In vitro and in vivo changes of serotype in Pseudomonas aeruginosa isolates by anti-pseudomonal drugs.
The present study was designed to clarify whether anti-pseudomonal drugs affected in vitro and in vivo changes in serotypes of Pseudomonas aeruginosa isolates. Forty-two isolates of P. aeruginosa belonging to different serotype groups were each incubated in Mueller-Hinton broth including piperacillin, cefsulodin, ceftazidime, imipenem, gentamicin or norfloxacin at 1 approximately 4 MICs at 35 degrees C for 20 hours. The bacterial cells in the media were serotyped after the incubation. In each experiment with these six drugs, serotypes of 4 (9.5%) to 8 (19.0%) of the 42 isolates changed to other different groups. There was no relationship between the serotypes of the variants formed with the anti-pseudomonal drugs and kinds of the drugs. In the case of P. aeruginosa TA-2 isolate, the different concentrations (1/2 MIC and 2 x MIC) of cefsulodin induced the distinct changes in serotypes such as the poly-agglutinable (M, G) and non-typable groups, respectively. The time course for the formation of the variant cells was investigated during the incubation of P. aeruginosa TA-2 isolate in the presence of cefsulodin, respectively. In this case, the variant cells appeared 6 hours after incubation and continued to grow together with the intact cells. On the other hand, the variant cells with anti-pseudomonal drugs (cefsulodin, imipenem and gentamicin) were also formed in the model infections in mice. The present results indicated that the co-existence of colonies with different serotypes in some isolates of P. aeruginosa was partially due to the alternation of serotypes with anti-pseudomonal drugs given to patients with infection.
Kobayashi
I
I
Chemotherapy Division, Mitsubishi Yuka Bio Clinical Laboratories, Inc., Tokyo, Japan.
Hasegawa
M
M
Miyazaki
S
S
Nishida
M
M
Goto
S
S
D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D006801:Humans; D051379:Mice; D008813:Mice, Inbred ICR; D008826:Microbial Sensitivity Tests; D011552:Pseudomonas Infections / Q000188:drug therapy*; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000472:pathogenicity; D012703:Serotyping
D000900:Anti-Bacterial Agents