Extended antimicrobial resistance screening of the dominant faecal Escherichia coli and of rare resistant clones.
Fifty faecal samples from healthy adults were grown on MacConkey agar and three pink colonies were subcultured, identified to species level and their antimicrobial susceptibility determined. Forty-seven samples yielded 141 isolates of Escherichia coli that were susceptible to most antimicrobials. Resistance was noted for ampicillin (30.5%), chloramphenicol (12.1%), tetracycline (23.4%), trimethoprim (24.8%) and co-trimoxazole (22.7%). A direct faecal plating method was used for extended resistance screening with E. coli as the indicator organism. Zone breakpoints were determined using normalised resistance interpretation and gave similar susceptibility results. Eighty-eight isolates of E. coli from within the zones of inhibition revealed four times more antimicrobial resistance. Extended antimicrobial resistance screening both provides the susceptibility profile of the dominant E. coli isolate and detects greater resistance in rare isolates.
Kronvall
Göran
G
Clinical Microbiology - MTC, Karolinska Institute, Karolinska Hospital L2:02, SE-17176 Stockholm, Sweden. goran.kronvall@labmed.ki.se
Larsson
Mattias
M
Borén
Charlotte
C
Kahlmeter
Gunnar
G
Bartoloni
Alessandro
A
Rossolini
Gian Maria
GM
Grape
Malin
M
Kristiansson
Charlotte
C
Karlsson
Inga
I
D000667:Ampicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002353:Carrier State; D002701:Chloramphenicol / Q000494:pharmacology; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology; D005243:Feces / Q000382:microbiology; D005493:Folic Acid Antagonists / Q000494:pharmacology; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods; D013752:Tetracycline / Q000494:pharmacology; D014295:Trimethoprim / Q000494:pharmacology; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D005493:Folic Acid Antagonists; D002701:Chloramphenicol; D000667:Ampicillin; D015662:Trimethoprim, Sulfamethoxazole Drug Combination; D014295:Trimethoprim; D013752:Tetracycline