title: Serum antibody levels to the Pneumocystis jirovecii major surface glycoprotein in the diagnosis of P. jirovecii pneumonia in HIV+ patients.
abstract: BACKGROUND
  Pneumocystis jirovecii remains an important cause of fatal pneumonia (Pneumocystis pneumonia or PcP) in HIV+ patients and other immunocompromised hosts. Despite many previous attempts, a clinically useful serologic test for P. jirovecii infection has never been developed.
  
  
  RESULTS
  We analyzed serum antibody responses to the P. jirovecii major surface glycoprotein recombinant fragment C1 (MsgC1) in 110 HIV+ patients with active PcP (cases) and 63 HIV+ patients with pneumonia due to other causes (controls) by an enzyme-linked immunosorbent assay (ELISA). The cases had significantly higher IgG and IgM antibody levels to MsgC1 than the controls at hospital admission (week 0) and intervals up to at least 1 month thereafter. The sensitivity, specificity and positive predictive value (PPV) of IgG antibody levels increased from 57.2%, 61.7% and 71.5% at week 0 to 63.4%, 100%, and 100%, respectively, at weeks 3-4. The sensitivity, specificity and PPV of IgM antibody levels rose from 59.7%, 61.3%, and 79.3% at week 0 to 74.6%, 73.7%, and 89.8%, respectively, at weeks 3-4. Multivariate analysis revealed that a diagnosis of PcP was the only independent predictor of high IgG and IgM antibody levels to MsgC1. A high LDH level, a nonspecific marker of lung damage, was an independent predictor of low IgG antibody levels to MsgC1.
  
  
  CONCLUSIONS
  The results suggest that the ELISA shows promise as an aid to the diagnosis of PCP in situations where diagnostic procedures cannot be performed. Further studies in other patient populations are needed to better define the usefulness of this serologic test.
authors.affiliation: Veterans Affairs Medical Center, Cincinnati, Ohio, United States of America.
authors.forename: Kpandja
authors.initials: K
authors.lastname: Djawe
authors.forename: Laurence
authors.initials: L
authors.lastname: Huang
authors.forename: Kieran R
authors.initials: KR
authors.lastname: Daly
authors.forename: Linda
authors.initials: L
authors.lastname: Levin
authors.forename: Judy
authors.initials: J
authors.lastname: Koch
authors.forename: Alexandra
authors.initials: A
authors.lastname: Schwartzman
authors.forename: Serena
authors.initials: S
authors.lastname: Fong
authors.forename: Brenna
authors.initials: B
authors.lastname: Roth
authors.forename: Anuradha
authors.initials: A
authors.lastname: Subramanian
authors.forename: Katherine
authors.initials: K
authors.lastname: Grieco
authors.forename: Leah
authors.initials: L
authors.lastname: Jarlsberg
authors.forename: Peter D
authors.initials: PD
authors.lastname: Walzer
mesh_terms: D001992:Bronchoalveolar Lavage Fluid; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D015658:HIV Infections / Q000150:complications* / Q000382:microbiology* / Q000821:virology; D006679:HIV Seropositivity; D006801:Humans; D007074:Immunoglobulin G / Q000737:chemistry; D007075:Immunoglobulin M / Q000737:chemistry; D008297:Male; D008562:Membrane Glycoproteins / Q000737:chemistry*; D015999:Multivariate Analysis; D045363:Pneumocystis carinii / Q000378:metabolism*; D011020:Pneumonia, Pneumocystis / Q000175:diagnosis* / Q000382:microbiology*; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity
chemical_list: D007074:Immunoglobulin G; D007075:Immunoglobulin M; D008562:Membrane Glycoproteins