Primary and acquired resistance of Mycobacterium tuberculosis in Western Mexico

Prevalence of multidrug-resistant tuberculosis in Latin America and the Caribbean: a systematic review and meta-analysis

OBJECTIVES

To evaluate the prevalence of multidrug-resistant tuberculosis (MDR-TB) in individuals living in Latin America and the Caribbean (LAC).

METHODS

We searched the MEDLINE, Embase and Literatura Latino Americana e do Caribe em Ciências da Saúde (Lilacs) databases until 08 August 2019 for all studies on the subject, without time or language restrictions. Original studies reporting the prevalence of infection with Mycobacterium tuberculosis resistant to isoniazid and rifampicin simultaneously (MDR) in LAC, the prevalence of resistance in cases with no previous treatment (new cases) and the prevalence of resistance in previously treated cases were selected. Considering the expected heterogeneity between studies, all analyses were performed using the random effects model, and heterogeneity was assessed using the I² statistic.

RESULTS

We included 91 studies from 16 countries. The estimated overall prevalence was 13.0% (95% CI 12.0-14.0%), and the heterogeneity between studies was substantial (I²  = 96.1%). In the subgroup analyses, it was observed that the prevalence of MDR-TB among new cases was 7.0% (95% CI 6.0-7.0%) and in previously treated cases was 26.0% (95% CI 24.0-28.0%).

CONCLUSIONS

This review highlights multidrug resistance to antituberculosis drugs in LAC, indicating that prevention strategies have not been effective. Government institutions should invest heavily in strategies for early diagnosis and the rapid availability of effective treatments and prioritise adequate protection for health professionals. In addition, screening programmes should be adopted to prevent secondary cases.

Large Retropharyngeal Abscesses in an Immunocompetent Adult Patient with Disseminated Tuberculosis

BACKGROUND The retropharyngeal abscess is a rare presentation of head and neck tuberculosis. The pathogenesis of the abscess formation in the retropharyngeal space in the adult is controversial. CASE REPORT We report a case of large retropharyngeal abscesses in a 46-year-old man with disseminated tuberculosis. The patient had severe progressive dysphagia, weight loss, and a slowly enlarging bilateral cervical mass during a period of three months. His posterior pharynx wall was bulging and red, and both tonsils were enlarged and congested. The neck had an abscess of 5 cm in diameter that was firm, tender, and warm along the left sternocleidomastoid muscle. Palpable bilateral lymphadenitis was detected in the submandibular, cervical, axillary, and inguinal regions. A computed tomographic (CT) scan of the neck revealed large bilobulated retropharyngeal abscesses. A liver ultrasound showed multiple hypoechoic lesions. A Ziehl-Neelsen smear for acid-fast bacilli was positive from different abscess samples, and mycobacterial cultures subsequently yielded Mycobacterium tuberculosis. Antituberculous therapy was begun and the retropharyngeal abscesses were aspirated by external incision with complete drainage and relief of symptoms. CONCLUSIONS Large retropharyngeal abscess is a rare entity in which Mycobacterium tuberculosis etiology should be considered, especially in endemic countries, and the diagnosis may be difficult because symptoms and signs are influenced by abscess size and time of onset, or if the etiology is not suspected.

Characterization of phenotypic and genotypic drug resistance patterns of Mycobacterium tuberculosis isolates from a city in Mexico

INTRODUCTION

The emergence of multidrug-resistant (MDR) Mycobacterium tuberculosis strains has become a worldwide health care problem, making treatment of tuberculosis difficult. The aim of this study was to determine phenotypic resistance and gene mutations associated with MDR of clinical isolates of Mycobacterium tuberculosis from Guadalajara, Mexico.

METHODS

One hundred and five isolates were subjected to drug susceptibility testing to first line drugs using the proportion and Mycobacteria Growth Indicator Tube (MGIT) methods. Genes associated with isoniazid (inhA, katG, ahpC) and rifampicin (rpoB) resistance were analyzed by either pyrosequencing or PCR-RFLP.

RESULTS

Resistance to any drug was detected in 48.6% of isolates, of which 40% were isoniazid-resistant, 20% were rifampicin-resistant and 19% were MDR. Drug-resistant isolates had the following frequency of mutations in rpoB (48%), katG (14%), inhA (26%), ahpC (26%). Susceptible isolates also had a mutation in ahpC (29%).

CONCLUSIONS

This is the first analysis of mutations associated with MDR of M. tuberculosis in Guadalajara. Commonly reported mutations worldwide were found in rpoB, katG and inhA genes. Substitution C to T in position -15 of the ahpC gene may possibly be a polymorphism.

Incidence of multidrug-resistant tuberculosis disease in children: systematic review and global estimates

BACKGROUND

Multidrug-resistant tuberculosis threatens to reverse recent reductions in global tuberculosis incidence. Although children younger than 15 years constitute more than 25% of the worldwide population, the global incidence of multidrug-resistant tuberculosis disease in children has never been quantified. We aimed to estimate the regional and global annual incidence of multidrug-resistant tuberculosis in children.

METHODS

We developed two models: one to estimate the setting-specific risk of multidrug-resistant tuberculosis among child cases of tuberculosis, and a second to estimate the setting-specific incidence of tuberculosis disease in children. The model for risk of multidrug-resistant tuberculosis among children with tuberculosis needed a systematic literature review. We multiplied the setting-specific estimates of multidrug-resistant tuberculosis risk and tuberculosis incidence to estimate regional and global incidence of multidrug-resistant tuberculosis disease in children in 2010.

FINDINGS

We identified 3403 papers, of which 97 studies met inclusion criteria for the systematic review of risk of multidrug-resistant tuberculosis. 31 studies reported the risk of multidrug-resistant tuberculosis in both children and treatment-naive adults with tuberculosis and were used for evaluation of the linear association between multidrug-resistant disease risk in these two patient groups. We identified that the setting-specific risk of multidrug-resistant tuberculosis was nearly identical in children and treatment-naive adults with tuberculosis, consistent with the assertion that multidrug-resistant disease in both groups reflects the local risk of transmitted multidrug-resistant tuberculosis. After application of these calculated risks, we estimated that around 999,792 (95% CI 937,877-1,055,414) children developed tuberculosis disease in 2010, of whom 31,948 (25,594-38,663) had multidrug-resistant disease.

INTERPRETATION

Our estimates underscore that many cases of tuberculosis and multidrug-resistant tuberculosis disease are not being detected in children. Future estimates can be refined as more and better tuberculosis data and new diagnostic instruments become available.

FUNDING

US National Institutes of Health, the Helmut Wolfgang Schumann Fellowship in Preventive Medicine at Harvard Medical School, the Norman E Zinberg Fellowship at Harvard Medical School, and the Doris and Howard Hiatt Residency in Global Health Equity and Internal Medicine at the Brigham and Women's Hospital.

Isoniazid-resistant tuberculosis in children: a systematic review

BACKGROUND

Isoniazid resistance is an obstacle to the treatment of tuberculosis disease and latent tuberculosis infection in children. We aim to summarize the literature describing the risk of isoniazid-resistant tuberculosis among children with tuberculosis disease.

METHODS

We did a systematic review of published reports of children with tuberculosis disease who had isolates tested for susceptibility to isoniazid. We searched PubMed, Embase and LILACS online databases up to January 12, 2012.

RESULTS

Our search identified 3403 citations, of which 95 studies met inclusion criteria. These studies evaluated 8351 children with tuberculosis disease for resistance to isoniazid. The median proportion of children found to have isoniazid-resistant strains was 8%; the distribution was right-skewed (25th percentile: 0% and 75th percentile: 18%).

CONCLUSIONS

High proportions of isoniazid resistance among pediatric tuberculosis patients have been reported in many settings suggesting that diagnostics detecting only rifampin resistance are insufficient to guide appropriate treatment in this population. Many children are likely receiving substandard tuberculosis treatment with empirical isoniazid-based regimens, and treating latent tuberculosis infection with isoniazid may not be effective in large numbers of children. Work is needed urgently to identify effective regimens for the treatment of children sick with or exposed to isoniazid-resistant tuberculosis and to better understand the scope of this problem.

Antituberculosis drug resistance patterns in two regions of Turkey: a retrospective analysis

BACKGROUND

The emergence of Mycobacterium tuberculosis strains resistant to antituberculosis agents has recently received increased attention owing largely to the dramatic outbreaks of multi drug resistance tuberculosis (MDR-TB).

METHODS

Patients residing in Zonguldak and Kayseri provinces of Turkey with, pulmonary tuberculosis diagnosed between 1972 and 1999 were retrospectively identified. Drug susceptibility tests had been performed for isoniazid (INH), rifampin (RIF), streptomycin (SM), ethambutol (EMB) and thiacetasone (TH) after isolation by using the resistance proportion method.

RESULTS

Total 3718 patients were retrospectively studied. In 1972-1981, resistance rates for to SM and INH were found to be 14.8% and 9.8% respectively (n: 2172). In 1982-1991 period, resistance rates for INH, SM, RIF, EMB and TH were 14.2%, 14.4%, 10.5%, 2.7% and 2.9% (n: 683), while in 1992-1999 period 14.4%, 21.1%, 10.6%, 2.4% and 3.7% respectively (n: 863). Resistance rates were highest for SM and INH in three periods. MDR-TB patients constituted 7.3% and 6.6% of 1982-1991 and 1992-1999 periods (p > 0.05).

CONCLUSION

This study demonstrates the importance of resistance rates for TB. Continued surveillance and immediate therapeutic decisions should be undertaken in order to prevent the dissemination of such resistant strains.