Diagnosis of Mycoplasma pneumoniae pneumonia in pediatric patients by polymerase chain reaction (PCR)

Polymerase chain reaction (PCR) testing was performed on respiratory tract specimens obtained by throat swab in 21 children admitted to the hospital with suspected Mycoplasma pneumoniae pneumonia. Of 13 patients with a clinical condition compatible with mycoplasma infection and an immunological response to M. pneumoniae, 11 were positive by PCR. Eight patients were negative by serology and/or had a clinical condition not compatible with mycoplasma infection, and all were negative by PCR. The antibody response to M. pneumoniae was delayed for a week or more in 3 (23%) of the 13 patients with documented mycoplasma infection. These results suggest that PCR performed on a respiratory tract specimen obtained by a throat swab may be useful in the initial evaluation of children with suspected M. pneumoniae pneumonia, especially in patients in whom the serological response is delayed.     

Evaluation of PCR, culture, and serology for diagnosis of Chlamydia pneumoniae respiratory infections

We prospectively studied 156 patients with a diagnosis of community-acquired pneumonia requiring admission. Several respiratory specimens were obtained for the detection of Chlamydia pneumoniae by cell culture and PCR. Three serum samples were obtained from each patient. Serological diagnosis of a C. pneumoniae infection was determined by the microimmunofluorescence (MIF) test, the complement fixation (CF) test, and recombinant lipopolysaccharide (LPS) enzyme-linked immunosorbent assay (ELISA; referred to as the rDNA LPS ELISA). Twenty-three patients (15%) had serological results compatible with acute C. pneumoniae infection; nine (39%) of these subjects were C. pneumoniae PCR positive. Twenty-two patients (14%) had positive PCR results without serological evidence of an acute C. pneumoniae infection. An attempt was made to calculate the sensitivities and specificities of the MIF test, rDNA LPS ELISA, and PCR for the diagnosis of chlamydial community-acquired pneumonia. Several "gold standards" were defined. Generally, the sensitivities of the rDNA LPS ELISA and MIF were comparable, while the sensitivity of the CF test was shown to be very low. Independent of the gold standard used, the best PCR results were obtained with nasopharyngeal specimens. However, the predictive value of a positive C. pneumoniae PCR result for patients with community-acquired pneumonia remains unknown and may be low. Although a widely accepted gold standard is still lacking, the rDNA LPS ELISA may currently be the preferred tool for diagnosing acute respiratory Chlamydia infections in routine clinical practice. However, the MIF test remains the method of choice for determining the prevalence of C. pneumoniae infections in a given community.     

Value of assessing cryptococcal antigen in bronchoalveolar lavage and sputum specimens from patients with AIDS

Cryptococcus neoformans has become a significant opportunistic pathogen, accounting for 8-10% of infectious complications in patients with AIDS. When encapsulated yeast cells are observed in Giemsa-stained smears of bronchoalveolar washings (BAL), or induced sputum specimens, confirmation as C. neoformans is germane to definitive therapy. We therefore studied 30 BAL and 9 induced sputum specimens for cryptococcal antigen. Of the 30 BAL, 3 specimens were positive for cryptococcal antigen, ranging in titer from 1:4 to 1:256, and 2 of 9 sputum samples were also smear, culture and antigen positive (titer 1:2) for C. neoformans. Of the 34 negative specimens, none of the seven containing Candida species or the one containing H. capsulatum or the one containing P. carinii cross-reacted with cryptococcal anticapsular antibody. Our results indicate that when yeast forms suggestive of C. neoformans are visualized on direct smears of BAL or sputum samples, rapid confirmation as C. neoformans may be achieved by assessment for cryptococcal antigen. A correlation may also exist between antigen titer in respiratory specimens and extent of cryptococcal infection.     

Detection of serum antibodies against Chlamydia pneumoniae by ELISA

Chlamydia pneumoniae causes pneumonia and other respiratory infections in children, adolescents and adults. We tried to evaluate the diagnostic value of detection of serum antibodies by ELISA for C. pneumoniae infections in Japanese children. Serum IgG, IgA and IgM antibodies to C. pneumoniae were determined by the microimmunofluorescence (MIF) test. Serum IgG and IgA antibodies were also determined by ELISA test kits. Results obtained by ELISA were compared with those obtained by MIF test. IgG antibody to C. pneumoniae was detected in 135 (39.5%) by ELISA and in 125 (36.5%) by MIF out of 342 sera from Japanese infants and children without respiratory infections (aged from 2 months old to 15 years old). IgA antibody to C. pneumoniae was detected in 129 (37.7%) by ELISA and in 117 (34.2%) by MIF out of 342 sera tested. Of 342 specimens 113 were IgG-positive by ELISA and MIF (sensitivity: 90.4%, specificity: 89.9%, r = 0.853). Of 342 sera 28 had IgG antibody titers of 1:256 and none had titers 1:512 or higher by MIF. Of 28 infants and children a total of nine were less than 4 years of age. On the other hand, of 342 specimens 99 were IgA-positive by ELISA and MIF (sensitivity: 84.6%, specificity: 86.7%, r = 0.769). Of 342 sera 16 had IgA antibody titers of 1:256 or higher by MIF. Of 16 infants and children, ten were less than 4 years of age. ELISA had excellent sensitivity and specificity relative to MIF test for detection of IgC and IgA antibodies to C. pneumoniae. It was suggested that C. pneumoniae infection in Japanese infants and children under 4 years of age was not infrequent.     

Usefulness of bronchoalveolar lavage in the renal transplant patient with suspected respiratory infection

In this retrospective study we aimed to assess the diagnostic yield of bronchoalveolar lavage (BAL) in kidney transplant patients who were suspected of having severe respiratory infection or in whom empirical antibiotic treatment had failed. All BAL procedures performed on kidney transplanted patients suspected of having respiratory infections between January 1, 1988 and July 31, 1996 were analyzed. BAL was carried out in the standard way and samples were sent for cytologic and bacteriologic study. Thirty-three patients with a mean age of 48.5 years were enrolled. All had been receiving immunosuppressive treatment and the mean time following transplantation was 320 days. Thirty-one had received antibiotic treatment before BAL. BAL was positive for 21 of the 33 patients (64%). Twenty-two pathogens were identified: 6 Pneumocystis carinii, 4 Cytomegalovirus, 3 Mycobacterium tuberculosis, 2 Aspergillus fumigatus, 2 Herpes simplex type I, 1 Streptococcus pneumoniae, 1 Staphylococcus aureus, 1 Streptococcus mitis, 1 Legionella pneumophila, 1 Legionella longbeachae. BAL was negative for 12 patients, of whom 8 were tentatively diagnosed of bacterial infection, 3 of acute pulmonary edema and one of pulmonary infarction. Based on the results, therapy was changed for 20 patients (61%), 19 (58%) because an unsuspected pathogen was identified and 1 because treatment could be simplified. The diagnostic yield of BAL is high (64%) in kidney transplant patients suspected of respiratory infection and is useful for managing such cases, as evidenced by the fact that a high proportion (19/33) of our patients were infected by pathogens not covered by empirical treatment.     

Experimentally induced Mycoplasma pneumoniae pneumonia in chimpanzees

Eight chimpanzees were examined. Two served as negative control and six inoculated with Mycoplasma pneumoniae became colonized. Colonization persisted for 28-68, 16-50 and 21 days with an average duration of 47, 32.5 and 21 days in the oropharyngeal, tracheal and lung tissues, respectively. Mycoplasma titers ranged from 10(8) to 10(1) color-changing units per specimen during the course of the infections. Seroconversion occurred within 12-15 days and peak antibody titers ranged from 1.256 to 1.1024 and developed between days 28 and 48 post-inoculation. Positive cold agglutinin titers were detected between 12 to 15 days and peak titers ranged from 1:80 to 1:640. Significant increases in sIgA and IgG immunoglobulin antibody levels were detected in lung lavage fluids. Unlike the many other experimentally infected animals examined, chimpanzees infected with M. pneumoniae had positive X-ray findings, developed cold agglutinins and showed overt signs of disease. These signs include persistent cough, low grade fever, rhinitis, oropharyngitis, diarrhea, and loss of appetite. Peak severity of disease corresponded with peak lung colonization, and the detection of cold agglutinins and positive X-ray findings. The microbiological, serological and clinical aspects of pneumonia induced in chimpanzees was similar to naturally occurring primary atypical pneumonia in humans.     

Repeatability of treadmill exercise ejection fraction and wall motion using technetium 99m-labeled sestamibi first-pass radionuclide ventriculography

Bacterial antibodies were studied in acute, intermediate and convalescent phase sera (mean duration from first to last sample 36 days) of 121 children hospitalized for acute lower respiratory tract infection. Antibody responses were observed in 45% of all cases and in 29% of the 21 children < 1 year old. A total of 15 responses to Streptococcus pneumoniae (pneumolysin), 20 to Haemophilus influenzae, 9 to Moraxella catarrhalis, 3 to chlamydiae and 8 to Mycoplasma pneumoniae were found. In 79 patients with 4 consecutive samples available, 52% of the 31 responses were measurable within 5 days from admission. Overall the responses were not associated with upper respiratory tract bacterial findings or acute otitis media. Significantly more responses were found in the 121 children with acute lower respiratory tract infection than in healthy controls (P < 0.007). We conclude that bacterial antibody assays provide a useful tool in the study of the etiology of acute lower respiratory tract infection in young children, even if the interval between paired serum samples is short.     

Comparison of bronchoalveolar lavage and catheter lavage to confirm ventilator-associated lower respiratory tract infection

Lower respiratory tract infection (LRTI) is a well recognised complication of artificial ventilation in intensive care units (ICU). Ideally, specimens for microbiological analysis should be obtained during bronchoscopy, but this is not always possible. Therefore, the microbiological diagnosis of lower respiratory tract infection by broncho-alveolar lavage (BAL) obtained during bronchoscopy was compared with catheter lavage (CL) with a balloon-tipped catheter. Adult patients with clinical evidence of lower respiratory tract infection in an adult ICU were randomly assigned to undergo BAL followed by CL or vice versa. Forty ml of normal saline 0.9% were instilled and then aspirated with a flexible bronchoscope to obtain BAL. A similar volume was instilled and aspirated with a 12-gauge Foley balloon-tipped catheter to obtain a CL sample. The number of inflammatory cells, epithelial cells and organisms seen by microscopy were quantified. Culture results were semi-quantified and classified as negative, positive, equivocal or contaminated. Seventy-nine paired specimens were obtained from 66 patients, including specimens from 10 patients taken on two or more occasions. Only 20% of BAL and 16% of CL had one or more epithelial cells and bacteria were seen in 26 BAL and 21 CL specimens, respectively; 35% of BAL and CL specimens were positive and there was a discrepancy in the culture result in only two cases. Staphylococcus aureus was the pathogen isolated most frequently and polymicrobial lower respiratory infection was diagnosed on 10 occasions (15%). CL fluid is as reliable as BAL in diagnosing lower respiratory tract infection in ICU. This approach does not require bronchoscopic expertise and utilises convenient laboratory techniques.     

Serological diagnosis of experimental Enterococcus faecalis endocarditis

A modified rat model of endocarditis with catheterization for 2 days was established in female Lewis rats using different inocula of Enterococcus faecalis (strain no. EF 19) in order to measure IgG antibodies in serum during the course of infection. Increasing the inocula intravenously resulted in an increase in the CFU/g vegetation and the CFU/g spleen, the ID50 being about 10 CFU/ml and the ID90 about 1x10(2) CFU/ml. The lowest bacterial inoculum infecting 100% of the rats was 3x10(3) CFU/ml, and for further investigations we used this inoculum size. Rats were sacrificed on day 2, 5, 7, 9, 11 and 28 after infection. The CFU/g vegetation and the CFU/g spleen increased until day 7 and then decreased. Serum samples were collected from 129 rats at different times after challenge. Three different ELISA systems were established to measure the IgG antibody responses: E. faecalis sonicate ELISA (a pool of four sonicates of strain no. EF 10, EF 11, EF 19 and EF 48), E. faecalis whole cell ELISA (strain no. EF 19) and E. faecalis purified cell wall ELISA (strain no. EF 19). An IgG antibody response was detected already on day 2, and except for a minor decrease on day 6/7 the antibody response continued to increase until day 14 (whole cell ELISA and sonicate ELISA) and day 21 (purified cell wall ELISA) when a plateau was reached. Significant increases in IgG antibody responses (p<0.05) were found between groups of rats from days 0-2, 2-8/9 and 8/9-14 in the E. faecalis whole cell and sonicate ELISAs and from days 0-2, 2-10/11 and 10/11-21 in the E. faecalis purified cell wall ELISA. In conclusion, we established a model of endocarditis in rats with catheterization for 2 days and were able to demonstrate an increase in IgG antibodies during the course of infection.     

In vivo anti-influenza virus activity of Kampo (Japanese herbal) medicine "sho-seiryu-to"--stimulation of mucosal immune system and effect on allergic pulmonary inflammation model mice

When BALB/c mice were treated with a Kampo (Japanese herbal) medicine "Sho-seiryu-to (SST)" (1 g/kg, 10 times) orally from 7 days before to 5 days after the infection and infected with mouse-adapted influenza virus A/PR/8/34 by nasal-site restricted infection, SST caused increment of the influenza virus hemagglutinin-specific IgA antibody secreting cells in nasal lymphocyte but not in Peyer's patch lymphocyte at 6 days after infection in comparison with water-treated mice. Oral administration of SST also augmented IL-2 receptor beta chain+ (activated) T-cell in Peyer's patch lymphocyte, but not in the nasal lymphocyte. We previously reported that SST showed potent anti-influenza virus activity through augmentation of the antiviral IgA antibody titer in the nasal and broncho-alveolar cavities of the mice (T. Nagai and H. Yamada, 1994, Int. J. Immunopharmacol. 16, 605-613). These results suggest that oral administration of SST shows anti-influenza virus activity in the nasal cavity by activation of T-cell in Peyer's patch lymphocyte and stimulation of production of anti-influenza virus IgA antibody in nasal lymphocyte. When ovalbumin-sensitized allergic pulmonary inflammation model mice were administered orally with SST (1 g/kg) from 8 days before (11 times) or from 2 h after (4 times) to 4 days after the infection and infected with mouse-adapted influenza virus A/PR/8/34, replications of the virus in the both nasal and broncho-alveolar cavities or only nasal cavity were significantly inhibited at 5 days after infection in comparison with water-treated control by augmenting antiviral IgA antibody, respectively. These results suggest that SST is useful for both prophylaxis and treatment of influenza virus infection on patients with allergic pulmonary inflammation, such as bronchial asthma.     

Level of viral antigen in blood leucocytes from cattle acutely infected with bovine viral diarrhoea virus

Blood samples from 24 calves undergoing experimental acute infection with a non-cytopathogenic bovine viral diarrhoea virus (BVDV) were examined for viral antigen in peripheral leucocytes with an enzyme-linked immunosorbent assay (ELISA), and for presence of virus in blood plasma in a cell culture assay. With the antigen ELISA, low positive values were detected in leucocytes sampled on days 3-4 from two of eight animals inoculated intranasally, and on days 11-13 from three of 16 animals inoculated intramuscularly. From 22 of the animals, low titres of BVDV were detected in blood plasma obtained 2-9 days after inoculation. All other samples, drawn between 2 and 21 days after inoculation, were negative for viral antigen. All animals seroconverted 3-4 weeks after inoculation, some after having shown mild and transient signs of disease.     

Small volume bronchoalveolar lavage used in diagnosing Pneumocystis carinii pneumonia in HIV-infected patients

To determine the volume of bronchoalveolar lavage (BAL) fluid necessary to diagnose Pneumocystis carinii pneumonia (PCP) in immunocompromised patients, specimens from 25 patients were evaluated. Twenty-one patients were HIV infected. BAL was performed using three to four 60-mL aliquots of room temperature, sterile, saline solution. Each syringe of BAL effluent was numbered and its volume was measured. Immunofluorescent stains were performed on about 8-mL aliquots of the initial, final, and aggregate BAL specimens, and a modified Giemsa stain was also performed on a 0.4-mL aliquot of the aggregate specimen. Of 25 patients, Pneumocystis carinii organisms were identified in 9 with HIV infection, in whom all BAL specimens were positive with both immunofluorescence and Giemsa stains. In 16 patients, BAL specimens were negative for P carinii on both immunofluorescent and modified Giemsa testing. Both staining methods were 100% specific (95% confidence interval [CI], 83 to 100%) and 100% sensitive (95% CI, 72 to 100%). The volume of BAL effluent in the initial specimens positive for P carinii ranged from 15 to 25 mL. We conclude that in this small group of patients, PCP was accurately diagnosed from a single 60-mL BAL specimen stained with immunofluorescence methods.     

Long-term results after repeated surgical removal of pulmonary metastases

A 14-year-old boy developed acute transverse myelitis with severe abdominal pain, bladder dysfunction, weakness, and sensory loss of the lower extremities. Magnetic resonance imaging revealed a segmental expanded central edema affecting parts of the spinal cord, including the caudal medulla oblongata. Antibody response to Mycoplasma pneumoniae was negative in microparticle agglutination assays (1:40 in the acute serum and 1:160 in the convalescent serum) and complement fixation tests (1:20 and 1:10). However, analysis of acute-phase serum revealed a specific IgA and IgG response but no IgM response. Detection of M. pneumoniae in the cerebrospinal fluid by nested polymerase chain reaction and in nasopharyngeal aspirate by culture confirmed an M. pneumoniae infection. Treatment with doxycycline (100 mg daily) was started on the second day after admission to the hospital and continued for 14 days; the patient recovered completely and was discharged 20 days after onset of the disease, with no signs of neurological deficits.     

Confirmed previous infection with Chlamydia pneumoniae (TWAR) and its presence in early coronary atherosclerosis

BACKGROUND: Chlamydia pneumoniae has been identified in coronary atheroma, but concomitant serum antibody titers have been inconsistently positive and unavailable before the detection of early or advanced atherosclerotic lesions. METHODS AND RESULTS: This retrospective investigation was performed on premortem serum specimens and autopsy tissue from 60 indigenous Alaska Natives at low risk for coronary heart disease, selected by the potential availability of their stored specimens. Serum specimens were drawn a mean of 8.8 years (range, 0.7 to 26.2 years) before death, which occurred at a mean age of 34.1 years (range, 15 to 57 years), primarily from noncardiovascular causes (97%). Coronary artery tissues were independently examined histologically and, for C pneumoniae organism and DNA, by immunocytochemistry (ICC) and polymerase chain reaction (PCR) with species-specific monoclonal antibody and primers. Microimmunofluorescence detected species-specific IgG, IgA, and IgM antibody in stored serum. C pneumoniae, frequently within macrophage foam cells, was identified in coronary fibrolipid atheroma (raised lesions, Stary types II through V) in 15 subjects (25%) and early flat lesions in 7 (11%) either by PCR (14, 23%) or ICC (20, 33%). The OR for C pneumoniae in raised atheroma after a level of IgG antibody > or =1:256 >8 years earlier was 6.1 (95% CI, 1.1 to 36.6) and for all coronary tissues after adjustment for multiple potential confounding variables, including tobacco exposure, was 9.4 (95% CI, 2.6 to 33.8). CONCLUSIONS: Serological evidence for C pneumoniae infection frequently precedes both the earliest and more advanced lesions of coronary atherosclerosis that harbor this intracellular pathogen, suggesting a chronic infection and developmental role in coronary heart disease.     

Mycoplasma pneumoniae detection from throat swab by two-step polymerase chain reaction

Two-step polymerase chain reaction (PCR) with primers designated against 16S rRNA gene of Mycoplasma pneumoniae for diagnosis of infection was evaluated in comparison with the conventional single-step PCR and culture methods. The two-step PCR method showed specific amplification of M. pneumoniae DNA and higher sensitivity (1.5 fg/assay) than the single-step PCR method. With the two-step PCR method, 76 of 322 throat swabs (23.6%) from patients with acute respiratory complaints gave positive results whereas 20.2% were positive in the culture method. Seven of 13 samples which were negative in the single-step PCR method but positive in either serological or the culture method showed positive results by the two-step PCR method. In addition, 5 samples which were weakly positive in the single-step PCR method showed distinctly positive results in the two-step PCR. These results indicate that the two-step PCR method is a useful tool for detection of M. pneumoniae in clinical specimens, although it requires a relatively sophisticated in technique.     

Comparison of two serological methods and a polymerase chain reaction-enzyme immunoassay for the diagnosis of acute respiratory infections with Chlamydia pneumoniae in adults

Chlamydia pneumoniae is a common respiratory tract pathogen. Serological methods currently used for the diagnosis of C. pneumoniae infection lack specificity, give ambiguous results from a single serum sample and often provide only a retrospective diagnosis. A prospective study was undertaken to assess whether PCR could be a useful addition to the serological techniques routinely practised for diagnosis. This study investigated 68 adult patients with a diagnosis of acute respiratory infection. Acute and convalescent serological determination of antibodies to C. pneumoniae were performed by means of an rELISA test and a micro-immunofluorescence (MIF) test. Nasopharyngeal aspirates or bronchoalveolar lavage specimens and bronchial aspirates obtained from the 68 patients were evaluated by PCR-enzyme immunoassay (PCR-EIA) for the presence of C. pneumoniae and by immunofluorescence assay and cell culture for virus identification. Mycoplasma pneumoniae serology was also performed. Eight patients (11.8%) were positive by either rELISA or PCR-EIA, or both, with an infection rate of 5 (18.5%) of 27 in patients with community-acquired pneumonia, 2 (9%) of 22 in asthmatic patients and 1 (5%) of 19 in patients with an exacerbation of chronic obstructive pulmonary disease. Serological evidence of acute infection was found in four of these patients with the rELISA test and in three others with the MIF test. PCR-EIA detected C. pneumoniae DNA in four specimens, but there were concordant results with both rELISA and PCR-EIA in only one patient A positive PCR-EIA was also obtained in a patient who did not show an antibody response in acute serum. The discrepancy between serological and PCR-EIA results reflects the difficulties in routine laboratory diagnosis of C. pneumoniae infection and the necessity for further studies with optimised techniques.     

A comparative study of nucleolar organizer region, proliferating cell nuclear antigen and epidermal growth factor receptor staining in colon tumours

The prevalence of hepatitis A virus (HAV) antibody in people has decreased from year to year in Japan. A sequential outbreak occurred in an institution for the mentally handicapped people in Chiba City in the summer of 1995. Eight people were infected including 7 residents and one staff member. We tested to detect antigen in fecal samples by ELISA and PCR for early diagnosis for hepatitis A infection. Four sera and 5 feces were obtained from 5 patients between 2 and 8 days after the onset of symptoms. The anti-HAV IgM was found to be positive in 4 sera examined. The HAV antigen was detected in 3 out of 5 feces using ELISA. An existence of inhibitor in 2 negative specimens against the ELISA was suggested by the recovery test of added antigen. HAV RNA was extracted by CTAB method from feces and detected in 4 our of 5 specimens in PCR amplification and in all of 5 specimens in nested PCR amplification. The sequence of PCR products in the P1/P2 junction of the HAV genome revealed that the virus associated with the outbreak belongs to HAV subgenotype IA. HAV RNA was detected in ELISA negative specimens and in the specimen from a patient 2 days after the onset of symptoms using PCR amplification by CTAB method. These results indicate that PCR amplification was useful for the early diagnosis of hepatitis A infection.     

Pharmacokinetic study in rats after single intravenous and oral administrations of [14C]-ITF-296

Fifteen mycoplasma-free chickens were contact exposed to five chickens that had been experimentally infected with one of three different strains (two field strains and one laboratory strain) of Mycoplasma synoviae (MS). Culture and polymerase chain reaction (PCR) were positive by 3 days postinoculation (PI) in the experimentally infected birds. Lateral transmission was found by 7-14 days postexposure. Positive serum plate agglutination (SPA) results were detected 3-4 wk after positive culture and/or PCR in individual birds. By 42 days PI, all the birds in the groups exposed to field strain K1858 or K3344 had become infected as determined by culture and PCR, whereas only half of the birds in the group exposed to laboratory strain WUV1853 had become infected. Because of the unanticipated lack of seroconversion to hemagglutination inhibition (HI) and enzyme-linked immunosorbent assay (ELISA) in infected chickens, the study was extended. Each group was split into two groups of 10 birds each, one of which was vaccinated with a live B1/LaSota Newcastle disease (ND) vaccine virus to determine if a viral respiratory challenge might incite a stronger antibody response to the mycoplasma infection. All the birds were tested for seroconversion 14 and 21 days later. Of the birds vaccinated for ND, a slightly greater number were MS positive by SPA than the nonvaccinated birds. This effect was not present 21 days after vaccination, and there was no significant difference in the MS HI results from these groups, suggesting that the viral respiratory infection had little direct impact on seroconversion. The virulent field strain (K3344) elicited a stronger MS antibody response than the other strains. All results from the MS ELISA were negative in all groups through 9 wk. Positive results from PCR analysis correlated well with culture results, whereas serologic tests did not detect MS infection for several weeks. Monitoring programs solely dependent on seroconversion may be inadequate for diagnosis and control of mycoplasma infections.     

Oligonucleotide-poly-L-ornithine conjugates: binding to complementary DNA and RNA

A lysate of human herpesvirus type 6 (HHV6) infected HSB2 cells was used as antigen for an enzyme-linked immunosorbent assay (ELISA) for the detection of IgG and IgM antibody to HHV6. 78 clinical samples were tested for the presence of HHV6-specific IgM. Nine specimens, all from children under 4.5 years of age, were found to be reactive indicating probable acute infection with HHV6. Sera from 12 healthy adult blood donors and from 88 of 90 adults over the age of 35 with unspecified health conditions tested negative for HHV6 IgM, indicating a minimum specificity estimate of nearly 98% in these patients. Cross-reactivity of antibody to other herpes viruses with the HHV6 ELISA antigen was not detected. Six hundred and ninety-six serum samples from individuals of different age groups were examined for IgG antibody status. In 94% of these samples, IgG antibody was detected. Our data suggests that most Canadians possess antibody to HHV6 by 1 yr of age and that on average, antibody levels remain high through early adulthood but begin to decline with advancing age. The ELISA described is a reliable test for the measurement of IgG and IgM antibodies for both clinical diagnosis and epidemiological studies.     

Etiology of childhood pneumonia: serologic results of a prospective, population-based study

BACKGROUND: To investigate the etiology of pediatric community-acquired pneumonia, we conducted a prospective, population-based study covering the total population <15 years of age (n = 8851) in 4 municipalities in eastern Finland. MATERIALS AND METHODS: The number of patients was 201; chest radiographs were available for all cases and paired sera for serologic assays were available for >90% of cases. The methods included assays for antibody response to 3 pneumococcal antigens, specific pneumococcal immune complex assays and conventional antibody tests for mycoplasmal, chlamydial and viral infections. RESULTS: Serologic evidence of specific microbial etiology was obtained in 133 (66%) of the pneumonia patients. Bacterial infection was diagnosed in 102 cases (51%) and viral infection in 51 cases (25%). Streptococcus pneumoniae was the most common agent (57 cases; 28%), followed by Mycoplasma pneumoniae (44; 22%), respiratory syncytial virus (43; 21%) and Chlamydia spp. (29; 14%). Haemophilus influenzae was identified in only 6% and Moraxella catarrhalis in only 3% of the children. More than one specific infection was found in 51 patients (25%). The proportion of pneumococcal cases varied from 24 to 36% by age. Mycoplasma infections were seen mostly in patients > or =5 years and Chlamydia infections in patients > or =10 years of age. CONCLUSIONS: The results of our prospective, strictly population-based study confirm the importance of S. pneumoniae in the etiology of community-acquired pneumonia in children of all ages. M. pneumoniae and Chlamydia pneumoniae are important from the age of 5 years onwards.