Isolation of mycobacteria from patients seropositive for the human immunodeficiency virus (HIV) in south east England: 1984-92

Gastric Extramural Tumor Caused by Mycobacteria Infection With Immunoreconstitution Inflammatory Syndrome

Immunoreconstitution inflammatory syndrome (IRIS) was reported to occur in 7-13% of AIDS patients on anti-retroviral therapy (ART). IRIS due to Mycobacterium infection is one of the most difficult IRIS types to manage.

A male patient in his early 70s was diagnosed with AIDS and treated with an ART. One year after starting ART, abdominal ultrasound was performed for screening and a 4 cm hypoechoic mass was found from the outside of the stomach to the surface of the hepatic lateral segment. Based on various imaging tests, including contrast CT, a malignant tumor, such as malignant lymphoma, was suspected. Then, a percutaneous tumor biopsy was performed. Pathologically, the tumor was recognized as mycobacterial granulomas. Disseminated mycobacterium avium complex can produce granulomas anywhere in the body. The patient was diagnosed with a mycobacterial infection associated with IRIS.

When an intra-abdominal mass is found in a patient with HIV, both malignancy and mass formation due to opportunistic infections should be considered differential diseases.

Knowledge and Practice for Prevention of Bovine Tuberculosis and Its Derivers Among HIV Positive People in Bahir Dar City Public Hospitals, Ethiopia

Introduction

Bovine tuberculosis is an important zoonotic disease caused by Mycobacterium bovis, known to exist in all parts of the world especially in un-hygienic environments. It has a public health impact and humans acquire the infection from infected animals through consumption of raw or unpasteurized milk and dairy products.

Methods

An Institutional-based quantitative cross-sectional study was conducted from February to April 2020 to assess the knowledge and practice level along with their derivatives of bovine tuberculosis among adult HIV-positive people in Bahir Dar city public hospitals. The data were collected using structured interviewer questionnaire and systematic random sampling was employed to select study subjects. Thus, a total of 435 people living with HIV were considered for this study.

Results

Out of the total 435 participants 51.5% were male and the mean age was 37.6 years. The overall level of good knowledge and practice of HIV-positive persons for bovine TB were 46.2% and 41.1%, respectively. Moreover, education status, religion, cattle holding, and environmental hygiene were statistically significant associations (p < 0.05) with knowledge level. Likewise, education status, age, and marital status were statistically significant associations with the practice level for bovine TB. Education was a key determinant factor affecting both knowledge and practice.

Conclusion

In conclusion, the present study showed that the level of good knowledge and practice of the participant for bovine TB was low. Hence, tailor-made training by medical and veterinary professionals on the identified risk factors is recommended.

Identification of antigens specific to non-tuberculous mycobacteria: the Mce family of proteins as a target of T cell immune responses

The lack of an effective TB vaccine hinders current efforts in combating the TB pandemic. One theory as to why BCG is less protective in tropical countries is that exposure to non-tuberculous mycobacteria (NTM) reduces BCG efficacy. There are currently several new TB vaccines in clinical trials, and NTM exposure may also be relevant in this context. NTM exposure cannot be accurately evaluated in the absence of specific antigens; those which are known to be present in NTM and absent from M. tuberculosis and BCG. We therefore used a bioinformatic pipeline to define proteins which are present in common NTM and absent from the M. tuberculosis complex, using protein BLAST, TBLASTN and a short sequence protein BLAST to ensure the specificity of this process. We then assessed immune responses to these proteins, in healthy South Africans and in patients from the United Kingdom and United States with documented exposure to NTM. Low level responses were detected to a cluster of proteins from the mammalian cell entry family, and to a cluster of hypothetical proteins, using ex vivo ELISpot and a 6 day proliferation assay. These early findings may provide a basis for characterising exposure to NTM at a population level, which has applications in the field of TB vaccine design as well as in the development of diagnostic tests.

Mycobacterium tuberculosis and nontuberculous mycobacterial isolates among patients with recent HIV infection in Mozambique

OBJECTIVE

Mycobacteriosis is frequently diagnosed among HIV-infected patients. In Mozambique, where few patients are under antiretroviral therapy and the prevalence of tuberculosis is high, there is need for better characterization of mycobacteria at the species level, as well as for the identification of patterns of resistance to antituberculous drugs.

METHODS

We studied a sample of 503 HIV-infected individuals suspected of having pulmonary tuberculosis. Of those 503, 320 tested positive for mycobacteria through sputum smear microscopy or culture of bronchoalveolar lavage fluid.

RESULTS

Acid-fast bacilli were observed in the sputum of 73% of the individuals presenting positive cultures. Of 277 isolates tested, only 3 were nontuberculous mycobacteria: 2 were identified as Mycobacterium avium and one was identified as M. simiae. Strains initially characterized as M. tuberculosis complex through polymerase chain reaction restriction analysis (PRA) of the hsp65 gene were later confirmed as such through PRA of the gyrB gene. Among the M. tuberculosis isolates, resistance patterns were as follows: to isoniazid, 14%; to rifampin, 6%; and multidrug resistance, 5%. Previously treated cases showed significantly higher rates of resistance to first-line antituberculous drugs. The most common radiological pattern was interstitial infiltrate (in 67%), followed by mediastinal lymph node enlargement (in 30%), bronchiectasis (in 28%), miliary nodules (in 18%) and cavitation (in 12%). Patients infected with nontuberculous mycobacteria presented clinical profiles indistinguishable from those of other patients. The median CD4 lymphocyte count in this group was 134 cells/mm(3).

CONCLUSIONS

There is a strong association between tuberculosis and AIDS in Mozambique, as expected in a country with a high prevalence of tuberculosis. Although drug resistance rates are high, the isoniazid-rifampin regimen continues to be the appropriate choice for initial therapy.

Bovine tuberculosis in India: potential basis for zoonosis

Our laboratory has designed a specific nested-PCR (N-PCR) assay, based on the hupB gene of Mycobacterium tuberculosis (Rv2986c) and Mycobacterium bovis (Mb3010c) as a method to differentiate these closely related species. The present paper deciphers the utility of this assay for identification of pathogenic Mycobacteria in clinical samples. Extra-pulmonary clinical samples obtained from cattle and humans were investigated. Pre-dominance of M. tuberculosis (15.7%) and M. bovis (26.8%) was seen in humans and cattle, respectively. However, more importantly, both mycobacterial pathogens (mixed infection) were identified in a number of samples. In humans 8.7% of the samples and 35.7% in cattle were classified as mixed infection. The detection of mixed infection with the mycobacterial pathogenic duo in humans and bovines denotes the prospect of potential transmission of these pathogens from humans to cattle (zoonosis) and vice versa (reverse zoonosis).

Modern laboratory diagnosis of mycobacterial infections

This review summarises recent advances made in microscopic techniques (fluorescence and peptide nucleic acids) and culture techniques (solid, liquid, radiometric, and non-radiometric systems) and in the development of rapid methods for the identification of mycobacterial cultures (high performance liquid chromatography, thin layer chromatography, RNA sequencing, and polymerase chain reaction restriction enzyme assays). The role of molecular amplification systems in identifying Mycobacterium tuberculosis is described. Most methods record high specificity and sensitivity for smear positive sputum but have variable sensitivity for sputum smear negative and extrapulmonary specimens. Specimen quality will affect the performance of these assays and organisational delays, such as the batching of specimens, can reduce the time saved. In house assays can be as effective as commercial systems as long as appropriate controls are used.

Potential source of human exposure to Mycobacterium bovis in Burkina Faso, in the context of the HIV epidemic

OBJECTIVE

To identify potential sources of human Mycobacterium bovis infection in Bobo-Dioulasso, Burkina Faso.

METHODS

A tuberculin survey among 174 cattle was performed. Mycobacteriologic identification in 64 samples of pooled milk, and in 199 tissue samples collected from the slaughterhouse of Bobo-Dioulasso, Burkina Faso, was also done. We retrospectively analyzed the distribution of tuberculosis (TB) cases on 1140 clinical records according to professional occupation and to ethnic group. The frequency of pulmonary and extrapulmonary TB was related to potential exposure and route of transmission of M. bovis from animals.

RESULTS

Out of six herds (total 170 bovines), only one was free of any positive tuberculin test. Among 199 bovines which had been slaughtered over four consecutive nights, 38 (19%) had morphologic lesions suggestive of TB; 17 (45%) of those were positive for acid-fast bacilli by microscopic examination on one of their lesions, and 20 samples (53%) presented a positive culture for a pathogenic mycobacterium, including M. bovis and M. tuberculosis. In the retrospective analysis, Peuls more frequently had a pulmonary form of disease. This may be related to the route of transmission.

CONCLUSIONS

Attention has to be paid to human TB of bovine origin in Burkina Faso. The identification of M. tuberculosis in milk and in tissue samples raises the question of the transmission of TB from humans to cattle.

Zoonotic tuberculosis due to Mycobacterium bovis in developing countries

The World Health Organization (WHO) estimates that human tuberculosis (TB) incidence and deaths for 1990 to 1999 will be 88 million and 30 million, respectively, with most cases in developing countries. Zoonotic TB (caused by Mycobacterium bovis) is present in animals in most developing countries where surveillance and control activities are often inadequate or unavailable; therefore, many epidemiologic and public health aspects of infection remain largely unknown. We review available information on zoonotic TB in developing countries, analyze risk factors that may play a role in the disease, review recent WHO activities, and recommend actions to assess the magnitude of the problem and control the disease in humans and animals.

Detection of Mycobacterium tuberculosis by PCR amplification with pan-Mycobacterium primers and hybridization to an M. tuberculosis-specific probe

Nucleic acid amplification techniques such as the PCR are very useful in the rapid diagnosis of infections by Mycobacterium tuberculosis. However, recent studies have shown that the accuracy of results can vary widely when tests are performed with nonstandardized reagents. We have developed a PCR assay for the detection of M. tuberculosis that is both rapid and accurate. The assay reagents are standardized and quality controlled. False-positive results due to carryover contamination are prevented by the incorporation of dUTP coupled with uracil-N-glycosylase restriction. This assay also employs pan-Mycobacterium amplification primers, allowing for flexibility in the mycobacterial species that can be identified from a single amplification reaction. The amplification is very sensitive; amplification products generated from as few as three bacteria can be detected by agarose gel electrophoresis. DNAs isolated from 33 of 34 mycobacterial species tested were amplified efficiently. Only DNA from Mycobacterium simiae did not amplify. The amplification is also very specific. Amplification products were generated only from the DNAs of bacteria in closely related genera such as Corynebacterium. The nonmycobacterial amplicons do not pose a problem, as they do not hybridize to mycobacterium-specific probes. Hybridization of amplicons to an M. tuberculosis-specific probe allows for the unambiguous identification of M. tuberculosis complex organisms. The clinical performance of this PCR assay was evaluated against that of culture in 662 respiratory specimens. Sensitivities of 100 and 73.1% were obtained from smear-positive and -negative respiratory specimens, respectively. The corresponding specificities were 100 and 99.8%. The high sensitivity and specificity, coupled with the potential for detecting a wide range of mycobacteria, make this assay a useful tool in the clinical management of mycobacterial infections.

AIDS in Africans living in London

OBJECTIVES

To investigate the presentation of HIV infection and AIDS amongst Africans diagnosed with AIDS living in London.

METHODS

Identification of all AIDS cases of African origin attending four HIV specialist centres in South London--Guy's, King's, St George's and St Thomas' Hospitals--up to March 1994, by retrospective review of case notes of all HIV positive patients.

RESULTS

Of 86 patients (53 women, 33 men) studied, 59 (69%) were from Uganda. The most frequent AIDS-defining diagnoses were: Pneumocystis carinii pneumonia (PCP) 21%, tuberculosis (TB) 20% (extrapulmonary TB 14%, pulmonary TB 6%), cerebral toxoplasmosis 14%, oesophageal candida 13%, cryptococcal meningitis 11%, wasting 6%, herpes simplex infection > 1 month 5%, Kaposi's sarcoma 5%, other 6%. Cytomegalovirus retinitis was diagnosed in one case. Late presentation was common; 70% were diagnosed HIV positive when admitted to hospital. The diagnosis of AIDS was coincident with a first positive HIV test result in 61%. The mean CD4 counts at both HIV and AIDS diagnoses were similar in both men and women: 87 x 10(6)/l and 74 x 10(6)/l in men and 99 x 10(6)/l and 93 x 10(6)/l in women respectively. Overall, TB 21 (24%) (extrapulmonary TB 12, pulmonary TB 9) was either the AIDS-defining diagnosis or was detected within three months of this event. Sixty-two per cent of TB cases were diagnosed within twelve months of entry to the UK compared to 34% of all other AIDS cases. The prevalence of STD was very low; genital herpes was the commonest STD: 17% of the women, 9% men; 28% of the men and 11% of the women tested had a positive TPHA test. In cases known to be HIV-positive prior to an AIDS diagnosis, 41% took prophylaxis for PCP and 45% had taken zidovudine (ZDV). Forty two of the study participants had 89 children: 59 of these children had mothers in the study. Overall, 37 (42%) of the children had lost at least one parent at the time of data assessment.

CONCLUSIONS

PCP and TB were the most common initial AIDS-defining diagnoses. The majority of TB cases were diagnosed within 12 months of entry to the UK. An AIDS-defining diagnosis was the first manifestation of HIV-related illness in the majority of patients. Because of late presentation to medical services, access to treatments for HIV infection and prophylaxis against opportunistic infections was limited. Extending the role of clinics and staff into the community might facilitate both earlier presentation and access to services. Future provision of local services will need to be sensitive to the requirements of individuals from different cultures and backgrounds.

Bacteriologically confirmed non-tuberculous mycobacterial lymphadenitis in south east England: a recent increase in the number of cases

The annual numbers of cases of non-tuberculous mycobacterial lymphadenitis in south east England has increased over the period 1973 to 1993, most notably during the last few years. The most frequent cause is the Mycobacterium avium complex, followed by M malmoense. The reason for the increase is unknown but it could be due to an increased awareness in mycobacterial disease, an external factor such as pollution, or both.