Showing papers in "Revista Argentina De Microbiologia in 2007"

Biofilm formation by Stenotrophomonas maltophilia isolates from device-associated nosocomial infections.

Abstract: Medical devices are often colonized by bacteria which may cause severe infections. The aim of this work was to evaluate biofilm formation by S. maltophilia isolates from device-associated nosocomial infections. The 13 local iso- lates exhibited different capacities of biofilm formation on hydrophilic and hydrophobic surfaces. All isolates formed strong biofilms in polystyrene microplates, while strong, moderate or weak biofilms were detected in borosilicate (BS) or polypropylene (PP) tubes. The proficiency of biofilm formation was better evaluated by the level of crystal violet staining expressed relative to the final culture density. The microscopic analysis of biofilms formed on glass coverslips revealed the presence of a matrix of exopolysaccharides and microcolonies typical of biofilm architecture. Isolates with increased adhesion to BS showed larger microcolonies. According to our results, twitching correlated well with attachment to the three abiotic surfaces tested, while swimming only showed a slight correlation with biofilm formation on PP. Poor correlation was observed between cell surface hydrophobicity and biofilm formation. One of the highest biofilm-producing isolates adhered to urethral catheters of different materials, and exhibited an increased resistance to oxidative stress, one of the common stresses encountered by bacteria during the infection process due to the immune response.

Prolonged fecal shedding of Shiga toxin-producing Escherichia coli among children attending day-care centers in Argentina.

Abstract: In this report we describe the detection and duration of fecal shedding of Shiga toxin-producing Escherichia coli (STEC) O157 and non-O157 in symptomatic and asymptomatic cases during four events occurred among children in day-care centers in Argentina. In each event, the cases were identified among children, family contacts and staff members of the Institution. The isolates were characterized by pheno-genotyping and subtyping methods. The STEC fecal shedding was prolonged and intermittent. Strains O157:H7 (1 st event); O26:H11 (2 nd event); O26:H11 (3 rd event) and O145:NM (4th event) were shed during 23-30, 37, 31 and 19 days, respectively. Considering the possibility of STEC intermittent long-term shedding, symptomatic and asymptomatic individuals should be excluded from the Insti- tution until two consecutive stool cultures obtained at least 48 h apart, test negative.

Situación de las micosis en la República Argentina

Abstract: Epidemiological status of mycoses in the Argentine Republic. We herein report the results of a retrospective nationwide survey on mycoses diagnosed between January and December, 2004. The study included data provided by 72 laboratories located in 19 provinces and in Buenos Aires City. Out of 801,805 microbiological specimens processed that year, only 62,681 (8%) were submitted to mycological studies. A total of 23,600 mycoses cases were diagnosed: 11,107 (47%) superficial mycoses, 10,830 (46%) mucosal candidiasis and 1,663 (7%) deep mycoses. Relative frequencies of superficial mycoses did not differ significantly (p>0.05) from frequencies observed in a previous study covering Buenos Aires City and Province (1993), and from two countrywide surveys conducted by the National Network of Mycology Laboratories and National Quality Control Program (NNML and NQCP) in 1999 and 2002. The most frequent deep mycoses were yeast fungaemia (34 %), cryptococcosis (20%), broncho-pulmonary aspergillosis (13%), histoplasmosis (11%), paracoccidioidomycosis (7%) and pneumocystosis (5%). In contrast with results of four previous nationwide studies on broncho-pulmonary mycoses including a survey performed by NNML and NQCP in 2002, our study revealed that histoplasmosis prevailed over paracoccidioidomycosis, thus ranking for the first time as the most frequent endemic mycosis in Argentina.

Fungal peritonitis in patients on peritoneal dialysis: twenty five years of experience in a teaching hospital in Argentina.

Abstract: Fungal peritonitis is a rare but serious complication of peritoneal dialysis The aim of this study was to analyze peritonitis rates, associated factors, clinical course, microbiological aspects, therapeutic regimens, and outcome of patients with fungal peritonitis in the dialysis center of a teaching hospital over the last 25 years A hundred and eighty three episodes of peritonitis were detected and microbiologically documented in 57 patients Fungi were identified in eight episodes (437%) occurring in seven female patients The fungal peritonitis rate was 006 episodes/patient-year Gram and Giemsa stains were positive in five out of eight dialysate fluids The causative microorganisms were: Candida albicans in five episodes, and Candida parapsilosis, Candida glabrata, and Neosartorya hiratsukae in the remaining three Antibiotics were administered to all but one patient, within 3 months before fungal peritonitis was detected All patients required hospitalization, and antifungal therapy was administered in all episodes The Tenckhoff catheter was removed in seven out of eight fungal peritonitis All patients recovered from the fungal episodes In the group of patients studied, it is concluded that recent exposure to antibiotics and female sex, were strongly associated with the development of fungal peritonitis by yeasts The peritonitis caused by the environmental filamentous fungus did not require antibiotic pressure Direct microscopy of the dialysate pellet was extremely useful for the prompt management of the fungal episode Fungal peritonitis preceded by multiple episodes of bacterial peritonitis always determined the definitive dropout of the patient from the peritoneal dialysis program Patients with de novo yeast-related peritonitis could continue on the program

Vigilancia de Neisseria meningitidis en Argentina, 1993-2005: distribución de serogrupos, serotipos y serosubtipos causantes de enfermedad invasiva

Abstract: Neisseria meningitidis is an important cause of meningitis, bacteremia and septic shock syndrome. We herein present the distribution of serogroups, serotypes and serosubtypes of 2244 isolates of N. meningitidis from patients with meningitis or meningococcemia, received within the period 1993-2005, in the National Reference Laboratory, INEI-ANLIS "Dr. Carlos G. Malbran", from 33 Argentine hospitals that are included in a National Network devoted to for the study of bacterial meningitis. Between 1993-1995, serogroup B was prevalent (66%) whereas in the period from 1995-2001, serogroup C prevailed (65%). However, following but after that period, the prevalence of serogroup B was recovered. In the last 5 years of the studied period, the serogroups Y and W135 represented as a whole a 15.6% as a whole whereas up to the year 2000 during the first 6 years they accounted for it was of 4.7%. Higher diversity in the distribution of serotypes and serosubtypes was observed within serogroup B. The nonsubtypable isolates throughout the period of study represented the 52.8%, this high percentage demonstrates the limited capacity of the serotyping for the determination of meningococcal/meningococcus subtypes. of meningococco.

Aislamiento, caracterización y subtipificación de cepas de Escherichia coli O157:H7 a partir de productos cárnicos y leche

Abstract: Resumen es: Escherichia coli productor de toxina Shiga (Stx) (STEC) O157:H7 es un patogeno asociado a enfermedades transmitidas por alimentos, fundamentalmente de or...

Seasonal fluctuations in prevalence of dog intestinal parasites in public squares of Mar del Plata city, Argentina and its risk for humans.

Abstract: Resumen en: The aim of this work is to analyze whether there is a seasonal prevalence of parasites in dog feces from public squares in Mar del Plata city, Argentina,...

Infecciones adquiridas en la comunidad por Staphylococcus aureus resistente a meticilina en un hospital de agudos

Abstract: Methicillin- resistant Staphylococcus aureus (MRSA) is one of the most prevalent pathogens associated with nosocomial infections. However, most recently, MRS...

Resistencia a los antimicrobianos de aislamientos de Escherichia coli obtenidos de cerdos de la República Argentina

Abstract: Antimicrobial resistance of Escherichia coli isolated from pigs in Argentina. Sixty-nine Escherichia coli isolates from healthy pigs or with clinical signs non-compatible with diarrhea caused by this microorganism, were studied. The purpose was to determine the resistance profile against antimicrobials frequently used in veterinary and human medicine. The agar diffusion method was used. High resistance percentages against antimicrobials used in swine farms such as ampicillin, streptomycin and tetracycline were observed, as well as against trimetoprim-sulfametoxazole and chloramphenicol, compounds that were stopped being used several years ago. Sixty two percent of isolates showed multidrug-resistance. The results obtained in this work corroborate the hypothesis that the phenotypic distribution of resistance and possibly that of its genetic determinants, are directly influenced by the antimicrobial treatments used.

Bacteriemia por enterobacterias en adultos en un hospital universitario: análisis de cinco años

Abstract: Resumen es: La bacteriemia sigue siendo una de las causas mas importantes de morbilidad y mortalidad en pacientes adultos, a pesar de los numerosos antimicrobianos h...

Exploring the use of natural antimicrobial agents and pulsed electric fields to control spoilage bacteria during a beer production process.

Abstract: Different natural antimicrobials affected viability of bacterial contaminants isolated at critical steps during a beer production process. In the presence of 1 mg/ml chitosan and 0.3 mg/ml hops, the viability of Escherichia coli in an all malt barley extract wort could be reduced to 0.7 and 0.1% respectively after 2 hour- incubation at 4 °C. The addition of 0.0002 mg/ml nisin, 0.1 mg/ml chitosan or 0.3 mg/ml hops, selectively inhibited growth of Pediococcus sp. in more than 10,000 times with respect to brewing yeast in a mixed culture. In the presence of 0.1mg ml chitosan in beer, no viable cells of the thermoresistant strain Bacillus megaterium were detected. Nisin, chitosan and hops increased microbiological stability during storage of a local commercial beer inoculated with Lactobacillus plantarum or Pediococcus sp. isolated from wort. Pulsed Electric Field (PEF) (8 kV/cm, 3 pulses) application enhanced antibacterial activity of nisin and hops but not that of chitosan. The results herein obtained suggest that the use of these antimicrobial compounds in isolation or in combination with PEF would be effective to control bacterial contamination during beer production and storage.

Tuberculosis transmission of predominant genotypes of Mycobacterium tuberculosis in northern suburbs of Buenos Aires city region.

Abstract: Resumen en: In 2003, the incidence of tuberculosis in Argentina showed an increase compared to 2002. The severe national crisis at the end of the 90s has probably st...

Prevalencia de anticuerpos antirrubéola y antiparvovirus B19 en embarazadas de la ciudad de Córdoba y en mujeres en edad fértil de la ciudad de Villa Mercedes, San Luis

Abstract: Resumen es: Se determino la prevalencia de anticuerpos contra virus rubeola en 100 muestras de suero de mujeres embarazadas que concurrian a chequeos de rutina en un...

Paracoccidioidomicosis asociada a otras patologías respiratorias en un hospital de Corrientes, Argentina

Abstract: Resumen es: Se realizo la busqueda sistematica de paracoccidioidomicosis (PCM) en un conjunto de pacientes que fueron atendidos en un hospital de la ciudad de Corrie...

Pathogenic Leptospira in the kidney of Didelphys albiventris (weasel)

Abstract: Se visualizan leptospiras en la luz de los túbulos contorneados renales mediante la técnica de Warthin-Starry; el tejido fue fijado en formol, incluido en parafina y cortado a 5 μ. Se logró el aislamiento a partir del riñón de la comadreja. La cepa aislada fue clasificada como Leptospira interrogans canicola. En la leptospirosis es muy importante el papel del hospedador de mantenimiento, el cual asegura la perpetuación del microorganismo en el medio. Entre los mamíferos silvestres, ratones, ratas, marsupiales, coipos, cuises, zorros, armadillos y animales poiquilotermos son responsables de mantener leptospiras en un determinado ambiente. Durante un brote, pueden estar involucradas varias especies animales domésticas y silvestres que viven en biocenosis. La transmisión tiene lugar por contacto directo con orina que contenga leptospiras.

Water quality in a lagoon in the southeast pampa region of Argentina.

Abstract: Resumen en: This work evaluates the chemical and bacteriological qualities of the recreational waters of the Sauce Grande lagoon (Argentina). Samples were taken betw...

Evaluación de la técnica de MSP-PCR para la caracterización molecular de aislamientos de Rhodotorula mucilaginosa provenientes de la Patagonia noroccidental

Abstract: The rapid identification of environmental or clinical yeast isolates is important for biodiversity studies and the detection of probable pathogens. Rhodotorula mucilaginosa is a ubiquitous and pigmented yeast capable of infecting immunocompromised patients. In this study, we evaluated the Micro/mini satellite-primed PCR (MSP-PCR) fingerprinting method for the characterization and identification of R. mucilaginosa isolates from natural environments in northwestern Patagonia. There were selected 110 putative R. mucilaginosa isolates from 200 environmental pigmented yeast isolates on the basis of phenotypic criteria. (GTG)5, (GAC)5 and M13 primers were initially evaluated in representative R. mucilaginosa isolates. (GTG)5 allowed a good grouping of these isolates and, at the same time, a good differentiation among closely related species, and thus was selected for subsequent studies. R. mucilaginosa isolates (87%) presented similar (> 60%) MSP-PCR profiles to those of the reference strain CBS 316T. The MSP-PCR technique was effective, both, for the characterization and identification of a large number of R. mucilaginosa environmental isolates as well as for the detection of polymorphisms within the species.

[Mycobacterium avium subsp. paratuberculosis in food and its relationship with Crohn's disease].

Abstract: Paratuberculosis or Johne's disease is a chronic enteritis of the cattle and other small ruminant animals caused by Mycobacterium avium subsp. paratuberculosis. In Argentina, the strains were characterized in beef and dairy cattle and deer in different genetic patterns by molecular tools. M. avium subsp. paratuberculosis has been linked in men to a chronic inflammation of the intestine, named Crohn's disease. There is clinical and experimental evidence to link M. avium subsp. paratuberculosis with Crohn's disease by PCR, positive bacteriological culture from mother milk, blood and affected tissues by in situ hybridization. The milk and sub-products might be one of the possible infection sources and it has been suggested that M. avium subsp. paratuberculosis could resist pasteurization. Several works showed that this mycobacteria could be present in retail milk of countries such as United Kingdom, USA, Czech Republic, and recently in Argentina. M. avium subsp. paratuberculosis was associated with different dairy products and water for human consumption. Therefore, it is possible that these food sources may have a role for transmission. New investigations should emphasize the role of contaminated food and water in human infection around the world and determine the possible zoonotic role of M. avium subsp. paratuberculosis.

Actividad antimicrobiana de mieles del sudeste de la provincia de Buenos Aires frente a Escherichia coli

Abstract: Antimicrobial activity of honey against Escherichia coli. This study assessed the susceptibility of Escherichia coli to the antimicrobial activity of honeys by different techniques. Honeys used were from the southeast region of Buenos Aires province. In order to evaluate antimicrobial activity against Escherichia coli ATCC 25922, solutions containing 0, 1, 5, 10, 25 and 50% (w/v) of honey were prepared. Liquid media (Mueller-Hinton and Mac Conkey broths) were used to assess the Minimal Inhibitory Concentration (MIC) by the serial dilution test. The minimal bactericidal concentration (MBC) was determined by counting on nutritive and Mac Conkey agar. In addition, for the evaluation of total antibacterial activity, the agar diffusion method was used. A reduction of microbial growth of 96% in Mueller-Hinton broth and of 90% in Mac Conkey broth by honey solutions containing 50% and 25% (w/v), was respectively observed. The bactericide action of honey in nutritive agar proved negative. The MBC value in Mac Conkey agar was 25% (w/v) of honey. The methods used for measuring the antibacterial activity in the present work were adequate to prove that honeys are active against E. coli at 25 and 50% (w/v) concentrations. The results obtained by the dilution method with MuellerHinton broth and the agar diffusion method were both concordant.

Mycobacterium avium subsp. paratuberculosis: presencia en los alimentos y su relación con la enfermedad de Crohn

Abstract: Resumen es: La paratuberculosis o enfermedad de Johne es una enteritis cronica producida por Mycobacterium avium subsp. paratuberculosis, que afecta a bovinos y a ot...

Tinea nigra palmaris: presentación de un caso clínico en la República Argentina

Abstract: A clinical case of a female patient with a black spot on the palm of her left hand is presented. The infection was due to a black fungus identified as Hortaea werneckii, the aetiological agent of tinea nigra palmaris. This infection can be easily diagnosed and it is important to establish the differential diagnosis from other skin pathologies. Normally, the treatment has a successful outcome. In this case, the patient was treated with econazole locally applied during one month, with complete remission of the lesions. In conclusion, the early diagnosis of this disease is very important since the mycology procedures are fast and non-invasive and cure is obtained with local treatment.

Diagnóstico de pseudotuberculosis en ovinos patagónicos

Abstract: Diagnosis of caseous lymphadenitis in sheep from Patagonia. Caseous lymphadenitis (CLA) is a chronic bacterial, infectious and contagious disease caused by Corynebacterium pseudotuberculosis. It affects sheep and results in abscesses of the lymph nodes in subcutaneous tissue, as well as in internal organs such as lungs, liver and kidneys. Differential diagnosis of the disease is based on the isolation and biochemical identification of the etiological agent. The purpose of this study was to characterize the bacteria isolated from typical CLA lesions in sheep from Patagonia, Argentina, at metabolic and genetic levels. Macroscopic observations show a fibrous membrane containing caseous necrotic tissue. Histopathological analysis shows an eosinophilic necrotic area surrounded by epitheloid cells and polymorphonuclear infiltration. Other analyses performed such as microscopic observations, in vitro culture, biochemical tests and 16s rDNA sequencing confirmed diagnosis of caseous lymphadenitis due to C. pseudotuberculosis.

Susceptibility trends of Bacteroides fragilis group isolates from Buenos Aires, Argentina.

Abstract: The aim of this study was to analyze the susceptibility trends to seven antibiotics of Bacteroides fragilis group isolates based on three survey studies perf...

Antimicrobial activity of honey the southeast of Buenos Aires Province against Escherichia coli

Abstract: This study assessed the susceptibility of Escherichia coli to the antimicrobial activity of honeys by different techniques. Honeys used were from the southeast region of Buenos Aires province. In order to evaluate antimicrobial activity against Escherichia coli ATCC 25922, solutions containing 0, 1, 5, 10, 25 and 50% (w/v) of honey were prepared. Liquid media (Mueller-Hinton and Mac Conkey broths) were used to assess the Minimal Inhibitory Concentration (MIC) by the serial dilution test. The minimal bactericidal concentration (MBC) was determined by counting on nutritive and Mac Conkey agar. In addition, for the evaluation of total antibacterial activity, the agar diffusion method was used. A reduction of microbial growth of 96% in Mueller-Hinton broth and of 90% in Mac Conkey broth by honey solutions containing 50% and 25% (w/v), was respectively observed. The bactericide action of honey in nutritive agar proved negative. The MBC value in Mac Conkey agar was 25% (w/v) of honey. The methods used for measuring the antibacterial activity in the present work were adequate to prove that honeys are active against E. coli at 25 and 50% (w/v) concentrations. The results obtained by the dilution method with Mueller-Hinton broth and the agar diffusion method were both concordant.

Intramammary infections during the periparturient period in Argentine dairy heifers

Abstract: Prevalence of intramammary infections at prepartum and postpartum in primigravid heifers from five dairy herds located in the central dairy area of Argentina was determined. Mammary secretion samples from 140 heifers (560 mammary quarters) were obtained 14 days prior to the expected calving day and within 7 days after parturition and subjected to bacteriological analysis. No clinical mastitis cases were detected during the study. The number of infected heifers in at least one mammary quarter at pre and postpartum was 87 (62.2%) and 53 (37.8%), respectively. The most prevalent mastitis pathogens at prepartum among samples yielding a positive bacteriological culture were coagulase-negative staphylococci (69.07%), Staphylococcus aureus (12.71%) and Streptococcus uberis (4.42%). A decrease on isolation frequency of coagulase-negative staphylococci (53.41%) and S. uberis (2.27%) was observed at postpartum, while that of S. aureus showed an increase (21.59%). Presence of intramammary infections appeared to be associated with some management conditions. These results highlighted the need to improve diagnosis and control measures in replacement heifers.

Características fenotípicas útiles para la identificación presuntiva de Candida guilliermondii

Abstract: Resumen es: En el medio CHROMagar Candida, Candida guilliermondii desarrollo una colonia de color rosado-purpura. En laminas de agar leche-tween 80 al 1%, presento a...

Diseño y construcción de vectores de transferencia para la obtención de virus vaccinia Ankara modificado (MVA) recombinantes

Abstract: Design and construction of transfer vectors in order to obtain recombinant modified vaccinia virus Ankara (MVA). Modified Vaccinia virus Ankara (MVA) constitutes a good candidate for the development of non-replicative expression viral vectors because it does not replicate in most of mammalian cells. It is essential, for the production of recombinant MVA, the availability of transfer vectors which allow the introduction of desired genes into non-essential regions for in vitro viral replication, by homologous recombination with the viral genome. In the present work, the transfer vectors named VT-MHA and VT-MTK were designed and obtained. They carried genomic regions corresponding to 1- 303 and 608-948 positions of the MVA165R gene and 1-244 and 325-534 of the MVA086R gene, respectively, which flank a multiple cloning site for the insertion of foreign genes. In these vectors, the cassettes for the expression of lac Z or uid A genes were cloned, and the activity of the marker enzymes b-galactosidase and b-glucuronidase was confirmed in situ. Furthermore, the vector named VT-MTK-GUS was used to obtain and isolate pure recombinant MVA, which carried and expressed the uid A gene. The results herein constitute the basic tools for establishing the methodology to obtain recombinant MVA with the purpose of locally developing non-replicative viral vectors as candidate vaccines.