Oxygen restriction generates difficult-to-culture p. Aeruginosa

TY - JOUR

T1 - Oxygen restriction generates difficult-to-culture p. Aeruginosa

AU - Kvich, Lasse

AU - Fritz, Blaine

AU - Crone, Stephanie

AU - Kragh, Kasper N.

AU - Kolpen, Mette

AU - Sønderholm, Majken

AU - Andersson, Mikael

AU - Koch, Anders

AU - Jensen, Peter

AU - Bjarnsholt, Thomas

PY - 2019

Y1 - 2019

N2 - Induction of a non-culturable state has been demonstrated for many bacteria, e.g., Escherichia coli and various Vibrio spp. In a clinical perspective, the lack of growth due to these non-culturable bacteria can have major consequences for the treatment of patients. Here, we show how anoxic conditioning (restriction of molecular oxygen, O2 ) generates difficult-to-culture (DTC) bacteria during biofilm growth. A significant subpopulation of Pseudomonas aeruginosa entered a DTC state after anoxic conditioning, ranging from 5 to 90% of the total culturable population, in both planktonic and biofilm models. Anoxic conditioning also generated DTC subpopulations of Staphylococcus aureus and Staphylococcus epidermidis (89 and 42% of the total culturable population, respectively). Growth of the DTC populations were achieved by substituting O2 with 10 mM NO3− as an alternative electron acceptor for anaerobic respiration or, in the case of P. aeruginosa, by adding sodium pyruvate or catalase as scavengers against reactive oxygen species (ROS) during aerobic respiration. An increase in normoxic plating due to addition of catalase suggests the molecule hydrogen peroxide as a possible mechanism for induction of DTC P. aeruginosa. Anoxic conditioning also generated a true viable but non-culturable (VBNC) population of P. aeruginosa that was not resurrected by substituting O2 with NO3− during anaerobic respiration. These results demonstrate that habituation to an anoxic micro-environment could complicate diagnostic culturing of bacteria, especially in the case of chronic infections where oxygen is restricted due to the host immune response.

AB - Induction of a non-culturable state has been demonstrated for many bacteria, e.g., Escherichia coli and various Vibrio spp. In a clinical perspective, the lack of growth due to these non-culturable bacteria can have major consequences for the treatment of patients. Here, we show how anoxic conditioning (restriction of molecular oxygen, O2 ) generates difficult-to-culture (DTC) bacteria during biofilm growth. A significant subpopulation of Pseudomonas aeruginosa entered a DTC state after anoxic conditioning, ranging from 5 to 90% of the total culturable population, in both planktonic and biofilm models. Anoxic conditioning also generated DTC subpopulations of Staphylococcus aureus and Staphylococcus epidermidis (89 and 42% of the total culturable population, respectively). Growth of the DTC populations were achieved by substituting O2 with 10 mM NO3− as an alternative electron acceptor for anaerobic respiration or, in the case of P. aeruginosa, by adding sodium pyruvate or catalase as scavengers against reactive oxygen species (ROS) during aerobic respiration. An increase in normoxic plating due to addition of catalase suggests the molecule hydrogen peroxide as a possible mechanism for induction of DTC P. aeruginosa. Anoxic conditioning also generated a true viable but non-culturable (VBNC) population of P. aeruginosa that was not resurrected by substituting O2 with NO3− during anaerobic respiration. These results demonstrate that habituation to an anoxic micro-environment could complicate diagnostic culturing of bacteria, especially in the case of chronic infections where oxygen is restricted due to the host immune response.

KW - Aeruginosa

KW - Anoxia

KW - Aureus

KW - Biofilm

KW - Difficult-to-culture

KW - Epidermidis

KW - P

KW - Reactive oxygen species

KW - S

KW - Viable but non-culturable

U2 - 10.3389/fmicb.2019.01992

DO - 10.3389/fmicb.2019.01992

M3 - Journal article

C2 - 31555231

AN - SCOPUS:85071924837

SN - 1664-302X

VL - 10

JO - Frontiers in Microbiology

JF - Frontiers in Microbiology

IS - AUG

M1 - 1992

ER -