Chlamydophila pneumoniae diagnostics: importance of methodology in relation to timing of sampling

Chlamydia psittaci Screening of Animal Workers from Argentina Exposed to Carrier Birds

Different syndromes are involved in human psittacosis (flu-like syndrome, atypical pneumonia up to lacrimal gland lymphoma). Diagnostic methods include serology, culture, and PCR. The rate of Chlamydia psittaci (Cp) positive tests among exposed workers is still unknown. Our study aimed to assess the rate of positive tests among workers who have contact with carrier birds in natural reserves from Buenos Aires, Argentina. Secondary aims were to analyze risk factors linked to these outcomes and the occurrence of signs that suggest psittacosis. Nasopharyngeal swabs and serum pairs were collected from employees who had interacted with confirmed carrier birds. Those with detectable DNA of Cp and/or anti-Chlamydia spp. antibody baseline titer ≥ 160 mUI/ml, or at least quadruplicating, were considered positive. Activities performed with or near birds, personal protective equipment use, and previous chronic conditions were assessed. Possible Cp-related pathologies were evaluated during follow-up. A total of 63 exposed workers (71.4% men) with a median age of 35.7 years (IQR 26-39) were evaluated to detect 28.6% positives. Respiratory chronic conditions were the unique factor associated with positive tests (OR 5.2 [1.5-18.5] p < .05). Surprisingly, about a third of the workers resulted positive and all responded to medical treatment, none developing an acute atypical pneumonia syndrome associated with classical presentation of psittacosis. Active testing for early diagnosis and proper treatment in zoological workers exposed to carrier or potentially carrier birds is strongly suggested as part of zoonotic diseases preventive measures.

Are ELISA and PCR Discrepancies in the Identification of Chlamydia pneumoniae Caused by the Presence of "Chlamydia-Related Bacteria"?

Chlamydia are Gram-negative, intracellular pathogens colonizing the epithelial mucosa. They cause primarily atypical pneumonia and have recently been associated with chronic diseases. Diagnostics rely almost exclusively on serological methods; PCR tests are used rarely because in patients with positive ELISA, it is nearly impossible to identify chlamydial DNA. To understand this issue, we elaborated a reliable and sensitive nested PCR method (panNPCR) for identifying all Chlamydiales species, not only in sputa, but also in clotted blood. Sequencing of the PCR product revealed that 41% of positive sputa samples and 66% of positive blood samples were not infected by Chlamydia but with "Chlamydia-related bacteria" such as Rhabdochlamydia sp., Parachlamydia sp., Protochlamydia sp., Neochlamydia sp., Mesochlamydia elodeae and lacustris, Piscichlamydia salmonis, and Estrella lausannensis. Consequently, we propose that there might be more than four human pathogenic Chlamydia species. We did not find any clear correlation between increased levels of antibodies and the presence of their DNA. Chlamydialles DNA was found in sputa samples from individuals positive for IgG or IgA but not in blood samples. Thus, elevated IgG and IgA levels are not reliable markers of chronic infection, and the presence of persistent forms should be proved by panNPCR. Apparently, the differences between ELISA and DNA amplification results have three main methodological reasons. The first one is the threshold occurrence of chlamydial genetic material in sputum and blood. The second one is the fact that a significant part of the samples can have DNA with sequences different from those of other species of the order Chlamydiales. The third one is the high background characteristic for ELISA, the absence of paired sera, and the vague interpretation of the gray zone.

Mycoplasma pneumoniae and Chlamydia pneumoniae Coinfection with Acute Respiratory Distress Syndrome: A Case Report

Community-acquired pneumonia caused by Mycoplasma pneumoniae or Chlamydia pneumoniae is usually mild. Mycoplasma pneumoniae-related and C. pneumoniae-related acute respiratory distress syndromes (ARDSs) are rare. Moreover, to our knowledge, there are no published reports on ARDS caused by M. pneumoniae and C. pneumoniae coinfection. Here, we report a case of an immunocompetent young woman who was co-infected with M. pneumoniae and C. pneumoniae and was started on treatment with piperacillin and clarithromycin. Two days later, she developed ARDS. She recovered rapidly following a change of antibiotic treatment to levofloxacin and was discharged on day 12. We conducted exome sequencing followed by alternative filtering to search for candidate ARDS-related genes. We identified an intronic variant of unknown significance within leucine-rich repeat-containing 16A (LRRC16A), a gene previously identified as a significant locus for platelet count with a possible role in ARDS. This is a rare case of ARDS in a young adult caused by M. pneumoniae and C. pneumoniae coinfection. This case suggests that ARDS in young adults may be correlated with variants in LRRC16A. This requires confirmation by further case reports.

Chlamydia pneumoniae-associated pleuropericarditis: a case report and systematic review of the literature

BACKGROUND

Chlamydia pneumoniae is a common cause of atypical community acquired pneumonia (CAP). The diagnostic approach of chlamydial infections remains a challenge. Diagnosis of delayed chlamydial-associated complications, involving complex autoimmune pathophysiological mechanisms, is still more challenging. C. pneumoniae-related cardiac complications have been rarely reported, including cases of endocarditis, myocarditis and pericarditis.

CASE PRESENTATION

A 40-year old female was hospitalized for pleuropericarditis following lower respiratory tract infection. The patient had been hospitalized for CAP (fever, dyspnea, chest X-ray positive for consolidation on the left upper lobe) 5 weeks ago and had received ceftriaxone and moxifloxacin. Four weeks after her discharge, the patient presented with fever, shortness of breath and pleuritic chest pain and was readmitted because of pericardial and bilateral pleural effusions (mainly left). The patient did not improve on antibiotics and sequential introduction of colchicine and methylprednisolone was performed. The patient presented impressive clinical and laboratory response. Several laboratory and clinical assessments failed to demonstrate any etiological factor for serositis. Chlamydial IgM and IgG antibodies were positive and serial measurements showed increasing kinetics for IgG. Gold standard polymerase chain reaction of respiratory tract samples was not feasible but possibly would not have provided any additional information since CAP occurred 5 weeks ago. The patient was discharged under colchicine and tapered methylprednisolone course. During regular clinic visits, she remained in good clinical condition without pericardial and pleural effusions relapse.

CONCLUSIONS

C. pneumoniae should be considered as possible pathogen in case of pleuritis and/or pericarditis during or after a lower respiratory tract infection. In a systematic review of the literature only five cases of C. pneumoniae associated pericarditis were identified. Exact mechanisms of cardiovascular damage have not yet been defined, yet autoimmune pathways might be implicated.

Reliable and Sensitive Nested PCR for the Detection of Chlamydia in Sputum

Chlamydia are Gram-negative, intracellular pathogens colonizing epithelial mucosa. They cause primarily atypical pneumonia and have recently been associated with chronic diseases. Diagnostics relies almost exclusively on serological methods; PCR tests are used rarely because in patients with positive ELISA, it is nearly impossible to identify chlamydial DNA. This paradox is associated with DNA degradation in sputum samples, low abundance, and low sensitivity of PCR systems. In a newly designed and validated “nested” PCR (NPCR) assay, it was possible to amplify DNA of Chlamydia known to infect humans in 31% samples. The reliability of the assay was confirmed by DNA sequencing, and all PCR products belonged exclusively to the Chlamydiales, mainly recognized as Chlamydia pneumoniae. Three samples were related to Ca. Rhabdochlamydia porcellionis and Ca. Renichlamydia lutjani, which infect arthropods. In one case, samples were taken from sick individual, indicating the potential as a human pathogen.

Acute haemorrhagic pericarditis: an unusual presentation of Chlamydophila pneumoniae pneumonia infection

, a common cause of respiratory tract infections, rarely leads to serious conditions. A 13-year-old boy with serologically confirmed C. pneumoniae infection presented with pneumonia complicated by pericardial and bilateral pleural effusions. He had a large haemorrhagic pericardial effusion from which 1000 ml of fluid was aspirated over 10 days and a right haemorrhagic pleural effusion which required a chest drain and the removal of 700 ml over 5 days. The addition of clarithromycin to ceftriaxone appeared to enhance recovery. As far as we are aware, this is the first report in the English literature of massive haemorrhagic pericardial and pleural effusions in children owing to C. pneumoniae infection.

Discovery of Human-Specific Immunodominant Chlamydia trachomatis B Cell Epitopes

Current serological assays for species-specific detection of anti-Chlamydia species antibodies suffer from well-known shortcomings in specificity and ease of use. Due to the high prevalences of both anti-C. trachomatis and anti-C. pneumoniae antibodies in human populations, species-specific serology is unreliable. Therefore, novel specific and simple assays for chlamydial serology are urgently needed. Conventional antigens are problematic due to extensive cross-reactivity within Chlamydia spp. Using accurate B cell epitope prediction and a robust peptide ELISA methodology developed in our laboratory, we identified immunodominant C. trachomatis B cell epitopes by screening performed with sera from C. trachomatis-infected women. We discovered 38 novel human host-dependent antigens from 20 immunodominant C. trachomatis proteins, in addition to confirming 10 host-independent mouse serum peptide antigens that had been identified previously. This extended set of highly specific C. trachomatis peptide antigens can be used in simple ELISA or multiplexed microarray formats and will provide high specificity and sensitivity to human C. trachomatis serodiagnosis.

Chlamydia species-specific serology is compromised by cross-reactivity of the gold standard microimmunofluorescence (MIF) or commercial enzyme-linked immunosorbent assays (ELISAs). This study was conducted to discover novel C. trachomatis-specific peptide antigens that were recognized only by the antibody response of the natural human host. We evaluated a library of 271 peptide antigens from immunodominant C. trachomatis proteins by reactivity with 125 C. trachomatis antibody-positive sera from women with PCR-confirmed C. trachomatis infection and 17 C. trachomatis antibody-negative sera from low-risk women never diagnosed with C. trachomatis infection. These C. trachomatis peptide antigens had been predicted in silico to contain B cell epitopes but had been nonreactive with mouse hyperimmune sera against C. trachomatis. We discovered 38 novel human host-dependent antigens from 20 immunodominant C. trachomatis proteins (PmpD, IncE, IncG, CT529, CT618, CT442, TarP, CT143, CT813, CT795, CT223, PmpC, CT875, CT579, LcrE, IncA, CT226, CT694, Hsp60, and pGP3). Using these human sera, we also confirmed 10 C. trachomatis B cell epitopes from 6 immunodominant C. trachomatis proteins (OmpA, PmpD, IncE, IncG, CT529, and CT618) as host species-independent epitopes that had been previously identified by their reactivity with mouse hyperimmune sera against C. trachomatis. ELISA reactivities against these peptides correlated strongly with the C. trachomatis microimmunofluorescence (MIF) text results (Pearson’s correlation coefficient [R] = 0.80; P < 10⁻⁶). These C. trachomatis peptide antigens do not cross-react with antibodies against other Chlamydia species and are therefore suitable for species-specific detection of antibodies against C. trachomatis. This study identified an extended set of peptide antigens for simple C. trachomatis-specific ELISA serology.

IMPORTANCE Current serological assays for species-specific detection of anti-Chlamydia species antibodies suffer from well-known shortcomings in specificity and ease of use. Due to the high prevalences of both anti-C. trachomatis and anti-C. pneumoniae antibodies in human populations, species-specific serology is unreliable. Therefore, novel specific and simple assays for chlamydial serology are urgently needed. Conventional antigens are problematic due to extensive cross-reactivity within Chlamydia spp. Using accurate B cell epitope prediction and a robust peptide ELISA methodology developed in our laboratory, we identified immunodominant C. trachomatis B cell epitopes by screening performed with sera from C. trachomatis-infected women. We discovered 38 novel human host-dependent antigens from 20 immunodominant C. trachomatis proteins, in addition to confirming 10 host-independent mouse serum peptide antigens that had been identified previously. This extended set of highly specific C. trachomatis peptide antigens can be used in simple ELISA or multiplexed microarray formats and will provide high specificity and sensitivity to human C. trachomatis serodiagnosis.

Mucositis Secondary to Chlamydia pneumoniae Infection: Expanding the Mycoplasma pneumoniae-Induced Rash and Mucositis Concept

The term Mycoplasma pneumoniae-induced rash and mucositis (MIRM) was recently proposed to identify the mucocutaneous condition secondary to M. pneumoniae infection that had historically been regarded among the more confusing pathologies of erythema multiforme and Stevens-Johnson syndrome. Based on a number of previous reports, these syndromes require differentiation since they have different prognoses and specific treatment requirements. We report a case of oral and genital erosions that strongly resembled MIRM without rash but were found to be secondary to a Chlamydia pneumoniae infection. After a thorough review of the literature on this subject, we propose that C. pneumoniae should also be considered a potential causative agent of MIRM and that this term should be amended to include C. pneumoniae infection.

Antibody responses of Chlamydophila pneumoniae pneumonia: Why is the diagnosis of C. pneumoniae pneumonia difficult?

The ELNAS Plate Chlamydophila pneumoniae commercial test kit for the detection of anti-C. pneumoniae-specific immunoglobulin M (IgM), IgA and IgG antibodies has become available in Japan recently. To determine the optimum serum collection point for the ELNAS plate in the diagnosis of C. pneumoniae pneumonia, we analyzed the kinetics of the antibody response in patients with laboratory-confirmed C. pneumoniae pneumonia. We enrolled five C. pneumoniae pneumonia cases and collected sera from patients for several months. The kinetics of the IgM and IgG antibody responses were similar among the five patients. Significant increases in IgM and IgG antibody titer between paired sera were observed in all patients. IgM antibodies appeared approximately 2-3 weeks after the onset of illness, reached a peak after 4-5 weeks, and were generally undetectable after 3-5 months. IgG antibodies developed slowly for the first 30 days and reached a plateau approximately 3-4 months after the onset of illness. The kinetics of IgA antibody responses were different among the five patients, and significant increases in IgA antibody titer between paired sera were observed in only two patients. Although the sample size was small, the best serum collection time seemed to be approximately 3-6 weeks after onset of illness when using a single serum sample for the detection of IgM antibodies. Paired sera samples should be obtained at least 4 weeks apart. IgA antibody analysis using ELNAS may not be a useful marker for acute C. pneumoniae pneumonia.

Chlamydia pneumoniae infection and cerebrovascular disease: a systematic review and meta-analysis

Background

A wealth of published studies have been published on association between Chlamydia pneumoniae (C.pneumoniae) infection and cerebrovascular (CV) disease, but the results were inconsistent. This meta-analysis provides a systematic review of the available evidence from all serological and pathological studies of CV disease and C.pneumoniae.

Methods

A comprehensive research was conducted of MEDLINE, EMBASE, CNKI, WanFang technological periodical database and reference lists of articles to identify eligible case-control and cohort studies. Odds radio (OR) was calculated for each study outcome. Random effect model was used as pooling method and publication bias was estimated for the results.

Results

Fifty-two published studies that met criteria were selected. In case control studies, an association between C.pneumoniae infection and CV disease was revealed by serum specific IgG (OR, 1.61; 95% CI: 1.34 to 1.94), serum IgA (OR, 2.33; 95% CI: 1.76 to 3.08) and PCR technique of C.pneumoniae in peripheral blood cells (OR, 1.90; 95% CI: 1.17 to 3.07). No significant association was found in serum anti-C.pneumonae IgM seropositivity or in-situ-detection of C.pneumoniae in arterial biopsies with CV disease. Subgroup analysis by available studies suggested that C.pneumoniae may paly a role in atherosclerotic stroke, but be less significant in stroke of cardioembolism or other etiologies.

Conclusion

Association between C.pneumoniae infection and CV disease depends on the analytical method adopted, which seems stronger with stroke due to large artery atherosclerosis. Establishing a causal relationship between C.peumoniae infection and CV disease will require more prospective studies with combination of techniques and stratified by etiological subtypes.

[Microbiological diagnosis of infections due to Chlamydia spp. and related species]

Until recently the number of completed genomes belonging to Chlamydia trachomatis was very low, despite its importance in Public Health. Now, there are currently sixty-six completed genomes of C.trachomatis sequenced in different parts of the world. This genomic revolution has helped in understanding its biology, as well as improved the sensitivity and specificity in the diagnosis, and the development of epidemiological tools, not only for in C.trachomatis, but also for related species such as C.pneumoniae and C.psittaci. The diagnosis based on cell culture, serology and microimmunofluorescence is gradually being replaced by molecular techniques based on PCR or real-time PCR. This is because these molecular tests do not have cross-reactions problems and the procedures are easily standardised between laboratories. Moreover, molecular epidemiology tools described recently, such as Multi-Locus Sequence Typing (MLST) and Variable Number Tandem Repeat (VNTR), have increased our knowledge on local and global epidemiology. This article focuses on the impact of the genomics advances achieved over the last few years as applied to the diagnosis, epidemiology and biology of the family Chlamydiaceae family and related species.

Chronic Pharyngitis: Role of Atypical Organisms

Background

Bacteria including Chlamydophila pneumoniae, Mycoplasma pneumoniae, and anaerobic bacteria such as Fusobacterium necrophorum have been implicated as etiological agents of chronic pharyngitis in Western literature. Because there are no data regarding this from India, the authors undertook this study.

Study Design

Prospective case-control study.

Setting

Tertiary-level medical college and hospital.

Method

In total, 343 consecutive adults with persistent throat pain and/or irritation (duration ≥3 months) were screened for known causes of pharyngitis by a thorough clinical and endoscopic examination. In 71 patients, the evaluation performed was unable to determine any cause, and these were considered cases. An enzyme-linked immunosorbent assay test to detect IgA and IgG antibodies to C pneumoniae and M pneumoniae was performed on 66 of these cases and 62 controls. The posterior pharyngeal swabs taken from both the cases and controls were subjected to aerobic and anaerobic culture.

Results

Individuals with chronic pharyngitis had a 3.43 times odds of being seropositive for C pneumoniae as compared with controls ( P = .001; odds ratio = 3.43). Aerobic organisms and M pneumoniae did not seem to be significant etiological agents for chronic pharyngitis. On the contrary, isolation of Fusobacterium spp was found to be significantly more in controls as compared with cases.

Conclusion

This study suggests an association between IgA antibodies to C pneumoniae and chronic pharyngitis. Further studies using more specific tests combined with long-term follow-up are needed to confirm these findings.

Guidelines for the management of adult lower respiratory tract infections--summary

This document is an update of Guidelines published in 2005 and now includes scientific publications through to May 2010. It provides evidence-based recommendations for the most common management questions occurring in routine clinical practice in the management of adult patients with LRTI. Topics include management outside hospital, management inside hospital (including community-acquired pneumonia (CAP), acute exacerbations of COPD (AECOPD), acute exacerbations of bronchiectasis) and prevention. The target audience for the Guideline is thus all those whose routine practice includes the management of adult LRTI.

Guidelines for the management of adult lower respiratory tract infections--full version

This document is an update of Guidelines published in 2005 and now includes scientific publications through to May 2010. It provides evidence-based recommendations for the most common management questions occurring in routine clinical practice in the management of adult patients with LRTI. Topics include management outside hospital, management inside hospital (including community-acquired pneumonia (CAP), acute exacerbations of COPD (AECOPD), acute exacerbations of bronchiectasis) and prevention. Background sections and graded evidence tables are also included. The target audience for the Guideline is thus all those whose routine practice includes the management of adult LRTI.

Chlamydia pneumoniae infection-related hemophagocytic lymphohistiocytosis and acute encephalitis and poliomyelitis-like flaccid paralysis

A 3-year-old male presented with Chlamydia pneumoniae infection-related hemophagocytic lymphohistiocytosis (HLH). The patient developed an episode of HLH with severe skin eruption following C. pneumoniae pneumonia. Symptoms responded to steroid/cyclosporine A therapy, but the patient slowly lost consciousness and developed systemic flaccid paralysis. He was diagnosed with encephalitis/myelitis by brain and spinal MRI. Neurological symptoms and signs gradually resolved. We thought that the immune response to C. pneumoniae infection triggered the development of HLH, associated with unusual neurological complications. This report describes a novel case of C. pneumoniae-associated HLH and with poliomyelitis like flaccid paralysis.

Elevated serum immunoglobulin G titers against Chlamydia pneumoniae in primary open-angle glaucoma patients without systemic disease

PURPOSE

To determine if Chlamydia pneumoniae infection is associated with primary open-angle glaucoma (POAG).

PATIENTS AND METHODS

Consecutive patients with newly diagnosed primary POAG attending the Glaucoma clinic of Keio University Hospital between June 2007 and January 2008 were considered for inclusion in this prospective case-control study. Forty consecutive POAG patients and 41 normal healthy individuals as a control population met the inclusion criteria. The exclusion criteria for both groups were; taking steroids or immunosuppressive agents, smoking, and history of any acute or chronic systemic disease including stroke, heart attack, diabetes mellitus, hypertension, asthma, and autoimmune diseases. The serum was analyzed for C. pneumoniae and C. trachomatis immunoglobulin G antibody titers by enzyme-linked immunosorbent assay. Seroactivity to each antigen between case and control groups was evaluated by Mann-Whitney U test.

RESULTS

The age, male/female ratio, and intraocular pressure of the cases and control groups were not significantly different. Immunoglobulin G titers for C. pneuemoniae was significantly higher in patients with POAG than in controls (P=0.009). The titers to C. trachomatis were not significantly different between the 2 groups (P=0.99).

CONCLUSION

The results suggest that higher C. pneumoniae titers are associated with POAG. If confirmed, this may indicate either a common factor that causes susceptibilities to both glaucoma and C. pneumoniae infection or that C. pneumoniae may be a causal factor for developing POAG.

Chlamydophila pneumoniae

Chlamydophila pneumoniae is estimated to cause about 10% of community-acquired pneumonia (CAP) cases and 5% of bronchitis cases, although most patients with C pneumoniae infection are asymptomatic, and the course of respiratory illness is relatively mild. The incubation period of C pneumoniae infection is around 21 days, and such symptoms as cough and malaise show a gradual onset, yet may persist for several weeks or months despite appropriate antibiotic therapy. Diagnosis by nasopharyngeal specimen culture, serum antibody titers, or molecular techniques is usually delayed with respect to the onset of symptoms, antibiotic treatment, or disease resolution and there is no accurate, standardized, commercial US Food and Drug Administration-cleared diagnostic method available. Erythromycin, tetracycline, and doxycycline are used as first-line therapy, although some investigators report no clinical or survival benefits from treating CAP caused by atypical pathogens. Meanwhile, adequate prospective studies have met with ethical and logistic barriers. Despite these limitations, North American guidelines recommend the antimicrobial treatment of patients with acute C pneumoniae respiratory infection.