TABLE 2

Diversity of mutants and their biocide and antibiotic susceptibility

Species and biocide phenotypeaPreconditioning agentbBiocide MIC (mg/liter)Antibiotic MIC (mg/liter)cMutant designationdNo. of CFU by plateeNo. of mutants
TRIBKCCHXAMPCAZCIPERYGENCLOTET
E. coli
    Parental strain HEC300.06168≥2560.250.023161–1.563
    TRIrTRI4162≥2560.130.032160.7533Ec_TRI/TRI223
CIP1328≥2560.750.75161120.75Ec_CIP/CIP7
BKC0.25168≥2560.50.032161.54–123Ec_BKC/BKC21
    TRIr CHXsNE1164≥2560.380.023161–1.562Ec_NE/TRI1UC1
K. pneumoniae
    Parental strain 39.110.51632320.380.04716123
    TRIrAMP23264640.750.0941611284Kpn_AMP/TRI2716
NE232641280.50.5161>25612Kpn_NE/CIP126
TRI23264≥2560.50.5161.5>2568Kpn_TRI/CIP177
CHX23264≥2560.380.38320.75>2568Kpn_CHX/CIP59
BKC23264≥25610.38960.7564>128Kpn_BKC/CIP53
SHC23264128–1920.750.532–481.5>25616–24Kpn_SHC/CIP31
NE23232320.50.38161>2564Kpn_NE/TRI1UC
TRI23232640.50.381211286Kpn_TRI/TRI2272
BKC23232480.50.381211284Kpn_BKC/TRI212
CHX23232320.50.5161>2564Kpn_CHX/TRI26
CIP23232320.380.5321>25624–32Kpn_CIP/TRI220
TRI23232≥2560.380.5160.5>25616–24Kpn_TRI/BKC1UC
BKC23232≥2561.50.38160.519232Kpn_BKC/BKC1UC
CIP23232≥2561.50.75>2560.199612Kpn_CIP/BKC211
AMP23232≥2560.50.5160.5>2568Kpn_AMP/CIP152
CIP232321920.50.38161>25612Kpn_NE/CIP126
    TRIhsNE0.12832480.250.094161.532Kpn_NE/CHX232
CIP0.121616320.25–0.380.09416141.5Kpn_CIP/CHX2UC
  • a TRI, triclosan; CHX, chlorhexidine.

  • b CIP, ciprofloxacin; BKC, benzalkonium chloride; NE, no exposure; AMP, ampicillin; SHC, sodium hypochlorite.

  • c CAZ, ceftazidime; ERY, erythromycin; GEN, gentamicin; CLO, chloramphenicol; TET, tetracycline.

  • d When the selecting agent was TRI, the numbers in the nomenclature of mutants refer to the concentrations of the compounds in the plates as follows: 1 = 1 mg/liter and 2 = 1.5 mg/liter. When the selecting agent was CHX, the concentration in the plate was as follows: 1 = 64 mg/liter or 2 = 128 mg/liter. In the case of BKC, the numbers 1 to 3 refer to the concentrations in plates as follows: 1 = 32 mg/liter, 2 = 64 mg/liter, and 3 = 128 mg/liter. The concentration of CIP was 0.12 mg/liter in all plates.

  • e UC, uncountable.