title: High seroprevalence of Mycoplasma pneumoniae IgM in acute Q fever by enzyme-linked immunosorbent assay (ELISA).
abstract: Q fever is serologically cross-reactive with other intracellular microorganisms. However, studies of the serological status of Mycoplasma pneumoniae and Chlamydophila pneumoniae during Q fever are rare. We conducted a retrospective serological study of M. pneumoniae and C. pneumoniae by enzyme-linked immunosorbent assay (ELISA), a method widely used in clinical practice, in 102 cases of acute Q fever, 39 cases of scrub typhus, and 14 cases of murine typhus. The seropositive (57.8%, 7.7%, and 0%, p<0.001) and seroconversion rates (50.6%, 8.8%, and 0%, p<0.001) of M. pneumoniae IgM, but not M. pneumoniae IgG and C. pneumoniae IgG/IgM, in acute Q fever were significantly higher than in scrub typhus and murine typhus. Another ELISA kit also revealed a high seropositivity (49.5%) and seroconversion rate (33.3%) of M. pneumoniae IgM in acute Q fever. The temporal and age distributions of patients with positive M. pneumoniae IgM were not typical of M. pneumoniae pneumonia. Comparing acute Q fever patients who were positive for M. pneumoniae IgM (59 cases) with those who were negative (43 cases), the demographic characteristics and underlying diseases were not different. In addition, the clinical manifestations associated with atypical pneumonia, including headache (71.2% vs. 81.4%, p=0.255), sore throat (8.5% vs. 16.3%, p=0.351), cough (35.6% vs. 23.3%, p=0.199), and chest x-ray suggesting pneumonia (19.3% vs. 9.5%, p=0.258), were unchanged between the two groups. Clinicians should be aware of the high seroprevalence of M. pneumoniae IgM in acute Q fever, particularly with ELISA kits, which can lead to misdiagnosis, overestimations of the prevalence of M. pneumoniae pneumonia, and underestimations of the true prevalence of Q fever pneumonia.
authors.affiliation: Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung City, Taiwan ; Division of Infectious Diseases, Department of Internal Medicine, E-Da Hospital/I-Shou University, Kaohsiung City, Taiwan ; Division of Infection Control Laboratory, E-Da Hospital/I-Shou University, Kaohsiung City, Taiwan.
authors.forename: Chung-Hsu
authors.initials: CH
authors.lastname: Lai
authors.forename: Lin-Li
authors.initials: LL
authors.lastname: Chang
authors.forename: Jiun-Nong
authors.initials: JN
authors.lastname: Lin
authors.forename: Wei-Fang
authors.initials: WF
authors.lastname: Chen
authors.forename: Li-Li
authors.initials: LL
authors.lastname: Kuo
authors.forename: Hsi-Hsun
authors.initials: HH
authors.lastname: Lin
authors.forename: Yen-Hsu
authors.initials: YH
authors.lastname: Chen
mesh_terms: D000818:Animals; D061387:Chlamydial Pneumonia / Q000276:immunology / Q000382:microbiology; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D007074:Immunoglobulin G / Q000378:metabolism; D007075:Immunoglobulin M / Q000378:metabolism*; D051379:Mice; D009177:Mycoplasma pneumoniae / Q000276:immunology* / Q000472:pathogenicity*; D012285:Orientia tsutsugamushi / Q000472:pathogenicity; D011778:Q Fever / Q000276:immunology* / Q000382:microbiology; D012612:Scrub Typhus / Q000276:immunology / Q000382:microbiology; D014438:Typhus, Epidemic Louse-Borne / Q000276:immunology / Q000378:metabolism
chemical_list: D007074:Immunoglobulin G; D007075:Immunoglobulin M