Nosocomial transmission of tuberculosis in two hospitals for mentally handicapped patients

Assessment of latent tuberculosis infection in psychiatric inpatients: A survey after tuberculosis outbreaks

BACKGROUND/PURPOSE

To investigate risk factors of latent tuberculosis infection (LTBI) among inpatients of chronic psychiatric wards with tuberculosis (TB) outbreaks.

METHODS

In April 2013, inpatients of four all-male wards with TB outbreaks were tested for LTBI using the QuantiFERON-TB Gold in Tube (QFT) method. Based on this investigation, a retrospective study was conducted to assess risk factors for LTBI. Inpatients exposed to cluster-A or cluster-B TB cases were defined as contacts of cluster-A or cluster-B, and others, as nonclustered contacts.

RESULTS

Among 355 inpatients with TB exposure, 134 (38%) were QFT-positive for LTBI. Univariate analysis showed that significant predictors for QFT-positivity were age, case-days of exposure to all TB cases (TB-all) and to sputum smear positive cases, number of source cases with cough, and exposure to cluster-A TB cases. Independent risk factors for LTBI were higher age [adjusted odds ratio (OR) 1.03, 95% confidence intervals (CI: 1.01-1.05)], TB-all exposure case-days ≥ 200 [adjusted OR 2.04 (1.06-3.92)] and exposure to cluster-A TB cases [adjusted OR 2.82 (1.30-6.12)] after adjustment for the sputum smear positivity, and cough variables of the source cases. The contacts of cluster-A had a greater risk of LTBI than did those of cluster-B, especially in the younger population (≤50 years) after adjustment [adjusted OR 2.64 (1.03-6.76)].

CONCLUSION

After TB outbreaks, more than one third of inpatients were QFT-positive for LTBI. Our findings suggest that, beside the infectiousness of source cases, intensity of exposure, and age of contacts, exposure to TB cases in potential genotyping clusters may be predictive for LTBI in this male psychiatric population.

Transmission of tuberculosis within family-households

OBJECTIVE

The introduction of molecular typing methods in the 1990s to study the epidemiology of tuberculosis (TB) has significantly improved the possibilities of quantifying transmission of Mycobacterium tuberculosis in different human settings. The purpose of this study was to investigate transmission of TB in 35 family-households in Poland.

METHODS

Two PCR-based genotyping methods: spoligotyping and mycobacterial interspersed repetitive unit-variable number of tandem repeats (MIRU-VNTR) typing were used.

RESULTS

Of 78 patients, 49 (63%), could be assigned to intra-household transmission on the basis of identical DNA fingerprints upon a combined typing approach. However, if a single spoligotype spacer or a single MIRU-VNTR locus variation was tolerated in the cluster definition, the intra-household transmission raised to 85% of all patients. For 12 patients in 6 households, the M. tuberculosis isolates were clearly distinct in either spoligotyping or VNTR typing or in both genotyping methods, suggesting that these patients were infected by the sources in the community.

CONCLUSIONS

This study is the first to provide the results of a molecular epidemiological investigation performed within family-households in Poland. It shows the household setting as an important reservoir of M. tuberculosis transmission, and thus argues in favor of routine and extensive screening of the family contacts of TB patients.

Mixed infection with Beijing and non-Beijing strains and drug resistance pattern of Mycobacterium tuberculosis

Mixed infection with Beijing and non-Beijing strains of Mycobacterium tuberculosis has been reported and has been suggested to mediate elevation of the reinfection rate in regions with a high incidence of tuberculosis (TB). To evaluate the prevalence of infection with both Beijing and non-Beijing strains of M. tuberculosis in eastern Taiwan, the region with the highest TB incidence in Taiwan, 185 active pulmonary TB patients were enrolled at Tzu Chi General Hospital from October 2007 to September 2008. A modified multiplex PCR method was developed to distinguish Beijing and non-Beijing strains directly using the sputum of patients. Of the 185 patients, 46.5% were infected with a Beijing strain, 42.2% were infected with a non-Beijing strain, and 11.3% were infected with both strain types. Notably, mixed infection with both strain types was not associated with TB treatment history or the high-incidence race group, aborigines. In addition, the incidence rate of mixed infection before treatment with anti-TB medication was as high as that in patients with a history of anti-TB treatment. Further analysis of antibiotic susceptibility revealed that Beijing strains alone had the highest multidrug resistance rate (17.5%), mixed infection had the highest rate of resistance to at least one drug (23.8%), and non-Beijing strains had the highest rate of sensitivity to all drugs (79.5%), implying that Beijing strains are predominant in the development of drug resistance in tuberculosis.

"Cough officer screening" improves detection of pulmonary tuberculosis in hospital in-patients

Background

Current tuberculosis (TB) reporting protocols are insufficient to achieve the goals established by the Stop TB partnership. Some countries have recommended implementation of active case finding program. We assessed the effect of Cough Officer Screening (an active screening system) on the rate of TB detection and health care system delays over the course of four years.

Methods

Patients who were hospitalized at the Changhua Christian Hospital (Changhua, Taiwan) were enrolled from September 2004 to July 2006 (Stage I) and August 2006 to August 2008 (Stage II). Stage II was implemented after a Plan-Do-Check-Act (PDCA) cycle analysis indicated that we should exclude ICU and paediatric patients.

Results

In Stage I, our COS system alerted physicians to 19,836 patients, and 7,998 were examined. 184 of these 7,998 patients (2.3%) had TB. Among these 184 patients, 142 (77.2%) were examined for TB before COS alarming and 42 were diagnosed after COS alarming. In Stage II, a total of 11,323 patients were alerted by the COS system. Among them, 6,221 patients were examined by physicians, and 125 of these patients (2.0%) had TB. Among these 125 patients, 113 (90.4%) were examined for TB before COS alarming and 12 were diagnosed after COS alarming. The median time from COS alarm to clinical action was significantly less (p = 0.041) for Stage I (1 day; range: 0-16 days) than for Stage II (2 days; range: 0-10 days).

Conclusion

Our COS system improves detection of TB by reducing the delay from infection to diagnosis. Modifications of scope may be needed to improve cost-effectiveness.