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The bactericidal activity in vitro of cefpirome plus either vancomycin or teicoplanin was compared with that of a cefamandole-vancomycin combination against ten clinical isolates of homogeneous methicillin-resistant Staphylococcus aureus. Cefpirome (0.125 x MIC) combined with vancomycin (0.5-2 x MIC) or teicoplanin (0.5-4 x MIC) acted synergically against the ten isolates. Similar effects were observed with the cefamandole-vancomycin combination, except that for one isolate, higher cefamandole concentrations (0.25-1 x MIC) were required.

The objective of this study was to characterize virulence factors of Escherichia coli isolates from broilers with simultaneous occurrence of cellulitis and other colibacillosis lesions. Thirty flocks were sampled and 237 birds with cellulitis were examined. Eighty-two (34.6%) of 237 birds condemned for cellulitis had gross lesions in the heart, air sacs, joints, or liver. In 58 chickens, E. coli was isolated from both the cellulitis and other lesions of colibacillosis, and 18.9% of the E. coli isolates from the 2 types of lesions belonged to the same O group. Escherichia coli of serogroups O78, O1, and O2 predominated. Isolates of the same serogroup that were derived from different lesions in the same birds had similar patterns of biotype, aerobactin production, serum sensitivity profile, antibiotic sensitivity, and K1 capsule production. Escherichia coli derived from cellulitis lesions produced virulence factors similar to those found in E. coli isolated from other colibacillosis lesions in poultry.

Gutta-percha points containing calcium hydroxide, zinc oxide (ZnO), a mixture of ZnO and chlorhexidine (ZnO/CHX), iodine-polyvinylpyrrolidone (ZnO/J-PVP), or a mixture of CHX and J-PVP and ZnO (ZnO/CHX/J-PVP) were tested for their ability to inhibit growth of pure cultures of bacterial species commonly involved in endodontic infections (Peptostreptococcus micros, Streptococcus intermedius, Enterococcus faecalis, and Porphyromonas gingivalis). To quantitate growth inhibition, an in vitro assay was established that controlled for important parameters of root canal infection. Approximately 10(7) bacteria per assay were suspended in diluted human serum and co-incubated with the gutta-percha points in an anaerobic atmosphere for up to 2 wk. Aliquots used for determination of colony counts were taken on days 0, 1, 2, 4, 7, and 14 of incubation. As judged by colony-forming unit reduction kinetics and final counts, calcium hydroxide had better growth inhibitory activity than ZnO/CHX, ZnO/J-PVP, and ZnO alone for all bacteria tested except Peptostreptococcus micros. The combination of CHX and J-PVP with ZnO did not render results different from those of ZnO/CHX or ZnO/J-PVP. The results of this study support the introduction of standardized assays for testing antibacterial properties of root canal medications under conditions that more closely resemble those encountered in endodontal infections.

The duration of time that serum levels are above the minimum inhibitory concentration (MIC; TMIC) seems to be an important pharmacodynamic parameter for beta-lactams. The aim of this study was to evaluate the bactericidal activity of cefodizime and ceftriaxone in a pharmacokinetic model mimicking the concentrations in bronchial mucus and in serum (total and free) obtained at 2, 4, 8, 12 and 24 h, after 1 g i.m. administration once daily. The species investigated were respiratory pathogens (1 strain of Staphylococcus aureus, 2 strains of Streptococcus pneumoniae, 1 strain b-lactamase negative and 1 strain beta-lactamase positive of Haemophilus influenzae, 1 strain of Escherichia coli and 1 strain of Klebsiella pneumoniae); MIC50s of the chosen strains were reported. In this in vitro model the concentrations (serum and bronchial mucus) for both antibiotics are generally at or above the MIC values of the tested strains until 24 hours. The killing curve showed rapid killing for both antibiotics: 99.9% killing (a 3-log reduction in growth) within 6 to 8 h, depending upon the microorganism tested. There was no significant difference in the log kill between cefodizime and ceftriaxone. These data confirm that TMIC for beta-lactams is the pharmacodynamic parameter which best correlates with bactericidal efficacy. On the basis of the killing curve determined for cefodizime versus ceftriaxone at concentrations that these antibiotics can reach during therapy with 1 g i.m. once daily we expect reasonable clinical efficacy with monoadministration of cefodizime as well as for ceftriaxone in respiratory tract infections.

After oral administration of 500 mg of levofloxacin to 12 volunteers, we investigated the pharmacokinetics and serum bactericidal activities (SBAs) against five strains of members of the family Enterobacteriaceae . Pharmacokinetic data were as follows: maximum concentration in serum, 6.36 ± 0.57 mg/liter; area under the concentration-time curve, 43.6 ± 6.23 mg · h/liter; elimination half-life 4.23 ± 0.87 h. SBAs were present for 24 h against Escherichia coli and Citrobacter freundii . The SBAs at 1, 12, and 24 h after administration against E. coli were 1:108, 1:29, and 1:7, respectively, and those against Citrobacter freundii were 1:74, 1:25, and 1:7, respectively. The SBAs were present for 12 h against the other three organisms tested. The SBAs against Serratia marcescens were 1:28 and 1:9 at 1 and 12 h, respectively; the SBAs against Klebsiella pneumoniae were 1:25 and 1:7 at 1 and 12 h, respectively; and the SBAs against Enterobacter cloacae were 1:24 and 1:10 at 1 and 12 h, respectively.

Tobramycin is an aminoglycoside used in the treatment of infection against gram-negative bacteria. Tobramycin cannot be delivered orally probably due to efflux of drug by a P-glycoprotein pump in the brush border of the small intestine. In this report we demonstrate oral delivery of tobramycin in FVB mice using CRL-1605 copolymer as a vehicle. This copolymer is known to inhibit P-glycoprotein. Two different doses of tobramycin (25 mg/kg and 200 mg/kg) were used. The concentration of CRL-1605 copolymer was 132 mg/kg. The liquid formulation was fed to mice by gavage and serum tobramycin concentrations were measured after one and two hours using the fluorescence polarization immunoassay. We observed significant increases in serum tobramycin concentrations when the drug was delivered orally with the copolymer compared to when the drug was delivered alone. We also performed a bioassay using Bacillus subtilis to confirm antibacterial effect of tobramycin in mice sera. This was to ensure that tobramycin did not undergo structural change during oral absorption when delivered in the copolymer vehicle. We observed minimal inhibition in growth of Bacillus subtilis in sera obtained from mice fed with tobramycin alone. In contrast, we observed almost complete inhibition of growth (most specimens) in sera obtained from mice fed with tobramycin in the presence of CRL-1605 copolymer. We conclude that tobramycin delivered orally in mice using copolymer 1605 is also bioactive.

How providers of external quality assessment (EQA) programmes relate to and interact with the monitors and watchdog of clinical laboratory performance in the UK is described. With regard to the quality of antibiotic assays, the changes in methodologies and in performance quality between 1971 (when the UK NEQAS for Antibiotic Assays began) and 1999 is reviewed. How improvements in performance and changes of methodology are related is discussed. The findings and conclusions of two experimental pilot EQA distributions (the teicoplanin assay and serum bactericidal test) are also discussed.

Background: Although ciprofloxacin exhibits more intense microbiological activity against Pseudomonas aeruginosa than does trovafloxacin, the clinical relevance of this observation remains questionable, particularly when the agents are combined with another antipseudomonal agent. Methods: To evaluate this further, we conducted a four-way crossover trial to compare the bactericidal activities of ciprofloxacin and trovafloxacin, alone and in combination with cefepime, against three clinical isolates of P. aeruginosa. Healthy subjects received the following regimens, dosed to steady state: trovafloxacin 300 mg/24 h; ciprofloxacin 400 mg/12 h; trovafloxacin 300 mg/24 h plus cefepime 2 g/12 h, and ciprofloxacin 400 mg/12 h plus cefepime 2 g/12 h. Serum bactericidal titers were performed with each regimen. Results: As monotherapy, the area under the bactericidal curve for ciprofloxacin exceeded that of trovafloxacin for all isolates. No significant difference in the overall degree of bactericidal activity was noted for two of three P. aeruginosa isolates for the combination regimens. Additionally, both combination regimens provided bactericidal activity for 100% of the dosing interval for all isolates. Conclusion: These results indicate that, while in vitro differences exist among these quinolones for P. aeruginosa, when a fluoroquinolone is combined with a β-lactam, this is likely to be of little clinical significance.

The effectiveness of ziracin (SCH27899), a novel everninomicin, was at first investigated against lethal pneumonia caused by a penicillin-susceptible Streptococcus pneumoniae strain. A single intravenous injection of ziracin at a dose of 60 mg/kg of body weight given at 18 h postinfection protected 100% mice and led to the complete clearance of bacteria from their lungs. The activity of ziracin was observed to be the same as that of ceftriaxone: the 50% protective doses (PD 50 s) of ziracin and ceftriaxone were 24.8 and 24.6 mg/kg, respectively. Evaluation of this therapy with leukopenic mice showed that a single injection of ziracin protected 75% of these mice. A delay in therapy with ziracin, which was initiated at 48 h postinfection with 30 mg/kg given once daily for 3 days, resulted in an 83% survival rate of immunocompetent mice. The efficacy of ziracin was further compared to that of vancomycin against lethal pneumonia caused by a penicillin-resistant S. pneumoniae strain in leukopenic mice. The PD 50 s of ziracin and vancomycin were 40.5 and 44.2 mg/kg, respectively. Treatment with ziracin at 30 mg/kg once daily for 2 days (initiated 18 h postinfection) yielded an 83% survival rate and achieved complete eradication of the bacteria. The results were the same as those obtained with vancomycin administered at 15 mg/kg twice daily for 2 days. It is notable that the high survival rates for mice treated with ziracin were associated with effective eradication of the bacteria and rapid recovery of pulmonary tissues from pneumonia. The pharmacokinetic properties of ziracin, ceftriaxone, and vancomycin were estimated following intravenous administration of a single dose of 30 mg/kg to immunocompetent mice. The half-life of ziracin was observed to be longer than those of ceftriaxone and vancomycin (2.3 h versus 1.0 and 0.36 h in the bloodstream and 3 h versus 1.9 and 0.45 h in lung tissues). The areas under the concentration-time curves (AUCs) in lung tissue for ziracin versus those for ceftriaxone and vancomycin were 36 μg · h/g versus 20 and 9.5 μg · h/g. The prolonged half-life and high AUC for ziracin in tissue contributed to its excellent in vivo activities.

A randomized open-label study was conducted to compare the pharmacokinetics and pharmacodynamics of grepafloxacin with those of clarithromycin in patients with chronic bronchitis whose sputa were colonized with potential bacterial pathogens. Patients received oral grepafloxacin 400 mg od for 10 days (n = 15) or oral clarithromycin 500 mg bd for 10 days (n = 10). Sputum samples were collected before the first dose, 1, 4 and 8 h after a dose on day 1 and then before a dose on days 2, 3, 5, 7 and 10 to determine the time to eradication (T(erad)) of the potential bacterial pathogens. Blood samples for measurement of grepafloxacin or clarithromycin and 14-hydroxyclarithromycin concentrations were obtained before a dose and 1, 2, 4, 8 and 12 h after doses on days 1 and 5. The area under the inhibitory serum concentration-time curve over 24 h (AUIC(24)), peak serum concentration:MIC ratio (C(max):MIC) and the percentage of the dosing interval during which the serum concentration exceeded the MIC (%tauMIC) were calculated and serum inhibitory titres (SITs) were determined. Haemophilus spp. were the predominant potential bacterial pathogens and were recovered from the sputa of 24 patients. Strains of Streptococcus pneumoniae were isolated from two patients in the grepafloxacin group and a strain of Moraxella catarrhalis was isolated from one patient in the clarithromycin group. Haemophilus spp. isolates were eradicated from the sputa of 13 of 14 (93%) patients given grepafloxacin, but from only two of 10 (20%) patients given clarithromycin (P0.05). In the other eight (80%) patients who received clarithromycin, the sputum cultures remained positive throughout the 10 day course. Grepafloxacin eliminated potential bacterial pathogens more quickly than clarithromycin (median T(erad) 4 h versus 76 h). The S. pneumoniae strains were eradicated by grepafloxacin within 4 h and the single M. catarrhalis strain was eradicated by clarithromycin within 1 h. The greater efficacy of grepafloxacin, compared with that of clarithromycin, in terms of the incidence and speed of eradication of the Haemophilus spp. isolates, was associated with higher median values of AUIC(24) (169 SIT(-1)*h versus 8.1 SIT(-1)*h), C(max):MIC ratio (23.6 versus 0.7) and %tauMIC (100% versus 0%). A Hill-type model adequately described the relationship between the percentage probability of eradicating potential bacterial pathogens from sputa and the plasma grepafloxacin concentration.

A retrospective evaluation of the relationship between serum bactericidal and inhibitory titres and treatment outcome in 195 adult Thai patients with severe melioidosis was conducted. Drug regimens included ceftazidime (52% of patients), co-amoxiclav (24%), imipenem (11%) or the conventional four-drug combination (11%). Pre- and 1 h post-dose serum samples were collected after 48-72 h of therapy, and serum inhibitory and bactericidal titrations determined. Median post-dose titres were: bactericidal 1:8 (range 0-1:128) and inhibitory 1:16 (range 0-1:128). Overall mortality was 26% and outcome was not influenced by either inhibitory or bactericidal titres. Pre-dose titres correlated with renal function; renal function was the most important predictor of mortality. Determination of serum inhibitory or bactericidal titres is unhelpful in the management of severe melioidosis.

A whole-blood assay (WBA), which assesses the complete bactericidal activity of blood, was compared with the serum bactericidal assay (SBA), which measures antibody and complement mediated cell lysis. Twenty children infected with serogroup B strains and 25 infected with serogroup C strains were studied 8–12 weeks after disease, and 29 healthy children were used as controls. The infecting strain (convalescent children only) and two reference strains, MC58 (B:15:P1.7, 16) and NCTC 8554 (C:NT:P1.5) were used. In children previously infected with a serogroup B strain, bactericidal activity was detected in 95% and 85% to their infecting strain by the WBA (>50% killing) and the SBA (s), respectively. Bactericidal activity to the reference serogroup B and C strain was detected by WBA in 70 and 75% of children, respectively, and the SBA in 45% and 20%. In contrast bactericidal activity was detected to both serogroup C strains in >80% of children previously infected with a serogroup C strain using either assay and in 48% (WBA) and 20% (SBA) to the reference serogroup B strain. Levels of bactericidal activity were detectable in fewer control children. Children convalescing from meningococcal disease develop an immune response to their infecting strain, detectable by both the WBA and SBA, which is independent of age. However, the WBA appears to be a more sensitive measure of bactericidal activity to heterologous strains than the SBA.

Eight adult bottlenose dolphins Tursiops truncatus (six male, two female) were employed in a single-dose study of orally administered enrofloxacin dosed at 5 mg/kg body weight. Blood samples were obtained from all animals at 0, 2, 4, 8, 12 and 24 h following administration of the dose in the animals morning ration of fish. Serum antimicrobial activity concentrations (SAAC) were determined using bioassay. The mean elimination half-life (t1/2) of enrofloxacin and its major metabolites was 6.4+/-2.0 h with a range of 3-9.4 h. The time of maximal serum concentration (tmax) occurred at approximately 4 h with a range of 2-8 h following a single oral dose of 5 mg/kg. This variation in tmax most likely resulted from individual differences in absorption because of variations in the storage and digestion of the fish ration containing the drug dose within the compartmentalized cetacean stomach.

The objective of the current study was to evaluate the bactericidal activity of levofloxacin against Streptococcus pneumoniae at concentrations equivalent to those present in serum after a po dosage of 500 mg. Nine S. pneumoniae strains (one penicillin G-resistant, one penicillin G-intermediate resistant, and two penicillin G- and cefotaxime-resistant) were exposed to a levofloxacin concentration of 6 mg/L diluted at a terminal half-life ( t½ ) of 8 h. Surviving S. pneumoniae (cfu/mL) were quantified up to 24 h by the membrane filtration method. Levofloxacin was rapidly bactericidal and reduced the quantity of inoculum to below the detection level of 10 cfu/mL within 2.5–5.15 h, irrespective of susceptibility to penicillin G or cefotaxime. No viable S. pneumoniae could be detected at the end of the observation period (24 h). All strains except one (strain 17134) had an MIC < 1.0 mg/L, and the minimum bactericidal concentrations (MBCs) were, at the most, one dilution higher than the respective MICs. The inoculum was high, ranging from 2.9 × 10 5 to 7.5 × 10 6 cfu/mL. The time required to achieve 99% death ranged from 0.9 to 3.1 h, and was longest for strain 17134 which had an MIC of 1.0 mg/L and an MBC of 2.0 mg/L. A 99.9% reduction in inoculum was achieved within 1.5–4.15 h. At a serum concentration achievable after a single po dosage of 500 mg, levofloxacin showed rapid and complete bactericidal activity against the S. pneumoniae strains tested.

The objective of this study was to determine the serum bactericidal activity (SBA) of levofloxacin against Streptococcus pneumoniae strains with various degrees of susceptibility to penicillin and cefotaxime. Serum samples of volunteers ( n = 12) who had received levofloxacin 500 mg as a single po dose were provided in blinded fashion. SBA was determined, using the microdilution method, in Todd–Hewitt broth supplemented with lysed horse blood inoculated with an overnight culture diluted to yield a final concentration of approximately 10 5 cfu/mL. The serum bactericidal titre was defined as the highest dilution of serum showing no growth (>99.9% reduction of inoculum). The duration of SBA ranged from 0.75 to 6.3 h (mean 3.85 h), and was independent of the susceptibility of the strains to penicillin and cefotaxime. In conclusion, a single po dose of 500 mg levofloxacin achieved serum concentrations which were bactericidal against penicillin-resistant S. pneumoniae for a mean period of 3.85 h.

Fluctuating concentrations of three fluoroquinolones (moxifloxacin, sparfloxacin and ofloxacin) and a β-lactam (amoxycillin) were used in vitro to simulate antibiotic concentrations in human serum after oral doses of antibiotics. The antibiotics were tested against Staphylococcus aureus 12241 and Streptococcus pneumoniae 4241. Moxifloxacin and sparfloxacin were also tested against Escherichia coli Neumann. Human serum concentrations of moxifloxacin and ciprofloxacin were also simulated in an in-vivo murine thigh muscle model against S. aureus,S. pneumoniae and E. coli. Ciprofloxacin, sparfloxacin and ofloxacin had a dose-independent effect on Gram-positive organisms beyond their optimal dose that gave a maximum effect, as did amoxycillin. In contrast, moxifloxacin had a dose-dependent and therefore concentration-dependent effect on both Gram-positive and β-lactam-susceptible and-resistant Gram-negative organisms. The marked activity of moxifloxacin against both Gram-positive and Gram-negative organisms was confirmed in an in-vivo model. A human dose equivalent of 200 mg moxifloxacin reduced viable counts of S. pneumoniae below the limit of detection and regrowth did not occur. S. aureus was eliminated almost as effectively as S. pneumoniae. A 200 mg dose of moxifloxacin completely eliminated the original inoculum of E. coli within 6 h. Treatment of S. aureus with ciprofloxacin (250 or 500 mg) resulted in a dose-independent decrease in viable counts by approximately 3.5 log 10 cfu/mL. A 125 mg dose of ciprofloxacin almost completely eliminated the original inoculum of E. coli within 8 h, whereas both the 250 mg and 500 mg doses reduced viable counts below the limit of detection. Thus, the in-vitro and in-vivo pharmacodynamic models used in this study established that moxifloxacin was highly effective against both Gram-negative and Gram-positive bacteria.

Ten volunteers were given each of five antibiotics, sequentially, until steady state was reached. Peak and trough sera were then drawn, and bactericidal titers were determined to two different isolates of Staphylococcus aureus, both sensitive in vitro to all antibiotics tested. The antibiotics were cephalexin, trimethoprim/sulfamethoxazole (TMP/SMZ), clindamycin, dicloxacillin, and ciprofloxacin. Mean peak serum bactericidal titers (SBT) were significantly higher for cephalexin than for dicloxacillin, ciprofloxacin, and TMP/SMZ (P less than .05). The difference between cephalexin and clindamycin did not achieve statistical significance. Dicloxacillin, clindamycin, and ciprofloxacin were not statistically different from each other. Mean SBT for TMP/SMZ was less than 1:2, significantly less than that achieved by the other antibiotics. Only clindamycin achieved a trough SBT greater than 1:2. This was statistically significant compared with each of the other antibiotics.

In previous studies many benzimidazole, imidazole and benzothiazole derivatives had been synthesized and their antimicrobial activities were tested in vitro conditions. Four of these compounds showed minimal inhibitory concentrations (MIC) of 5-25 micrograms/ml against standard strains and clinical isolates. In order to determine whether these four compounds can be used for therapeutic purpose, their serum MIC values and side effects on hepatic and renal functions were determined. Different concentrations of the compounds were tested on Wistar rats. Compound 1 was administered orally, intramuscularly and intravenously; compounds 2, 3 and 4 were given orally and intramuscularly. Blood samples were taken 4 and 24 h after administration of the compounds. Serum MIC values were investigated by bioassay and serum levels of biochemical parameters by autoanalyzer. None of the tested compounds showed antimicrobial activity at their serum concentrations. Although creatinine activity was found at normal levels in all experiments, compounds 1 and 2 caused a significant increase in blood urea nitrogen (BUN) level. The values of aspartate aminotransferase and/or alanine aminotransferase and/or alkaline phosphatase which are characteristic for liver function were generally found at high levels. According to these results, it can be concluded that the tested compounds caused damage in liver and biliary tracts without antimicrobial activity by their serum concentrations.

MK-0991 (formerly L-743,872) is a water soluble semisynthetic echinocandin that possess potent, broad-spectrum antifungal activity. We evaluated the in vitro activity of MK-0991 and an echinocandin derivative LY303366, compared with that of itraconazole, fluconazole, amphotericin B and 5-flucytosine against 400 blood stream isolates of Candida spp. (nine species) obtained from more than 30 different medical centers. MICs for all antifungal drugs were determined by the NCCLS method using RPMI 1640 test medium. Both MK-0991 and LY303366 were very active against all Candida spp. isolates (MIC90, 0.25 and 1 microgram/mL, respectively). MK-0991 was two-fold to 256-fold more active than amphotericin B, fluconazole, itraconazole (except against C. parapsilosis), and 5-flucytosine (except against C. glabrata and C. parapsilosis). LY303366 was comparable to MK-0991, but was fourfold less active against C. tropicalis (MIC90, 0.5 versus 0.12 microgram/mL) and C. parapsilosis (MIC90, > 2 versus 1 microgram/mL). All of the isolates for which fluconazole and itraconazole had elevated MICs (> or = 64 micrograms/mL and > or = 1 microgram/mL, respectively) were inhibited by < or = 0.5 microgram/mL of MK-0991 and LY303366. These results suggest both MK-0991 and LY303366 possess promising antifungal activity and further in vitro and in vivo investigations are warranted.

Experiments in vitro on the bactericidal activity of metronidazole and in the Cornell model of murine tuberculosis.To assess the sterilising activity of maximal metronidazole dosage and its activity against bacilli held dormant by immunity in the mouse.In vitro experiments showed that metronidazole was only bactericidal at attainable concentrations (50-100 microg/ml) under anaerobic conditions. In the Cornell model, isoniazid 25 mg/kg and high dosage pyrazinamide 1000 mg/kg was given in the diet with and without 1500 mg/kg metronidazole for the initial 14 weeks of sterilising chemotherapy. In the subsequent sterile state, metronidazole at 0, 100 and 250 mg/kg was given by daily gavage for 6 weeks. Finally, the mice were given 3 weeks of high dosage steroids and their organs were cultured in selective liquid medium.Metronidazole had no activity either in the initial sterilising phase or in the subsequent sterile state.The O2 tension in the cellular lesions of murine tuberculosis is unlikely to be sufficiently low to allow metronidazole to act. Its activity should be assessed in caseous lesions.

Functional effects of recombinant human granulocyte colony-stimulating factor (rhG-CSF) and recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) were prospectively measured by harvesting blood samples from 51 oncology patients (21 who were receiving no cytokines, 14 receiving rhGM-CSF, and 16 who were receiving rhG-CSF) just before cytotoxic chemotherapy (baseline) immediately before the last cytokine dose (pre), 2 hours after the last cytokine dose (post), and 48 hours after the pre period (follow-up). Neutrophils and monocytes were separated and functional effects were measured by comparing cell-kill percentages, as determined by a microbial cell-kill assay against Staphylococcus aureus and Candida albicans. Optimal cell concentrations (2 x 10(6) monocytes/ml; 4 x 10(6) neutrophils/ml) and effector-to-cell ratios (1:50) were initially determined with blood samples harvested from 23 healthy volunteers. Results in oncology patients indicated that rhGM-CSF improved monocyte-killing activity against S. aureus at follow-up, compared with controls (p = 0.0094) and compared with monocytes from rhG-CSF-treated patients at the post period (p = 0.014). Cell-killing percentage of the rhGM-CSF-treated patients was also enhanced against C. albicans during the post period, compared with controls (p = 0.011) and rhG-CSF-treated patients (p = 0.067). Neutrophil activity was not altered by either cytokine. In conclusion, monocyte-induced microbial killing was enhanced in oncology patients receiving rhGM-CSF after cytotoxic chemotherapy, compared with patients receiving rhG-CSF or no cytokines. No differences in neutrophil activity were observed between patients receiving either cytokine.

The serum bactericidal activity of three oral cephalosporins was studied in 12 volunteers, after administration of single doses of cefuroxime axetil 250 mg, cefixime 200 mg, cefixime 400 mg and cefetamet pivoxil 500 mg. Serum bactericidal activity against clinical isolates of Streptococcus pyogenes, Streptococcus pneumoniae, Haemophilus influenzae and Klebsiella pneumoniae was measured by a standardized microdilution method. Cefuroxime axetil demonstrated the best bactericidal activity against Gram-positive organisms and cefixime was the most bactericidal against Gram-negative bacteria.

Residual chlorhexidine concentrations were measured after application of a single dose on the skin of 22 healthy volunteers. Dosage by high-pressure liquid chromatography in the skin cleansers revealed that the residual concentrations were higher than chlorhexidine MICs for most organisms of the resident skin flora and some responsible for hand-borne infections, even 24 h after application.

Changes in antibiotic susceptibility was evaluated in 77 consecutive nosocomial clinical isolates of Staphylococcus aureus collected from 1986 to 1994 at the Umberto I Polyclinic of the University of Rome (63 isolates) and from 7 other Roman hospitals (14 isolates). Oxacillin resistance in these isolates increased from 39% during the 1980s to 69% during the 1990s. Significant increases in resistance to ciprofloxacin, clindamycin and rifampicin were observed among oxacillin-resistant strains. No resistance to glycopeptides was observed although both teicoplanin and vancomycin had slightly reduced antistaphylococcal activity.

Two isolates of serum-susceptible Campylobacter coli were recovered in a 7-day interval from blood from a patient with hepatocellular carcinoma and liver cirrhosis whose peritoneal-caval (Denver's) shunt malfunctioned. Identical random amplified polymorphic DNA fingerprints, cellular fatty acid chromatograms, and antibiograms of the two isolates indicate that C. coli has the ability to cause catheter-related bacteremia following its colonization of the catheter.

Serum bactericidal activity against a penicillin-susceptible strain and a penicillin-resistant strain of Streptococcus pneumoniae (amoxicillin and cefotaxime MICs, 0.001 and 1 microg/ml, respectively, and MBCs, 0.01 and 2 microg/ml, respectively) was measured in 12 healthy volunteers who each received an oral 875-mg dose of amoxicillin and an intramuscular 1-g dose of cefotaxime in a crossover fashion. The areas under the bactericidal activity-time curves for the two strains were found to be similar for both antibiotics despite the significantly higher (P < 0.002) AUC/MIC and peak level/MIC values for cefotaxime.

Recommendations on treatment of acute staphylococcal osteomyelitis of children, based mostly on retrospective analyses, comprise surgical drainage, up to 6 weeks fo antimicrobials guided by the erythrocyte sedimentation rate, and the possibility of switching to the oral route only if monitoring of serum bactericidal titer is guaranteed. A prospective study was conducted to test whether the treatment could be simplified.Fifty pediatric cases of acute Staphylococcus aureus osteomyelitis were randomized to receive 150 mg/kg/day of cephradine divided in four doses, or 40 mg/kg/day in four doses of clindamycin. The treatment was initiated intravenously, but switched to oral administration mostly within 4 days, using the same doses. The peak antimicrobial serum inhibitory titer or bactericidal titer was not measured. The course of illness was monitored by blood leukocytes, erythrocyte sedimentation rate, and serum C-reactive protein. The follow-up was extended to 1 year posthospitalization.Eight tertiary pediatric-orthopedic hospitals in Finland.Full recovery and remaining healthy at least 12 months from hospital discharge.The lower and upper extremities were affected in 72% and 8% of patients, respectively. No surgery at all or needle aspiration only was performed in 62% and drilling in 38%. C-reactive protein and the sedimentation rate normalized within 9 days and 29 days, respectively. X-ray changes developed in 68% but had no prognostic significance. The mean hospitalization time was 11 days, and the total duration of antimicrobials was 23 days. No failure has occurred nor have long-term sequelae been observed in any patient.Treatment of pediatric acute staphylococcal osteomyelitis can be simplified and costs reduced by keeping surgery at a minimum, shortening hospitalization and the course of antimicrobials, switching quickly to the oral route, and not monitoring serum bactericidal activity.

The effects on Staphylococcus aureus viability and b-lactamase activity of concentrations that simulated those in human serum after a combined dose of 875 mg of amoxicillin and 125 mg of clavulanic acid were studied in an in vitro pharmacodynamic model. Six hours of preexposure to concentrations of the amoxicillinclavulanic acid combination that were higher than the amoxicillin-clavulanic acid MIC led to a reduction of the initial inoculum of >90% and to a significant decrease of b-lactamase activity versus those of the control even from 6 h, when concentrations were subinhibitory. The postantibiotic effect and post-b-lactamase inhibitor effect contributed to these results. b-Lactams exhibit time-dependent activity. To maintain levels higher than the MIC for b-lactamase-producing bacteria for the required time, clavulanic acid was combined with amoxicillin (2/1 [co-amoxiclav]) because of its property of progressively inhibiting b-lactamase (5). In this study, we assessed the in vitro effects of co-amoxiclav, amoxicillin, and clavulanic acid versus that of the control with concentrations, changing over time, of amoxicillin and clavulanic acid that simulated those in human serum on the viability and b-lactamase activity of Staphylococcus aureus NCTC 11561. The MICs of co-amoxiclav, amoxicillin, and clavulanic acid against this strain, which were determined by a standard method (7), were 1, $125, and $125 mg/ml, respectively. The concentrations simulating those in human serum that

Three female Yucatan micropigs were included and received a single dose of amikacin (15 mg/kg) by short infusion (30 min) combined either with a single dose of cefepime or cefpirome (30 mg/kg/12 h) or meropenem (7 mg/kg/8 h). The beta-lactams were administered either by intravenous intermittent injection or by continuous infusion. The mean elimination half-life and clearance value of amikacin were 1.88 h and 2.15 ml/min.kg-1 respectively. These pharmacokinetic parameters were similar to those obtained in man (t1/2 = 2,42 h et Cl = 1,61 ml/min kg-1). Furthermore, they were not affected by coadministration of cefepime, cefpirome and to meropenem. While resistant to cefepime, cefpirome and amikacin, Klebsiella pneumoniae producing ESBL was susceptible to combination of these cephalosporins with amikacin in an in vitro/ex vivo micropig model. For the six dosage regimens used in this study, the killing activities were similar and resulted in at least 4 log decrease at 6 h after drug exposure. For antimicrobial combination consisting of bolus dosing of amikacin plus continuous infusion of cefepime or cefpirome, the 12 h serum bactericidal titers (SBTs) were 1:8 for cefepime and 1:2 for cefpirome dosage regimen. When each drug administered intermittently, the 12 h SBTs were 1:4 for cefepime and 1:2 for cefpirome. The 8 h SBTs for dosing schedule containing meropenem combined with amikacin were 1:4 and 1:16 after 30 min short infusion and continuous infusion respectively. In conclusion, our study showed that the micropig model is a reliable model for pharmacokinetic investigation of amikacin. It was concluded that beta-lactam antibiotics tested with amikacin may be coadministered by using the standard recommended dosing regimen of amikacin. Continuous infusion of beta-lactams combined with once dosing of amikacin seems to be as or more effective than intermittent injection of each drug.

To determine the time above minimum inhibitory concentration (TMIC) and serum bactericidal activity of five oral cephalosporins against two strains of Haemophilus influenzae.Randomized, crossover study.University-associated research center.Ten healthy volunteers.Each subject received a single dose of cefpodoxime 200 mg, cefuroxime 500 mg, cefaclor 500 mg, cefprozil 500 mg, or loracarbef 400 mg each week for 5 weeks. Blood for serum levels was obtained at time zero and 1, 2, 3, 4, 6, 8, and 12 hours after each dose.Cefpodoxime produced serum concentrations above the MIC for more than 90% of the time for both beta-lactamase-negative and -positive strains of H. influenzae. Moreover, it had serum bactericidal activity for 12 hours against both isolates. Cefuroxime was the second most active cephalosporin, with serum concentrations above the MIC of both isolates for 60% of the time. Cefuroxime provided serum bactericidal activity for 12 hours against the beta-lactamase-negative strain and 6 hours against the beta-lactamase-positive strain of H. influenzae. Even though the TMIC was less than 50% of the study period for the other cephalosporins, all but cefaclor provided serum bactericidal activity for 12 hours against the beta-lactamase-negative isolate. Cefaclor provided measurable serum bactericidal activity for only 3 hours. The duration of serum bactericidal activity of cefprozil, loracarbef, and cefaclor against the beta-lactamase-positive isolate was 4, 2, and 0 hours, respectively.Cefpodoxime was the most active cephalosporin studied based on TMIC and serum bactericidal activity against isolates of H. influenzae.

Two hundred microbiology laboratories in the UK took part in two separate experimental external quality assessment distributions related to the serum bactericidal test (SBT). In the first, Staphylococcus aureus NCTC 6571 (vancomycin MIC 1 mg/L), was tested against a human serum containing vancomycin 38 mg/L plus gentamicin 0.5 mg/L. In the second, Streptococcus oralis PAJ 112/4183 (penicillin MBCor = 0.03 mg/L) and Streptococcus sanguis PAJ 107/4184 (penicillin MBC = 128 mg/L) were tested against human serum containing penicillin 15 mg/L. Respondents returned their laboratory results and a questionnaire on clinical interpretation and technical aspects. Most laboratories (194/199, 97.5%) recommend the use of the SBT in the management of infective endocarditis but only 48 (25.2%) often or always change therapy on the basis of the result. A wide range of interpretative criteria, definitions of bactericidal endpoints and methodologies are used. Performance in the first distribution was acceptable for 75% of laboratories but in the second only 34% could identify penicillin tolerance; 34 respondents reported an SBT result ofor = 2 for the tolerant strain, 81 laboratories reported one ofor = 16. Technical factors related to acceptable performance were: sonication of broth before counting the inoculum; knowing the inoculum size in cfu/mL; use of a 4-8 h broth culture to make the inoculum; incubation of recovery plates for36 h; use of a calibrated pipette to sample for surviving bacteria; use of measured volumes to add the inoculum. Use of uncalibrated pipettes or standard loops to recover survivors was related to poor performance. Microbiology departments in the UK should review the clinical need to perform the SBT in the light of their local circumstances and if they elect to continue to offer this test, revise their methodologies which could be producing misleading results when testing alpha-haemolytic streptococci.

Cefuroxime axetil is a cefuroxime ester that can be administered by mouth. Two dosage forms (tablets and granules) have been developed for oral administration. We evaluated the pharmacokinetics and pharmacodynamics of these forms in an open cross-over study involving 12 healthy volunteers receiving single doses of 250 mg. The bioavailability of the two forms was different, the observed peak concentration and time-concentration curve values of the tablet form being, respectively, 39 and 27% higher than those of the granule form. However, ex vivo studies of serum bactericidal activity against Streptococcus pneumoniae showed no significant differences between the two formulations. This is in keeping with the fact that the bactericidal activity of samples from only six subjects gave evaluable data for Haemophilus influenzae; although small differences were found between the two formulations, further investigations are required. The pharmacodynamic approach is becoming an essential element in determining the equivalence of antibiotic dosage forms.

Genotypic and phenotypic tolerance was studied in penicillin treatment of experimental endocarditis due to nontolerant and tolerant Streptococcus gordonii and to their backcross transformants. The organisms were matched for in vitro and in vivo growth rates. Rats with aortic endocarditis were treated for 3 or 5 days, starting 12, 24, or 48 h after inoculation. When started at 12 h, during fast intravegetation growth, 3 days of treatment cured 80% of the nontolerant parent compared with

Transferrin-binding protein B (TbpB) is a surface-exposed protein, variable among strains of Neisseria meningitidis, that has been considered as a vaccine candidate. To define a TbpB molecule that would give rise to broadly cross-reactive antibodies with TbpB of many strains, specific antisera were produced against three recombinant TbpB variants from strain M982: one corresponding to the full-length TbpB; one in which stretches of amino acids located in the central part of the molecule, described as hypervariable, have been deleted; and one corresponding to the N-terminal half of the molecule, described as the human transferrin binding domain. The reactivity of these antisera against 58 serogroup B strains with a 2.1-kb tbpB gene representing different genotypes, serotypes, and subtypes and different geographic origins was tested on intact meningococcal cells. In parallel, the bactericidal activity of the antisera was evaluated against 15 of the 58 strains studied. Of the 58 strains, 56 (98%) reacted with the antiserum specific for the N-terminal half of TbpB M982; this antiserum was bactericidal against 9 of 15 strains (60%). On the other hand, 43 of 58 strains reacted with the antiserum raised to full-length TbpB while 12 of 15 (80%) were killed with this antiserum. The antiserum specific to TbpB deleted of its central domain gave intermediate results, with 53 of 58 strains (91.3%) recognized and 10 of 15 (66.6%) killed. These results indicate that the N-terminal half of TbpB was sufficient to induce cross-reactive antibodies reacting with the protein on meningococcal cells but that the presence of the C-terminal half of the protein is necessary for the induction of cross-bactericidal antibodies.

A sample of 137 coagulase-negative staphylococci isolated from blood cultures in Denmark over a 4-month period during 1992-1993 were tested for aminoglycoside resistance and for the presence of aminoglycoside-modifying enzymes. This was done on the basis of minimum inhibitory concentrations (MICs) measured by agar dilution, inhibition zone diameter by disk diffusion, and DNA dot blot analysis. Using the National Committee for Clinical Laboratory Standards (NCCLS) MIC breakpoints, 5%, 46%, 57%, and 63% of the strains were resistant to netilmicin, amikacin, gentamicin and tobramycin, respectively. The large majority of resistant staphylococci strains produced the bifunctional AAC(6)-III+APH(2") enzyme. The presence of AAC(6)-III+APH(2") explains the high level of resistance to gentamicin, kanamycin and tobramycin. In contrast to our results. Staphylococcus haemolyticus strains are usually reported to be more resistant than Staphylococcus epidermidis strains.

In a randomized crossover study involving 12 healthy volunteers, 1 g of ceftizoxime or cefotaxime was administered intravenously every 12 h for a total of three doses on two separate weekends. The duration of serum bactericidal titers (SBTs) greater than 1:2 and the time serum drug concentrations remained above the MIC (T > MIC) were determined against three clinical isolates of Streptococcus pneumoniae with intermediate resistance to penicillin. The duration of SBTs and T > MIC for both antimicrobial agents exceeded 50% of the dosing interval for all isolates. Ceftizoxime's T > MIC was statistically greater than that of cefotaxime, indicating that its longer half-life in serum (1.7 h) compared with that of cefotaxime (approximately 1 h) compensates for its slightly lower microbiologic activity against the penicillin-resistant pneumococci tested in this study.

Metal compounds have been used as antibacterial agents for centuries. The in-vitro activity of two metal containing complexes, one gold, the other osmium, was investigated using a panel of clinically isolated bacteria and Candida albicans. Twenty strains of each organism were used and MIC and MBC values determined using the agar plate dilution method. Protein binding effects on the activity of the compounds were also investigated using media supplemented with 5% human blood. In-vivo activity of the two compounds was subsequently determined in a hairless-obese mouse skin-surface activity model. Both compounds were highly active against the Gram-positive organisms and Candida albicans in vitro. The gold compound had some Gram-negative activity but the osmium complex was inactive against these organisms. Both were extensively protein bound. In the in-vivo experiment the gold compound achieved a 2-3 log reduction for all the test organisms and was at least as good as or superior to mupirocin in its eradication rate. The osmium compound was inactive.

To simulate peak and trough concentrations, using Bayesian forecasting, achieved with a variety of once-daily dosing (ODD) regimens; to evaluate dosing regimens required to produce target peak and trough concentrations; to compare the peak-to-MIC (minimum inhibitory concentration) ratios and time above MIC for various dosing regimens and MICs; to stratify the information based on renal function estimates; and to use the results from these simulations to make recommendations regarding optimum ODD of aminoglycosides.Simulation of ODD using a Bayesian technique and existing patient data.A tertiary referral, community teaching hospital.One hundred consecutive adults from the author's data base, with a wide variety of infections and underlying illnesses, who met strict inclusion criteria.Two methods of dosing, weight-based (4-7 mg/kg) and target concentration-based (peak 10, 15, or 20 mu g/ml, troughor = 0.3 mu g/ml), were evaluated. Each patient had a known dosing-sampling history, stable renal function, and at least two measured serum concentrations, and were being treated with either gentamicin or tobramycin.A wide range of peak and trough serum concentrations are achieved when dosages are chosen based on patient weight. Even with large dosages, some patients had very low peak-to-MIC ratios and time above the MIC, and vice versa. Variations in MIC had a much greater effect on dosing target values than did variations in dosage. A large degree of variability was also noted in doses and dosing intervals when using a target serum concentration approach. For both methods, an inverse relationship existed between calculated creatinine clearance and time above MIC, although there was little change over the range of 60-119 ml/minute.Bayesian simulation showed that weight-based ODD of aminoglycosides did not produce clinically acceptable serum concentrations or target values in many patients. Young and elderly patients, and any patient with a creatinine clearance below 60 or above 119 ml/minute, are especially likely not to achieve an optimum serum concentration profile. Aminoglycoside ODD should be individualized by evaluating the peak-to-MIC ratio, time above MIC, and patient response.

Twelve adult males participated in a randomized crossover phase I clinical trial comparing serum bactericidal titers (SBTs), urine bactericidal titers (UBTs), and urine killing rates (UKRs) against Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 29213, after the administration of single 400-mg doses of rufloxacin and norfloxacin at different times up to 72 h postdose. SBTs were significantly higher (P 35 mg/ml), median UBTs (>32 for E. coli and 16 for S. aureus) and UKRs for E. coli suggest prolonged urine antibacterial activity (for at least 72 h) and its use as a single 400-mg dose in the treatment of uncomplicated cystitis. Rufloxacin is a broad-spectrum quinolone (24) that is less activeinvitrothannorfloxacinagainstEscherichiacoli(33)and that exhibits a prolonged elimination half-life as a major pharmacokinetic feature (35). Its in vitro activity (7, 33), in conjunction with its pharmacokinetic profile (11), suggest that rufloxacin may well be of clinical use in the treatment of urinary tract infections (33). Rufloxacin and norfloxacin differ in both their pharmacokinetics and their in vitro activities. Measurement of ex vivo bactericidal activity allows for a direct comparison of pharmacodynamic properties (12) in the evaluation of new drugs (2). The area under the bactericidal curve (AUBC) is a sensitive index of the pharmacodynamic effects of a drug (17) and may provide an accurate guide to dosage (8) for those agents exhibiting concentration-dependent killing (25). Taking into account the fact that the measurement of the antibacterial activity in urine correlates directly with the outcome of infection (16) more than the determination of MICs and MBCs and the levels of antibiotics in urine (4) do, we evaluatedtheefficacyofrufloxacinversusthatofnorfloxacinby assessing by urine bactericidal titers (UBTs), serum bactericidal titers (SBTs), and the rate of killing in urine (UKRs) to explore the potential clinical use of rufloxacin in the treatment of urinary tract infections.

Bactericidal activity in sera of children with acute lower respiratory tract infection was assayed to determine its effect on the outcome of blood culture. Parental reporting of prior antibiotic therapy was also determined. 14.4% of samples without serum bactericidal activity yielded pathogens from blood culture, whereas only 2.4% of samples with serum bactericidal activity yielded pathogens. A statistically significant correlation was found between isolation of pathogens by blood culture and serum bactericidal activity. Parental reporting could not be relied upon as there was no positive correlation.

Whether formula or breast feeding influences the functional activity of the complement system from birth to three months of age has been studied. The classical pathway was evaluated by assessing hemolytic activity, based on the capacity of the intact complement system to lyse sheep erythrocytes when coated with specific antibodies. The bactericidal activity of the serum against Staphylococcus aureus and Escherichia coli was used to evaluate the alternative complement pathway. Sera were obtained from neonates (40 +/- 2 weeks of gestation), and one-month or three-month old infants, fed either breast or formula. Control serum was obtained from healthy adults between 22 and 30 years of age. The hemolytic capacity of serum from breast-fed infants of one month and three months of age was significantly greater than that of the serum from infants which had been fed formula milk.

On the basis of MIC data, ciprofloxacin exhibits superior activity against Pseudomonas aeruginosa than the other currently available fluoroquinolones do. Despite the antipseudomonal advantage noted for ciprofloxacin monotherapy, it is unknown whether this advantage is maintained when the fluoroquinolones are used in combination with antipseudomonal beta-lactams such as ceftazidime and piperacillin. Twelve healthy volunteers were enrolled in this open-label, randomized, steady-state, six-way cross-over, comparative trial. All subjects received the following regimens: (i) 400 mg of ofloxacin given intravenously (i.v.) every 12 h (q12h), (ii) 400 mg of ciprofloxacin given i.v. q12h, (iii) 400 mg of ofloxacin given i.v. q12h plus 1 g of ceftazidime given i.v. every 8 h (q8h), (iv) 400 mg of ciprofloxacin given i.v. q12h plus 1 g of ceftazidime given i.v. q8h, (v) 400 mg of ofloxacin given i.v. q12h plus 4 g of piperacillin given i.v. q8h, and (vi) 400 mg of ciprofloxacin given i.v. q12h plus 4 g of piperacillin given i.v. q8h. Serum bactericidal titers with subsequent calculation of the area under the bactericidal curve were determined against three clinical isolates of P. aeruginosa. As monotherapy, ciprofloxacin demonstrated superior antipseudomonal activity than ofloxacin did; however, combination of these agents with ceftazidime yielded remarkably similar and statistically comparable activity profiles. In contrast, ciprofloxacin-piperacillin retained a bactericidal advantage over ofloxacin-piperacillin. Although ciprofloxacin exhibits superior antipseudomonal activity when used as monotherapy, combination of ofloxacin or ciprofloxacin with ceftazidime yielded equivalent activity profiles against susceptible strains of P. aeruginosa.

A serum bactericidal test was established employing human sera of volunteers after intravenous administration of fosfomycin (CAS 23155-02-4) and teicoplanin (CAS 61036-62-2) against 40 staphylococcal strains (20 Staphylococcus aureus and 20 coagulase-negative staphylococci, 10 of each group being susceptible and 10 being resistant to oxacillin). Median serum inhibitory titres were highest for fosfomycin against oxacillin-susceptible Staphylococcus aureus. In the three other groups of strains, the activity of fosfomycin was comparable to that of teicoplanin. The killing curves showed over 99% killing within 24 h for both antibiotics. Here, fosfomycin exerted a rapid killing activity within 4-6 h and was more effective in bacterial growth reduction. It can be concluded that fosfomycin and teicoplanin exerted comparable serum bactericidal antibacterial activity against staphylococci.

Objective: To report on a patient with recurrent methicillin-resistant Staphylococcus aureus (MRSA) osteomyelitis and bacteremia successfully treated with combination antibiotic therapy. Case Summary: Two sets of blood cultures from a 55-year-old man with fever, malaise, and low back pain grew MRSA. Radiologic studies of the spine showed bony changes consistent with osteomyelitis. Soon after completing 6 weeks of vancomycin, the patient experienced a recurrence of back pain. Laboratory values included an increase in the sedimentation rate to 53 mm/h and positive blood cultures for MRSA. Vancomycin, gentamicin, and rifampin were administered for 8 weeks. Serum inhibitory and bactericidal titers were more than 1:1024 for both the peak and trough concentrations. Radiologic studies of the spine showed healing osteomyelitis. Two years after completion of antibiotic therapy, the infection has not recurred. Discussion: Antibiotic therapy alone was attempted because the patient was considered a risky surgical candidate. Serum inhibitory and bactericidal titers documented the high in vivo activity of the vancomycin, gentamicin, and rifampin combination. Initiation of vancomycin therapy led to disappearance of the fever and back pain. Cure was documented by sustained normalization of the erythrocyte sedimentation rate and radiologic evidence of healing. Conclusions: Combination antibiotic therapy with vancomycin, rifampin, and low-dose gentamicin (1 mg/kg q12h) may be useful for deep-seated tissue infection caused by MRSA.