Effect of temperature on antimicrobial susceptibilities of Pseudomonas maltophilia.

Abstract

SUMMARY After a case of peritonitis caused by Pseudomonas maltophilia had occurred 20 strains of the organism were investigated and the minimum inhibitory concentrations of a variety of antibiotics determined at 30°C and 37°C. There was a significant difference in susceptibility between 30°C (most resistant) and 37°C (most susceptible) for aminoglycosides and polymyxin B. No difference was seen with the other agents or in strains of Ps aeruginosa and Enterobacteriaceae tested under similar conditions. The possible mechanisms of this phenomenon are discussed below.

Synergistic interactions of ciprofloxacin and extended-spectrum beta-lactams or aminoglycosides against multiply drug-resistant Pseudomonas maltophilia

“…The in vitro susceptibility of P. maltophilia recorded here was similar to that previously reported by Felegie et al (9) and several others (3,6,13,15), all of whom demonstrated the multiple resistance of these organisms to antipseudomonal ,-lactams and aminoglycosides. Our data indicated that ciprofloxacin and the quinolones from Abbott Laboratories (difloxacin and A-56620) were also only moderately active.…”

In vitro activities of antimicrobial combinations against Stenotrophomonas (Xanthomonas) maltophilia

“…L1 and related ␤-lactamases are group 3 metallopenicillinases and carbapenemases (1,7,15,20,30,33), while L2 and related ␤-lactamases are group 2e cephalosporinases capable of hydrolyzing penicillins and monobactams (1,7,15,20,29,32). All ␤-lactamases are induced synchronously, indicating an apparent overlap of regulatory systems (1,22,30).In vitro susceptibility testing of S. maltophilia is problematic, and results obtained by such tests should be interpreted with caution (1,6,10,13,16,21,38). The National Committee for Clinical Laboratory Standards (NCCLS) (26) currently recommends broth or agar dilution testing as the method of choice for susceptibility testing for this organism.…”

“…In vitro susceptibility testing of S. maltophilia is problematic, and results obtained by such tests should be interpreted with caution (1,6,10,13,16,21,38). The National Committee for Clinical Laboratory Standards (NCCLS) (26) currently recommends broth or agar dilution testing as the method of choice for susceptibility testing for this organism.…”

Role of Phosphoglucomutase of Stenotrophomonas maltophilia in Lipopolysaccharide Biosynthesis, Virulence, and Antibiotic Resistance

“…A number of factors, including multidrug efflux pumps (1, 3, 65) and outer membrane impermeability (13, 37), likely contribute to the intrinsic antibiotic resistance of S. maltophilia. A key component of the outer membrane is lipopolysaccharide (LPS), and changes in LPS structure have been correlated with changes in resistance to a variety of antimicrobial agents (reviewed in reference 41).Several groups have investigated LPS in S. maltophilia in an effort to assess its contribution to antimicrobial resistance in this organism (43)(44)(45)60). S. maltophilia exhibits a temperature-dependent variation in susceptibility to several antibiotics, including aminoglycosides and polymyxin B (60), whose activities are known to be affected by LPS (44), but not quinolones, ␤-lactams, and chloramphenicol (44, 60).…”

“…Several groups have investigated LPS in S. maltophilia in an effort to assess its contribution to antimicrobial resistance in this organism (43)(44)(45)60). S. maltophilia exhibits a temperature-dependent variation in susceptibility to several antibiotics, including aminoglycosides and polymyxin B (60), whose activities are known to be affected by LPS (44), but not quinolones, ␤-lactams, and chloramphenicol (44, 60).…”