Isolation and antibiotic susceptibility testing of rapidly-growing mycobacteria from grassland soils

0396950 - BC 2014 SK eng J - Journal Article
Kyselková, Martina - Chroňáková, Alica - Němec, Jan - Kotrbová, Lucie - Elhottová, Dana
Isolation and antibiotic susceptibility testing of rapidly-growing mycobacteria from grassland soils.
Journal of Microbiology, Biotechnology and Food Sciences. Roč. 3, č. 1 (2013), s. 76-80. ISSN 1338-5178
R&D Projects: GA ČR GAP504/10/2077; GA MŠMT LC06066; GA MŠMT(CZ) EE2.3.30.0032
Grant - others:GA JU(CZ) GAJU 04-142/2010/P
Institutional support: RVO:60077344
Keywords : mycobakterium isolation and cultivation * grassland soil * antibiotic resistance
Subject RIV: EE - Microbiology, Virology

Rapidly growing mycobacteria (RGM) are common soil saprophytes, but certain strains cause infections in human and animals. The infections due to RGM have been increasing in past decades and are often difficult to treat. The susceptibility to antibiotics is regularly evaluated in clinical isolates of RGM, but the data on soil RGM are missing. The objectives of this study was to isolate RGM from four grassland soils with different impact of manuring, and assess their resistance to antibiotics and the ability to grow at 37°C and 42°C. Since isolation of RGM from soil is a challenge, a conventional decontamination method (NaOH/malachite green/cycloheximide) and a recent method based on olive oil/SDS demulsification were compared. The olive oil/SDS method was less efficient, mainly because of the emulsion instability and plate overgrowing with other bacteria. Altogether, 44 isolates were obtained and 23 representatives of different RGM genotypes were screened. The number of isolates per soil decreased with increasing soil pH, consistently with previous findings that mycobacteria were more abundant in low pH soils. Most of the isolates belonged to the Mycobacterium fortuitum group. The majority of isolates was resistant to 2-4 antibiotics. Multiresistant strains occurred also in a control soil that has a long history without the exposure to antibiotic-containing manure. Seven isolates grew at 37°C, including the species M. septicum, M. fortuitum known for infections in humans. This study shows that multiresistant RGM close to known human pathogens occur in grassland soils regardless the soil history of manuring.
Permanent Link: http://hdl.handle.net/11104/0226334