Molecular Identification of Nontuberculous Mycobacteria in Humans in Zimbabwe Using 16S Ribosequencing

BACKGROUND: Several nontuberculous mycobacteria (NTM) were previously isolated from diverse environments such as water, soil, sewage, food and animals. Some of these NTM are now known to be opportunistic pathogens of humans. OBJECTIVE: The main purpose of the study was to identify NTM isolates stored at the National Microbiology Reference Laboratory (NMRL) and were previously isolated from humans during a national tuberculosis (TB) survey. METHODS: Pure NTM cultures already isolated from human sputum samples during the national TB survey were retrieved from the NMRL and used for this study. DNA was extracted from the samples and 16S ribosomal RNA gene amplified by polymerase chain reaction. The amplicons were sequenced and bioinformatics tools were used to identify the NTM species. RESULTS: Out of total of 963 NTM isolates stored at the NMRL, 81 were retrieved for speciation. Forty isolates (49.4%) were found to belong to Mycobacterium avium-intracellulare complex (MAC) species. The other 41 isolates (50.6%) were identified as M. lentiflavum (6.2%), M. terrae complex (4.9%), M. paraense (4.9%), M. kansasii (3.7%), M. moriokaense (3.7%), M. asiaticum (2.5%), M. novocastrense (2.5%), M. brasiliensis (2.5%), M. elephantis (2.5%), M. paraffinicum (1.2%), M. bohemicum (1.2%), M. manitobense (1.2%), M. intermedium (1.2%), M. tuberculosis complex (1.2%), M. parakoreense (1.2%), M. florentinum (1.2%), M. litorale (1.2%), M. fluoranthenivorans (1.2%), M. sherrisii (1.2%), M. fortuitum (1.2%) and M septicum (1.2%). Two isolates (2.5%) could not be identified, but were closely related to M. montefiorense and M. phlei respectively. Interestingly, the MAC species were the commonest NTM during the survey. CONCLUSION: The study emphasizes the importance of identifying species of NTM in Zimbabwe. Future studies need to ascertain their true diversity and clinical relevance

Experimental Germ Tube Induction in Candida albicans: An Evaluation of the Effect of Sodium Bicarbonate on Morphogenesis and Comparison with Pooled Human Serum

Objective. The potential of NaHCO3 versus human serum to induce germ tube formation in Candida albicans was investigated. Specimens. A total of 100 isolates were obtained from oral swabs of patients presenting with thrush. Approval for the study was granted by the Joint Research Ethics Committee (JREC/23/08). Method. Confirmed C. albicans isolates by routine methods were tested for germ tube induction using 5 different concentrations of Tris-maleate buffered NaHCO3 and Tris-maleate buffer control. Standard control strains included were C. albicans (ATCC 10231) and C. krusei (ATCC 6258). Microculture was done in 20 μL inoculums on microscope slides for 3 hours at 37°C. The rate of germ tube formation at 10-minute intervals was determined on 100 isolates using the optimum 20 mM Tris-maleate buffered NaHCO3 concentration. Parallel germ tube formation using human serum was done in test tubes. Results. The optimum concentration of NaHCO3 in Tris-maleate buffer for germ tube induction was 20 mM for 67% of isolates. Only 21% of isolates formed germ tubes in Tris-maleate buffer control. There was no significant difference in induction between human serum and Tris-maleate buffered NaHCO3. Conclusion. Tris-maleate buffered NaHCO3 induced germ tube formation in C. albicans isolates at rates similar to human serum

Human parasitic protozoa in drinking water sources in rural Zimbabwe and their link to HIV infection

OBJECTIVE: We aimed to perform a risk assessment in a rural setting, where drinking water is obtained from both protected and unprotected deep or shallow wells, boreholes and springs. Water is consumed untreated and this poses a risk of acquiring waterborne infections that may cause diarrhea. METHODS: The study included 113 study participants who volunteered in Chiweshe rural community (Musarara village) in Mashonaland Central Province in Zimbabwe. There were 34 (30%) males and 79 (70%) females with ages ranging from 2 to 89 years. HIV counseling was carried out at the communal meeting and testing was done at home visits. Stool and drinking water samples were collected from 104 subjects. Routine laboratory methods were used to examine for parasitic infections. RESULTS: Only 29 (25.7%) of participants were confirmed HIV positive using 2 rapid serology tests; eighty-four (74.3%) were negative. Diarrheic stool samples were observed in 17 (16.3%) participants and of these 5 (29.4%) were HIV seropositive. Several parasites were isolated from stool samples: G. duodenalis 6 (5.7%), E. histolytica/dispar 19 (18.2%), C. parvum, 8 (7.6%) and C. cayetanensis 23 (22.1%). Eleven out of 30 (36.6%) water bodies had protozoan parasites: G. duodenalis 2 (6.6%), E. histolytica 4 (13.3%), C. parvum 1 (3.3%), C. cayetanensis 3 (10%), E. coli 1 (3.3%). CONCLUSION: The water sources were being used without treatment and were shown to pose a risk for acquiring diarrheagenic protozoan parasites