Piperacillin/tazobactam plus tobramycin versus ceftazidime plus tobramycin for the treatment of patients with nosocomial lower respiratory tract infection. Piperacillin/tazobactam Nosocomial Pneumonia Study Group

An open-label, randomized, comparative, multi-centre study was conducted at 25 centres in the USA and Canada to compare the safety and efficacy of piperacillin/tazobactam plus tobramycin with ceftazidime plus tobramycin in patients with lower respiratory tract infections. Piperacillin/tazobactam (3 g/375 mg) every 4 h or ceftazidime (2 g) every 8 h were administered i.v. for a minimum of 5 days. Tobramycin (5 mg/kg/day) given in divided doses every 8 h was administered to all patients. Patients with Pseudomonas aeruginosa isolated from respiratory secretions at baseline were to continue tobramycin for the duration of the study. Tobramycin could be discontinued in other patients after the baseline culture results were known. A total of 300 patients was randomized, 155 into the piperacillin/tazobactam group and 145 into the ceftazidime group. Of these, 136 patients (78 in the piperacillin/tazobactam group and 58 in the ceftazidime group) were considered clinically evaluable. Both groups were comparable for age, sex, duration of treatment and other demographic features. The clinical success rate in evaluable patients was significantly greater (P = 0.006) in the piperacillin/tazobactam treatment group (58/78; 74%) than in the ceftazidime group (29/58; 50%). Eradication of the baseline pathogen was significantly greater (P = 0.003) in the piperacillin/tazobactam group (66%) than in the ceftazidime group (38%). The clinical and bacteriological responses of those patients with nosocomial pneumonia were similar to the overall results. Twelve (7.7%) piperacillin/tazobactam-treated patients and 24 (17%) ceftazidime-treated patients died during the study (P = 0.03). Seven of the 24 deaths in the ceftazidime treatment group but only one of the 12 deaths in the piperacillin/tazobactam treatment group were directly related to failure to control infection. The majority of adverse events were thought by the investigator to be attributable to the patients' underlying disease and not drug related. In this study, piperacillin/tazobactam plus tobramycin was shown to be more effective and as safe as ceftazidime plus tobramycin in the treatment of patients with nosocomial LRTI.     

Monotherapy with piperacillin/tazobactam versus combination therapy with ceftazidime plus amikacin as an empiric therapy for fever in neutropenic cancer patients

Between July 1993 and September 1996, 107 consecutive febrile episodes in 83 neutropenic cancer patients with a median age of 41 years were randomized to treatment either with piperacillin/tazobactam 4.5 g every 8 h i.v. or ceftazidime 2 g every 8 h plus amikacin 15 mg/kg i.v. per day. In the case of fever >38° C 48 h after initiation of the antibiotic therapy, vancomycin 500 mg every 6 h i.v. was added. The study population was at serious risk of a poor outcome, since 67% of the patients had leukemia or lymphoma, 19% of the febrile events occurred after autologous bone marrow or blood stem cell transplantation, the median total duration of neutropenia was 16 days, and the median neutrophil count at study inclusion was 0.09 × 10⁹/l. The two patient groups were comparable in terms of risk factors. Bacteremia was found in 37%, other microscopically documented infections in 16%, and clinically documented infections in 26% of the febrile episodes. Most (96) febrile episodes were evaluable for response. No significant difference was found between piperacillin/ tazobactam and ceftazidime plus amikacin in terms of success rate (81% versus 83%), empirical addition of vancomycin (42% versus 38%), median time to fever defervescence (3.3 versus 2.9 days) or median duration of antibiotic therapy (7.2 versus 7.4 days). No patient died from the infection. Both antibiotic regimens were well tolerated, the study treatment being stopped only in 1 patient because of toxicity (cutaneous allergy to piperacillin/tazobactam). On the basis of the 107 febrile events encountered, we conclude that piperacillin/tazobactam is a safe and effective monotherapy. To define the definitive value of piperacillin/ tazobactam as a monotherapy for febrile neutropenic patients a large randomized trial is warranted.     

Efficacy and tolerability of piperacillin/tazobactam versus ceftazidime in association with amikacin for treating nosocomial pneumonia in intensive care patients: a prospective randomized multicenter trial

OBJECTIVE: To compare clinical and bacteriological efficacy as well as tolerability of two regimens of broad-spectrum antibiotics (ceftazidime versus piperacillin/tazobactam) combined with amikacin in the treatment of nosocomial pneumonia in intensive care patients. DESIGN: Open label, prospective, multicenter, and randomized phase III clinical trial. SETTING: Medical or surgical intensive care units (ICUs) of nine acute-care teaching hospitals in Spain. PATIENTS AND PARTICIPANTS: One hundred and twenty-four ICU patients with nosocomial pneumonia and requiring mechanical ventilation were included. They were randomized to receive amikacin (15 mg/day divided into two doses) combined with either piperacillin (4 g every 6 h) and tazobactam (0.5 g every 6 h) (n = 88) or ceftazidime (2 g every 8 h) (n = 36). MEASUREMENTS AND RESULTS: The causative pathogen was determined in 60.2% of patients in the group of amikacin plus piperacillin/tazobactam and in 76.9% in the group of amikacin plus ceftazidime. A total of 94 bacterial organisms were isolated among which gram-negative bacilli predominated, Pseudomonas aeruginosa being the most frequent. Clinical response at the end of antibiotic therapy was considered satisfactory (cure and/or improvement) in 63.9% of patients in the amikacin plus piperacillin/tazobactam group and in 61.5% in the amikacin plus ceftazidime (odds ratio 1.1; 95% confidence interval 0.44-2.75). Eradication or presumptive eradication rates for each pathogen and for either gram-negative or gram-positive bacteria were similar in both antibiotic combinations (odds ratio 1.2; 95% confidence interval 0.39-3.66). A total of 21 adverse effects (23.9%) occurred in the amikacin plus piperacillin and tazobactam group and six (16.7%) in the amikacin plus ceftazidime group, thrombocytosis, renal dysfunction, and hepatic cytolysis being the most common. The efficacy and tolerability of the two therapeutic regimens were similar not only in the whole study population, but also in the subset of P. aeruginosa-related pneumonia (odds ratio 1; 95% confidence interval 0.08-13.37). CONCLUSIONS: Amikacin associated with either ceftazidime or piperacillin and tazobactam has shown comparable efficacy and tolerability in the treatment of ICU patients with nosocomial pneumonia.     

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.     

Simulation of antibiotic pharmacodynamic exposure for the empiric treatment of nosocomial bloodstream infections: a report from the OPTAMA program

OBJECTIVE: We developed a model to predict the pharmacodynamic exposure of antibiotics against bacteria commonly implicated in nosocomial bloodstream infections to determine which dosage regimens would provide the greatest likelihood of obtaining a bactericidal effect. METHODS: Pharmacodynamic exposures were simulated for 5000 subjects receiving standard doses of ceftazidime, cefepime, piperacillin/tazobactam, meropenem, imipenem, or ciprofloxacin. Exposures were indexed to the MICs of bacteria weighted by their prevalence in causing nosocomial bloodstream infections, derived from 2002 SENTRY data. Enterococci were excluded. MIC data were derived from the 2003 Meropenem Yearly Surveillance Test Information Collection resistance study. The probabilities of achieving bactericidal exposures (ie, target attainment) for each antibiotic regimen were compared. The effect of increasing prevalence of methicillin-resistant Staphylococcus aureus (MRSA) on attainment of bactericidal targets was tested. RESULTS: All dosage regimens except ciprofloxacin and ceftazidime 1 g q8h achieved >90% likelihood of bactericidal exposure. The rank order of target attainment was as follows: imipenem 500 mg q6h, 100.0%; imipenem 1 g q8h, 99.9%; cefepime 2 g q12h, 99.4%; meropenem 1 g q8h, 98.4%; cefepime 1 g q12h, 98.2%; piperacillin/tazobactam 3.375 g q6h, 97.9%; piperacillin/tazobactam 4.5 gq8h, 95.0%; ceftazidime 2 g q8h, 94.2%; ceftazidime 1 g q8h, 71.7%; ciprofloxacin 400 mg q8h, 63.3%; and ciprofloxacin 400 mg q12h,63.0%. Target attainments dropped to <90% for all agents when MRSA was modeled at > or =10% prevalence. CONCLUSIONS: The results of this model analysis suggest that standard doses of the carbapenems, piperacillin/tazobactam, and cefepime, and higher doses of ceftazidime, may provide optimal likelihood of achieving bactericidal exposure against pathogens implicated in nosocomial bloodstream infections, excluding MRSA and enterococci. When MRSA rates are > or =10%, therapy with an antibiotic that has activity against this phenotype should be empirically initiated.     

In vitro evaluation of the activity of two doses of Levofloxacin alone and in combination with other agents against Pseudomonas aeruginosa

P. aeruginosa is one of the most difficult to treat pathogens that generally requires combination therapy to prevent the development of resistance. This study evaluated the in vitro activity of two concentrations of levofloxacin (modeled for the 500 mg and 750 mg daily dose) in combination with ceftazidime, cefepime, piperacillin/tazobactam, imipenem, and tobramycin against P. aeruginosa. MICs and time-kill studies were performed against 12 non-duplicate clinical isolates of P. aeruginosa. The percent susceptible for levofloxacin, ceftazidime, cefepime, piperacillin/tazobactam, imipenem, and tobramycin were 67%, 58%, 58%, 67%, 75%, and 100%, respectively. Tobramycin was the most active single agent, killing and maintaining > or =99.9% killing over a 24 h period against all isolates. Levofloxacin 4 microg/mL(750 mg/day) alone reached 99.9% killing and maintain this killing over the time period more often than levofloxacin 2 microg/mL (500 mg/day). No combination was antagonistic and all combinations with tobramycin were indifferent. Overall, levofloxacin 2 microg/mL plus a beta-lactam was synergistic (65%) more often than levofloxacin 4 microg/mL combinations (46%). This was not unexpected due to the increased activity of levofloxacin 4 microg/mL. However, levofloxacin 4 microg/mL combinations maintained a > or =99.9% killing over the entire 24 h period more often than levofloxacin 2 microg/mL combinations (94% vs 83%). The findings from this work suggest that levofloxacin 750 mg/day in combination with another agent active against P. aeruginosa may prove to be clinically beneficial and superior to combinations using lower doses of levofloxacin. In vivo studies are needed to evaluate the clinical significance of these findings.     

Dynamic interactions of biofilms of mucoid Pseudomonas aeruginosa with tobramycin and piperacillin.

The dynamic interaction of planktonic and biofilm cells of mucoid Pseudomonas aeruginosa with tobramycin and piperacillin was investigated in a chemostat system. The results indicated that planktonic and young biofilm cells of the 2-day-old chemostat culture of P. aeruginosa were susceptible to killing by chemostat-controlled doses of either 250 micrograms of piperacillin per ml plus 5 micrograms of tobramycin per ml or 500 micrograms of piperacillin per ml plus 5 micrograms of tobramycin per ml. Complete eradication of the planktonic and young biofilm cells was observed after exposure of the cells to six chemostat-controlled doses of these antibiotic at 8-h intervals for 7 days. Regrowth of the organism was not observed after the termination of antibiotic therapy on day 7. A different picture was observed when antibiotic treatment was initiated on day 10 after inoculation. Viable old biofilm cells were reduced to approximately 20% after exposure to the chemostat-controlled doses of 500 micrograms of piperacillin per ml plus 5 micrograms of tobramycin per ml. Complete eradication of old biofilm cells could not be achieved, and regrowth of the organism occurred after the termination of antibiotic therapy. These data suggest that young biofilm cells of mucoid P. aeruginosa can be effectively eradicated with the combination of piperacillin and tobramycin, while old biofilm cells are very resistant to these antibiotics and eradication of old biofilm cells is not achievable with the chemostat-controlled doses of piperacillin and tobramycin used in this study.     

Post-antibiotic effect of ceftazidime, ciprofloxacin, imipenem, piperacillin and tobramycin for Pseudomonas cepacia.

The post-antibiotic effects (PAE) of ceftazidime, ciprofloxacin, imipenem, piperacillin and tobramycin were studied for ten strains of Pseudomonas cepacia isolated from patients with cystic fibrosis. Antibiotic concentrations used for exposure were either the MIC of each agent for the sensitive isolates or the recommended sensitivity breakpoint concentrations for the resistant isolates. After 2 h of exposure, cultures were rapidly diluted 1000-fold to eliminate the antibiotic. Out of the ten isolates, there were eight sensitive to ceftazidime, six to ciprofloxacin, six to imipenem, nine to piperacillin and five to tobramycin. All antibiotics tested demonstrated PAE for some isolates of P. cepacia, however, each antibiotic failed to produce a PAE for at least one isolate. The mean PAE was 1.35 h for ceftazidime, 2.38 h for ciprofloxacin, 2.39 h for imipenem, 2.16 h for piperacillin and 1.77 h for tobramycin. Imipenem demonstrated PAE of > or = 0.5 h for all sensitive isolates tested; ceftazidime, piperacillin, ciprofloxacin and tobramycin demonstrated PAE of > or = 0.5 h for 6/8, 8/9, 5/6 and 2/5 sensitive isolates, respectively. These data indicate that several antibiotics have significant (> or = 0.5 h) PAE for isolates of P. cepacia.     

Use of Monte Carlo simulation to assess the pharmacodynamics of beta-lactams against Pseudomonas aeruginosa infections in children: a report from the OPTAMA program

BACKGROUND: Assessing the likelihood of achieving bactericidal pharmacodynamic exposures against Pseudomonas aeruginosa with intravenous antimicrobial regimens would provide insights into the selection of empiric therapy in the pediatric population. OBJECTIVE: The objective of this study was to use pharmacodynamic modeling to determine the likelihood of various pediatric antibiotic regimens achieving bactericidal exposures against P aeruginosa in children. METHODS: Minimum inhibitory concentrations (MICs) were determined for meropenem (20 and 40 mg/kg q8h), imipenem (15 and 25 mg/kg q6h), ceftazidime (50 mg/kg q8h), cefepime (50 mg/kg q8h), and piperacillin/tazobactam (75 mg/kg q6h) against P aeruginosa isolates from 2 pediatric institutions. A 5000-patient Monte Carlo simulation was performed to predict attainment of pharmacodynamic targets against P aeruginosa for each of these regimens in a population of 10-year-olds. Optimal regimens were defined as those that had a > or =90% likelihood of attaining target exposures. RESULTS: At institution 1, high-dose imipenem, high-dose meropenem, and ceftazidime achieved bactericidal pharmacodynamic exposures (likelihood of target attainment: 94%, 92%, and 92%, respectively). No other regimen was associated with a high probability of attaining bactericidal exposure (low-dose imipenem, 87%; cefepime, 85%; low-dose meropenem, 84%; piperacillin/tazobactam, 60%). At institution 2, no regimen was associated with a high likelihood of attaining bactericidal exposure; the calculated probabilities were cefepime, 78%; ceftazidime, 65%; high-dose meropenem, 58%; high-dose imipenem, 57%; low-dose imipenem, 54%; low-dose meropenem, 47%; and piperacillin/tazobactam, 47%. A lack of agreement between attainment of bactericidal exposures and percent susceptibility was apparent for many of the regimens. CONCLUSIONS: Few regimens demonstrated a high likelihood of achieving bactericidal exposures against P aeruginosa at these institutions. Importantly, percent susceptibility overestimated attainment of the bactericidal target for some regimens, suggesting that further study is necessary in pediatric patients. The findings of this study highlight differences in target attainment and MIC distributions between institutions, emphasizing the importance of using institution-specific data when selecting empiric antimicrobial therapy.     

Effect of concomitant administration of piperacillin on the dispositions of netilmicin and tobramycin in patients with end-stage renal disease.

The effect of piperacillin administration on the dispositions of netilmicin and tobramycin was assessed in 12 chronic hemodialysis patients. Six subjects each received netilmicin (2 mg/kg) or tobramycin (2 mg/kg) alone and in combination with piperacillin (4 g every 12 h for four doses). Subjects also received a single dose of piperacillin (4 g) on a separate occasion. The serum concentration-versus-time profiles of netilmicin and tobramycin were biexponential. The terminal elimination half-life (t1/2 beta) of tobramycin was markedly reduced (59.62 +/- 25.18 [mean +/- standard deviation] versus 24.71 +/- 5.41 h) and total body clearance (CLP) was significantly increased in the presence of piperacillin (3.45 +/- 1.61 versus 7.16 +/- 1.64 ml/min). In contrast, the t1/2 beta (41.80 +/- 13.24 versus 40.07 +/- 10.37 h) and CLP (5.11 +/- 2.15 versus 5.55 +/- 2.32 ml/min) of netilmicin were not significantly altered when netilmicin was administered in combination with piperacillin. No change in the central or steady-state volume of distribution of netilmicin or tobramycin was observed. The disposition of piperacillin in hemodialysis patients was not altered in the presence of either aminoglycoside antibiotic. Although no adjustment in netilmicin dosing is required, tobramycin should be administered more frequently when given concomitantly with piperacillin to hemodialysis patients to avoid prolonged periods of subtherapeutic concentrations.     

Piperacillin, tazobactam, and gentamicin alone or combined in an endocarditis model of infection by a TEM-3-producing strain of Klebsiella pneumoniae or its susceptible variant.

The efficacy of tazobactam, a beta-lactamase inhibitor, in combination with piperacillin, was studied in vitro and in rabbit experimental endocarditis due to a Klebsiella pneumoniae strain (KpR) producing an extended-spectrum beta-lactamase, TEM-3, or its nonproducing variant (KpS). In vitro, piperacillin was active against KpS (MIC = 4 micrograms/ml, MBC = 8 micrograms/ml with 10(7)-CFU/ml inoculum) but not against KpR (MIC = MBC = 256 micrograms/ml). Tazobactam (1 microgram/ml) restored the activity of piperacillin against KpR (MIC = 2 micrograms/ml, MBC = 4 micrograms/ml). Gentamicin was active against both strains (MIC = 0.25 and 0.5 micrograms/ml for KpS and KpR, respectively). The piperacillin-tazobactam-gentamicin combination was synergistic in vitro. The piperacillin/tazobactam ratio in plasma and in vegetations was always lower than the 4/1 injected dose ratio. In vivo, piperacillin (300 mg/kg of body weight four times a day [QID]) was active against KpS but not against KpR. Tazobactam (75 mg/kg QID) was able to restore the in vivo effect of piperacillin (300 mg/kg QID) against KpR (-3.0 log10 CFU/g of vegetation versus that of controls). Gentamicin (4 mg/kg twice a day [BID]) was active against both strains. Compared with controls, the combination of gentamicin plus piperacillin against KpS (-5.6 log10 CFU/g of vegetation), and the gentamicin-piperacillin-tazobactam combination against KpR (-4.4 log10 CFU/g of vegetation) achieved the greatest decrease in bacterial counts in vegetations and were the only regimens that significantly increased the proportion of sterile vegetations. It is concluded that (i) tazobactam was able to restore the effect of piperacillin against a TEM-3 extended-spectrum Beta-lactamase-producing strain of K. pneumoniae, both in vitro and in a severe experimental infection with high inoculum, when used in a 4/1 piperacillin/tazobactam dose ratio; (ii) gentamicin alone was effective because of the high peak/MBC ratio in plasma; (iii) piperacillin-tazobactam-gentamicin, probably because of the effect of gentamicin in reducing bacterial inoculum in vivo, as stressed by the results obtained by piperacillin-gentamicin against KpS, may be the most effective regimen against KpR.     

Antimicrobial susceptibility of blood culture isolates of viridans streptococci: relationship to a change in empirical antibiotic therapy in febrile neutropenia

This study investigated the antibiotic susceptibilities of 67 isolates of viridans streptococci from 61 cases of bacteraemia in immunocompromised paediatric patients with malignancy. The majority of patients (87%) had received prior courses of empirical antibiotic therapy, which consisted of ceftazidime plus amikacin during period 1 and piperacillin/tazobactam plus amikacin during period 2. Susceptibility to vancomycin and quinupristin/dalfopristin was 100%. Susceptibility to beta-lactam antibiotics varied. For period 1, the geometric mean MICs of all beta-lactams tested against blood culture isolates (n = 31) exceeded those against isolates (n = 36) collected from blood after the change in empirical therapy (by 3.3-fold for ceftazidime, 2.8-fold for piperacillin/tazobactam and 1.6-fold for penicillin). The selection of a beta-lactam antibiotic for empirical therapy must be made with care, as repeated courses of certain agents may be more likely to select for viridans streptococci with diminished susceptibility.     

Combined imipenem/cilastatin and tobramycin therapy of multiresistant Pseudomonas aeruginosa in cystic fibrosis

Ten patients with cystic fibrosis (CF) and chronic broncho-pulmonary Pseudomonas aeruginosa infection were given imipenem/cilastatin (100 mg/kg/day) in combination with tobramycin (15 mg/kg/day). Forced vital capacity and forced expiratory volume in the first second improved significantly in nine out of ten patients, and most of the patients improved clinically. P. aeruginosa was not eradicated in any patient and resistance against imipenem developed in all patients during treatment. A concomitant increase in MIC of piperacillin and ceftazidime occurred during treatment. In-vitro bactericidal synergy of imipenem and tobramycin was noted in 57% of pretreatment isolates. Seven patients complained of adverse reactions, mainly gastrointestinal, and treatment of three patients was discontinued after 5, 8, and 12 days of therapy, because of rash or nausea and vomiting. The side effects were considered to be due to imipenem/cilastatin. Because of the rapid development of imipenem resistance despite combination therapy, the high proportion of side effects, and the risk of induction of beta-lactam resistance, imipenem/cilastatin cannot be recommended for routine treatment of CF-patients with P. aeruginosa infection.     

Therapeutic efficacy of cefpiramide-ciprofloxacin combination in experimental Pseudomonas infections in neutropenic mice

The therapeutic efficacy of cefpiramide and ciprofloxacin alone and in combination was investigated and compared with that of ticarcillin plus tobramycin against pseudomonal infections in mice made neutropenic by administration of cyclosphosphamide. Therapy with cefpiramide plus ciprofloxacin was significantly more effective than that by either antibiotic alone. These results were consistent with in-vitro synergistic effects. At a higher dose of ciprofloxacin (4 mg/kg) plus cefpiramide (50 mg/kg), the combination therapy protected all neutropenic mice from fatal bacteraemia, and was more protective than ticarcillin (200 mg/kg) plus tobramycin (1 mg/kg). The peak serum concentration of cefpiramide in infected neutropenic mice was 51 mg/l when they were given 50 mg/kg subcutaneously. Ciprofloxacin attained a peak serum concentration of 1.2 mg/l and a serum half-life of 34 min.     

Treatment of neutropenic infection: a randomized trial comparing latamoxef (moxalactam) with cephradine plus tobramycin

Sixty neutropenic patients with infection were studied in a randomized trial comparing treatment with latamoxef (moxalactam) alone or with cephradine and tobramycin. The two treatment groups were comparable in respect to their clinical sites of infection, degree of neutropenia underlying malignancy, and organisms. Forty-two bacterial isolates were obtained from various clinically infected sites. All but two of these isolates were sensitive to latamoxef (30 highly sensitive, ten moderately sensitive). In contrast 29 of the isolates were resistant to cephradine and eight were resistant to both cephradine and tobramycin. Control of infection was achieved in 72% of patients treated with latamoxef and 55% treated with cephradine plus tobramycin. Latamoxef appears to be an effective antibiotic for the treatment of neutropenic patients with infection.     

Piperacillin-tazobactam is more effective than ceftriaxone plus gentamicin in febrile neutropenic patients with hematological malignancies: a randomized comparison

GOALS: Efficacy and costs of empirical antibacterial therapy in febrile neutropenic patients are important issues. Several strategies have been reported to be similarly effective: monotherapy with cefepime, ceftazidime or a carbapenem or duotherapy with an antipseudomonal beta-lactam antibiotic or ceftriaxone in combination with an aminoglycoside. Piperacillin-tazobactam monotherapy is promising, but its role in this setting still has to be defined. PATIENTS AND METHODS: Of 212 consecutive febrile episodes in 130 neutropenic patients with hematological malignancies randomized to receive either piperacillin-tazobactam (4.5 g every 8 h; group A) or ceftriaxone (2 g once daily plus gentamicin 5 mg/kg once daily; group B), 183 episodes (98 group A, 85 group B) were evaluable for response. RESULTS: Defervescence within 72 h without modification of the antibiotic therapy was achieved in 56/98 episodes (57.1%) in group A and in 30/85 (35.3%) in group B (P=0.0047). If fever persisted, teicoplanin plus gentamicin (group A) or teicoplanin plus ciprofloxacin (group B) were added. All patients still febrile then received meropenem, teicoplanin and amphotericin B. With these modifications of antibiotic therapy, 89.8% of patients in group A had responded at 21 days but only 71.8% in group B (P=0.005). The mean total antibiotic drug cost in group A was only 39.4% of that in group B (euro 445 versus euro 1129; P=0.010). CONCLUSION: Piperacillin-tazobactam monotherapy is significantly more effective and cost-efficient than ceftriaxone plus gentamicin as first-line therapy in febrile neutropenic patients with hematological malignancies.     

In vitro comparison of cefpirome and four other beta-lactam antibiotics alone and in combination with tobramycin against clinical isolates of Pseudomonas aeruginosa

In vitro susceptibility studies of cefpirome versus cefotaxime, ceftazidime, imipenem, and piperacillin alone and in combination with tobramycin were performed against 153 clinical isolates of Pseudomonas aeruginosa from four medical centers. The minimal inhibitory concentration (MIC) for each antibiotic alone was determined by a standardized dilution method. Antibiotic combination studies were performed using a modified checkerboard technique. Cefpirome alone was more active (MIC90 64 micrograms/ml) than piperacillin (MIC90 128 micrograms/ml) or cefotaxime (MIC90 256 micrograms/ml) but less active than imipenem (MIC90 2 micrograms/ml) or ceftazidime (MIC90 32 micrograms/ml). The addition of tobramycin reduced the MICs of all of the beta-lactam antibiotics except for imipenem. The MIC90 for cefpirome when combined with tobramycin was 8 micrograms/ml compared to 16 micrograms/ml for cefotaxime and piperacillin, 8 micrograms/ml for ceftazidime, and 4 micrograms/ml for imipenem. The combination of tobramycin and cefpirome proved to be additive or synergistic for 82% of the isolates (highest rate) compared to 31% with imipenem (lowest rate). The potent in vitro antipseudomonal activity of cefpirome alone and in combination with an aminoglycoside (tobramycin) suggests that this agent may play a useful role in the therapy of infections due to P. aeruginosa.     

Tobramycin once versus three times daily, given with penicillin G, to febrile neutropenic cancer patients in Norway: a prospective, randomized, multicentre trial

OBJECTIVES: Penicillin G with an aminoglycoside is the standard initial empirical treatment in febrile neutropenia in Norway. It has been argued that giving the aminoglycoside once daily to neutropenic patients with Gram-negative bacteraemia may be hazardous when penicillin G is the beta-lactam antibiotic. We questioned this argument and hypothesized that tobramycin once daily was as efficacious as three times daily. METHODS: We conducted a randomized prospective multicentre study, comparing the efficacy of tobramycin 6 mg/kg once (arm A) versus three times (arm B) daily, plus penicillin G 5 million IU x 4, in febrile neutropenic cancer patients. Primary outcome: modification of the antibiotic regimen. RESULTS: One hundred and seventy-four patients were evaluable for intention-to-treat analyses. One hundred and fifty-five patients had lymphoma or leukaemia as the underlying cancer diagnosis. In arm A, 35 of 88 patients and in arm B, 34 of 86 patients, that is 40% in both arms had no modification of the antibiotic regimen. No patients died while participating in the study. Upon modification of the antibiotic regimen, all patients were successfully treated. The increase in serum creatinine was modest and similar in the two treatment groups. CONCLUSIONS: When administered with penicillin G, tobramycin given once daily was as efficacious and safe as tobramycin given three times daily in cancer patients with febrile neutropenia in Norway, provided the regimen was modified according to the clinical response.     

Pharmacokinetics of ceftazidime, alone or in combination with piperacillin or tobramycin, in the sera of cancer patients.

We administered 2 g of ceftazidime intravenously every 8 h to cancer patients for the empiric therapy of febrile episodes. Ceftazidime was administered as monotherapy for patients with granulocyte counts in excess of 1,000/microliter. Febrile, neutropenic patients were randomized to also receive either piperacillin or tobramycin. The pharmacokinetic profile of ceftazidime during a steady-state dosing interval was ascertained in 21 patients. No differences were seen between groups for any of the pharmacokinetic parameters examined. As expected, the observed half-life was longer, the serum clearance was smaller, and the volumes of distribution were larger than in previously reported studies of volunteers. Serum concentrations remained above the MIC for inhibition of 90% of strains of the most common bacteremic pathogens seen in our cancer center for the entire 8-h dosing interval.     

Ciprofloxacin plus vancomycin versus ceftazidime plus gentamicin in the treatment of pneumonia in granulocytopenic patients with or without venous catheters. Short communication.

58 granulocytopenic patients with confirmed bronchopneumonia were divided retrospectively into two groups for this pilot study: group 1 included neutropenic patients with venous catheters who were treated with ciprofloxacin (CIP; 200-300 mg, i.v. b.i.d.) + vancomycin (VAN; 0.5-1 g, i.v. b.i.d.), and group 2, which included patients without venous catheters treated with ceftazidime (2 g, i.v. t.i.d.) + gentamicin (1 mg/kg, i.v. t.i.d.). Pneumonia was diagnosed clinically and radiologically in all patients; 92.3% in group 1 and 46.8% in group 2 were also microbially confirmed. Mixed infections were present in most patients. 3 of 26 patients (11.5%) in group 1 and 9 of 32 (20.1%) in group 2 did not recover while 88.5% in group 1 and 71.9% in group 2 recovered. CIP + VAN seems to be more effective in treating pneumonia in neutropenic patients, with only 1 patient in the group suffering an adverse effect compared with 5 in group 2.