Non-tuberculous mycobacteria: epidemiological pattern in a reference laboratory and risk factors associated with pulmonary disease.

The diseases caused by non-tuberculous mycobacteria (NTM), in both AIDS and non-AIDS populations, are increasingly recognized worldwide. Although the American Thoracic Society published the guidelines for diagnosis of NTM pulmonary disease (NTM-PD), the diagnosis is still difficult. In the first part of the study, we collected data on NTM isolates in the Mycobacteriology Laboratory of Careggi Hospital (Florence, Italy) and analysed the epidemiological data of NTM isolates. Then, to analyse the risk factors associated to NTM-PD, we studied the presence of ATS/IDSA criteria for NTM-PD in patients who had at least one positive respiratory sample for NTM and were admitted to the Infectious Disease Unit and the Section of Respiratory Medicine. We selected 88 patients with available full clinical data and, according to ATS/IDSA criteria, classified 15 patients (17%) as NTM-PD cases and 73 as colonized patients (83%). When comparing colonized and NTM-PD patients we did not find significant differences of age, gender and comorbidity. We observed that Mycobacterium avium and M. intracellulare were statistically associated with NTM-PD (P = 0·001) whereas M. xenopi was statistically associated with colonization. Although the number of studied patients is limited, our study did not identify risk factors for NTM-PD that could help clinicians to discriminate between colonization and disease. We underline the need of close monitoring of NTM-infected patients until the diagnosis is reasonably excluded. Further larger prospective studies and new biological markers are needed to identify new useful tools for the diagnosis of NTM-PD.

First case of Mycobacterium marseillense lymphadenitis in a child.

BACKGROUND: Nontuberculous mycobacteria (NTM) are pathogens that commonly affect the paediatric population and its most frequent manifestation is a cervicofacial lymphadenopathy. With the improvement of technologies, new species have been recently identified. CASE PRESENTATION: We report the first case of NMT lymphadenitis in a child caused by Mycobacterium marseillense, a newly described species belonging to Mycobacterium avium complex. CONCLUSIONS: Improving the identification of these newly discovered mycobacteria, further information will be available about their clinical involvement and their best treatment.

Cultural studies on two isolates of "Mycobacterium genavense" from patients with acquired immunodeficiency syndrome.

Two strains of the newly proposed species "Mycobacterium genavense" have been isolated, using the radiometric system (Bactec, Becton Dickinson), from the blood of two HIV-infected patients. Disseminated infections due to the new organism closely resemble those of the Mycobacterium avium complex, with prevalently intestinal symptomatology. We report here on the cultural behavior of the isolates, which are enhanced at pH 6, are inhibited by NAP, do not require supplements, and grow best at 37 degrees C. We also report on the antibiotic susceptibility of the isolates.

Dobutamine as palliative drug in home-care advanced cancer patients.

We describe a patient with advanced cancer whose severe symptoms of congestive heart failure were successfully treated with dobutamine. The intermittent intravenous administration of dobutamine 5 micrograms/kg/min for 3 hr per day at home enabled control of dyspnea, leg edema, and pain, and increased urine output after 1 day. An improvement in renal function was observed in the following days. The mechanism and the utility of a palliative approach with dobutamine are discussed.

Home palliative care: results in 1991 versus 1988.

Home care is greatly expanding because of the savings it offers by avoiding unnecessary hospitalization and also because patients benefit from being in their own home environments. Since 1988, Societa Assistenza Malato Oncologico Terminale (SAMOT) has organized a pain relief and home palliative care unit for terminal cancer patients. Objectives, difficulties, protocols, and achievements of 4 years of experience were examined, and the findings of the various years were compared. Our results suggest that considerable progress has been made in home palliative care. There are still social and cultural difficulties to overcome, however.

HPLC does not differentiate Mycobacterium paratuberculosis from Mycobacterium avium.

HPLC, which is gaining its place as identification tool in mycobacteriology laboratories, has been proposed to distinguish Mycobacterium paratuberculosis from Mycobacterium avium. We had reported no significant difference between M. avium and M. paratuberculosis reference strain ATCC 19698. Because of the advantages offered by such a method, we enlarged our observations to include more isolates of M. paratuberculosis. Within the double cluster of peaks obtained by both M. avium and M. paratuberculosis, we could not find a consistent difference typical of M. paratuberculosis. Therefore, the present study confirmed that M. avium and M. paratuberculosis could not be distinguished by HPLC, raising doubts of a straightforward use of HPLC to identify M. paratuberculosis.

Radiometric susceptibility testing of Mycobacterium xenopi.

Mycobacterium xenopi is an opportunistic pathogen, frequently isolated in various areas of Europe from pulmonary specimens, which may also cause infections in AIDS patients. We used the Bactec radiometric system (Becton Dickinson, USA) with a procedure expressly adapted to the particular growth characteristics of M. xenopi to determine the susceptibility patterns of 40 clinical isolates to six antimicrobial drugs. The majority of the strains were resistant to ethambutol and susceptible to amikacin, ciprofloxacin, rifampin, rifabutin and streptomycin.

Investigation on several phenotypic features in two strains of Mycobacterium genavense.

The newly recognized species Mycobacterium genavense causes disseminated infections in AIDS patients, but its prevalence is difficult to assess because of its inability to grow on standard solid media. For the same reason, very little is known about the phenotypic traits of its isolates. We report here the results of our studies on two such strains isolated from AIDS patients and subcultured on a non-standard solid medium. Besides several features conventionally explored for mycobacterial speciation, we tested the isolates for 19 enzymatic activities and determined their mycolic acids profiles by means of high performance liquid chromatography. We also compare our findings with the scanty literature data on the laboratory characteristic and antimicrobial susceptibility of M. genavense.

[Intestinal mycobacterial infections in AIDS. Clinical course and treatment of infections caused by Mycobacterium avium, Mycobacterium kansasii, Mycobacterium genavense]. / Micobatteriosi intestinali in AIDS. Clinica e terapia delle infezioni da Mycobacterium avium, Mycobacterium kansasii, Mycobacterium genavense.

Digestive apparatus is a common target of atypical mycobacteriosis in AIDS patients (at least 50% of patients with CD4+ lymphocytes < 50/mm3). We describe the clinical-histological features of two cases of Whipple-like syndrome likely caused by Mycobacterium avium (MAI) (study performed by light and electron microscopy), of one case of infection caused by two morphological variants of a MAI strain with a different sensitivity to antibiotics, of one case of M. kansasii infection and of two cases of M. genavense infection accompanied by sensitivity tests to antibiotics (as far as we know, these are the first described quantitative sensitivity tests of M. genavense to antibiotics). In conclusion, we discuss the present therapeutical outlines for M. kansasii and avium, together with the teramporary pharmacological options for M. genavense as suggested by antibiotic sensitivity tests performed on the strains isolated from the studied patients.

Isolation of Mycobacterium shimoidei from a patient with cavitary pulmonary disease.

Mycobacterium shimoidei was isolated from the sputum of a man hospitalized for cavitary pulmonary disease. This is the fourth isolation of M. shimoidei to be reported; the organism has also been isolated in Japan, Australia, and Germany.

Evaluation of a commercial ligase chain reaction kit (Abbott LCx) for direct detection of Mycobacterium tuberculosis in pulmonary and extrapulmonary specimens.

Direct detection of Mycobacterium tuberculosis by means of a commercial ligase chain reaction DNA amplification method (LCx M. tuberculosis; Abbott Diagnostics Division, Abbott Park, Ill.) was investigated with 511 (including 147 extrarespiratory) specimens collected from 358 patients. LCx results were compared with standard microbiological data, and conflicting cases were resolved according to the final clinical diagnosis. M. tuberculosis was detected in 45 of 358 subjects by means of the LCx test. The test was negative for all 30 specimens with mycobacteria other than M. tuberculosis. The sensitivity, specificity, and positive and negative predictive values for the LCx test, compared with culture results, were 93.90, 92.31, 70.00, and 98.75%, respectively; these values rose in resolved cases to 95.53, 99.25, 97.27, and 98.75%, respectively. With respiratory specimens, for which the LCx system is licensed, the sensitivity reached 98.97%. In patients with a final clinical diagnosis of tuberculosis the sensitivity of the LCx system was 89.36% compared to 82.98% for cultures and 78.72% for microscopy. We conclude that the LCx test is user friendly, rapid, fairly sensitive, and highly specific. It can also be effectively used on extrapulmonary specimens provided possible false-negative results are taken into account. However, the use of LCx test appears to be less appropriate for the monitoring of antituberculosis therapy, as the majority of samples from treated tuberculosis patients gave consistently positive results, despite the sterilization of cultures.

Evaluation of reformulated chemiluminescent DNA probe (AccuProbe) for culture identification of Mycobacterium kansasii.

A panel of 104 isolates belonging to the species Mycobacterium kansasii and 78 mycobacterial isolates belonging to other species was tested in parallel with the present commercially available DNA probe (AccuProbe; Gen-Probe) and with a new probe just developed by the same manufacturer. While the old version of the probe confirmed the previously reported low sensitivity (only 59% of the M. kansasii isolates reacted), the new one was 100% sensitive. Only two non-M. kansasii strains, both M. gastri isolates, gave false-positive hybridization results.

Early detection of Mycobacterium tuberculosis in BACTEC cultures by ligase chain reaction.

The LCx Mycobacterium tuberculosis ligase chain reaction system (Abbott Diagnostic Division, Abbott Park, Ill.) was used to detect M. tuberculosis in 150 consecutive BACTEC vials on the day on which a positive growth index (GI) was recorded. By LCx, M. tuberculosis DNA was detected in BACTEC vials on average 2.6 days before the presence of acid-fast bacilli could be confirmed by microscopic examination. A total of 106 of 108 M. tuberculosis isolates were detected without centrifugation from bottles presenting very low GIs (average, 70; median, 33). No false-positive result was obtained from nontuberculous mycobacteria or from isolates with contaminants.

Utility of high-performance liquid chromatography for identification of mycobacterial species rarely encountered in clinical laboratories.

High-performance liquid chromatography (HPLC) has been demonstrated to be a suitable technique for determining the species of mycobacteria on the basis of their mycolic acid pattern. Representative HPLC profiles, which are needed for the visual recognition of chromatograms, have been published for the most frequently encountered mycobacterial species. No extensive study has been reported for less common species, and only a few, scattered chromatographic patterns are available in literature. This study evaluates the utility of this technique for the identification of several rare species. Mycobacterium celatum, Mycobacterium genavense and Mycobacterium simiae chromatographic profiles have been verified, and previously unreported profiles of other species investigated. The chromatographic pattern of Mycobacterium malmoense is presented for the first time.

Tentative evidence of AIDS-associated biotype of Mycobacterium kansasii.

Previous studies revealed heterogeneous behavior within the species Mycobacterium kansasii against commercially available DNA probes (Accuprobe M. kansasii culture identification test; Gen-Probe); several isolates, conventionally identified as M. kansasii, failed in fact to hybridize. Looking for a possible association with phenotypic features, we tested a fully characterized panel of 69 clinical isolates of M. kansasii (19 of which were Accuprobe negative) with a semiquantitative micromethod which tests for 19 enzymatic activities (Api Zym; BioMérieux). The strains were from 25 hospitals in 18 Italian towns; 20 isolates came from human immunodeficiency virus type 1-positive patients who fulfilled the Centers for Disease Control criteria for AIDS diagnosis. On the basis of the whole set of phenotypic traits, our strains clustered in two groups, allowing the differentiation of biotypes within the species. There was a perfect association between biotype 2 and hybridization failures with Accuprobe and a very significant association between this novel biotype 2 and AIDS status, which suggests that it differs in virulence.

Evaluation of a commercial DNA probe assay for the identification of Mycobacterium kansasii.

A commercially available DNA probe (the AccuProbe Mycobacterium kansasii culture identification test, Gen-Probe, USA) for the identification of Mycobacterium kansasii was tested on a panel of 143 fully characterized mycobacterial strains. The isolates included 70 Mycobacterium kansasii and 73 mycobacteria other than kansasii. The specificity was 100% while the sensitivity was 72.8%. This sensitivity is unusually low in comparison with that of commercial DNA probes for other mycobacteria and confirms a previous study that found genetic heterogeneity within the species Mycobacterium kansasii. Strains that do not hybridize with the AccuProbe are particularly prevalent in Italy and perhaps elsewhere in Europe.

Pulmonary infection due to Mycobacterium szulgai, case report and review of the literature.

We describe the case of a patient with a chronic pulmonary infection due to a mycobacterium tentatively identified as Mycobacterium flavescens, but finally shown to be Mycobacterium szulgai; this is the first M. szulgai infection reported in Italy. The patient responded to treatment with multiple antituberculosis drugs only after two cycles of 10 and 6 months, respectively. The literature concerning previous case reports in which M. szulgai is involved is revised and the difficulty concerning the identification of this rare mycobacterium, along with its in vitro and in vivo susceptibility, are discussed.