Distribution of methicillin-resistant Staphylococcus aureus in a low-prevalence area.

Investigating circulating methicillin-resistant Staphylococcus aureus (MRSA) strains and identifying their accumulations in society are important in the search for strategies for eradicating the pathogen. The aim of this study was to describe the distribution of MRSA in a low-prevalence area where MRSA could be establishing endemicity. MRSA isolates from 802 patients (803 isolates) were included and placed into a timeline (1991-2006) under different categories: hospital (n=270), long-term care facility (LTCF) (n=175) and general practitioner (GP) (n=358). MRSA isolates had been characterized using multilocus sequence-typing, staphylococcal cassette chromosome mec-typing and detection of Panton-Valentine leukocidin-encoding genes (lukS/F-PVL), and were placed in exotoxin-encoding gene clusters. The GP category increased mainly in a cluster with few exotoxin-encoding genes (r=0.760), the LTCF (r=0.804) and the hospital category (r=0.876) mainly in clusters with more exotoxin-encoding genes. ST8-IV, lukS/F-PVL present, increased in the community (1-41 isolates) in the time period 2002-2006, later in the hospital (1-8 isolates, 2004-2006), and finally reached the LTCF (1 isolate, 2006). ST8-IV, lukS/F-PVL absent, could have attained endemicity in LTCFs, where 51 isolates were isolated in 2006. ST125-IV, lukS/F-PVL absent, showing epidemic qualities abroad, caused outbreaks at five LTCFs.

Use of interferon gamma-based assay to diagnose tuberculosis infection in health care workers after short term exposure.

BACKGROUND: We intended to assess the risk for health care workers (HCWs) of acquiring M. tuberculosis infection after exposure to patients with sputum-smear positive pulmonary tuberculosis at three University Hospitals (Ullevål, Akershus, and Haukeland) in Norway. METHODS: We tested 155 exposed health care workers and 48 healthy controls both with a tuberculin skin test (Mantoux) and the T-SPOT.TB test, a recently developed interferon-gamma release assays based on the M. tuberculosis-specific ESAT-6 and CFP10 antigens, to investigate if this test might improve infection control measures. RESULTS: Among the 155 exposed HCWs tested in this study, 27 individuals were defined as newly infected cases by TST after recent exposure, while only 3 of these had a positive T-SPOT.TB test. The number of T-SPOT.TB positives represents 11% of the individuals defined as recently infected by TST after exposure (3/27) and 2% of the total number of exposed people tested (3/155). In addition, 15 individuals had been previously defined as infected by TST before exposure of whom 2 subjects were T-SPOT.TB positive. All individuals detected as T-SPOT.TB positive belonged to the TST positive group (> 15 mm), and the percentage concordance between T-SPOT.TB and TST, including both previously and newly infected subjects, was 12% (5/42). The 48 control participants used in the study were all T-SPOT.TB negative, but 3 of these subjects were TST positive. CONCLUSION: Our data indicate that the frequency of latent TB in the total cohort of HCWs is 3%, whereas the rate of transmission of TB to exposed individuals is approximately 2% and occurs through exposure periods of short duration. Thus, the risk of TB transmission to HCWs following TB exposure in a hospital setting in Norway is low, and improved screening approaches will benefit from the application of specific interferon-gamma release assays.

A systematic review of delay in the diagnosis and treatment of tuberculosis.

BACKGROUND: Early diagnosis and immediate initiation of treatment are essential for an effective tuberculosis (TB) control program. Delay in diagnosis is significant to both disease prognosis at the individual level and transmission within the community. Most transmissions occur between the onset of cough and initiation of treatment. METHODS: A systematic review of 58 studies addressing delay in diagnosis and treatment of TB was performed. We found different definitions of, for example, debut of symptoms, first appropriate health care provider, time to diagnosis, and start of treatment. Rather than excluding studies that failed to meet strict scientific criteria (like in a meta-analysis), we tried to extract the "solid findings" from all of them to arrive on a more global understanding of diagnostic delay in TB. RESULTS: The main factors associated with diagnostic delay included human immunodeficiency virus; coexistence of chronic cough and/or other lung diseases; negative sputum smear; extrapulmonary TB; rural residence; low access (geographical or sociopsychological barriers); initial visitation of a government low-level healthcare facility, private practitioner, or traditional healer; old age; poverty; female sex; alcoholism and substance abuse; history of immigration; low educational level; low awareness of TB; incomprehensive beliefs; self-treatment; and stigma. CONCLUSION: The core problem in delay of diagnosis and treatment seemed to be a vicious cycle of repeated visits at the same healthcare level, resulting in nonspecific antibiotic treatment and failure to access specialized TB services. Once generation of a specific diagnosis was in reach, TB treatment was initiated within a reasonable period of time.

Drug resistance of Mycobacterium tuberculosis in the Sunamganj District of Bangladesh.

Spread of drug-resistant tuberculosis (TB) threatens TB-control programmes, and all countries need to monitor the patterns and trends of anti-TB drug resistance. Such data assess the quality of control programmes and help forecast future trends of drug resistance. It will also help to establish guidelines for TB therapy. The aim of the current study was to describe the rate of drug-resistant Mycobacterium tuberculosis in the Sunamganj District of Bangladesh. Bacterial isolates were collected from sputum smear positive (ss+) patients who attended the National TB Programme from November 2003 to December 2004. A total of 95 isolates was tested for susceptibility to streptomycin (SM), isoniazid (INH), rifampicin (RMP) and ethambutol (EMB) at the National Reference Laboratory for Mycobacteria at the Norwegian Institute of Public Health (NIPH), Oslo. The total resistance among new cases to any drug was 31%. For SM it was 18%, INH 23%, RMP 2%, EMB 10% and 2% were multidrug-resistant (MDR). The National Tuberculosis Programme (NTP) in Sunamganj is still effective, although the high resistance to INH is alarming. An increased risk of treatment failure has been demonstrated in areas with high levels of INH resistance, and a high proportion of INH resistant cases may develop resistance to RMP during treatment.

Heterogeneity of Mycobacterium tuberculosis isolates in Sunamganj District, Bangladesh.

A total of 111 Mycobacterium tuberculosis isolates from new pulmonary tuberculosis patients, living in the rural Sunamganj district in northern Bangladesh were characterized with IS6110 restriction fragment length polymorphism analyses and spoligotyping. Only 3 of the isolates belonged to the W-Beijing genotype of M. tuberculosis. A high degree of diversity indicated that the spread of M. tuberculosis, in this rural area, was not caused by closely related genotypes. The tuberculosis cases in the current study were less likely to represent recent transmission than what is commonly observed in urban parts of south-east Asia. It was indicated that the tuberculosis cases of this isolated area, of a high-incidence country, represented those of an established epidemic, not yet influenced by recently disseminated strains.