[Drug-resistance patterns of clinical isolates of Pseudomonas aeruginosa in regard to their lipopolysaccharide-chain sizes].
Pseudomonas aeruginosa strains isolated from patients with different types of the infections each consisted of LPSs different in chain sizes. The drug-susceptibility patterns of these strains of P. aeruginosa were investigated to clarify the relationship between the LPS-compositions and susceptibility to some kinds of anti-pseudomonal drugs. The susceptibilities of nineteen strains (seven long-LPS strains, four short-LPS strains and eight LPS-deficient strains) to piperacillin, ceftazidime, gentamicin, norfloxacin and polymyxin-B were determined and these strains were classified into six types (Types I-VI) according to their drug-resistance patterns. Six of the eight LPS-deficient strains were found to be highly resistant to gentamicin alone (Type IV). Four of the seven strains with the long-LPS and one strain with the short-LPS were resistant to three drugs such as piperacillin, ceftazidime and norfloxacin, and classified into Type I. These results indicated that the major part of the LPS-deficient strains and the considerable part of the long-chain LPS strains of P. aeruginosa tested had each characteristic profile in the drug resistance. The outer membrane proteins of thirteen strains, consisting of different types of LPS compositions, were analyzed by SDS-PAGE. The strains belonging to the same types of the drug-resistance patterns were found to have similar OMP-profiles, although a few exceptions were found. beta-lactamase and gentamicin-inactivating activities were determined for piperacillin-resistant and gentamicin-resistant strains, respectively. Of the piperacillin-resistant strains tested, the activity of beta-lactamase was high in one (No. 8) only, low in four and not found in four. The results showed that degrees of resistance of P. aeruginosa strains tested to piperacillin did not correlate to their producibility of beta-lactamase except one strain. Of the nine gentamicin-resistant strains tested, the gentamicin inactivating activity was high in one (No. 30) only, moderate in six and low in two. These results suggested that the significant levels of piperacillin- or gentamicin-resistance of P. aeruginosa isolated tested might be expressed each due to their decreased abilities for drug-permeabilities in addition to drug-inactivating activities such as beta-lactamase or gentamicin-modifying enzyme. In the case of some resistant strains, the resistance to piperacillin or gentamicin was not explained by the results of the present study. Therefore, we must investigate the possibility that other mechanisms participate in the resistance of these strains.
Hasegawa
M
M
Chemotherapy Division, Mitsubishi Kagaku Bio Clinical Laboratories, Inc., Tokyo, Japan.
Kobayashi
I
I
Saika
T
T
Nishida
M
M
D004352:Drug Resistance, Microbial; D006801:Humans; D008070:Lipopolysaccharides / Q000378:metabolism*; D011552:Pseudomonas Infections / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000378:metabolism
D008070:Lipopolysaccharides