The use of BHI to study our SCV strains as well as in the experiments

involving quantification of SCVs is validated in the Additional file 1. Pseudomonas aeruginosa PAO1 [61], PA14 [62], the PA14-derived pqsA and pqsL mutants [44, 46] and Escherichia coli K12 were grown in trypticase soy broth (TSB) (BD, ON, Canada). Table 1 Bacterial strains used in this study Strains Relevant characteristics Auxotrophism References S. aureus strains       ATCC 29213 Laboratory strain, normal – - Newman ATCC 25904 Laboratory strain, normal – - Newbould ATCC 29740 Laboratory strain, normal – - NewbouldΔsigB Newbould ΔsigB::emrA; ErmR – [15] NewbouldhemB Newbould hemB::ermA; ErmR Hemin [17] CF03-S SCV selleck chemicals llc strain isolated from a CF patient Menadione [15] CF03-L Normal BVD-523 cost strain co-isolated with CF03-S – This study CF07-S SCV strain isolated from a CF patient Menadione [15] CF07-L Normal strain co-isolated with CF07-S – This study CF1D-S SCV strain isolated from a CF patient Unknown This study CF1A-L Normal strain co-isolated with CF1D-S – This study P. aeruginosa strains       PAO1 Laboratory strain – [61] PA14 Clinical strain, RifR – [62] pqsA PA14 pqsA::TnphoA; RifR, KmR – [44] pqsL PA14 ΔpqsL; RifR – [46] E. coli strains       K12 Laboratory strain – - Multiple-locus variable-number of tandem repeat analysis (MVLA) of strains co-isolated from XAV-939 cell line CF patients The relatedness of each of the co-isolated strains

within the pairs CF03-L/CF03-S, CF07-L/CF07-S and CF1A-L/CF1D-S was confirmed by MVLA as described by Sabat et al.

[63]. The strains of each pair had identical MVLA patterns. Growth curves S. aureus overnight cultures were used at an A 595 nm of 0.1 to inoculate BHI broths supplemented or not with 10 μg/ml of HQNO (Axxora, CA, USA). Cultures were then incubated at 35°C/225 RPM and samples were taken at different time points for determination of CFU by spreading filipin 10-fold dilutions on trypticase soy agar (TSA) plates (BD, ON, Canada). Plates were incubated at 35°C for 24 and 48 h for normal and SCV strains, respectively. For the growth curves of P. aeruginosa PA14 and the pqsA and pqsL mutants, overnight cultures were used to inoculate TSB. Cultures were then incubated at 35°C/225 RPM and samples were taken at specified time points in order to evaluate their turbidity at A 595 nm. Quantification of SCVs We have quantified SCVs by taking advantage of their reduced susceptibility to aminoglycosides as described elsewhere with few modifications [20, 64, 65]. A 1:100 dilution of overnight broth cultures was used to inoculate BHI broths supplemented or not with 10 μg/ml of HQNO. Cultures were incubated 18 h and then adjusted to an A 595 nm of 2.0 in PBS at 4°C. Determination of SCV CFUs was done by serial dilution plating. SCV counts were obtained by plating on TSA containing gentamicin (Sigma-Aldrich, ON, Canada) at 4 μg/ml followed by an incubation of 48 h at 35°C.