Dissident AIDS Database

EpidemiologyStatisticsAIDSPCP overdiagnosis
 Papadopulos-Eleopulos Eleni , Turner Valendar F, Hedland-Thomas Bruce, Causer David, Papadimitriou John M.
  "Before the AIDS era, and even in the early 1980's, the visualisation of the causative organism P. carinii in Gomori-methenamine salver (GMS) stained preparation of lung tissue obtained by open lung biopsy was considered the only method suitable for a definite diagnosis of PCP. Even with this method considerable expertise is necessary to differentiate P. carinii from other GMS positive entities, particularly yeast" (Gill, C.P. & Cartwright, V.J. AIDS Clincal Care 6, 79-81, 1994). In the AIDS era, the method used to diagnose PCP became less and less specific. Instead of open lung biopsy, diagnosis began to be obtained by fibreoptic bronchoscopy, a much "less dependable" procedure, or bronchoalveolar lavage (BAL). However, "one might expect to find P. carinii in the fluid from bronchoalveolar lavage of about 40% of patients with AIDS who present with symptomatic pneumonia caused by other organisms" (Hughes, W.T. NEJM 317, 1021-1023, 1987). Despite the very high level of false positive results obtained with BAL, this procedure is not only used to definitely diagnose PCP but, more recently, as a gold standard for other, even less specific procedures used for the "definite" diagnosis of PCP, such as testing specimens from sputum induction using GMS (Bustamante, E.A. & Levy, H. Chest 105, 816-822, 1994). In turn this procedure is used as a gold standard for the "definite" diagnosis of PCP by testing sputum specimens with the use of "monoclonal antibodies". Instead of GMS, although it is accepted that in sputum specimens GMS "will stain not only P. carinii but also host and microbial cells and amorphous debris, which make up a large part of the sputum sample; even in experienced hands, distinguishing P. carinii from this background can be difficult" (Kovacs, J.A., et al. The New England Journal of Medicine 318, 589-593, 1988). Another method presently used for the "definite" diagnosis of PCP is the polymerase chain reaction. However, the authors themselves admit that this method, when compared to detection of P. carinii in BAL or sputum specimens, as gold standard, this procedure is less specific and "most falsely positive samples were from patients treated with immunosuppressive drugs or from HIV- positive patients with CD4 counts below 0.2 x 109/" (Lipschik, G.Y., et al. The Lancet 340, 203-206, 1992). Nonetheless, on the basis of these tests, individuals from the AIDS risk groups, including haemophiliacs are diagnosed as having PCP and are treated accordingly. Some studies recommend the use of "empiric therapy for PCP, based purely on" clinical findings. But, "The propensity of patients with PCP to present with atypical clinical finding, the ability of both infectious and non-infectious diseases to produce a clinical picture compatible with PCP, and the toxicity of anti-pneumocystis treatment regimes however, all argue against the use of empiric treatment based on clinical evaluation alone" (Gill, C.P. & Cartwright, V.J. AIDS Clincal Care 6, 79-81, 1994)."