Dataset Information

Effect of High-Dose Antimicrobials on Biofilm Growth of Achromobacter Species Isolated from Cystic Fibrosis Patients.

ABSTRACT: MICs and biofilm inhibitory concentrations (BICs) were measured for 68 cystic fibrosis (CF) Achromobacter isolates for amikacin, aztreonam, colistin, levofloxacin, and tobramycin. With the exception of colistin and levofloxacin, the remaining antibiotics had MIC90s, BICs at which 50% of the isolates were susceptible (BIC50s), and BICs at which 90% of the isolates were susceptible (BIC90s) equal to or above the highest concentrations tested. In a biofilm model, tobramycin was able to significantly increase killing of bacterial cells compared to controls, for intermediate-resistant strains only, at concentrations of 1,000 and 2,000 ?g/ml.

SUBMITTER: Tom SK

PROVIDER: S-EPMC4704188 | biostudies-literature | 2016 Jan

REPOSITORIES: biostudies-literature

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Effect of High-Dose Antimicrobials on Biofilm Growth of Achromobacter Species Isolated from Cystic Fibrosis Patients.

Tom Sean K SK Yau Yvonne C W YC Beaudoin Trevor T LiPuma John J JJ Waters Valerie V

Antimicrobial agents and chemotherapy 20151102 1

MICs and biofilm inhibitory concentrations (BICs) were measured for 68 cystic fibrosis (CF) Achromobacter isolates for amikacin, aztreonam, colistin, levofloxacin, and tobramycin. With the exception of colistin and levofloxacin, the remaining antibiotics had MIC90s, BICs at which 50% of the isolates were susceptible (BIC50s), and BICs at which 90% of the isolates were susceptible (BIC90s) equal to or above the highest concentrations tested. In a biofilm model, tobramycin was able to significantl ...[more]

PMID: 26525791

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Project description:Achromobacter species are increasingly being detected in cystic fibrosis (CF) patients, where they can establish chronic infections by adapting to the lower airway environment. To better understand the mechanisms contributing to a successful colonization by Achromobacter species, we sequenced the whole genome of 54 isolates from 26 patients with occasional and early/late chronic lung infection. We performed a phylogenetic analysis and compared virulence and resistance genes, genetic variants and mutations, and hypermutability mechanisms between chronic and occasional isolates. We identified five Achromobacter species as well as two non-affiliated genogroups (NGs). Among them were the frequently isolated Achromobacter xylosoxidans and four other species whose clinical importance is not yet clear: Achromobacter insuavis, Achromobacter dolens, Achromobacter insolitus and Achromobacter aegrifaciens. While A. insuavis and A. dolens were isolated only from chronically infected patients and A. aegrifaciens only from occasionally infected patients, the other species were found in both groups. Most of the occasional isolates lacked functional genes involved in invasiveness, chemotaxis, type 3 secretion system and anaerobic growth, whereas the great majority (>60%) of chronic isolates had these genomic features. Interestingly, almost all (n=22/23) late chronic isolates lacked functional genes involved in lipopolysaccharide production. Regarding antibiotic resistance, we observed a species-specific distribution of blaOXA genes, confirming what has been reported in the literature and additionally identifying blaOXA-2 in some A. insolitus isolates and observing no blaOXA genes in A. aegrifaciens or NGs. No significant difference in resistance genes was found between chronic and occasional isolates. The results of the mutator genes analysis showed that no occasional isolate had hypermutator characteristics, while 60% of early chronic (<1 year from first colonization) and 78% of late chronic (>1 year from first colonization) isolates were classified as hypermutators. Although all A. dolens, A. insuavis and NG isolates presented two different mutS genes, these seem to have a complementary rather than compensatory function. In conclusion, our results show that Achromobacter species can exhibit different adaptive mechanisms and some of these mechanisms might be more useful than others in establishing a chronic infection in CF patients, highlighting their importance for the clinical setting and the need for further studies on the less clinically characterized Achromobacter species.

Dataset Information

Effect of High-Dose Antimicrobials on Biofilm Growth of Achromobacter Species Isolated from Cystic Fibrosis Patients.

Publications

Effect of High-Dose Antimicrobials on Biofilm Growth of Achromobacter Species Isolated from Cystic Fibrosis Patients.

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