Laboratory investigation of Pneumocystis carinii pneumonia.

Abstract

Introduction Unexpected Pneumocystis carinii pneumonia (PCP) led to the identification of the acquired immunodeficiency syndrome (AIDS). The laboratory diagnosis ofP carinii infection has had a less auspicious start. As this fungus is not easily grown, there has been a tendency for physicians to make a clinical diagnosis. Early and rapid confirmation ofthe diagnosis ofPCP is important and the development of sensitive and specific tests has made such evaluation possible.1 This paper will critically examine the different types of specimen and the laboratory techniques used for the identification of P carinii. The role of serology will be discussed. The fact that the vast majority of AIDS patients develop PCP during their illness2 has been a great stimulus to research into PCP. Yet, it must be remembered that PCP is also a major problem for other immunocompromised patients in whom the pathology may be different, and other laboratory tests such as serology may be more relevant.34 Consequently diagnosis of P carinii infection in AIDS and nonAIDS patients will be considered. In the future newer laboratory techniques may increase the sensitivity of diagnosis. Recently the polymerase chain reaction has been applied to the diagnosis of PCP with considerable success.5 However, all of the laboratory techniques, both new and old, have advantages and disadvantages. In addition, the use of prophylaxis and greater awareness of PCP by clinicians will result in earlier diagnosis, and the role of laboratory tests in this changing environment needs careful assessment. This paper attempts to identify a rational approach to the investigation of P carinii infection in terms of the types of specimens and tests. Department of Microbiology, Raigmore Hospital, Inverness 1V2 3UJ, UK Specimens J MW Chatterton There are essentially three types of specimen D 0 HoYen for the demonstration of P carinii: sputum, Correspondence to bronchoalveolar secretions and biopsy Dr Ho Yen Accepted for publication material. Each type of specimen has had a 16 March 1992 wide range of diagnostic success in different