TY - JOUR

T1 - Biofilms of mycobacterium abscessus complex can be sensitized to antibiotics by disaggregation and oxygenation

AU - Kolpen, Mette

AU - Jensen, Peter Østrup

AU - Qvist, Tavs

AU - Kragh, Kasper Norskov

AU - Ravnholt, Cecillie

AU - Fritz, Blaine Gabriel

AU - Johansen, Ulla Rydahl

AU - Bjarnsholt, Thomas

AU - Hoiby, Niels

PY - 2020

Y1 - 2020

N2 - Pulmonary infection with the multidrug-resistant Mycobacterium abscessus complex (MABSC) is difficult to treat in individuals with cystic fibrosis (CF). MABSC grows as biofilm aggregates in CF patient lungs, which are known to have anaerobic niches. How aggregation and anoxic conditions affect antibiotic tolerance is not well understood. We sought to determine whether disaggregation and oxygen availability sensitize MABSC isolates to recommended antibiotics. We tested the susceptibilities of 33 isolates from 22 CF patients with MABSC infection and a reference strain to the following antibiotics: amikacin, azithromycin, cefoxitin, ciprofloxacin, clarithromycin, imipenem, kanamycin, linezolid, moxifloxacin, rifampin, tigecycline, and sulfamethoxazole-trimethoprim. Isolates were grown in Mueller-Hinton broth with and without the disaggregating detergent Tween 80 (5%). Time-kill curves at days 1 and 3 were generated for oxic and anoxic amikacin treatment in 4-fold dilutions ranging from 2 to 512mg liter1. Scanning electron microscopy was used to visualize the aggregation patterns, while confocal laser scanning microscopy and microrespirometry were used to visualize biofilm growth patterns. Disruption of MABSC aggregates increased susceptibility to amikacin, tigecycline, kanamycin, azithromycin, imipenem, cefoxitin, and clarithromycin (P<0.05, n29 to 31). Oxygenation enhanced the killing of disaggregated MABSC isolates by amikacin (P<0.05) by 1 to 6 log units when 2 to 512mg liter1 of amikacin was used. This study explains why current drug susceptibility testing results correlate poorly with treatment outcomes. The conditions achieved by oxic culturing of planktonic isolates in vitro do not resemble the hypoxic conditions in CF patient lungs. Biofilm disruption and increased O2 availability during antibiotic therapy may be new therapeutic strategies for chronic MABSC infection.

AB - Pulmonary infection with the multidrug-resistant Mycobacterium abscessus complex (MABSC) is difficult to treat in individuals with cystic fibrosis (CF). MABSC grows as biofilm aggregates in CF patient lungs, which are known to have anaerobic niches. How aggregation and anoxic conditions affect antibiotic tolerance is not well understood. We sought to determine whether disaggregation and oxygen availability sensitize MABSC isolates to recommended antibiotics. We tested the susceptibilities of 33 isolates from 22 CF patients with MABSC infection and a reference strain to the following antibiotics: amikacin, azithromycin, cefoxitin, ciprofloxacin, clarithromycin, imipenem, kanamycin, linezolid, moxifloxacin, rifampin, tigecycline, and sulfamethoxazole-trimethoprim. Isolates were grown in Mueller-Hinton broth with and without the disaggregating detergent Tween 80 (5%). Time-kill curves at days 1 and 3 were generated for oxic and anoxic amikacin treatment in 4-fold dilutions ranging from 2 to 512mg liter1. Scanning electron microscopy was used to visualize the aggregation patterns, while confocal laser scanning microscopy and microrespirometry were used to visualize biofilm growth patterns. Disruption of MABSC aggregates increased susceptibility to amikacin, tigecycline, kanamycin, azithromycin, imipenem, cefoxitin, and clarithromycin (P<0.05, n29 to 31). Oxygenation enhanced the killing of disaggregated MABSC isolates by amikacin (P<0.05) by 1 to 6 log units when 2 to 512mg liter1 of amikacin was used. This study explains why current drug susceptibility testing results correlate poorly with treatment outcomes. The conditions achieved by oxic culturing of planktonic isolates in vitro do not resemble the hypoxic conditions in CF patient lungs. Biofilm disruption and increased O2 availability during antibiotic therapy may be new therapeutic strategies for chronic MABSC infection.

KW - Antimicrobial resistance

KW - Biofilm

KW - Cystic fibrosis

KW - Mycobacterium abscessus complex

KW - Oxygenation

U2 - 10.1128/AAC.01212-19

DO - 10.1128/AAC.01212-19

M3 - Journal article

C2 - 31740557

AN - SCOPUS:85078567607

VL - 64

JO - Antimicrobial Agents and Chemotherapy

JF - Antimicrobial Agents and Chemotherapy

SN - 0066-4804

IS - 2

M1 - e01212

ER -