Mycobaterium Tuberculosis Infection in Northeastern Ethiopia: Studies on the Molecular Epidemiology, Drug Sensitivity Profile, Nutritional Status and Parasitosis Co-Infection as Major Risk Factors

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Date

2020-07-07

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Addis Ababa University

Abstract

Background: Ethiopia stands 12th among the 30 high TB burden countries with incidence rate of 165 cases per 100,000 population.Continuousand sustainable efforts should be exerted in different aspects including in research in order to reduce the burden of TB in the country. Objective: The present study was conducted in northeastern Ethiopia to investigate the nutritional status of TB patients, TB co-infection with parasites, the types strains of M. tuberculosis circulating in the area and evaluate the drug sensitivity profiles the strains. Methods:A cross-sectional study was conducted on 384 TB patients (286 smear positive pulmonary TB and 98 extra-pulmonary TB cases) who were visiting health care institution for seeking treatment. Anthropometric measurements were used for the assessment of the nutritional status of TB patients while direct wet mount microscopy, Kato-Katz and concentration techniques were used stool examination for parasite co-infections. Clinical examination, ZiehlNeelsen staining, mycobacterial culture, region of difference (RD) 9-based polymerase chain reaction (PCR), spoligotyping and mycobacterial interspersed repetitive unit-variable-number tandem repeat (MIRU-VNTR) typing were used TB investigation. In addition, Mycobacteria Growth Indicator Tube (MGIT) test and GenoTypic MTBDRplus assay were used to evaluate drug sensitivity profiles of M. tuberculosis.Data were analyzed using descriptive statistics and Pearson chi-square. Results: The prevalence of undernutrition was 58.6% using body mass index while it was 73.0% using mid-upper arm circumference. The overall prevalence of TB-parasitosis co-infection was 10.8%; intestinal helminths co-infection was 9.7% while intestinal protozoa co-infection was 1.9%. Clinically, TB lymphadentis accounted for 85.9% of the extra-pulmonary TB of which cervical lymphadenopathy was 75.3%. Culture positivity was confirmed in only 29.2% (112/384). Speciation of the isolates using RD9 PCR revealed 77.7% of the isolates were M. tuberculosis. But no signal was detected for the remaining 22.3% (25/112) isolates. Spoligotyping of 112 identified 92.9% (104/112) as interpretable spoligotyping patterns. Twenty-one percent of the isolates were grouped under 10 clustered strains while the remaining 79% (n=83) isolates were classified as singleton strains. On the other hand, 13.5% of the isolates were grouped under shared types and 86.5% were orphan. Furthermore, spoligotyping grouped 52.9%, 27.9% and 19.2% of the isolates in Euroamerican, Indio-oceanic and East African Indian lineages, respectively. DNA samples of 69 isolates were tested by 24-loci MIRU-VNTR typing and 56 had valid amplification products while the remaining 13 isolates had either incomplete or negative results. Each of the 56 isolates had distinct MIRU-VNTR profile and as a result, 56 different genotypes (strains) were detected MIRU-VNTR typing. The results of MGIT and MTBDRplus assay showed that 15.9% and 16.8% of the isolates developed resistance to either of the first line anti-TB drugs, respectively. The percentage of multi-drug resistance (MDR) M. tuberculosis was 8.4% (8/95) as detected by GenoTypic MTBDRplus assay. The agreement between MGIT and MTBDRplus assay in detecting resistance to Isoniazid (INH) was substantial (k=0.77) while it was near perfect in detecting either resistance to Rifampicin (RIF) (k=0.93) or in detecting MDR M. tuberculosis (k=0.90). Conclusion: Undernutrition and co-infection with parasites were common in TB patients in northeastern Ethiopia. The strains M. tuberculosis circulating in northeastern Ethiopia were highly diverse and a significant proportion of the strains have developed drug resistance. Therefore, improvement of the nutrition and regular de-worming of the population in the area would contribute significantly to reduction of the burden TB and improves the response to TB treatment. Additionally, public education is required on the proper use of anti-TB drugs. Furthermore, special attention should be given to MDR TB cases so that their further transmission is contained.

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Keywords

Mycobacterium Tuberculosis, Molecular Typing, Drug Sensitivity, Parasite Co-Infection, Undernutrition, Northeastern Ethiopia

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