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.Methods/Principal FindingsWe 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/SignificanceThe 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.
Highlights
Pneumocystis jirovecii pneumonia (PcP) was the leading cause of morbidity and mortality in HIV+ patients early in the HIV/AIDS epidemic [1,2,3]
We examined the serologic responses to P. jirovecii infection in early childhood; geographic differences in seroreactivity to major surface glycoprotein recombinant fragment C1 (MsgC1); and the specific factors independently related to high antibody levels to MsgC1 in longterm cohort study [28,29,30,31]
All cases (100%) were treated for PcP while undergoing diagnostic evaluation compared to 66.7% of the controls (p,0.01), and the cases were more likely to be treated with trimethoprimsulfamethoxazole (TMP-SMX) compared to controls (74.6% vs. 55.6%) (p,0.01)
Summary
Pneumocystis jirovecii pneumonia (PcP) was the leading cause of morbidity and mortality in HIV+ patients early in the HIV/AIDS epidemic [1,2,3]. PcP remains an important clinical problem in HIV+ and other immunocompromised patients with mortality rates ranging from 10–60% depending on the underlying disease [2,3]. HIV+ patients with a suggestive clinical picture of PcP are treated empirically for PcP [5]. In such cases, non-invasive and non-specific methods such as chest radiographs, serum lactic dehydrogenase (LDH), or serum bglucan levels may be used to help support the diagnosis [6,7,8,9]. Pneumocystis jirovecii remains an important cause of fatal pneumonia (Pneumocystis pneumonia or PcP) in HIV+ patients and other immunocompromised hosts. A clinically useful serologic test for P. jirovecii infection has never been developed
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