Usefulness of beta-d glucan in diagnosing Pneumocystis carinii pneumonia and monitoring its treatment in a living-donor liver-transplant recipient

Opportunistic Infections in Patients with HTLV-1 Infection

As an acquired immunodeficiency, human immunodeficiency virus (HIV) infection is primarily responsible for opportunistic infections in infected patients. However, opportunistic infections also occur in individuals with human T cell lymphotrophic virus type 1 (HTLV-1) infection. Here, we report opportunistic infections in two Japanese HTLV-1-seropositive patients. The first patient was a 67-year-old male, who had cytomegalovirus infection associated with esophagogastritis and terminal ileitis. The patient was HTLV-1-positive and was diagnosed with smoldering adult T cell leukemia (ATL). High levels of serum soluble IL-2 receptor (sIL-2R; 4,304 U/mL) and an increased percentage of CD4+CD25+ T cells (75.5%) in peripheral blood were also detected. The second patient was a 78-year-old female, a known asymptomatic HTLV-1 carrier, who presented with persistent herpes zoster, followed by Pneumocystis jirovecii pneumonia. Disease progression of smoldering ATL along opportunistic infections was observed with very high levels of serum sIL-2R (14,058 U/mL) and an increased percentage of CD4+CD25+ T cells (87.2%) in peripheral blood. In patients with suspected opportunistic infections, both HTLV-1 and HIV should be considered. In HTLV-1-positive patients, an increase in the CD4+CD25+ T cell subset may have its value as a prognostic marker.

Pneumocystis pneumonia in children

Pneumocystis pneumonia (PCP) is a life-threatening infection in immunocompromised children with quantitative and qualitative defects in T lymphocytes. At risk are children with lymphoid malignancies, HIV infection, corticosteroid therapy, transplantation and primary immunodeficiency states. Diagnosis is established through direct examination or polymerase chain reaction (PCR) from respiratory secretions. Trimethoprim-sulphamethoxazole is used for initial therapy in most patients, while pentamidine, atovaquone, clindamycin plus primaquine, and dapsone plus trimethoprim are alternatives. Prophylaxis of high-risk patients reduces but does not eliminate the risk of PCP. Improved understanding of the pathogenesis of PCP is important for future advances against this life-threatening infection.

Pneumocystis pneumonia: current concepts in pathogenesis, diagnosis, and treatment

Pneumocystis pneumonia (PCP) is an infection of the lungs caused by the opportunistic fungal genus Pneumocystis. In humans, PCP is a serious and potentially life-threatening infection occurring in immunocompromised individuals, particularly those who have AIDS, or following immune suppression from malignancy, organ transplantation, or therapies for inflammatory diseases. Several recent studies have contributed to understanding of the biology and pathogenesis of the organism yielding new diagnostic approaches and therapeutic targets. Although trimethoprim-sulfamethoxazole remains the mainstay of prophylaxis and treatment, ongoing concerns for emerging Pneumocystis resistance supports the continuing investigation for novel therapeutic agents.

Biofilm formation by Pneumocystis spp

Pneumocystis spp. can cause a lethal pneumonia in hosts with debilitated immune systems. The manner in which these fungal infections spread throughout the lung, the life cycles of the organisms, and their strategies used for survival within the mammalian host are largely unknown, due in part to the lack of a continuous cultivation method. Biofilm formation is one strategy used by microbes for protection against environmental assaults, for communication and differentiation, and as foci for dissemination. We posited that the attachment and growth of Pneumocystis within the lung alveoli is akin to biofilm formation. An in vitro system comprised of insert wells suspended in multiwell plates containing supplemented RPMI 1640 medium supported biofilm formation by P. carinii (from rat) and P. murina (from mouse). Dramatic morphological changes accompanied the transition to a biofilm. Cyst and trophic forms became highly refractile and produced branching formations that anastomosed into large macroscopic clusters that spread across the insert. Confocal microscopy revealed stacking of viable organisms enmeshed in concanavalin A-staining extracellular matrix. Biofilms matured over a 3-week time period and could be passaged. These passaged organisms were able to cause infection in immunosuppressed rodents. Biofilm formation was inhibited by farnesol, a quorum-sensing molecule in Candida spp., suggesting that a similar communication system may be operational in the Pneumocystis biofilms. Intense staining with a monoclonal antibody to the major surface glycoproteins and an increase in (1,3)-beta-D-glucan content suggest that these components contributed to the refractile properties. Identification of this biofilm process provides a tractable in vitro system that should fundamentally advance the study of Pneumocystis.

Advances in the biology, pathogenesis and identification of Pneumocystis pneumonia

PURPOSE OF REVIEW

Pneumocystis pneumonia remains the most prevalent opportunistic infection in patients with AIDS. It is also a common devastating infection in patients with other causes of altered immunity. Though scientific study of this fungal pathogen is challenging given the inability to propagate the organism outside of the host lung, studies utilizing advanced molecular techniques and genomic analysis have broadened our understanding of the epidemiology and pathogenesis of Pneumocystis and will be described herein.

RECENT FINDINGS

Results from advanced molecular techniques suggest that Pneumocystis organisms not only cause infection in patients with impaired immunity but also colonize mammals with normal immune systems. Advanced technology has also identified acquired Pneumocystis genetic mutations that confer resistance to currently utilized therapeutics. Though not yet widely utilized in clinical medicine, advanced polymerase chain reaction techniques improve the diagnostic yield of respiratory specimen analysis. Preliminary results from serum beta-glucan testing suggest that a noninvasive marker of Pneumocystis pneumonia infection and response to therapy may be on the horizon.

SUMMARY

Recent scientific advances suggest opportunities for improving the diagnosis and treatment surveillance of Pneumocystis pneumonia. Further investigations are necessary to define the optimal characteristics of these laboratory tests and to develop therapeutics directed at novel Pneumocystis genomic targets.