Piperacillin-tazobactam versus imipenem-cilastatin for treatment of intra-abdominal infections

Guidelines for Antibiotics Prescription in Critically Ill Patients

How to cite this article: Khilnani GC, Tiwari P, Mittal S, Kulkarni AP, Chaudhry D, Zirpe KG, et al. Guidelines for Antibiotics Prescription in Critically Ill Patients. Indian J Crit Care Med 2024;28(S2):S104-S216.

Contradictory Recommendation in the Guideline for Antibiotic Prescription

How to cite this article: Das PK, Nath SS, Parashar S. Contradictory Recommendation in the Guideline for Antibiotic Prescription. Indian J Crit Care Med 2024;28(7):713-714.

Carbapenem Antibiotics Versus Other Antibiotics for Complicated Intra-abdominal Infections: a Systematic Review and Patient-Level Meta-analysis of Randomized Controlled Trials (PROSPERO CRD42018108854)

BACKGROUND

The treatment of complicated intra-abdominal infections remains a challenge. Both optimal medical and surgical therapy (i.e., source control) are needed to achieve low mortality and morbidity. The objective of this systematic review and meta-analysis is to determine the impact of carbapenem antibiotic therapy compared to other antibiotics in complicated intra-abdominal infections (secondary peritonitis) with an emphasis on mortality and postoperative complications.

METHODS

A systematic literature search from PubMed/Medline and Web of Science databases was carried out. The last search was conducted in August 2022. PRISMA guidelines were followed. Pre-defined outcomes were mortality, treatment success, treatment failure, and adverse events.

RESULTS

Ten randomized controlled trials, published from 1983 to 2013 with a total of 2377 patients (1255 patients in the carbapenem antibiotics group and 1122 in the control group), were identified. A meta-analysis comparing patients undergoing carbapenem antibiotic therapy and patients receiving other antibiotics was performed. No significant difference regarding mortality (OR 1.19, 95% CI [0.79; 1.82], p = 0.40), treatment success (OR 1.17, 95% CI [0.72; 1.91], p = 0.53), and treatment failure (OR 0.84, 95% CI [0.48; 1.45], p = 0.52) was observed. Carbapenem therapy was associated with fewer adverse events compared to therapy with other antibiotics (OR 0.79, 95% CI [0.65; 0.97], p = 0.022).

CONCLUSION

There is currently no evidence that carbapenem antibiotics are superior in terms of mortality, and success or failure for the treatment of complicated intra-abdominal infections (secondary peritonitis). The rate of adverse events is lower under carbapenem therapy compared to control antibiotics.

TRIAL REGISTRATION

PROSPERO 2018 CRD42018108854.

The efficacy and safety of eravacycline compared with current clinically common antibiotics in the treatment of adults with complicated intra-abdominal infections: A Bayesian network meta-analysis

Background

Eravacycline is a novel, fully synthetic fluorocycline antibiotic for the treatment of adults with complicated intra-abdominal infections (cIAIs). However, the efficacy and safety of eravacycline compared with current clinically common antibiotics remain unknown.

Objective

This study aims to compare the efficacy and safety of eravacycline and other clinically common antibiotics in China, including tigecycline, meropenem, ertapenem, ceftazidime/avibactam+metronidazole, piperacillin/tazobactam, imipenem/cilastatin, and ceftriaxone+metronidazole, for the treatment of adults with cIAIs and to provide a reference for clinical choice.

Methods

The PubMed, Embase, Cochrane Library, and ClinicalTrials.gov databases were electronically searched to collect clinical randomized controlled studies (RCTs) comparing different antibiotics in the treatment of patients with cIAIs from inception to June 1, 2021. Two reviewers independently screened the literature, extracted data, and evaluated the risk of bias in the included studies.

Results

A total of 4050 articles were initially retrieved, and 25 RCTs were included after screening, involving eight treatment therapies and 9372 patients. The results of network meta-analysis showed that in the intention-to-treat (ITT) population, the clinically evaluable (CE) population, and the microbiologically evaluable (ME) population, the clinical response rate of eravacycline was not significantly different from that of the other 7 therapies (P > 0.05). In terms of microbiological response rate, eravacycline was significantly better than tigecycline [tigecycline vs. eravacycline: RR = 0.82, 95%CI (0.65,0.99)], and there was no significant difference between the other 6 regimens and eravacycline (P > 0.05). In terms of safety, the incidence of serious adverse events, discontinuation rate, and all-cause mortality of eravacycline were not significantly different from those of the other 7 treatment therapies (P > 0.05).

Conclusion

Based on the evidence generated by the current noninferiority clinical trial design, the efficacy and safety of eravacycline for the treatment of adults with cIAIs are not significantly different from those of the other 7 commonly used clinical antibiotics in China. In terms of microbiological response rate, eravacycline was significantly better than tigecycline. In view of the severe multidrug-resistant situation in China, existing drugs have difficulty meeting the needs of clinical treatment, and the new antibacterial drug eravacycline may be one of the preferred options for the treatment of cIAIs in adults.

Diagnosis and Management of Intraabdominal Infection: Guidelines by the Chinese Society of Surgical Infection and Intensive Care and the Chinese College of Gastrointestinal Fistula Surgeons

The Chinese guidelines for IAI presented here were developed by a panel that included experts from the fields of surgery, critical care, microbiology, infection control, pharmacology, and evidence-based medicine. All questions were structured in population, intervention, comparison, and outcomes format, and evidence profiles were generated. Recommendations were generated following the principles of the Grading of Recommendations Assessment, Development, and Evaluation system or Best Practice Statement (BPS), when applicable. The final guidelines include 45 graded recommendations and 17 BPSs, including the classification of disease severity, diagnosis, source control, antimicrobial therapy, microbiologic evaluation, nutritional therapy, other supportive therapies, diagnosis and management of specific IAIs, and recognition and management of source control failure. Recommendations on fluid resuscitation and organ support therapy could not be formulated and thus were not included. Accordingly, additional high-quality clinical studies should be performed in the future to address the clinicians' concerns.

Pharmacokinetics and Pharmacodynamics of High-Dose Piperacillin-Tazobactam in Obese Patients

Background and Objective

Standard piperacillin–tazobactam (P-T) dosing may be suboptimal in obesity, but high-dose regimens have not been studied. We prospectively evaluated the pharmacokinetics and pharmacodynamics of standard- and high-dose P-T in obese adult inpatients.

Methods

Those receiving standard-dose P-T with BMI ≥ 30 kg/m² weighing 105–139 kg or ≥ 140 kg were given up to 6.75 g or 9 g every 6 h, respectively. Patients were monitored closely for safety. Elimination phase blood samples were drawn for 28 patients on standard and high doses to calculate the pharmacokinetic values using a one-compartment model. The likelihood of pharmacodynamic target attainment (100% fT > 16/4 mg/L) on various P-T regimens was calculated using each patient’s own pharmacokinetic values.

Results

Piperacillin and tazobactam half-lives ranged from 0.5–10.6 to 0.9–15.0 h, while volumes of distribution ranged from 13.6–54.8 to 11.5–60.1 L, respectively. Predicted dose requirements for target attainment ranged from 2.25 g every 6 h in hemodialysis patients to a 27 g/24-h continuous infusion in a patient with a short P-T half-life. An amount of 4.5 g every 6 h would have met the target for only 1/12 (8%) patients with creatinine clearance ≥ 80 mL/min and 13/28 (46%) for all enrolled patients. One patient (3%) experienced an adverse event deemed probably related to high-dose P-T.

Conclusion

Some patients required high P-T doses for target attainment, but dosing requirements were highly variable. Doses up to 6.75 g or 9 g every 6 h may be tolerable; however, studies are needed to see if high dosing, prolonged infusions, or real-time therapeutic drug monitoring improves outcomes in obese patients.

Clinical trial registration (clinicaltrials.gov)

NCT01923363.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13318-021-00677-1.

Carbapenems vs β-Lactam Monotherapy or Combination Therapy for the Treatment of Complicated Intra-abdominal Infections: Systematic Review and Meta-analysis of Randomized Controlled Trials

Background

Complicated intra-abdominal infections (cIAIs) result in significant morbidity, mortality, and cost. Carbapenem-resistant sepsis has increased dramatically in the last decade, resulting in infections that are difficult to treat and associated with high mortality rates. To prevent further antibacterial resistance, it is necessary to use carbapenem selectively. The objective of this study was to compare the effectiveness and safety of carbapenems vs alternative β-lactam monotherapy or combination therapy for the treatment of cIAIs.

Methods

The PubMed, Embase, Medline (via Ovid SP), and Cochrane library databases were systematically searched. We included randomized controlled trials (RCTs) comparing carbapenems vs alternative β-lactam monotherapy or combination therapy for the treatment of cIAIs.

Results

Twenty-two studies involving 7720 participants were included in the analysis. There were no differences in clinical treatment success (odds ratio [OR], 0.86; 95% confidence interval [CI], 0.71–1.05; I² = 35%), microbiological treatment success (OR, 0.88; 95% CI, 0.71–1.09; I² = 25%), adverse events (OR, 0.98; 95% CI, 0.87–1.09; I² = 17%), or mortality (OR, 0.96; 95% CI, 0.68–1.35; I² = 7%). Patients

treated with imipenem were more likely to experience clinical or microbiological failure than those treated with alternative β-lactam monotherapy or combination therapy.

Conclusions

No differences in clinical outcomes were observed between carbapenems and noncarbapenem β-lactams in cIAIs. Patients treated with imipenem were more likely to experience clinical or microbiological failure than those treated with alternative β-lactam monotherapy or combination therapy.

Guidelines for Antibiotic Prescription in Intensive Care Unit

How to cite this article: Khilnani GC, Zirpe K, Hadda V, Mehta Y, Madan K, Kulkarni A, Mohan A, Dixit S, Guleria R, Bhattacharya P. Guidelines for Antibiotic Prescription in Intensive Care Unit. Indian Journal of Critical Care Medicine 2019;23 (Suppl 1):1-63.

Co-administration of vancomycin and piperacillin-tazobactam is associated with increased renal dysfunction in adult and pediatric burn patients

Background

Burn patients are prone to infections which often necessitate broad antibiotic coverage. Vancomycin is a common antibiotic after burn injury and is administered alone (V), or in combination with imipenem-cilastin (V/IC) or piperacillin-tazobactam (V/PT). Sparse reports indicate that the combination V/PT is associated with increased renal dysfunction. The purpose of this study was to evaluate the short-term impact of the three antibiotic administration types on renal dysfunction.

Methods

All pediatric and adult patients admitted to our centers between 2004 and 2016 with a burn injury were included in this retrospective review if they met the criteria of exposition to either V, V/IC, or V/PT for at least 48 h, had normal baseline creatinine, and no pre-existing renal dysfunction. Creatinine was monitored for 7 days after initial exposure; the absolute and relative increase was calculated, and patient renal outcomes were classified according to the Kidney Disease Improving Global Outcomes (KDIGO) criteria depending on creatinine increases and estimated creatinine clearance. Secondary endpoints (demographic and clinical data, incidences of septicemia, and renal replacement therapy) were analyzed. Antibiotic doses were modeled in logistic and linear multivariable regression models to predict categorical KDIGO events and relative creatinine increase.

Results

Out of 1449 patients who were screened, 718 met the inclusion criteria, 246 were adults, and 472 were children. Between the study cohorts V, V/IC, and V/PT, patient characteristics at admission were comparable. V/PT administration was associated with a statistically higher serum creatinine, and lower creatinine clearance compared to patients receiving V alone or V/IC in adults and children after burn injury. The incidence of KDIGO stages 1, 2, and 3 was higher after V/PT treatment. In children, the incidence of KDIGO stage 3 following administration of V/PT was greater than after V/IC. In adults, the incidence of renal replacement therapy was higher after V/PT compared with V or V/IC. Multivariate modeling demonstrated that V/PT is an independent predictor of renal dysfunction.

Conclusion

Co-administration of vancomycin and piperacillin-tazobactam is associated with increased renal dysfunction in pediatric and adult burn patients when compared to vancomycin alone or vancomycin plus imipenem-cilastin. The mechanism of this increased nephrotoxicity remains elusive and warrants further scientific evaluation.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-017-1899-3) contains supplementary material, which is available to authorized users.

Pharmacokinetics of piperacillin-tazobactam in plasma, peritoneal fluid and peritoneum of surgery patients, and dosing considerations based on site-specific pharmacodynamic target attainment

Piperacillin-tazobactam (PIP-TAZ) is commonly used to treat intraabdominal infections; however, its penetration into abdominal sites is unclear. A pharmacokinetic analysis of plasma, peritoneal fluid, and peritoneum drug concentrations was conducted to simulate dosing regimens needed to attain the pharmacodynamic target in abdominal sites. PIP-TAZ (4 g-0.5 g) was intravenously administered to 10 patients before abdominal surgery for inflammatory bowel disease. Blood, peritoneal fluid, and peritoneum samples were obtained at the end of infusion (0.5 h) and up to 4 h thereafter. PIP and TAZ concentrations were measured, both noncompartmental and compartmental pharmacokinetic parameters were estimated, and a simulation was conducted to evaluate site-specific pharmacodynamic target attainment. The mean peritoneal fluid:plasma ratios in the area under the drug concentration-time curve (AUC) were 0.75 for PIP and 0.79 for TAZ, and the mean peritoneal fluid:plasma ratios in the AUC were 0.49 for PIP and 0.53 for TAZ. The mean PIP:TAZ ratio was 8.1 at both peritoneal sites. The regimens that achieved a bactericidal effect with PIP (time above minimum inhibitory concentration [MIC] >50%) at both peritoneal sites were PIP-TAZ 4.5 g twice daily for an MIC of 8 mg/L, as well as 4.5 g three times daily, and 3.375 g four times daily for an MIC of 16 mg/L. These findings clarify the peritoneal pharmacokinetics of PIP-TAZ, and help consider the dosing regimens for intraabdominal infections based on site-specific pharmacodynamic target attainment.

The Surgical Infection Society Revised Guidelines on the Management of Intra-Abdominal Infection

BACKGROUND

Previous evidence-based guidelines on the management of intra-abdominal infection (IAI) were published by the Surgical Infection Society (SIS) in 1992, 2002, and 2010. At the time the most recent guideline was released, the plan was to update the guideline every five years to ensure the timeliness and appropriateness of the recommendations.

METHODS

Based on the previous guidelines, the task force outlined a number of topics related to the treatment of patients with IAI and then developed key questions on these various topics. All questions were approached using general and specific literature searches, focusing on articles and other information published since 2008. These publications and additional materials published before 2008 were reviewed by the task force as a whole or by individual subgroups as to relevance to individual questions. Recommendations were developed by a process of iterative consensus, with all task force members voting to accept or reject each recommendation. Grading was based on the GRADE (Grades of Recommendation Assessment, Development, and Evaluation) system; the quality of the evidence was graded as high, moderate, or weak, and the strength of the recommendation was graded as strong or weak. Review of the document was performed by members of the SIS who were not on the task force. After responses were made to all critiques, the document was approved as an official guideline of the SIS by the Executive Council.

RESULTS

This guideline summarizes the current recommendations developed by the task force on the treatment of patients who have IAI. Evidence-based recommendations have been made regarding risk assessment in individual patients; source control; the timing, selection, and duration of antimicrobial therapy; and suggested approaches to patients who fail initial therapy. Additional recommendations related to the treatment of pediatric patients with IAI have been included.

SUMMARY

The current recommendations of the SIS regarding the treatment of patients with IAI are provided in this guideline.

Study of the comparative activity of piperacillin/tazobactam with currently available antibiotics against 8206 aerobic isolates

OBJECTIVES

To compare the activity of piperacillin-tazobactam with piperacillin and other parenterally administered antibiotics against aerobic Gram-negative bacilli and Gram-positive cocci isolated from across Canada, and to determine the prevalence of resistance mediated by extended-spectrum cephalosporinases.

METHODS

Sixty-one laboratories participated. Disk diffusion testing was performed in accordance with methods outlined by the National Committee for Clinical Laboratory Standards. Susceptibilities were performed on 8206 strains. Escherichia coli and Klebsiella pneumoniae with reduced susceptibilities to third-generation cephalosporins were screened for extended-spectrum beta-lactamases (ESBLs).

RESULTS

Piperacillin-tazobactam was active against 92% of the strains, piperacillin against 81% and ticarcillin-clavulanic acid against 88%. Few differences were observed in the relative susceptibility of strains from teaching or community hospitals, from different anatomic sites or from different regions of the country. Aerobic Gram-negative bacilli tested tended to be more susceptible to all the agents than was recently reported in a similar American study. Only 43% of Enterococcus faecium were susceptible to ampicillin and 42% to piperacillin piperacillin with and without tazobactam. Only two enterococcal strains were resistant to vancomycin, and 19 had intermediate zone sizes. Of the 10 strains of E coli and eight strains of K pneumoniae with reduced susceptibility to extended spectrum cephalosporins, only one demonstrated typical ESBL activity.

CONCLUSIONS

Canadian aerobic Gram-positive cocci and Gram-negative bacilli remain highly susceptible to many currently available antibiotics. The findings confirm a broad spectrum of activity of piperacillin-tazobactam and indicate that the pattern of susceptibility is quite uniform from different body sites, in both teaching and community hospitals, and across the country.

Cross-Canada survey of resistance of 2747 aerobic blood culture isolates to piperacillin/tazobactam and other antibiotics

OBJECTIVE

To compare the activity of piperacillin/tazobactam with that of other broad parenteral antibiotics against aerobic and facultative anaerobic blood culture isolates in a Canada-wide survey.

DESIGN

Fifty-eight laboratories in nine provinces each contributed up to 50 consecutive clinically significant aerobic and facultative anaerobic isolates for susceptibility testing.

SETTING

Participating hospitals included both tertiary care and community hospitals.

MATERIALS AND METHODS

Testing was performed in five regional centres by using the same microbroth dilution method, and results were interpreted according to National Commitee for Clinical Laboratory Standards M7-A3 and M100-S5 guidelines.

RESULTS

Piperacillin/tazobactam and imipenem were both active against more than 99% of the 1616 strains of Enterobacteriaceae species tested. The minimum inhibitory concentration of 90% of isolates (MIC(90)) of all Enterobacteriaceae species was 2 mg/L for piperacillin/tazobactam compared with 64 mg/L for piperacillin alone. Seventeen per cent of strains of Enterobacteriaceae species were susceptible to piperacillin/tazobactam but resistant to piperacillin. Piperacillin/tazobactam was highly active against Pseudomonas aeruginosa, inhibiting 99.1% of strains. MIC(90) was 8 mg/L. Nine per cent of P aeruginosa strains were not susceptible to imipenem. Most of these strains had a MIC of 8 mg/L, which falls in the intermediate category. Ninety-seven per cent of P aeruginosa were susceptible to ciprofloxacin and 97.3% to tobramycin. Ninety-six per cent of strains of Actinobacter species were susceptible to piperacillin/tazobactam, whereas only 76% of strains were susceptible to piperacillin alone. Overall, piperacillin/tazobactam was the most active agent tested; 98% of all strains were susceptible, followed closely by imipenem, to which 97.8% of strains were susceptible.

CONCLUSIONS

Aerobic blood culture isolates from Canadian centres continue to be highly susceptible to a variety of antibiotics. The broad spectrum of activity of piperacillin/tazobactam suggests that this combination should be considered for empirical treatment of sepsis while awaiting results of cultures and susceptibility testing.

Clinical review: balancing the therapeutic, safety, and economic issues underlying effective antipseudomonal carbapenem use

Antipseudomonal carbapenems have played a useful role in our antimicrobial armamentarium for 20 years. However, a review of their use during that period creates concern that their clinical effectiveness is critically dependent on attainment of an appropriate dosing range. Unfortunately, adequate carbapenem dosing is missed for many reasons, including benefit/risk misconceptions, a narrow therapeutic window for imipenem and meropenem (due to an increased rate of seizures at higher doses), increasingly resistant pathogens requiring higher doses than are typically given, and cost containment issues that may limit their use. To improve the use of carbapenems, several initiatives should be considered: increase awareness about appropriate treatment with carbapenems across hospital departments; determine optimal dosing regimens for settings where multidrug resistant organisms are more likely encountered; use of, or combination with, an alternative antimicrobial agent having more favorable pharmacokinetic, pharmacodynamic, or adverse event profile; and administer a newer carbapenem with lower propensity for resistance development (for example, reduced expression of efflux pumps or greater stability against carbapenemases).

Piperacillin-tazobactam penetration into human pancreatic juice

Piperacillin-tazobactam was administered as a single dose (4.5 g intravenous) to five patients with stabilized external pancreatic fistula. The penetration into pancreatic juice was prompt, and inhibitory concentrations were achieved and maintained for different periods (0.5 to 6 h) according to bacterial susceptibility and patients' characteristics. Piperacillin and tazobactam showed superimposable pharmacokinetics in both serum and pancreatic juice.

Carbapenems versus other beta-lactams in treating severe infections in intensive care: a systematic review of randomised controlled trials

Carbapenems have not been comprehensively compared in clinical trials with fourth-generation cephalosporins (4GC) and antipseudomonal penicillins (APP) in the treatment of severe infections (SI) and febrile neutropenia (FN). A systematic review of CENTRAL, EMBASE, MEDLINE and JICST-EPlus for randomised controlled trials was conducted to establish the currently available evidence. Database searching was supplemented by hand searching and contacting conference organisers. Searching was completed in November 2006 and no restriction was placed on the language of publication. Data were extracted on clinical response, bacteriologic response, all-cause mortality and adverse events. Of the 265 papers identified, 12 were appropriate for meta-analysis (four 4GC and eight APP). The results showed that carbapenems are associated with a significant reduction in all-cause mortality (relative risk 0.62, 95% confidence interval: 0.41 to 0.95; p=0.03) compared to APP in the treatment of SI, and withdrawals due to adverse events (RR 0.65, 95% CI: 0.45 to 0.96; p=0.03) are also less common. When compared in the treatment of FN, carbapenems are associated with a significant increase in clinical response during the initial 72 h of treatment (RR 1.37, 95% CI: 1.09 to 1.74; p=0.008) and bacteriologic response (RR 1.73, 95% CI: 1.03 to 2.89; p=0.04). For all other outcomes, including all comparisons with 4GC, there were no significant differences between treatments. The use of carbapenems rather than APP could reduce mortality and, by simplifying treatment decisions, reduce the time before patients receive appropriate antibiotic treatment. The currently available evidence is insufficient for distinguishing between carbapenems and 4GC.

Tigecycline in the treatment of complicated intra-abdominal and complicated skin and skin structure infections

Tigecycline, a glycylcycline related to the tetracycline class of antibiotics, represents a new option for the treatment of complicated intra-abdominal and complicated skin and skin structure infections. It displays favorable activity in vitro against the most common causative Gram-positive, Gram-negative and anaerobic pathogens. In addition, tigecycline demonstrates activity against drug-resistant pathogens such as methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, and organisms (such as Escherichia coli and Klebsiella pneumoniae) producing extended-spectrum beta-lactamases. Tigecycline lacks activity in vitro against Pseudomonas and Proteus spp. In randomized clinical trials, tigecycline administered intravenously twice daily has demonstrated efficacy similar to comparators for a variety of complicated skin and skin structure and complicated intra-abdominal infections. The potential for significant drug interactions with tigecycline appears to be minimal. Dosing adjustment is needed for patients with severe hepatic impairment. The predominant side effect associated with its use to date has been gastrointestinal intolerance (nausea and vomiting).

Tigecycline is efficacious in the treatment of complicated intra-abdominal infections

BACKGROUND

Empiric treatment of complicated intra-abdominal infections (cIAI) represents a clinical challenge because of the diverse bacteriology and the emergence of bacterial resistance. The efficacy and safety of tigecycline (TGC), a first-in-class, expanded broad-spectrum glycylcycline antibiotic, were compared with imipenem/cilastatin (IMI/CIS) in patients with cIAI.

METHODS

In this prospective, double-blind, phase 3, multinational trial, patients were randomly assigned to intravenous (i.v.) TGC (100 mg initial dose, then 50 mg every 12 h) or i.v. IMI/CIS (500/500 mg every 6 h) for 5-14 days. Clinical response was assessed at the test-of-cure (TOC) visit (14-35 days after therapy) for microbiologically evaluable (ME) and microbiologically modified intent-to-treat (m-mITT) populations (co-primary efficacy endpoint populations in which cure/failure response rates were determined).

RESULTS

Of 817 mITT patients (i.e., received > or = 1 dose of study drug), 641 (78%) comprised the m-mITT cohort (322 TGC, 319 IMI/CIS) and 523 (64%) were ME (266 TGC, 256 IMI/CIS). Patients were predominantly white (88%) and male (59%) with a mean age of 49 years. The primary diagnoses for the mITT group were complicated appendicitis (41%), cholecystitis (22%), and intra-abdominal abscess (11%). For the ME population, clinical cure rates at TOC were 91.3% (242/265) for TGC versus 89.9% (232/258) for IMI/CIS (95% CI -4.0, 6.8; P<0.001). Corresponding clinical cure rates within the m-mITT population were 86.6% (279/322) for TGC versus 84.6% (270/319) for IMI/CIS (95% CI -3.7, 7.5; P<0.001 for noninferiority TGC versus IMI/CIS). The most commonly reported adverse events for TGC and IMI/CIS were nausea (17.6% TGC versus 13.3% IMI/CIS; P=0.100) and vomiting (12.6% TGC versus 9.2% IMI/CIS; P=0.144).

CONCLUSIONS

TGC is efficacious in the treatment of patients with cIAIs and TGC met per the protocol-specified statistical criteria for noninferiority to the comparator, IMI/CIS.

Bacteriologic and therapeutic considerations in intra-abdominal surgical infections

The most important factor in the treatment of intra-abdominal infections are early diagnosis and prompt surgical intervention while antibiotics play a secondary role. The goals of surgical procedures should be to stop peritoneal contamination, to debride necrotic tissue, to remove debris and foreign bodies and to drain any pus collection. Antibiotics should be initiated before surgery and they must encompass both colonic aerobes and anaerobes including Bacteroides fragilis group but not necessary Enterococcus sp. Antibacterial agents with pure activity against anaerobes include chloramphenicol, clindamycin and the nitroimidazoles while ampicillin/sulbactam, amoxicillin/clavulanate, ticarcillin/clavulanate, cefoxitin, cefotetan, ceftizoxime imipenem/cilastatin, meropenem and some advanced quinolones like sparfloxacin, represent a single drug to cover both aerobic and anaerobic microflora. Although almost all clinical trials usually result in a 90% efficacy rate, the final outcome is dependant on the stage of the infection (early versus late), sepsis score, underlying diseases and the applied surgical procedures. On the other hand the choice of antibiotic(s) must be influenced by its toxicity, profiles local nosocomial susceptibility patterns, resistance inducing ability and price.

Intra-abdominal infections: considerations for the use of the carbapenems

Intra-abdominal infection remains a common and frequently severe medical condition, carrying with it significant morbidity and mortality. These infections are almost always polymicrobial in nature as they are caused by mixed aerobic/anaerobic intestinal flora. Despite substantial improvements in both the medical and surgical management of these infections over the last several decades, there remains an opportunity to further enhance the utilization of adjunctive antibiotic therapy. As a result of the epidemiology and the current resistance profile of the infecting pathogens, the carbapenems represent a class of antibiotics that are considered appropriate for the treatment of severe intra-abdominal infections. This review will discuss the classification and microbiology of these infections and emerging resistance in the pathogens of interest. The review also and focuses on the role of the carbapenems in the management of the constellation of diseases known as intra-abdominal infection.

Experience with the use of piperacillin-tazobactam in pediatric non-renal solid organ transplantation

Bacterial infection remains a major problem after solid organ transplantation (SOT), especially in children. Piperacillin-tazobactam (Pip-Tazo) is a beta-lactam-antibiotic combination with a broad spectrum of activity including gram-positive cocci as well as gram-negative rods, non-fermentative and anaerobic bacteria. The aim of this retrospective study was to critically review our experience with Pip-Tazo as perioperative prophylactic agent in pediatric non-renal SOT. Between 1993 and 2003 Pip-Tazo was used as initial perioperative prophylaxis in 45 pediatric patients who underwent a total of 49 transplants (36 liver-, seven cardiac-, two lung-, and four small bowel-) at our department. Median age of the children was 7.9 (range 0.5-18.1) years. A total of 34 rejection episodes following 27 transplants were diagnosed. During first hospitalization 44 infectious episodes were observed. Bacteria were responsible for 22 episodes including sepsis (n = 10), pneumonia (n = 5), wound infection (n = 4), urinary tract infection (n = 1), and clostridial colitis (n = 2). The isolated organisms were gram-positive cocci (n = 12), gram-negative rods (n = 3), non-fermentative bacilli (n = 4), and anaerobes (n = 3). Ten episodes were caused by Pip-Tazo resistant bacteria. Twenty-one of these infections were observed following antirejection therapy with pulse steroids. At later time points nine infectious episodes were successfully treated with a second course of Pip-Tazo. During follow up, eight patients died. Six deceased perioperatively: five from infection including aspergillosis (n = 4) and Pneumocystis jiroveci pneumonia (n = 1) and cerebrovascular bleeding (n = 1) and two children later on. At present 37 children (82%) are alive with well functioning graft after a median follow up of 39.2 (range 0.6-123.5) months. No severe side effects caused by Pip-Tazo were observed in any of the children. Pip-Tazo may be a suitable single agent for perioperative prophylaxis in pediatric non-renal solid organs recipients, however, a prospective comparative study is needed to make final conclusions.

Decision-Making Analysis for Selection of Antibiotic Treatment in Intra-Abdominal Infection Using Preference Measurements

BACKGROUND

Antimicrobial therapy of abdominal infections is important to the prognosis of affected patients. The choice of antimicrobial therapy must consider effectiveness, safety, cost, and antibiotic resistance, among numerous factors. However, in reality, decisions are made assuming bioequivalence between regimens, without considering the specific attributes of any particular regimen. The objective was to determine the best antibiotic regimen for patients with community-acquired abdominal infection on the basis of a decision analysis that included effectiveness as well as safety, measured as adverse effects.

METHODS

A decision tree was built using information from a systematic review of the literature on the effectiveness of antimicrobial regimens tested in randomized clinical trials (RCTs) and the frequency and severity of adverse effects. The quality of the articles was assessed with the Oxford criteria for RCTs. The main outcome was preferences reported by surgeons, measured on a numeric scale. Preferences were obtained using a standard survey that reported each adverse effect with its respective intensity, reversibility, sequelae, duration of symptoms, and necessity for change of antibiotic. Each of the surgeons had to assign a value blindly from 0 to 10, where 10 was the most severe. A sensitivity analysis was conducted varying the frequency of adverse effects.

RESULTS

The regimens analyzed were amikacin-metronidazole, amikacin-clindamycin, ciprofloxacin-metronidazole, ampicillin-sulbactam, ceftriaxone-metronidazole, piperacillin-tazobactam, and ertapenem. The perceived severity of adverse effects reported were: Acute neuromuscular blockade (8.0), severe allergic reaction (7.5), ototoxicity (7.4), nephrotoxicity (7.1), antibiotic-associated colitis (7.0), peripheral neuropathy (5.3), general neurological symptoms (4.9), gastrointestinal symptoms (3.1), and other general symptoms (2.6). Favored regimens were ceftriaxone-metronidazole (1.15), ampicillin-sulbactam (1.24), piperacillin-tazobactam (1.27) and ertapenem (1.28). These strategies dominated the other therapeutic schemes. Sensitivity analysis showed no changes in the dominance reported when the frequency of adverse effects was maintained in the known clinical range.

CONCLUSIONS

Antibiotic regimens that contain aminoglycosides are not bioequivalent to those without aminoglycosides when effectiveness and adverse effects are considered simultaneously. Antibiotic regimens that do not use aminoglycosides must be the first line of treatment for abdominal sepsis acquired in the community.

The Surgical Infection Society guidelines on antimicrobial therapy for intra-abdominal infections: an executive summary

The Surgical Infection Society last published guidelines on antimicrobial therapy for intra-abdominal infections in 1992 (Bohnen JMA, et al., Arch Surg 1992;127:83-89). Since then, an appreciable body of literature has been published on this subject. Therefore, the Therapeutics Agents Committee of the Society undertook an effort to update the previous guidelines, primarily using data published over the past decade. An additional goal of the Committee was to characterize its recommendations according to contemporary principles of evidence-based medicine. To develop these guidelines, the Committee carried out a systematic search for all English language articles published between 1990 and 2000 related to antimicrobial therapy for intra-abdominal infections. This literature was reviewed individually and collectively by the Committee, and categorized according to the type of study and its quality. Additional articles published prior to 1990 were also utilized when necessary. By a process of iterative consensus, the Committee developed provisional guidelines for antimicrobial therapy for intra-abdominal infections based on this evidence. Following extensive review by members of the Society, these guidelines were approved for publication in final form by the Council of the Surgical Infection Society. This executive summary delineates the Society's current recommendations for antimicrobial therapy of patients with intra-abdominal infections. Topics discussed include the selection of patients needing therapeutic antimicrobials, duration of antimicrobial therapy, acceptable antimicrobial regimens, and identification and treatment of higher-risk patients. Guidelines for patient selection and specific antimicrobial regimens were based on relatively good evidence, but those regarding optimal duration of therapy and treatment of higher-risk patients relied mostly on expert opinion, since there was a paucity of high-quality studies on those issues. Relevant areas for future investigation include the safety, convenience, and cost-effectiveness of available antimicrobial regimens for lower-risk patients, and better means for identifying and treating higher-risk patients with intra-abdominal infections.

The Surgical Infection Society guidelines on antimicrobial therapy for intra-abdominal infections: evidence for the recommendations

Revised guidelines for the use of antimicrobial therapy in patients with intra-abdominal infections were recently developed by the Therapeutic Agents Committee of the Surgical Infection Society (Mazuski et al., Surg Infect 2002;3:161-173). These were based, insofar as possible, on evidence published over the past decade. The objective of this document is to describe the process by which the Committee identified and reviewed the published literature utilized to develop the recommendations and to summarize the results of those reviews. English-language articles published between 1990 and 2000 related to antimicrobial therapy for intra-abdominal infections were identified by a systematic MEDLINE search and an examination of references included in recent review articles. If current literature with regard to a specific issue was lacking, relevant articles published prior to 1990 were identified. All prospective randomized controlled trials, as well as other articles selected by the Committee, were evaluated individually and collectively. Data with regard to patient numbers, types of infections, and results of interventions were abstracted. Studies were categorized according to their design, and all included trials were graded according to quality. On the basis of this evidence, the Committee formulated recommendations for antimicrobial therapy for intra-abdominal infections and graded those recommendations. After receiving comments from invited reviewers and the general membership of the Society, the guidelines were finalized and submitted to the Council of the Surgical Infection Society for approval. The final recommendations related to the selection of patients needing therapeutic antimicrobials, acceptable antimicrobial regimens, duration of antimicrobial use, and the identification and treatment of higher-risk patients. Although numerous publications pertaining to these topics were identified, but nearly all of the prospective randomized controlled trials represented comparisons of different antimicrobial regimens for the treatment of intra-abdominal infections. A few prospective trials evaluated the need for therapeutic antimicrobial therapy in patients with peritoneal contamination following abdominal trauma. The quality of these prospective trials was highly variable. Many did not limit enrollment to patients with complicated intra-abdominal infections, lacked blinding of treatment assignment, did not provide a complete description of the criteria used to determine therapeutic success or failure, failed to identify the reasons why patients were excluded from analysis, or did not include an intention-to-treat analysis. For many issues, no prospective randomized controlled trials were encountered, and guidelines had to be formulated using evidence from studies with historical controls or uncontrolled data, or on the basis of expert opinion

[Therapeutic management of peritonitis]

Antibiotherapy is a fundamental for the treatment of peritonitis. It may be used before surgery or as a complementary treatment after. Experimental models have demonstrated that infections are both aerobic and anaerobic. During the first stage, septicemic with a high death rate, the infection is due to enterobacteria, mostly Escherichia coli. Between D5 and D7 in surviving animals, there is a second stage with abscesses due to anaerobic bacteria, mostly Bacteroides fragilis. The antibiotic treatment must include these two types of bacteria in its spectrum. The role of Enterococcus faecalis is not clearly defined, but this bacterium must be taken into account in case of organ failure or associated septic shock. Treatment options for secondary peritonitis may be, according to severity, cefoxitin, an Augmentin + gentamycin combination, Tazocillin, or ertapenem. The reference treatment for nosocomial or tertiary peritonitis is the imipenem + amikacin combination. An antifungal treatment (fluconazole) is usually necessary, at least until the results of peritoneal fluid culture are available. The duration of treatment is quite variable, ranging from 48 h in less severe forms to 14 days.

Empiric Treatment of Nosocomial Intra-Abdominal Infections: A Focus on the Carbapenems

BACKGROUND

Serious nosocomial intra-abdominal infections are associated with high morbidity and mortality and represent a substantial drain on healthcare resources. Effective management of this type of infection requires the early use of appropriate, broad-spectrum empiric antimicrobial therapy. The consequences of delayed or inappropriate antimicrobial treatment can be severe-leading to an increased risk of death, re-operation, or prolonged hospitalization. Therefore, it is necessary to begin treatment as soon as possible with the most appropriate regimen, in terms of spectrum, timing, and duration.

METHODS

Review of pertinent English-language literature.

RESULTS

Serious nosocomial intra-abdominal infections require broad-spectrum coverage because of the wide range of possible pathogens, which include difficult-to-treat organisms such as Pseudomonas aeruginosa and Bacteroides spp., and resistant strains of Klebsiella spp., Escherichia coli, and methicillin-resistant Staphylococcus aureus acquired from the hospital flora. The early use of appropriate, broad-spectrum empiric antimicrobial therapy for treating high-risk patients with intra-abdominal infections is considered, and appropriate use of the carbapenems, meropenem, and imipenem/cilastatin, is described.

CONCLUSION

The carbapenems meropenem and imipenem/cilastatin have a spectrum of antimicrobial activity that covers the majority of expected pathogens, including anaerobes, as well as difficult-to-treat and resistant gram-negative strains. Early and appropriate use can reduce mortality and morbidity. Data from published clinical trials support the clinical effectiveness of these two carbapenems in intra-abdominal infections.

Antibiotic regimens for secondary peritonitis of gastrointestinal origin in adults

BACKGROUND

Secondary peritonitis is associated with a high mortality rate and if not treated successfully leads to development of abscesses, severe sepsis and multi-organ failure. Source control and adjunctive antibiotics are the mainstay of treatment. However, no conclusive evidence suggest that one antibiotic regimen is better than any other but at the same time have a lower toxicity.

OBJECTIVES

To ascertain the efficacy and adverse effects of different antibiotic regimens in treating intra-abdominal infections in adults. Outcomes were divided into primary (clinical success and effectiveness in reducing mortality) and secondary (microbiological success, preventing wound infection, intra-abdominal abscess, clinical sepsis, remote infection, superinfection, adverse reactions, duration of treatment required, effectiveness in reducing hospitalised stay, and time to defervescence).

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (Cochrane Library, Issue 4, 2004), MEDLINE (from 1966 to November 2004), EMBASE (from 1980 to November 2004) and Cochrane Colorectal Cancer Group specialised register SR-COLOCA. Bibliographies of identified studies were screened for further relevant trials.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials comparing different antibiotic regimens in the treatment of secondary peritonitis in adults were selected. Trials reporting gynaecological or traumatic peritonitis were excluded from this review. Ambiguity regarding suitability of trials were discussed among the review team.

DATA COLLECTION AND ANALYSIS

Six reviewers independently assessed trial quality and extracted data. Data collection was standardised using data collection form to ensure uniformity among reviewers. Statistical analyses were performed using the random effects model and the results expressed as odds ratio for dichotomous outcomes, or weight mean difference for continuous data with 95% confidence intervals.

MAIN RESULTS

Fourty studies with 5094 patients met the inclusion criteria. Sixteen different comparative antibiotic regimens were reported. All antibiotics showed equivocal comparability in terms of clinical success. Mortality did not differ between the regimens. Despite the potential high toxicity profile of regimens using aminoglycosides, this was not demonstrated in this review. The reason for this could be the inherent bias within clinical trials in the form of patient selection and stringency in monitoring drug levels.

AUTHORS' CONCLUSIONS

No specific recommendations can be made for the first line treatment of secondary peritonitis in adults with antibiotics, as all regimens showed equivocal efficacy. Other factors such as local guidelines and preferences, ease of administration, costs and availability must therefore be taken into consideration in deciding the antibiotic regimen of choice. Future trials should attempt to stratify patients and perform intention-to-treat analysis to allow better external validity.

Randomized Comparison of Piperacillin/Tazobactam Versus Imipenem/Cilastatin in the Treatment of Patients with Intra-abdominal Infection

OBJECTIVES

Treatment of intra-abdominal infections remains a challenge because of their polymicrobial nature and associated mortality risk. Broad-spectrum empiric coverage is usually required. This randomized study compared the efficacy and safety of intravenous piperacillin/tazobactam with those of intravenous imipenem/cilastatin in the treatment of 293 hospitalized patients with intra-abdominal infection.

METHODS

A total of 149 patients received piperacillin/tazobactam 4 g/500 mg every 8 hours, and 144 patients received imipenem/cilastatin 500 mg/500 mg every 6 hours. Efficacy was evaluated by clinical and bacteriological response. Safety was evaluated by analysis of adverse events and physical and laboratory examinations.

RESULTS

Clinical and bacteriological responses in both evaluable treatment groups were equivalent. The clinical success was 97% (108/111) for piperacillin/tazobactam and 97% (100/103) for imipenem/cilastatin. Bacteriological success was 97% (67/69) for piperacillin/tazobactam and 95% (61/64) for imipenem/cilastatin. The most common pathogens were Escherichia coli, Klebsiella pneumoniae, Enterobacter species and Pseudomonas aeruginosa. The frequencies of treatment-related adverse events were similar (16 with piperacillin/tazobactam and 19 with imipenem/cilastatin).

CONCLUSIONS

These results suggest that the safety and efficacy of piperacillin/tazobactam administered every 8 hours are equivalent to those of imipenem/cilastatin administered every 6 hours for the treatment of intra-abdominal infections.

The role of beta-lactam/beta-lactamase inhibitor combinations in surgical infections

Many surgical infections are characterized by synergistic polymicrobial mixed infection, for which broad-spectrum antimicrobial therapy is usually administered on an empiric basis. Until relatively recently, standard empiric therapeutic regimens have involved the use of two or more antibiotics, such as aminoglycosides and anti-anaerobic agents, to achieve adequate aerobic and anaerobic coverage. There are often substantial drawbacks, however, such as drug-induced toxicity and high costs of treatment. Evidence from a number of clinical studies suggests that single-agent therapy with beta-lactam/beta-lactamase inhibitor combinations is a suitable and cost-effective alternative to multidrug regimens, as well as to monotherapy with cephalosporins or carbapenems in the treatment of intra-abdominal, gynecologic, and diabetic foot infections, and brain abscesses. These agents are also suitable for use in perioperative prophylaxis and may offer benefits over other agents in terms of reduced incidence of surgical wound infections and lower costs.

Comparative in vitro activity of piperacillin, piperacillin–sulbactam and piperacillin-tazobactam against nosocomial pathogens isolated from intensive care patients

We investigated the antimicrobial activity of piperacillin-tazobactam versus piperacillin-sulbactam against common nosocomial pathogens (n = 565) isolated from intensive care patients. For Gram-positive bacteria, antimicrobial susceptibilities to the two piperacillin-beta-lactamase inhibitor combinations were almost identical. For Gram-negative bacteria, piperacillin-tazobactam exhibited greater activity against Escherichia coli and Proteus vulgaris than piperacillin-sulbactam. Both combinations, however, were equally effective against the other Enterobacteriaceae and Pseudomonas aeruginosa isolates. Piperacillin-sulbactam exhibited better antimicrobial activity against Acinetobacter baumannii. Our findings might prove important for the appropriate choice of antibiotic therapy with beta-lactam-beta-lactamase inhibitor combinations.

Clinical role of beta-lactam/beta-lactamase inhibitor combinations

The use of beta-lactamase inhibitors in combination with beta-lactam antibiotics is currently the most successful strategy to combat a specific resistance mechanism. Their broad spectrum of activity originates from the ability of respective inhibitors to inactivate a wide range of beta-lactamases produced by Gram-positive, Gram-negative, anaerobic and even acid-fast pathogens. Clinical experience confirms their effectiveness in the empirical treatment of respiratory, intra-abdominal, and skin and soft tissue infections. There is evidence to suggest that they are efficacious in treating patients with neutropenic fever and nosocomial infections, especially in combination with other agents. beta-Lactam/beta-lactamase inhibitor combinations are particularly useful against mixed infections. Their role in treating various multi-resistant pathogens such as Acinetobacter species and Stenotrophomonas maltophilia are gaining importance. Although, generally, they do not constitute reliable therapy against extended-spectrum beta-lactamase producers, their substitution in place of cephalosporins appears to reduce emergence of the latter pathogens. Similarly, their use may also curtail the emergence of other resistant pathogens such as Clostridium difficile and vancomycin-resistant enterococci. beta-Lactam/beta-lactamase inhibitor combinations are generally well tolerated and their oral forms provide effective outpatient therapy against many commonly encountered infections. In certain scenarios, they could even be more cost-effective than conventional combination therapies. With the accumulation of so much clinical experience, their role in the management of infections is now becoming more clearly defined.

Risk factors for piperacillin/tazobactam-resistant Escherichia coli in ICU patients: a clinical study

OBJECTIVE

To determine risk factors of infections with piperacillin/tazobactam-resistant Escherichia coli in critical care patients.

DESIGN

Prospective, consecutive sample survey study.

SETTING

Surgical intensive care unit (ICU) in a university hospital.

PATIENTS

A consecutive series of 133 patients from whom culture results were positive for E. coli during their ICU stay.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Multivariate logistic regression analysis identified the following significant independent factors associated with the emergence of a piperacillin/tazobactam-resistant Escherichia coli: prior use of amoxicillin (odds ratio, 4.15) and amoxicillin/clavulanate (odds ratio, 3.25).

CONCLUSIONS

Treatment with amoxicillin or amoxicillin/clavulanate is a major risk factor for the detection of piperacillin/tazobactam-resistant E. coli in ICU patients.

The role of beta-lactam antimicrobials as single agents in treatment of intra-abdominal infection

Broad-spectrum beta-lactam antibiotics have several advantages in the treatment of intra-abdominal infections. These agents are effective against gram-negative rods and anaerobes, reach therapeutic levels rapidly after parenteral administration, and, in the absence of penicillin allergy, generally exhibit low toxicity. The second-generation cephalosporins (e.g., cefoxitin, cefotetan) are used widely in surgical prophylaxis, trauma, and treatment of mild-to-moderate community-acquired infections, but limitations in their spectra and microbial resistance restrict their utility in more serious infections. Extended-spectrum penicillin/beta-lactamase-inhibitor combinations are effective in the treatment of intra-abdominal infections and include enterococci in their spectrum. Gram-negative aerobe resistance has developed to ampicillin/sulbactam. Piperacillin/tazobactam, a ureidopenicillin with increased gram-negative coverage and enhanced antipseudomonal activity, has proved to be effective in clinical trial therapy for intra-abdominal infections. The very broad spectrum carbapenems--imipenem/cilastatin and meropenem--are effective for serious infections or resistant organisms and are often used in the intensive care unit or for nosocomial intra-abdominal infection. These classes of beta-lactams comprise a range of antimicrobials that can be targeted effectively as single agents to both prevention and treatment of intra-abdominal infection.

Diagnosis and treatment of intra-abdominal abscesses

Despite recent advances in the diagnosis and management of intra-abdominal abscesses, these infections still cause substantial morbidity and mortality. Low pH, large bacterial inocula, poor perfusion, the presence of hemoglobin, and large amounts of fibrin (which impedes antibiotic penetration) make the abscess a cloistered environment that is penetrated poorly by many antimicrobial therapies. Therefore, management of these infections requires prompt recognition, early localization, and effective drainage, as well as appropriate antimicrobial use. Although various imaging techniques, such as ultrasonography, gallium scans, and indium-labeled white-blood-cell scans, can be used for the diagnosis and localization of intra-abdominal abscesses, computer-assisted tomography is the most useful study. Once the diagnosis is made and the abscess is localized, treatment should begin promptly. Percutaneous or open surgical drainage should be used. Broad-spectrum antibiotics should be given until culture and sensitivity data are obtained. Once these data are obtained, a therapy with appropriate coverage that is likely to work in the abscess environment should be chosen. Percutaneous drainage is inappropriate for abscesses in the posterior subphrenic space or in the porta hepatis, for those among loops of small bowel, for suspected echinococcal cysts, and for abscesses containing necrotic or neoplastic tissues. Finally, surgeons need to be cognizant of risk factors, such as advanced age, obesity, complex abscesses, and high Acute Physiology and Chronic Health Evaluation (APACHE) II or APACHE III scores, which correlate with poor outcomes for these patients.

Intra-abdominal anaerobic infections: bacteriology and therapeutic potential of newer antimicrobial carbapenem, fluoroquinolone, and desfluoroquinolone therapeutic agents

Intra-abdominal infections are biphasic, synergistic processes with early peritonitis and bacteremia due to aerobes and a later abscess component due to anaerobes. Although Bacteroides fragilis is the most commonly recognized pathogen, other anaerobes, including other members of the B. fragilis-group species, are major components of infection. Anaerobic bacteremia is often associated with an intra-abdominal source. New antimicrobial agents with anaerobic activity are in various stages of development for the therapy of intra-abdominal infections. The in vitro activity and the currently available sparse clinical data are reviewed for a new carbapenem (ertapenem), several fluoroquinolones (trovafloxacin, moxifloxacin, and gemifloxacin), and a desfluoroquinolone (BMS-284756).

Potency and antimicrobial spectrum update for piperacillin/tazobactam (2000): emphasis on its activity against resistant organism populations and generally untested species causing community-acquired respiratory tract infections

The in vitro activity of piperacillin/tazobactam and several comparison broad-spectrum compounds was assessed against recent clinical isolates of Gram-positive and -negative bacteria from geographically diverse medical centers in Europe, North and Latin America participating in various surveillance programs in 2000. Several organisms were characterized for phenotypic expression of various resistant determinants such as extended-spectrum beta-lactamase (ESBL) or amp C cephalosporinase hyperproduction, and vancomycin resistance in enterococci (VRE). Piperacillin/tazobactam retained activity (MIC50) against oxacillin-susceptible Staphylococcus spp. (0.12-0.5 microg/ml), Bacillus spp. (0.5 microg/ml), vancomycin-susceptible enterococci (>4 microg/ml), and Corynebacterium spp. (2 microg/ml; not including C. jeikeium) with susceptibility rates of 100.0, 91.7, 85.7 and 81.8%, respectively. Piperacillin/tazobactam inhibited all Streptococcus spp. strains at < or = 16 microg/ml, including penicillin-resistant strains many of which were co-resistant to erythromycin (90%) and other beta-lactams. A specific breakpoint for these streptococci when testing piperacillin/tazobactam appears needed to prevent false-resistant reports using penicillin as a class representative. The carbapenems among beta-lactams were the most active agents against the ESBL-producing species of Escherichia coli and Klebsiella pneumoniae and those strains which hyper-express amp C enzymes including Citrobacter spp. and Enterobacter spp. Piperacillin/tazobactam only exhibited modest activity against the "amp C resistance group" strains (68.8% susceptible or intermediate, MIC < or = 64 microg/ml). Piperacillin/tazobactam (MIC50, 8 microg/ml; 79.5% susceptible) was the most active agent tested against multi-drug resistant isolates of Pseudomonas aeruginosa. Against sampled Haemophilus influenzae (39.2% ampicillin-resistant), piperacillin/tazobactam (MIC(90,) < or = 0.06 microg/ml), ceftriaxone and ceftazidime inhibited 100.0% of the isolates at < or = 0.25 microg/ml. These in vitro surveillance results from the year 2000 on three continents, demonstrated a sustained potent activity of piperacillin/tazobactam against selected problematic nosocomial and community-acquired pathogens. The potential importance of these findings is that this beta-lactamase inhibitor combination can be used an empiric treatment of serious infections in hospital environments where resistance has emerged, as well as covering nearly all isolates of fastidious respiratory tract pathogens acquired in the community setting.

Pharmacokinetic and pharmacodynamic evaluation of two dosing regimens for piperacillin-tazobactam

STUDY OBJECTIVE

To compare the pharmacokinetic and pharmacodynamic profiles of two dosing regimens for piperacillin-tazobactam against commonly encountered pathogens. The regimens compared were piperacillin 4.0 g-tazobactam 0.5 g administered every 8 hours, and piperacillin 3.0 g-tazobactam 0.375 g administered every 6 hours.

DESIGN

Multiple-dose, open-label, randomized, crossover study.

SETTING

Clinical research center at Hartford Hospital.

SUBJECTS

Twelve healthy volunteers.

INTERVENTION

The two dosing regimens for piperacillin-tazobactam were administered intravenously in crossover design. Blood was sampled after the third dose.

MEASUREMENTS AND MAIN RESULTS

Drug concentrations were determined by a validated high-performance liquid chromatography assay. The percentage of time above minimum inhibitory concentration (%T>MIC) for piperacillin was calculated for a range of MIC values. The maximum concentration (Cmax), area under the concentration-time curve (AUC0-tau), and total clearance of piperacillin differed significantly between the two study regimens, as did the Cmax, AUC0-tau, volume of distribution, and total clearance of tazobactam (p<0.05). The piperacillin 4.0 g-tazobactam 0.5 g regimen provided 40-50% T>MIC for MIC values 8-16 microg/ml; a similar value for the piperacillin 3.0 g-tazobactam 0.375 g regimen was 16-32 microg/ml.

CONCLUSION

Although statistically significant differences in the pharmacodynamic profile were noted for the regimens, both provide adequate T>MIC against commonly encountered pathogens considered susceptible to piperacillin-tazobactam. However, for treatment of Pseudomonas aeruginosa infection, combination therapy or higher-dosage regimens (e.g., piperacillin 3.0 g-tazobactam 0.375 g every 4 hours, piperacillin 4.0 g-tazobactam 0.5 g every 6 hours, or continuous-infusion piperacillin 12 g-tazobactam 1.5 g/day) may be a prudent option when full MIC data are unavailable.

Piperacillin 2 g/tazobactam 0.5 g is as effective as imipenem 0.5 g/cilastatin 0.5 g for the treatment of acute uncomplicated pyelonephritis and complicated urinary tract infections

This randomised, double-blind, multicentre trial compared piperacillin/tazobactam (2 g/0.5 g/q8h) and imipenem/cilastatin (0.5 g/0.5 g/q8h) as monotherapy in patients with acute pyelonephritis or complicated urinary tract infections. In total, 237 patients were randomised to receive either piperacillin/tazobactam (n=161) or imipenem/cilastatin (n=166). At the early follow-up (=test-of-cure-visit) 5-9 days after antibiotic therapy, clinical success was noted in 122/147 (83.0%) piperacillin/tazobactam recipients compared with 123/154 (79.9%) imipenem/cilastatin recipients, thus proving that both treatments were equally effective. On a descriptive level, an advantage of piperacillin/tazobactam was demonstrated. Microbiological success at the early follow-up was 78/135 (57.8%) for piperacillin/tazobactam and 70/144 (48.6%) for imipenem/cilastatin. These results were confirmed by equivalent success rates on the last therapy day. Both drugs were generally well tolerated.

The microbiology of postoperative peritonitis

Postoperative peritonitis carries a higher risk of complications and mortality than does community-acquired disease. Little, however, is known about the specific microbiology of this condition. To gain insight into this problem, the microbiological findings of 67 patients with postoperative peritonitis were compared with those of 68 patients with community-acquired peritonitis. In a comparison of postoperative peritonitis with community-acquired disease, the number of isolates of enterococci (23 versus 6) and Enterobacter species (13 versus 4) were increased and the number of isolates of Escherichia coli (21 versus 42) were reduced. Antibiotic therapy before reintervention increased the number of resistant organisms at relaparotomy (33% versus 8%). The in vitro efficacy of the primary antibiotic or combination of drugs did not affect mortality rates (40% versus 38% after effective and ineffective treatment, respectively). Thus, the microbiology of postoperative peritonitis differs significantly from that of community-acquired disease, and specific antibiotic therapy is required, despite the doubtful impact on survival.

Results of a clinical trial of clinafloxacin versus imipenem/cilastatin for intraabdominal infections

OBJECTIVE

Clinafloxacin is a novel quinolone with wide activity against the plethora of microorganisms encountered in intraabdominal infections. This trial was performed to examine its clinical efficacy.

SUMMARY BACKGROUND DATA

Clinafloxacin is representative of a new class of quinolones with considerable antimicrobial activity resulting from their mechanisms of action and pharmacodynamics. There is, however, concern about specific potential toxicities, including photosensitivity.

METHODS

This prospective, randomized, double-blind trial was conducted to compare clinafloxacin with imipenem/cilastatin as adjuncts in the management of complicated intraabdominal infections.

RESULTS

Five hundred twenty-nine patients were included in the intent-to-treat population, with 312 meeting all criteria for the valid population. Patients with a wide range of infections were enrolled; perforated or abscessed appendicitis was the most common (approximately 50%). One hundred twenty-three of the 150 valid patients treated with clinafloxacin (82%) had successful outcomes, as did 130 of the 162 (80%) treated with imipenem. For the intent-to-treat groups, 219 of 259 patients treated with clinafloxacin (85%) had successful outcomes, as did 219 of 270 patients treated with imipenem/cilastatin (81%). Treatment failure occurred in 39 patients who underwent drainage. There were substantially more gram-negative organisms recovered from the patients with treatment failure who were initially treated with imipenem/cilastatin.

CONCLUSIONS

The results of this study clearly demonstrate the safety and efficacy of clinafloxacin in the treatment of a range of intraabdominal infections, and in patients with a broad range of physiologic disturbances.

Cost efficacy of tazobactam/piperacillin versus imipenem/cilastatin in the treatment of intra-abdominal infection

OBJECTIVE

To compare the cost, efficacy and cost efficacy of tazobactam/piperacillin and imipenem/cilastatin in the treatment of intra-abdominal infection.

DESIGN

The analysis was retrospective and based on a decision tree. Effectiveness data were obtained from 19 published clinical trials. Direct costs were quantified per patient from the time the decision was made to administer the antibacterial to the end of the first course of treatment or the end of a subsequent course of treatment, if required. The primary end-point was the cost per successfully treated patient. The cost per life saved was also analysed. Various follow-up times were taken into account.

PERSPECTIVE

German National Health Insurance funds.

STUDY POPULATION

1744 patients with intra-abdominal infection.

INTERVENTIONS

Tazobactam/piperacillin (total daily dosage of 13.5 g/day) and imipenem/cilastatin (total daily dosage of 1.5 to 4 g/day). The mean duration of treatment varied from 5.5 to 8.2 days for tazobactam/piperacillin and 5 to 9.4 days for imipenem/cilastatin.

MAIN OUTCOME MEASURE AND RESULTS

Compared with imipenem/cilastatin, treatment with tazobactam/piperacillin was more effective and the overall treatment costs were lower. In the base-case analysis, the cost-efficacy ratio (cost per successfully treated patient) was 7881 German deutschmarks (DM) for tazobactam/piperacillin and DM11,390 for imipenem/cilastatin. The incremental cost-efficacy ratio (per life saved) varied between -DM72,567 and -DM350,738 for tazobactam/piperacillin. Sensitivity analyses revealed that the results were robust against various assumptions on cost parameters, clinical outcomes and length of treatment. All costs reflect 1998 values; $US1 = DM1.85.

CONCLUSIONS

This study suggests that compared with imipenem/cilastatin, tazobactam/piperacillin is more cost efficacious in the treatment of intra-abdominal infections and that it offers a cost advantage through fewer relapses and lower daily therapeutic costs.

Piperacillin/tazobactam: a pharmacoeconomic review of its use in moderate to severe bacterial infections

Piperacillin/tazobactam is a beta-lactam/beta-lactamase inhibitor combination with a broad spectrum of antibacterial activity against most Gram-positive and Gram-negative aerobic bacteria and anaerobic bacteria. Piperacillin/tazobactam is effective and well-tolerated in patients with lower respiratory tract infections (LRTI), intra-abdominal infections, skin and soft tissue infections, and febrile neutropenia. In comparative clinical trials against various other antibacterial regimens, piperacillin/tazobactam has shown higher clinical success rates, particularly in the treatment of patients with intra-abdominal infections and febrile neutropenia. Cost analyses of piperacillin/tazobactam have been variable, in part, because of differences in specific costs included. Three US cost analyses found that piperacillin/tazobactam had lower total medical costs than clindamycin plus gentamicin or imipenem/cilastatin in intra-abdominal infections, and ticarcillin/ clavulanic acid in community-acquired pneumonia. Piperacillin/tazobactam plus amikacin had lower total costs than ceftazidime plus amikacin in another cost analysis of patients with febrile neutropenic episodes modelled in nine European countries. However, piperacillin/tazobactam plus tobramycin was more costly than ceftazidime plus tobramycin in hospital-acquired pneumonia in a US cost analysis. In cost-effectiveness analyses, all studies of intra-abdominal infections, pneumonia and febrile neutropenic episodes consistently reported lower costs per unit of effectiveness versus comparators. Piperacillin/tazobactam was dominant (greater efficacy and lower costs) versus imipenem/cilastatin in intra-abdominal infections and ceftriaxone, ciprofloxacin or meropenem in pneumonia. Piperacillin/tazobactam plus amikacin was dominant over ceftazidime plus amikacin in the treatment of febrile neutropenic episodes. In a cost-effectiveness analysis of skin and soft tissue infection, piperacillin/tazobactam had lower costs per successfully treated patient than ceftriaxone or cefotaxime, but a slightly higher cost-effectiveness ratio than amoxicillin/clavulanic acid. All cost-effectiveness analyses were based on decision-analytical models.

CONCLUSIONS

Piperacillin/tazobactam is likely to reduce overall treatment costs of moderate to severe bacterial infections by increasing initial treatment success, thereby reducing the length of hospital stay and the use of additional antibacterials. Piperacillin/tazobactam has shown clinical and economic advantages over standard antibacterial regimens in the treatment of intra-abdominal infections, LRTIs, febrile episodes in patients with neutropenia, and skin and soft tissue infections, although more complete published data are needed to confirm these results. Present data regarding clinical efficacy, bacterial resistance and costs would support the use of piperacillin/tazobactam as an empirical first-line option in moderate to severe bacterial infections.

Comparison of intravenous/oral ciprofloxacin plus metronidazole versus piperacillin/tazobactam in the treatment of complicated intraabdominal infections

OBJECTIVE

To compare the safety and efficacy of intravenous (IV) ciprofloxacin plus IV metronidazole (CIP+MET) with that of IV piperacillin/tazobactam (PIP/TAZO) in adults with complicated intraabdominal infections, and to compare the efficacy of sequential IV-to-oral CIP+MET therapy with that of the IV CIP-only regimen.

SUMMARY BACKGROUND DATA

Treatment of intraabdominal infections remains a challenge, mainly because of their polymicrobial etiology and attendant death and complications. Antimicrobial regimens using sequential IV-to-oral therapy may reduce the length of hospital stay.

METHODS

In this multicenter, randomized, double-blind trial involving 459 patients, clinically improved IV-treated patients were switched to oral therapy after 48 hours. Overall clinical response was the primary efficacy measurement.

RESULTS

A total of 282 patients (151 CIP+MET, 131 PIP/TAZO) were valid for efficacy. Of these patients, 64% CIP+MET and 57% PIP/TAZO patients were considered candidates for oral therapy. Patients had a mean APACHE II score of 9.6. The most common diagnoses were appendicitis (33%), other intraabdominal infection (29%), and abscess (25%). Overall clinical resolution rates were statistically superior for CIP+MET (74%) compared with PIP/TAZO (63%). Corresponding rates in the subgroup suitable for oral therapy were 85% for CIP+MET and 70% for PIP/TAZO. Postsurgical wound infection rates were significantly lower in CIP+MET (11%) versus PIP/TAZO patients (19%). Mean length of stay was 14 days for CIP+MET and 17 days for PIP/TAZO patients.

CONCLUSION

CIP+MET, initially administered IV and followed by CIP+MET oral therapy, was clinically more effective than IV PIP/TAZO for the treatment of patients with complicated intraabdominal infections.