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 % ofEnterobacteriaceae isolates at 0.25 µg/ml, with the exception ofEnterobacter aerogenes (MIC90 1 µg/ml),Enterobacter cloacae andCitrobacter freundii (MIC90 8 µg/ml). In cefotaxime-and ceftazidime-resistantKlebsiella pneumoniae strains producing SHV-2 and SHV-6 -lactamases, the activity of FK-037, cefpirome and cefepime was similar (MIC range 0.25–32 µg/ml). InEnterobacteriaceae strains hyperproducing chromosomally inducible -lactamases, FK-037 (MIC90 range, 0.25–8 µg/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 againstPseudomonas aeruginosa isolates, with MIC90 values of 16 µg/ml. The activity of FK-037, cefpirome and cefepime was two- to eightfold lower in ceftazidime-resistant derepressedPseudomonas aeruginosa mutants. FK-037 (MIC range, 0.12–2 µg/ml) and the other -lactam agents tested were active against methicillin-susceptible staphylococci; however, only cefpirome and, particularly, FK-037 (MIC90 of 32 µg/ml) displayed some activity against methicillin-resistant strains. In penicillin-susceptible,-intermediate and -resistantStreptococcus pneumoniae isolates, the MIC90s of FK-037 were 0.03, 0.5 and 1 µg/ml, respectively. The corresponding values forStreptococcus viridans isolates were 0.12, 1 and 8 µg/ml, respectively. In bothStreptococcus pneumoniae andStreptococcus viridans isolates, FK-037 displayed activity similar to that of cefotaxime and cefpirome and slightly higher than that of cefepime.     

In vitro activity of biapenem against beta-lactamase producingEnterobacteriaceae

The activity of biapenem was compared with that of imipenem and cefotaxime against 108 strains of -lactamase producingEnterobacteriaceae. Biapenem and imipenem were very active, inhibiting 90 % of the strains at a concentration of 0.5 µg/ml. Both carbapenems were very active against plasmidic -lactamase producers, with MIC90s below 1 µg/ml. However, the MIC90 of biapenem for cephalosporinase producers was 1 µg/ml. Against strains producing extended-spectrum -lactamases, biapenem exhibited better activity against TEM-type producers (MIC90 0.25 µg/ml) than against SHV-type producers (MIC90 0.5 µg/ml). Overall, the in vitro antibacterial activity of biapenem is similar to that of imipenem.     

In vitro antimicrobial susceptibility of viridans streptococci isolated from blood cultures

The susceptibility of 211 viridans streptococci isolated from blood cultures to eight antimicrobial agents was determined. All the isolates were susceptible to cefotaxime, ceftriaxone, imipenem and vancomycin. Thirty eight percent of the isolates were resistant to penicillin (MICs 0.25 µg/ml). Tetracycline resistance was found in 41 % of the isolates and in 7 % of these strains tetracycline resistance was combined with erythromycin resistance. FiveStreptococcus mitis isolates exhibited increased (MIC 64 µg/ml and 128 µg/ml) or high-level (MIC 500 µg/ml) resistance to gentamicin, kanamycin and tobramycin. Four of these isolates were also resistant to penicillin (MICs 16–32 µg/m). In vitro synergy was not demonstrated for combinations of penicillin and gentamicin against threeStreptococcus mitis isolates with gentamicin MICs of 1000, 128 and 64 µg/ml. Results of this study indicate the importance of monitoring antibiotic resistance trends in viridans streptococci particularly with respect to penicillin and aminoglycoside resistance.     

Nosocomial outbreak of acute gastroenteritis in a neonatal intensive care unit in tunisia caused by multiply drug resistantSalmonella wien producing SHV-2 beta-lactamase

In a Tunisian hospital 27 babies, including 12 who were premature, in a single intensive care unit suffered acute gastroenteritis in the period from January to May 1988. The mean age at the onset of gastroenteritis was 8.4 days; nine babies died.Salmonella wien was isolated from stools (all babies) and blood (4 babies). It was also isolated from the stools of one nurse and from a mattress. Twelve of the babies had received cefotaxime, which was successfully replaced by oral colimycin. The outbreak was stopped by the implementation of infection control measures. All isolates ofSalmonella wien were of the same biotype, and had the same antibiotic resistance pattern (third generation cephalosporins, monobactams, aminoglycosides, chloramphenicol, trimethoprim and sulphonamides) and plasmid DNA restriction pattern. The isolates were all susceptible to a combination of cefotaxime and clavulanic acid (a -lactamase inhibitor), which displayed synergy, suggesting the presence of a -lactamase (geometric mean MICs 11.24 µg/ml for cefotaxime alone and 0.24 µg/ml in combination with 0.1 µg/ml potassium clavulanate). All isolates produced TEM-1 and SHV-2 -lactamase which was not transferable toEscherichia coli by conjugation. The presence of the SHV-2 enzyme inSalmonella wien may allow it to adapt to newer -lactams which is a cause for concern in this hospital.     

Comparative in vitro activity and beta-lactamase stability of RU29246, the active metabolite of HR916B

HR 916B is a new orally absorbed cephalosporin. In tests its active metabolite, RU29246, inhibitedStreptococcus pyogenes, Streptococcus agalactiae andStreptococcus pneumoniae at 0.12 µg/ml, which is similar to the antibacterial activity of cefuroxime, and was more active than cefaclor. It was also more active (MIC 2 µg/ml) than cefixime, cefuroxime, cefaclor and cefotaxime against staphylococci. RU29246 inhibitedEscherichia coli, Klebsiella pneumoniae, Citrobacter diversus, Klebsiella oxytoca, Proteus mirabilis, Providencia stuartii andSalmonella spp. at 1 µg/ml, thus being more active than cefuroxime and cefaclor, but was less active than cefixime and cefotaxime. It did not inhibitPseudomonas aeruginosa and otherPseudomonas spp.,Enterobacter spp.,Serratia marcescens orBacteroides fragilis. RU29246 was not hydrolyzed by TEM-1,Staphylococcus aureus TEM-2 orMoraxella catarrhalis beta-lactamases, but was hydrolyzed by TEM-3 and the chromosomal beta-lactamases ofProteus vulgaris andMorganella morganii. Plasmid and chromosomal beta-lactamases were inhibited by RU29246.     

Interpretive criteria and quality control for antimicrobial susceptibility tests of levofloxacin

To confirm preliminary interpretive breakpoints for prototype 5 µg levofloxacin disks, 490 strains were tested in vitro using commercially manufactured disks. For in vitro susceptibility testing, 5 µg levofloxacin disks can be used with interpretive criteria of 12 mm for resistant (MIC 8.0 µg/ml) and 16 mm for susceptible (MIC 2.0 µg/ml). Proposed quality control limits for tests of levofloxacin are as follows:Escherichia coli ATCC 25922, zones 29–37 mm or MIC 0.008–0.03 µg/ml;Pseudomonas aeruginosa ATCC 27853, zones 19–26 mm or MIC 0.5–2.0 µg/ml;Staphylococcus aureus ATCC 25923, zones 24–31 mm;Staphylococcus aureus ATCC 29213, MIC 0.06–0.25 µg/ml andEnterococcus faecalis ATCC 29212, MIC 0.25–2.0 µg/ml.     

In vitro activity of amphotericin B,flucytosine and fluconazole against yeasts causing bloodstream infections

The in vitro activity of amphotericin B, flucytosine and fluconazole against 95 yeasts causing fungemia in a single institution over the last eight years was determined by a broth macromethod recommended by the National Committee for Clinical Laboratory Standards. All strains were inhibited by amphotericin B concentrations of 1 µg/ml. With flucytosine in most species the MIC50 was between 0.12 and 0.25 µg/ml and the MIC90 was between 0.25 and 1 µg/ml. One exception with flucytosine wasCandida krusei, with an MIC50 and MIC90 of 16 µg/ml and 32 µg/ml, respectively. Overall, 12 % of the isolates needed at least 8 µg/ml of fluconazole to be inhibited. Fluconazole was very active againstCandida albicans, Candida tropicalis andCryptococcus neoformans, with MIC50 ranging from 0.12 to 0.5 µg/ml and MIC90 of 1 µg/ml, and somewhat less active againstCandida parapsilosis (MIC50 of 1 µg/ml and MIC90 of 4 µg/ml). Fluconazole exhibited poor in vitro activity againstCandida krusei (MIC50 and MIC90 of 64 µg/ml) andTorulopsis glabrata (MIC50 of 4 µg/ml and MIC90 of 16 µg/ml). High MICs of fluconazole were found for four strains ofCandida albicans, one with an MIC of 4 µg/ml and three (5.7 %) with MICs of 16 µg/ml. Previous exposure to fluconazole could be demonstrated in two of these strains. Further work must be done in order to determine appropriate breakpoints of antifungal agents, to assess the clinical relevance of azole resistance in yeasts causing bloodstream infections and to identify risk factors for infections with azole-resistant yeasts.     

In vitro activity of OPC-17116 compared to other broad-spectrum fluoroquinolones

The in vitro activity of OPC-17116 was compared to that of five similar fluoroquinolones (ciprofloxacin, enoxacin, norfloxacin, ofloxacin and temafloxacin). A total of 700 isolates from recent cases of clinical bacteremia were tested. Fifty additional stock strains with well-characterized resistance mechanisms were also processed. The minimal concentrations inhibiting 90 % of strains (MIC90) ofEnterobacteriaceae species were for OPC-17116 0.015–0.5 µg/ml and for ciprofloxacin 0.015–0.25 µg/ml.Moraxella catarrhalis, Haemophilus influenzae andNeisseria gonorrhoeae were very susceptible to OPC-17116 (MIC90 0.015 µg/ml) thus being fourfold more active than ciprofloxacin. For all -hemolytic streptococci and pneumococci OPC-17116 MICs were 0.5 µg/ml. The most resistant enteric bacilli were among theCitrobacter freundii andProvidencia rettgeri strains (MIC90 0.5 µg/ml).Pseudomonas aeruginosa strains were comparably susceptible to OPC-17116 (MIC90 0.5 µg/ml). Low pH and CO₂ incubation had an adverse effect on OPC-17116 MICs, and resistance development was documented among current clinical isolates of staphylococci, pseudomonas and someEnterobacteriaceae.     

Susceptibility ofBacteroides non-fragilis and fusobacteria to amoxicillin,amoxicillin/clavulanate,ticarcillin, ticarcillin/clavulanate,cefoxitin, imipenem and metronidazole

The susceptibility of 234Bacteroides non-fragilis strains and 56 fusobacteria from 12 European centers to amoxicillin, amoxicillin/clavulanate, ticarcillin, ticarcillin/clavulanate, cefoxitin, imipenem and metronidazole was tested and related to -lactamase production. Beta-lactamase production was detected in 42.3 % of theBacteroides strains and 26.8 % of the fusobacteria. The MIC90 of amoxicillin for -lactamase-negative strains was 0.5 µg/ml and the MIC90 of ticarcillin 2.0 µg/ml. In the case of -lactamase-positive strains the MIC90 of amoxicillin (32 µg/ml) and ticarcillin (16 µg/ml) dropped to 1.0 µg/ml upon addition of clavulanate; 65.8 % of these strains were susceptible to amoxicillin and 98.2 % to ticarcillin, but all were susceptible when clavulanate was added. All strains were susceptible to imipenem and metronidazole, and 99.3 % to cefoxitin.     

Interpretive criteria and quality control parameters for determining bacterial susceptibility to fosfomycin tromethamine

Studies with fosfomycin tromethamine disks containing 200 µg of fosfomycin and 50 µg of glucose-6-phosphate confirmed the following zone diameter criteria for the NCCLS method: 12 mm for resistant (MIC256 µg/ml), 13–15 mm for intermediate (MIC 128 µg/ml) and 16 mm for susceptible (MIC64 µg/ml). Additional studies defined acceptable MIC and zone diameter ranges for the following quality control strains:Escherichia coli ATCC 25922, MIC 0.5 to 4.0 µg/ml, zone diameter 23 to 29 mm;Staphylococcus aureus ATCC 25923, zone diameter 26 to 32 mm;Pseudomonas aeruginosa ATCC 27813, MIC 2.0 to 8.0 µg/ml; andEnterococcus faecalis, ATCC 29212, MIC 16 to 64 µg/ml.     

Interpretive criteria for CI-960, fleroxacin and temafloxacin susceptibility tests withHaemophilus influenzae

Haemophilus influenzae strains with varied ampicillin resistance and beta-lactamase production patterns were tested against three investigational fluorinated quinolones (CI-960, fleroxacin, temafloxacin) using Haemophilus Test Medium (HTM) and National Committee for Clinical Laboratory Standards (NCCLS) methods. The disk diffusion zones and MICs were compared and regression statistics and scattergrams generated. The rank order of the agents according to activity againstHaemophilus influenzae was CI-960 (MIC50 0.002 µg/ml) > temafloxacin (MIC50 0.015 µg/ml) > fleroxacin (MIC50 0.03 µg/ml). The recommended susceptibility interpretive criteria for the 5-µg disks of each drug were: for CI-960 23 mm (MIC correlate 1 µg/ml); for fleroxacin 19 mm (MIC correlate 2 µg/ml); and for temafloxacin 16 mm (MIC correlate 2 µg/ml). All recentHaemophilus influenzae isolates tested were susceptible to these potent fluoroquinolones and no interpretive errors were observed.     

In vitro activity and beta-lactamase stability of the new oral cephalosporin Bay v 3522

The activity of the new oral cephalosporin Bay v 3522 was compared to that of six other beta-lactam agents. Bay v 3522 inhibited methicillin-susceptibleStaphylococcus aureus andStaphylococcus epidermidis at 2 µg/ml, compared to MICs of 8 µg/ml for the other cephalosporins tested. It was more active againstStreptococcus pyogenes (MIC 0.06 µg/ml) than cefuroxime, cefixime, cephalexin and cefaclor. Groups B, C and G streptococci were inhibited at 0.12 µg/ml, while the MIC90 forStreptococcus bovis and viridans streptococci was 0.5 and 2 µg/ml, respectively. The MIC90 for enterococci andListeria monocytogenes was 8 µg/ml.Clostridium perfringens was inhibited by 0.12 µg/ml, but mostBacteroides spp. were resistant. The MIC90 for beta-lactamase positiveEscherichia coli (producing primarily TEM-1) was >64 µg/ml and for beta-lactamase negative strains 16 µg/ml. The MIC90 for high-level beta-lactamase producingKlebsiella pneumoniae was >64 µg/ml versus 4 µg/ml for other isolates. The MIC90 forMoraxella catarrhalis was 2 µg/ml, forHaemophilus influenzae 1 µg/ml, and forNeisseria gonorrhoeae 4 µg/ml.Enterobacter cloacae, Citrobacter freundii, Proteus mirabilis, Providencia spp. andPseudomonas aeruginosa were resistant. Bay v 3522 was destroyed by TEM-1, SHV-1, TEM-3 and P99 beta-lactamases.     

Use of a DNA hybridization method to verify results of screening for methicillin resistance in Staphylococci

Tests were performed by the disk diffusion method, agar dilution method and the E test to determine the susceptibility to methicillin and oxacillin of clinical isolates and control strains ofStaphylococcus aureus (n=106) and coagulase-negative species (n=131). Results were compared with those of a dot blot DNA hybridization test, in which themecA gene was detected using an oligonucleotide probe selected from themecA gene. Among theStaphylococcus aureus strains themecA gene was found in all but two strains inhibited by 8 mg/l of methicillin and all but two strains inhibited by 4 mg/l of oxacillin. A disk test using either 1 µg oxacillin or 10 µg methicillin and a tentative resistance breakpoint of 10 mm gave the best agreement with the hybridization test. For coagulase-negative staphylococci 34 of 35 strains inhibited by 8 mg/l methicillin hybridized with the probe as well as 58 of 82 strains inhibited by 1–4 mg/l; 93 of 97 strains inhibited by 0.5 mg/l oxacillin were also positive in the probe test. Using the 1 µg oxacillin disk and a resistance breakpoint of 10 mm good agreement was obtained between results of the disk diffusion and DNA hybridization tests. It is suggested that this genotypic method for detection of methicillin resistance is used as a reference method for routine methods.     

In vitro activity of E-4868, a new trifluoroquinolone,compared to six similar compounds

The compound E-4868 (Laboratorios Dr. Esteve) is a trifluoro, 7-azetidinyl quinolone with properties resembling those of other fluoroquinolones. Its activity in vitro was compared to that of six other similar drugs against more than 700 nosocomial isolates using standard methods. The MIC50s of E-4868 for enteric bacilli ranged from 0.015 to 0.25 µg/ml, being highest forProvidencia spp.Pseudomonas aeruginosa strains were two-fold more susceptible to E-4868 than to ofloxacin. MICs of E-4868 forHaemophilus influenzae, Moraxella catarrhalis and pathogenicNeisseria spp. were all 0.12 µg/ml. E-4868 was equal in activity to or eight-fold more active than ciprofloxacin against gram-positive cocci. The MICs of E-4868 for pneumococci were all 0.5 µg/ml but anaerobes such asBacteroides fragilis were generally less susceptible (MIC90, 4 µg/ml). There was almost complete cross-resistance to several other fluoroquinolones. Resistant mutants were selected by a multiple passage technique but the rate of mutation to resistance was very low (< 10^–8) at an 8 x MIC.     

Ceftibuten (7432-S,SCH 39720): Comparative antimicrobial activity against 4735 clinical isolates,beta-lactamase stability and broth microdilution quality control guidelines

The antimicrobial activity of ceftibuten, a new oral cephalosporin, was evaluated using 4735 clinical bacterial isolates processed at four medical centers. Ceftibuten inhibited nearly 92 % of allEnterobacteriaceae ( 8.0µg/ml), thereby being markedly superior to cefixime which inhibited 78.7 % at 1.0µg/ml and cefuroxime which inhibited 45.1 % at 2.0µg/ml. Pseudomonads and staphylococci were not within the spectrum of activity of ceftibuten. Ceftibuten was found to be very stable in the presence of five commonly occurring beta-lactamases of both the chromosomal-mediated (P99, K1) and plasmid-mediated (CARB-2, OXA-1, TEM-1) types. Only Type Ia (P99) beta-lactamase was significantly inhibited by ceftibuten. On the basis of results of a ceftibuten MIC quality control study conducted in five laboratories, a quality control range of 0.12 to 0.5µg/ml is recommended for theEscherichia coli ATCC 25922 strain.Contributing investigators included: Dr. S. D. Allen, Indianapolis, Indiana, USA; Dr. L. W. Ayers, Columbus, Ohio, USA; Dr. P. C. Fuchs, Portland, Oregon, USA; Dr. E. H. Gerlach, Wichita, Kansas, USA; Dr. M. Pfaller, Iowa City, Iowa, USA.     

Comparative activity of various compounds against clinical strains of herpes simplex virus

The following compounds were evaluated for their inhibitory activity against clinical strains of herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) in both primary rabbit kidney (PRK) and HeLa cell cultures: (S)-9-(3-hydroxy-2-phosphonylmethoxypropyl)adenine (HPMPA), 9-(2-phosphonylmethoxyethyl)adenine (PMEA), (S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine (HPMPC), (RS)-9-(3-hydroxy-2-phosphonylmethoxypropyl)-2,6-diaminopurine (HPMPDAP), 5-(5-bromothien-2-yl)-2-deoxyuridine (BTDU), 5-(5-chlorothien-2-yl)-2-deoxyuridine (CTDU), 9-(2-deoxy-2-hydroxymethyl--D-erythro-oxetanosyl)guanine (OXT-G), pentosan polysulfate, heparin, dextran sulfate (MW 10,000), acyclovir, 9-(2-hydroxyethoxymethyl)guanine (ACV), (E)-5-(2-bromovinyl)-2-deoxyuridine (BVDU), 1--D-arabinofuranosyl-(E)-5-(2-bromovinyl)-uracil (BVaraU), vidarabine (9--D-arabinofuranosyladenine) (ara-A) and phosphonoformate (PFA). The most potent inhibitors of HSV-1 were (in order of decreasing activity in PRK cells) BVDU, ACV, BVaraU and OXT-G, their mean 50 % inhibitory concentration (IC₅₀) ranging from 0.02 µg/ml to 0.9 µg/ml. Then followed BTDU and CTDU (IC₅₀ 1–2 µg/ml), the sulfated polysaccharides (IC₅₀ 1.3–5.8 µg/ml), the phosphonylmethoxyalkyl derivatives (IC₅₀ 5.6–25 µg/ml), ara-A (IC₅₀ 11 µg/ml) and PFA (IC₅₀ 38.5 µg/ml). Except for BVDU, BVaraU, BTDU and CTDU, the compounds did not discriminate between HSV-2 and HSV-1. All the compounds studied could be considered specific anti-HSV agents. Their selectivity indexes varied from 3 (PFA) to 6400 (BVDU).     

Comparative in vitro activity of the new oxazolidinones DuP 721 and DuP 105 against Staphylococci and Streptococci

The in vitro activity of DuP 721 and DuP 105, two orally active members of the oxazolidinones, was compared with that of glycopeptides and ciprofloxacin against 185 gram-positive isolates. Ninety percent ofStaphylococcus aureus isolates, including penicillin- and methicillin-resistant strains, were inhibited by DuP 721 at 1 µg/ml and by DuP 105 at 16 µg/ml; DuP 721 inhibited 90% of coagulasenegative staphylococci tested at 1 µg/ml. The MIC90 forStreptococcus faecalis was 4 µg/ml with DuP 721 and 16 µg/ml with DuP 105; DuP 721 inhibited 90% of -hemolytic streptococci of group A at 0.5 µg/ml. Similar results on selected strains were obtained by continuously recording the optical density of cultures.     

Bacteremia due to fluoroquinolone-resistantEscherichia coli in two immunocompromised patients

Two patients with acute leukemia developedEscherichia coli bacteremia while receiving oral ofloxacin for antibacterial prophylaxis during profound neutropenia. The isolates were resistant to ofloxacin (MIC 25 and 12.5 µg/ml respectively), other fluoroquinolones and several unrelated agents. Whole cell drug accumulation studies with four different fluoroquinolones suggested major differences between drugs but only minor alterations in individual drug permeability in the two resistant isolates compared with a susceptible control strain. In a supercoiling assay using the purified DNA gyrase and plasmid pBR322, high concentrations (250 µg/ml) of both ofloxacin and ciprofloxacin were needed for visible inhibition of enzyme activity suggesting mutations in the DNA gyrase gene as the significant mechanism of resistance in both strains.     

Beta-lactamase production and susceptibility of US and European anaerobic gram-negative bacilli to beta-lactams and other agents

The susceptibility of 1,476 US and European strains of anaerobic gram-negative bacilli to amoxicillin, amoxicillin/clavulanate, ticarcillin, ticarcillin/clavulanate, cefoxitin, imipenem and metronidazole was determined. All of theBacteroides fragilis group and 51 % of the non-Bacteroides fragilis group were -lactamase positive. Amongst the non-Bacteroides fragilis group, -lactamase positivity rates were higher for US strains (58 %) than for European strains (39 %). All strains were susceptible to imipenem and metronidazole. MIC90s of amoxicillin and ticarcillin for all -lactamase negative strains were 0.5 and 2 µg/ml, respectively. The addition of clavulanate reduced the MIC90s of amoxicillin ( 256 µg/ml) and ticarcillin ( 64 µg/ml) to 16 and 8 µg/ml, respectively, for theBacteroides fragilis group, and to 4 µg/ml for both agents for the non-Bacteroides fragilis -lactamase producing group. Twenty-nine cefoxitin-resistant strains were found, mainly in theBacteroides fragilis group, while 95 -lactamase producing strains (predominantlyBacteroides fragilis group and fusobacteria) did not show synergy between -lactams and clavulanate. Of the newer agents tested, meropenem and piperacillin-tazobactam were the most active (100 % of strains susceptible), followed by amoxicillin-BRL 42715 (99 % of strains susceptible); 94 to 98 % of the strains were susceptible to cefoperazone-sulbactam, tosufloxacin, tempafloxacin and clindamycin. Only 73 % of the strains were susceptible to cefotetan, compared to 91 % to cefoxitin; 88 % of the strains were susceptible to trospectomycin. Overall, all of the -lactam/-lactamase inhibitor combinations, imipenem, meropenem, cefoxitin, tosufloxacin, temafloxacin and clindamycin had good activity against -lactamase producing strains, while all agents tested had good activity against -lactamase negative strains.     

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.