Antimicrobial activity of FK-037 against class I beta-lactamase producing species resistant to ceftazidime: a multi-laboratory clinical isolate sample

Impact of changing pathogens and antimicrobial susceptibility patterns in the treatment of serious infections in hospitalized patients

The selection of drug-resistant pathogens in hospitalized patients with serious infections such as pneumonia, urinary tract infections (UTI), skin and skin-structure infections, and primary or secondary bacteremia has generally been ascribed to the widespread use of antimicrobial agents. Issues of concern regarding gram-negative bacilli include the expression of extended spectrum beta-lactamase-producing Escherichia coli and Klebsiella pneumonias and constitutive resistance in some Enterobacteriaceae caused by Bush group 1 beta-lactamases. Current concerns with gram-positive pathogens are increasing multidrug resistance in methicillin-resistant Staphylococcus aureus, enterococci, and coagulase-negative staphylococci, and increasing incidence of penicillin-resistant Streptococcus pneumoniae. Contemporary treatment strategies for pneumonia in hospitalized patients mandate early empiric therapy for the most likely gram-positive and gram-negative pathogens. Newer beta-lactams, such as fourth-generation cephalosporins, may be useful in the treatment of pneumonia, including those cases associated with bacteremia. Combination beta-lactam/beta-lactamase inhibitor drugs, an aminoglycoside co-drug, or a carbapenem may also be indicated. The initial treatment of UTI in the hospital setting also may be empirically treated with the newer cephalosporins, combination broad-spectrum penicillins plus an aminoglycoside, a quinolone, or a carbapenem. Current problems in treating UTI include the emergence of extended spectrum beta-lactamase-producing Escherichia coli, the tendency of fluoroquinolones both to select for resistant strains of major UTI pathogens and to induce cross-resistance among different drug classes, and beta-lactam and vancomycin resistance of enterococci and coagulase-negative staphylococci. Treatment of skin and skin-structure infections is complicated by the coexistence of gram-positive and gram-negative infections, which may be drug resistant. Both fourth-generation beta-lactams and carbapenems may have in vitro activity against these pathogens; however, where these drugs--with their increased spectra and lower affinity for beta-lactamases and less susceptibility to beta-lactamase hydrolysis--fit into the therapeutic armamentarium remains to be determined. Initial clinical studies appear to be promising, nonetheless. The ability of both nosocomial and community-acquired pathogens to develop resistance to powerful broad-spectrum agents presents a great challenge for prescribing patterns and in the development of new drugs to be relatively resistant to inactivation.

Multicentre comparative study on the antibacterial activity of FK-037, a new parenteral cephalosporin

The in vitro antibacterial activity of FK-037, a new parenteral cephalosporin structurally related to cefpirome and cefepime, was compared with that of cefotaxime, ceftazidime, aztreonam, cefpirome, cefepime, imipenem and meropenem against 1,837 clinical isolates obtained from three Spanish hospitals. FK-037 inhibited 90% of Enterobacteriaceae isolates at < or = 0.25 microgram/ml, with the exception of Enterobacter aerogenes (MIC90 1 microgram/ml), Enterobacter cloacae and Citrobacter freundii (MIC90 8 micrograms/ml). In cefotaxime- and ceftazidime-resistant Klebsiella pneumoniae strains producing SHV-2 and SHV-6 beta-lactamases, the activity of FK-037, cefpirome and cefepime was similar (MIC range 0.25-32 micrograms/ml). In Enterobacteriaceae strains hyper-producing chromosomally inducible beta-lactamases, FK-037 (MIC90 range, 0.25-8 micrograms/ml) was 8- to 16-fold more active than cefotaxime and ceftazidime but two- to eightfold less active than cefpirome and cefepime. FK-037 and cefpirome were twofold more active than ceftazidime and cefepime against Pseudomonas aeruginosa isolates, with MIC90 values of 16 micrograms/ml. The activity of FK-037, cefpirome and cefepime was two- to eightfold lower in ceftazidime-resistant derepressed Pseudomonas aeruginosa mutants. FK-037 (MIC range, 0.12-2 micrograms/ml) and the other beta-lactam agents tested were active against methicillin-susceptible staphylococci; however, only cefpirome and, particularly, FK-037 (MIC90 of 32 micrograms/ml) displayed some activity against methicillin-resistant strains. In penicillin-susceptible, -intermediate and -resistant Streptococcus pneumoniae isolates, the MIC90s of FK-037 were 0.03, 0.5 and 1 microgram/ml, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Antimicrobial activity of cefepime tested against Bush group I beta-lactamase-producing strains resistant to ceftazidime. A multilaboratory national and international clinical isolate study

The potency of cefepime, a parenteral aminothiazolyl methoxyimino cephalosporin, was assessed against 256 ceftazidime-resistant Gram-negative bacilli from five medical centers in the United States. In addition, cefepime activity was compared with that of ciprofloxacin and imipenem against 506 ceftazidime-resistant Gram-negative bacilli collected during an 11-medical-center international study. All US clinical isolates were susceptible (< or = 8 micrograms/ml) to cefepime except Enterobacter cloacae (94% susceptible) and Pseudomonas aeruginosa (19% susceptible). Enterobacteriaceae isolates from the 11-nation sample were > 80% cefepime susceptible with the exception of those from Brazil (48% susceptible) and Italy (55% susceptible). These international, enteric isolates were also very susceptible to ciprofloxacin (55%-100% susceptible) and imipenem (84%-100% susceptible). Nonenteric organisms (Pseudomonas, Xanthomonas, and Acinetobacter) from the same international locations had overall rates of susceptibility of 47% for ciprofloxacin, 28% for imipenem, and only 5% for cefepime. Cross-resistance between the broad-spectrum cephalosporins (cefepime or ceftazidime) with either imipenem or ciprofloxacin was incomplete. Cefepime appears to have a spectrum of use against a significant number of contemporary, ceftazidime-resistant Gram-negative bacillus isolates worldwide.

Preliminary interpretive susceptibility testing criteria for FK-037 with 30-microgram disks

FK-037, a new parenteral cephalosporin, was tested against 483 organisms from clinical infections to establish preliminary susceptibility testing criteria with 30-micrograms disks. The proposed breakpoint zone diameters were > or = 17 mm (MIC correlate, < or = 8 micrograms/ml) for the susceptible category and < or = 13 mm (MIC correlate, > or = 32 micrograms/ml) for the resistant category. These interpretive guidelines produced no very major (false-susceptible) errors, 2.9% major (false-resistant) errors, and 6.2% minor errors for a total absolute agreement between methods of 90.9%.