Resistance to First-Line Anti-TB Drugs Is Associated with Reduced Nitric Oxide Susceptibility in Mycobacterium tuberculosis

Background and objective: The relative contribution of nitric oxide (NO) to the killing of Mycobacterium tuberculosis in human tuberculosis (TB) is controversial, although this has been firmly established in rodents. Studies have demonstrated that clinical strains of M. tuberculosis differ in susceptibility to NO, but how this correlates to drug resistance and clinical outcome is not known. Methods: In this study, 50 sputum smear- and culture-positive patients with pulmonary TB in Gondar, Ethiopia were included. Clinical parameters were recorded and drug susceptibility profile and spoligotyping patterns were investigated. NO susceptibility was studied by exposing the strains to the NO donor DETA/NO. Results: Clinical isolates of M. tuberculosis showed a dose- and time-dependent response when exposed to NO. The most frequent spoligotypes found were CAS1-Delhi and T3_ETH in a total of nine known spoligotypes and four orphan patterns. There was a significant association between reduced susceptibility to NO (>10% survival after exposure to 1mM DETA/NO) and resistance against first-line anti-TB drugs, in particular isoniazid (INH). Patients infected with strains of M. tuberculosis with reduced susceptibility to NO showed no difference in cure rate or other clinical parameters, but a tendency towards lower rate of weight gain after two months of treatment. Conclusion: There is a correlation between resistance to first-line anti-TB drugs and reduced NO susceptibility in clinical strains of M. tuberculosis. Further studies including the mechanisms of reduced NO susceptibility are warranted and could identify targets for new therapeutic interventions

Isolation and Characterization of Lactic Acid Bacteria from Fermented Milk Produced in Jimma Town, Southwest Ethiopia, and Evaluation of their Antimicrobial Activity against Selected Pathogenic Bacteria

Background. Raw milk is usually contaminated with pathogenic bacteria. Fermentation of milk is important to inhibit the growth of contaminants, spoilage, and pathogenic bacteria. The objective of this study was to isolate lactic acid bacteria from fermented milk and evaluate their antimicrobial activity against selected pathogenic bacteria. Methods. Laboratory-based experimental study design was conducted from May-July, 2021.Three samples of Ergo (each of 250 ml) were collected from Jimma town. Lactic acid bacteria (LAB) isolates were identified through integrated phenotypic techniques. Further identification was conducted through using API 50 CHL strips. Antimicrobial activities (AMAs) of LAB isolates were tested against clinical isolates of E. coli, S. aureus, and Salmonella spp. using agar well diffusion method. The data were analyzed by using SPSS software version 21 and Microsoft Excel spreadsheet. Tables and figures were applied to describe characteristics of data. Results. Twelve LAB isolates were identified. Those LAB isolates include six Lactococcus lactis subsp. lactis, Lactobacillus acidophilus (2), Lactiplantibacillus plantarum (1), Limosilactobacillus fermentum (2), and Leuconostoc lactis (1). Based on primary screening of LAB, isolates/strains ESCIa, ESBIa, and ESCIc show strong AMA against S. aureus, E. coli, and Salmonella spp. The CFS of ESCIc showed the highest AMA against S. aureus and Salmonella spp. with a zone of inhibition of 14.12±1.6 mm and 12.9±3.6 mm, respectively, while ESBIa showed the highest AMA against E. coli with a zone of inhibition of 13.5±2.1 mm. The CFSs of selected LAB strains were heat tolerant at varying temperatures up to 100°C. The CFSs of selected LAB strains were inactivated by proteinase enzymes, but they are not inactivated with amylase enzymes. Conclusions and Recommendation. All 12 LAB isolates exhibited antimicrobial activity against tested bacterial strains. Lactobacillus isolates showed the highest antagonistic activity on tested indicator strains. Thus, they are possible alternatives to antibiotics in the era of antimicrobial resistance. S. aureus was the most sensitive to antimicrobial effects/agents of selected LAB isolates. Consumption of fermented foods is advisable since they support the growth of healthy GIT microbiota. Fermentation serves as biopreservation of food. However, analysis of probiotic features and in vivo probiotic effects of those LAB isolates will be subject of future research/study

Uropathogenic bacterial profile and antibiotic susceptibility pattern of isolates among gynecological cases admitted to Jimma Medical Center, South West Ethiopia

Abstract Urinary tract infection (UTI) is one of the most common bacterial infections in women; about 50% of women get during their life time. Moreover, it is a common health problem in patients with gynecological pathologies, which increases the chance of acquiring infection. The aim of this study was to determine the bacterial profile that causes UTI and their antibiotic susceptibility pattern among admitted gynecological cases. A cross-sectional study was conducted in south west Ethiopia region. A total of 386 patients admitted with gynecological cases were recruited by sequential sampling technique and structured questionnaire was used to collect socio-demographic and risk factor-related data. About 10 ml freshly voided midstream and catheterized urine specimens were collected using sterile containers. Identification of isolate was done using culture characteristics, gram staining, and a series of biochemical tests. The antibiotic susceptibility test was performed as per the Kirby–Bauer disc diffusion technique. The data obtained were entered into EpiData Version 3.1 and analyzed using SPSS Version 25. A P value of less than 0.05 was used as a level of significance. In this study, the overall prevalence of UTI was 25.4%. Escherichia coli was the most frequently isolated bacteria, which accounted for 38 (37.6%), followed by Klebsiella species 22 (21.8%), CONS 14 (13.9%), Staphylococcus aureus 10 (9.9%), Enterobacter species 6 (5.9%), Citrobacter species 5 (4.9%), Proteus mirabilis 4 (4%), and Pseudomonas aeroginosa 2(2%). Histories of UTI (AOR = 1.977, 95% CI 1.06, 3.68, P = 0.032) and catheterization (AOR = 2.38, 95% CI 1.28, 4.45, P = 0.006) were found to be statistically associated with significant bacteriuria. Gram-negative isolates showed a high level of resistance, 88.3% for ampicillin and 66.2% for tetracycline, and a relatively low level of resistance against ceftazidime, 22.1%, and meropenem, 3.9%. Gram-positive uropathogens showed a high level of resistance to penicillin, 91.6%, whereas all isolates were sensitive 100.0% to nitrofurantoin. Furthermore, 80 (79.2%) of the isolates had multidrug resistance, and 16 (26.7%) of both E. coli and Klebsiella spp. produced Extended spectrum β-lactamase (ESBL). In this study, a high prevalence of uropathogenic bacteria and multidrug resistance for commonly prescribed drugs were observed with a significant number of ESBL producers. Therefore, screening admitted gynecological patients, especially for those who have history of catheterization and UTI, by urine culture and antimicrobial susceptibility testing is important

Resistance to pyrazinamide in Mycobacterium tuberculosis complex isolates from previously treated tuberculosis cases in Southwestern Oromia, Ethiopia

Objective: Pyrazinamide (PZA) susceptibility testing is important to develop evidence-based algorithms for case management. We aimed to assess the prevalence of PZA-resistance and its impact on treatment outcomes in previously treated tuberculosis (TB) cases in southwestern Oromia, Ethiopia. Methods: A Phenotypic Drug Susceptibility Testing (DST) of PZA with BACTEC MGIT 960 was conducted at the Mycobacteriology Research Center of Jimma University (MRC-JU) from June to November 2021 on sixty-six Mycobacterium tuberculosis complex (MTBC) isolates from previously treated TB cases. SPSS software package version 21 was used. The differences in the proportion of PZA resistance between the groups were compared using the chi squared test. Logistic regression was used to identify the association between PZA resistance and treatment outcomes. Results: Among 66 MTBC isolates (49 rifampicin-resistant and 17 rifampicin-sensitive) included in this study, 31.8 % were resistant to PZA. The proportion of PZA resistance was almost three times higher in previously treated TB cases with rifampicin resistance than in rifampicin-sensitive patients (38.8 % vs. 11.8 %, p = 0.039). An unfavorable treatment outcome was documented for 23 % (15/65) of the participants. Patients with PZA resistance were almost four times more likely to have an unfavorable treatment outcome than patients with PZA sensitive (aOR 4.2, 95 % CI: 1.13–15.3). Conclusions: The prevalence of PZA resistance was high compared to the pooled PZA resistance estimated worldwide. The majority of TB cases with PZA resistance had an unfavorable treatment outcome. PZA susceptibility testing should be included in the multidrug-resistant TB diagnostic algorithm to improve management of these patients

Reduced NO susceptibility in spoligotype-based clusters of <i>M. tuberculosis</i>.

<p>Survival of clinical isolates 24 hours after exposure to the NO donor DETA/NO. Presence of resistance to first-line anti-TB drugs is indicated with circles; isoniazid (INH), streptomycin (SM) and rifampin (RIF). Each point represents a mean value of duplicates and the dashed line is the median survival of all 50 isolates.</p

Characteristics for patients infected with strains of <i>M. tuberculosis</i> susceptible to NO or with reduced susceptibility to NO.

<p>Q1–Q3 (quartile 1 to quartile 3); NO (nitric oxide); BMI (body mass index); ESR (sedimentation rate); INH (isoniazid); SM (streptomycin); EMB (ethambutol); RIF (rifampin). NO-susceptible and reduced NO-susceptible strains defined as ≤10% and >10% survival respectively after exposure to 1 mM DETA/NO. All patients were smear positive at week 0. Continuous data were tested with Mann-Whitney <i>U</i>-test and discrete data with Fisher’s exact test or Pearson’s Chi-square test.</p

Dose- and time-dependent killing of <i>M. tuberculosis</i> exposed to NO.

<p>Survival of three clinical strains, H37Rv and BCG after exposure to 1 mM of the NO donor DETA/NO for 4 and 24 hours (A). Survival of the three clinical strains exposed to different doses of DETA/NO for 24 hours (B). Survival was determined through viable count (colony forming units, CFU) and each point represents a mean value of duplicates.</p

Multiple logistic regression analysis comparing strains of <i>M. tuberculosis</i> susceptible to NO with strains of reduced susceptibility to NO.

<p>Multiple logistic regression analysis comparing strains of <i>M. tuberculosis</i> susceptible to NO with strains of reduced susceptibility to NO.</p

http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-77129 Resistance to First-Line Anti-TB Drugs Is Associated with Reduced Nitric Oxide Susceptibility in Mycobacterium

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