Mechanisms of beta-lactam resistance in Pseudomonas aeruginosa: prevalence of OprM-overproducing strains in a French multicentre study (1997).
One hundred and forty-three non-repetitive strains of Pseudomonas aeruginosa were collected in 13 French hospitals in 1997. A decreased susceptibility or resistance to ticarcillin (MIC > 16 mg/L) was found in 61 isolates (43%) and this was attributed to three major mechanisms: (i) overexpression of OprM and hence related efflux components such as MexAB or MexXY (42.6%), (ii) production of acquired beta-lactamase (29.5%) and (iii) overexpression of chromosomally encoded AmpC cephalosporinase (21.3%). Four of seven 'intrinsically' resistant strains (11.5%) with normal amounts of OprM were shown to produce low levels of AmpC, whereas in three isolates no resistance mechanism to beta-lactams could be identified. Overproduction of OprM thus appears as an important mechanism of ticarcillin resistance in French isolates of P. aeruginosa.
Cavallo
J D
JD
Hôpital d'Instruction des Armées Bégin, 69 Avenue de Paris, 94163 St Mandé, France. hia-begin-biologie@worldonline.fr
Plesiat
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P
Couetdic
G
G
Leblanc
F
F
Fabre
R
R
D001425:Bacterial Outer Membrane Proteins / Q000096:biosynthesis* / Q000187:drug effects / Q000302:isolation & purification; D005602:France / Q000453:epidemiology; D006801:Humans; D026901:Membrane Transport Proteins / Q000096:biosynthesis* / Q000187:drug effects / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*; D018440:beta-Lactam Resistance / Q000502:physiology*
D001425:Bacterial Outer Membrane Proteins; D026901:Membrane Transport Proteins; C402263:OprM protein, Pseudomonas aeruginosa