Identification of Differentially Expressed Genes in Nocardia brasiliensis Induced by Progesterone and Dihydrotestosterone Using Differential Display PCR

Sex steroid hormones have an important physiological role in humans. They can also affect the gene expression of many organisms, including bacteria. In Mexico, Nocardia brasiliensis is the main causative agent of actinomycetoma, a granulomatous disease more frequent in men than women, which is thought to be related to a higher occupational risk in men. Therefore, it has been suggested that differences in clinical presentation could be related to sex steroid hormone levels. Attempting to explain the differences in actinomycetoma prevalence between men and women, in this work, the effect of progesterone and dihydrotestosterone on the genetic expression of N. brasiliensis was investigated using a differential display polymerase chain reaction assay. The results showed that both hormones affected the expression of genes encoding proteins related to central metabolism and hypothetical proteins with unknown functions. This study also demonstrated the utility of differential display in this modern era and provided a first approach to the effect of sex hormones on N. brasiliensis gene expression.

Antifúngicos poliénicos. Mecanismo de acción y aplicaciones

The first compounds with specific antifungal activity were identified in the middle of the last century as a product of the secondary metabolism of bacteria of the order Actinomycetales, and their clinical use significantly diminished the morbidity and mortality associated with severe fungal infections. Many of such biosynthetic compounds are characterized by a chemical polygenic structure, with a variable number of carbon-carbon double bonds. Currently, besides polygenic antimycotics, there are other antifungal agents, such as the azole compounds, that have less toxicity in patients; however, cases of therapeutic failure with such compounds have been documented, therefore, the use of polygenics is still the best alternative in such cases. This review presents data about the properties and applications of antifungal-polygenic compounds using amphotericin B as a model. Key words: Amphotericin B; antifungal polyenes; ergosterol

[Esophageal candidiasis in patients from a specialty hospital]

BACKGROUND

Esophageal candidiasis (EC) is the most common cause of infectious esophagitis. So far, its main risk factor has been HIV infection; in recent years, EC has been favoured by the increasing of diabetes mellitus, wide-spread use of acid-lowering agents, broad-spectrum antibiotics, and inhaled steroids. In Mexico EC has been poorly studied.

OBJECTIVES

To determine the clinical and epidemiological characteristics of EC, and to identify its etiological agents as well as its antifungal susceptibility.

METHODS

Patients who revealed the presence of scattered white spots through an upper gastrointestinal system endoscopy, in a period of one year, in a tertiary care hospital, were included. Samples from patches were collected for microscopic examination, culture, and susceptibility tests.

RESULTS

Out of 1763 patients studied, 23 had scattered white spots, and most of them presented Kodsi grade I; 13 were men; half of the patients were between the ages 20 to 40; main comorbidity was liver cirrhosis; use of omeprazole was significant. 22 isolates were obtained from 17 patients. The most frequent species were C. albicans (14) and C. parapsilosis (3). In five cases we found a two-species association v. g. Candida famata with Trichosporon mucoides. Half of the isolates showed resistance to one or several antifungal drugs.

CONCLUSIONS

EC frequency in this study was similar to other studies’ results. Obtained isolates showed high resistance to azolic compounds and to caspofungin, which is relevant information to take a therapeutic decision.

[First report of infectious endocarditis due to Histoplasma capsulatum in Mexico]

BACKGROUND

Infectious endocarditis of fungal origin is rare but of high mortality. The agents involved are mainly opportunists of the genus Candida and Aspergillus; however other fungi can also cause this disease.

CLINICAL CASE

The case of a woman who suffered unknown origin intermittent fever for several months; and in who, by blood culture (after lysis-centrifugation) and molecular biology techniques, Histoplasma capsulatum was identified as etiological agent. The histological study showed abundant intracellular yeasts and hyphae in intracardiac vegetations.

CONCLUSION

This first report of infectious endocarditis by H. capsulatum in Mexico highlights the importance of using in addition to manual blood culture (lysis-centrifugation) and histological study, faster and more sensitive diagnostic methods, such as serology and molecular biology, to confirm or rule out an invasive fungal infection and identify the agents.

Molecular detection of candida species from hospitalized patient’s specimens

Objective

To identify the most frequent Candida species in specimens from patients hospitalized in different medical centers of Mexico City, with suspected fungal infection.

Methods

Specimens were grown on Sabouraud dextrose agar at 28°C for 72 h. In addition, DNA was extracted. Isolates were grown on CHROMagar Candida™, at 37°C for 48 h. The molecular identification was performed by polymerase chain reaction (PCR) using primers specific for four species.

Results

Eighty one specimens were processed and included: bronchial lavage, pleural, cerebrospinal, peritoneal, ascites and bile fluids; blood, sputum, bone marrow, oro-tracheal cannula and ganglion. By culture, 30 samples (37%) were positive, and by PCR, 41 (50.6%). By PCR, the frequency of species was: Candida albicans 82.9%, Candida tropicalis 31.7%, Candida glabrata 24.4%, and Candida parapsilosis 4.9%. In 34.1% of specimens a species mixture was detected suggesting a co-infection: Two species in five specimens (C. albicans-C tropicalis and C. albicans-C glabrata), and three species in three specimens (C. albicans-C. glabrata-C. tropicalis).

Conclusions

The PCR is an useful tool for detection the most common Candida species causing infection in hospitalized patients, it avoids the requirement of culture weather we start from clinical specimen and it favors the early diagnosis of invasive candidiasis.

[Frequency of invasive fungal infections in a Mexican High-Specialty Hospital. Experience of 21 years]

BACKGROUND

Factors such as cancer, HIV infection, use of corticosteroids and antibiotics, favors the increase in the number of invasive fungal infections (IFI) worldwide.

METHODS

To determine the frequency and epidemiological aspects of IFI at a mexican, a review of the proven cases diagnosed over the past 21 years (1993-2013) in the Laboratory of Medical Mycology was performed.

RESULTS

A total of 472 cases were identified as: 261 candidiasis, 82 mucormycosis, 60 cryptococcosis, 43 aspergillosis and 16 histoplasmosis. A decrease in the frequency of candidiasis was observed, with 74 cases in the first 6 years and 48 in the last five. C. albicans was the most common agent and pulmonary infection the most prevalent. Cryptococcosis also declined from 24 to 10 cases, mainly caused by C. neoformans; two cases of C. laurentii and C. terreus and C unigutulatus were isolated once. Mucormycosis remained steady, but aspergillosis increased significantly, and from 2 cases found in the first studied period, it rose to 23 in the last one.

CONCLUSIONS

It is important that High Specialty Hospitals have well-equipped laboratories of Medical Mycology. We suggest the creation of a National Reference Center for Mycoses to collect all the data of these infections, in order to help to the development of strategies for health education, prevention, diagnosis and treatment of them.

Endophthalmitis of probable endogenous origin caused by Scedosporium boydii: A case report

BACKGROUND

Mycotic ocular infections caused by the Scedosporium apiospermum species complex are challenging to treat because of the delayed diagnoses and poor responses to antifungal drugs and surgical treatment.

CASE REPORT

A case of a 69-year-old male patient with a history of diabetes mellitus type 2 and prior surgery on the right femur is described. In the 10 days prior to the ophthalmic consultation he started with ocular pain, adding to a previous and progressive loss of visual acuity in his right eye. The diagnosis of endophthalmitis of probable endogenous origin was established. Despite medical treatment, the patient's condition worsened and, due to the imminent risks, an enucleation was performed. Smears of the enucleation tissue revealed fungal cells, and the cultures yielded a fungus belonging to the S. apiospermum species complex, which was identified as Scedosporium boydii by morphological characteristics and sequencing of a PCR amplicon.

CONCLUSIONS

A diagnosis of endophthalmitis of probable endogenous origin in the right eye was based on a previous right femur surgery. Potential risk to the patient led to enucleation.

[Onychomycosis frequency in psoriatic patients in a tertiary care hospital]

BACKGROUND

The changes in psoriatic nails can closely resemble an onychomycosis. Therefore, the fungal infection may be underdiagnosed. It was investigated the frequency of mycosis in fingernails and toenails in 150 patients with psoriasis in a dermatology department.

METHODS

The clinical data suggestive of onychomycosis were investigated. Nail scales were obtained and cultured on Sabouraud dextrose agar with and without antibiotic. A direct examination with KOH was also performed.

RESULTS

Out of 150 patients, 67 (45 %) had healthy nails; 42 (28 %) presented onychomycosis and 41 (27 %) showed nail changes without infection. Fingernail changes were more associated with psoriatic onychopathy (82.5 %), unlike toenail changes that were more frequently caused by fungal infection (26.4 % vs. 9.45 % in psoriasis). Out of 20 positive cultures, 22 fungi were isolated, of which 11 belonged to Candida spp. (50 %). As risk factor to develope an onychomycosis, only the psoriasis evolution time showed a significant difference (p = 0.033).

CONCLUSIONS

In patients with psoriasis, fingernail disorders are mainly due to the own disease, while toenail disorders changes can be associated with onychomycosis. The main etiological agents were yeasts from the genus Candida. The only factor associated with a higher incidence of onychomycosis in these patients was a long lasting psoriasis.

Paracoccidioidomycosis in Mexico: clinical and epidemiological data from 93 new cases (1972-2012)

Paracoccidioidomycosis (PCM) is an endemic systemic infection in several countries of Latin America. The few registered cases in Mexico most likely do not reflect the real frequency. Disseminate the epidemiological and clinical data of unreported cases of PCM in Mexico from 1972 until 2012 is the aim of this work. Epidemiological and clinical information of non-published cases of PCM was requested from the principal mycological diagnosis centres in Mexico. A total of 93 cases were received. The infection was found predominantly in men (95.7%), peasants (88.5%) and individual between 31 and 60 years of age. Most of the cases were found in tropical areas of the Gulf of Mexico (54.84%) and the Pacific littoral (20.3%). The main sites of dissemination were the oral mucosa (39.38%) and skin (34.05%). The most effective treatments were itraconazole alone and the combination of itraconazole with sulfamethoxazole-trimethoprim. PCM is a subdiagnosed pathology in Mexico. Therefore, adequate training is necessary to determine the current status of this mycosis.

[Update on the epidemiology of mycetoma in Mexico. A review of 3933 cases]

Mycetoma is one of the most frequent chronic subcutaneous infections in many tropical and subtropical regions.

OBJECTIVE

To update the epidemiological data of mycetoma cases in Mexico.

METHOD

A survey in the main mycological diagnosis centers in this country was performed. Each mycologist was requested for number of diagnosed mycetoma cases, age, sex, occupation, geographic origin, type of mycetoma, and etiological agents.

RESULTS

Until 2012, we have registered 3,933 cases in the last 54 years. Sex distribution corresponds to 75.6% for men and 24.4% for women. In 75.72% is present in adults between 16-50 years old. The predominant work group of patients is farmers (58.41%) followed by housewives (21.79%). Most of patients come from Jalisco, Morelos, Nuevo Leon, Guerrero, Veracruz and Michoacan states. The most affected body areas are limbs (60.29%) and trunk (19.76%). Actinomycetoma has a frequency of 96.52%, and the commonest etiological agent is Nocardia brasiliensis (65.58%). Eumycetoma (3.48%) is mainly caused by Madurella grisea (28.47%) and M. mycetomatis (26.28%).

CONCLUSIONS

Mycetoma is an under-diagnosed pathology representing a health problem in rural regions and must be attended with more interest by the health institutions.

[Invasive mycosis, immunocompromise and fever of unknown origin]

BACKGROUND

fungal invasive infections are frequent in patients with immunosuppression. A common clinical feature is the presence of fever of unknown origin (FUO) in any of its several presentations. The aim of this study was to know the frequency of FUO associated to invasive mycosis in hospitalized patients.

METHODS

samples from 34 patients were studied by immunological and microbiological procedures in order to investigate candidiasis, cryptococcosis, aspergillosis and Pneumocystis infection.

RESULTS

fungal infection diagnosis was established in 12 (35 %) from 34 patients who full criterion. The fungal species isolated were Candida albicans (six), Aspergillus fumigates (four) and Cryptococcus sp. (two). All candidiasis cases were diagnosed only by microbiological studies, aspergillosis by immunological and microbiological studies, and cryptococcosis only by immunological studies.

CONCLUSIONS

we concluded that is important the searching of mycosis in immunocompromised patients with fever of unknown origin by microbiological and immunological procedures.

[Onychomycosis-causing yeasts in four Mexican dermatology centers and their antifungal susceptibility to azolic compounds]

BACKGROUND

Yeasts represent the second cause of nail fungal infection in the world, and Candida albicans and Candida parapsilosis are the two most common species.

OBJECTIVES

To determine the yeast species frequency and their in vitro antifungal susceptibility, obtained from patients with clinical features suggestive of onychomycosis.

METHODS

A prospective study was carried out in four dermatological care centers in Mexico from 2004 to 2007. Clinical diagnosis was corroborated by direct examination and culture. The yeast species was determined by morphological and biochemical tests. An antifungal susceptibility test to ketoconazole, itraconazole and fluconazole by the broth microdilution method was performed on each isolate (document M27-A2).

RESULTS

One hundred sixty-six yeast isolates were obtained; the most frequently found species were C. parapsilosis (31.9%), C. albicans (22.4%) and Candida guilliermondii (12.7%). Of all isolates, 51 showed resistance to one or several of the azole compounds: 33 to itraconazole, 12 to ketoconazole and 6 to fluconazole. It was remarkable that the four Candida glabrata isolates were resistant to the three azole compounds; C. guilliermondii and Candida famata were resistant to itraconazole in 42.9% and 54.5%, respectively.

CONCLUSION

The results obtained show the importance of identifying the aetiological agent and antifungal susceptibility testing in order to avoid therapeutic failures in onychomycosis.

Dynamics of dermatophytosis frequency in Mexico: an analysis of 2084 cases

We analysed 15,101 biological samples from patients presenting with superficial mycoses who attended outpatient services over a 10-year period. Scale samples were processed for direct microscopic examination with 15% KOH and cultured on Sabouraud glucose agar plus chloramphenicol and cycloheximide. Laboratory examination confirmed 4,709 cases of superficial mycosis (31.18%), of which 2,084 (44.26%) were dermatophytoses. The species most frequently encountered was Trichophyton rubrum (71.2%), followed by T. tonsurans (6.9%), T. mentagrophytes (5.5%), Microsporum canis (4.5%) and Epidermophyton floccosum (1.3%). The most frequent clinical form of dermatophytosis was tinea unguium (59.9%), followed by tinea pedis (24.5%). We demonstrate that the number of cases of T. rubrum is increasing in Mexico.

[Mycotic keratitis in an eye care hospital in Mexico City]

BACKGROUND

Some of the most common precipitating events for keratomycoses (fungal keratitis), include surgical trauma (after cornea transplantation), the use of contaminated contact lenses or alterations in lacrimal secretions. Diagnosis and treatment (to avoid loss of vision) for these type of infections are challenging.

OBJECTIVE

Retrospective review of the diagnosis, epidemiology, etiology and response to treatment in 219 patients with fungal keratitis in Mexico.

METHODS

We have studied the diagnosis, epidemiology, etiology and response to treatment in 219 patients from different states in the Mexican Republic in the Cornea Department at an Ophthalmology Hospital in Mexico D.F.

RESULTS

Trauma was the precipitating event in 77 patients (36%), of which 12 (5.4%) were due to surgical trauma; 152 patients (64.8%) did not report any prior trauma. There were 165 male (75.3%) and 54 female (24.6%) patients, with an average age of 46 years old. For clinical and visual treatment patients were treated with topical and oral antifungals and surgery. One or more surgeries were performed on a total of 81 patients (36.9%). A total of 62 patients (28.3%) received a corneal transplant, and 19 patients (8.7%) were subjected to conjunctival flap or scleral-conjunctival surgery.

CONCLUSIONS

In Mexico, keratomycoses affect mostly male patients in a 4:1 ratio over females. Fusarium solani was the most frequent agent of fungal keratitis in our study (37.2%), and the highest number of corneal ulcers and eviscerations (26%) was present in patients infected by Aspergillus. The best therapeutic responses were with combination of topical antifungals against dematiaceous fungi.

[Candiduria in type 2 diabetes mellitus patients and its clinical significance. Candida spp. antifungal susceptibility]

BACKGROUND

Candida is frequently seen in urinalysis studies in patients with diabetes mellitus. The objective was to determine the presence and clinical significance of candiduria, and to identify the different isolated Candida species and their in vitro susceptibility pattern to different antifungal agents by means of the broth microdilution method.

METHODS

We studied the urine from 50 type 2 diabetes mellitus (DMT2) patients. 24 patients had controlled DMT2 and 26 non-controlled DMT2.

RESULTS

Twenty-three Candida spp. positive cultures were obtained, of which 17 were obtained from the non-controlled DMT2 patients; 30.7% of the isolates were caused by Candida infection. The main isolated species were C. glabrata (48%) and C. albicans (35%). Itraconazole, amphotericine B, and ketoconazole showed less antifungal activity in C. glabrata isolates, whereas fluconazole and voriconazole displayed higher antifungal activity.

CONCLUSIONS

It is important to search routinely for yeast in the urine of DMT2 patients to detect candidiasis, and to perform antifungal susceptibility tests to Candida isolates in order to establish antifungal therapy for these patients.

[Antifungal resistance: an emerging problem in Mexico]

BACKGROUND

An increase in mycosis associated with therapeutic failure has been observed worldwide. The dearth of data in Mexico led us to study antifungal resistance.

MATERIAL AND METHODS

Seventy six isolates of patients from the Hospital de Especialidades, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social were included: 36 with dermatophytoses and 40 with candidiasis. Dermatophytes were assesed using the E-test method and Candida spp. using the broth microdilution method. Antifungal drugs included itraconazole, ketoconazole and fluconazole for dermatophytes; in addition, voriconazole and amphotericin B were used to treat yeasts.

RESULTS

From the 36 dermatophytes, seven isolates (19.4%) showed resistance to one or more antifungal drugs: three to Trichophyton rubrum, three to T. mentagrophytes and one to T. tonsurans. One T. rubrum isolate was resistant to the three azoles; the other six isolates were resistant to fluconazole only. From the 40 Candida isolates, 11 (27.5%) showed resistance: seven to ketoconazole and itraconazole; three only to itraconazole and one to ketoconazole. One C. glabrata isolate showed resistance to the four azoles. None of the yeasts showed resistance to amphotericin B.

CONCLUSION

Therapeutic failure could be caused by drug resistance. In our study we found an antifungal resistance of 20% and 27.5% in dermatophytes and in yeasts respectively.

[Micosis among five highly underprivileged Mexican communities]

BACKGROUND

In many small rural communities in Mexico, medical care is deficient, empirical or absent.

OBJECTIVE

In order to improve health coverage in rural areas, the Mexican Institute of Social Security organizes Medical and Surgical Meetings of various specialties including Dermatology and Mycology (MSDM). These include visits to rural hospitals by dermatologists and a mycologist to care for underprivileged communities. In addition to taking samples, they establish the clinical diagnosis and indicate medical and/or surgical treatment, with follow-up visits when needed.

MATERIAL AND METHODS

In 2004 and 2005, five MSDM in Chiapas (two), Puebla (one), Michoacán (one) and Oaxaca (one) were organized. Mycoses were within the first four skin pathologies detected.

RESULTS

Direct examination with potassium hydroxide led to the diagnosis of mycosis and other skin diseases such as scabies, pediculosis or hair disorders. The sample cultures showed, in addition to common fungi as dermatophytes (Trichophyton rubrum, 19 cases), other uncommon fungal agents such as Trichosporon spp, Chrysosporium spp, Cryptococcus, Geotrichum spp and Aspergillus spp. Most of the candidiasis cases were caused by Candida parapsilosis (nine cases) followed by C. albicans (three cases).

[Antifungal and phagocytic immunostimulation treatment of chronic disseminated dermatophytosis]

A 39 years old man with a long-standing disseminated dermatophytosis even with several antifungal treatments is presented. From lesions, Trichophyton rubrum var. typical downy, T. tonsurans and Candida albicans were isolated and showed sensivity to azolic compounds in vitro. The phagocytic activity in vitro compared with normal control was depressed. Treatment with itraconazole and immunomodulation using a bacterial antigen was indicated. During the last two years the patient has been clinical and mycologically healthy, and his phagocytosis activity has become normal. In patients with chronic and relapsing dermatophytosis, the immune response evaluation is recommended, and immunomodulation could be useful as a rational measure in patients with a particular immunodeficiency.

[Detection of Coccidioides immitis infection in Coahuila, Mexico]

Coccidioidomycosis is a mycosis firstly pulmonar caused by Coccidioides immitis; it can be disseminated to central nervous system, bones and skin, principaly. In Mexico, the real frequency of the disease is unknown. The aim of this work was to determine, by skin test and by serology, the infection cases by C. immitis in twelve communities (10 rural and two urban), attended in the Hospital Rural No 79 at the Instituto Mexicano del Seguro Social (IMSS) from the Coahuila State, Mexico. Six hundred and sixty eight adult individuals of both sexes were studied, to whom 0.1 ml of coccidioidin by intradermal route was applied; 72 h after, the induration diameter was measured. One hundred eighty individuals were selected and seric anti-C. immitis immunoglobulins levels were determined by ELISA. Six hundred twenty one individuals (93%) were positive to coccidioidin, the frequency was much higher than that previously reported in Coahuila. From 180 sera studied, the means of optical density (OD) were: IgG1, 1.55; IgG2, 0.94; total IgG, 0.33; IgG3, 0.29; IgG4, 0.27; IgM, 0.08. The values of IgG1, IgG2 and IgM compared with the other immunoglobulins were statistically significant. The high values of IgG1 and IgG2 suggest frequent contact with the antigen, and probable cases of undiagnosed disease.

Cytokine production and lymphocyte proliferation in patients with Nocardia brasiliensis actinomycetoma

IFN-gamma, TNF-alpha, IL-4, IL-10 and IL-12 concentrations in the supernatant of peripheral blood mononuclear cell (PBMC) cultures and the in vitro proliferation of PBMC were studied in 25 patients with actinomycetoma caused by Nocardia brasiliensis and in 10 healthy controls from endemic zones. Cell cultures were stimulated by a N. brasiliensis crude cytoplasmic antigen (NB) and five semi-purified protein fractions (NB2, NB4, NB6, NB8, and NB10) separated by isoelectric. Phytohemagglutinin (PHA) and purified protein derivative (PPD) of Mycobacterium tuberculosis were used as control antigens. Skin tests were performed by injecting 0.1 ml of candidin and PPD intradermally (ID). Patients showed a poor response to tuberculin, while their response to candidin was more than two fold greater than that observed in the controls. Cell proliferation showed no statistically significant differences in either group. IFN-gamma production was higher in the healthy controls than in the patients, whereas TNF-alpha secretion was slightly higher in the patients' cultures. IL-4 was detected in the patients' cultures but not in the controls. IL-10 and IL-12 were present at low concentrations in both groups. These results suggest that patients with actinomycetoma show normal antigen recognition, but with low IFN-gamma production, and higher concentrations of IL-4, IL-10 and TNF-alpha in the patients' PBMC cultures, indicating that they probably have a Th2 type of immune response.

[Immunoglobulins in patients with Nocardia brasiliensis actinomycetoma]

Considering that some authors have reported an increasing of some immunoglobulins in actinomycetoma patients, in this study we propose to determine differential production of IgG1, IgG2, IgG3, IgG4 and IgGM in 25 patients with actinomycetoma and 25 healthy individuals from a mycetoma endemic area. Immunoglobulins were determined by ELISA technique. To sensibilize the plates, six Nocardia brasiliensis antigens were used: a crude antigen denominated NB and five derivatives (NB2, NB4, NB6, NB8 and NB10) obtained by their isoelectric point. Results showed that all IgG subclasses were higher in the patients' sera than in control sera, with a maximal difference to IgG3 and IgG4. To the latter subclass, six antigens were highly reactives. IgM levels were similar in both groups. As it occurs in other infections, in the actinomycetoma pathogenesis probably participate the increase or deficiency of a determined immunoglobulin class, as well as the relationship between different subclasses.

[Unknown fixed cutaneous sporotrichosis]

Sporotrichosis is the most frequent subcutaneous mycosis in Mexico. The clinical forms are commonly described as lympho-cutaneous and cutaneous-fixed. The case of a male patient who developed an eritematous plaque with radial growth is reported. The patient received empirical therapy and topic steroids which modified the clinical picture with vesicles to vesicles, ulcers and blood and honey crusts. Diagnosis of fixed cutaneous sporotrichosis incognito was established by clinical, mycological and histopathological studies. Delayed cellular immunity in vitro and in vivo were normal. The patient received oral itraconazole showing clinical and mycological cure after four months.

[Frequency of mycosis in immunosuppressed patients at a regional hospital of Mexico City]

OBJECTIVE

To isolate and identify the fungi in specimens collected from immunocompromised patients seen in Mexico City hospital, and to assess their association with mycosis.

MATERIAL AND METHODS

A total of 268 specimens from 108 patients were processed for mycological study, including direct examination, smears, cultures, and microcultures in specific media, in addition to biochemical tests. Most of the patients had been diagnosed with pulmonary tuberculosis and Acquired Immunodeficiency Syndrome (AIDS).

RESULTS

One hundred and eighty-three yeasts and 66 mycelial fungi were isolated. Forty-five mycoses were diagnosed; the most frequent mycosis was pulmonary candidosis (32 cases). Candida albicans and C parapsilosis were the predominant species associated with mycotic infection. Five Cryptococcus neoformans var. neoformans, one C albidus, three Histoplasma capsulatum and one Geotrichum candidum isolates were associated with mycosis.

CONCLUSIONS

Of the studied patients, 41.6% showed a mycotic infection, principally associated with AIDS and pulmonary tuberculosis. The English version of this paper is available at:http://www.insp.mx/salud/index.html.

Fungal peritonitis in 15 patients on continuous ambulatory peritoneal dialysis (CAPD). Fallberichte. Pilz-Peritonitis bei 15 Patienten mit ambulanter Dauerperitonealdialyse (CAPD)

Peritonitis is a frequent complication in patients with chronic renal failure on continuous ambulatory peritoneal dialysis (CAPD) treatment. The aim of this study was to know the prevalence of fungal peritonitis on patients undergoing CAPD, and to determine the antifungal susceptibility pattern of the identified isolates. Samples of the peritoneal dialysis fluid from 165 patients on CAPD treatment with peritonitis manifestations were submitted to mycological study (direct microscopic examination, culture and antifungal susceptibility test). Ten Candida isolates were identified, being C. albicans and C. parapsilosis the most common species. From isolates obtained, three species (C. albicans, C. parapsilosis, and C. guilliermondii) presented itraconazole resistance while C. glabrata was resistant to both itraconazole and ketoconazole. Aspergillus fumigatus was associated to peritonitis in three cases and Acremonium sp. in two.

[Mycoses frequency in three communities in the North mountain of the State of Puebla]

In order to know mycosis frequency in the North of the State of Puebla, Mexico, in habitants from the communities of Ayotoxco, Mazatepec and Zacatipan were studied. Previous medical study biological samples were submitted to direct examination, smear and culture. Histoplasmin and sporotrichin skin test were applied to 57 individual from Zacatipan. From 110 patients 146 mycological studies were performed. Eighty six cases (59%) of mycosis were detected: 43 finger or toenails onychomycosis, 25 tinea pedis, seven tinea capitis, four cases of tinea manum and, finally, five cases of seborrhoeic dermatitis and two of pitiriasis versicolor. We isolated: 18 streins of dermatophytes, mainly Trichophyton rubrum and T. mentagrophytes (11 and 5 strains respectively); 12 cultures of non-dermatophytes filamentous fungi; six cases of mycelia sterile; six yeast strains, most of them Candida spp but none C. albicans. From 57 patients to whom skin tests were applied, five of them (8.8%) were positive to both antigens; ten positive (17.6%) only to histoplasmin and eight (14%) to sporotrichin. This study showed that rural population from Puebla present a high frequency of superficial mycosis (61% of mycological studies). Considering the percentage of positive skin test we suppose that there are many not diagnosed sporotrichosis and histoplasmosis cases.

Effectiveness of terbinafine in the eradication of Microsporum canis from laboratory cats

In this study, the coats of 20 cats with no dermatophytosis lesions were sampled for colonization by Microsporum canis, which was isolated in 45% of cases. All cats were treated with oral terbinafine for 3 weeks. The drug was administered orally at a daily dosage 8.25 mg kg-1. Mycologic status was assessed at the end of the treatment; and after follow-up at 2 days, and 4 and 9 weeks. The final evaluation revealed a complete mycologic cure of all cats by obtaining negative cultures, thereby demonstrating that terbinafine is an effective method of eradication of dermatophyte colonization.

[Identification and typing of yeast isolates from hospital patients in Mexico City]

Nosocomial yeast infections have become a major cause of morbidity and mortality in immunocompromised patients. This study presents the frequency of yeasts isolated from different biological products from a Mexico City hospital's patients during one year. C. albicans was isolated in 72.3% of patients, followed by C. glabrata (13.4%) and C. parapsilosis (8%). Twenty different morphotypes were identified and the serotype B was the most frequent (79%).

Nocardia brasiliensis: in vitro and in vivo growth response to steroid sex hormones

As actinomycetoma is more frequent in males than in females, the possibility that hormones might modify the Nocardia brasiliensis growth and the course of experimental actinomycetoma was explored. Five N. brasiliensis strains were grown on Sabouraud agar containing estradiol, progesterone or testosterone, in 3 different concentrations. Colony diameters were measured weekly for 7 weeks. N. brasiliensis strains were also grown in Sabouraud broth containing hormones. Glucose concentration was measured weekly for 6 weeks. Finally, experimental actinomycetoma was produced in male and female hormone-treated mice. Invasion rate, plantar pad diameter and positive retrocultures were assessed. In vitro experiments showed that progesterone and testosterone inhibit N. brasiliensis growth, manifested by lower colony diameters and greater glucose concentrations. In vivo experiments demonstrated that estradiol limits actinomycetoma development. Progesterone and testosterone induced greater diameters of inoculated plantar pads and greater invasion rates with greater positive culture numbers than estradiol. Results partially explain the resistance of females to actinomycetoma.

Dermatophytoses in Mexico City

We analysed 2350 biological samples from patients with a clinical diagnosis of superficial mycoses who attended outpatient services over a 7-year period. Samples of scales were processed by direct microscopic examination with 15% KOH and cultured on Sabouraud glucose agar with chloramphenicol and cycloheximide. Laboratory examination confirmed dermatophytosis in 860 (36.6%) cases, of which 80.9% were caused by Trichophyton rubrum. The most frequently observed dermatophytoses were tinea unguium (60%) and tinea pedis (25.6%). In agreement with previous observations, we demonstrate that T. rubrum continues to increase in Mexico.

[Exoenzymes of dermatophytes isolated from acute and chronic tinea]

The presence of five enzymes (deoxyribonuclease, elastase, lipase, caseinase and hemolysin) in 76 strains of dermatophytes 47 of Trichophyton rubrum, 10 of T. mentagrophytes, five of T. tonsurans, 10 of Microsporum canis and four of Epidermophyton floccosum) isolated from 30 cases of acute dermatophytosis and from 46 chronic ones was determined by a qualitative plate assay; in the same way, the presence of these five enzymes with the acute and chronic dermatophytosis was correlated. It was observed that three of the enzymes were produced by the strains with a meaningful frequency; deoxyribonuclease was produced by 84.2% of the strains; elastase by 82.9%; and lipase by 65.8%. In T. rubrum the DNase was produced in 100% of strains. DNase and elastase were related to fungi which caused acute or chronic dermatophytosis in 93.3/78.2% and 96.6/74% respectively. On the other hand, lipase was present in 76% of strains, the ones that caused the chronic infections.