In this outbreak, Y pseudotuberculosis was for the first time detected in both patient and food samples. ReA was more common than earlier reported in the outbreaks associated with this pathogen; the reason may be that the previous outbreaks have occurred among children. HLA-B27 frequency was higher than usually reported in single-source outbreaks of ReA.

Streptococcus pneumoniae is a well-known cause of community-acquired bacterial pneumonia. The purpose of this study was to assess the cause and extent of the outbreak of pneumonia which occurred among military recruits following a 1-week hard encampment in Finland. We also assessed the carriage rate and molecular characteristics of the S. pneumoniae isolates. All pneumococcal isolates were studied for antibiotic susceptibility, serotyped, genotyped by multilocus sequence typing (MLST), and the presence of pneumococcal rlrA pilus islet was detected. The genotype results defined by MLST corresponded with the serotype results. S. pneumoniae serotype 7F, ST2331, seemed to be associated with an outbreak of pneumonia and nasopharyngeal carriage among 43 military recruits. Of the 43 military recruits, five (12%) were hospitalized with pneumonia and two (40%) of them were positive for S. pneumoniae serotype 7F, ST2331 by blood culture. Eighteen (42%) of the 43 men were found to be positive for S. pneumoniae by nasopharyngeal culture, and nine (50%) of them carried pneumococcal serotype 7F, ST2331. The outbreak strain covered 55% of all the pneumococcal findings. Outbreaks of invasive pneumococcal disease seem to occur in a crowded environment such as a military training facility even among previously healthy young men.

Patients with mixed connective tissue disease (MCTD, n=32)

Twenty-eight patients with rheumatoid pleural effusion were investigated to examine the frequency of HLA antigens as compared with 56 rheumatoid arthritis (RA) patients without this intrathoracic manifestation of RA and with 283 healthy controls. HLA-B8 was strongly associated with the presence of pleural effusion (PE) in RA patients. A high prevalence (71%) of B8/Dw3 was found among male RA patients of the PE group in whom the joint disease had begun at an age over 50 years and who also had besides pleuritis other intrathoracic manifestations of RA associated with high rheumatoid factor titres and low complement (C4) levels in sera. Actually, the HLA-B8 association was not seen in the rest of the PE group. The finding may be related to the heterogeneity of RA, a male subgroup of the disease being characterized by multiple intrathoracic manifestations and genetically associated with the large group of autoimmune disorders, such as SLE, characterized by high prevalences of HLA-B8 and D(R)3.