The relationships and susceptibilities of some industrial, laboratory and clinical isolates of Pseudomonas aeruginosa to some antibiotics and biocides.
OBJECTIVE
To provide evidence to support or refute the hypothesis that cross-resistance between antibiotics and biocides can occur.


RESULTS
Fifty-five strains of Pseudomonas aeruginosa were tested for their resistance to anti-pseudomonal antibacterials. Twenty clinical, 19 industrial and 16 culture collection isolates were used. The MIC was found for the antibiotics amikacin, ceftazidime, ciprofloxacin, gentamycin, ticarcillin, tobramycin, imipenem and polymyxin B. The MIC was also found for the biocides benzalkonium chloride and chlorhexidine. The analysis of the data was based on the production of a normal distribution of the log (MIC) plots for each antimicrobial. Strains were then labelled as resistant, intermediate or sensitive based on the mean and standard deviation of the distributions.


CONCLUSIONS
In general the clinical isolates were the most recalcitrant organisms, with the industrial isolates being the most sensitive.


CONCLUSIONS
The work shows that antibiotic/biocide correlations do occur, especially with clinical strains. That such correlations were not found with industrial isolates suggests that the clinical environment is responsible for the correlation. We could infer that it is the selective pressure of antibiotic usage that differentiates the clinical environment from the industrial.
Lambert
R J
RJ
Unilever Research Colworth, Sharnbrook, Bedfordshire, UK. ronnie.lambert@unilever.com
Joynson
J
J
Forbes
B
B
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000891:Anti-Infective Agents, Local / Q000494:pharmacology*; D001548:Benzalkonium Compounds / Q000494:pharmacology*; D002710:Chlorhexidine / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D006801:Humans; D007221:Industry; D007753:Laboratories; D008826:Microbial Sensitivity Tests / Q000379:methods; D011552:Pseudomonas Infections / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000187:drug effects*
D000900:Anti-Bacterial Agents; D000891:Anti-Infective Agents, Local; D001548:Benzalkonium Compounds; D002710:Chlorhexidine