Biomedical subjects
Publications and source records attributed to M Salfinger.
Increasing interest is being shown in the antituberculous drug pyrazinamide. An in-vitro model using cultures of human blood macrophages was tested with 8 different Mycobacterium tuberculosis trains. A good correlation was found between the susceptibility of the strains to pyrazinamide and the Kinetics in the macrophage culture.
In clinical microbiology, gas-liquid chromatography (GLC) is used mainly for the following applications: (1) demonstration of microbial metabolites in cultures: studies of short-chain fatty acids (chain length 2 to 6 carbon atoms) and of the non-volatile lactic and succinic acids are the basis of taxonomy of obligate anaerobes on the genus level. Demonstration of these compounds in spent culture media is also used for identification of anaerobic bacteria in the clinical laboratory. (2) Investigation of long-chain fatty acids of cell membranes and the cell wall: analysis of fatty acids with chain lengths of 9 to 20 carbon atoms are used primarily for taxonomic purposes. A practical application for use in clinical bacteriology is the Microbial Identification System (MIS) based on equipment built by Hewlett-Packard. Although this system is excellently suited for quantitative analysis of long chain fatty acids and gives valuable preliminary or confirmative information, it often requires additional testing for identification of bacteria to species level. (3) Direct rapid diagnosis of infection: demonstration of metabolic products in body fluids can be of value in infections with anaerobes (demonstration of fatty acids) and yeasts (sugars). GLC combined with mass spectrometry or frequency-pulsed electron capture GLC techniques have been applied to studies of sera, fecal specimens, and cerebrospinal fluids. These latter applications are still in an experimental stage. However, the rapid diagnosis of tuberculosis directly from cerebrospinal fluid and sputum is well advanced. The potential of direct diagnosis without the resort to cultures warrants continued research with these techniques.
Pyrazinamide (PZA) is believed to be mycobactericidal in vivo. Because it is ineffective at neutral pH in vitro, it is thought to owe its in vivo activity at least partly to acting upon tubercle bacilli (TB) in the helpfully low pH of macrophage (MP) phagolysosomes. However, when it was tested in TB-infected cultured human MP, it was not bactericidal and was able only to slow intra-MP bacillary growth. Recent evidence has suggested that human MP need hormonal support from certain vitamin D metabolites to resist TB. This support was not provided in the culture medium of the earlier experiments in which the PZA was relatively ineffective. Here, PZA has been retested in MP cultured in medium supplemented with the hormonally active metabolite of vitamin D, 1,25(OH)2-vitamin D3 (1,25D3). The MP were infected with virulent TB and incubated in various concentrations of PZA. 1,25D3 was added to postinfection medium at 4 micrograms/ml. Inhibition or killing of intracellular TB was quantitated by counts of culturable TB from samples of lysed MP taken at zero, 4, and 7 days after MP infection. Previous evidence for the protectiveness of 1,25D3 alone for human MP against TB was confirmed. The weak inhibition of TB in MP by PZA alone also was confirmed. The two used together synergized to decrease concentrations of PZA which were inhibitory and to switch the action of PZA from weakly inhibitory to bacteriostatic or mildly bactericidal. 1,25D3 had no direct anti-TB effect, and it did not synergize with PZA in the absence of MP, as determined with acidified bacteriologic culture medium in the BACTEC radiometric system.(ABSTRACT TRUNCATED AT 250 WORDS)
1500 sputum specimens and bronchial washings were cultured for mycobacteria. One half of the specimen was treated with N-acetyl-L-cysteine--sodium hydroxide (3%) (NALC) and the other with sodium dodecyl (lauryl) sulfate--sodium hydroxide (1%) (SDS). The different species of contaminants found with each pretreatment method with the BACTEC radiometric system were identified. Contamination occurred in 6% by using SDS and in 10% by using NALC. The SDS method was more effective against Bacillus ssp. and Streptomyces ssp., the major contaminants. However, the growth of Pseudomonas ssp. was a problem in both methods.
The susceptibility of 11 clinical isolates of Mycobacterium tuberculosis, 3 M. kansasii, 3 M. xenopi, 2 M. scrofulaceum, 2 M. marinum, 2 M. malmoense to fleroxacin, ciprofloxacin, norfloxacin, rifampicin, isoniazid, ethambutol, and streptomycin was determined by the standard proportion method (Middlebrook 7H10 agar). All M. tuberculosis, M. kansasii, M. xenopi, M. scrofulaceum, M. marinum, and M, malmoense isolates including those resistant to conventional antimycobacterials were inhibited by 0.5 mg/l of fleroxacin and ciprofloxacin, the lowest tested concentration. Fleroxacin and ciprofloxacin along with ofloxacin, pefloxacin, ansamycin, clofazimine and cycloserine were also tested against 14 isolates of the M. avium complex. Nine of 14 strains (64%) of the M. avium complex were found susceptible to 4 mg/l of fleroxacin and a similar percentage to the other quinolones. On the basis of its in-vitro potency and its favourable pharmacokinetic properties fleroxacin appears to be sufficiently active to warrant further experimental trials against difficult to treat mycobacteria.
The MICs of pyrazinamide (PZA) were determined for Mycobacterium tuberculosis cultivated under different pH conditions in 7H12 liquid medium. Mycobacterial growth was monitored by the radiometric method (BACTEC system; Johnston Laboratories, Inc., Towson, Md.). We observed a predictable eightfold difference between the MICs determined at pH 5.5 and those determined at pH 5.95. The highest MICs for 21 susceptible strains were 50.0 micrograms/ml at pH 5.5 and 400 micrograms/ml at pH 5.95. This eightfold difference enabled us to predict MICs at pH 5.5 from the values observed at pH 5.95. The use of 7H12 broth at pH 5.95 simplified the radiometric PZA susceptibility test by avoiding the addition of acid solutions in the course of cultivation, which was required when the test was performed at pH 5.5. An additional benefit of using pH 5.95 instead of pH 5.5 was that all tested strains grew at pH 5.95, while some of them, especially PZA-resistant strains, did not grow at pH 5.5.
Three methods were used for the recovery of mycobacteria from blood specimens obtained from acquired immunodeficiency syndrome patients: (i) inoculation of 7H11 agar plates with a concentrated specimen, (ii) inoculation of 7H12 BACTEC vials with a concentrated specimen, and (iii) inoculation of 7H13 BACTEC vials with a nonconcentrated specimen. In this study, we examined 255 specimens and obtained positive mycobacterial growth in 47 of them. Among these 47 cultures, 40 were found to be positive by all three methods, and the total recovery rates in relation to these culture-positive specimens were 94% for method 1, 89% for method 2, and 96% for method 3. The advantages and disadvantages of these three methods are discussed.
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One hundred and sixty clinical isolates of Mycobacterium tuberculois were tested for their sensitivity to pyrazinamide (PZA) using the conventional proportion method (Middlebrook 7H10 agar) and the results compared to the pyrazinamidase (PZase) activity of the strains. The correlation between strains susceptible to PZA and the production of PZase was 99%. None of the isolates were exclusively resistant to PZA. At present the rate of initial PZA resistance in Kanton Zurich is 0.6%.
Transmission of Mycobacterium tuberculosis by the flexible fiberoptic bronchoscope was suspected in two patients with positive cultures from bronchial washings but with negative cultures from sputum specimens and no clinical or radiological evidence of active tuberculosis, In both cases, a patient with sputum smear-positive pulmonary tuberculosis had been examined with the same bronchoscope the day before. In one case, mycobacteriophage typing of the cultures of the consecutively examined patients revealed the same phage type in both patients, suggesting transmission by the fiber bronchoscope. In the other case, however, transmission was ruled out by different phage types. Among the few previously reported cases of transmission of Mycobacterium tuberculosis by the flexible fiberoptic bronchoscope, one case of tuberculin conversion occurred. Without antituberculous therapy our patient had negative sputum cultures and no evidence of tuberculosis one year after bronchoscopy. Transmission of other microorganisms and possible causes of transmission by the fiberoptic bronchoscope are reviewed and discussed.
Two cases of primary gastrointestinal tuberculosis are reported. One patient showed radiologic, colonoscopic and histopathologic features of Crohn's disease. After a five-year follow-up, acid-fast bacilli were identified in colonic tissue cultures. In both patients fecal cultures were repeatedly negative for Mycobacterium tuberculosis. The two patients were successfully treated with antituberculous therapy. The authors emphasize the importance of considering tuberculosis in patients presenting with Crohn's disease. In this regard colonoscopy with tissue culture of targeted biopsy may be a valuable aid in establishing the diagnosis of tuberculous colitis.
Ten critically ill patients presenting with nosocomial infection caused by Serratia marcescens (SM) not responding to prior chemotherapy were treated in an open study with Moxalactam (MOX) alone [6] or in combination with an aminoglycoside [4]. In initial disc diffusion tests, all isolates of SM were highly susceptible to MOX. Clinically, three patients were cured and four improved. Three patients died: one from SM pneumonia, one from gangrenous cholecystitis and another from ARDS. Bacteriologically, SM were eliminated from blood cultures in all seven patients with septicemia but were recovered post mortem from the lung of one patient. In three cases with localized infection, SM were eliminated once and persisted twice. Selection of resistant SM was observed in three patients but became clinically relevant in one case only. Resistant SM strains also showed reduced susceptibility to other cephalosporins and aminoglycosides. Emergence of enterococci occurred four times, in two cases with clinical consequences. MOX is a useful drug for the treatment of SM infections, but a definite risk of selecting multiresistant SM strains and of enterococcal overgrowth must be kept in mind.
An outbreak of C. jejuni enteritis involving participants of a jogging rally is described. Information was obtained by questionnaire about food consumption, incubation period, duration of illness and symptomatology. A drink prepared with raw milk was incriminated as vehicle of the outbreak. More than 500 runners were symptomatic with an attack rate of over 75%. Secondary cases were rare. Using serotyping, milk from a single cow fecally excreting C. jejuni type 2 was suspected to be the outbreak vehicle.
Statistics on the number, species and diagnosis of mycobacteria isolated from human specimens in 1981 at the Institute of medical microbiology of the University of Zurich are presented. 83% of the strains obtained from patients were classifiable as typical mycobacteria whereas 17% proved to be MOTT (mycobacteria other than tubercle bacilli). The clinical significance of the isolated species was assessed according to the criteria of Yamamoto et al. (Amer. Rev. resp. Dis. 96, 773-778 [1967]) and Wolinsky (Amer. Rev. resp. Dis. 119, 107-159 [1979]). Only in one out of 40 patients from whom MOTT (M. avium) was isolated could a causal connection be assumed between the isolate and the patient's disease. All microscopic determinations of specimens containing MOTT yielded negative results except that described above (in which 3 smears out of 6 were positive). Several Swiss laboratories have recently reported a significant increase in MOTT isolates.
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Antibiotic use was evaluated retrospectively in 1229 patients of a university hospital (Basle, Switzerland). The frequency with which antibiotics were prescribed, the indication, duration of treatment, side-effects and clinical results were compared in relation to various subspecialities. 38.1% of medical, 36.4% of surgical and 24.4% of gynecological patients received one or more antibiotic during hospitalization. The main indications for antibiotic treatment were respiratory infection (57.8%) and urinary tract infections (21%) in medical patients, prophylaxis (38%) and urinary tract infections (23%) in surgery, and urinary tract infections (43%) and adnexitis or endometritis (23%) in gynecology. Amoxycillin or penicillin G were the first-line drugs for respiratory infection, cotrimoxazole for urinary tract infection and cefalothin or cefacetrile for surgical prophylaxis. Patients with endometritis or adnexitis usually received clindamycin in combination with an aminopenicillin. Aminoglycosides were employed in only 9.5% of antibiotic courses. Information on adverse reactions in the records was scanty, only generalized exanthem (13 cases) and nausea/vomiting (2 cases) being specifically mentioned. The therapeutic result was classified by the responsible physician as cure in 50.8% or definite improvement in 16.4% of patients. However, in 118 cases (29.7%) the contribution of antibiotics to the clinical outcome could not be evaluated retrospectively.
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