Antigenic relationship of Penicillium marneffei to P. primulinum

Penicillium marneffei infection and recent advances in the epidemiology and molecular biology aspects

Penicillium marneffei infection is an important emerging public health problem, especially among patients infected with human immunodeficiency virus in the areas of endemicity in southeast Asia, India, and China. Within these regions, P. marneffei infection is regarded as an AIDS-defining illness, and the severity of the disease depends on the immunological status of the infected individual. Early diagnosis by serologic and molecular assay-based methods have been developed and are proving to be important in diagnosing infection. The occurrence of natural reservoirs and the molecular epidemiology of P. marneffei have been studied; however, the natural history and mode of transmission of the organism remain unclear. Soil exposure, especially during the rainy season, has been suggested to be a critical risk factor. Using a highly discriminatory molecular technique, multilocus microsatellite typing, to characterize this fungus, several isolates from bamboo rats and humans were shown to share identical multilocus genotypes. These data suggest either that transmission of P. marneffei may occur from rodents to humans or that rodents and humans are coinfected from common environmental sources. These putative natural cycles of P. marneffei infection need further investigation. Studies on the fungal genetics of P. marneffei have been focused on the characterization of genetic determinants that may play important roles in asexual development, mycelial-to-yeast phase transition, and the expression of antigenic determinants. Molecular studies have identified several genes involved in germination, hyphal development, conidiogenesis, and yeast cell polarity. A number of functionally important genes, such as the malate synthase- and catalase-peroxidase protein-encoding genes, have been identified as being upregulated in the yeast phase. Future investigations pertaining to the roles of these genes in host-fungus interactions may provide the key knowledge to understanding the pathogenicity of P. marneffei.

Immunolocalization of secretory proteins of Aspergillus fumigatus using monospecific polyclonal antibodies in a murine model

The incidence of life-threatening mycoses caused by opportunistic fungi has increased dramatically in recent years with members of the genera Candida and Aspergillus being the most commonly encountered species. Prompt initiation of antifungal therapy for good prognosis of such cases is highly dependent on accurate diagnosis. The potential of metabolic antigens in the diagnosis of aspergillosis was investigated in the present study. Two proteins of 18 and 70 kDa were identified with success rate of 35% and 60% respectively based on their reactivity with patient sera of clinically diagnosed cases of aspergillosis. The antibodies raised against 70 and 18 kDa proteins in rabbits were found to be useful in detection of A. fumigatus in the kidneys of a mouse model of aspergillosis.

Usefulness of a microimmunodiffusion test for the detection of Penicillium marneffei antigenemia, antibodies, and exoantigens

Eight sera from culturally-proven cases of penicilliosis marneffei and their corresponding isolates were examined for circulating antibody(ies) and antigen, and exoantigens, respectively, using a microimmunodiffusion (MID) test. Two of the 8 sera produced strong precipitins (1-2) when reacted against control Penicillium marneffei antigen (5-week-old shaken cultures at 25 C) in the presence of control rabbit anti-P. marneffei serum. Five of the 8 sera produced a strong precipitin line when reacted against control hyperimmune serum to P. marneffei. These five sera, and one additional serum, which tested negative for antibody to P. marneffei, demonstrated the presence of antigen by reacting only against the anti-P. marneffei serum. Serological evaluations of the sera revealed that the MID test is capable of detecting antibody and antigen in AIDS patients having penicilliosis marneffei infections. Exoantigen analysis of the 8 P. marneffei isolates, which were previously identified using the conventional and time-consuming macro- and micro-morphological characteristics, showed the presence of 1 to 4 specific exoantigens in MID. With the exoantigen analysis, the identity of all of the isolates was confirmed as P. marneffei. Our studies indicated that the serological tests are useful for detecting circulating antibody and/or antigen in patients' sera, and that the exoantigen test is reliable for confirming the identity of P. marneffei cultures.

Western immunoblot analysis of protein antigens of Penicillium marneffei

Protein antigens of Penicillium marneffei prepared during the yeast and mould phases of in vitro growth were analyzed by gel electrophoresis and immunoblot assay. More than 20 yeast phase proteins were detected by Coomassie staining; among these, at least 10 reacted with IgG in the pooled sera of 28 AIDS patients with penicilliosis. Four immunogenic proteins of 200, 88, 54 and 50 kDa were produced in large quantity during the deceleration and early stationary phases of growth. When these proteins were reacted with individual sera derived from 33 AIDS patients with penicilliosis, reactivities to the 200, 88, 54 and 50 kDa protein were detected in 72.7, 93.9, 60.6 and 57.6%, respectively. The bands of 88, 54 and 50 kDa gave strong reactions with about a half of serum samples. In one serum derived from an AIDS patient, reactivities to the 54 and 50 kDa proteins could be strongly detected two months before the definite diagnosis by fungal culture. Protein components from the mould form were of lower yield and gave weaker signal in immunoblot analysis. These results indicate that at least two yeast-phase immunoreactive proteins (54 and 50 kDa) are relatively specific to the P. marneffei infection, thereby suggesting its potential for clinical application to the diagnosis of this emerging disease.

Hyalohyphomycosis caused by Paecilomyces variotii in an obstetrical patient

A case of hyalohyphomycosis, caused by Paecilomyces variotii, has been described in a 31-year-old female, who had undergone a cesarean section in her 39th week of pregnancy for a trial of labour. Five days following delivery, she complained of sharp, cramp-like pains, localized to the incisional site. She became febrile (38.2 degrees C). An ultrasound examination revealed a complex mass and fluid within the pelvis and upper abdomen. The fluid was drained by a needle aspiration and the patient was administered a regimen of antibacterial drugs. Microscopic examination did not reveal any bacteria in a gram stained preparation and cultures were negative as well. However, the fluid demonstrated a few segments of septate, hyaline hyphae, with cultures yielding a pure growth of P. variotii. An exoantigen procedure, currently under development, was helpful in confirming the identity of the patient's fungus. The patient's condition improved following needle aspiration and her recovery was uneventful. It is reiterated that certain infections, attributed to low-grade opportunistic pathogens, such as P. variotii, may be cured by proper surgical drainage.

Pulmonary penicillosis marneffei: report of the first imported case in Canada

A 57-year-old female, born in Laos and who had lived in Thailand prior to immigrating to Canada in 1989, was seen by her physician with a chief complaint of cough and dyspnea. Her chest X-ray showed bilateral pulmonary air fluid levels. A fungus, with a diffusible red pigment, tentatively identified as Penicillium marneffei, was isolated from the patient's bronchial washings and sputum specimens. At 37 degrees C, the fungus converted to a yeast form when cultured on brain heart infusion agar. Microscopic examination of this culture revealed yeast cells that reproduced by fission. The identity of the patient's isolate was confirmed as P. marneffei with an exoantigen test. The patient's serum demonstrated specific antibodies to P. marneffei antigen. Treatment with amphotericin B and ketoconazole resulted in clinical improvement, clearing of chest X-rays and conversion to sero-negativity. Our case is the first recorded diagnosis of imported penicillosis marneffei in Canada. The minimal inhibitory concentrations recorded for the patient's isolate to fluconazole, 5-fluorocytosine, itraconazole and miconazole were 12.5, 0.39, < 0.195 and < 0.195 micrograms/ml, respectively.

Treatment and serological studies of an Italian case of penicilliosis marneffei contracted in Thailand by a drug addict infected with the human immunodeficiency virus

A case of disseminated penicilliosis marneffei, the first to be diagnosed in Italy, is described in a male HIV-positive drug addict. The patient had visited Thailand several times in the two years prior to his hospitalization. The presenting signs were fever, productive cough, facial skin papules and pustules, nodules on both thumbs and oropharyngeal candidiasis. Penicillium marneffei was isolated from a series of blood specimens with the lysis centrifugation procedure. Septate, yeast-like cells were observed in histological sections of the nodules and sputum smears. The patient was treated for 6 weeks with amphotericin B (total dosage 1,400 mg) and flucytosine (150 mg/kg/die) for the first 3 weeks. Prompt clinical improvement and sterilization of all biological specimens were attained. Itraconazole was administered as maintenance therapy (400 mg/die for the first month and 200 mg afterward). During the follow-up period, no relapse was observed. The patient, however, did succumb to a variety of non-mycotic infections and died nine months after start of therapy. At autopsy, P. marneffei was not detected in his tissues. Serological studies were performed with a micro-immunodiffusion procedure using a mycelial culture filtrate antigen of P. marneffei. Sera taken early in the course of the disease gave positive antibody reactions. Whereas sera taken 3-5 months following therapy were negative. All known cases of penicilliosis marneffei in bamboo rats and in humans among the inhabitants and visitors to the endemic areas of P. marneffei in South East Asia and Indonesia are summarized.

Cutaneous manifestations of disseminated Penicillium marneffei mycosis in five HIV-infected patients

Five cases of disseminated Penicillium marneffei mycosis of Thai HIV patients, presented between November 1990 and April 1991, have been investigated. All patients were male and had bone marrow involvement. They showed mucocutaneous lesions with papules predominantly on the faces and upper extremities (5 cases), palatal papules (3 cases), and chronic genital ulcer (2 cases). P. marneffei was cultured, and the specific tissue form of the fungus was demonstrated histopathologically from skin and bone marrow specimens. In future, with increasing awareness of mucocutaneous lesions, disseminated penicilliosis in HIV-infected patients might be diagnosed sooner, thus leading to earlier therapy and better prognosis of the disease.