The existence of steep oxygen gradients within the cystic fibrosis (CF)
airways mucus is well known, with zones ranging from aerobic to
completely anaerobic. Those environments, of heterogeneous
availabilities of oxygen, contribute for the proliferation of a
phylogenetically diverse ecosystem. This study aimed to inspect whether
CF-related bacteria - Staphylococcus aureus and Pseudomonas
aeruginosa and other emerging species Acinetobacter baumannii,
Dolosigranulum pigrum, Inquilinus limosus, Klebsiella pneumoniae and
Stenotrophomonas maltophilia are able to develop in vitro biofilms and
be tolerant towards ciprofloxacin, an in-use antibiotic in acute CF
infections. Single biofilms were formed in vitro, under aerobic and
anaerobic environments, and further evaluated in terms of biomass and
CFU counting. The antibiotic resistance profiles were analysed by
constructing time-kill-curves.All species were able to growth under
environments with distinct oxygen availability, demonstrating a great
biofilm-forming ability highlighted by higher amount of biofilm mass,
particularly under aerobic atmospheres.Biofilm time-kill curves showed
augmented antibiotic tolerance of the bacteria, which was independent of
the oxygen availability, except for D. pigrum where total eradication of
biofilm-cells was noticed. Data highlighted that CF-related bacteria could
persist under atmospheres with restricted oxygen availability, and form
biofilms resilient to ciprofloxacin. Therefore, a more detailed knowledge
about the effect of CF environments on the ability of the bacteria to
proliferate and resist to antibiotics might be crucial for the success of CF
infection treatment
