Identification and comparison of Chlamydia psittaci, Legionella and Mycoplasma pneumonia infection

Abstract

Introduction Conventional etiological detection and pathogenic antibody methods make it challenging to identify the atypical pathogens among the community‐acquired pneumonia (CAP). Metagenomic next‐generation sequencing (mNGS) could rapidly detect all potentially infectious diseases and identifies novel or potential pathogens. Methods Eighteen patients diagnosed with atypical CAP were enrolled in this retrospective study, including nine Chlamydia psittaci pneumonia (C. p), four Legionella pneumonia (L. p) and five Mycoplasma pneumonia (M. p). We simultaneously tested bronchoalveolar lavage fluid (BALF) samples for conventional microbiological methods and mNGS, and blood specimens were analysed. We also collected and compared baseline and clinical characteristics and treatment responses. Results Patients with C. p and L. p had similar symptoms, including fever, cough, headache, dyspnoea, asthenia, shivering and headache, compared with M. p, whose symptoms were slight. C. p and L. p usually showed multiple lobar distributions with pleural effusion. Serologic testing indicated that L. p had higher levels of white blood cells (WBCs), neutrophils, C‐reactive protein (CRP), procalcitonin (PCT), alanine aminotransferase (ALT), lactate dehydrogenase (LDH) and creatinine compared with M. p and L. p (p < 0.05). However, patients with C. p had lower levels of albumin (p < 0.05), and M. p had a minimum risk of cardiac volume loads (p < 0.05). CD4/CD8 ratio, lymphocytes, aspartate aminotransferase (AST), creatine kinase (CK), cell counting of BALF and coagulation had no difference (p < 0.05). Pathogenic IgM assay showed that 4/5 cases were positive for M. p and no positive detection for C. p and L. p infection. We timely adjusted the antibiotics according to the final mNGS results. Eventually, 16/18 patients recovered fully. Conditions of L. p patients were worse than those of C. p patients, and those of M. p patients were the least. Conclusion Early application of mNGS detection increased the atypical pathogenic identification, improved the prognosis and made up for the deficiency of conventional detection methods.

Multiple pulmonary cavities in an immunocompetent patient: a case report and literature review

“…However, they have limitations such as time-consuming culture results, sensitivity issues, and potential false positives ( 3 , 22 – 24 ). In contrast, mNGS has proven to be effective in identifying challenging-to-culture pathogens like Legionella ( 25 ). It utilizes nucleic acid detection and molecular techniques, which offer enhanced sensitivity, specificity, and rapid pathogen detection throughput ( 26 ).…”

Case Report: Metagenomic next-generation sequencing applied in diagnosing psittacosis caused by Chlamydia psittaci infection

“…In the family’s community in the urban area of Shanghai, east China, nothing is unusual in the environment, ecology, urbanization, and pet habits. A recent report reveals that C. psittaci pneumonia was identified in 9 patients from November 2018 to December 2021 at Huashan Hospital in Shanghai ( Zhu et al., 2023 ), suggesting a relatively low prevalence of psittacosis in this region. From the perspective of the chronological order of symptoms appearance, the initial case (case 1) was more likely infected by the contagious parrot, with a reasonable incubation period of 11 days (from 24 October 2022 to 3 November 2022).…”