

Erythromycin: a microbial and clinical perspective after 30 years of clinical use (1)

Erythromycin is a macrolide that acts by inhibiting the translocation reaction during protein synthesis. Erythromycin is inactive against the Enterobacteriaceae and Pseudomonas aeruginosa except under alkaline conditions. Erythromycin is active against most gram-positive bacteria; some gram-negative bacteria, including Neisseria, Bordetella, Brucella, Campylobacter, and Legionella; and Treponema, Chlamydia, and Mycoplasma. The emergence of resistance to erythromycin is closely associated with its use and is often plasmid mediated. After its oral or parenteral administration, erythromycin diffuses readily into intracellular fluids and is actively concentrated intracellularly by polymorphonuclear leukocytes and alveolar macrophages.

An evaluation of a leukocyte esterase/nitrite test strip and a bioluminescence assay for detection of bacteriuria

A leukocyte esterase/nitrite (Chemstrip LNTM) and a bioluminescence assay (LumacTM) were evaluated for detection of bacteriuria in 1,000 urine specimens. Both devices provided high predictive negative values (95.4-97.8%); however, false-negative values at levels of bacteriuria greater than or equal to 10(4) CFU/ml were 22.6% and 12.3%, respectively, for the leukocyte esterase/nitrate and the bioluminescence assay tests. The corresponding false-negative values at levels of bacteriuria of greater than or equal to 10(5) CFU/ml were 16.5% and 3.9%, respectively.

Evaluation of the Quantum II Microbiology System for bacterial identification

The Quantum II Microbiology System correctly identified 250 (89.6%) of 279 gram-negative bacilli from clinical specimens. There were 13 (4.7%) errors in genus identification and 7 (2.5%) errors in species identification; another nine (3.2%) isolates yielded biochemical reaction patterns which were not in the file of the system. Total test time per isolate, excluding inoculum preparation and incubation, was ca. 1.5 min.

Synergy of imipenem or penicillin G and aminoglycosides against enterococci isolated from patients with infective endocarditis

We tested the synergistic activity of imipenem (formerly imipemide, N-formimidoyl thienamycin, or MK 0787) (20 micrograms/ml) or penicillin (20 micrograms/ml) in combination with increasing concentrations of either streptomycin (5, 10, and 20 micrograms/ml) against 13 strains of streptomycin-susceptible enterococci or gentamicin (1, 3, and 5 micrograms/ml) against 13 strains of streptomycin-susceptible enterococci and 7 strains of streptomycin-resistant enterococci. At 24 h, penicillin together with each increment in streptomycin concentration resulted in a significant increase (P less than 0.001) in killing of streptomycin-susceptible enterococci compared with imipenem and the corresponding concentration of streptomycin. Similarly, at 24 h, the magnitude of killing of streptomycin-susceptible enterococci by a combination of penicillin plus each increment of gentamicin concentration was significantly greater (P less than 0.001) than that of the combination of imipenem and the corresponding concentration of gentamicin. Against streptomycin-resistant enterococci, penicillin together with each increment of gentamicin concentration killed significantly more enterococci (P less than 0.02) than did the combination of imipenem and the corresponding concentration of gentamicin. When combined with an aminoglycoside, the synergistic activity in vitro against enterococci of imipenem was significantly less than that of penicillin.

Evaluation of a rapid latex agglutination test for identification of group D streptococci

The SeroSTAT latex agglutination test (Scott Laboratories, Inc., Fiskesville, R.I.) for identification of group D streptococci was compared with bile-esculin agar and Lancefield grouping by using 110 clinical isolates of group D streptococci (S. faecalis, 74; S. bovis, 24; S. durans, 3; S. faecium, 9) and 65 viridans streptococci (S. anginosus-constellatus, 2; Streptococcus MG, 15; S. sanguis II, 14; S. mitis, 7; S. mutans, 5; S. salivarius, 8; S. sanguis I, 8; S. acidominimus, 1; S. morbillorum, 2; S. pneumoniae, 3). All strains of group D streptococci were bile-esculin positive. SeroSTAT reactions were falsely positive with 2 strains of S. sanguisII and 1 strain of Streptococcus MG (4.6% of all viridans streptococci tested) and falsely negative with 10 S. bovis, 8 S. faecalis, 1 S. durans, and 6 S. faecium strains (22.7% of all group D streptococci tested). When considered with colonial morphology and hemolytic reaction, SeroSTAT is a rapid (60-s) and useful test for recognition of group D streptococci.

Evaluation of the Pneumoslide latex agglutination test for identification of Streptococcus pneumoniae

The Pneumoslide latex agglutination tests was evaluated with 106 strains of Streptococcus pneumoniae and 56 strains representing seven species of viridans streptococci. The Pneumoslide test gave one false-positive and one false-negative reaction. Testing of isolated colonies for solubility in 10% sodium deoxycholate was as accurate but was simpler and less expensive to perform.

Comparison of lysis-centrifugation with a biphasic blood culture medium for the recovery of aerobic and facultatively anaerobic bacteria

The Du Pont Isolator tube and Roche Septi-Chek blood culture bottle employ solid media which facilitate the removal of bacteria from static or cidal substances in blood to increase recovery and decrease detection time. In a comparison of 11,567 blood culture sets, the Isolator tube and vented Roche Septi-Chek bottle were positive for 533 (80%) and 494 (74%) of the aerobic and facultatively anaerobic organisms recovered, respectively. This difference was not significant. A significant difference was found in the overall detection time. The Isolator tube recovered the bacteria ca. 1 day earlier. The earlier detection time was most notable with Staphylococcus aureus, viridans streptococci, and Pseudomonas aeruginosa. Among the 355 bacteremic episodes analyzed by a computer program, the Isolator tube was responsible more often for the first report of bacteremia in a given patient. Both systems performed well for the recovery of aerobic and facultatively anaerobic bacteria, but it is recommended that either be used in combination with an unvented broth-containing bottle.