Comparative in vitro activity of cefepime (BMY 28142) against multiresistant nosocomial isolates ofPseudomonas aeruginosa

The in vitro activity of a new parenteral cephalosporin cefepime (BMY 28142) was compared with that of ceftazidime, cefotaxime, piperacillin, imipenem, gentamicin, amikacin and ciprofloxacin against 173 recent multiresistantPseudomonas aeruginosa isolates of nosocomial origin using an agar dilution technique with an inoculum of 10⁴ CFU per spot. The activity of cefepime was comparable to that of ceftazidime, superior to that of cefotaxime, piperacillin, gentamicin and amikacin, but inferior to that of imipenem and ciprofloxacin. Cross-resistance ofPseudomonas aeruginosa to ceftazidime and cefepime occurred in nearly 50% of the cefepime resistant strains and 61.5% of the ceftazidime resistant strains respectively.     

Comparative in vitro activity of cefdinir (CI-983; FK-482) against staphylococci,gram-negative bacilli and respiratory tract pathogens

The in vitro activity of cefdinir (CI-983; FK-482), a new oral cephalosporin, was compared with that of other antimicrobial agents against clinical isolates of staphylocci, gram-negative bacilli and common respiratory tract pathogens. Cefdinir (MIC90 2.0 µg/ml) was more active than cefixime (MIC90 >64 µg/ml) and equally as active as cefuroxime (MIC90 2.0 µg/ml) against oxacillin-susceptible staphylococci. Cefdinir was active againstHaemophilus influenzae, including -lactamase producers (MIC90 0.5 µg/ml),Moraxella catarrhalis (MIC90 0.12 µg/ml),Streptococcus pneumoniae (MIC90 0.06 µg/ml) andStreptococcus pyogenes (MIC90 0.06 µg/ml). The activity of cefdinir against gram-negative bacilli was variable; organisms with chromosomal cephalosporinases were often resistant.     

Comparative activity of the new fluoroquinolone rufloxacin (MF 934) against clinical isolates of gram-negative and gram-positive bacteria

The antibacterial activity of the new fluoroquinolone rufloxacin (MF 934) was evaluated against 1095 clinical isolates and compared with that of other quinolones and various commonly used antibiotics. Rufloxacin was highly effective against members of theEnterobacteriaceae, inhibiting 98 % of the isolates at a concentration of 1 mg/l. Ninety-two percent ofAeromonas hydrophila and 65 %Acinetobacter strains tested were inhibited by 1 mg/l of rufloxacin, whereas 98 % of methicillin-susceptible and 87 % of methicillin-resistantStaphylococcus aureus strains and 76 % of coagulase-negative staphylococci strains required 4 mg/l for growth inhibition. The MIC values of rufloxacin for most bacteria were 4–16 times higher than those of ciprofloxacin and norfloxacin. Rufloxacin had little activity against xanthomonads, pseudomonads and enterococci. Approximately 95–96 % of isolates ofPseudomonas aeruginosa were inhibited by 2 mg/l of ciprofloxacin and norfloxacin as compared to 29 % inhibited by rufloxacin at this concentration.     

Comparative in vitro activity of the new quinolone fleroxacin (RO 23-6240)

RO 23-6240 (fleroxacin), pefloxacin, augmentin, cefaclor, cef-uroxime, ceftazidime, vancomycin, piperacillin and amikacin were tested against a wide variety of gram-positive and gram-negative bacteria. The MICs of fleroxacin were very similar to those of pefloxacin. Against all the bacterial groups tested, the quinolones compared favorably with the other antimicrobials tested, particularly against the more resistant species such asCorynebacterium group JK and D2 and methicillin-resistant staphylococci.     

Comparative in vitro activities of five quinolone antibiotics, including gemifloxacin, against clinical isolates

The in vitro activities of ciprofloxacin, ofloxacin, norfloxacin, levofloxacin and gemifloxacin against 343 clinical isolates were compared. Gemifloxacin showed the greatest activity, with MIC₉₀ values as low as 0.03–0.25 mg/L against Streptococcus pneumoniae , Haemophilus influenzae , Moraxella catarrhalis , methicillin-susceptible Staphylococcus aureus and Klebsiella pneumoniae , while methicillin-resistant Staphylococcus aureus , Enterococcus spp., Pseudomonas spp., Acinetobacter spp., Escherichia coli and Enterobacter spp. strains exhibited low rates of susceptibility to all five fluoroquinolones.     

Comparative in vitro activity of the new difluoro-quinolone temafloxacin (A-62254) against bacterial isolates from cancer patients

The in vitro activity of temafloxacin, a new difluoro quinolone agent, against 725 bacterial isolates representing 32 species was evaluated in comparison with that of ciprofloxacin. Temafloxacin inhibited the majority ofEnterobacteriaceae isolates at a concentration of0.5 µg/ml. It was also extremely active againstAcinetobacter spp. andAeromonas hydrophila. Its activity was 2–8fold less than that of ciprofloxacin against most gram-negative isolates. Methicillin-susceptible and methicillin-resistantStaphylococcus aureus, coagulase-negativeStaphylococcus spp.,Streptococcus spp.,Listeria monocytogenes, Bacillus spp. and group JK corynebacteria were inhibited at concentrations equal to that of ciprofloxacin.     

In vitro activity of isepamicin and other aminoglycosides against clinical isolates of Gram-negative bacteria causing nosocomial bloodstream infections.

BACKGROUND AND PURPOSE: Isepamicin is a newly introduced aminoglycoside in Taiwan. Since in vitro data for isepamicin against nosocomial Gram-negative bloodstream infection from Taiwan are limited, we compared the activity of isepamicin, amikacin, gentamicin and tobramycin against nosocomial Gram-negative blood isolates. METHODS: A total of 247 non-duplicate nosocomial blood isolates of Gram-negative bacteria collected between January 2003 and December 2003 in a major teaching hospital in Taiwan were tested for their in vitro susceptibilities to gentamicin, tobramycin, amikacin, and isepamicin using the agar dilution method. The isolates included Escherichia coli (31 isolates), Klebsiella pneumoniae (31), Enterobacter cloacae (30), Serratia marcescens (31), Morganella morganii (21), Citrobacter freundii (10), Pseudomonas aeruginosa (31), Acinetobacter baumannii (31), and Stenotrophomonas maltophilia (31). RESULTS: Overall, isepamicin had high antibacterial activity against the tested Gram-negative bacteria. For the 154 Enterobacteriaceae isolates, isepamicin had the lowest minimum concentration inhibiting 90% of isolates (MIC90) among the tested drugs, while its resistance rate (3.9%) was equal to that of amikacin (3.9%) and lower than those of tobramycin (18.2%) and gentamicin (21.4%). For the 93 of non-fermentative Gram-negative bacilli isolates, isepamicin had the lowest MIC90, and a resistance rate (23.7%) lower than those of amikacin (27.9%), tobramycin (38.7%) and gentamicin (40.9%). CONCLUSIONS: The in vitro activity of isepamicin against Gram-negative bacteria isolates was equal or similar to amikacin and superior to other tested aminoglycosides. In view of its potential for less nephrotoxicity and ototoxicity than other aminoglycosides, isepamicin is a drug of choice for the empirical treatment of nosocomial infections caused by Gram-negative bacteria.     

Comparative activity of meropenem (SM-7338) against major respiratory pathogens and amikacin-resistant nosocomial isolates

Meropenem, a new broad-spectrum carbapenem antibiotic, demonstrated excellent in vitro activity against major respiratory pathogens includingMoraxella catarrhalis, Haemophilus influenzae andStreptococcus pneumoniae. Minimal inhibitory concentrations of meropenem forMoraxella catarrhalis andHaemophilus influenzae isolates were frequently less than those of imipenem. For nosocomial amikacin-resistant gram-negative bacilli, meropenem had eightfold lower MIC90 values compared to imipenem against strains ofSerratia marcescens, Enterobacter cloacae andEscherichia coli; it was 32-fold more active than imipenem againstProteus mirabilis isolates. Activity was similar to that of imipenem againstPseudomonas aeruginosa isolates. Overall, meropenem showed excellent activity against common community-acquired pathogens as well as amikacin-resistant nosocomial pathogens.     

Comparative in vitro activity of A-56268 (TE-031) against gram-positive and gram-negative bacteria andChlamydia trachomatis

The in vitro activity of A-56268 (TE-031) was determined and compared with that of 13 antibiotics against 401 gram-positive and gram-negative bacteria and 11 strains of Chlamydia trachomatis.A-56268 was very active against methicillin-susceptible Staphylococcus aureus and Neisseria gonorrhoeae,and was among the most active of the agents tested against Listeria monocytogenes,streptococci and Chlamydia trachomatis.It was moderately active against Haemophilus spp.,Vibrio spp.,Campylobacter jejuni and Campylobacter fetus subsp. fetus.It was inactive against enterococci, methicillin-resistant Staphylococcus aureus,Staphylococcus epidermidis, Campylobacter coli, Salmonella spp.,Shigella spp. and Yersinia enterocolitica.A-56268 was not consistently bactericidal or more active than erythromycin for any organism except Chlamydia trachomatis.     

In vitro activity of the new quinolone BAY y 3118 against anaerobic bacteria

The in vitro activity of BAY y 3118 against anaerobic cocci,Propionibacterium acnes, Clostridium perfringens, Clostridium difficile, Bacteroides fragilis, otherBacteroides spp. and fusobacteria was determined by an agar dilution method. This activity was compared with that of ciprofloxacin, ofloxacin, piperacillin, cefoxitin, imipenem, clindamycin and metronidazole. BAY y 3118, imipenem, clindamycin and metronidazole were the most active agents tested. The in vitro activity of BAY y 3118 against anaerobic bacteria was superior to that of ciprofloxacin and ofloxacin.     

In vitro antibacterial activity of enoxacin (CI-919)

Antibacterial activity of enoxacin was evaluated against more than 3,700 clinical isolates using the agar-dilution method and an inoculum of 10(4)-10(5) cells per site. For comparison other antibiotics appropriate for each species were also included. For most enterobacteria and for Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa, the MIC90 of enoxacin was below 2 mg/l. Serratia marcescens was more resistant; the MIC90 being 4 mg/ml. Enoxacin also showed high activity against Campylobacter jejuni and Neisseria gonorrhoeae. Streptococci were comparatively resistant, 32 mg/l to 64 mg/l of the compound being required to inhibit 90% of strains.     

Antistaphylococcal activity of the fluoroquinolones CI-960, PD 131628, sparfloxacin,ofloxacin and ciprofloxacin

Five fluoroquinolones were tested against 300 staphylococci from a wide variety of US medical centers including 150 strains resistant to penicil-linase-resistant penicillins (PRP-resistant). Ten ciprofloxacin-resistant strains of PRP-resistantStaphylococcus aureus were relatively resistant to the other fluoroquinolones, but the remaining 290 isolates were susceptible to all five drugs at established or anticipated breakpoint concentrations. The relative potency of the study drugs could be ranked as follows: CI-960>PD 131628>sparfloxacin > ciprofloxacin > ofloxacin. All five drugs were bactericidal against PRP-resistant and PRP-susceptible staphylococci.     

Comparative in vitro activity of the new oxacephem antibiotic,flomoxef (6315-S)

The in vitro activity of flomoxef (6315-S) was determined and compared to that of different cephalosporins against 787 clinical isolates of staphylococci,Enterobacteriaceae and anaerobes. Flomoxef is similar in activity to latamoxef and cefotaxime againstEnterobacteriaceae, slightly more active than cephalothin and cefamandole against oxacillin-sensitive strains ofStaphylococcus aureus and minimally less active than cefamandole against oxacillin-resistant strains. Flomoxef showed similar or better activity than latamoxef and cefoxitin against most of the anaerobic species of medical importance.     

Antibacterial activity of the new carbapenem meropenem (SM-7338) against clinical isolates

The in vitro antibacterial activity of the new carbapenem antibiotic meropenem (SM-7338) against 567 clinical isolates was evaluated. SM-7338 exhibited activity against a broad spectrum of organisms, including aerobes and anaerobes, and was superior to the other beta-lactam drugs tested (piperacillin, cefotaxime, ceftazidime, ceftriaxone, cefoxitin). SM-7338 was more active than imipenem, gentamicin and amikacin againstEnterobacter cloacae andPseudomonas aeruginosa. SM-7338 was less potent than imipenem against staphylococci and enterococci, but the activity of the two antibiotics against anaerobes was similar. SM-7338 and imipenem showed a high bactericidal activity at a concentration of 2–4 x MIC.     

Bacteriological activity of trovafloxacin, a new quinolone, against respiratory tract pathogens

The use of established fluoroquinolones, such as ciprofloxacin and ofloxacin, as empirical therapy for the treatment of moderate-to-severe respiratory tract infections is limited by their poor activity against gram-positive and atypical pathogens. Data from in vitro susceptibility studies and in vivo animal protection models suggest that the new fluoroquinolone, trovafloxacin, compared with ciprofloxacin and ofloxacin offers equivalent activity against gram-negative pathogens and improved activity against gram-positive pathogens. In particular, susceptibility data indicate that trovafloxacin is at least 16-fold more potent than either ciprofloxacin or ofloxacin against penicillin-susceptible and penicillin-resistant strains ofStreptococcus pneumoniae. Other susceptible pathogens includeStreptococcus pyogenes, vancomycin-susceptibleEnterococcus faecalis and the atypical respiratory pathogensLegionella pneumophila, Mycoplasma pneumoniae andChlamydia pneumoniae. In vivo studies involving models of protection against acute systemic infection and pneumococcal pneumonia in mice, and Legionnaires' disease in guinea pigs, indicate that the antibacterial spectrum observed for trovafloxacin in vitro extends to the in vivo setting. Together, these findings suggest that trovafloxacin may offer clinical efficacy against respiratory pathogens superior to that of ciprofloxacin and of ofloxacin, and may find a useful role as empiric therapy in both the community and hospital setting.