Brainstem auditory evoked responses in 37 dogs with otitis media before and after topical therapy.

OBJECTIVES: The objective of this study was to determine whether intra-aural administration of aqueous solutions of marbofloxacin, gentamicin, tobramycin and ticarcillin (used off-licence) was associated with changes in hearing as measured by brainstem auditory evoked responses. MATERIALS AND METHODS: Dogs diagnosed with otitis media (n=37) underwent brainstem auditory evoked response testing and then were treated for their ear disease. First, the external ear canal and middle ear were flushed with sterile saline followed by EDTA tris with 0·15% chlorhexidine. Then, a combination of aqueous antibiotic mixed with an aqueous solution of EDTA tris was instilled into the middle ear. Follow-up examinations were undertaken for each dog, and treatment was continued until there were no detected infectious organisms or inflammatory infiltrate. Brainstem auditory evoked response testing was repeated after resolution of the infection and discontinuation of therapy. RESULTS: Brainstem auditory evoked responses in dogs treated with aqueous solutions of marbofloxacin or gentamicin remained unchanged or improved after therapy of otitis media but were impaired in dogs treated with ticarcillin or tobramycin. CLINICAL SIGNIFICANCE: If off-licence use of topical antibiotics is deemed necessary in cases of otitis media, aqueous solutions of marbofloxacin and gentamicin appear to be less ototoxic than aqueous solutions of ticarcillin or tobramycin.

Biological efficacy and stability of diluted ticarcillin-clavulanic acid in the topical treatment of Pseudomonas aeruginosa infections.

Topical compounded Timentin(®) diluted with an inactive vehicle has been reported to be effective in the treatment of otitis externa caused by Pseudomonas aeruginosa. The aims of this study were to determine the biological efficacy of Timentin(®) (ticarcillin and clavulanic acid) when diluted in the carrier vehicle Methopt(®) against P. aeruginosa and to determine the efficacy and stability of Timentin(®) aqueous stock concentrate solution. Timentin(®) stock concentrate was tested against four P. aeruginosa isolates on days 0, 7, 14, 21 and 28; then after 2, 3, 4, 5, 6, 9 and 12 months of storage at 4 or -20°C. The diluted Timentin(®)-Methopt(®) solutions were tested against all isolates after 0, 2, 4, 6, 8, 10, 12, 14, 17, 21, 24 and 28 days of storage at 24 or 4°C. Minimal inhibitory concentration (MIC) levels for all strains were determined using the broth microdilution method. The MIC of the stock solution remained relatively constant and acceptable throughout the study when stored at -20°C and was also acceptable for shorter time periods (6-9 months) when stored at 4°C. The MIC for the diluted Timentin(®)-Methopt(®) solution remained relatively constant and acceptable throughout the study for all four bacterial strains, with no difference between the solutions stored at 4 or 24°C. The results of this study indicate that storage of the Timentin(®) stock solution at -20°C does not compromise efficacy for at least 12 months and that Timentin(®) diluted in Methopt(®) was stable for 28 days when stored at either 4 or 24°C.

Once-daily, high-dose levofloxacin versus ticarcillin-clavulanate alone or followed by amoxicillin-clavulanate for complicated skin and skin-structure infections: a randomized, open-label trial.

This study tested whether levofloxacin, at a new high dose of 750 mg, was effective for the treatment of complicated skin and skin-structure infections (SSSIs). Patients with complicated SSSIs (n=399) were randomly assigned in a ratio of 1:1 to 2 treatment arms: levofloxacin (750 mg given once per day intravenously [iv], orally, or iv/orally) or ticarcillin-clavulanate (TC; 3.1 g given iv every 4-6 hours) followed, at the investigator's discretion, by amoxicillin-clavulanate (AC; 875 mg given orally every 12 hours). In the clinically evaluable population, therapeutic equivalence was demonstrated between the levofloxacin and TC/AC regimens (success rates of 84.1% and 80.3%, respectively). In the microbiologically evaluable population, the overall rate of eradication was 83.7% in the levofloxacin treatment group and 71.4% in the TC/AC treatment group (95% confidence interval, -24.3 to -0.2). Both levofloxacin and TC/AC were well tolerated. These data demonstrate that levofloxacin (750 mg once per day) is safe and at least as effective as TC/AC for complicated SSSIs.

Assessment of two penicillins plus beta-lactamase inhibitors versus cefotaxime in treatment of murine Klebsiella pneumoniae infections.

The in vivo efficacies of piperacillin, piperacillin plus tazobactam, ticarcillin, ticarcillin plus clavulanic acid, piperacillin plus clavulanic acid, and cefotaxime were compared in a mouse model of pneumonia induced by the SHV-1 beta-lactamase-producer Klebsiella pneumoniae. Each antibiotic was injected either once intraperitoneally at 24 h postinfection or at repeated times during 24 h. The efficacies of the drugs and therapeutic protocols were assessed by counting viable bacteria recovered from the lungs of mice sacrificed at selected times. No emergence of beta-lactam-resistant organisms was detected. Ticarcillin at 300 mg/kg was ineffective. Repeated injections of piperacillin at 300 mg/kg, either alone or in combination with tazobactam (8:1), led to a significant decrease in bacterial counts, but this was followed by bacterial regrowth. The pharmacokinetic analysis demonstrated that this short-lasting antibacterial effect was not due to a failure of piperacillin and/or tazobactam to penetrate the lungs. The combinations of ticarcillin at 300 mg/kg plus clavulanic acid (15:1) and piperacillin at 300 mg/kg plus tazobactam (4:1) were proven to be effective in that they decreased the bacterial burden in the lungs from 10(5) to < 10(3) CFU. This dose effect of tazobactam can be explained by its dose-dependent penetration in the lungs. Cefotaxime at 100 mg/kg and the combination of piperacillin (slightly hydrolyzed by SHV-1) at 300 mg/kg plus clavulanic acid (15:1) led to the best efficacy. Both of these treatments induced a decrease in bacterial counts of nearly 4 log10 units. The survival rates correlated with the quantitative measurements of in vivo bacterial killing. These experimental results obtained from the restricted animal model used here may help in the design of further protocols for clinical trials.

In vitro evaluation of newer beta-lactam antibiotics against gram negative bacilli isolated from neutropenic patients.

The in-vitro susceptibility pattern to newer beta lactams namely Ticer/Clav, Azlocillin, Piperacillin and Imipenem was determined with 50 clinical strains isolated from neutropenic patients with strains isolated from neutropenic patients with sepsis, with an objective of evolving a strategy for empirical antibiotic therapy for febrile neutropenic patients. The MIC90 value for Imipenem for the Gram negative bacilli tested, other than Pseudomonas was < 0.25 mcg/ml therapy revealing a high degree of susceptibility, while for Ps. aeruginosa and related species MIC50 and MIV90 values were 2.0 and 64.0 micrograms/ml respectively. A comparatively lower degree of susceptibility was found among Gram negative bacilli included in the study to ticar/clavu, azlocillin and piperacillin indicating a moderate degree of resistance to these antibiotics. The data from this study suggests that (i) Ureidopenicillins with an aminoglycoside should be effective therapy for proven Pseudomonas and other Gram negative sepsis in febrile neutropenic patients. (ii) Imipenem would be the antibiotic of choice in Gram negative bacterial sepsis in febrile neutropenic patients where the organism is resistant to cephalosporins and ureidopenicillins.

Comparative efficacies of ticarcillin, ticarcillin/clavulanic acid, piperacillin and cefoxitin against polymicrobial infections in mice caused by Escherichia coli and Bacteroides fragilis.

A model of localised abscess formation was used to establish mixed infections caused by Escherichia coli and Bacteroides fragilis. The beta-lactamase producing, ticarcillin-resistant strains E. coli E96 and B. fragilis VPI 8708 were used to produce one infection, and in another infection, a beta-lactamase hyperproducing strain E. coli 41548 was combined with a ticarcillin-susceptible strain, B. fragilis B3. Treatment, at doses producing clinically achievable concentrations in mouse serum, began 1 h after inoculation, and continued three times daily for four days. Bacterial numbers in infected tissue were measured at intervals. Against both infections, ticarcillin was ineffective in preventing bacterial growth and abscess formation in all mice. Piperacillin prevented abscess formation in 60% of the mice infected with E. coli E96/B. fragilis VPI 8708, and in 40% of those in the E. coli 41548/B. fragilis B3 group. Therapy with ticarcillin/clavulanic acid or cefoxitin reduced the number of both organisms at the site of infection, and thus prevented abscess formation in 100% treated animals.

Role of sodium in protection by extended-spectrum penicillins against tobramycin-induced nephrotoxicity.

Salt depletion is known to potentiate aminoglycoside nephrotoxicity, while salt replacement attenuates it. Recent studies have shown that ticarcillin protects against tobramycin and gentamicin nephrotoxicity. It has been suggested that this protection is due to an interaction between ticarcillin and the aminoglycoside. However, it can also be explained by the salt load associated with ticarcillin administration. This study was conducted to examine this question. Tobramycin was administered to eight groups of rats at 100 mg/kg per day intraperitoneally for 10 days. Group 1 rats were salt depleted, while group 2 rats were on a normal salt diet. Rats in groups 3 through 8 were also salt depleted but received, in addition, the following interventions intraperitoneally: group 3, ticarcillin, 300 mg/kg per day (0.37 to 0.39 meq of Na supplement per day); group 4, ticarcillin, 300 mg per day (1.56 meq of Na supplement per day); group 5, ticarcillin, 300 mg/kg per day, and NaCl supplement (1.17 to 1.19 meq/day), resulting in a total load of 1.56 meq/day; group 6, piperacillin, 400 mg/day (0.76 meq of Na supplement per day and equimolar to the ticarcillin dose [300 mg/day] in group 4 rats); group 7, piperacillin, 400 mg/day, and NaCl supplement (0.8 meq/day) for a total Na load of 1.56 meq/day; and group 8, 1.56 meq of Na per day as NaCl. Rats in groups 2, 4, 5, 7, and 8, which received a normal salt diet or its equivalent Na supplement, had no significant change in creatinine clearance (CLCR) over the 10-day period. The remaining groups sustained significant reductions in CLCR, as follows: group 1, -53.0% (P < 0.05); group 3, -66.2% (P < 0.05); group 6, -79.8% (P < 0.05). A positive correlation was found between the concentration of tobramycin in the kidneys and the percent change in CLCR at the end of the study. Concentrations of drugs in plasma were highest in group 1 rats, lowest in the rats in groups in which protection was observed, and moderately elevated in the remaining groups of rats. The results of this study suggest the following: (i) that the protective effect of ticarcillin against tobramycin nephrotoxicity is secondary to the obligatory sodium load associated with it, (ii) pharmacokinetic and pharmacodynamic interactions between salt and tobramycin are proposed to explain this effect, (iii) the nephrotoxicity of tobramycin is probably related to the degree of accumulation of the drug in the kidney, and (iv) an in vivo interaction between tobramycin and ticarcillin does not contribute to the protective effect of the penicillin but may influence concentrations in plasma, especially under conditions of severe renal impairment.

Ticarcillin/clavulanate in severe infections in patients with varying renal function.

The therapeutic efficacy of ticarcillin/clavulanate was assessed in 71 patients with severe infections: 38 acute pyelonephritis, 16 septicaemia and 19 miscellaneous infections. The patients were classified according to their renal function in: Group A, normal (16 cases); B, mild renal impairment (RI) with creatinine clearance (Clcr) between 80 and 40 ml/min (18 cases); C, moderate RI with Clcr between 40 and 15 ml/min (12 cases); D, severe RI with (Clcr) between 15 and 5 ml/min (13 cases) and E, terminal with (Clcr) less than 5 ml/min (12 cases). A total of 105 microorganisms (48.6% resistant to ticarcillin): 31 Pseudomonas aeruginosa, 18 Escherichia coli, 21 other Enterobacteriaceae, 2 Haemophilus influenzae, 10 Bacteroides spp., 14 enterococci, 8 staphylococci and 1 streptococcus, were isolated. All except six Ps. aeruginosa were sensitive to ticarcillin/clavulanate, using 75:10 microgram discs. Bacteriological eradication was obtained in 97% of the cases on the third day and at the end of treatment, and in 82% of the cases after one month. In all the assessable cases, the clinical symptoms disappeared on the third day except in one patient who developed a resistant strain (Klebsiella oxytoca). The wide range of bacteria assessed and the clinical-bacteriological success rates demonstrated that the ticarcillin/clavulanate combination had an efficacy/safety profile that could be considered excellent. Tolerance was good and side effects were not observed. This study confirms the practical efficacy of the recommended dosages derived from our previous kinetic studies in RI.

Pharmacokinetics of intravenously and intramuscularly administered ticarcillin and clavulanic acid in foals.

Serum concentrations of ticarcillin and clavulanic acid were measured in healthy foals (2 to 6 months old) given the drugs in combination by intravenous and intramuscular routes of administration. Five foals were administered 50 mg of ticarcillin/kg of body weight and 1.67 mg of clavulanic acid/kg, IV. Five foals were administered 100 mg of ticarcillin/kg and 3.33 mg of clavulanic acid/kg, IV, and 4 of those 5 were given the same combined dose IM. The elimination half-life of ticarcillin for intravenous administration was 0.83 hour for the low dosage and 0.96 hour for the high dosage. After intramuscular administration, the half-life of elimination was 2.9 hours, with bioavailability of 54.6%. For IV administered clavulanic acid, the elimination half-life was 0.65 hour for the low dosage and 0.74 hour for the high dosage. After intramuscular administration, the elimination half-life was 0.92 hour, and bioavailability was 68.1%. A combined dosage, 50 mg of ticarcillin/kg and 1.67 mg of clavulanic acid/kg, given every 6 hours is recommended.

Pseudomonas peritonitis in neutropenic rats treated with amikacin, ceftazidime and ticarcillin, alone and in combination.

Peritonitis in neutropenic rats, caused by a strain of Pseudomonas aeruginosa resistant to amikacin and ticarcillin alone but susceptible to ceftazidime and combinations of amikacin with ticarcillin, amikacin with ceftazidime and ticarcillin with ceftazidime, was investigated. Four hours after a bacterial challenge with a LD70 intraperitoneal dose of P. aeruginosa (1.5 X 10(8) cfu/ml), either amikacin, ticarcillin, ceftazidime, amikacin-ticarcillin, amikacin-ceftazidime, or ticarcillin-ceftazidime was administered at dosing intervals that mimicked the serum concentrations of the drugs found in humans after therapeutic doses. When the serum concentrations did not exceed the MIC, as occurred with amikacin, no difference in survival was observed compared with controls. All other regimens resulted in animal survival during the treatment. When therapy was stopped only those regimens resulting in serum concentrations above the MBC were effective (amikacin-ticarcillin, amikacin-ceftazidime, ticarcillin-ceftazidime). The recovery of viable bacteria from the peritoneum agreed well with mortality.

Efficacy of single-agent therapy with azlocillin, ticarcillin, and amikacin and beta-lactam/amikacin combinations for treatment of Pseudomonas aeruginosa bacteremia in granulocytopenic rats.

The efficacy of azlocillin, ticarcillin, and amikacin as single agents and the penicillin/amikacin combinations for treatment of Pseudomonas aeruginosa bacteremia during cyclophosphamide-induced severe neutropenia in a rat model were assessed. Equivalent antibiotic dosing was based on the time rat serum antibiotic levels were above the minimal bactericidal concentration for the challenge organism. Antibiotic therapy was administered for 62 hours after bacterial challenge. Antimicrobial efficacy was based on the rate of bacteremia, the emergence of resistant organisms during therapy, life-table survival analysis, and rat survival seventy-two hours after bacterial challenge. For infection with a P. aeruginosa strain susceptible to all study antibiotics, therapy with azlocillin and ticarcillin (given so as to be equipotent) were equivalent, as judged by bacteremia rates or rat survival. However, combination therapy prevented the emergence of organisms resistant to azlocillin, but not to ticarcillin. Amikacin-containing combinations were more effective than single-agent regimens.

Activity of penicillin or ticarcillin in combination with clavulanic acid in the treatment of experimental intra-abdominal abscess.

The combination of clavulanic acid (CA) with penicillin or ticarcillin was evaluated in a rat intra-abdominal abscess model. Gelatin capsules filled with a mixture of Bacteroides fragilis and Escherichia coli were implanted intraperitoneally in male Wistar rats. Four different groups of animals with appropriate controls were treated with penicillin or ticarcillin alone or in combination with CA. The treatment was started either immediately or delayed for 48 h after peritoneal inoculation. The therapeutic regimen was given for ten days at 8-hourly intervals. The mortality rate decreased to almost one-half when antibiotic therapy was started within 6 h. Seventy-nine to 89% of animals were cured when treated with ticarcillin in combination with CA showing that ticarcillin + CA was the most effective regimen of those tested in the treatment of experimental intra-abdominal abscess of rats caused by Bact. fragilis and E. coli.

A multicenter comparative trial of tobramycin and ticarcillin vs moxalactam and ticarcillin in febrile neutropenic patients.

During a multicenter prospective randomized trial in febrile neutropenic patients (neutrophil count, less than 1,000/cu mm), 103 episodes were treated with tobramycin sulfate plus ticarcillin disodium (TT) while 117 were treated with moxalactam plus ticarcillin disodium (MT). The majority of patients had an underlying diagnosis of leukemia (60%) and most (62.8%) had granulocyte counts of less than 100/cu mm at the start of therapy. The response rates for clinically or microbiologically documented episodes were 38 of 60 (55.1%) for TT and 38 of 64 (59.4%) for MT. The MT regimen appeared to be more effective for gram-positive infections (56% vs 33%) while TT appeared more effective for gram-negative infections (64% vs 40%). Nephrotoxicity attributable to study drugs occurred in only 2.3% of cases (one on each treatment arm). Prolongation of the prothrombin time was observed in only six of 78 (7.7%) in the TT arm as compared with 39 of 103 (38%) in the MT arm. Neither regimen was adequate for the unusually high frequency of gram-positive pathogens seen during this study.

Serum bactericidal activity as a therapeutic guide in severely granulocytopenic patients with gram-negative septicemia.

The peak and trough levels of bactericidal activity of the serum of 74 severely granulocytopenic patients (less than or equal to 500 polymorphonucleates per microliter) with hematologic malignancies and Gram-negative septicemia were measured using the patient's infectious organism and serum containing the given antibiotics. When the peak titer of bactericidal activity in the serum was greater than 1:8 the septicemia was cured in more than 90% of the cases. However, in order to achieve a satisfactory rate of cure, patients with less than 100 polymorphonucleates/microliter required higher peak levels than patients with 100-500 polymorphonucleates/microliter. Serum bactericidal activity was influenced by the in vitro susceptibility of the offending pathogen and by the presence of in vitro synergism between the given antibiotics. These two variables showed a correlation with the clinical outcome that proved to be increasing with the degree of granulocytopenia. Furthermore, synergistic combination of the antibiotics appeared essential when the in vitro susceptibility shown by the offending pathogen was moderate. These data suggest (i) that determination of the bactericidal activity of the serum may prove to be a useful method to predict the clinical outcome in severely granulocytopenic patients with Gram-negative septicemia; and (ii) under the same conditions, antibiotic combinations that have demonstrable in vitro synergy against the offending pathogen should be given the utmost consideration.

Addition of rifampin to ticarcillin-tobramycin combination for the treatment of Pseudomonas aeruginosa infections: assessment in a neutropenic mouse model.

The efficacy of ticarcillin (100 mg/kg), tobramycin (1 mg/kg), and rifampin (43 and 7.2 mg/kg) individually and in combination was assessed in neutropenic mice infected with an LD90 of one of four Pseudomonas aeruginosa isolates. The study end point was survival at 120 hours after infection. Treatment with the triple combination, ticarcillin plus tobramycin plus rifampin (43 mg/kg), was significantly superior to the double combination of ticarcillin plus tobramycin (p less than 0.01). Although treatment with rifampin (43 mg/kg) alone yielded results similar to treatment with the triple combination in mice infected with three of the four isolates, rifampin-resistant mutants (minimal inhibitory concentration greater than 1000 micrograms/ml) of P. aeruginosa were frequently isolated from surviving mice (26% of mice sampled). In contrast, in mice treated with the triple combination, rarely were rifampin-resistant mutants isolated (3% of mice sampled). Rifampin alone was active against P. aeruginosa isolates only when peak serum concentrations of rifampin exceeded the rifampin minimal bactericidal concentration of the infecting isolate. The addition of rifampin to a "standard" therapy of antipseudomonal penicillin plus aminoglycoside may be useful in the treatment of serious P. aeruginosa infection.

[Role of azlocillin in the treatment of immunocompromised patients. Results of the EORTC (European Organization for Research on the Treatment of Cancer) study)]. / Place de l'azlocilline dans le traitement des malades immunodéprimés. Résultats de l'étude de l'E.O.R.T.C.

A multicentre clinical trial was organized by the International Antimicrobial Therapy Project Groups of the European Organisation for Research on the Treatment of Cancer (E.O.R.T.C.) to compare the effectiveness of three combinations of antibiotics (azlocillin + amikacin; cefotaxime + amikacin and ticarcillin + amikacin) in patients with malignant leukopenic and febrile diseases (polymorphonuclears less than 1000/mm3; temperature greater than 38.5 degrees C). Some 800 patients from 20 centres entered the study. Preliminary results in 421 assessable patients showed a 62% positive response rate. The response rate in patients with bacteraemia was twice as high in the azlocillin group than in the other groups, the difference being significant at p less than 0.02. This difference does not seem to be due to a distribution bias, since the responsible micro-organisms, the severity of granulopenia, the incidence of bacterial-resistant strains, etc., were similar in all three groups. Similarly, the death rate was 12% in the azlocillin-amikacin group as against 15% and 17% respectively in the other groups. It would appear from this trial that the azlocillin-aminoglycoside treatment is superior to the other antibiotic combinations tested in this category of patients.

A randomized study of tobramycin plus ticarcillin, tobramycin plus cephalothin and ticarcillin, or tobramycin plus mezlocillin in the treatment of infection in neutropenic patients with malignancies.

Two hundred twenty-five patients with 358 febrile episodes were treated with tobramycin and ticarcillin (TT), tobramycin and mezlocillin (TM), or tobramycin, ticarcillin and cephalothin (TTC). There were no statistically significant differences in the response rates for patients who were proven to have infection (67% with TT, 69% with TTC and 53% with TM). Patients were more often cured of their infection if their neutrophil count rose during therapy. In this study, the addition of cephalothin to TT did not increase the frequency of azotemia (10% and 12%, respectively). Although mezlocillin has a broader spectrum of activity in vitro than ticarcillin, it was not more efficacious when combined with tobramycin than ticarcillin plus tobramycin for the treatment of infections in neutropenic patients.