Respiratory Chlamydia Research Articles

Mouse model of respiratory Chlamydia pneumoniae infection for a genomic screen of subunit vaccine candidates

An inbred A/J mouse respiratory challenge model was validated for vaccine testing against Chlamydia ( C.) pneumoniae and used to screen the C. pneumoniae genome for vaccine candidates by expression library immunization (ELI). Biolistic delivery of genetic vaccine constructs elicited Th2-like immunity that was associated with inefficient elimination of C. pneumoniae. Delivery by injection elicited protective Th1-like responses. Since biolistic delivery of pools of ORFs was used in first round screening, the screen presumably selected against potent immunogens. Nevertheless, it was sufficiently accurate to identify three weakly protective antigens among all putative C. pneumoniae ORFs. The results suggest ELI discovery of highly protective C. pneumoniae vaccine candidates requires tight control of the Th1 immunity elicited by the genetically delivered library of test antigens.

Legionella waltersii–a novel cause of pneumonia?

A 5-y-old girl was admitted to our hospital with fever, cough, respiratory distress and rapidly increasing oxygen requirements. A chest radiograph showed bilateral central infiltrates. PCR was performed with pharyngeal washings and revealed Legionella DNA, while no genetic materials of other pathogens such as respiratory viruses, Mycoplasma and Chlamydia were detected. The clinical condition improved gradually after administration of steroids and therapy with clarithromycin. Further sequencing of Legionella DNA led to the identification of Legionella waltersii. This Legionella species has never been described as a human pathogen before. For the first time, L. waltersii was identified as a cause of severe pneumonia. Since L. waltersii is not detected by routine laboratory tests, it may be speculated that these bacteria, like other Legionella species, are underestimated as a probable cause of community-acquired pneumonia.

Frequency of Detection of Picornaviruses and Seven Other Respiratory Pathogens in Infants

Previous studies in which molecular-based techniques have been used to identify the causative pathogens of respiratory tract infection have investigated hospitalized children only. We report a prospective study designed to determine the frequency and clinical presentation of community-acquired respiratory illness in infancy associated with 8 common respiratory pathogens. Eighty-eight infants were monitored through their first winter. With each respiratory illness, infants were examined, and a nasal lavage specimen was collected. Individual reverse transcription-polymerase chain reactions were performed to detect infection with picornaviruses (rhinoviruses and enteroviruses), coronaviruses (serotypes OC43 and 229E), adenoviruses, parainfluenza viruses 1-3, influenza viruses (types A and B), respiratory syncytial virus (RSV), Chlamydia pneumoniae and Mycoplasma pneumoniae. Picornaviruses were the most frequently detected pathogen identified in 46% (56 of 123) of episodes, followed by RSV (27%), parainfluenza viruses (13%) and coronaviruses (9%). Dual pathogen infections were identified in 20% of episodes, predominantly caused by picornaviruses together with either RSV or parainfluenza viruses. RSV infection was significantly associated with a diagnosis of bronchiolitis. No other associations were found between pathogen and clinical diagnosis. Dual infection did not predispose infants to a more severe clinical course. Picornaviruses are the predominant cause of community-acquired respiratory tract infection in the first year of life. Large prospective community-based studies will be needed to fully evaluate the contribution of picornaviruses, both in isolation and in combination with other respiratory pathogens, to the various clinical syndromes of respiratory infection observed during infancy.

Coxiella burnetii and Atypical Respiratory Infectious Burden in Stroke

To the Editor: We have previously reported the seroprevalence of 3 common atypical respiratory pathogens, Chlamydia pneumoniae , Mycoplasma pneumoniae , and Legionella pneumophila , in case-control studies involving an elderly cohort of stroke/transient ischemic attack (TIA) and medical patients.1 We concluded that the risk of stroke/TIA appeared to associate with the aggregate number of chronic infectious burden of these atypical respiratory pathogens.1 We have now determined the seroprevalence (immunoglobulins, IgG and IgM) of Coxiella burnetii , another well-recognized atypical respiratory pathogen in this same cohort of patients. Using commercial enzyme-linked immunosorbent assay (ELISA) kits (PANBIO Ltd), the seropositivity of Coxiella burnetii IgG was found in 2 (2.4%) out of the 85 ischemic stroke/TIA …

Aetiology of acute pharyngitis: the role of atypical bacteria.

In order to establish the role of atypical bacteria and compare characteristics of different infectious agents in acute pharyngitis, 127 patients with acute pharyngitis (66 males; median age, 5.33 years; range, 6 months to 14 years) and 130 healthy subjects of similar sex and age were studied. Serology with paired samples and PCR on nasopharyngeal aspirates and throat cultures were used to identify bacteria and viruses. Viruses were identified in 43 patients (33.8%) and five controls (3.8%; P < 0.0001), potential bacterial pathogens in 34 patients (26.8%) and 26 controls (20%; P = 0.256) and mixed viral/bacterial pathogens in 26 patients (20.5%) and none of the controls (P < 0.0001). The main aetiological agents were adenovirus, respiratory syncytial virus (RSV), Mycoplasma pneumoniae, Streptococcus pyogenes and Chlamydia pneumoniae. M. pneumoniae was the agent found most frequently as a single pathogen. A history of recurrent pharyngitis, having older siblings and a negative outcome were significantly more common among patients with acute M. pneumoniae infection than among those with infections due to other pathogens or healthy controls. This study demonstrates that: (i) adenovirus and RSV have a prominent role in acute pharyngitis; (ii) S. pyogenes is found frequently, but it is not possible to distinguish simple carriers from patients with a true infection; (iii) M. pneumoniae appears to be able to cause acute pharyngitis per se; and (iv) C. pneumoniae seems to be mainly a co-pathogen. To avoid the risk of an incorrect therapeutic approach, simple laboratory investigations that allow rapid identification of M. pneumoniae infections are urgently needed.

Evaluation of an automated complement-fixation test (Seramat) for diagnosis of acute respiratory infections caused by viruses and atypical bacteria

The complement-fixation test (CFT) permits low-cost screening of serum samples for different agents within a single assay, and is a useful tool for the serological diagnosis of acute respiratory infections. This study evaluated the automated Seramat CFT system with 160 paired serum samples taken from 80 patients with acute respiratory infection in comparison with in-house CFTs against a panel of agents, including influenza A and B, adenovirus, respiratory syncitial virus, cytomegalovirus, Mycoplasma pneumoniae, Coxiella burnetti and Chlamydia spp., and in comparison with indirect immunofluorescence (IIF) against Legionella pneumophila. Overall, the Seramat system identified 75 (88.2%) of the 85 seroconversions recognised by in-house CFTs or IIF. In comparison to the in-house CFTs, the correlation was 89.2% (66/74). For L. pneumophila, the Seramat system detected nine (81.8%) of the 11 cases diagnosed by IIF. The Seramat system also identified eight additional seroconversions that were not detected by the in-house assays; none of these seroconversions was detected by the in-house assay on retesting. The Seramat system represents a significant technical improvement that may enable many clinical laboratories to use the CFT as a routine diagnostic tool.

Environmental NO2 Raises Severity of Virus-induced Asthma

Epidemiology| September 01 2003 Environmental NO2 Raises Severity of Virus-induced Asthma AAP Grand Rounds (2003) 10 (3): 29–30. https://doi.org/10.1542/gr.10-3-29 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Cite Icon Cite Search Site Citation Environmental NO2 Raises Severity of Virus-induced Asthma. AAP Grand Rounds September 2003; 10 (3): 29–30. https://doi.org/10.1542/gr.10-3-29 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search nav search search input Search input auto suggest search filter All PublicationsAll JournalsAAP Grand RoundsPediatricsHospital PediatricsPediatrics In ReviewNeoReviewsAAP NewsAll AAP Sites Search Advanced Search Topics: asthma Source: Chauhan AJ, Inskip HM, Linaker CH, et al. Personal exposure to nitrogen dioxide (NO2) and the severity of virus-induced asthma in children. Lancet. 2003;361:1939–1944. Investigators from the University of Southampton and Imperial College, London, England assessed whether there is a relationship between nitrogen dioxide (NO2) exposure and the severity of childhood asthma exacerbations due to documented viral infections. In a cohort of 114 children aged 8–11 years, daily upper and lower respiratory tract symptoms, peak expiratory flow, and weekly personal NO2 exposure measurements were followed for up to 13 months. Children of smokers were excluded. Nasal aspirates during reported upper respiratory tract illness were tested for common respiratory viruses, Chlamydia pneumoniae, and Mycoplasma pneumoniae. Exposure to NO2 Exposure to in the week before or after upper respiratory tract infection was divided into tertiles and analyzed in... You do not currently have access to this content.

Respiratory symptoms, asthma, atopy and Chlamydia pneumoniae IgG antibodies in a general population sample of young adults.

This study was designed to test the association of Chlamydia pneumoniae infection with respiratory symptoms and atopy. A general population sample of 369 young adults (aged 20-44 years) completed a questionnaire on respiratory symptoms and underwent skin prick testing. C. pneumoniae IgG and IgM serum titers were measured by microimmunofluorescence. Prior infection was defined by titers of IgG > or = 1:32, acute infection by titers of IgG > or = 1:512 and/or IgM > or = 1:16. The prevalence of cough and phlegm was higher in subjects with (19.0%) than in those without (11.4%) prior C. pneumoniae infection (p = 0.01). A similar difference was found for wheezing (14.3% vs 8.0%; p = 0.05), whereas the percentage of asthmatics was equally distributed between seropositive and seronegative subjects. IgG titers > or = 1:128 were found more frequently in atopic subjects (p = 0.04). After adjusting for any confounding factors, cough and phlegm (but not wheezing) were found significantly associated with C. pneumoniae positivity, both for 1:32 (OR 1.80; 95% CI: 1.01-3.36; p = 0.05) and for 1:128 titers (OR 2.31; 95% CI: 1.20-4.42; p = 0.01). A significant association was also found for atopy, for titers > or = 1:128 (OR 1.73; 95% CI: 1.01-3.20, p = 0.05). Acute infection was not associated with respiratory symptoms or asthma. We conclude that C. pneumoniae infection is associated with cough and phlegm and may have a role in the pathogenesis of chronic respiratory diseases. Moreover, our results indicate a relationship between atopy and C. pneumoniae infection.

Respiratory syncytial virus and chlamydia are not detectable by PCR in ongoing vernal keratoconjunctivitis

Respiratory syncytial virus (RSV) and chlamydial infection may be pathogenetic factors in allergic diseases, perhaps also in ocular allergy. We analyzed the presence of RSV and chlamydial nucleic acids using reverse transcription (RT)-PCR and PCR, respectively, in conjunctival biopsies from patients with vernal keratoconjunctivitis (VKC) in order to determine whether these agents play a role in the maintenance of the disease. All biopsy samples were negative for both RSV (n = 15 for VKC and n = 10 for control subjects) and chlamydia (n = 8 for VKC and n = 7 for control subjects) homologous sequences. A direct association between RSV or chlamydial infection and ongoing inflammation in VKC could, therefore, not be confirmed.

Diagnostic moléculaire en pathologie infectieuse: intérêt d'un diagnostic multiplex dans les pneumopathies atypiques

Among frequent potential respiratory pathogens, Mycoplasma pneumoniæ, Chlamydia pneumoniæ, and Legionella pneumophila are difficult to isolate with usual laboratory techniques (culture, serologic tests). Adapted molecular biology tools are able to amplify a specific genomic target and allow the diagnosis the same day, but with a very time consuming process. The proposed technique allows the diagnosis of the three bacteriaes in a few hours time using a multiplex single-tube polymerase chain reaction.

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

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. 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. 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. 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.

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.

Diagnosis of Chlamydia pneumoniae infection in patients with chronic obstructive pulmonary disease by micro-immunofluorescence and ELISA.

The incidence of Chlamydia pneumoniae infection was determined in patients with chronic obstructive pulmonary diseases (COPD) by prospective serial serology. Chlamydia-specific IgG, IgM and IgA antibodies were detected with a recombinant DNA lipopolysaccharide (LPS) ELISA as well as with a micro-immunofluorescence (MIF) assay with C. pneumoniae elementary bodies. From 271 consecutive COPD patients who visited the outpatient clinic of the department of pulmonary diseases (211 males, 60 females, age range 34-88 years, mean age 66 SD 10 years), blood samples (n = 1058) were taken every 2-7 months; the observation period ranged from 3 to 19 months (mean 15 SD 4). The prevalence of chlamydial IgG was 72% with the MIF and 53% with the rDNA LPS ELISA. More than 90% of the COPD patients had no significant changes in their chlamydia-specific IgG, IgA and IgM titres in either test during the observation period. Seven (3%) patients had MIF results indicating acute C. pneumoniae infection during their surveillance period, of whom five were confirmed by rDNA LPS ELISA. Eleven (4%) additional patients were infected during observation, as determined by rDNA LPS ELISA only. These patients had significantly elevated C. pneumoniae-specific IgG and IgA MIF titres, as compared with the patients without infection. All 18 patients with serological evidence of acute infection during their surveillance period were re-tested in a commercial MIF test that can distinguish between C. pneumoniae, C. trachomatis and C. psittaci LPS-specific antibodies, but no evidence of C. trachomatis or C. psittaci infection was found. The incidence of chlamydial infection was 2.2 and 5.3/100 person-years, when diagnosed by MIF and rDNA LPS ELISA, respectively. It is concluded that the rDNA LPS chlamydia assay may currently be the most sensitive serological tool for diagnosing recent respiratory chlamydia infections and that C. pneumoniae infection occurs frequently in COPD patients.

Respiratory chlamydia: the management of an outbreak

This investigation was undertaken in response to the occurrence of nine cases ofrespiratory chlamydial infection in 8 months within the district of Dudley. All nine cases of respiratory Chamydia were due to Chlamydia psittaci, not Chlamydia pneumoniae. Five cases had avian exposure, but no other aetiological factors were identified. Faecal specimens were obtained from only two of the implicated birds and were negative. Two local aviaries were identified as sources of implicated birds. The two aviaries were themselves linked. Bird faecal specimens were taken from the two implicated aviaries and were both positive for Chlamydia psittaci. Appropriate public health control measures were introduced in these aviaries. A press statement was released to identify and advise, by telephone, those who purchased birds from the aviaries.

Lung infections in children.

Airway infections in children is a considerably broad topic. This discussion focuses on several common nonbacterial causes of lower respiratory tract infection in children, including respiratory syncytial virus, Mycoplasma pneumoniae, and Chlamydia pneumoniae. In addition, the occurrence of two important bacterial causes of lower respiratory illness (Bordetella pertussis and Mycobacterium tuberculosis) is increasing. This review focuses on current information on the prophylaxis, treatment, and diagnosis of these agents. Finally, consideration is given to infections in immunocompromised children: the effects of respiratory syncytial virus infections in immunosuppressed transplant patients, and prevention and diagnosis of opportunistic infections (including Pneumocystis carinii) in children with human immunodeficiency virus.

▾ Clarithro- and ▾ azithromycin – better erythromycins?

Erythromycin is a long established alternative to penicillins in the treatment of bacterial throat infection, in pneumococcal pneumonia and in streptococcal or staphylococcal infection of the skin or soft tissues. It is the first choice in pneumonias due to Mycoplasma pneumoniae, legionella and respiratory chlamydia. Erythromycin generally has to be given four times daily, and unwanted effects, particularly nausea, abdominal pain and vomiting, are common. Low activity against Haemophilus influenzae is a further drawback. Two new macrolide antibiotics, clarithromycin and azithromycin, seem to have possible advantages over erythromycin.

Pneumonia associated with infection with pneumocystis, respiratory syncytial virus, chlamydia, mycoplasma, and cytomegalovirus in children in Papua New Guinea.

Paired serum samples were collected from 94 children with pneumonia admitted to Goroka Hospital, Papua New Guinea. All but three of the children were aged 1-24 months. Only nine children were malnourished, with weight for age less than 70% of the Harvard median (three had weight for age less than 60% of the Harvard median). Pneumocystis carinii antigen was detected in the serum of 23 children. Twenty two children had serological evidence of recent infection with respiratory syncytial virus. Five children were probably infected with Chlamydia trachomatis at the time of the study, and there was less convincing serological evidence of current infection in a further 11 children. Five children showed a fourfold rise in antibody to Mycoplasma pneumoniae. Although only one child showed a fourfold rise in antibody to cytomegalovirus, 86 children had this antibody. No child showed a fourfold rise in antibody to Ureaplasma urealyticum or Legionella pneumophila. P carinii, respiratory syncytial virus, C trachomatis, M pneumoniae, and cytomegalovirus may be important causes of pneumonia in children in developing countries.