Caspofungin and Pneumocystis Pneumonia: It Is Time To Go Ahead

Current Concepts in the Diagnosis and Management of Pneumocystis Pneumonia in Solid Organ Transplantation

Pneumocystis infection manifests predominantly as an interstitial pneumonia in immunocompromised patients. Diagnostic testing in the appropriate clinical context can be highly sensitive and specific and involves radiographic imaging, fungal biomarkers, nucleic acid amplification, histopathology, and lung fluid or tissue sampling. Trimethoprim-sulfamethoxazole remains the first-choice agent for treatment and prophylaxis. Investigation continues to promote a deeper understanding of the pathogen's ecology, epidemiology, host susceptibility, and optimal treatment and prevention strategies in solid organ transplant recipients.

Incidence of Pneumocystis pneumonia in Immunocompromised Patients without Human Immunodeficiency Virus with Intravenous Pentamidine Prophylaxis: A Systematic Review and Meta-Analysis

Background: Trimethoprim-sulfamethoxazole (TMP-SMX) is a first-line Pneumocystis pneumonia pneumonia) (PCP) prophylaxis agent, but monthly intravenous pentamidine (IVP) is used in human immunodeficiency virus (HIV)-uninfected immunocompromised hosts because IVP is not associated with cytopenia and delayed engraftment. Method: We performed a systematic review and meta-analysis to estimate breakthrough PCP incidence and adverse reactions in HIV-uninfected immunocompromised patients receiving IVP. MEDLINE, Embase, Web of Science, Cochrane Library, and ClinicalTrials.gov were searched from their inception until 15 December 2022. Results: The pooled incidence of breakthrough PCP with IVP was 0.7% (95% CI, 0.3–1.4%, 16 studies, 3025 patients) and was similar when used as first-line prophylaxis (0.5%; 95% CI, 0.2–1.4%, 7 studies, 752 patients). The pooled incidence of adverse reactions was 11.3% (95% CI, 6.7–18.6%, 14 studies, 2068 patients). The pooled adverse event-related discontinuation was 3.7% (95% CI, 1.8–7.3%, 11 studies, 1802 patients), but was lower in patients receiving IVP monthly (2.0%; 95% CI 0.7–5.7%, 7 studies, 1182 patients). Conclusion: Monthly IVP is an appropriate second-line agent for PCP prophylaxis in certain non-HIV immunocompromised hosts, especially in patients with hematologic malignancies and hematopoietic stem cell transplant recipients. Using IVP for PCP prophylaxis as an alternative to oral TMP-SMX while patients are unable to tolerate enteral medication administration is feasible.

Prognostic factors and clinical efficacy of second-line treatments of Pneumocystis jirovecii pneumonia for non-HIV patients after first-line treatment failure

Background

Pneumocystis jirovecii pneumonia (PCP) is a life-threatening opportunistic infection. In non-HIV immunocompromised patients with PCP, a standard second-line treatment has not been established up to now.

Methods

Non-HIV immunocompromised patients with confirmed PCP between April 2013 and December 2020 were included. Their PCP treatment history was tracked. Factors related to first-line trimethoprim/sulfamethoxazole (TMP/SMX) and second-line treatment failure were identified. Different second-line treatment strategies were compared.

Results

Among the 220 patients, 127 (57.73%) did not respond to first-line TMP/SMX treatment. Risk factors related to treatment failure included symptom triad with breathlessness at rest, persistent fever and cough (85% in the treatment failure group versus 74% in the treatment success group, P = 0.034), treatment with invasive mechanical ventilation (67 vs. 19%, P < 0.001), coinfection with CMV (69 vs. 47%, P = 0.035), and bacteremia (59 vs. 10%, P < 0.001). A total of 49 patients received second-line treatment on the basis of TMP/SMX, and 28 (57.1%) of them responded to the treatment. No clinical parameter, including selection of different therapies, was found to be significantly associated with second-line treatment failure. Further, the prognosis of different second-line therapies showed no drug or drug combination strategy superior to others. The primaquine group had lower 90-day mortality rate (45.9%) but showed no statistically significant difference compared with the non-primaquine group (64.6%). The patients in the clindamycin plus primaquine group had the lowest in-hospital mortality rate (22.2%, P = 0.042) among different second-line therapies, although the in-hospital mortality of the primaquine group was not significantly different from that of the non-primaquine group. The differences in 28 day mortality and overall mortality rates were not statistically significant, too.

Conclusion

CMV infection and bacteremia were risk factors significantly associated with treatment failure of TMP/SMX. The response and survival rates of second-line treatment, including clindamycin, primaquine, and caspofungin, were poor, maybe clindamycin plus primaquine as second line treatment was better than other treatment strategies. These results suggest that clinicians should carefully evaluate whether the treatment of TMP/SMX has failed due to a coinfection rather than hastily changing to a second-line drug when the patient worsens.

Deletion of cox7c Results in Pan-Azole Resistance in Aspergillus fumigatus

In Aspergillus fumigatus, the most prevalent resistance to azoles results from mutational modifications of the azole target protein Cyp51A, but there are non-cyp51A mutants resistant to azoles, and the mechanisms underlying the resistance of these strains remain to be explored. Here, we identified a novel cytochrome c oxidase, cox7c (W56*), nonsense mutation in the laboratory and found that it caused reduced colony growth and resistance to multiantifungal agents. Meanwhile, we revealed that cold storage is responsible for increased tolerance of conidia to itraconazole (ITC) stress, which further advances azole-resistant mutations (cryopreservation→ITC tolerance→azole resistance). The deletion or mutation of cox7c results explicitly in resistance to antifungal-targeting enzymes, including triazoles, polyenes, and allylamines, required for ergosterol synthesis, or resistance to fungal ergosterol. A high-performance liquid chromatography (HPLC) assay showed that the cox7c knockout strain decreased intracellular itraconazole concentration. In addition, the lack of Cox7c resulted in the accumulation of intracellular heme B. We validated that an endogenous increase in, or the exogenous addition of, heme B was capable of eliciting azole resistance, which was in good accordance with the phenotypic resistance analysis of cox7c mutants. Furthermore, RNA sequencing verified the elevated transcriptional expression levels of multidrug transport genes. Additionally, lower itraconazole-induced reactive oxygen species generation in mycelia of a cox7c-deletion strain suggested that this reduction may, in part, contribute to drug resistance. These findings increase our understanding of how A. fumigatus’s direct responses to azoles promote fungal survival in the environment and address genetic mutations that arise from patients or environments.

Pneumocystis Pneumonia: Immunity, Vaccines, and Treatments

For individuals who are immunocompromised, the opportunistic fungal pathogen Pneumocystis jirovecii is capable of causing life-threatening pneumonia as the causative agent of Pneumocystis pneumonia (PCP). PCP remains an acquired immunodeficiency disease (AIDS)-defining illness in the era of antiretroviral therapy. In addition, a rise in non-human immunodeficiency virus (HIV)-associated PCP has been observed due to increased usage of immunosuppressive and immunomodulating therapies. With the persistence of HIV-related PCP cases and associated morbidity and mortality, as well as difficult to diagnose non-HIV-related PCP cases, an improvement over current treatment and prevention standards is warranted. Current therapeutic strategies have primarily focused on the administration of trimethoprim-sulfamethoxazole, which is effective at disease prevention. However, current treatments are inadequate for treatment of PCP and prevention of PCP-related death, as evidenced by consistently high mortality rates for those hospitalized with PCP. There are no vaccines in clinical trials for the prevention of PCP, and significant obstacles exist that have slowed development, including host range specificity, and the inability to culture Pneumocystis spp. in vitro. In this review, we overview the immune response to Pneumocystis spp., and discuss current progress on novel vaccines and therapies currently in the preclinical and clinical pipeline.

Antifungal drugs: An updated review of central nervous system pharmacokinetics

Invasive fungal infections (IFIs) in the central nervous system (CNS) are particularly hard to treat and are associated with high morbidity and mortality rates. Four chemical classes of systemic antifungal agents are used for the treatment of IFIs (eg meningitis), including polyenes, triazoles, pyrimidine analogues and echinocandins. This review will address all of these classes and discuss their penetration and accumulation in the CNS. Treatment of fungal meningitis is based on the antifungal that shows good penetration and accumulation in the CNS. Pharmacokinetic data concerning the entry of antifungal agents into the intracranial compartments are faulty. This review will provide an overview of the ability of systemic antifungals to penetrate the CNS, based on previously published drug physicochemical properties and pharmacokinetic data, for evaluation of the most promising antifungal drugs for the treatment of fungal CNS infections. The studies selected and discussed in this review are from 1990 to 2019.