In vitro activity of ceftazidime, cefepime and imipenem on 1,005 Pseudomonas aeruginosa clinical isolates either susceptible or resistant to beta-lactams.
BACKGROUND
Recently, new 'fourth-generation' cephalosporins, such as cefepime and cefpirome, were introduced into antibacterial chemotherapy.


METHODS
In order to explore whether these new cephalosporins offer real advantages against Pseudomonas aeruginosa, we matched the in vitro activity of cefepime with that of ceftazidime and imipenem as reference compounds.


RESULTS
Among the 1,005 clinical isolates tested, 86.6% were susceptible to ceftazidime, whereas 80.7 and 76.9% were susceptible to imipenem and cefepime, respectively. Furthermore, the activity of the three compounds against a significant number of clinical isolates of P. aeruginosa expressing different resistance mechanisms to beta-lactam antibiotics was investigated. Among these isolates, 62.5% were still susceptible to ceftazidime, and 52.1 and 38.7% were inhibited by imipenem and cefepime, respectively.


CONCLUSIONS
Ceftazidime and imipenem retained their activity against the majority of clinical P. aeruginosa isolates collected in Italy. Cefepime did not offer competitive advantages in terms of in vitro activity.
Bonfiglio
G
G
Dipartimento di Scienze Microbiologiche, Università di Catania, Catania, Italia. bonfigio@mbox.unict.it
Marchetti
F
F
D000077723:Cefepime; D002442:Ceftazidime / Q000494:pharmacology*; D002510:Cephalosporinase / Q000378:metabolism; D002511:Cephalosporins / Q000494:pharmacology*; D006801:Humans; D015378:Imipenem / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000201:enzymology / Q000302:isolation & purification; D013845:Thienamycins / Q000494:pharmacology; D018440:beta-Lactam Resistance / Q000502:physiology
D002511:Cephalosporins; D013845:Thienamycins; D015378:Imipenem; D000077723:Cefepime; D002442:Ceftazidime; D002510:Cephalosporinase