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Pneumocystis jirovecii is a unicellular organism that in individuals with impaired immunity may cause pneumonia that can progress from minor illness to severe inflammatory pneumonia (PCP) with respiratory failure and death. Despite antimicrobial prophylaxis, which has reduced the incidence of PCP, clusters of late infections have been reported among kidney transplant recipients worldwide. A nosocomial PCP cluster was first recognized in 2010 at a Sydney hospital, but PCP clusters have since occurred in almost half of the renal transplant units on the eastern Australian seaboard, refocussing attention on optimal prophylaxis regimens and the likelihood of patient-to-patient transmission. A consensus meeting was conducted to derive the lessons from this experience for responding to PCP outbreaks. These included: (1) acting quickly--clusters of PCP in kidney transplant recipients with patient-to-patient transmission required transplant programs to act quickly to institute prophylactic and treatment measures; (2) instituting universal prophylaxis for all patients seen in the affected unit; (3) reducing patient-to-patient transmission via airborne droplets in the outpatient waiting areas; (4) examining the P. jirovecii genotypes. The meeting also considered recommendations for the duration of prophylaxis following de novo transplant and, for the individuals in whom long term prophylaxis is required, separating units with and without clusters of PCP.

Although Pneumocystis carinii pneumonia is one of the leading causes of morbidity and mortality among patients with the acquired immunodeficiency syndrome, many questions about its epidemiology and transmission remain unanswered. Whereas traditional theory postulates that the disease results from reactivation of latent infection, recent data suggest that active acquisition of infection, either through environmental exposure or person-to-person transmission, may occur. This review summarizes the current state of knowledge about the epidemiology and transmission of P. carinii and reports on evolving techniques that may improve our understanding of this organism in the future.

Objective: To compare trends in nosocomial tuberculosis (TB) prevention measures and health-care worker (HCW) tuberculin skin test (TST) conversion of hospitals with HIV-related Pneumocystis carinii pneumonia (PCP) patients and other US hospitals from 1992 through 1996., Design and Setting: Surveys in 1992 and 1996 of 38 hospitals with PCP patients in four high-HIV-incidence cities and 136 other US hospitals from the American Hospital Association membership list., Participants: Twenty-seven hospitals with PCP patients and 103 other US hospitals., Results: In 1992, 63% of PCP hospitals and other US hospitals had rooms meeting Centers for Disease Control and Prevention (CDC) criteria (ie, negative air pressure, six or more air exchanges per hour, and air directly vented to the outside) for acid-fast bacilli isolation; in 1996, almost 100% had such isolation rooms. Similarly, in 1992, nonfitted surgical masks were used by HCWs at 60% of PCP hospitals and 68% at other US hospitals, while N95 respirators were used at 90% of PCP hospitals and 83% of other US hospitals in 1996. There was a significant decreasing trend in TST conversion rates among HCWs at both PCP and other US hospitals; however, this trend varied among all hospitals. HCWs at PCP hospitals had a higher risk of TST conversion than those at other US hospitals (relative risk, 1.71; p < 0.0001)., Conclusion: From 1992 through 1996, PCP and other US hospitals have made similar improvements in their nosocomial TB prevention measures and decreased their HCW TST conversion rate. These data show that most hospitals are compliant with CDC TB guidelines even before the enactment of an Occupational Safety and Health Administration TB standard.

Twenty-four perinatally HIV infected children received early treatment as soon as the diagnosis of viral contamination was established. In 13 cases (group 1), this diagnosis was based on a viremia and/or antigenemia during the first 6 months of life. In 11 cases (group 2), children were more than 15 months-old and had a positive HIV antibody test. Therapy included azidothymidine (AZT, 400 mg/m2/d) and the prevention of secondary infectious complications with intravenous immunoglobulin and cotrimoxazole. With a median follow-up of 26 months, we reported no case of severe secondary infection and no case of encephalopathy. Hematological side effects of AZT were rarely observed. Only one patient developed anemia. In all other cases, the only hematological abnormality was macrocytosis of red blood cells. Before treatment, the mean value of T4 cells age-adjusted count was 96, 86 and 91%, respectively, for groups 1, 2 and the entire study group. At the time of analysis, these values were 64, 62 and 63% respectively. This decrease was statistically significant for group 1 and for the entire study group, but did not reach statistical significance for group 2. These data show that AZT is probably insufficient as a long-term therapy for HIV infected children. Other therapeutic approaches need to be developed in the future, notably the combination of anti-retroviral drugs.