Characterization of a Coliphage AS1 isolated from sewage effluent in Pakistan / Caracterização de um colifago AS1 isolado de efluente de esgoto no Paquistão

The emergence of multi-drug resistant (MDR) bacterial strains, which are posing a global health threat has developed the interest of scientists to use bacteriophages instead of conventional antibiotics therapy. In light of an increased interest in the use of phage as a bacterial control agent, the study aimed to isolate and characterize lytic phages from sewage effluent. During the current study, bacteriophage AS1 was isolated from sewage effluent against E.coli S2. The lytic activity of phageAS1 was limited to E.coli S2 strain showing monovalent behavior. The calculated phage titer was 3.5×109 pfu/ml. PhageAS1 was stable at a wide range of pH and temperature. The maximum stability was recorded at 37ºC and pH 7.0, while showing its normal lytic activity at temperature 60ºC and from pH 5.0 to 11.0 respectively. At temperature 70ºC, phage activity was somewhat reduced whereas, further increase in temperature and decrease or increase in pH completely inactivated the phage. From the current study, it was concluded that waste water is a best source for finding bacteriophages against multi-drug resistant bacterial strains and can be used as bacterial control agent.

O surgimento de cepas bacterianas multirresistentes (MDR), que representam uma ameaça global à saúde, desenvolveu o interesse dos cientistas em usar bacteriófagos em vez da terapia convencional com antibióticos. Diante do crescente interesse no uso de fago como agente de controle bacteriano, o estudo visou isolar e caracterizar fagos líticos de efluente de esgoto. Durante o estudo atual, o bacteriófago AS1 foi isolado de efluente de esgoto contra E. coli S2. A atividade lítica de phageAS1 foi limitada à cepa E. coli S2, apresentando comportamento monovalente. O título de fago calculado foi de 3,5 x 109 ufp/ml. PhageAS1 foi estável em uma ampla faixa de pH e temperatura. A estabilidade máxima foi registrada a 37ºC e pH 7,0, enquanto mostrou atividade lítica normal em temperatura de 60ºC e pH 5,0 a 11,0, respectivamente. Na temperatura de 70ºC, a atividade do fago foi um pouco reduzida, enquanto o aumento adicional da temperatura e a diminuição ou aumento do pH inativaram completamente o fago. Com base no estudo atual, concluiu-se que a água residual é a melhor fonte para encontrar bacteriófagos contra cepas bacterianas multirresistentes e pode ser usada como agente de controle bacteriano.

Mycobacteriophages as versatile tools for genetic manipulation of mycobacteria and development of simple methods for diagnosis of mycobacterial diseases / Micobacteriófagos como herramientas versátiles para la manipulación genética y el desarrollo de métodos simples para el diagnóstico de enfermedades micobacterianas

Tuberculosis, caused by Mycobacterium tuberculosis, is responsible for over two million deaths per year worldwide. Due to its long doubling time (18 h), the microbiological detection of M. tuberculosis by conventional methods takes up to one month, unless the number of bacilli in the biological sample is high enough. Thus, drug resistance assessment requires at least one month for obtaining the primary culture and another month to determine its susceptibility to antimycobacterial drugs. Moreover, for a long time, the lack of genetic tools for mycobacteria has been a barrier for undertaking studies aimed at understanding the mechanisms of drug resistance and drug target identification, being all these topics of utmost importance considering the increase in the number of drug-resistant clones and the few therapeutic options available. Mycobacteriophages are promising as a novel source of genetic elements for mycobacteria manipulation, as well as for the development of versatile, simple, fast and cheap methods for drug resistance assessment of M. tuberculosis clinical isolates. We herein describe the background related to the use of mycobacteriophages, with emphasis placed on their utilization for drug resistance analysis in our country.

La tuberculosis, enfermedad causada por el bacilo Mycobacterium tuberculosis, es responsable de más de dos millones de muertes anuales en el mundo. Debido a su largo tiempo de duplicación (18 h), la detección bacteriológica de M. tuberculosis por métodos convencionales necesita de un mes o aun más, a menos que el número de bacilos en la muestra clínica sea suficientemente alto. Por consiguiente, se necesita un mínimo de dos meses para determinar la resistencia de este microorganismo a las drogas antituberculosas: uno para obtener el cultivo primario y otro para ensayar la sensibilidad frente a aquellas. La falta de herramientas para la manipulación genética de micobacterias ha dificultado la identificación de los blancos de acción de las drogas y el estudio de los mecanismos de resistencia a éstas, tópicos de la mayor relevancia dado el aumento mundial del número de aislamientos clínicos multirresistentes y las pocas opciones terapéuticas disponibles. Los micobacteriófagos son considerados nuevas herramientas para la manipulación de las micobacterias, así como para el desarrollo de métodos simples, rápidos y económicos para determinar la sensibilidad a drogas de los aislamientos clínicos de M. tuberculosis. En esta revisión se describen los antecedentes del uso de micobacteriófagos con énfasis en su utilización para el análisis de resistencia a drogas antituberculosas en nuestro país.

Antimicrobial susceptibility patterns and phage types of Salmonella typhi from Vietnam.

A retrospective study of the patterns of antimicrobial susceptibility and phage types of 111 Salmonella typhi strains isolated in 1996 from Vietnam was carried out. The strains were tested for susceptibility to chloramphenicol, ampicillin, tetracycline, trimethoprim-sulfamethoxazole, nalidixic acid, ceftazidime, ceftriaxone and ciprofloxacin. Simultaneous resistance to chloramphenicol, ampicillin, tetracycline and trimethoprim-sulfamethoxazole were present in 84 strains (75.7%). Nalidixic acid resistance was only observed in 2 multidrug-resistant strains (1.8%). Twenty-one strains (18.9%) were completely susceptible to all drugs tested. All 111 strains were susceptible to ceftazidime, ceftriaxone and cipropfloxacin. The MIC values for chloramphenicol, ampicillin and trimethoprim-sulfamethoxazole corresponded with the results by disk diffusion method. On Vi phage-typing, 5 different phage types (28, A, D1, E1 and M1) were found in 12 strains (10.8%). However, most S. typhi strains were indistinguishable by this typing technique because they were degraded Vi-positive or untypeable Vi-positive strains (35.1% and 54.1%, respectively). There were no correlations between antimicrobial resistance patterns and phage types in the tested S. typhi strains in this study.

A study of phage based diagnostic technique for tuberculosis.

BACKGROUND: Tuberculosis (TB) is a leading infectious disease in India.Diagnosis of TB has always been a problem due to slow rate of growth of Mycobacterium tuberculosis. In this study we have compared the conventional tools for diagnosis of TB with the new Fast Plaque TB TM MATERIAL AND METHODS: Two hundred and twelve clinically suspected cases of TB were enrolled for the study. Three consecutive early morning sputum samples were collected from each patient. Sputum smears were examined after staining with ZN stain and the sputum samples were later subjected to culture and phage assay. RESULTS: It was seen from the study that out of the total 212 cases, 106 were phage positive and 106 were phage negative. Sensitivity of the phage test with respect to AFB smear is 94.34% and specificity of the phage test is 93.88%. A total of 120 specimens grew on LJ media, of which 112 were Mycobacterium tuberculosis, 2 were Mycobacterium Kansasii, 4 were Mycobacterium avium complex and 2 grew Mycobacteriumfortuitum group. Out of these 120 specimens which grew on LJ, 104 were also positive for phage assay. All the 8 Non-Tubercular Mycobacteria were negative by the Fast Plaque Assay. Out of the 92 which were negative on LJ, 2 were positive by phage assay. Sensitivity and specificity of phage assay with respect to growth on LJ was 92.86% and 97.83% respectively. CONCLUSION: The study showed that phage assay is a rapid, reliable and cost effective method in diagnosing pulmonary tuberculosis from clinical samples.

Antimicrobial susceptibility, phage types, and pulsetypes of Salmonella Typhimurium, in São Paulo, Brazil

A total of 283 Salmonella Typhimurium strains isolated from cases of human infections and non human sources, were examined for antimicrobial susceptibilityand the incidence of resistance was 38 percent and multiple resistance (to three or more antimicrobials) was 15 percent. All 43 multidrug-resistant strains (MDR) and 13 susceptible ones were characterized by phage typing and pulsed- field gel electrophoresis (PFGE). The strains encompassed 14 definitive phage types (DT), three were untypable (UT), and 18 atypicals or reaction does not conform (RDNC), which belonged to 21 PFGE patterns, A1-A21. The predominant phage types were DT49, DT193, and RDNC and two strains belonging to DT 104 and 104b were also identified. The most commum PFGE patterns were A1 and A8. Analysis by PFGE and phage typing demonstrated that the most of the MDR were multiclonal and association among multiresistance, phage typing, and PFGE patterns was not so significant.

Bacteriophage typing and antibiotic sensitivity pattern of Staphylococcus aureus from clinical specimen in and around Solapur (South Maharashtra).

Two hundred and eighty nine strains of Staphylococcus aureus isolated from pus and wound swabs (149), blood (36), urine (28), sputum (14), stool (12), throat swab (9) and CSF (4) were subjected for bacteriophage typing and antibiotic susceptibility pattern. 113 (39.11%) strains were typable. Among the typable strains, 16 (5.53%) belonged to phage group I, 33 (11.41%) strains belonged to phages group II, 38 (13.14%) belonged to phage group III, 26 (8.99%) strains belonged to the phages which have not been allocated to any group (Miscellaneous group) 176 (60.89%) strains were untypable. Only one (0.34%) strain was sensitive to all the drugs tested. Almost all the isolates were resistant to Ampicillin and Tobramycin (99.3% each). 286 (98.96%) strains were found to be resistant to Penicillin and Erythromycin followed by Kanamycin 272 (94.11%) and Gentamicin 263 (91.3%). 113 (39.1%) strains were Methicillin resistant Staphylococcus aureus (MRSA). All MRSA strains were resistant to all drugs tested except vancomycin. Resistance to most of the commonly used antimicrobial agents indicates a need to replace these drugs with other agents and maintenance of surveillance to detect changing patterns of resistance.

Isolation of Vibrio cholerae 0139 phages to develop a phage typing scheme.

Five V. cholerae 0139 phages isolated from different parts of India have been used for phage typing study. A strain isolated from Nagpur city (NPR-4) was used as the host for phage propagation. All but one of the 260 strains of V. cholerae 0139 were found to be typeable and could be clustered into 8 distinct phage types as revealed by lytic patterns. Phage type 1 was the predominant type (61.15%) followed by type 2 (18.46%). The strains isolated from Madras exhibited 7 out of 8 phage types. These newly isolated phages could be adopted for phage typing of V. cholerae 0139 strains as an epidemiological tool.

Validity of new phage typing scheme against Vibrio cholerae 01 biotype ElTor strains.

A total of 538 strains of V. cholerae 01 biotype ElTor were phage typed by the conventional Basu and Mukerjee and also the new typing scheme developed at the National Institute of Cholera and Enteric Diseases, Calcutta. The strains could be clustered into seven types by the new scheme as against only two by the conventional method. The results provide conclusive evidence on the validity of the new scheme for phage typing of V. cholerae strains.

Bacteriophage typing of Vibrio fluvialis.

Six stable bacteriophages of Vibrio fluvialis were isolated from 44 surface water specimens collected in Thailand and Japan. Twelve different phages types were found among 109 V. fluvialis isolated from feces of diarrheal patients and the environment. Seventy-three percent (80/109) of these 109 isolates were typable with these phages. One phage type, designated as A (1) was predominant and accounted for 43% of the V. fluvialis examined. The six bacteriophages used in this typing scheme were stable for at least during a three-month storage at 4 degrees C. This proposed bacteriophage typing scheme may be of valuable aid in tracing sources and routes of infection in outbreaks of V. fluvialis infection in man.

Fagotipaje de Mycobacterium tuberculosis por la técnica de la doble capa (overlay). Estudio preliminar / Phagotyping of Mycobacterium tuberculosis by the double layer technique. A preliminary study

Se clasificaron 150 cepas de Mycobacterium tuberculosis mediante la técnica de fagotipaje, utilizando el método de la doble capa descrito por Adams y con las modificaciones realizadas por Jones. Se estudió la eficiencia de este método en comparación con el método preconizado por Redmond y Ward, empleando tradicionalmente para el tipaje de micobacteria. Los resultados preliminares obtenidos han permitido corroborar sus ventajas. Se reportó una coincidencia del 96 por ciento con respecto al tradicional

Evaluación de antisueros grupo y tipo específicos para la tipificación en México de infecciones estreptocóccicas / Evaluation of group and type specific antisera used on the typification of streptococcal diseases in Mexico

La fiebre reumática es una enfermedad endémica en México; cuando se hace un buen diagnóstico, tratamiento y prevención de la infección estreptocóccica se puede tener información adecuada en relación con los tipo de Streptococcus pyogenes prevalentes y su distribución. Se estudiaron 29 cepas de Streptococcus, aislados de exudado faríngeo de preescolares y de estudiantes cuya edad fluctuaba entre 16 y 20 años. Diez cepas fueron del grupo A, cuatro del grupo B, tres del grupo C y cuatro del grupo G. El antígeno T11, 12 se observó en cuatro cepas; otros fueron: 2 T1, 2 T12 y 1 T23. Sólo se identificó el antígeno en tres cepas correspondiendo al tipo M11 y M12 en dos de ellos; el resto no fue tipificable. Las cepas de grupo B, fueron del tipo Ia, Ic y dos del tipo III. Siete sueros preparados en México en conejos se evaluaron mediante reacción de precipitación, inmunodifusión y prueba de poder bactericida; cinco de éstos fueron aceptables pero presentaron un alto grado de reacciones cruzadas; solamente dos de los sueros tenían poder bactericida y dos fueron tipo específicos. Es necesario tipificar las cepas de Streptococcus en estudios epidemiológicos y contar con información en relación a su distribución y cambios en los tipo, siendo indispensable mejorar los métodos para preparar sueros tipo específicos y emplear la tipificación de T en forma paralela a la tipificación de M de las cepas aisladas en México

Clasificación del mycobacterium tuberculosis por marcadores fagotípicos en la provincia Ciudad de la Habana / Classification of mycobacterium tuberculosis by phage-type markers in Havana City Province

Se estudiaron 50 cepas de Mycobacterium tuberculosis aisladas de pacientes de la provincia Ciudad de la Habana por técnicas de fagotipaje, con la utilización de un juego de 11 fagos específicos para M. tuberculosis. Del total de cepas estudiadas, el 50 corresponde al tipo Ao, el 44 al tipo A1, el 2 al tipo A2 y el 4 al tipo A3, no se informan ninguno de lo tipos restantes del A, ni los tipos B y C

Estudio comparativo de Mycobacterium cubense por técnicas de fagotipaje / Comparative study of Mycobacterium cubense by phagotyping techniques

Se realiza un estudio comparado de M. cubense con otras especies micobacterianas del grupo II de Runyon (M. scrophulaceum, cepas Bridge, Gause y Lunnig. M. gordonal y M. szulgae) a través de las técnicas de fagotipaje en micobacterias. Se presentan los patrones de lisis de las cepas estudiadas y se registran valores que permiten la diferenciación de M. cubense del resto estudiado