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In recent years, the incidence of invasive meningococcal disease (IMD) caused by serogroup W (SG-W) has been rising, in particular SG-W within clonal complex 11 (cc11), which has caused epidemics and is believed to cause severe and atypical IMD. This is a case report of spon-taneous bacterial peritonitis and bacteraemia caused by meningococci SG-W cc11 in a 60-year-old female with systemic lupus erythematosus in prolonged remission as her only risk factor. Antibiotic therapy was initiated at admission, and peritoneal lavage was performed. The patient recovered successfully without sequelae.

The epidemiological pattern of Mycoplasma pneumoniae infections in Denmark over the 50-year period 1946-1995 is described. The study is based on blood specimens received at the central laboratory at Statens Serum Institut for titration of cold agglutinins (CA), initially for the diagnosis of CA positive primary atypical pneumonia, and during the 1960s of M. pneumoniae infection; in addition, specimens from the last 38 years were tested for antibodies specific to M. pneumoniae. By retrospective analysis of the test results compiled over the years it was found that intervals of regular periodicity have been interrupted by an era of changes in the pattern. Attention is paid to the significance of CA for this study, and the possible background of the epidemiological pattern is described.

The study was based on a computerized card index of 9161 patients who had at least one positive blood specimen in the Mycoplasma pneumoniae complement fixation test. A total of 12,562 specimens from these patients had been sent to Statens Seruminstitut from hospitals and general practitioners during a 10.5-year period. The period encompassed a previously described endemic period in a 30-year study of the epidemiological pattern of M. pneumoniae infection in Denmark. The serological data presented support the hypothesis advanced here that a more than sixfold increase of children in day care might have contributed to a change in the epidemiological pattern. The correlation between age and level of specific antibodies, as well as persistence of seropositivity, were also investigated.

During the period 1 July 1978 to 1 January 1982, sera from 728 patients suspected of suffering from Legionella infection were tested for Legionella antibodies by an indirect fluorescent antibody test. The antigens used were prepared from heat-killed strains of L.pneumophila serogroups 1-4. In 1981 we further incorporated antigens from serogroups 5 and 6 of L.pneumophila together with L.micdadei, L.bozemanii, L.dumoffii and L.gormanii. According to the criteria put forward by CDC, Atlanta, USA Legionella infection was confirmed in 78 patients with pneumonia. Sera from 35 showed at least a four-fold rise in titre to greater than or equal to 128, while 43 had single or static titres of greater than or equal to 256. There were 59 men and 19 women (3.1:1) with a median age of 51 and 49, respectively. More than half the patients showed maximum titres of antibodies to L.pneumophila serogroup 1. In an additional patient, who was not tested serologically, the diagnosis was made post mortem at CDC by demonstration of Legionella in lung tissue. There were 11 fatal cases among the 79 patients (13.9%). Thirty-two had contracted the disease on a journey abroad. All cases except the seven first cases among tourists from Garda, Italy, were sporadic. The number of cases diagnosed has increased heavily while the proportion of imported cases has decreased.

The study is a retrospective and prospective serological investigation of the incidence of Mycoplasma (M.) pneumoniae infection in Denmark during a 17-year period. By least square multiple regression analysis it was shown that four major outbreaks or epidemics had occurred which culminated at regular intervals of four and a half years. The study was based on cold agglutinin (CA) positive sera tested for antibodies to M. pneumoniae by an indirect immunofluorescence (IF) test, an indirect haemagglutination (IHA) test or a complement fixation (CF) test. By the criteria chosen for a positive test, the CF test was found to detect more cases than the IF or IHA tests. A shift during the study from the latter two tests to the CF test influenced the incidence, but not the periodicity of epidemics. The consequence of including only CA positive sera in the study was investigated.

The variations in the incidence of Mycoplasma pneumoniae infections in Denmark over a period of 17 years could be demonstrated in the central serological laboratory which serves the whole of the population. This observation was made possible for the first and major part of this study by testing cold agglutinin (CA) positive sera, which had been kept frozen sine 1958, for antibodies to M.pneumoniae. The second part of the study is based upon results from routine tests for CA and M.pneumoniae antibodies on all samples which we receive. A statistical analysis of the total material indicates that four epidemics of M.pneumoniae antibodies on all samples which we receive. A statistical analysis of the total material indicates that four epidemics of M.pneumoniae infection had taken place from January 1958 to December 1974 and that these epidemics occurred at regular four and a half year intervals. By a follow-up of the study a fifth epidemic was demonstrated during the first eight months of 1975 which broke the regular periodicity by appearing two years earlier than expected. The consequences of including only CA positive sera in this study was investigated. Antibodies to M.pneumoniae were measured by either an indirect immunofluorescence test, an indirect haemagglutination test or a complement fixation test. The observed difference in sensitivity of these tests is discussed in relationship to a possible influence on the overall incidence.

A microagglutination (MA) test for antibodies to 10 different Legionella antigens was evaluated by comparison with an indirect fluorescent antibody (IFA) test. Sera from 227 patients were investigated. There was good agreement between the two tests, especially when testing sera from patients with a rise in titre. The MA is promising as an easy, quick, cheap and reproducible test for antibodies to Legionella.

During a 14-month study period, 92 patients admitted to the University Clinic for Infectious Diseases with pneumonia were investigated to determine the prevalence and severity of Legionnaires' disease (LD). The diagnosis of LD was based on positive serology. Antibodies to 10 different legionella antigens--Legionella pneumophila serogroups 1-6, Fluoribacter (Legionella) bozemanae, F. dumoffii, F. gormanii, and Tatlockia (Legionella) micdadei--were measured by the microagglutination (MA) and indirect fluorescent antibody (IFA) techniques. LD was diagnosed in 22 patients showing a 4-fold or greater rise of MA titers. 10 patients showed a 4-fold or greater rise of IFA titer, 2 had standing high titer. One patient died. Legionella infection was the second most common cause of pneumonia. However, in half of the cases legionella infection occurred concomitantly with Streptococcus pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae, Chlamydia psittaci, or viral infections. All 22 LD cases were sporadic. LD had been contracted abroad by 6 patients. Two of the legionella pneumonias were hospital-acquired. Half of the LD patients were older than 60 years. The majority of cases occurred during the winter months. Neither clinical chemistry parameters nor clinical features could distinguish LD from other types of pneumonia.

A seroepidemiological survey has shown a remarkable shift in the previously reported regular cyclic pattern of Mycoplasma pneumoniae epidemics which culminated every 4.5 years during the period 1958-74. The last of four regular epidemics occurred in 1972. It was followed by 'premature' epidemics in 1975 and 1977/8 which inaugurated a change from an epidemic to an endemic pattern of the infection in Denmark. Over the following 9 years (1978-86) there has been an irregular but significant decrease in the annual number of seropositive samples with the usual high incidence during winter seasons. This endemic period terminated in the fourth trimester of 1987 with the development of a new epidemic. The hypothesis is advanced that a sixfold increase of children in day care may have influenced the change from an epidemic to an endemic situation which after 9 years led to a new epidemic of M. pneumoniae infection.

An indirect immunofluorescence (IF) test for Legionella antibodies has been used since 1978 at Statens Seruminstitut, Copenhagen. An increasing annual number of blood specimens from all parts of the country has been tested by IF and the number of Legionella antigens in the test was increased from 4 over 10 to 13, resulting in an ever growing number of seropositive patients over the years. We investigated the occurrence of serologically diagnosed Legionella infections from November 1982 through February 1985, a period of 28 months during which the same 13 Legionella antigens were applied in the IF test. We used CDC's criteria for the serological diagnosis of a current Legionella infection: a greater than or equal to 4-fold rise in antibody titre to greater than or equal to 128 in the IF test. In a test of more than 5,000 blood specimens from 3,374 patients, 69 were found to have diagnostic titre rises. When analysed according to serological reactions with three groups of antigens, seroconversion to a L. pneumophila antigen was found to be more frequent in patients 30-59 years old than seroconversion to a non-L. pneumophila Legionella antigen, while in the age group 60-69 this relation was reversed. Thirteen of the 69 patients had acquired their infection abroad. Twelve of these were below the age of 60, and they had all seroconverted to a L. pneumophila antigen. Clinical data were in accordance with the assumption that Legionella may have been the aetiological agent of the disease in our patients selected by serological criteria.(ABSTRACT TRUNCATED AT 250 WORDS)