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M Leinonen

Publications and source records attributed to M Leinonen.

At least 163 records · Page 9Linked to original sources
PubMed1993

Pathogenetic mechanisms and epidemiology of Chlamydia pneumoniae.

The antibody prevalence data indicate that C. pneumoniae infections are common worldwide and more frequently occur in middle-aged and elderly males than in females. C. pneumoniae infections are first acquired in childhood in heavily populated areas, whereas in northern countries, first infections are generally at teenage and in Scandinavia, typically at the time of military service. All chlamydial species tend to cause chronic infections, with severe sequelae developing 10 to 50 years after the primary infections. If C. pneumoniae resides in alveolar macrophages or in vascular endothelial cells in chronic infections the bacteria and their structural components, such as lipopolysaccharides have an easy access to circulation. The continuous induction of cytokines by C. pneumoniae may lead to chronic inflammation of vascular endothelium.

Antibodies, Bacterial↗
PubMed1992

Epidemiology of invasive pneumococcal infections in children in Finland.

OBJECTIVE: To study the epidemiologic characteristics of invasive infections in children caused by Streptococcus pneumoniae to provide background data for vaccination programs. DESIGN: A nationwide laboratory-based prospective surveillance of all invasive pneumococcal infections in children during 1985 through 1989. SETTING: A network of all microbiologic laboratories and pediatric wards in Finland. PATIENTS: Children aged 0 to 15 years who were admitted to a hospital with S pneumoniae isolated from blood, cerebrospinal fluid, or deep aspirate sample. RESULTS: Four hundred fifty-two invasive pneumococcal infections were diagnosed in 1985 through 1989. The annual incidence rate was 8.9 per 100,000 children less than 16 years of age (24.2 per 100,000 among children less than 5 years of age and 45.3 per 100,000 among those less than 2 years of age). The most common clinical entities were bacteremia without focus (310 cases), pneumonia (66 cases), and meningitis (51 cases), with other focal infections seen in 25 cases. The pneumococcal groups/types 14, 6, 19, 7, 18, and 23 comprised 78% of all invasive infections. CONCLUSIONS: Streptococcus pneumoniae is a common cause of invasive infections in children in Finland. A pneumococcal conjugate vaccine containing the six most common groups/types could prevent up to 70% of invasive pneumococcal infections of children in Finland if fully protective in infancy.

Adolescent↗
PubMed1992

Chronic Chlamydia pneumoniae infection as a risk factor for coronary heart disease in the Helsinki Heart Study.

OBJECTIVE: To investigate in the prospective Helsinki Heart Study, whether chronic Chlamydia pneumoniae infection, indicated by elevated antibody titers against the pathogen, chlamydial lipopolysaccharide-containing immune complexes, or both, is a risk factor for coronary heart disease. DESIGN AND SETTING: The Helsinki Heart Study was a randomized, double-blind, 5-year clinical trial to test the efficacy of gemfibrozil in reducing the risk for coronary heart disease. Participants were randomized to receive either gemfibrozil (2046 patients) or placebo (2035 patients). Fatal and nonfatal myocardial infarction and sudden cardiac death were the main study end points. Serum samples were collected at 3-month intervals from all patients. PATIENTS: One hundred forty cardiac events occurred during the follow-up period. Serum samples from 103 case patients obtained 3 to 6 months before a cardiac end point were matched with those from controls for time point, locality, and treatment. Samples were tested for markers of chronic chlamydial infection. MEASUREMENTS: Immunoglobulin A (IgA) and G (IgG) antibodies to C. pneumoniae were measured using the microimmunofluorescence method. Lipopolysaccharide-containing immune complexes were measured using two antigen-specific enzyme immunoassays, the lipopolysaccharide-capture and immunoglobulin M (IgM)-capture methods. MAIN RESULTS: Using a conditional logistic regression model, odds ratios for the development of coronary heart disease were 2.7 (95% CI, 1.1 to 6.5) for elevated IgA titers, 2.1 (CI, 1.1 to 3.9) for the presence of immune complexes, and 2.9 (CI, 1.5 to 5.4) for the presence of both factors. If we adjusted for other coronary heart disease risk factors such as age, hypertension, and smoking, the corresponding values would be 2.3 (CI, 0.9 to 6.2), 1.8 (CI, 0.9 to 3.6), and 2.6 (CI, 1.3 to 5.2), respectively. CONCLUSION: The results suggest that chronic C. pneumoniae infection may be a significant risk factor for the development of coronary heart disease.

Adult↗
PubMed1992

Pneumonia in childhood: etiology and response to antimicrobial therapy.

A prospective eight-month study was carried out in 50 children admitted to hospital for radiologically confirmed community-acquired pneumonia. A potential causative agent of infection was identified in 44 (88%) cases. Using virus isolation, virus antigen detection and enzyme immunoassay serology, respiratory virus infection was diagnosed in 30 (60%) patients. Antibody assays for seven bacteria and antigen detection from serum and urine for Streptococcus pneumoniae produced evidence of bacterial infection in 31 (62%) cases. Streptococcus pneumoniae (38%), respiratory syncytial virus (30%) and Mycoplasma pneumoniae (20%) were the most common causative agents. A mixed infection was diagnosed in 25 (50%) episodes. Nine patients failed to respond to antibiotics within 24 h after onset of treatment. Three of them had a pure viral infection, three a mixed viral-bacterial infection, two a Mycoplasma pneumoniae infection mixed with other bacteria and one a pure Mycoplasma pneumoniae infection. All three Mycoplasma pneumoniae infections were initially treated with penicillin.

Adolescent↗
PubMed1992

Etiology of acute lower respiratory tract infections in children in a rural community in The Gambia.

Approximately 500 children younger than 5 years old resident in 7 villages in a rural area of The Gambia were monitored closely for 1 year for episodes of acute lower respiratory tract infection (ALRI). Each episode was investigated with antigen detection techniques and antibody assays as well as culture for bacteria and viruses. A pathogen was identified in 76 (34.2%) of 222 cases with clinical signs of ALRI and in 34 (42%) of the 81 cases who, in addition, had radiologic evidence of ALRI. Evidence of infection with a bacterial pathogen, most commonly Streptococcus pneumoniae or Haemophilus influenzae, was obtained in 32 (14.4%) cases with clinical signs of ALRI (23.5% of those with radiologically proved pneumonia). Viral agents were cultured from 42 (19%) of 221 cases but also from 14 (14.6%) of 96 controls some of whom had minor symptoms of upper respiratory tract infection. In the absence of an outbreak of respiratory syncytial virus the viral agents recovered most often were influenza A and adenoviruses.

Bacterial Infections↗
PubMed1992

Role of non-capsulated Haemophilus influenzae as a respiratory pathogen in children.

During a 12-month surveillance period from 1981-1982, non-capsulated Haemophilus influenzae was detected in nasopharyngeal aspirates from 64 (14%) of the 449 children hospitalized for middle or lower respiratory infection. An antibody response to H. influenzae was indicated in 15(23%) of the 64 patients with H. influenzae present in nasopharyngeal aspirate and in 10 (3%) of the 385 patients with a negative finding. Thus, serological evidence of H. influenzae infection was demonstrated in 25 (6%) of all the 449 children with respiratory infection. Of 13 patients with cultures positive for H. influenzae acute otitis media, an antibody response was seen in only 4 (30%) patients. H. influenzae infection was associated with infections caused by other microbes in 20 children (80%), with viral infections in 60% and with pneumococcal infections in 24% of cases. An infection focus was present in 15 (79%) of the 25 patients with H. influenzae infection; pneumonia was present in 10 cases and acute otitis media in 9 cases. Non-specific laboratory evidence of bacterial infection was seen in 11 patients (58%); C-reactive protein was increased in 7 and erythrocyte sedimentation rate in 9 patients. It is concluded that non-capsulated H. influenzae is a genuine respiratory pathogen in children. H. influenzae infections appear to be secondary to preceding viral or other bacterial infections in children who are carriers of this strain.

Adolescent↗
PubMed1992

Role of Moraxella (Branhamella) catarrhalis as a respiratory pathogen in children.

During a 12-month surveillance period in 1981-1982, Moraxella catarrhalis was detected in cultures from nasopharyngeal aspirates from 76 (17%) of 449 children hospitalized with middle or lower respiratory tract infection. Seroconversion to M. catarrhalis was positive in 4 (5%) of the 76 patients with M. catarrhalis present in nasopharyngeal aspirates and in 4 (1%) of 373 patients with a negative finding. Although children with respiratory tract infections were often colonized by the organism, this was rarely the infective agent of the middle or lower airways. Four of 8 patients with seroconversion to M. catarrhalis exhibited a concomitant RSV infection. The carriage of this species was more closely associated with parainfluenza virus infections. Serological responses to M. catarrhalis were not associated with acute otitis media, and were also rare in children with pneumonia. It is concluded that bronchopulmonary infections caused by M. catarrhalis are rare in children, and that M. catarrhalis aetiology need not be considered in the selection of antibiotics in cases of community-acquired pneumonia or other infections of the middle or lower respiratory tract affecting primarily healthy children.

Adolescent↗
PubMed1992

Serologically indicated pneumococcal respiratory infection in children.

Streptococcus pneumoniae infection was indicated serologically in 84 (19%) of 449 children hospitalized with middle or lower respiratory tract infection. Pneumococcal antigen was detected in acute serum in 28 patients, but in acute urine in only 2. An antibody response to type-specific capsular polysaccharides of S. pneumoniae was indicated in 27 patients and to a protein antigen, pneumolysin, in 25 patients, but to C-polysaccharide in only 10 patients. The observations mentioned above suggest that each serological test for pneumococcal etiology is insensitive, and to get an optimal result, a large panel of pneumococcal antigen and antibody assays must be used. Pneumococcal infection could be indicated serologically although no focus of infection, such as pneumonia or acute otitis media, or no laboratory evidence of bacterial infection as elevated values of C-reactive protein concentration, erythrocyte sedimentation rate or white blood cell count was present. Particularly antibody responses to pneumococcal pneumolysin were present in children without pneumonia or acute otitis media. Our results point out that no nonspecific parameter can be used for the selection of patients with probable pneumococcal etiology among children with respiratory tract infection. Concomitant viral infection, in most cases RSV infection, was present in a third of the children with pneumococcal infection. It is concluded that pneumococcal etiology should be actively sought for also in patients with viral respiratory infection, especially in young children with RSV infection.

Adolescent↗
PubMed1992

Pneumococcal finding in a sample from upper airways does not indicate pneumococcal infection of lower airways.

The presence of pneumococcus (Pnc) by antigen detection and culture was examined in nasopharyngeal aspirates (NPA) of 315 children hospitalized with middle or lower respiratory tract infection. Pnc was found in NPA from 115 (37%) patients, being demonstrated by antigen detection alone in 34 (30%), by culture alone in 26 (23%) and by both methods in 55 (48%) of Pnc-positive samples. Pnc findings in NPA were most common, 45-46%, in patients aged 1-4 years. Serological evidence of Pnc infection, based either on detection of Pnc antigen in serum or urine, or on demonstration of an antibody response to these antigens, was present in 31 (27%) of the 115 patients with and in 28 (14%) of the 200 patients without Pnc in NPA samples. In the 48 patients positive for Pnc in NPA samples both by antigen detection and culture the isolated Pnc strains were serotyped. In 45 (94%) of these the type/group of Pnc was the same by both methods indicating that the specificity of the antigen detection tests, latex particle agglutination and counterimmunoelectrophoresis, was high. To evaluate the diagnostic significance of Pnc antigen detection and culture in NPA, sensitivity, specificity and likelihood ratios were calculated; serological evidence of Pnc aetiology was used as a reference. For both methods, sensitivity was poor, less than 0.3, but specificity was good, greater than 0.8. It is concluded that the finding of Pnc by culture or antigen detection in NPA is no indication of Pnc respiratory infection. On the other hand, Pnc etiology is unprobable, if Pnc is not present in NPA.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

The causes of hospital-treated acute lower respiratory tract infection in children.

OBJECTIVE: To determine the etiologic agents in children with acute lower respiratory infection. DESIGN: A survey of a series of patients. SETTING: General pediatric hospital serving an urban population with and without referrals in Helsinki, Finland. PARTICIPANTS: 135 Finnish children aged 2 months to 15 years (mean, 1.75 years), with clinically defined acute lower respiratory infection (with difficulty of breathing), or found to have fever and a pneumonic infiltrate on chest roentgenogram. SELECTION PROCEDURES: Consecutive sample on voluntary basis. INTERVENTIONS: None. MAIN RESULTS: Of 121 children with adequate samples, an etiologic diagnosis could be established in 84 (70%): 30 (25%) had bacterial, 30 (25%) viral, and 24 (20%) mixed infections. Antibody assays alone identified the agent in 91% of positive cases. CONCLUSIONS: Bacterial infections are common but generally underestimated in acute lower respiratory infection; serologic methods add significantly to their detection.

Acute Disease↗
PubMed1991

Bacterial infection in under school age children with expiratory difficulty.

Serological evidence of bacterial infection was prospectively studied in less than 6 years old patients during 188 acute episodes of expiratory difficulty requiring hospital treatment. Such evidence indicated by antibody or antigen assays was found in 40 patients (21%). Streptococcus pneumoniae was identified in 25 cases; antigenemia was found in 10, antigenuria in 2 and seroconversion in 14 cases. Seroconversion to nontypable Haemophilus influenzae was found in 9 and to Branhamella catarrhalis in 2 cases. Seroconversion to Chlamydia spp. was demonstrated in 8 patients, but specific tests for C. trachomatis were negative. C-reactive protein was over 40 mg/L in 35 patients (19%); serological evidence of bacterial infection was present in 14 and absent in 21 of them. Thus, either serological evidence of bacterial infection or an elevated C-reactive protein was found in 61 of the 188 cases (32%). We conclude that bacterial infection is commonly associated with acute wheezing in children under school age. We suggest that bacterial, as well as viral, infections may trigger an acute obstructive attack in children with reactive airways.

Airway Obstruction↗
PubMed1991

Serum tumor necrosis factor-alpha concentrations in children hospitalized for acute lower respiratory tract infection.

Tumor necrosis factor-alpha (TNF alpha) concentrations were measured by radioimmunoassay in sera of 118 children (median age, 1.7 years; range, 2 months-15 years) hospitalized for acute lower respiratory tract infection (ALRI). Both viral and bacterial ALRI were associated with elevated concentrations of TNF alpha. Concentrations greater than 40 ng/l were seen in children with bacterial or mixed ALRI in 64% and with viral ALRI in 50% of cases. Elevated concentrations were associated with longer duration of fever before admission (P less than .05) and with a higher serum C-reactive protein concentration (P less than .05). There were no significant differences in TNF alpha concentrations between gram-positive and gram-negative infections, nor was there an association with clinical severity of ALRI. TNF alpha concentrations decreased in most patients to normal within 5 days of hospitalization, irrespective of the etiology of the infection.

Acute Disease↗
PubMed1991

Variability of penicillin-binding proteins from penicillin-sensitive Streptococcus pneumoniae.

Penicillin-binding proteins (PBPs) from penicillin-susceptible strains of Streptococcus pneumoniae are believed to be fairly similar in contrast to PBPs occurring in resistant isolates. The antigenic variation of PBPs 1a and 2b in 65 penicillin-susceptible strains from different geographic areas and a wide variety of isolation sites was analyzed using a set of specific antisera and monoclonal antibodies. Three strains contained different antigenic variants of PBP 1a, and 50 strains contained one of three antigenic variants found in PBP 2b. Seven patterns of antibody reactivity could be defined; all but one were distinct from those found recently in resistant strains. In addition, electrophoretic mobilities of all six PBPs, compared after conventional SDS-PAGE and fluorography, revealed an unexpected variation of PBP-profiles even for strains of one sero-group. Few strains appeared identical to each other or to the laboratory reference strain R6.

Antibodies, Bacterial↗
PubMed1991

Antigenic variation of penicillin-binding proteins from penicillin-resistant clinical strains of Streptococcus pneumoniae.

Penicillin-resistant strains of Streptococcus pneumoniae that are isolated with increasing frequency worldwide contain low-affinity penicillin-binding proteins (PBPs). The relatedness of PBPs from 55 resistant strains isolated on three continents was investigated by testing the reactivity of antibodies specific for PBP 1a or 2b and by comparing the PBP patterns. Seventeen patterns of antibody reactivity could be distinguished, 12 of which were specific to one isolate. Most strains, including all German and South African strains, had a unique PBP profile. A few groups of Spanish and Finnish isolates were identified where the strains within each group shared the same PBP profile, the same antigenic variants of PBPs 1a and 2b, and the same serogroup, suggesting that they represent different clones of S. pneumoniae. The results demonstrated highly variable pathways of resistance development and confirmed that resistant strains have emerged independently in different locations.

Antibodies, Bacterial↗
PubMed1991

Reduction of oropharyngeal carriage of Haemophilus influenzae type b (Hib) in children immunized with an Hib conjugate vaccine.

The oropharyngeal carriage of Haemophilus influenzae type b (Hib) was studied among 725 healthy 3-year-old children who had or had not been immunized with an Hib conjugate vaccine. Oropharyngeal swabs were collected during the childrens' well-child visit to their local child health center. Fourteen (3.5%) of the 398 unvaccinated children were oropharyngeal carriers of Hib, whereas none of the 327 children who had received Hib conjugate vaccine carried Hib (P less than .001). Carriage rates of non-type b H. influenzae (19%) or Streptococcus pneumoniae (18%) were the same irrespective of the Hib vaccination status of the children. Thus Hib conjugate vaccine, unlike Hib polysaccharide vaccine, seems to be able to prevent oropharyngeal colonization by Hib.

Bacterial Vaccines↗
PubMed1991

Etiology of acute lower respiratory tract infections in Gambian children: I. Acute lower respiratory tract infections in infants presenting at the hospital.

Ninety infants less than 1 year of age with pneumonia and 43 control infants were investigated for viral and chlamydial infection with the use of culture and serology and for bacterial infection with the use of blood cultures, lung aspirates, antibody assays and antigen detection procedures. One or more potential pathogens were identified in 62 (69%) cases with pneumonia and in 12 (28%) controls. Infection by respiratory viruses was identified in 42 (49%) cases and in 8 (19%) controls. Respiratory syncytial virus was the commonest pathogen identified and was found in 32 cases (37%). Bacterial infections were also common, being found in 27 (30%) cases and 3 (7%) controls, and predominantly involved Streptococcus pneumoniae (20%) or Haemophilus influenzae (11%). Bacterial infections were associated with raised white blood cell counts and were identified more often by antigen detection procedures (68%) than by culture of blood or lung aspirates (34%) or by serology (33%). Mixed viral-bacterial infections were identified in 13 cases (15%). Infection with Chlamydia trachomatis was diagnosed in 2 infants with acute lower respiratory tract infection and in 1 control infant.

Acute Disease↗
PubMed1991

Etiology of acute lower respiratory tract infections in Gambian children: II. Acute lower respiratory tract infection in children ages one to nine years presenting at the hospital.

Seventy-four children ages 1 to 9 years hospitalized because of severe pneumonia were investigated using blood cultures, lung aspirates, nasopharyngeal aspirates, serology and antigen detection procedures. A bacterial infection was identified in 57 (77%), a viral infection was seen in 25 (34%) and 18 (24%) had mixed viral-bacterial infections. The bacterial pathogens most frequently identified were Streptococcus pneumoniae and Haemophilus influenzae found in 61 and 15% of patients, respectively. The viral pathogen most frequently recovered was respiratory syncytial virus (12%). Evidence of Chlamydia pneumoniae strain TWAR and Mycoplasma pneumoniae infection was found in 12 and 4% of cases, respectively. Overall a potential pathogen was identified in 60 (81%) children, with evidence of polymicrobial infection in 30 cases (40.5%). The study provides information on the relative role of different infectious agents in the etiology of severe pneumonia in children in a developing country.

Acute Disease↗