title: Frequency of R factor-mediated multiple drug resistance in Klebsiella and Aerobacter.
abstract: A comparative study was done on the transfer frequency of R factors from 90 strains of multiple drug-resistant Aerobacter and 81 strains of Klebsiella to Escherichia coli CSH-2 (F(-), met(-), pro(-), Nal-r). The most common resistance patterns for the Aerobacter isolants were ampicillin streptomycin chloramphenicol tetracycline and ampicillin streptomycin chloramphenicol tetracycline kanamycin neomycin; for the Klebsiella isolants, the most common resistance pattern was ampicillin kanamycin streptomycin tetracycline chloramphenicol neomycin. R factors were isolated from 14.1% of the Aerobacter strains; 61.5% of these R factors harbored R determinants for ampicillin streptomycin tetracycline. R factors were isolated from 79.1% of the Klebsiella strains; four R factors were isolated with significant frequency; streptomycin chloramphenicol kanamycin neomycin, 37.5%; ampicillin streptomycin tetracycline kanamycin neomycin, 14.1%; ampicillin streptomycin tetracycline, 12.5%; and streptomycin chloramphenicol tetracycline, 12.5%.Chloramphenicol, kanamycin, and neomycin resistance was rarely transferred from the Aerobacter strains, although over 50% of the clinical isolants possessed resistance to these antibiotics. In contrast, over 75% of the Klebsiella strains transferred resistance to chloramphenicol, kanamycin, neomycin. Highest frequency of transferred resistance to individual drugs in the Aerobacter strains was to streptomycin (14.8%), whereas in the Klebsiella group resistance to four drugs was transferred at a very high frequency: streptomycin (80.8%), chloramphenicol (78.5%), kanamycin (76.4%), and neomycin (75.9%).
mesh_terms: D000667:Ampicillin / Q000494:pharmacology; D002701:Chloramphenicol / Q000494:pharmacology; D003227:Conjugation, Genetic; D004754:Enterobacter / Q000187:drug effects*; D004926:Escherichia coli; D005111:Extrachromosomal Inheritance; D005827:Genetics, Microbial; D007612:Kanamycin / Q000494:pharmacology; D007709:Klebsiella / Q000187:drug effects*; D009355:Neomycin / Q000494:pharmacology; D010403:Penicillin Resistance; D013307:Streptomycin / Q000494:pharmacology; D013752:Tetracycline / Q000494:pharmacology
chemical_list: D007612:Kanamycin; D002701:Chloramphenicol; D000667:Ampicillin; D013752:Tetracycline; D009355:Neomycin; D013307:Streptomycin