Thanh Hai Duong

White piedra and Trichosporon species in equatorial Africa. I. History and clinical aspects: an analysis of 449 superficial inguinal specimens.

Summary. White piedra is a hair infection characterized by nodules composed of fungal elements which envelop the hair shaft. Classically, this infection was considered to be produced by an asexual yeast‐like fungus, Trichosporon beigelii. At present, in accordance with studies carried out previously, this species is subdivided into six newly defined distinct species (T. asshu, T. ovoides, T. inkin, T. mucoides, T. asteroides and T. cutaneum), all belonging to the class Basidiomycetes. Although widespread, white piedra has not previously been described in tropical regions of Africa. The present study, carried out in Libreville (Gabon), an equatorial region of Africa, shows that the incidence of this infection is quite high (18% of 449. inguinal specimens) in the female population aged 15–60 years, with a predominance in young patients (15–44 years). The relationship between the clinical manifestations and the specific hair lesions is also detailed. Three species belonging to the genus Trichosporon were identified: T. mucoides, T. asahii and T. inkin.

White piedra and Trichosporon species in equatorial Africa. II. Clinical and mycological associations: an analysis of 449 superficial inguinal specimens

Summary. Eighty‐one of 449 Gabonese female patients examined were found to be positive for genitopubic white piedra. The association with trichobacteriosis is frequent (53 cases), and mostly seen with inguinal intertrigo. Fifty‐two strains belonging to the genus Trichosporon were isolated from genital hairs as well as from inguinal intertrigo lesions. These strains were identified in accordance with previously defined morphological and biochemical criteria. Three species were recognized. T. mucoides (25 strains), T. inkin (20 strains) and T. asahii (seven strains). Their macroscopic and microscopic morphological properties, as well as their ability to reduce tetrazolium, were determined. In addition, the study of the clinical and pathogenic associations in which each of these strains was involved revealed some of their particular properties.

Reduced Loa loa microfilaria count ten to twelve months after a single dose of ivermectin

The action of a single dose of ivermectin (200 micrograms/kg) on 71 Gabonese patients with Loa loa microfilariae in the peripheral blood, and living in areas highly endemic for loiasis, has been evaluated. Ten to 12 months after treatment, 43 patients (63%) had no circulating microfilaria and the geometric mean peripheral blood microfilaria count had decreased by 88.6% (P < 0.02). Thus, a single annual dose of ivermectin can markedly reduce loiasis transmission.

Fatal algaemia in patient with chronic lymphocytic leukemia.

To the Editor: Prototheca species are achlorophyllic lower algae, ubiquitous in nature, which can cause human infections, particularly in immunocompromised patients (1). Human protothecosis is mostly caused by P. wickerhamii and P. zopfii. Although such infections are infrequent, they can manifest themselves clinically as cutaneous lesions, olecranon bursitis, and, even more rarely, as disseminated or systemic infections (1). These infections occur in severely immunocompromised patients, such as persons with AIDS, or patients undergoing extensive treatment, such as cancer treatment or organ transplantation (1–4). We describe a fatal case of P. wickerhamii algaemia in a patient with chronic lymphocytic leukemia. In July 2007, a 79-year-old man, who had been monitored since 1993 for stage C chronic lymphocytic leukemia (5), was hospitalized July 13–20 for a depressive syndrome with fever, asthenia, and weight loss (3 kg over 2 months). Blood and urinary cultures on admission were sterile. The patient was hospitalized again on July 30 for fever (39°C), anorexia, and diarrhea, with ≈7 stools per day. He had lost 10 kg in 2 weeks. Blood cultures for bacteria (in BD Bactec Plus Aerobic/F and BD Bactec Lytic Anaerobic/F vials; Becton Dickinson, Le Pont de Claix, France) and fungi (BD Bactec Mycosis IC/F; Becton Dickinson) and stool cultures for bacteria were negative. Blood cultures were incubated in a Bactec 9240 instrument (Becton Dickinson). Aspergillus fumigatus was found in a bronchoalveolar lavage specimen, but no Aspergillus galactomannan antigen was detected in blood. The patient was treated with piperacillin-tazobactam, ciprofloxacin, acyclovir, voriconazole, and loperamide. Voriconazole (400 mg/day) was used from day 17 to day 27. On day 21, Cryptosporidium parvum was detected on parasitologic stool examination. Symptoms persisted on day 26, with strong asthenia and deterioration of general state. At that time, the leukocyte count was 178 × 109/L with 3.56 × 109/L polymorphonuclear neutrophils and 172 × 109/L lymphocytes. Three peripheral blood samples were cultured for detection of bacteria and fungi. On day 27, septic shock developed in the patient. A blood culture showed an Escherichia coli strain susceptible to piperacillin-tazobactam, aminoglycosides, and quinolones. Amikacin was added to the treatment regimen. Nonetheless, the patient died on day 28. Two blood cultures for bacteria in aerobic vials grew the day of the patient’s death, but tests of blood cultures for fungus remained negative. After Gram staining, gram-positive spherical unicellular organisms were observed (Figure). After 48 hours of incubation, creamy, yeast-like colonies grew on chocolate agar (bioMerieux, Marcy l’Etoile, France), but not on Sabouraud agar containing gentamicin and chloramphenicol (Becton Dickinson). Microscopy and the API 20C AUX system (bioMerieux) identified P. wickerhamii. Figure Gram-positive spherical unicellular organisms in a blood culture from a 79-year-old man with chronic lymphocytic leukemia. Magnification ×1,000. Sequencing the 18S rDNA with the primers Pw18SF 5′-TCAAAAAGTCCCGGCTAATCTCGTGC-3′ and Pw18SR 5′-CGCTTTCGTGCCTCAATGTCAGTGTT-3′ confirmed the identification. The sequence of the amplified product was compared with sequences published in the database of the National Center for Biotechnology Information (Bethesda, MD, USA). The most likely identification, according to BLAST analysis (www.ncbi.nlm.nih.gov/blast/Blast.cgi), was P. wickerhamii. In vitro susceptibility tests were performed by the Etest method (AB Biodisk, Solna, Sweden), on RPMI agar. P. wickerhamii was found to be susceptible to amphotericin B and posaconazole, with MICs of 0.047 μg/mL and 0.012 μg/mL, respectively. By contrast, it was resistant to fluconazole (MIC>256 μg/mL), voriconazole (MIC>32 μg/mL), and caspofungin (MIC>32 μg/mL). It was also susceptible to gentamicin (MIC = 0.25 μg/mL) but resistant to amikacin (MIC>24 μg/mL). However, the patient died before the algae were detected in the blood culture vials. In this case, antifungal treatment based on voriconazole use was empiric and ineffective. Some authors have described a successful treatment on localized protothecosis with voriconazole (6). Amphotericin B currently seems to be most effective agent, although the best treatment remains a matter of debate (1,4,7). Although in vitro susceptibility test results are not necessarily well correlated with results obtained in vivo, the low MIC of posaconazole reported here may be of interest in clinical practice (8). In the laboratory, use of selective yeast media, such as Sabouraud plus gentamicin, or Mycosis IC/F vials for blood culture, which contain chloramphenicol and tobramycin, may make it difficult to detect Prototheca spp., which are susceptible to these antimicrobial drugs.- In patients with algaemia, Prototheca spp. are often associated with bacteria, viruses, or yeasts which cause co-infections (1), as in this case, in which the alga was associated with E. coli. This association is probably the result of disseminated protothecosis in severely immunocompromised patients, and the alga may cross digestive or cutaneous barriers. Reasons for septic shock or death are unclear for most associations of pathogens (2,4). Prototheca spp. are found in various reservoirs, including the environment, animals, and food (1). In the case described here, the infection may have originated from a contaminated well used to obtain water for the patient’s kitchen garden. However, we were unable to test this hypothesis. Disseminated protothecosis is currently rare but, due to the algae’s ubiquitous nature, increasing use of immunosuppressive therapy, and increasing incidence of hematologic malignancy, Prototheca spp. may emerge as opportunistic pathogens. Prototheca spp. should also be considered as an emerging cause of systemic infection in immunocompromised patients.

White piedra and Trichosporon species in equatorial Africa. III. Identification of Trichosporon species by slide agglutination test.

Summary. Fifty‐two Trichosporon strains isolated from Gabonese female patients 15–60 years, were studied. The identity of these strains was established by two different methods: the method proposed by Guého et al. (1992), based on mycological criteria, and a slide agglutination method performed with monospecific antisera prepared in our laboratory. The final results show a perfect correlation between the two methods, which allowed us to identify 25 strains of T. mucoides, 21 strains of T. inkin and seven strains of T. asahii. The results of the agglutination tests performed with 24‐h‐old subcultures grown on Sabouraud glucose agar are available in less than 15 mins. In the light of these results, it appears that this method, which is rapid and easy to perform and reproduce, may readily be used in hospital laboratories. In addition, this method allowed us to verify the presence of antigens common to the genera Cryptococcus and Trichosporon, which were easily shown by the use of crude sera. The fact that the anti‐Triehosporon monospecific sera lose their capacity to agglutinate Cryptococcus neoformans proves their high specificity.

Cysticercose contractée en France métropolitaine

Resume Introduction Les cysticercoses diagnostiquees en France metropolitaine sont toutes d’importation. Nous rapportons une observation de cysticercose sous-cutanee decouverte chez un homme de 48ans qui n’a jamais quitte l’hexagone. Observation L’examen anatomo-pathologique d’un nodule sous-cutane extrait de la paroi abdominale d’un homme de 48 ans a permis de diagnostiquer une cysticercose. Il s’agissait d’une personne ayant toujours reside en France. Les differents examens par imagerie n’ont pas mis en evidence d’autres localisations. Cette personne, de meme que son entourage proche, n’etait pas porteuse de Taenia solium adulte dans son tube digestif. Commentaires Nous presentons un cas exceptionnel de cysticercose autochtone. S’agirait-il bien d’une cysticercose provoquee par la larve de Taenia solium? Cette eventualite est peu probable car ce tenia adulte n’est plus diagnostique en metropole depuis tres longtemps. Par contre, il existe en Auvergne un cestode parasite du renard qui pourrait accidentellement provoquer chez l’homme une cysticercose a Cysticercus crassiceps.

Diagnostic des parasitoses à parasites sanguicoles

Resume La parasitologie regroupe des parasites tres divers dont certains, parmi les plus graves, ont un developpement dans le sang, intracellulaires visibles apres coloration (plasmodies, Babesia , leishmanies et toxoplasmes), ou mobiles extracellulaires (trypanosomes et microfilaires). Leur mise en evidence ou diagnostic de certitude est le premier objectif vers lequel doit tendre toute technique biologique diagnostique et pronostique. Le diagnostic direct au microscope doit permettre d’identifier l’espece parasitaire en cause, son stade de developpement, et le nombre de parasites (parasitemie) chiffre indispensable a l’evaluation pronostique et au suivi therapeutique. Les techniques a mettre en œuvre comporteront l’examen direct reconnaissant les parasites extracellulaires mobiles entre les globules rouges ou l’examen de frottis ou gouttes epaisses colores. Il est souvent necessaire de faire appel a des techniques complementaires de concentration, filtration, culture ou inoculation a l’animal. Recemment, le developpement de techniques de biologie moleculaire permet d’accroitre la sensibilite et la specificite des methodes classiques. Cette avancee considerable, a la portee des laboratoires bien equipes, devra s’adapter aux situations de diagnostic a pratiquer en urgence a un cout acceptable. Dans certains cas de pauci parasitisme ou de necessite de diagnostic retrospectif, des techniques indirectes serologiques permettent de reconnaitre les stigmates du passage des parasites en dosant les anticorps ou antigenes circulants.