Biomedical subjects
Publications and source records attributed to P H Edelstein.
A new biotype of L. dumoffii was isolated from lung and sputum samples of an immunosuppressed patient with pneumonia. This strain differs from other described strains of L. dumoffii in that it fails to produce browning of tyrosine-containing buffered yeast extract medium.
Twenty-four lower respiratory tract samples taken from patients with culture-confirmed Legionella pneumophila infection were examined with three different direct immunofluorescent antisera to L. pneumophila, as were 29 samples from similar sources taken from patients without Legionnaires disease. The reagents studied were Genetic Systems Corp. (GS) monoclonal L. pneumophila conjugate, which reacts with all known serogroups of L. pneumophila, BioDx polyvalent L. pneumophila serogroups 1 through 6 conjugate, and Centers for Disease Control polyvalent pool A L. pneumophila serogroups 1 through 4 conjugate. The specimens had been frozen at -70 degrees C for 0.5 to 5 years. Randomization was used in coding the samples, which were stained and read by an independent observer. All three conjugates correctly identified all positive and negative samples. No difference was noted among the conjugates in the absolute numbers of fluorescent L. pneumophila bacteria per sample. The GS conjugate had a much cleaner background than did the other two reagents. Mean staining intensity scores were 3.4, 3.9, and 3.7 for the GS, BioDx, and Centers for Disease Control conjugates, respectively. This study demonstrates that the diagnostic efficiency of all three conjugates is equivalent. Since the GS conjugate is easier to read, does not cross-react with non-L. pneumophila bacteria, and reacts with serogroups 1 through 10 of L. pneumophila, it appears to be preferable for use in diagnostic testing on nonhistopathologically processed specimens.
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A guinea pig model of Legionnaires' disease was produced by intratracheal inoculation of Legionella pneumophila. The bacterial inoculum given reproducibly resulted in a 95% fatality rate in untreated animals. These animals had lung histopathologic and bacteriologic findings almost identical to those found in human Legionnaires' disease. Administration of cefoxitin and gentamicin, which inhibited the infecting strain in low antibiotic concentration in vitro, was no more effective than saline; this occurred despite adequate serum and lung levels of the drugs. Erythromycin, rifampin, doxycycline, and cotrimoxazole significantly reduced fatality rates. The combinations of erythromycin with rifampin and doxycycline with rifampin were not significantly better or worse than use of either drug alone. In animals treated with any regimen containing rifampin, a dramatically higher rate of bacterial killing was observed than that observed in those animals treated with erythromycin or doxycycline alone. Also, animals treated with any regimen containing rifampin had significantly less late lung histologic evidence of pneumonia than did those treated with other agents. No rifampin-induced resistance was found. This animal model reflects prior clinical findings, provides experimental grounds for therapy with drugs other than erythromycin, and suggests that therapy of Legionnaires' disease should probably include rifampin in most cases.
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A new serogroup of Legionella pneumophila was isolated from bronchoscopic washings and an open-lung biopsy specimen of a patient from California with pneumonia. A serologically identical isolate was obtained from tap water of a hospital ward in the Netherlands, and a fatal case of pneumonia in a patient from Virginia was shown retrospectively to have been caused by this new organism. The type strain of what is now serogroup 9 of L. pneumophila is IN-23-G1-C2 (American Type Culture Collection no. 35289). Disease caused by L. pneumophila serogroup 9 is not apparently different from that caused by other L. pneumophila serogroups.
Specific laboratory diagnosis of Legionnaires' disease is possible using sputum and other respiratory tract samples. Culture diagnosis, overlooked in the past, should now be the major means of laboratory diagnosis. Detection of bacterial antigen in respiratory secretions and urine by immunologic means has the advantage of speed of diagnosis (hours vs. days for culture diagnosis), but the disadvantage of the need for use of many different antibody types. Serological diagnosis, by detection of antibody changes, probably has the lowest specificity of any of the specific tests, and often takes weeks rather than days or hours to make a diagnosis of Legionnaires' disease.
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A total of 186 volunteers, including 40 hospital patients, participated in a cross-sectional survey of oropharyngeal colonization with Legionella pneumophila. Colonization was defined as the appearance of any L. pneumophila organisms on culture or a positive direct fluorescent-antibody (FA) test or both in the absence of signs or symptoms of pneumonia. The direct FA tests were performed on throat swabs, using a polyvalent conjugate directed against L. pneumophila serogroups I through IV. Throat swabs were cultured for L. pneumophila on a selective medium. Blood specimens were tested for antibody, using an indirect FA test and heat-killed polyvalent antigen for L. pneumophila serogroups I through IV. Eight people, none of whom had pneumonia or fever, had positive direct FA tests; no subject had a positive culture for L. pneumophila. Whether the positive direct FA results represent colonization cannot be stated with assurance. In any case, the results suggest that colonization occurs infrequently.
Culture diagnosis of Legionella infections is feasible in most instances. Using selective culture techniques, sputum can be used to diagnose these infections specifically, and with a degree of sensitivity equal to or greater than currently used immunological means of diagnosis. Every laboratory performing diagnostic testing for this group of infections should perform cultures to achieve optimal yield.
An enzyme-linked immunosorbent assay was developed to detect urinary antigen excreted by patients with Legionnaires' disease. Of 47 patients tested, antigen was detected in 39. Of these 39 specimens, 35 gave clearly positive results by visual analysis; four others required spectrophotometric verification of positive results. Antigen was not detected in any of 178 urine specimens from patients with other pulmonary, bacteremic or urinary tract infections after a quick and simple confirmatory test. The assay required more time to perform than a previously described radioimmunoassay but was of equivalent sensitivity and specificity and did not require expensive equipment or contract with radioactive reagents. We conclude that enzyme-linked immunosorbent assay is a rapid, sensitive and specific means for rapidly diagnosing legionnaires' disease that can be performed in clinical laboratories unwilling or unable to use radioisotopes.
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Thirty-three strains of Legionella spp., 29 of which were L. pneumophila, were tested for their susceptibilities to erythromycin (EM), rosaramicin, tylosin, mycinamicin I (Sch-27897), and mycinamicin II (Sch-27896). Testing was performed using an agar dilution method with two different types of media: buffered charcoal yeast extract medium supplemented with 0.1% alpha-ketoglutarate (BCYE alpha) and filter-sterilized yeast extract medium with 0.1% alpha-ketoglutarate (BYE alpha). The minimal inhibitory concentrations (MICs) of the drugs tested relative to the MICs of erythromycin were: rosaramicin, MIC approximately equal to 0.2 EM MIC; tylosin, MIC approximately equal to 2 EM MIC; mycinamicin I, MIC approximately equal to 0.5 EM MIC; and mycinamicin II, MIC approximately equal to EM MIC. Both types of media caused equivalent partial inactivation of the macrolides which was apparently due entirely to pH effect. MICs on BCYE alpha were one to five times more than those observed on BYE alpha; this may be due to poorer growth on BYE alpha.
The effect of ozonation of supply water for one wing of an unoccupied hospital building which had positive cultures for Legionella pneumophila from multiple potable water fixtures was studied in a prospective, controlled fashion. Mean ozone residual concentrations of 0.79 mg/liter eradicated L. pneumophila from the fixtures, but so did nonozonated water in the control wing fixtures. The efficacy of the nonozonated water was most probably due to a mechanical flushing effect and to an unexpected rise in the chlorine content of the supply water. Determination of the in vitro activity of ozone against L. pneumophila did not predict the efficacy of its eradication from water fixtures treated with ozone.
Eighty-five potable water samples were analyzed for the presence of Legionella pneumophila by direct plating and by guinea pig inoculation methods. Direct plating methods utilized antimicrobial-containing media with and without acid treatment of specimens before inoculation. Thirty-three specimens were culture positive for L. pneumophila by one or both techniques. A total of 14 specimens were positive for L. pneumophila by direct plating only, and 2 specimens were positive for L. pneumophila by guinea pig inoculation only. The sensitivity of direct plating is significantly greater than that of guinea pig inoculation when isolating L. pneumophila from potable water (P less than 0.01).
A total of 100 water samples, 95% of which were taken from hospital potable water fixtures, were cultured on three different media used for the isolation of Legionella pneumophila. The media used were buffered charcoal-yeast extract medium (BCYE alpha medium), BCYE alpha medium with antimicrobial agents (BMPA alpha medium), and BCYE alpha medium with antimicrobial agents, glycine, and differential dyes (MWY medium). An acid wash procedure was also used for specimens plated on BCYE alpha and BMPA alpha media. A total of 24 samples were culture positive for L. pneumophila by one or more techniques. MWY medium detected 92% of positive cultures, BCYE alpha medium with the acid wash detected 83% of positive cultures, BMPA alpha medium detected 79% of positive cultures. BCYE alpha medium detected 71% of positive cultures, and BMPA alpha medium with the acid wash detected 62% of positive cultures. MWY medium was the best medium for isolating L. pneumophila from potable water specimens and can probably be depended upon as the sole medium for this type of testing.
Heating of Legionella pneumophila and other Legionella spp. was studied to determine whether this technique could be used as a selective technique with contaminated clinical specimens. Studies of 13 different strains of Legionella spp. showed heterogeneous heat survival; heating at 60 degrees C for 1 to 2 min did not affect the survival of the majority of strains. Heating of four Pseudomonas aeruginosa strains at 60 degrees C for 2 min reduced bacterial counts by 98% or greater. Enterococci were heat tolerant, with virtually no inhibition under the same conditions. No inoculum effect was noted for any of the organisms tested. Heating of eight contaminated clinical specimens before plating on buffered charcoal-yeast extract medium reduced the numbers of contaminants on most plates but increased by only one the number of specimens yielding L. pneumophila. Plating the same specimens on selective media with or without heat pretreatment yielded L. pneumophila in every case. Heating of clinical specimens at 60 degrees C for 1 to 2 min before plating may occasionally increase the recovery of L. pneumophila from contaminated specimens, but this technique should not be generally used.
A new species of Legionella that caused pneumonia in a patient with chronic lymphocytic leukemia has been characterized. The Legionella wadsworthii species nova is proposed for this bacterium. The type strain is Wadsworth 81-716A (American Type Culture Collection 33877). The new species differs phenotypically from L. pneumophila in that the predominant cellular fatty acid is methyl-12-methyltetradecanoic acid (a-15:0) rather than methyl-14-methylpentadecanoic acid (i-16:0), and in its failure to react with L. pneumophila antiserum. The clinical illness caused by L. wadsworthii was not apparently different from that seen with other legionella infections, except for prolonged fever and slow resolution of pulmonary infiltrates.