Outbreak of multidrug-resistant tuberculosis in two secondary schools

OBJECTIVES

To describe an outbreak of multidrug-resistant tuberculosis (MDR-TB) in two schools

METHODS

This was a prospective, observational study of an outbreak of MDR-TB in 2 schools located in the towns of Onda and Nules, in the Spanish province of Castellon, from the moment of detection in November 2008 until November 2014, including patient follow-up and contact tracing.

RESULTS

Five cases of MDR-TB were diagnosed. Overall attack rate was 0.9%, and among the contacts traced, 66 had latent tuberculous infection, with an infection rate of 14.4%. Molecular characterization of the 5M. tuberculosis isolates was performed by restriction fragment length polymorphism (RFLP) analysis of the IS6110 sequence. In all 5 patients, cultures were negative at 4-month follow-up, showing the efficacy of the treatment given. No recurrence has been reported to date.

CONCLUSIONS

In the context of globalization and the increased prevalence of MDR-TB, outbreaks such as the one presented here are only to be expected. Contact tracing, strict follow-up of confirmed cases, the availability of fast diagnostic techniques to avoid treatment delay, and chemoprophylaxis, together with the molecular characterization of strains, are still essential.

[Influence of immigration on tuberculosis transmission patterns in Castellón, Spain (2004-2007)]

BACKGROUND

This study aimed to identify tuberculosis transmission patterns in Castellón in a period of major demographic changes.

METHODS

A prospective study of patients with positive culture in the province of Castellon over a 4-year period (2004-2007) was carried out. Cases were described by year and nationality and were compared with those reported to the Department of Public Health. We studied the population with available molecular patterns, identified through restriction fragment length polymorphism (RFLP) and analyzed the variables from patient clusters, based on data collected in surveys of the Department of Health and the Laboratory Management Program.

RESULTS

According to data from the Department of Public Health, the overall rate of tuberculosis per 100,000 inhabitants in the province of Castellón was 15.7 in 2004, 19.9 in 2005, 18.2 in 2006 and 17.5 in 2007. In our laboratory, strains were identified from 301 patients, representing 77% (301/390) of reported cases and 94% (301/321) of reported cases with a positive culture. The percentage of tuberculosis among foreigners increased with age, exceeding 50% in 2007. Molecular studies were available in 95% of patients (286); 58% were Spanish and 42% were foreigners, of whom 54% were Romanians. The cluster percentage was 40%, with 30% of mixed clusters. According to conventional contact studies, 85% of patients in clusters had been considered isolated cases.

CONCLUSIONS

The increased rate of tuberculosis in Castellón was mainly due to the increasing number of cases among foreigners, mostly Romanians. The availability of molecular studies in all patients with a positive culture allowed us to analyze how and where tuberculosis is transmitted in our province. Forty percent of the patients were grouped into clusters; of these, mixed clusters accounted for one third, indicating the high integration of immigrants in our area.

[The importance of genotyping of strains for the evaluation and interpretation of 5 school-based epidemic outbreaks of tuberculosis]

OBJECTIVE

The aim of this study was to describe 5 microepidemics of tuberculosis occurring in schools, establish the risk factors associated with the outbreaks, assess how well a concentric circles strategy for contact tracing predicts infection, and assess the usefulness of genotyping strains in the analysis of the outbreaks.

MATERIAL AND METHODS

The study assessed 5 epidemic outbreaks of tuberculosis using a standard contact tracing procedure. The outbreaks occurred in 2 day nurseries and 2 high schools between 1998 and 2005. Contacts were stratified using a concentric circle system based on level of exposure. DNA fingerprints of the available strains were determined based on the restriction fragment length polymorphism (RFLP) IS6110 and compared with the contact study to interpret the transmission of the infection.

RESULTS

We analyzed 5 outbreaks. Eighty-five contacts were analyzed in the first outbreak, 519 in the second, 116 in the third, 655 in the fourth, and 102 in the fifth. The rate of infection was 31%, 29%, 66%, 37.6%, and 32%, respectively. Secondary cases of active disease were detected: 9 in the first outbreak, 16 in the second, 5 in the third, 6 in the fourth, and 13 in the fifth. RFLP analysis revealed that a single strain was involved in 3 of the outbreaks, and in a fourth, at least 2 strains were involved. In outbreaks 2, 3, and 5, there was a significant association between the degree of contact and the probability of infection (P< .05). In all of the outbreaks, the relative risk of developing the disease was associated with the level of exposure.

CONCLUSIONS

Analysis of contacts based on concentric circles of risk predicts the likelihood of infection. RFLP facilitates analysis of complex transmission routes that are not detected using traditional methods of contact screening.

[Innovative strategies to diagnose and monitor tuberculosis patients]

Mycobacterium tuberculosis is the single most deadly microorganism worldwide. A third of the world population is thought to have latent tuberculosis and approximately 2 million people die of the disease each year. Short and closely supervised treatment regimens are needed, but it is also essential to develop new strategies to ensure prompt diagnosis of the disease. In particular, cheap methods are needed to tackle tuberculosis from a population perspective. The present article reviews the advances in immunology and molecular strategies for epidemiological diagnosis and monitoring of tuberculosis patients.