Combinations of phage (MOI of 1) and 4 μg/ml of ciprofloxacin HCl (MIC of 5 μg/ml) (Santa-Cruz Biotechnology, Dallas, USA) were tested in triplicate against a growing culture of strain DPC6051 (8.1 ± 0.04 log cfu/ml), in 5 ml LB supplemented with 10 mM MgSO4, and incubated at 37°C for 24 h. Ciprofloxacin is an antibiotic of the fluoroquinolone class, that inhibits bacterial replication by acting on DNA gyrases.
A miniaturized enumeration method previously described [28 ] was performed to evaluate the frequency of antibiotic-resistant mutants after phage-antibiotic treatment. The threshold of detection was 20 cfu/ml.
A miniaturized enumeration method previously described [28 ] was performed to evaluate the frequency of antibiotic-resistant mutants after phage-antibiotic treatment. The threshold of detection was 20 cfu/ml.