Powel Kazanjian

Pneumocystis carinii Mutations Are Associated with Duration of Sulfa or Sulfone Prophylaxis Exposure in AIDS Patients

This study was conducted to determine whether Pneumocystis carinii dyhydropteroate synthase (DHPS) gene mutations in AIDS patients with P. carinii pneumonia (PCP) are affected by duration of sulfa or sulfone prophylaxis and influence response to sulfa or sulfone therapy. The P. carinii DHPS genes from 97 AIDS patients with PCP between 1991 and 1999 from 4 medical centers were amplified, using polymerase chain reaction (PCR), and sequenced. Mutations were observed in 76% of isolates from patients exposed to sulfa or sulfone prophylaxis compared with 23% of isolates from patients not exposed (P=.001). Duration of prophylaxis increased the risk of mutations (relative risk [RR] for each exposure month, 1.06; P=.02). Twenty-eight percent of patients with mutations failed sulfa or sulfone treatment; mutations increased the risk of sulfa or sulfone treatment failure (RR, 2.1; P=0.01). Thus, an increased duration of sulfa or sulfone prophylaxis increases the chance of developing a P. carinii mutation. The majority of patients with mutations respond to sulfa or sulfone therapy.

Pneumocystis carinii mutations associated with sulfa and sulfone prophylaxis failures in AIDS patients

Background:Failures of prophylaxis against Pneumocystis carinii pneumonia (PCP) in AIDS patients do occur, but no evidence for drug resistance has yet been presented. Objective:To determine whether mutations in the sulfa and sulfone drug target are associated with failure of prophylaxis using a sulfa-containing agent. Methods:Portions of the gene for P. carinii dihydropteroate synthase (DHPS), the sulfa and sulfone target, from 27 patients (20 of whom had AIDS) diagnosed with PCP between 1976 and 1997 were amplified using polymerase chain reaction and sequenced. Seven of the 27 patients (all of whom had AIDS) were receiving sulfa or sulfone drugs as prophylaxis for PCP. Results:Mutations were found at only two amino-acid positions and were significantly more common in patients who received sulfa/sulfone prophylaxis. Mutations were observed in five (71%) out of seven isolates from AIDS patients receiving sulfa/sulfone as prophylaxis compared with only two (15%) out of 13 specimens from AIDS patients who did not (P = 0.022). No mutations were seen in isolates from seven non-HIV-infected patients, none of whom were on prophylaxis. Mutations were only observed in specimens obtained in 1995–1997. Conclusions:Mutations in two amino-acid positions were significantly more common in AIDS patients with PCP who failed sulfa/sulfone prophylaxis. These amino acids appeared to be directly involved in both substrate and sulfa binding, based on homology to the Escherichia coli DHPS crystal structure. Thus, the results were consistent with the possibility that mutations in the P. carinii DHPS are responsible for some of the failures of sulfa/sulfone prophylaxis in AIDS patients.

Pneumocystis carinii Pneumonia in Patients in the Developing World Who Have Acquired Immunodeficiency Syndrome

We review Pneumocystis carinii pneumonia (PCP) in patients in the developing world (i.e., Africa, Asia, the Philippines, and Central and South America) who have acquired immunodeficiency disease (AIDS). During the first decade of the AIDS pandemic, PCP rarely occurred in African adults. More recent reports have noted that PCP comprises a significantly greater percentage of cases of pneumonia than it did in the past. This trend dramatically contrasts with that observed in industrialized nations, where a reduction in the number of cases of PCP has occurred as a result of the widespread use of primary P. carinii prophylaxis and highly active antiretroviral therapy. Throughout the developing world, the rate of coinfection with Mycobacterium tuberculosis and PCP is high, ranging from 25% to 80%. Initiation of treatment when PCP is in an advanced stage may account for the high mortality rates (20%-80%) associated with pediatric PCP in the developing world.

Sequence Polymorphisms in the Pneumocystis carinii Cytochrome b Gene and Their Association with Atovaquone Prophylaxis Failure

Atovaquone (Mepron, 566c80) is an effective agent against Pneumocystis carinii, which probably acts by binding to cytochrome b and inhibiting electron transport. To assess the possibility that atovaquone resistance might be developing, the genes for the cytochrome b from P. carinii sp. f. carinii and P. carinii sp. f. hominis were partially sequenced. Eight of 10 patient isolates had cytochrome b genes with the same amino acid sequence. The P. carinii cytochrome b genes from 2 of 4 patients who had atovaquone prophylaxis failure contained mutations resulting in amino acid changes in one of the ubiquinone (coenzyme Q) binding sites (Qo). These mutations are homologous to mutations in other microorganisms that confer resistance to similar inhibitors. Variations in the sequence of the P. carinii cytochrome b gene suggest but do not prove the development of drug resistance.

Granulocyte colony-stimulating factor administration to HIV-infected subjects augments reduced leukotriene synthesis and anticryptococcal activity in neutrophils.

Neutrophil (PMN) dysfunction occurs in HIV infection. Leukotrienes (LT) are mediators derived from the 5-lipoxygenase (5-LO) pathway that play a role in host defense and are synthesized by PMN. We investigated the synthesis of LT by PMN from HIV-infected subjects. There was a reduction (4.0+/-1.3% of control) in LT synthesis in PMN from HIV-infected compared with normal subjects. This was associated with reduced expression of 5-LO-activating protein (31.2+/-9.6% of normal), but not of 5-LO itself. Since HIV does not directly infect PMN, we considered that these effects were due to reduced release of cytokines, such as granulocyte colony-stimulating factor (G-CSF). We examined the effect of G-CSF treatment (300 microgram daily for 5 d) on eight HIV-infected subjects. PMN were studied in vitro before therapy (day 1) and on days 4 and 7. LTB4 synthesis was increased on day 4 of G-CSF treatment, and returned toward day 1 levels on day 7. 5-LO and 5-LO-activating protein expression were increased in parallel. As a functional correlate to this increase in PMN LT synthesis by G-CSF, we examined the effects on killing of Cryptococcus neoformans. Anticryptococcal activity of PMN from HIV-infected subjects was less than that of PMN from normal subjects. G-CSF treatment improved fungistatic activity of PMN. This increase in antifungal activity was attenuated by in vitro treatment with the LT synthesis inhibitor, MK-886. In conclusion, PMN from HIV-infected subjects demonstrate reduced 5-LO metabolism and antifungal activity in vitro, which was reversed by in vivo G-CSF therapy.

Pneumocystis carinii cytochrome b mutations are associated with atovaquone exposure in patients with AIDS

This retrospective cohort study was conducted to determine whether Pneumocystis carinii cytochrome b gene mutations in patients with AIDS and P. carinii pneumonia (PCP) are associated with atovaquone exposure. Portions of the P. carinii cytochrome b genes that were obtained from 60 patients with AIDS and PCP from 6 medical centers between 1995 and 1999 were amplified and sequenced by using polymerase chain reaction. Fifteen patients with previous atovaquone prophylaxis or treatment exposure were matched with 45 patients with no atovaquone exposure. Cytochrome b coenzyme Q binding site mutations were observed in 33% of isolates from patients exposed to atovaquone, compared with 6% from those who were not (P=.018). There was no difference in survival 1 month after treatment between patients with or without cytochrome b mutations (P=.14). Thus, cytochrome b mutations are significantly more common in patients with AIDS and PCP with atovaquone exposure, but the clinical significance of these mutations remains unknown.

HIV Protease Inhibitors: Advances in Therapy and Adverse Reactions, Including Metabolic Complications

Protease inhibitors (PIs) effectively inhibit replication of the human immunodeficiency virus (HIV), and reduce mortality and prolong survival in patients with HIV infection. Newer PIs saquinavir (soft gelatin capsule) and amprenavir, as well as other PIs, may be effective when administered twice/day. Adverse reactions may occur, as well as metabolic complications and interactions between PIs and other drugs, including other PIs. The strategy of combining PIs is based on specific pharmacologic interactions among the agents.

Human Immunodeficiency Virus—Associated Fever of Unknown Origin: A Study of 70 Patients in the United States and Review

To characterize the clinical features of human immunodeficiency virus (HIV)-associated fever of unknown origin (FUO) in the United States, we performed a retrospective analysis of cases that fulfilled specific criteria (published by Durack and Street in 1991) at two medical centers in the United States between 1992 and 1997. Seventy cases met criteria for HIV-associated FUO; the mean CD4 cell count was 58/mm3, and the mean duration of fever was 42 days. A cause of FUO was found in 56 of the 70 cases; 43 were of a single etiology, and in 13 cases multiple conditions were established. The most common diagnoses were disseminated Mycobacterium avium infection (DMAC; 31%), Pneumocystis carinii pneumonia (13%), cytomegalovirus infection (11%), disseminated histoplasmosis (7%), and lymphoma (7%). In this United States series, FUO occurs most often in the late stage of HIV infection, individual cases often have multiple etiologies, and DMAC is the most common diagnosis.

Pneumocystis carinii mutations associated with sulfa and sulfone prophylaxis failures in immunocompromised patients

Recent studies have shown that mutations in two amino acid positions of the Pneumocystis carinii dihydropteroate synthase gene are significantly more common in immunocompromised patients with P. carinii pneumonia who fail sulfa or sulfone prophylaxis. This paper reviews the studies that suggest that these mutations may be responsible for some failures of prophylaxis in P. carinii.

Recurrence of Mycobacterium avium Infection in Patients Receiving Highly Active Antiretroviral Therapy and Antimycobacterial Agents

The known effects of highly active antiretroviral therapy (HAART) on opportunistic infections (OIs) range from immune restoration disease to remission of specific OIs. In the present study, Mycobacterium avium complex infection recurred in 3 patients receiving antimycobacterial therapy and HAART. At the time of the initial M. avium infection, the mean CD4 cell count was 22.3 cells/mm3, and the HIV viral load was 181,133 copies/mL. Relapse occurred a mean of 14. 3 months after the first episode; the mean follow-up CD4 cell count was 89/mm3 (mean elevation of 66 cells/mm3), and the HIV viral load was <400 copies/mL in each patient. M. avium was isolated from blood (1 patient), blood and lymph node (1), and small-bowel tissue (1). M. avium infection may recur as a generalized or focal disease in those who are receiving antimycobacterial agents but whose HAART-associated CD4 cell recovery, although significant, is not optimal.