[The Usefulness of the Scan with 67Ga-citrate to Assess the Therapeutic Effect on Pneumocystis pneumonia with HIV-1 Infection].

Objective: Peumocystis pneumonia (PCP) is one of the common opportunistic infections with severe respiratory failure, and is sometimes life-threatening in patients with the acquired immunodeficiency syndrome. Although treatment for PCP is established, an appropriate treatment period has not been evaluated to clarify the risk factors for immune reconstitution inflammatory syndrome (IRIS) associated with PCP.

Method: We retrospectively analyzed the clinical characteristics of risk factor, which are the treatment period for PCP, and 67Ga scintigraphy (Ga-S) at the 21st day from the start of the treatment for PCP, with 21 cases of PCP and HIV infection treated during 2005-2012 at Kyushu Medical Center.

Result: The rate of residual uptake by Ga-S was assessed in 17 cases (81%). Four cases were diagnosed as being PCP-IRIS, and residual uptake by Ga-S was detected in all PCP-IRIS cases. The durations of the therapy were classified into three groups: 21 days, 28 days, and 35 days. All PCP-IRIS cases were treated in the period of 28 days. In contrast, in 11 cases that showed residual uptake by Ga-S, and were treated for PCP in 35 days, PCP-IRIS did not occur. Additionally, there were 4 cases in which residual uptake by Ga-S did not occur. They were treated with PCP for only 21 days, but did not show PCP-IRIS.

Conclusion: In this study, we showed that Ga-S is useful to evaluate the therapeutic effect. Furthermore, we found that the occurrence of PCP-IRIS could be prevented with the early start of cART after 21 days treatment for PCP, when residual uptake by Ga-S after the first treatment for PCP was not detected. It may also be possible to start cART in the early phase after its treatment without the occurrence of PCP-IRIS with the appropriate additional treatment of PCP for 14 days. These guidelines for treatment of PCP in HIV-infected adults and adolescents have been recommended for the duration of 21 days since 1984. We propose that for the prevention of PCP-IRIS, it is nessecory to reconsider recommendation for the treatment duration of 21 days, and meanwhile to evaluate the treatment effect of PCP with Ga-S, because PCP resistance to sulfa drugs, namely are trimethoprim-sulfamethoxazole, is beginning to appear.