Ziehl-Neelsen microscopy in the diagnosis of tuberculosis in settings of high human immunodeficiency virus prevalence

Objective: To determine the accuracy of Ziehl-Neelsen microscopy in the diagnosis of TB in setings of high HIV prevalence.Design: Cross-sectional descriptive study.Setting: Hospitals serving areas of high human immunodeficiency virus prevalence in western Kenya. The study was conducted between September 2007 and September 2009.Results: In total, 341/872 (39.1%) of the TB suspects were positive in ZN, 53.1% (181/341) of them culture positive. Only 3.8% (20/531) of the ZN smear negatives were culture positive. Of the 695 suspects evaluated for both Mycobacterium and HIV infection, 255 (36.7%) were ZN smear positive, 42.7% of them HIV positive. Out of the 440 ZN smear negatives, 37% were HIV positive. Similarly, 168 suspects were culture positive, 46.4% of them HIV positive. The HIV infection did not significantly reduce ZN smear positivity rate (P = 0.42) and culture sensitivity (P = 0.09). The ZN sensitivity and specificity were 88.1% and 79.7%, respectively. The predictive values were 58.0 (PPV), and 95.5% (NPV), respectively. However, the area under the ROC curve was 0.84, with 95% CI between 0.80-0.87 and P< 0.001). The ZN smear microscopy had a lesser ability to distinguish between TB and non-TB cases compared to culture.Conclusion: ZN microscopy causes a significant over-diagnosis of TB in settings of high HIV/AIDS prevalence. There is need for further studies on this subject taking into consideration the various confounding factors

Misdiagnosis and clinical significance of non-tuberculous mycobacteria in Western Kenya in the era of human immunodeficiency virus epidemic

Objectives: To determine and document the role of non-tuberculous mycobacteria (NTM) in TB-like disease morbidity and demonstrate the confusion they cause in the diagnosis of TB in western Kenya.Design: A cross-sectional study.Setting: One provincial and nine District hospitals in western Kenya.Subjects: Tuberculosis suspects.Interventions: Sputa from 872 tuberculosis suspects underwent microscopy and culture on solid and liquid media. The growth was identified using the Hain’s GenoType® Mycobacterium CM and GenoType® Mycobacterium AS kits. Consenting clients were screened for HIV infection using Trinity Biotech Uni-GoldTM test and positive cases were confirmed with the enzyme linked immunosorbent assay. A questionnaire was used to obtain demographic data.Main outcome measures: ZN smear positivity / negativity; Culture positivity or negativity; Mycobacterium species isolates (tuberculous or non-tuberculous); HIV status.                                                      Results: Sputa from 39.1% (341/872) of the participants were ZN smear positive, of these 53.1% (181/341) were culture positive. Only 3.8% (20/531) of the ZN smear negatives were culture positive. In total 41.4% (361/872) participants were infected with mycobacteria, of which 44.3% (160/361) were culture negative and 55.7% (201/361) were culture positive. The culture positives yielded 92.5% M. tuberculosis complexand 7.5% NTM. The overall prevalence of the NTM disease was 1.72% (15/872).                                                                            Conclusion: A low prevalence of NT M pulmonary disease in western Kenya is reported in this study, but some the NTM disease cases could have been misdiagnosed as TB cases

Webuye health and demographic surveillance systems baseline survey of soil-transmitted helmints and intestinal protozoa among children up to five years

Background. The intestinal parasitic infections (IPIs) are globally endemic, and they constitute the greatest cause of illness and disease worldwide. Transmission of IPIs occurs as a result of inadequate sanitation, inaccessibility to potable water, and poor living conditions. Objectives. To determine a baseline prevalence of IPIs among children of five years and below at Webuye Health and Demographic Surveillance (HDSS) area in western Kenya. Methods. Cross-sectional survey was used to collect data. Direct saline and formal-ether-sedimentation techniques were used to process the specimens. Descriptive and inferential statistics such as Chi-square statistics were used to analyze the data. Results. A prevalence of 52.3% (417/797) was obtained with the male child slightly more infected than the female (53.5% versus 51%), but this was not significant (χ2=0.482, P>0.05). Giardia lamblia and Entamoeba histolytica were the most common pathogenic IPIs with a prevalence of 26.1% (208/797) and 11.2% (89/797), respectively. Soil-transmitted helminths (STHs) were less common with a prevalence of 4.8% (38/797), 3.8% (30/797), and 0.13% (1/797) for Ascaris lumbricoides, hookworms, and Trichuris trichiura, respectively. Conclusions. Giardia lamblia and E. histolytica were the most prevalent pathogenic intestinal protozoa, while STHs were less common. Community-based health promotion techniques are recommended for controlling these parasites

HIV co-infection with tuberculous and non-tuberculous mycobacteria in western Kenya: challenges in the diagnosis and management

Background: Tuberculosis (TB) and HIV co-infections have a global prevalence with devastating morbidity and massive mortality, Sub-Saharan Africa being the worst hit.Objectives: To evaluate the prevalence of TB-HIV co-infection and demonstrate the confusion caused by NTM and HIV/AIDS co-infection in TB diagnosis and treatment in western Kenya.Methods: In a cross-sectional study carried out at 10 hospitals in western Kenya, sputa from consenting 872 TB suspects underwent microscopy, and culture on Lowenstein-Jensen and Mycobacteria Growth Index Tube media. Isolates were identified using the Hain’s GenoType® Mycobacterium CM and GenoType® Mycobacterium AS kits. A total of 695 participants were screened for HIV using Uni-GoldTM test and positives confirmed with the enzyme linked immunosorbent assay.Results: A total of 346 (39.7%) participants were diagnosed with TB. Out of the 346 TB cases, 263 (76%) were tested for HIV infection and 110 (41.8%) of these were sero-positive (co-infected). The female to male TB-HIV co-infection prevalence ratio (PR) was 1.35. This study reports isolation of non-tuberculous mycobacteria from TB suspects at a rate of 1.7%.Conclusion: A high TB-HIV co-infection rate was observed in this study. The NTM disease could be misdiagnosed and treated as TB in western Kenya.Key words: Tuberculosis, HIV co-infection, high prevalence, TB diagnosi

Species diversity of non-tuberculous mycobacteria isolated from humans, livestock and wildlife in the Serengeti ecosystem, Tanzania.

BACKGROUND: Non-tuberculous mycobacteria (NTM), which are ubiquitous micro-organisms occurring in humans, animals and the environment, sometimes receive public health and veterinary attention as opportunistic disease-causing agents. In Tanzania, there is limited information regarding the diversity of NTM species, particularly at the human-livestock-wildlife interface such as the Serengeti ecosystem, where potential for cross species infection or transmission may exist. METHODS: Mycobacterial DNA was extracted from cultured isolates obtained from sputum samples of 472 suspect TB patients and 606 tissues from wildlife species and indigenous cattle. Multiplex PCR was used to differentiate NTM from Mycobacterium tuberculosis complex (MTBC) members. NTM were further identified to species level by nucleotide sequencing of the 16S rRNA gene. RESULTS: A total of fifty five (55) NTM isolates representing 16 mycobacterial species and 5 isolates belonging to the MTBC were detected. Overall, Mycobacterium intracellulare which was isolated from human, cattle and wildlife, was the most frequently isolated species (20 isolates, 36.4%) followed by M. lentiflavum (11 isolates, 20%), M. fortuitum (4 isolates, 7.3%) and M. chelonae-abscessus group (3 isolates, 5.5%). In terms of hosts, 36 isolates were from cattle and 12 from humans, the balance being found in various wildlife species. CONCLUSION: This study reveals a diversity of NTM species in the Serengeti ecosystem, some of which have potential for causing disease in animals and humans. The isolation of NTM from tuberculosis-like lesions in the absence of MTBC calls for further research to elucidate their actual role in causing disease. We are also suggesting a one health approach in identifying risk factors for and possible transmission mechanisms of the NTM in the agro-pastoral communities in the Serengeti ecosystem