Risk factors for treatment failure in multidrug resistant tuberculosis in Tunisia: An analytic study.

INTRODUCTION-AIM: The emergence of multidrug resistant tuberculosis (MDR-TB) is a threat to global public health. The aim of our study was to determine risk factors for treatment failure in MDR-TB. METHODS: Retrospective study conducted between January 2000 and March 2019 including patients with MDR-TB. Characteristics of patients with therapeutic failure were compared to cured ones. Logistic regression analysis was used to identify risk factors for treatment failure. RESULTS: Our study included 140 patients aged of 42±13 years (18-80). Fifty-seven percent of patients had treatment success and 12% had treatment failure. In multivariate logistic regression analysis, treatment failure was associated with age over 45 years (OR=1.05; 95%CI, 1.024-7.736;p=0.014), primary education level and illiteracy (OR=5.022; 95%CI, 1.316-19.161;p=0,018), history of incarceration (OR=3.291; 95%CI, 1.291-21.083;p=0.016), undernutrition (OR=4.544; 95%CI, 2.304-54.231;p=0,027), extensive TB (OR=6.406; 95%CI, 1.761-23.922; p=0.038), initial high grade positive smears (OR=1.210; 95%CI, 1.187-32.657; p=0.045), positive smear culture at 90 days of treatment (OR=6.871, 95%CI, 3.824-23.541; p=0.003), poor adherence (OR=6.110; 95%CI, 2.740-12.450; p=0.021) and occurrence of psychiatric adverse events (OR=3.644 95%CI, 2.560- 27.268; p=0.041). CONCLUSION: Therapeutic education, nutritional and psychological support and close follow-up are strongly recommended to optimize the prognosis of MDR-TB.

A first insight into genetic diversity of Mycobacterium bovis isolated from extrapulmonary tuberculosis patients in South Tunisia assessed by spoligotyping and MIRU VNTR.

INTRODUCTION: In Tunisia, almost 77% of clinically and bacteriologically diagnosed cases of extrapulmonary tuberculosis (EPTB) are zoonotic TB, caused by M. bovis. Although several studies have analyzed bovine TB in cattle in Tunisia, no study has evaluated the risk of transmission to humans in such an endemic country. We aimed to study the genetic diversity of M. bovis human isolates, to ascertain the causes of human EPTB infection by M. bovis and to investigate the distribution and population structure of this species in Tunisia. MATERIALS AND METHODS: A total of 110 M. bovis isolates taken from patients with confirmed EPTB were characterized by spoligotyping and MIRU-VNTR typing methods. RESULTS: Among the 15 spoligotypes detected in our study, 6 (SB0120, SB0121, SB2025, SB1200, SB1003 and SB0134) were the most prevalent (83.5%) of which SB0120, SB0121 and SB2025 were the most prevailing. MIRU-VNTR typing method showed a high genotypic and genetic diversity. The genetic differentiation based on MIRU-VNTR was significant between populations from South East (Tataouine, Medenine) and Central West (Gafsa, Sidi Bouzid, Kasserine) regions. Of note, 13/15 (86.7%) spoligotypes detected in our study were previously identified in cattle in Tunisia with different frequencies suggesting a peculiar ability of some genotypes to infect humans. Using combined spoligotyping and MIRU-VNTR method, a high clustering rate of 43.9% was obtained. Our results underlined that human EPTB due to M. bovis was more commonly found in female gender and in young patients. Most of our patients, 66.4% (73/110) were raw milk or derivatives consumers, whereas 30.9% (34/110) patients would have contracted EPTB through contact with livestock. The findings suggest that the transmission of Zoonotic TB caused by M. bovis to humans mainly occurred by oral route through raw milk or derivatives. CONCLUSION: Our study showed the urgent need of a better veterinary control with the implementation of effective and comprehensive strategies in order to reach a good protection of animals as well as human health.

First-time detection and identification of the Mycobacterium tuberculosis Complex members in extrapulmonary tuberculosis clinical samples in south Tunisia by a single tube tetraplex real-time PCR assay.

INTRODUCTION: Tunisia has one of the highest burdens of extrapulmonary tuberculosis (EPTB) among tuberculosis (TB) cases but the contribution of MTBC-mediated human EPTB is unknown. EPTB diagnosis is challenging due to the paucibacillary nature of clinical samples. Therefore, a need of a simplified molecular method for sensitive and specific TB detection and differentiation of MTBC members caused EPTB remains a priority to an early diagnosis, optimize successful anti-TB treatment and minimize transmission. We evaluated the performance of a single tube tetraplex Taq Man real time PCR for EPTB detection and differentiation between MTBC members directly on extrapulmonary samples. MATERIALS AND METHODS: Extrapulmonary samples obtained from clinically suspected EPTB patients from 2013 to April 2015 were tested by Ziehl Neelsen Staining, mycobacterial culture and qPCR assay for RD1, RD9, RD12 and ext-RD9 targets (MTBC-RD qPCR). The performance of qPCR was compared to a reference standard based on MTBC culture and/or at least two criteria of a composite reference standard (CRS) including clinical, radiological, histopathological and therapeutic findings. RESULTS: EPTB was identified in 157/170 (92.4%) of included patients of whom 99 (63%) were confirmed by culture and 58 (36.9%) by CRS criteria. The sensitivity and specificity of qPCR, in comparison to the reference standard were 100% (157/157) and 92.3% (12/13), respectively. The sensitivity of qPCR was statistically significant as compared to culture and smear microscopy (P< 0.001). QPCR results showed M. bovis identification in 77.1% of extrapulmonary samples in occurrence to lymphadenitis infection. M. tuberculosis and M.bovis BCG were detected in 21.6% and 1.3% of cases, respectively. CONCLUSIONS: MTBC-RD qPCR proved to be a rapid and sensitive assay for simultaneously TB detection and MTBC members identification on extrapulmonary samples within 1.5 days after sample receipt. Its high sensitivity could make this method a useful tool in diagnosing TB in addition to routine conventional methods and TB clinical parameters.

Molecular characterization of Mycobacterium tuberculosis strains resistant to isoniazid.

OBJECTIVE/BACKGROUND: Tuberculosis is a major public health problem and the emergence of drug resistance complicates the situation even more. It is therefore crucial to implement all conclusions from the studies that aim at a better understanding of the molecular mechanisms which govern the emergence and the evolution of drug resistance. The aim of this study is to assess the degree of involvement of the inhA and katG genes in the acquisition of isoniazid resistance in clinical strains of Mycobacterium tuberculosis. METHODS: The inhA and katG genes were sequenced in 21 strains of M. tuberculosis with different resistance profiles and from different regions. RESULTS: Analysis of the sequences obtained by comparison to those of the reference strain H37Rv showed that 95.2% had mutations. KatG S315T was the most common mutation (85.7%). The mutation katG T275A was revealed in two strains (9.5%). Two different point mutations in the inhA gene and its promoter region were identified as C-15T and G56A at a frequency equal to 14% and 10%, respectively. The G56A mutation is a new silent mutation. Our study showed no correlation between found mutations and multidrug resistance. Among the 21 strains studied, only one strain showed no mutations. CONCLUSION: In terms of this study, we characterized the mutations involved in resistance to isoniazid. katG S315T was by far the most frequent mutation, followed by C-15T. The frequency of these mutations was concordant with those reported in literature including those in intermediate tuberculosis endemic countries.

Drug susceptibility testing of Mycobacterium tuberculosis by a nitrate reductase assay applied directly on microscopy-positive sputum samples.

AIMS AND OBJECTIVES: Current methods for drug susceptibility testing (DST) of Mycobacterium tuberculosis (MTB) are either costly or slow. As the prevalence of multidrug-resistant (MDR) strains increases, the need for fast, reliable, and inexpensive methods is obvious. This study evaluated a rapid colorimetric nitrate reductase assay (NRA) for direct DST of MTB directly from clinical sputum samples. METHODS: A total of 111 sputa with positive microscopy results for acid-fast bacilli (AFB) with more than 10 AFB per high-power field were used in the study. The samples were decontaminated using the modified Petroff method. The NRA results were compared with the reference indirect proportion method. RESULTS: The sensitivity and the specificity of the direct NRA were 90% and 97.3%, 92.6% and 98.2%, 52.9% and 100%, and 28.6% and 100% for rifampin, isoniazid, streptomycin, and ethambutol, respectively. The results were in most cases available in 28days (84.3%). CONCLUSIONS: The direct NRA could be used as a rapid, inexpensive, and accurate method to determine rifampin and isoniazid susceptibility directly from sputum. The technique might become a valid alternative to traditional methods, especially in low-income countries.

[Pulmonary tuberculosis and diabetes. A retrospective study of 60 patients in Tunisia]. / La tuberculose pulmonaire provoque un déséquilibre du diabète Etude rétrospective de 60 malades en Tunisie.

BACKGROUND: Tuberculosis is a frequent infectious disease in Tunisia. The estimated case rate is 22.3 per 100,000 inhabitants. The risk of tuberculosis is 2 to 6 times greater in patients with diabetes. The purpose of this study was to analyze the particularities in the etiology, diagnosis and bacteriologic course of pulmonary tuberculosis in patients with diabetes and to evaluate the impact of tuberculosis on diabetes control. METHOD: This retrospective case-control study of 142 patients with confirmed pulmonary tuberculosis seen from 2000-2006 compared the 60 patients with diabetes with the 82 without diabetes. RESULTS: Diabetes was more frequent in older patients with tuberculosis and in women. 91.5% had type 2 diabetes. A history of contact with people with tuberculosis was significantly less frequent in the group with diabetes (13.3% vs 30.5%; p=0.01). Tuberculosis symptoms and their duration did not differ between the 2 groups. Basal lesions and cavitation occurred more frequently in the patients with diabetes, but this difference was not significant. The time for conversion to negative of sputum culture was longer in case patients (43+/-27 days) than in controls (28.2+/-20.5) (p=0.03). The proportion of patients with uncontrolled diabetes was elevated, and 50% required frequent insulin treatment. CONCLUSION: Tuberculosis is frequently associated with diabetes, usually due to reactivation of Mycobacterium tuberculosis. It is characterized by a longer time to culture conversion to negative and a risk of uncontrolled diabetes that requires frequent treatment adjustment and insulin use.

Population diversity of Staphylococcus intermedius isolates from various host species: typing by 16S-23S intergenic ribosomal DNA spacer polymorphism analysis.

Twelve 16S-23S ribosomal DNA intergenic spacer (ITS-PCR) types were identified among 57 Staphylococcus intermedius isolates from humans and other animals. Six ITS-PCR types were host specific, and most human and canine strains belonged to the same types (A and J). Pigeon, horse, and mink strains appeared more heterogeneous.