The nature of mycobacterial disease in south east England, 1977-84

Clinical Characteristics and Antimicrobial Susceptibility of Mycobacterium intracellulare and Mycobacterium abscessus Pulmonary Diseases: A Retrospective Study

The incidence of nontuberculous mycobacteria (NTM) diseases is increasing every year. The present study was performed to investigate the clinical characteristics, CT findings, and drug susceptibility test (DST) results of patients diagnosed with M. intracellulare or M. abscessus nontuberculous mycobacterial pulmonary disease (NTMPD). This retrospective study included patients diagnosed with NTMPD due to M. intracellulare or M. abscessus for the first time at Anhui Chest Hospital between 01/2019 and 12/2021. The patients were grouped as M. intracellulare-NTMPD group or M. abscessus-NTMPD group. Clinical features, imaging data and DST data, were collected. Patients with M. intracellulare infection had a higher rate of acid-fast smears (66.1% vs. 45.2%, P=0.032) and a higher rate of cavitation based on pulmonary imaging (49.6% vs. 19.4%, P=0.002) than patients with M. abscessus infection, but both groups had negative TB-RNA and GeneXpert results, with no other characteristics significant differences. The results of DST showed that M. intracellulare had high susceptibility rate to moxifloxacin (95.9%), amikacin (90.1%), clarithromycin (91.7%), and rifabutin (90.1%). M. abscessus had the highest susceptibility rate to amikacin (71.0%) and clarithromycin (71.0%). The clinical features of M. intracellulare pneumopathy and M. abscessus pneumopathy are highly similar. It may be easily misdiagnosed, and therefore, early strain identification is necessary. M. intracellulare has a high susceptibility rate to moxifloxacin, amikacin, clarithromycin, and rifabutin, while M. abscessus has the highest susceptibility rate to amikacin and clarithromycin. This study provides an important clinical basis for improving the management of NTMPD.

Fatal pulmonary cavitary disease secondary to Mycobacterium xenopi in a patient with sarcoidosis

Introduction: Mycobacterium xenopi (M. xenopi) has low pathogenicity and usually requires either host immune impairment or structural lung disease to cause clinical disease. Fatal cavitary infection in a patient without immunosuppression is rarely presented. Case report: A 62-year-old female with history of sarcoidosis and hypertension presented with cough, fever and dyspnea for one week. Chest imaging showed irregular opacification of upper lung zones. The sputum samples tested positive for acid-fast bacilli (AFB) and the subsequent testing identified M. xenopi. She was started on rifampin, isoniazid, pyrazinamide and ethambutol along with azithromycin, and was discharged with plans to continue the same. A follow up sputum test was negative for AFB. She was, however, readmitted ten months later with sepsis due to pneumonia. Chest imaging revealed worsening cavitary lung lesions. Despite starting her on intravenous antibiotics while continuing anti-tubercular therapy, she developed severe respiratory distress and had to be intubated. Her condition continued to deteriorate and she expired the following day. Conclusion: Fatal cavitary infections with M. xenopi have been reported in the absence of established optimal management. Well-designed studies with sufficient power are needed to establish new treatment guidelines.

Nontuberculous mycobacteria in Middle East: Current situation and future challenges

Nontuberculous mycobacteria (NTM) are a diverse group of bacterial species that are distributed in the environment. Many of these environmental bacteria can cause disease in humans. The identification of NTM in environmental sources is important for both clinical and epidemiological purposes. In this study, the distribution of NTM species from environmental and clinical samples in the Middle East was reviewed. In order to provide an overview of NTM, as well as recent epidemiological trends, all studies addressing NTM in the Middle East from 1984 to 2014 were reviewed. A total of 96 articles were found, in which 1751 NTM strains were isolated and 1084 of which were obtained from clinical samples, 619 from environmental samples and 48 were cited by case reports. Mycobacterium fortuitum was the most common rapid growing mycobacteria (RGM) isolated from both clinical (269 out of 447 RGM; 60.1%) and environmental (135 out of 289 RGM; 46.7%) samples. Mycobacterium avium complex (MAC) was the most common slow growing mycobacteria (SGM) isolated from clinical samples (140 out of 637 SGM; 21.9%). An increasing trend in NTM isolation from the Middle East was noted over the last 5years. This review demonstrates the increasing concern regarding NTM disease in the Middle East, emphasizing the need for regional collaboration and coordination in order to respond appropriately.

Nontuberculous mycobacterial pulmonary infections

Pulmonary infections due to nontuberculous mycobacteria (NTM) are increasingly recognized worldwide. Although over 150 different species of NTM have been described, pulmonary infections are most commonly due to Mycobacterium avium complex (MAC), Mycobacterium kansasii, and Mycobacterium abscessus. The identification of these organisms in pulmonary specimens does not always equate with active infection; supportive radiographic and clinical findings are needed to establish the diagnosis. It is difficult to eradicate NTM infections. A prolonged course of therapy with a combination of drugs is required. Unfortunately, recurrent infection with new strains of mycobacteria or a relapse of infection caused by the original organism is not uncommon. Surgical resection is appropriate in selected cases of localized disease or in cases in which the infecting organism is resistant to medical therapy. Additionally, surgery may be required for infections complicated by hemoptysis or abscess formation. This review will summarize the practical aspects of the diagnosis and management of NTM thoracic infections, with emphasis on the indications for surgery and the results of surgical intervention. The management of NTM disease in patients with human immunodeficiency virus (HIV) infections is beyond the scope of this article and, unless otherwise noted, comments apply to hosts without HIV infection.

Rapid Identification of Mycobacterium tuberculosis and nontuberculous mycobacteria by multiplex, real-time PCR

The rapid identification of mycobacteria from culture is of primary importance for the administration of empirical antibiotic therapy and for the implementation of public health measures, yet there are few commercially available assays that can easily and accurately identify the mycobacteria in culture in a timely manner. Here we report on the development of a multiplex, real-time PCR assay that can identify 93% of the pathogenic mycobacteria in our laboratory in two parallel reactions. The mycobacteria identified by this assay include the Mycobacterium tuberculosis complex (MTC), the M. avium complex (MAC), the M. chelonae-M. abscessus group (MCAG), the M. fortuitum group (MFG), and M. mucogenicum. The primer targets included the 16S rRNA gene and the internal transcribed spacer. The assay was initially validated with a repository of reference strains and was subsequently tested with 314 clinical cultures identified by the AccuProbe assay or high-performance liquid chromatography. Of the 314 cultures tested, multiplex, real-time PCR produced congruent results for 99.8% of the 1,559 targets evaluated. The sensitivity and the specificity were each 99% or greater for MTC (n = 96), MAC (n = 97), MCAG (n = 68), and M. mucogenicum (n = 9) and 95% and 100%, respectively, for MFG (n = 19). We conclude that this multiplex, real-time PCR assay is a useful diagnostic tool for the rapid and accurate identification of MTC and clinically relevant nontuberculous mycobacteria.

Cavitary pulmonary disease

A pulmonary cavity is a gas-filled area of the lung in the center of a nodule or area of consolidation and may be clinically observed by use of plain chest radiography or computed tomography. Cavities are present in a wide variety of infectious and noninfectious processes. This review discusses the differential diagnosis of pathological processes associated with lung cavities, focusing on infections associated with lung cavities. The goal is to provide the clinician and clinical microbiologist with an overview of the diseases most commonly associated with lung cavities, with attention to the epidemiology and clinical characteristics of the host.

Asymptomatic Mycobacterium xenopi lung abscess in an immunocompetent male without pre-existing lung pathology

Like other non-tuberculous mycobacteria, Mycobacterium xenopi infects more commonly patients with altered immune defenses. In immunocompetent individuals, infection with M. xenopi has been described in the setting of underlying lung disease. We here report the first case of M. xenopi lung abscess in a previously healthy patient with no known predisposing factors who was successfully treated with rifampin, isoniazid and ethambutol.

Human Mycobacterium bovis infection in the United Kingdom: Incidence, risks, control measures and review of the zoonotic aspects of bovine tuberculosis

Amongst the members of the Mycobacterium tuberculosis complex (MTBC), M. tuberculosis is mainly a human pathogen, whereas M. bovis has a broad host range and is the principal agent responsible for tuberculosis (TB) in domestic and wild mammals. M. bovis also infects humans, causing zoonotic TB through ingestion, inhalation and, less frequently, by contact with mucous membranes and broken skin. Zoonotic TB is indistinguishable clinically or pathologically from TB caused by M. tuberculosis. Differentiation between the causative organisms may only be achieved by sophisticated laboratory methods involving bacteriological culture of clinical specimens, followed by typing of isolates according to growth characteristics, biochemical properties, routine resistance to pyrazinamide (PZA) and specific non-commercial nucleic acid techniques. All this makes it difficult to accurately estimate the proportion of human TB cases caused by M. bovis infection, particularly in developing countries. Distinguishing between the various members of the MTBC is essential for epidemiological investigation of human cases and, to a lesser degree, for adequate chemotherapy of the human TB patient. Zoonotic TB was formerly an endemic disease in the UK population, usually transmitted to man by consumption of raw cows' milk. Human infection with M. bovis in the UK has been largely controlled through pasteurization of cows' milk and systematic culling of cattle reacting to compulsory tuberculin tests. Nowadays the majority of the 7000 cases of human TB annually reported in the UK are due to M. tuberculosis acquired directly from an infectious person. In the period 1990-2003, between 17 and 50 new cases of human M. bovis infection were confirmed every year in the UK. This represented between 0.5% and 1.5% of all the culture-confirmed TB cases, a proportion similar to that of other industrialized countries. Most cases of zoonotic TB diagnosed in the UK are attributed to (i) reactivation of long-standing latent infections acquired before widespread adoption of milk pasteurization, or (ii) M. bovis infections contracted abroad. Since 1990, only one case has been documented in the UK of confirmed, indigenous human M. bovis infection recently acquired from an animal source. Therefore, for the overwhelming majority of the population, the risk of contracting M. bovis infection from animals appears to be extremely low. However, bovine TB is once again a major animal health problem in the UK. Given the increasing numbers of cattle herds being affected each year, physicians and other public health professionals must remember that zoonotic TB is not just a disease of the past. A significant risk of M. bovis infection remains in certain segments of the UK population in the form of (i) continuing on-farm consumption of unpasteurized cows' milk, (ii) retail sales by approved establishments of unpasteurized milk and dairy products and (iii) occupational exposure to infectious aerosols from tuberculous animals and their carcases.

Increasing incidence of Mycobacterium xenopi at Bellevue hospital: An emerging pathogen or a product of improved laboratory methods?

STUDY OBJECTIVES

To investigate the dramatic rise in number of Mycobacterium xenopi isolates identified in our mycobacteriology laboratory, and to determine if this increase was due to emerging clinical pathology or to changes in culture technique.

DESIGN

Retrospective chart and laboratory review.

SETTING

University-affiliated tertiary-care city hospital.

PATIENTS

Eighty-one patients with a single culture positive for M xenopi from 1975 to 1994 (period 1), and 47 patients with two or more cultures positive from 1994 to 1998 (period 2).

INTERVENTIONS

The Bellevue mycobacteriology laboratory changed the culture medium from solid Lowenstein-Jensen medium (used from 1975 to 1990) to the Septi-Check AFB System (Becton-Dickinson; Glencoe, MD; used from 1991 to 1994), to the Mycobacteria Growth Indication Tube (MGIT; Becton-Dickinson; used from 1995 to 1998).

MEASUREMENTS AND RESULTS

We recovered 29 M xenopi isolates from 1975 to 1990, 12 isolates from 1991 to 1994, and 381 isolates from 1995 to 1998. We subsequently identified and reviewed the medical records of all 81 patients who were culture positive for M xenopi from 1975 to 1994 (period 1), and 46 patients who had two or more isolates culture positive for M xenopi from 1995 to 1998 (period 2). For period 1, 75% of the subjects were male, 80% were minority, and at least 43% were HIV positive. Only one patient had clinical M xenopi lung disease during this period. For period 2, 79% of the subjects were male, 83% were minority, and at least 58% were HIV positive; two additional patients were identified who had clinical M xenopi lung disease.

CONCLUSIONS

The dramatic increase in M xenopi isolates noted in our hospital was due to a more sensitive laboratory isolation technique, rather than a true increase in clinical disease. Other hospitals utilizing MGIT systems for mycobacterial recovery should interpret positive M xenopi cultures with caution.

Diagnosis and treatment of disease caused by nontuberculous mycobacteria. This official statement of the American Thoracic Society was approved by the Board of Directors, March 1997. Medical Section of the American Lung Association

Diagnostic criteria of nontuberculous mycobacterial lung disease in HIV-seropositive and -seronegative hosts. The following criteria apply to symptomatic patients with infiltrate, nodular or cavitary disease, or a high resolution computed tomography scan that shows multifocal bronchiectasis and/or multiple small nodules. A. If three sputum/bronchial wash results are available from the previous 12 mo: 1. three positive cultures with negative AFB smear results or 2. two positive cultures and one positive AFB smear B. If only one bronchial wash is available: 1. positive culture with a 2+, 3+, or 4+ AFB smear or 2+, 3+, or 4+ growth on solid media C. If sputum/bronchial wash evaluations are nondiagnostic or another disease cannot be excluded: 1. transbronchial or lung biopsy yielding a NTM or 2. biopsy showing mycobacterial histopathologic features (granulomatous inflammation and/or AFB) and one or more sputums or bronchial washings are positive for an NTM even in low numbers.

COMMENTS

these criteria fit best with M. avium complex, M. abscessus, and M. kansasii. Too little is known of other NTM to be certain how applicable these criteria will be. At least three respiratory samples should be evaluated from each patient. Other reasonable causes for the disease should be excluded. Expert consultation should be sought when diagnostic difficulties are encountered.

Analysis of Mycobacterium avium complex serovars isolated from AIDS patients from southeast Brazil

The purpose of this study was to assess the distribution of Mycobacterium avium serovars isolated from AIDS patients in São Paulo and Rio de Janeiro. Ninety single site or multiple site isolates from 75 patients were examined. The most frequent serovars found were 8 (39.2%), 4 (21.4%) and 1 (10.7%). The frequency of mixed infections with serovar 8 or 4 was 37.8%. Among the 90 strains examined, M. intracellulare serovars (7 strains) and M. scrofulaceum (4 strains) were found in 11 isolates (12%) indicating that M. avium (88%) was the major opportunistic species in the M. avium complex isolates in Brazilian AIDS patients.

The prevalence of environmental mycobacteria in drinking water supply systems in a demarcated region in Czech Republic, in the period 1984-1989

The presence of environmental mycobacteria was studied in drinking water supply systems in Olomouc Country, Czech Republic, in order to detect the possible spread of M. kansasii from the neighbouring region in Ostrava County. Drinking water samples from water supply systems of 16 identical localities were investigated. The samples of running water, and tap swabs or tap scrapings were collected twice a year, in the spring and in the autumn. The most common cultivated and identified species were M. gordonae (20.4%), M. flavescens (13.8%), rapidly growing mycobacteria (5.0%) and then by occasional identification of M. fortuitum, M. terrae, M. scrofulaceum. M. kansasii was not detected. The prevalence rates showed no time trend over the period 1984-1989. We conclude that there is no evidence at present that endemic M. kansasii, isolated repeatedly from the environment in the Ostrava neighbouring region, has spread to Olomouc County.

Non-tuberculous pulmonary infections in Scotland: a cluster in Lothian?

BACKGROUND

A retrospective study was carried out to confirm the clinical impression that, in Lothian, non-tuberculous mycobacterial infections are as common as pulmonary tuberculosis.

METHODS

All pulmonary isolates of Mycobacterium tuberculosis/bovis and non-tuberculous mycobacteria in Scotland from April 1990 to March 1993, and the notes of all patients with M malmoense isolates in Lothian, were reviewed. Information on mycobacterial culture procedures in Scottish laboratories was obtained as part of an audit project.

RESULTS

Of all pulmonary isolates of mycobacteria in Lothian 53% (108/205) were non-tuberculous strains compared with 18% (140/800) for Scotland outside Lothian. Although comparable in population size and laboratory techniques, Lothian (108) had almost twice as many isolates of non-tuberculous mycobacteria as Glasgow (56), but the proportions of M malmoense and M avium intracellulare complex were similar in both areas. Of 41 patients with M malmoense isolates in Lothian 30 (75%) had clinically significant lung disease; only one was HIV positive.

CONCLUSIONS

Non-tuberculous mycobacteria pose an increasing clinical problem in Scotland as a cause of pulmonary disease. There is a cluster of cases with M malmoense infection in Lothian which cannot be attributed to the high local prevalence of HIV.

Zoonotic aspects of Mycobacterium bovis infection

The bovine tuberculosis eradication campaigns in many industrially developed countries have led to a huge reduction in the incidence of human tuberculosis caused by Mycobacterium bovis. Overt disease in man may, however, manifest decades after the initial infection and the occurrence of such disease raises several important questions. In particular, it is important to determine whether man-to-man transmission occurs, thereby rendering man a continuing reservoir of infection, and whether, if this is the case, man develops infectious forms of tuberculosis that enable M. bovis to be transmitted back to cattle. Epidemiological studies in South East England indicate that human tuberculosis due to M. bovis is rare and that the incidence is declining. In contrast to earlier days, the lung is now involved in many cases, raising the possibility of transmission of bacilli to other human beings and to cattle by the aerogenous route. No direct evidence of man-to-man transmission of overt disease was found but it is possible that inapparent primary pulmonary infections are occurring and these may proceed to overt post-primary disease in the future. The genito-urinary tract is now the most prevalent site of non-pulmonary lesions and there is firm evidence that this form of tuberculosis poses a hazard to cattle. Though uncommon, human tuberculosis due to M. bovis is still a public health problem of concern to both the medical and veterinary professions and there is a need to maintain careful bacteriological surveillance.

Association between the histological diagnosis of tuberculosis and microbiological findings

The aim of this study was to determine the association between the histological diagnosis of tuberculosis and the microbiological findings and to indicate how these results affect treatment. Histopathology and microbiology records were examined retrospectively. 89 cases were identified between 1984 and 1988. 67% were diagnosed as tuberculosis (TB) by both methods, 97% were diagnosed as TB or 'compatible with TB' by histology. For 7% of these the final diagnosis was found to be other than TB. 48% of patients diagnosed as TB on the basis of histology alone were treated for TB. 70% were diagnosed as TB by microbiology and treated. When matched and appropriate specimens were sent to both departments there was a high level of agreement between histopathologists and microbiologists. There was a problem with inappropriate specimens sent to microbiology.

Gastro-intestinal involvement in Mycobacterium avium-intracellulare infection of patients with HIV

In a study of 866 faecal specimens from 437 persons, Mycobacterium avium-intracellulare (MAI) was isolated from 14.8% patients with AIDS and 1.3% patients with symptomatic HIV infection but not from any HIV seronegative or asymptomatic HIV seropositive persons. These data support the hypothesis that the gastro-intestinal tract is the portal of entry for MAI and confirm that MAI infection is a manifestation of late-stage HIV disease. Positive faecal cultures correlated well with disseminated disease. The use of faecal cultures for early diagnosis is therefore recommended.

Mycobacterium bovis infection in human beings in contact with elk (Cervus elaphus) in Alberta, Canada

Human infection with Mycobacterium bovis is rare in developed countries because of milk pasteurisation and the slaughter of infected cattle. An epizootic of M bovis infection in domesticated elk (Cervus elaphus) in Alberta, Canada, which started in April, 1990, prompted us to seek human contacts of elk herds. There were 446 identified contacts, in 394 of whom tuberculin skin tests were done. Of 81 contacts who were skin-test positive, 50 had been in contact with culture-positive animals. 6 of 106 subjects tested a second time became tuberculin positive. 1 case of active M bovis infection was diagnosed by sputum culture. The mode of transmission of M bovis from these farm animals to man is likely to be aerosolisation of infected particles. Because of the apparent susceptibility of farmed Cervidae (deer) to M bovis infection, and the evidence of spread to man, control measures to prevent human infection should be developed.

Pediatric tuberculosis in immigrants to the United Kingdom from the Indian sub-continent

Tuberculosis (TB) is now an uncommon disease in the United Kingdom (U.K.) and its overall incidence is declining. However, the incidence of TB in immigrants from India, Pakistan, and Bangladesh (the Indian sub-continent, ISC) is much higher than in the native white population or immigrant groups from other areas, and this is so even for children of ISC ethnic origin born in the U.K. The clinical pattern of the disease also differs, extrapulmonary involvement being commoner in ISC patients than white patients. The epidemiology and management of TB in pediatric patients of ISC origin is reviewed and reasons for differences from other ethnic groups in the U.K. are discussed.

Incidence and nature of human tuberculosis due to Mycobacterium africanum in South-East England: 1977-87

A total of 210 new cases of tuberculosis due to Mycobacterium africanum were registered at the South-East Regional Centre for Tuberculosis Bacteriology, Dulwich, between 1977 and 1987 inclusive. This represented 1.25% of bacteriologically-confirmed cases of tuberculosis in South-East England, an incidence slightly higher than that of disease due to M. bovis. Two variants were identified: 150 strains were typed as African I (a type associated with East Africa) and 60 as African II (a type more prevalent in West Africa). Over half the patients infected with African I strains were of Indian subcontinent ethnic origin; patients of African ethnic origin predominated in the African II group while about a fifth o patients infected with either type were of European origin. The European patients with tuberculosis due to M. africanum were notably younger than those in the same region with disease due to other tubercle bacilli. The distribution of lesions due to M. africanum was similar to that due to other tubercle bacilli in the various ethnic groups, except that genito-urinary tuberculosis was uncommon. The importance of a clinical awareness that M. africanum is a highly pathogenic and transmissible tubercle bacillus rather than an opportunist or 'atypical' mycobacterium is stressed.

Incidence and nature of human tuberculosis due to bovine tubercle bacilli in South-East England: 1977-1987

A total of 201 new cases of tuberculosis due to bovine tubercle bacilli was confirmed in South-East England between 1977 and 1987 inclusive. This represents about 1% of all cases of tuberculosis in this region. Most cases occurred amongst older individuals of indigenous white British origin, although some younger patients of Southern European and Indian subcontinent ethnic origin were also diagnosed. The lung was the most frequent site of disease, followed by the genito-urinary tract. In view of the known risk of transmission of disease from man to cattle via the respiratory and urinary tracts, continued surveillance of this relatively uncommon form of tuberculosis is still indicated.

Pulmonary Mycobacterium kansasii infection successfully treated with a regimen containing erythromycin

We report a case in which erythromycin was used in place of rifampicin after a severe reaction to the latter in the treatment of pulmonary Mycobacterium kansasii infection.

Bovine tubercle bacilli and disease in animals and man

In 1882 Robert Koch reported the isolation oftuberkelbazillenfrom human and bovine sources. Sixteen years later, Theobald Smith (1898) demonstrated that strains of Koch's tubercle bacilli from these two hosts differed in cell morphology, cultural characteristics and virulence in rabbits. He did not believe that these variants were limited to the hosts from which they were isolated nor that the differences resulted from adaptations to a given host. Indeed, he remarked that ‘It might be better to omit the host designation of such varieties in order to anticipate assumptions that they are necessarily limited to the host whose name they bear.’ Nevertheless, heedless of his own misgivings he termed them the ‘human’ and ‘bovine’ types.

Infection and disease due to the environmental mycobacteria

Saprophytic mycobacteria are widely distributed in the environment and contact between them and man is unavoidable. Immunologically effective contact is responsible for cross-reactivity to tuberculin and there is increasing evidence that it also profoundly affects the nature of subsequent responses to BCG vaccination and to infection by the tubercle and leprosy bacilli. Some environmental mycobacteria occasionally cause overt disease. Two species, Mycobacterium ulcerans and M. marinum, cause characteristic named diseases: Buruli ulcer and swimming pool granuloma respectively. Other species cause pulmonary and non-pulmonary lesions that resemble those of tuberculosis. Disease often, but not always, occurs in individuals with predisposing factors such as damaged lungs or immunosuppressive disorders including AIDS. Diagnosis rests on the isolation and identification of the causative species and treatment is based on antituberculous therapy for extended periods or combinations of various other drugs. In contrast to tuberculosis, the incidence of these diseases appears to be on the increase in the Western world and they merit serious consideration.