Multiple strains of Mycobacterium avium subspecies hominissuis infections associated with aborted fetuses and wasting in pigs.

A herd of pigs being reared for breeding and fattening, in which there had been incidences of abortion and wasting, reduced growth rates and an increase in mortality for the past year, were tested for Mycobacterium infection by pathological examinations, skin test, serology and Mycobacterium culture. In one placenta, and also in the lung tissues of fetuses, Ziehl-Neelsen staining revealed acid-fast bacilli in combination with infiltrations of neutrophils, macrophages and multinucleated giant cells. Acid-fast bacilli were also found in the mesenteric lymph nodes, liver and/or spleen and jejunum of pigs with wasting and in slaughtered animals. The specimen cultures were identified as Mycobacterium avium subspecies hominissuis using IS1245-specific PCR and IS1245 restriction fragment length polymorphism (RFLP). IS1245 RFLP revealed that the herd was infected with multiple M avium subspecies hominissuis strains belonging to at least two different clades. It is suggested that this infection may have played a more important role in the economic losses of the pig farm than had been assumed previously.

Lymphadenitis in children is caused by Mycobacterium avium hominissuis and not related to 'bird tuberculosis'.

Mycobacterium avium is the most commonly encountered mycobacterium species among non-Mycobacterium tuberculosis complex (nontuberculous mycobacteria) isolates worldwide and frequently causes lymphadenitis in children. During a multi-centre study in The Netherlands that was performed to determine the optimal treatment for mycobacterial lymphadenitis, concern was expressed in the media about the possible role of birds as sources of these M. avium infections, referred to as 'bird tuberculosis.' To examine the involvement of birds in mycobacterial lymphadenitis, 34 M. avium isolates from lymphadenitis cases were subjected to IS1245 restriction fragment length polymorphism (RFLP) typing. This genotyping method enables the distinction of the subspecies M. avium subsp. hominissuis and the 'bird-type' M. avium spp. avium. Highly variable RFLP patterns were found among the lymphadenitis M. avium isolates, and all belonged to the M. avium hominissuis subspecies. A relation to pet birds in the etiology of mycobacterial lymphadenitis could not be established, and the source of the infections may be environmental.

Completeness of notification of tuberculosis in The Netherlands: how reliable is record-linkage and capture-recapture analysis?

The aim of this study was to describe a systematic process of record-linkage, cross-validation, case-ascertainment and capture-recapture analysis to assess the quality of tuberculosis registers and to estimate the completeness of notification of incident tuberculosis cases in The Netherlands in 1998. After record-linkage and cross-validation 1499 tuberculosis patients were identified, of whom 1298 were notified, resulting in an observed under-notification of 13.4%. After adjustment for possible imperfect record-linkage and remaining false-positive hospital cases observed under-notification was 7.3%. Log-linear capture-recapture analysis initially estimated a total number of 2053 (95% CI 1871-2443) tuberculosis cases, resulting in an estimated under-notification of 36.8%. After adjustment for possible imperfect record-linkage and remaining false-positive hospital cases various capture-recapture models estimated under-notification at 13.6%. One of the reasons for the higher than expected estimated under-notification in a country with a well-organized system of tuberculosis control might be that some tuberculosis cases, e.g. extrapulmonary tuberculosis, are managed by clinicians less familiar with notification of infectious diseases. This study demonstrates the possible impact of violation of assumptions underlying capture-recapture analysis, especially the perfect record-linkage, perfect positive predictive value and absent three-way interaction assumptions.

Public health impact of isoniazid-resistant Mycobacterium tuberculosis strains with a mutation at amino-acid position 315 of katG: a decade of experience in The Netherlands.

A previous limited study demonstrated that Mycobacterium tuberculosis isolates with a mutation at amino-acid position 315 of katG (Delta315) exhibited high-level resistance to isoniazid and were more frequently resistant to streptomycin. In the present study, isoniazid-resistant M. tuberculosis isolates from 8,332 patients in The Netherlands (1993-2002) were screened for the Delta315 mutation. Isoniazid resistance was found in 592 (7%) isolates, of which 323 (55%) carried Delta315. IS6110 restriction fragment length polymorphism analysis showed that Delta315 isolates occurred in clusters, suggesting recent transmission, at the same frequency as isoniazid-susceptible isolates. In contrast, other isoniazid-resistant isolates clustered significantly less frequently. Delta315 isolates were high-level isoniazid-resistant, streptomycin-resistant and multidrug-resistant significantly more often, and may have a greater impact on public health, than other isoniazid-resistant isolates.