Parachlamydia acanthamoebae Detected during a Pneumonia Outbreak in Southeastern Finland, in 2017–2018

Hokynar, Kati; Kurkela, Satu; Nieminen, Tea; Saxén, Harri; Vesterinen, Eero J.; Mannonen, Laura; Pietikäinen, Risto; Puolakkainen, Mirja

doi:10.3390/microorganisms7050141

Cited by 8 publications

(4 citation statements)

References 38 publications

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“…As we pointed out previously [ 23 ], there are increasing doubts whether only these species play a role in human mucosal disease. In recent years, several new types of Chlamydia have been found in human samples from volunteers without disease symptoms [ 35 , 36 ] or patients with respiratory diseases [ 37 , 38 , 39 ]. In addition, Candidatus Renichlamydia lutjani was found in a patient with acute pneumonia, and this infection was recognized by ELISA specific to C. pneumoniae [ 23 ].…”

Section: Discussionmentioning

confidence: 99%

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

Smolejová

Krčmáriková²,

Cihová

et al. 2023

Microorganisms

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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.

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Section: Discussionmentioning

confidence: 99%

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

Smolejová

Krčmáriková²,

Cihová

et al. 2023

Microorganisms

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“…Surprisingly, sequences from three samples did not belong to either of the four assayed species. In recent years, several new types of Chlamydia have been found in human samples from volunteers without disease symptoms [ 63 , 64 ] or patients with respiratory diseases [ 47 , 65 , 66 ]. Sample 1080 contained DNA related to Ca.…”

Section: Discussionmentioning

confidence: 99%

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

2021

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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.

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“…Children may have a higher frequency of infection with C. pneumoniae 9 10. However, recent studies suggest that the prevalence of Chlamydia infection is probably underestimated due to a lack of awareness11–13 or testing limitations 14. In addition, some studies suggest that Chlamydia infection is a risk factor for asthma,15 Alzheimer’s disease16 and cardiovascular disease 17 .…”

Section: Introductionmentioning

confidence: 99%

Prevalence of atypical pathogens in patients with severe pneumonia: a systematic review and meta-analysis

et al. 2023

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ObjectivesWe aimed to summarise the prevalence of atypical pathogens in patients with severe pneumonia to understand the prevalence of severe pneumonia caused by atypical pathogens, improve clinical decision-making and guide antibiotic use.DesignSystematic review and meta-analysis.Data sourcesPubMed, Embase, Web of Science and Cochrane Library were searched through November 2022.Eligibility criteriaEnglish language studies enrolled consecutive cases of patients diagnosed with severe pneumonia, with complete aetiological analysis.Data extraction and synthesisWe conducted literature retrieval on PubMed, Embase, Web of Science and The Cochrane Library to estimate the prevalence ofChlamydia,MycoplasmaandLegionellain patients with severe pneumonia. After double arcsine transformation of the data, a random-effects model was used for meta-analyses to calculate the pooled prevalence of each pathogen. Meta-regression analysis was also used to explore whether the region, different diagnostic method, study population, pneumonia categories or sample size were potential sources of heterogeneity.ResultsWe included 75 eligible studies with 18 379 cases of severe pneumonia. The overall prevalence of atypical pneumonia is 8.1% (95% CI 6.3% to 10.1%) In patients with severe pneumonia, the pooled estimated prevalence ofChlamydia,MycoplasmaandLegionellawas 1.8% (95% CI 1.0% to 2.9%), 2.8% (95% CI 1.7% to 4.3%) and 4.0% (95% CI 2.8% to 5.3%), respectively. We noted significant heterogeneity in all pooled assessments. Meta-regression showed that the pneumonia category potentially influenced the prevalence rate ofChlamydia. The mean age and the diagnostic method of pathogens were likely moderators for the prevalence ofMycoplasmaandLegionella, and contribute to the heterogeneity of their prevalence.ConclusionsIn severe pneumonia, atypical pathogens are notable causes, especiallyLegionella. The diagnostic method, regional difference, sample size and other factors contribute to the heterogeneity of prevalence. The estimated prevalence and relative heterogeneity factors can help with microbiological screening, clinical treatment and future research planning.PROSPERO registration numberCRD42022373950.

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Parachlamydia acanthamoebae Detected during a Pneumonia Outbreak in Southeastern Finland, in 2017–2018

Cited by 8 publications

References 38 publications

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

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

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

Prevalence of atypical pathogens in patients with severe pneumonia: a systematic review and meta-analysis

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