Antibiotic monotherapy with meropenem in the surgical management of intra-abdominal infections

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.

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.

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.

Optimal Treatment for Complicated Intra-abdominal Infections in the Era of Antibiotic Resistance: A Systematic Review and Meta-Analysis of the Efficacy and Safety of Combined Therapy With Metronidazole

Background.  Carbapenem-resistant Enterobacteriaceae 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. A combination of metronidazole with an antimicrobial agent active against aerobes is an alternative effective treatment for patients with complicated intra-abdominal infections (cIAIs). This study aimed to compare efficacy and safety of metronidazole combination therapies and carbapenem and to provide clinical evidence regarding the optimal treatment of cIAI. Methods.  A systematic review and a meta-analysis of randomized clinical trials in the treatment of cIAI were conducted. The systematic review with PubMed, Embase, and the Cochrane Database of Systematic Reviews followed the Cochrane Handbook's recommended methodology, and the meta-analysis used a Mantel-Haenszel random-effects model with RevMan, version 5.3. Primary endpoints were clinical success and bacteriological eradication, and secondary endpoints were all-cause mortality and drug-related adverse events. Results.  Eight studies comparing metronidazole combination therapies and carbapenem were included in the meta-analysis. No difference was found between combined therapy with metronidazole and carbapenem regarding clinical success (odds ratio [OR] = 1.31; 95% confidence interval [CI], .75-2.31), bacteriological eradication (OR = 1.27; 95% CI, .84-1.91), all-cause mortality (OR = 0.61; 95% CI, .37-1.00), or drug-related adverse events (OR = 0.58; 95% CI, .18-1.88). Sensitivity analyses found similar results. Conclusions.  Combined therapy with metronidazole is as effective and safe as carbapenem in treatment of cIAI. Therefore, combined therapy with metronidazole offers an effective alternative to carbapenem with low risk of drug resistance.

The risk of seizures among the carbapenems: a meta-analysis

OBJECTIVES

A consensus exists among clinicians that imipenem/cilastatin is the most epileptogenic carbapenem, despite inconsistencies in the literature.

METHODS

We conducted a meta-analysis of all randomized controlled trials comparing carbapenems with each other or with non-carbapenem antibiotics to assess the risk of seizures for imipenem, meropenem, ertapenem and doripenem.

RESULTS

In the risk difference (RD) analysis, there were increased patients with seizure (2 per 1000 persons, 95% CI 0.001, 0.004) among recipients of carbapenems versus non-carbapenem antibiotics. This difference was largely attributed to imipenem as its use was associated with an additional 4 patients per 1000 with seizure (95% CI 0.002, 0.007) compared with non-carbapenem antibiotics, whereas none of the other carbapenems was associated with increased seizure. Similarly, in the pooled OR analysis, carbapenems were associated with a significant increase in the risk of seizures relative to non-carbapenem comparator antibiotics (OR 1.87, 95% CI 1.35, 2.59). The ORs for risk of seizures from imipenem, meropenem, ertapenem and doripenem compared with other antibiotics were 3.50 (95% CI 2.23, 5.49), 1.04 (95% CI 0.61, 1.77), 1.32 (95% CI 0.22, 7.74) and 0.44 (95% CI 0.13, 1.53), respectively. In studies directly comparing imipenem and meropenem, there was no difference in epileptogenicity in either RD or pooled OR analyses.

CONCLUSIONS

The absolute risk of seizures with carbapenems was low, albeit higher than with non-carbapenem antibiotics. Although imipenem was more epileptogenic than non-carbapenem antibiotics, there was no statistically significant difference in the imipenem versus meropenem head-to-head comparison.

Imipenem and meropenem: Comparison of in vitro activity, pharmacokinetics, clinical trials and adverse effects

OBJECTIVE

To compare and contrast imipenem and meropenem in terms of in vitro activity, pharmacokinetics, clinical efficacy and adverse effects.

DATA SELECTION

MEDLINE search from 1975 to 1997 and follow-up of references.

DATA EXTRACTION

Clinical trials comparing imipenem with meropenem, or either imipenem or meropenem with standard therapy in the treatment of serious infections were selected.

DATA SYNTHESIS

Imipenem, the first carbapenem, was first marketed in 1987; meropenem was introduced to the market in 1996. In general, imipenem is more active against Gram-positive cocci while meropenem is more active against Gram-negative bacilli. The agents display similar pharmacokinetics. Clinical studies in patients with serious infections (intra-abdominal infection, respiratory infection, septicemia, febrile neutropenia) report similar bacteriological and clinical cure rates with imipenem and meropenem. Meropenem is approved for the treatment of bacterial meningitis, whereas imipenem is not. Adverse effects are similar.

CONCLUSIONS

Current literature supports the use of imipenem at a dose of 500 mg every 6 h and meropenem at 1 g every 8 h for the treatment of severe infections. For the treatment of serious infections, imipenem (500 mg every 6 h or 2 g/day [$98/day]) is more economical than meropenem (1 g every 8 h or 3 g/day [$142/day]) based on acquisition cost.

Epidemiology, management, and prognosis of secondary non-postoperative peritonitis: a French prospective observational multicenter study

BACKGROUND

Despite improvements in treatment, secondary peritonitis still is associated with high morbidity and mortality rates. Better knowledge of real-life clinical practice might improve management.

METHODS

Prospective, observational study (January-June 2005) of 841 patients with non-postoperative secondary peritonitis.

RESULTS

Peritonitis originated in the colon (32% of patients), appendix (31%), stomach/duodenum (18%), small bowel (13%), or biliary tract (6%). Most patients (78%) presented with generalized peritonitis and 26% with severe peritonitis (Simplified Acute Physiology Score [SAPS] II score>38). Among the 841 patients, 27.3% underwent laparoscopy alone; 11% underwent repeat surgery, percutaneous drainage, or both. A SAPS II score>38 and the presence of Enterococcus spp. were predictive of abdominal and non-surgical infections (odds ratio [OR]=1.84; p=0.013 and OR=2.93; p<0.0001, respectively). A SAPS II score>38 also was predictive of death (OR=10.5; p<0.0001). The overall mortality rate was high (15%). Patients receiving inappropriate initial antimicrobial therapy had significantly higher morbidity and mortality rates than patients receiving appropriate therapy (44 vs. 30%; p=0.004 and 23% vs. 14%; p=0.015, respectively). The SAPS II score and rates of severe peritonitis, morbidity, and mortality were significantly lower in patients with appendiceal peritonitis.

CONCLUSIONS

Patients with non-postoperative peritonitis should be considered high risk and should receive appropriate initial therapy. The presence of Enterococcus spp. in peritoneal cultures significantly increased morbidity but not the mortality rate. Appendiceal peritonitis that was less severe and had a better prognosis than peritonitis originating in other sites should be considered a special case in future studies.

Update on the efficacy and tolerability of meropenem in the treatment of serious bacterial infections

Meropenem is a carbapenem antibiotic approved by the US Food and Drug Administration for the treatment of complicated skin and skin-structure infections, complicated intra-abdominal infections, and pediatric bacterial meningitis (in patients >or=3 months of age). In clinical trials, it also has shown efficacy as initial empirical therapy for the treatment of nosocomial pneumonia. Unlike other beta-lactam antibiotics, including third-generation cephalosporins, carbapenems have shown activity against extended-spectrum beta-lactamase-producing and AmpC chromosomal beta-lactamase-producing bacteria. Compared with imipenem, meropenem is more active against gram-negative pathogens and somewhat less active against gram-positive pathogens, and it does not require coadministration of a renal dehydropeptidase inhibitor. In most comparative trials, clinical and bacteriological response rates with imipenem and meropenem were similar. Compared with clindamycin/tobramycin, meropenem is associated with a reduced length of hospital stay and a shorter duration of therapy among patients with complicated intra-abdominal infections. Meropenem is well tolerated by children and adults and has an acceptable safety profile. Alternative meropenem dosing strategies for the optimization of outcomes are under investigation.

Meropenem: a review of its use in the treatment of serious bacterial infections

Meropenem (Merrem, Meronem) is a broad-spectrum antibacterial agent of the carbapenem family, indicated as empirical therapy prior to the identification of causative organisms, or for disease caused by single or multiple susceptible bacteria in both adults and children with a broad range of serious infections. Meropenem is approved for use in complicated intra-abdominal infection (cIAI), complicated skin and skin structure infection (cSSSI) and bacterial meningitis (in paediatric patients aged > or = 3 months) in the US, and in most other countries for nosocomial pneumonia, cIAI, septicaemia, febrile neutropenia, cSSSI, bacterial meningitis, complicated urinary tract infection (UTI), obstetric and gynaecological infections, in cystic fibrosis patients with pulmonary exacerbations, and for the treatment of severe community-acquired pneumonia (CAP). Meropenem has a broad spectrum of in vitro activity against Gram-positive and Gram-negative pathogens, including extended-spectrum beta-lactamase (ESBL)- and AmpC-producing Enterobacteriaceae. It has similar efficacy to comparator antibacterial agents, including: imipenem/cilastatin in cIAI, cSSSI, febrile neutropenia, complicated UTI, obstetric or gynaecological infections and severe CAP; clindamycin plus tobramycin or gentamicin in cIAI or obstetric/gynaecological infections; cefotaxime plus metronidazole in cIAI; cefepime and ceftazidime plus amikacin in septicaemia or febrile neutropenia; and ceftazidime, clarithromycin plus ceftriaxone or amikacin in severe CAP. Meropenem has also shown similar efficacy to cefotaxime in paediatric and adult patients with bacterial meningitis, and to ceftazidime when both agents were administered with or without tobramycin in patients with cystic fibrosis experiencing acute pulmonary exacerbations. Meropenem showed greater efficacy than ceftazidime or piperacillin/tazobactam in febrile neutropenia, and greater efficacy than ceftazidime plus amikacin or tobramycin in patients with nosocomial pneumonia. Meropenem is well tolerated and has the advantage of being suitable for administration as an intravenous bolus or infusion. Its low propensity for inducing seizures means that it is suitable for treating bacterial meningitis and is the only carbapenem approved in this indication. Thus, meropenem continues to be an important option for the empirical treatment of serious bacterial infections in hospitalized patients.

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.

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.

Antibiotic prophylaxis and treatment of surgical abdominal sepsis

The incidence of surgical abdominal sepsis is related to the operation, patient and skill of the surgeon, ranging from <2-3% for laparoscopic cholecystectomy to >35-40% in overt peritonitis. Aged, obese, diabetic, neoplastic, acute patients have the highest incidence of sepsis. Antibiotic prophylaxis significantly reduces the incidence of postoperative infections for Class II and II operations. The proper timing (30-60 min before incision), choice of antibiotic (related to possible pathogens) and correct duration are essential. Ultra-short prophylaxis (only one administration) may be effective in most class II procedures and a cephalosporin can be used. Class II operations (colorectal) may require a booster dose soon after surgery or during surgery exceeding 3 h. The most effective regimen may include: ampicillin, clindamycin, I- II- III- or IV-generation cephalosporins, amoxycillin, aminoglycosides, metronidazole have been used alone and in combination. Combination prophylaxis should be active against aerobic and anaerobic bacteria. Treatment of surgical abdominal sepsis may be primary, seconday or tertiary. Surgery should remove the pathologic lesion, and antibiotics reduce the general effects of sepsis and infectious complications. This article presents information on the general rules for correct prophylaxis and treatment.

Convalescent phase outpatient parenteral antiinfective therapy for children with complicated appendicitis

BACKGROUND

Children with a perforated or gangrenous appendix become clinically stable after medical and/or surgical therapy but often remain in the hospital solely to complete parenteral antibiotic therapy. This prospective study investigates the outcomes when children who meet specified criteria are discharged to complete parenteral antibiotic therapy at home.

METHODS

Children age 1 to 17 years with appendicitis complicated by generalized peritonitis or intraabdominal abscess were eligible to participate. Subjects whose fever was decreasing, who were able to tolerate oral liquids and for whom further parenteral antibiotic therapy was deemed necessary were discharged from the hospital to receive outpatient parenteral antiinfective therapy (OPAT) with meropenem. Therapy was administered by a family member and supervised by home care nurses. Study personnel visited the home daily to collect data on adverse events, compliance and resource utilization. Pa tients served as their own controls in models of reduced hospitalization and net cost savings.

RESULTS

Discharged on average on the fourth postoperative day, 87 children received 4.5 +/- 2.1 days of OPAT. Six (7%) children were subsequently readmitted for complications including bowel obstruction (4 children), intraabdominal abscess (1 child) and pleural effusion (1 child). Another child developed a viral syndrome during OPAT. All other patients recovered uneventfully. Six (7%) children discontinued meropenem prematurely because of rash (4 patients) or diarrhea (2 patients). According to models in which each day of OPAT replaced a day of inpatient care, discharge to OPAT reduced hospitalization by 42 +/- 15% and saved a median of $2908 (10th to 90th percentile range, $1,077 to $4,707) per patient.

CONCLUSION

Convalescent phase OPAT is a cost-effective alternative to continued hospitalization for children with complicated appendicitis who are clinically stable yet require further parenteral antibiotic therapy.

Monotherapy versus combination therapy for bacterial infections

The authors discuss the latest findings regarding the use of one or more antimicrobial drugs for a variety of infections. They offer suggestions for treatment based on a host of considerations, including the synergy and antagonism of specific drugs, type of infection, potential toxicities, and cost.

Meropenem: an updated review of its use in the management of intra-abdominal infections

Meropenem is a carbapenem antibacterial agent with a broad spectrum of activity which encompasses gram-negative, gram-positive and anaerobic bacteria. Like other carbapenems, meropenem is stable against chromosomal and extended-spectrum beta-lactamases. In patients with moderate to severe intra-abdominal infections, empirical monotherapy with meropenem achieved clinical response rates ranging from 91 to 100% in 7 randomised comparative trials. Efficacy rates were similar to those of imipenem/cilastatin (94 to 97%), clindamycin plus tobramycin (93%) and, overall, to cefotaxime plus metronidazole (75 to 100%), although there were differences between trials versus this combination regimen. According to limited data, meropenem also achieved clinical response rates of over 80% in patients with severe intra-abdominal infections. Meropenem is well tolerated, the most common adverse events being diarrhoea, rash, nausea/vomiting and inflammation at the injection site which are reported in <2.5% of patients each. Meropenem also has an improved CNS tolerability profile compared with imipenem/cilastatin.

CONCLUSIONS

Extensive comparative clinical data demonstrate that meropenem can be used effectively as empirical monotherapy in moderate to severe intra-abdominal infections. It also shows potential in the most severe forms of infection, although experience in this infection type remains limited. Compared with standard combination regimens, meropenem offers the benefits of ease of administration without the need for monitoring. It also offers improved CNS tolerability compared with imipenem/cilastatin with the option of a higher maximum dosage, which may be a particular advantage in patients with severe intra-abdominal infections.

Meropenem versus imipenem/cilastatin as empirical monotherapy for serious bacterial infections in the intensive care unit

OBJECTIVE

To compare the efficacy and tolerability of meropenem and imipenem/cilastatin as empirical monotherapy in intensive care unit (ICU) patients with serious bacterial infections.

METHODS

A multicenter, open-label, randomized, parallel-group trial was conducted in Belgium, evaluating empirical monotherapy with meropenem or imipenem/cilastatin (both 1 g/8 h intravenously) in ICU patients with one or more of the following infections caused by sensitive pathogens: lower respiratory tract infection (LRTI) in ventilated patients, intra-abdominal infection or sepsis.

RESULTS

The overall satisfactory clinical response rate at the end of randomized treatment was 77.0% (67/87) with meropenem and 68.1% (62/91) with imipenem/cilastatin (difference 8.9%; 95% confidence interval -4.2% to 21.9%; P = 0.185). The two drugs produced similar satisfactory clinical response rates against LRTIs: 68.3% (41/60) with meropenem versus 68.6% (35/51) with imipenem/cilastatin. Meropenem appeared to be slightly more effective against intra-abdominal infections: 95.5% (21/22) versus 76.7% (23/30), respectively. All five meropenem recipients with sepsis had a satisfactory clinical response, compared to 40.0% (4/10) of those who received imipenem/cilastatin. The overall satisfactory bacteriologic response rate was 67.1% (49/73) with meropenem and 60.3% (44/73) with imipenem/cilastatin (difference 6.9%; 95% confidence interval -8.7% to 22.4%; P = 0.389). The predominant pathogens were Escherichia coli, Enterobacter spp. and Pseudomonas aeruginosa. No incidences of drug-related nausea and vomiting were reported, but one probable drug-related seizure occurred in the imipenem/cilastatin group.

CONCLUSIONS

Meropenem is at least as efficacious (clinically and bacteriologically) as imipenem/cilastatin for the empirical monotherapy of serious bacterial infections in ICU patients, and it can therefore be considered a useful option in this setting. Moreover, meropenem is well tolerated and offers several potential advantages, including greater in vitro activity against Gram-negative pathogens and the option of bolus administration.

Meropenem: clinical response in relation to in vitro susceptibility

OBJECTIVE

To collate the clinical response and pathogen eradication rates for meropenem monotherapy with in vitro susceptibility of the causative pathogens.

METHODS

Data were compiled from 17 randomized clinical studies that compared meropenem monotherapy with standard treatment options, often combinations. A total of 4906 pathogens from lower respiratory tract, intra-abdominal, obstetric/gynecological, skin/soft tissue, meningitis, or pediatric infections were assessed. Of these, 3713 pathogens (1963 meropenem, 1750 comparators) were evaluable.

RESULTS

The overall rates of satisfactory clinical response (cure or improvement) and pathogen eradication (eradication or presumed eradication) at the end of therapy were similar with meropenem (93% for both responses) and the comparators (92%), as were the rates in each infection type. For each pathogen, the clinical response and eradication rates with meropenem were similar across the minimum inhibitory concentration (MIC) range of < or = 0.25 to 4 mg/L. Overall, a satisfactory clinical response occurred in 93% (1580 of 1708) of infections caused by nonfastidious pathogens with MICs < or = 4 mg/L and in 84% (16 of 19) of those with an MIC of 8 mg/L. Pathogen eradication rates were similar (93 and 79%, respectively). A similar profile was observed for fastidious pathogens. The high rates of satisfactory clinical response and pathogen eradication produced by meropenem in each type of infection were generally independent of the causative pathogen, whether Gram-positive or -negative aerobe or anaerobe or when occurring as mono- or polymicrobial infections.

CONCLUSIONS

The attractive in vitro profile of meropenem translates into good clinical efficacy. The National Committee for Clinical Laboratory Standards has now defined meropenem MIC breakpoints for nonfastidious aerobes or anaerobes as < or = 4 (susceptible), 8 (intermediate) and > or = 16 mg/L (resistant), respectively. The susceptibility breakpoint for Streptococcus spp. (excluding Streptococcus pneumoniae) is < or = 0.5 mg/L and, since meropenem is indicated for the treatment of meningitis, the susceptibility breakpoint for S. pneumoniae and Haemophilus influenzae is < or = 0.25 and < or = 0.5 mg/L, respectively. Meropenem monotherapy is therefore a valid option for the initial empirical treatment of a range of serious infections caused by single or multiple bacterial pathogens.

Carbapenems and monobactams: imipenem, meropenem, and aztreonam

Imipenem and meropenem, members of the carbapenem class of beta-lactam antibiotics, are among the most broadly active antibiotics available for systemic use in humans. They are active against streptococci, methicillin-sensitive staphylococci, Neisseria, Haemophilus, anaerobes, and the common aerobic gram-negative nosocomial pathogens including Pseudomonas. Resistance to imipenem and meropenem may emerge during treatment of P. aeruginosa infections, as has occurred with other beta-lactam agents; Stenotrophomonas maltophilia is typically resistant to both imipenem and meropenem. Like the penicillins, the carbapenems have inhibitory activity against enterococci. In general, the in vitro activity of imipenem against aerobic gram-positive cocci is somewhat greater than that of meropenem, whereas the in vitro activity of meropenem against aerobic gram-negative bacilli is somewhat greater than that of imipenem. Daily dosages may range from 0.5 to 1 g every 6 to 8 hours in patients with normal renal function; the daily dose of meropenem, however, can be safely increased to 6 g. Infusion-related nausea and vomiting, as well as seizures, which have been the main toxic effects of imipenem, occur no more frequently during treatment with meropenem than during treatment with other beta-lactam antibiotics. The carbapenems should be considered for treatment of mixed bacterial infections and aerobic gram-negative bacteria that are not susceptible to other beta-lactam agents. Indiscriminate use of these drugs will promote resistance to them. Aztreonam, the first marketed monobactam, has activity against most aerobic gram-negative bacilli including P. aeruginosa. The drug is not nephrotoxic, is weakly immunogenic, and has not been associated with disorders of coagulation. Aztreonam may be administered intramuscularly or intravenously; the primary route of elimination is urinary excretion. In patients with normal renal function, the recommended dosing interval is every 8 hours. Patients with renal impairment require dosage adjustment. Aztreonam is used primarily as an alternative to aminoglycosides and for the treatment of aerobic gram-negative infections. It is often used in combination therapy for mixed aerobic and anaerobic infections. Approved indications for its use include infections of the urinary tract or lower respiratory tract, intra-abdominal and gynecologic infections, septicemia, and cutaneous infections caused by susceptible organisms. Concurrent initial therapy with other antimicrobial agents is recommended before the causative organism has been determined in patients who are seriously ill or at risk for gram-positive or anaerobic infection.

Monobactams and carbapenems for treatment of intraabdominal infections

During the last decade improved clinical and microbiological methods have resulted in the realization that most intraabdominal infections involve both aerobic and anaerobic bacteria. Papers on the use of different antimicrobial agents directed against the polymicrobial flora of the infected site have been published. In this paper the use of monobactams and carbapenems for treatment of intraabdominal infections is reviewed. The review is based on data published since 1990. Three hundred forty-four patients participated in three trials where aztreonam combined with clindamycin was compared with other antimicrobial agents for treatment of intraabdominal infections. Eighty-six percent of the patients receiving aztreonam plus clindamycin were cured/improved, while 83% of the patients receiving the comparative drugs had favorable outcomes. Eleven trials compared imipenem/cilastatin versus other antimicrobial combinations for therapy of intraabdominal infections. One thousand three hundred seventy-five patients were evaluated in the trials. Eighty percent of patients treated with imipenem/cilastatin had favorable outcomes, while 81% of the patients receiving the comparative drugs were cured/improved. Nine studies including 1,205 patients for evaluation of meropenem versus other antimicrobial agents in the treatment of intraabdominal infections have been published. Cure/improvement was seen in 96% of the patients treated with meropenem and in 91% receiving the comparative drugs. One trial has been published comparing biapenem with imipenem/cilastatin for treatment of intraabdominal infections. Eighty-three patients participated, 65% of the patients in the biapenem group were cured/improved and 68% in the imipenem/cilastatin group.

Carbapenems in clinical practice: a guide to their use in serious infection

Meropenem and imipenem/cilastatin, currently the only available carbapenem agents in Europe and the United States, are characterised by a broad spectrum of antimicrobial activity and stability to beta-lactamase-mediated resistance mechanisms. A guide to the use of carbapenems in clinical practice is presented; the role of carbapenems in the treatment of several types of serious bacterial infection and an up-to-date account of their clinical efficacy and safety profiles are discussed. The good clinical efficacy and favourable safety profiles of the carbapenems make them valuable as initial empirical therapy in the treatment of ventilator-associated pneumonia, sepsis of unknown origin, post-operative peritonitis, paediatric meningitis, and febrile neutropenia. However, to maintain superior efficacy, the carbapenems should be used appropriately for definitive therapy.

Meropenem (1.5 g/day) is as effective as imipenem/cilastatin (2 g/day) for the treatment of moderately severe intra-abdominal infections

This multicentre, open-label, randomised trial compared meropenem (0.5 g/8 h) and imipenem/cilastatin (at the commonly used dosage of 0.5 g/6 h) in monotherapy in patients with moderately severe intra-abdominal infections (IAIs). In total, 161 patients were randomised (82 meropenem, 79 imipenem/cilastatin). The mean APACHE II scores in the two groups were 5.8 and 6.4, respectively. At the end of therapy, 65/71 (91.6%) evaluable meropenem recipients were clinically cured or improved, compared to 60/64 (93.8%) imipenem/cilastatin recipients. This difference and that in an intention-to-treat analysis (82.1 vs 86.1%, respectively), were not statistically significant. Both drugs were generally well tolerated. Thus, meropenem 0.5 g/8 h is as clinically effective and well tolerated as imipenem/cilastatin 0.5 g/6 h in moderately severe IAIs.

Meropenem in elderly and renally impaired patients

The safety profile of meropenem in the elderly (aged > 65 years, n=843) and/or renally impaired (creatinine clearance < 51 ml/min, n=436) was assessed by evaluating data from 26 phase III studies which compared the use of meropenem (0.5 or 1.0 g, i.v. every 8 h) with other antimicrobial agents in patients with bacterial infections. The overall pattern and frequency of adverse events following meropenem therapy in the elderly and/or renally impaired were similar to those in younger and/or non-renally impaired cohorts and to imipenem/cilastatin and injectable third generation cephalosporins. Both dosages of meropenem (0.5 and 1.0 g, i.v. every 8 h) were generally well tolerated. There was no clinically significant mean change in indicators of renal flux between baseline and the end of treatment in any patient sub-group. Importantly, meropenem-related seizures were rare (0.1%), even in patients with renal impairment. In summary, meropenem has an excellent safety profile and is therefore suitable for use in elderly and/or renally impaired patients.

Meropenem versus cefuroxime plus gentamicin for treatment of serious infections in elderly patients

In this multicenter study, the efficacy of and tolerability for meropenem were compared with those for the combination of cefuroxime-gentamicin (+/- metronidazole) for the treatment of serious bacterial infections in patients > or = 65 years of age. A total of 79 patients were randomized; thirty-nine received meropenem (1 g/8 h), and 40 received cefuroxime (1.5 g/8 h) plus gentamicin (4 mg/kg of body weight daily) for 5 to 10 days. Metronidazole (500 mg/6 h) could be added to the cefuroxime-gentamicin regimen for the treatment of intra-abdominal infections (n = 10). Seventy patients were evaluable for clinical efficacy; the primary diagnoses were as follows: pneumonia in 41 patients (20 treated with meropenem, 21 treated with cefuroxime-gentamicin), intra-abdominal infection in 10 patients (7 meropenem, 3 cefuroxime-gentamicin-metronidazole), urinary tract infection (UTI) in 11 patients (6 meropenem, 5 cefuroxime-gentamicin), sepsis syndrome in 7 patients (4 meropenem, 3 cefuroxime-gentamicin), and "other" in 1 patient (cefuroxime-gentamicin). The pathogens isolated from 18 patients with bacteremia were as follows: Staphylococcus spp. (n = 2), Streptococcus spp. (n = 2), members of the family Enterobacteriaceae (n = 11), and Bacteroides spp. (n = 3). A satisfactory clinical response at the end of therapy was achieved in 26 of 37 (70%) and 24 of 33 (73%) evaluable patients treated with meropenem and combination therapy, respectively. Clinical success was achieved in 23 of 31 (74%) and 21 of 28 (75%) evaluable patients with infections other than UTIs, respectively. A satisfactory microbiological response occurred in 15 of 22 (68%) patients in the meropenem group compared with 12 of 19 (63%) treated with combination therapy. Renal failure occurred during therapy in 2 of 39 (5%) meropenem recipients compared with 5 of 40 (13%) of those treated with combination therapy. The findings in this small study indicate that meropenem is as efficacious for and as well tolerated by elderly patients as the combination of cefuroxime-gentamicin (+/- metronidazole).

Meta-analysis of the clinical outcome of carbapenem monotherapy in the adjunctive treatment of intra-abdominal infections

BACKGROUND

The carbapenems, a class of beta-lactam antimicrobials with efficacy against both aerobic and anaerobic organisms, have demonstrated potential as monotherapeutic regimens in the treatment of serious intra-abdominal infections. Clinical trials have been conducted in the past decade to compare carbapenem monotherapy versus combinations of antibiotic therapy. We report here a meta-analysis of 10 such trials.

DATA SOURCES

An 11-year Medline search (from 1985 through 1996) of the English-language literature identified clinical trials that compared the outcomes of carbapenem monotherapy, either imipenem/cilastatin or meropenem, versus another antibiotic regimen in intra-abdominal infections in human subjects. Ten randomized, prospective trials were found, with a total of 1,227 clinically evaluable patients. A meta-analysis of these clinical trials was performed to determine the difference in clinical outcomes between carbapenem monotherapy versus other antibiotic regimens. We found a difference in response rates of -1.6% (95% confidence interval [CI] -5.7% to 2.5%) and a response ratio of 0.99 (95% CI, 0.90 to 1.09), indicating no statistical significant difference.

CONCLUSIONS

A meta-analysis of 10 clinical trials from 1985 through 1996 has revealed no statistical significant difference in clinical response between carbapenem monotherapy and combinations of antibiotic therapy in intra-abdominal infections. We noted, however, that the earlier studies reported more favorable response ratios for carbapenems than later publications. This may have been due to the selection of less effective comparators in earlier studies. We conclude that carbapenem monotherapy is as effective as combinations of antimicrobials for the treatment of intra-abdominal infections.

A comparison of the pharmacokinetics of meropenem after intravenous administration by injection over 2, 3 and 5 minutes

The pharmacokinetics of meropenem were determined in 9 healthy volunteers after the administration of 1 g dose by injection over 2, 3 or 5 min. Peak plasma concentrations were not significantly different across the three rates of administration and, due to the finite time required for complete mixing of the blood in the central compartment, did not always occur at the end of the injection. Overall exposure to meropenem was unchanged by the more rapid rates of administration. Plasma clearance, terminal half-life and volume of distribution were virtually unchanged. Within 10 min after the start of the injection, the plasma concentrations from all three injections were very similar indicating that dosing over 2, 3 or 5 min would result in similar antimicrobial cover and, therefore, comparable efficacy. Comparison of the data derived from the three injections indicated that rapid administration of meropenem did not appreciably alter its disposition pharmacokinetics. Tolerability of meropenem was unchanged with the more rapid administration rate.

Meropenem monotherapy versus cefotaxime plus metronidazole combination treatment for serious intra-abdominal infections

In an open, randomised, multicentre trial, the efficacy and tolerability of empirical meropenem monotherapy (1 g intravenously every 8 hours) and cefotaxime (2 g every 8 hours) plus metronidazole (0.5 g intravenously every 8 hours) for 5 to 10 days was compared in 94 patients with serious intra-abdominal infection who required surgery. Eighty-three patients had an evaluable clinical response. Significantly more patients in the meropenem group had a satisfactory clinical response at the end of treatment (41/43 [95.3%] vs 30/40 [75.0%]; p = 0.008). The bacteriological response was also higher in the meropenem group (31/33 vs 26/32). In the bacteriologically evaluable population, a satisfactory clinical response was observed in 31/33 of those who received meropenem compared to 24/32 of the cefotaxime/metronidazole recipients (p = 0.03). Empirical meropenem monotherapy should prove a useful alternative to the currently standard combination treatment for serious intraabdominal infections.