Resumo

Introduction. Our group isolated six mycobacteriophages from composting material from Fundação Parque Zoológico de São Paulo (FPZSP), using Mycobacterium smegmatis mc2155 as the receptor strain. Little is known about other possible hosts for these mycobacteriophages. Objectives. To verify if the mycobacteriophages isolated from compost at FPZSP are capable of infecting other rapidly-growing mycobacteria. Material and Methods. M. abscessus type strain ATCC 19977 and M. abcessus subsp. bolletii INCQS 00594 were used. INCQS 00594 is the reference strain from an outbreak of surgical-site infections that occurred between 2004 and 2008 in Brazil. Cultures in Middlebrook 7H9 medium, supplemented with 10% OADC (oleic acid, albumin, dextrose and catalase) and CaCl2 1mM, were incubated at 37°C under agitation. Bacteriophages were propagated in M. smegmatis mc2155 by the overlay method with 0.35% agar and stored at 4°C in phage buffer. To test the infection ability of the phages, 500 μL of each mycobacterium culture at O.D600~1.0 was combined with approximately 105 phage particles and 2.5 ml of MBTA (7H9-OADC with 0.7% agar). This mixture was poured on Middlebrook 7H10 agar containing 10% OADC and the plates were incubated overnight at 37°C. The presence of lysis plaques was observed after the incubation period. Results. The results obtained with M. abscessus ATCC 19977 were similar to those obtained with M. smegmatis mc2155, i.e. all phages formed a similar number of lysis plaques. Four of the six phages infected the clinical strain INCQS 00594, with a 10-fold lower number of plaques per plate. Conclusions. The clinical strain that caused the surgical outbreak in Brazil was less susceptible to infection by the phages isolated from compost than the M. abscessus reference strain and M. smegmatis.