Biofilm-associatedMycobacterium abscessuscells have altered antibiotic tolerance and surface glycolipids in Artificial Cystic Fibrosis Sputum Media

Abstract

8Mycobacterium abscessus (Mab) is a biofilm-forming, multi-drug resistant, non-9 tuberculous mycobacterial (NTM) pathogen increasingly found in Cystic Fibrosis 10 patients. Antibiotic treatment for these infections is often unsuccessful, partly due to 11 Mab's high intrinsic antibiotic resistance. It is not clear whether antibiotic tolerance 12 caused by biofilm formation also contributes to poor treatment outcomes. We studied 13 the surface glycolipids and antibiotic tolerance of Mab biofilms grown in Artificial Cystic 14 Fibrosis Sputum (ACFS) media in order to determine how they are affected 15 by nutrient conditions that mimic infection. We found that Mab displays more of the 16 virulence lipid trehalose dimycolate when grown in ACFS compared to standard lab 17 media. In ACFS media, biofilm-associated cells are more antibiotic tolerant than 18 planktonic cells in the same well. This contrasts with standard lab medias, where biofilm 19 and planktonic cells are both highly antibiotic tolerant. These results indicate that Mab 20 cell physiology in biofilms depends on environmental factors, and that nutrient 21 conditions found within Cystic Fibrosis infections could contribute to both increased 22 virulence and antibiotic tolerance.23 Concentration(μg/mL) Concentration(μg/mL) Concentration(μg/mL) Concentration(μg/mL) Concentration(μg/mL) Concentration(μg/mL) Concentration(μg/mL) Concentration(μg/mL) Amikacin Cefoxitin Clarithromycin Amikacin Cefoxitin Clarithromycin

InMycobacterium abscessus, the stringent factor Rel regulates metabolism, but is not the only (p)ppGpp synthase

“…Mab is an opportunistic pathogen that both lives in the environment, and causes skin and respiratory infections which are increasingly prevalent in Cystic Fibrosis patients (6). Mab infections are especially difficult to treat because this species is naturally resistant to many antibiotics (7), and highly tolerant under stress to almost all antibiotics tested (8,9). One proposed strategy to help treat such antibioticrecalcitrant infections is to inhibit the regulatory systems, like the stringent response, that promote antibiotic tolerance (10)(11)(12)(13).…”