Treatment of complicated intra-abdominal infections in the era of multi-drug resistant bacteria

Optimized Charge/Hydrophobicity Balance of Antimicrobial Peptides Against Polymicrobial Abdominal Infections

Antimicrobial peptides (AMPs) potentially serve as ideal antimicrobial agents for the treatment of polymicrobial abdominal infections due to their broad-spectrum antimicrobial activity and excellent biocompatibility. However, the balance of chain length, positive charges, and hydrophobicity on the antimicrobial activity of AMPs are still far from being optimal. Herein, a series of AMPs ([KX]n-NH2, X = Ile, Leu or Phe, n = 3, 4, 5, or 6) with varied charges and hydrophobicity for the treatment of polymicrobial abdominal infections are designed. Specifically, [KI]4-NH2 peptide exhibits the best in vitro antimicrobial activity against Gram-positive and -negative bacteria, as well as fungal strains. Based on the good cell biocompatibility, [KI]4-NH2 peptide is found to have negligible in vivo toxicity at the dosage of up to 28 mg kg-1. Furthermore, great in vivo therapeutic efficacy of [KI]4-NH2 peptide against S. typhimurium is demonstrated in the mice abdominal infection model. The design of short sequence of antimicrobial peptides with a charge/hydrophobicity balanced structures provides a simple and efficient strategy for potential clinical applications of antimicrobial peptide-based biomaterials in a variety of bacterial infection diseases.

Comparative phenotypic and genotypic analysis of community-acquired and hospital-acquired intra-abdominal infections among liver transplanted patients

AIM

During liver transplantation, both hospital-acquired (HA) and community-acquired (CA) intra-abdominal infections (IAIs) are involved causing life-threatening diseases. Therefore, comparative studies of aerobic and facultative anaerobic HA-IAIs and CA-IAIs after liver transplantation surgery are necessary.

METHODS AND RESULTS

The species of detected isolates (310) from intra-abdominal fluid were identified and classified into hospital-acquired intra-abdominal infections (HA-IAIs) and community-acquired intra-abdominal infections (CA-IAIs). Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter baumannii were the most commonly detected species. The resistant phenotypes were commonly detected among the HA-IAIs; however, the virulent phenotypes were the predominant strains of CA-IAIs. Regrettably, the resistance profiles were shocking, indicating the inefficacy of monotherapy in treating these isolates. Therefore, we confirmed the use of empirical combination therapies of amikacin and meropenem for treating all IAIs (FICI ≤ 0.5). Unfortunately, the high diversity and low clonality of all identified HA and CA-IAIs were announced with D-value in the range of 0.992-1.

CONCLUSION

This diversity proves that there are infinite numbers of infection sources inside and outside healthcare centers.

Isoflurane attenuates sepsis-associated lung injury

Acute lung injury is one of major complications associated with sepsis, responsible for morbidity and mortality. Patients who suffer from acute lung injury often require respiratory support under sedations, and it would be important to know the role of sedatives in lung injury. We examined volatile anesthetic isoflurane, which is commonly used in surgical setting, but also used as an alternative sedative in intensive care settings in European countries and Canada. We found that isoflurane exposure attenuated neutrophil recruitment to the lungs in mice suffering from experimental polymicrobial abdominal sepsis. We found that isoflurane attenuated one of major neutrophil chemoattractants LTB4 mediated response via its receptor BLT1 in neutrophils. Furthermore, we have shown that isoflurane directly bound to BLT1 by a competition assay using newly developed labeled BLT1 antagonist, suggesting that isoflurane would be a BLT1 antagonist.

Effects of four different adjuvants separately combined with Aeromonas veronii inactivated vaccine on haematoimmunological state, enzymatic activity, inflammatory response and disease resistance in crucian carp

The purpose of the current study was to explore the immunomodulatory effects of different adjuvants combined with inactivated vaccines under Aeromonas veronii TH0426 infection in crucian carp. This study explored the best conditions for A. veronii as an inactivated vaccine, and included an animal safety test. Furthermore, we expressed the flagellin FlaA of the A. veronii TH0426 strain for use as an adjuvant supplemented in the diet. Crucian carp were fed 12 different experimental diets for 35 days, including the administration of 10 different adjuvants and inactivated vaccine combinations (50% aluminum hydroxide gel and inactivated vaccine combination, and inactivated vaccine with 20%, 30%, or 50% glucan, astragalus polysaccharide or flagellin), inactivated vaccine alone, and PBS control without adjuvant and inactivated vaccine. After the 42 day feeding trials, the fish were challenged with A. veronii TH0426, and the survival rate over 14 days was recorded. In addition, flagellin FlaA can be expressed normally in large amounts. All experimental groups produced higher levels of IgM serum titres than the control group in the different feeding cycles. Moreover, the activity of serum ACP, AKP, SOD, and LZM, and the expression of inflammatory factors were significantly increased in the experimental groups compared with the control group. The results of qRT-PCR analysis showed that the transcription levels of the IL-10, IL-1β, IFN-γ and TNF-α genes in heart, liver, spleen and kidney tissues were significantly enhanced by adjuvant treatment, indicating that the addition of adjuvants can significantly promote the body's inflammatory response. In addition, the phagocytic activity of leukocytes in each adjuvant treated group was significantly enhanced compared to that in the groups without adjuvant. After the A. veronii challenge, the survival rate of all adjuvant-treated groups was significantly higher than that of the control group, and the 50% flagellin adjuvant group had the highest rate of 78.37%. Overall, our findings strongly indicate that adjuvants not only significantly improve the body's immunity, but also exhibit a strong anti-infection ability. Importantly, this work provides a new perspective for the prevention and control of aquaculture diseases.

Safety Profile of Ceftazidime-Avibactam: Pooled Data from the Adult Phase II and Phase III Clinical Trial Programme

INTRODUCTION

Ceftazidime-avibactam combines the established anti-pseudomonal cephalosporin, ceftazidime, with the novel non-β-lactam β-lactamase inhibitor, avibactam.

OBJECTIVES

The aim of this study was to evaluate the safety of ceftazidime-avibactam in adults using pooled data from two phase II (NCT00690378, NCT00752219) and five phase III (NCT01499290, NCT01726023, NCT01644643, NCT01808093 and NCT01595438/NCT01599806) clinical studies.

METHODS

Safety data from seven multicentre, randomised, active-comparator studies were pooled by study group at the patient level for descriptive analyses, comprising patients with complicated urinary tract infection (cUTI), including pyelonephritis, complicated intra-abdominal infection (cIAI), or nosocomial pneumonia (NP), including ventilator-associated pneumonia (VAP), treated with ceftazidime-avibactam ± metronidazole or comparator.

RESULTS

In total, 4050 patients (ceftazidime-avibactam ± metronidazole, n = 2024; comparator, n = 2026) were included in the pooled analysis. Adverse events (AEs) up to the last study visit occurred in 996 (49.2%) and 965 (47.6%) patients treated with ceftazidime-avibactam ± metronidazole and comparator, respectively. The most common AEs across treatment groups were diarrhoea, nausea, headache, vomiting and pyrexia. There were few discontinuations due to AEs (2.5% and 1.7% for ceftazidime-avibactam ± metronidazole and comparators, respectively). Overall rates of serious AEs were 8.7% for ceftazidime-avibactam ± metronidazole and 7.2% for comparators; respective rates of AEs with an outcome of death were 2.0% and 1.8%. AEs considered causally related to the study drug or procedures occurred in 10.7% and 9.6% of patients treated with ceftazidime-avibactam ± metronidazole and comparators; the most common drug-related AEs in both groups were diarrhoea, headache, nausea and increased alanine aminotransferase. No impact to the safety profile of ceftazidime-avibactam ± metronidazole was found with regard to intrinsic factors, such as age or renal function at baseline, or extrinsic factors, such as geographical origin. Potentially clinically significant changes in laboratory parameters were infrequent with no trends or safety concerns identified.

CONCLUSION

The observed safety profile of ceftazidime-avibactam across infection types is consistent with the established safety profile of ceftazidime monotherapy and no new safety findings were identified. This analysis supports the use of ceftazidime-avibactam as a treatment option in adults with cUTI, cIAI and NP, including VAP.

Dose optimisation based on pharmacokinetic/pharmacodynamic target of tigecycline

Tigecycline, a new first-in-class glycylcycline antibiotic, has shown promising efficacy against a broad range of micro-organisms. It is widely prescribed for various infections, with most prescriptions being considered for off-label use. However, only a few years after its approval by the US Food and Drug Administration (FDA), tigecycline is suspected of increasing all-cause mortality. Some clinicians have suggested such unfavourable outcomes correlate with inadequate drug exposure at the infection site. The pharmacokinetic/pharmacodynamic (PK/PD) profile of a drug plays an important role in predicting its antibiotic effect, which for tigecycline is determined as the ratio of area under the concentration-time curve (AUC) to minimum inhibitory concentration (MIC). In this study, PK/PD targets based on infection sites, bacterial isolates and patient populations are discussed. Generally, a higher dosage of tigecycline for the treatment of serious infections has been recommended in previous reports. However, the latest finding of tigecycline's atypical protein binding property requires consideration when recommending further use. In addition, combination therapy with other antibiotics provides another option by potentially lowering the MICs of multidrug-resistant bacteria.

Trends, Epidemiology, and Management of Multi-Drug Resistant Gram-Negative Bacterial Infections in the Hospitalized Setting

The increasing prevalence of antibiotic resistance is a threat to human health, particularly within vulnerable populations in the hospital and acute care settings. This leads to increasing healthcare costs, morbidity, and mortality. Bacteria rapidly evolve novel mechanisms of resistance and methods of antimicrobial evasion. Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter baumannii have all been identified as pathogens with particularly high rates of resistance to antibiotics, resulting in a reducing pool of available treatments for these organisms. Effectively combating this issue requires both preventative and reactive measures. Reducing the spread of resistant pathogens, as well as reducing the rate of evolution of resistance is complex. Such a task requires a more judicious use of antibiotics through a better understanding of infection epidemiology, resistance patterns, and guidelines for treatment. These goals can best be achieved through the implementation of antimicrobial stewardship programs and the development and introduction of new drugs capable of eradicating multi-drug resistant Gram-negative pathogens (MDR GNB). The purpose of this article is to review current trends in MDR Gram-negative bacterial infections in the hospitalized setting, as well as current guidelines for management. Finally, new and emerging antimicrobials, as well as future considerations for combating antibiotic resistance on a global scale are discussed.

Oral amoxicillin and amoxicillin-clavulanic acid: properties, indications and usage

BACKGROUND

Amoxicillin has been in use since the 1970s; it is the most widely used penicillin both alone and in combination with the β-lactamase clavulanic acid.

OBJECTIVES

In this narrative review, we re-examine the properties of oral amoxicillin and clavulanic acid and provide guidance on their use, with emphasis on the preferred use of amoxicillin alone.

SOURCES

Published medical literature (MEDLINE database via Pubmed).

CONTENT

While amoxicillin and clavulanic acid have similar half-lives, clavulanic acid is more protein bound and even less heat stable than amoxicillin, with primarily hepatic metabolism. It is also more strongly associated with gastrointestinal side effects, including Clostridium difficile infection, and, thus, in oral combination formulations, limits the maximum daily dose of amoxicillin that can be given. The first ratio for an amoxicillin-clavulanic acid combination was set at 4:1 due to clavulanic acid's high affinity for β-lactamases; ratios of 2:1, 7:1, 14:1 and 16:1 are currently available in various regions. Comparative effectiveness data for the different ratios are scarce. Amoxicillin-clavulanic acid is often used as empiric therapy for many of the World Health Organization's Priority Infectious Syndromes in adults and children, leading to extensive consumption, when some of these syndromes could be handled with a delayed antibiotic prescription approach or amoxicillin alone.

IMPLICATIONS

Using available epidemiological and pharmacokinetic data, we provide guidance on indications for amoxicillin versus amoxicillin-clavulanic acid and on optimal oral administration, including choice of combination ratio. More data are needed, particularly on heat stability, pharmacodynamic effects and emergence of resistance in 'real-world' clinical settings.

Antibiotic Resistance in Community-Acquired Intra-Abdominal Infections: Diabetes Mellitus as a Risk Factor

Background: Antimicrobial drug resistance in community-acquired (CA) infections is a growing problem. Knowing the local epidemiology is essential to design empirical antibiotic therapy. Therefore, we conducted this study to evaluate the resistance patterns of microorganisms isolated from surgical samples of community-acquired intra-abdominal infections (IAIs) and to determine the factors associated with resistance. Methods: We analyzed retrospectively the records of patients treated from January 2015 to June 2017 who had IAIs with positives aerobic cultures performed in the first 72 hours after admission. Surgical site infections, abdominal wall procedures, peritoneal dialysis catheters, and patients with admissions in the prior month were excluded. To identify the factors associated with resistance, we considered the resistance to the regimen recommended at our institution, ampicillin/sulbactam (AMS) plus ciprofloxacin (CIP). Results: There were 119 patients with 133 isolates, 59% women, and mean age 54 years. The main sources of infection were appendicitis (38%) and cholecystitis (20%), with 64 patients presenting a complicated IAI (cIAI), defined by the presence of peritonitis (55%). Resistance in Enterobacteriaceae was AMS 32% (6.4% intermediate resistance), CIP 31%, cefotaxime 9%, piperacillin/tazobactam (PTZ) 3%, trimethoprim/sulfamethoxazole 32%, gentamicin 9.5%, and amikacin 2%. Considering all patients, resistance to AMS + CIP was 16.8%. Factors associated with resistant to this regimen was, by univariable and multivariable analysis, the presence of diabetes mellitus (odds ratio [OR] 3.6; 95% confidence interval [CI] 1.1-11.6; p = 0.03). Female gender (OR 2.7; CI 0.9-8.4; p = 0.08) and complicated IAI (OR 2.0; CI 0.7-5.4; p = 0.17) were associated with resistance but did not reach statistical significance. Conclusion: High resistance to CIP and AMS was observed. Although the combination of AMS + CIP offers coverage for 84% of patients, PTZ should be considered as an option for patients with severe infections or diabetes mellitus. Finding factors associated with antibiotic resistance could help to select empirical therapy for CA IAIs better.

Outcomes of a Single Surgeon-Based Transanal-Total Mesorectal Excision (TATME) for Rectal Cancer

BACKGROUND

Several studies have shown the transanal total mesorectal excision (TATME) is emerging as a safe and effective technique for proctectomy. The majority of these studies to date, however, is based on procedures done in centers with teams of two surgeons working simultaneously. Few were performed by single-surgeon teams with sizeable case load. The objective of our study was to identify the feasibility and safety of a single-surgeon TATME.

METHODS

Chart review of prospectively collected data on 27 patients who underwent TATME at our institution from June 2015 to September 2016 were included in this study. Indications for TATME included mid and low rectal cancers. Only patients who underwent surgery for neoplastic lesions were included in the study. Outcomes assessed included mesorectal integrity, margin status, operative time, complications, morbidity, LOS, and 30-day readmission.

RESULTS

A total of 27 cases were available for inclusion. A single surgeon performed all procedures. The average BMI was 27.2 ± 1.3 kg/m². The average tumor distance from anal verge was 6.8 ± 0.6 cm. The median operative time was 283 min. No intraoperative complications, including injuries and conversions, occurred. Circumferential resection margin (CRM) and distal resection margin (DRM) were R0 in 96 and 100% of patients, respectively. Mesorectal integrity was "Complete" in 67% and "Near complete" in 33% of patients. There were no incomplete specimens. The total lymph node (LN) harvest was 26 ± 2. The average LOS was 4 days for 75% of all patients. There were no mortalities. The overall morbidity was 33% (9/27). There were 4/27 anastomotic leaks, one required a laparoscopic ileostomy, one had laparoscopic drainage of an abscess, and the other two were endoscopically washed and trans-rectal drains inserted.

CONCLUSION

TATME performed by a one-surgeon team is oncologically adequate, and it is safe and feasible. Morbidities are comparable with existing literature data from two-surgeon teams. In addition, resection margins, mesorectal integrity, and LN harvests are also comparable or superior to some of the existing studies.

The efficacy and safety of tazobactam/ceftolozane in combination with metronidazole in Japanese patients with complicated intra-abdominal infections

Tazobactam/ceftolozane, a novel antimicrobial therapy, is active against Pseudomonas aeruginosa and most extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae. We report the results of the efficacy and safety of tazobactam/ceftolozane in Japanese patients with complicated intra-abdominal infections (cIAI). A multicenter, open-label, noncomparative study (MK-7625A Protocol 013, ClinicalTrials.gov Identifier: NCT02739997) to investigate the efficacy and safety of tazobactam/ceftolozane used in combination with metronidazole in Japanese patients with cIAI was conducted. One hundred Japanese patients with cIAI received tazobactam/ceftolozane 1.5 g (tazobactam 0.5 g/ceftolozane 1 g) plus metronidazole 500 mg intravenously every 8 h for 60 min for 4-14 days. The clinical response rate at the Test-of-Cure visit (TOC; Day 28 ± 2 days) was 92.0% (81/88 subjects). By disease type, the clinical response rates were 92.3% (24/26) for cholecystitis, 100% (6/6) for liver abscess, 93.5% (58/62) for intra-abdominal abscess and 90.2% (55/61) for peritonitis. The per-subject microbiological response rate at the TOC was 90.2% (55/61). Per-pathogen microbiological response rates in the most common baseline pathogens were Escherichia coli 90.2% (37/41), Kebsiella pneumoniae 91.7% (11/12), Streptococcus anginosus 100% (11/11), Streptococcus constellatus 90.0% (9/10) and Bacteroides fragilis 95.2% (20/21). The most common drug-related AEs were aspartate aminotransferase increased (11.0%) and alanine aminotransferase increased (9.0%). No serious drug-related AE was reported during the study. The favorable effect of tazobactam/ceftolozane in the treatment of cIAI suggests that the agent will be useful in clinical practice in Japan.

Bacterial Whole Cell Typing by Mass Spectra Pattern Matching with Bootstrapping Assessment

Bacterial typing is of great importance in clinical diagnosis, environmental monitoring, food safety analysis, and biological research. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is now widely used to analyze bacterial samples. Identification of bacteria at the species level can be realized by matching the mass spectra of samples against a library of mass spectra of known bacteria. Nevertheless, in order to reasonably type bacteria, identification accuracy should be further improved. Herein, we propose a new framework to the identification and assessment for MALDI-MS based bacterial analysis. Our approach combines new measures for spectra similarity and a novel bootstrapping assessment. We tested our approach on a general data set containing the mass spectra of 1741 strains of bacteria and another challenging data set containing 250 strains, including 40 strains in the Bacillus cereus group that were previously claimed to be impossible to resolve by MALDI-MS. With the bootstrapping assessment, we achieved much more reliable predictions at both the genus and species level, and enabled to resolve the Bacillus cereus group. To the best of the authors' knowledge, our method is the first to provide a statistical assessment to MALDI-MS based bacterial typing that could lead to more reliable bacterial typing.

Recommendations for intra-abdominal infections consensus report

Guidelines include the recommendations of experts from various specialties within a topic in consideration of data specific to each country. However, to date there has not been a guideline standardizing the nomenclature and offering recommendations for intra-abdominal infections (IAIs) in Turkey. This is mainly due to the paucity of laboratory studies regarding the clinical diagnosis and treatment of IAIs or the sensitivity of microorganisms isolated from patients with IAIs. However, due to the diversification of host characteristics and advancements in technological treatment methods, it has become imperative to 'speak a common language'. For this purpose May 2015, a group of 15 experts in intra-abdominal infections, under the leadership of the Infectious Diseases and Clinical Microbiology Specialty Society of Turkey (EKMUD) and with representatives from the Turkish Surgical Association, Turkish Society of Colon and Rectal Surgery, Hernia Society, Turkish Society of Hepato-pancreato-biliary Surgery, and the Turkish Society of Hospital Infections and Control, was formed to analyze relevant studies in the literature. Ultimately, the suggestions for adults found in this consensus report were developed using available data from Turkey, referring predominantly to the 2010 guidelines for diagnosing and managing complicated IAIs in adults and children by the Infectious Diseases Society of America (IDSA) and the Surgical Infection Society. The recommendations are presented in two sections, from the initial diagnostic evaluation of patients to the treatment approach for IAI. This Consensus Report was presented at the EKMUD 2016 Congress in Antalya and was subsequently opened for suggestions on the official websites of the Infectious Diseases and Clinical Microbiology Specialty Society of Turkey and Turkish Surgical Association for one month. The manuscript was revised according to the feedback received.

Use of Cepheid Xpert Carba-R® for Rapid Detection of Carbapenemase-Producing Bacteria in Abdominal Septic Patients Admitted to Intensive Care Unit

Early institution of effective antibiotic therapy and source control are pivotal to improve survival of abdominal septic patients. Xpert® Carba-R is a real time polymerase chain reaction assay for rapid detection and differentiation of five genes (blaKPC, blaVIM, blaOXA-48, blaIMP-1, blaNDM) responsible for carbapenem resistance. We performed an observational study investigating the clinical usefulness and applicability of Xpert® Carba-R to detect carbapenem resistance in abdominal septic patients admitted to intensive care unit. We compared the results of Xpert® Carba-R with standard microbiological culture. We collected a set of two rectal/stomia swabs and two swabs from abdominal drainage fluid for each patient. We included 20 patients for a total of 45 comparisons between the two methods. In our clinical setting, the overall performance of Xpert® Carba-R for detection of carbapenem resistance in the presence of genes detectable and non-detectable by the method was: sensitivity 50% (95% CI 24.6-75.3); specificity 93.1% (95% CI 77.2-99.1); positive predictive value (PPV) 80% (95% CI 44.4-97.5); negative predictive value (NPV) 77.1% (95% CI 56.9-89.6). The inter-rater agreement was 0.47 (SE 0.14; 95% CI 0.20-0.74). When considering the only 5 mechanisms of resistance detected by both methods, the overall diagnostic performance was: sensitivity 100% (95% CI 69.1-100), specificity 94.2 (95% CI 80.8-99.3), PPV 83.3 (95% CI 59.6-97.9) and NPV 100% (95% CI 89.4-100). The inter-rater agreement was 0.88 (SE 0.08; 95% CI 0.71-1). Xpert® Carba-R may be considered an additional diagnostic tool for early diagnosis of carbapenem resistance in abdominal septic patients. Clinicians should be aware of their epidemiology before its introduction in the diagnostic protocol of their intensive care units.

Diverting ileostomy in laparoscopic rectal cancer surgery: high price of protection

BACKGROUND

Anastomotic leakage presents the most feared complication after low anterior resection (LAR). A proximal diversion of the gastrointestinal tract is recommended to avoid septic complications of anastomotic leakage. The aim of the present study was to evaluate the benefits and risks of diverting ileostomy (DI) created during laparoscopic LAR because of low rectal cancer.

METHODS

This was a retrospective clinical cohort study conducted to assess outcomes of laparoscopic LAR with/without DI in a single institution within a 6-year period.

RESULTS

In total, 151 patients were enrolled in the study (73 patients without DI, 78 patients with DI). There were no significant differences between both groups regarding demographic and clinical features. Overall 30-day morbidity rates were significantly lower in patients without DI (23.3 vs. 42.3 %, P = 0.013). Symptomatic anastomotic leakage occurred more frequently in patients without DI (9.6 vs. 2.5 %, P = 0.090); surgical intervention was needed in 6.8 % of patients without DI. Post-operative hospital stay was significantly longer in the group of patients with DI (11.3 ± 8.5 vs. 8.1 ± 6.9 days, P = 0.013). Stoma-related complications occurred in 42 of 78 (53.8 %) patients with DI; some patients had more than one complication. Acute surgery was needed in 9 patients (11.5 %) because of DI-related complications. Small bowel obstruction due to DI semi-rotation around its longitudinal axis was seen in 3 patients (3.8 %) and presents a distinct complication of DI laparoscopic construction. The mean interval between LAR and DI reversal was more than 8 months; only 19.2 % of patients were reversed without delay (≤4 months). Morbidity after DI reversal was 16.6 %; re-laparotomy was necessary in 2.5 % of patients.

CONCLUSIONS

The present study indicates that DI protects low rectal anastomosis from septic complications at a cost of many stoma-related complications, substantial risk of acute surgery necessity and long stoma periods coupled with decreased quality of life.

Treatment Modalities and Antimicrobial Stewardship Initiatives in the Management of Intra-Abdominal Infections

Antimicrobial stewardship programs (ASPs) focus on improving the utilization of broad spectrum antibiotics to decrease the incidence of multidrug-resistant Gram positive and Gram negative pathogens. Hospital admission for both medical and surgical intra-abdominal infections (IAIs) commonly results in the empiric use of broad spectrum antibiotics such as fluoroquinolones, beta-lactam beta-lactamase inhibitors, and carbapenems that can select for resistant organisms. This review will discuss the management of uncomplicated and complicated IAIs as well as highlight stewardship initiatives focusing on the proper use of broad spectrum antibiotics.

Clinical characteristics and antimicrobial patterns in complicated intra-abdominal infections: a 6-year epidemiological study in southern China

Complicated intra-abdominal infection (cIAIs) are a common and important cause of morbidity worldwide. In this study, the clinical features, microbiological profiles, antimicrobial patterns and treatments of 3233 cIAI patients (mean age, 47.6 years; 54.7% male) with 3531 hospitalisations from 2008-2013 were retrospectively investigated. The most commonly isolated bacteria were Escherichia coli (47.6%), Klebsiella pneumoniae (16.9%), Enterococcus faecalis (10.4%) and Pseudomonas aeruginosa (8.8%). Ciprofloxacin, aminoglycoside (gentamicin), piperacillin/tazobactam and carbapenems exhibited activity against 53%, 76%, 88% and 100% of extended-spectrum β-lactamase (ESBL)-positive Enterobacteriaceae isolates, respectively. Pseudomonas aeruginosa isolates exhibited 100%, 95%, 88%, 71% and 76% susceptibility to aminoglycoside (gentamicin), ciprofloxacin, meropenem, imipenem and ceftazidime, respectively, and Enterococcus remained 100% susceptible to vancomycin and linezolid. β-Lactam antibacterials other than penicillin (specifically third-generation cephalosporins) and imidazole derivatives (ornidazole and metronidazole) were the most common first-line treatments. Patients subjected to regimen change after initial antibiotic treatment had predisposing conditions (e.g. older age, more severe co-morbidities) and a higher incidence of P. aeruginosa infection; in addition, these patients encountered a higher average cost of care and worse clinical outcomes compared with those without medication modification. Taken together, these findings indicate the importance of appropriate initial empirical therapy and suggest the use of combination therapy comprising cephalosporins and metronidazole.

Antimicrobials: a global alliance for optimizing their rational use in intra-abdominal infections (AGORA)

Intra-abdominal infections (IAI) are an important cause of morbidity and are frequently associated with poor prognosis, particularly in high-risk patients. The cornerstones in the management of complicated IAIs are timely effective source control with appropriate antimicrobial therapy. Empiric antimicrobial therapy is important in the management of intra-abdominal infections and must be broad enough to cover all likely organisms because inappropriate initial antimicrobial therapy is associated with poor patient outcomes and the development of bacterial resistance. The overuse of antimicrobials is widely accepted as a major driver of some emerging infections (such as C. difficile), the selection of resistant pathogens in individual patients, and for the continued development of antimicrobial resistance globally. The growing emergence of multi-drug resistant organisms and the limited development of new agents available to counteract them have caused an impending crisis with alarming implications, especially with regards to Gram-negative bacteria. An international task force from 79 different countries has joined this project by sharing a document on the rational use of antimicrobials for patients with IAIs. The project has been termed AGORA (Antimicrobials: A Global Alliance for Optimizing their Rational Use in Intra-Abdominal Infections). The authors hope that AGORA, involving many of the world's leading experts, can actively raise awareness in health workers and can improve prescribing behavior in treating IAIs.

The Challenge of Antimicrobial Resistance in Managing Intra-Abdominal Infections

BACKGROUND

In recent years, there has been a worldwide increase in infections caused by microorganisms resistant to multiple antimicrobial agents.

METHODS

In the past few decades, an increased prevalence of infections caused by antibiotic-resistant pathogens, including Enterococcus spp., carbapenem-resistant Pseudomonas aeruginosa and Acinetobacter baumannii, extended-spectrum β-lactamase (ESBL)-producing Escherichia coli and Klebsiella spp., carbapenemase-producing Klebsiella pneumoniae, and resistant Candida spp., also has been observed among intra-abdominal infections (IAIs).

RESULTS

The increasing prevalence of multi-drug resistance is responsible for a substantial increase in morbidity and mortality rates associated with IAIs.

CONCLUSIONS

It is necessary for every surgeon treating IAIs to understand the underlying epidemiology and clinical consequences of antimicrobial resistance. Emergence of drug resistance, combined with the lack of new agents in the drug development pipeline, indicates that judicious antimicrobial management will be necessary to preserve the utility of the drugs available currently.

Ceftolozane/Tazobactam Plus Metronidazole for Complicated Intra-abdominal Infections in an Era of Multidrug Resistance: Results From a Randomized, Double-Blind, Phase 3 Trial (ASPECT-cIAI)

This phase 3 trial compared ceftolozane/tazobactam plus metronidazole vs meropenem for the treatment of complicated intra-abdominal infections. Ceftolozane/tazobactam plus metronidazole was noninferior to meropenem. High rates of presumed microbiological eradication of Enterobacteriaceae and Pseudomonas aeruginosa were found with both regimens.

Background. Increasing antimicrobial resistance among pathogens causing complicated intra-abdominal infections (cIAIs) supports the development of new antimicrobials. Ceftolozane/tazobactam, a novel antimicrobial therapy, is active against multidrug-resistant Pseudomonas aeruginosa and most extended-spectrum β-lactamase (ESBL)–producing Enterobacteriaceae.

Methods. ASPECT-cIAI (Assessment of the Safety Profile and Efficacy of Ceftolozane/Tazobactam in Complicated Intra-abdominal Infections) was a prospective, randomized, double-blind trial. Hospitalized patients with cIAI received either ceftolozane/tazobactam (1.5 g) plus metronidazole (500 mg) every 8 hours or meropenem (1 g) every 8 hours intravenously for 4–14 days. The prospectively defined objectives were to demonstrate statistical noninferiority in clinical cure rates at the test-of-cure visit (24–32 days from start of therapy) in the microbiological intent-to-treat (primary) and microbiologically evaluable (secondary) populations using a noninferiority margin of 10%. Microbiological outcomes and safety were also evaluated.

Results. Ceftolozane/tazobactam plus metronidazole was noninferior to meropenem in the primary (83.0% [323/389] vs 87.3% [364/417]; weighted difference, −4.2%; 95% confidence interval [CI], −8.91 to .54) and secondary (94.2% [259/275] vs 94.7% [304/321]; weighted difference, −1.0%; 95% CI, −4.52 to 2.59) endpoints, meeting the prespecified noninferiority margin. In patients with ESBL-producing Enterobacteriaceae, clinical cure rates were 95.8% (23/24) and 88.5% (23/26) in the ceftolozane/tazobactam plus metronidazole and meropenem groups, respectively, and 100% (13/13) and 72.7% (8/11) in patients with CTX-M-14/15 ESBLs. The frequency of adverse events (AEs) was similar in both treatment groups (44.0% vs 42.7%); the most common AEs in either group were nausea and diarrhea.

Conclusions. Treatment with ceftolozane/tazobactam plus metronidazole was noninferior to meropenem in adult patients with cIAI, including infections caused by multidrug-resistant pathogens.

Clinical Trials Registration. NCT01445665 and NCT01445678.

New amphiphilic neamine derivatives active against resistant Pseudomonas aeruginosa and their interactions with lipopolysaccharides

The development of novel antimicrobial agents is urgently required to curb the widespread emergence of multidrug-resistant bacteria like colistin-resistant Pseudomonas aeruginosa. We previously synthesized a series of amphiphilic neamine derivatives active against bacterial membranes, among which 3',6-di-O-[(2"-naphthyl)propyl]neamine (3',6-di2NP), 3',6-di-O-[(2"-naphthyl)butyl]neamine (3',6-di2NB), and 3',6-di-O-nonylneamine (3',6-diNn) showed high levels of activity and low levels of cytotoxicity (L. Zimmermann et al., J. Med. Chem. 56:7691-7705, 2013). We have now further characterized the activity of these derivatives against colistin-resistant P. aeruginosa and studied their mode of action; specifically, we characterized their ability to interact with lipopolysaccharide (LPS) and to alter the bacterial outer membrane (OM). The three amphiphilic neamine derivatives were active against clinical colistin-resistant strains (MICs, about 2 to 8 μg/ml), The most active one (3',6-diNn) was bactericidal at its MIC and inhibited biofilm formation at 2-fold its MIC. They cooperatively bound to LPSs, increasing the outer membrane permeability. Grafting long and linear alkyl chains (nonyl) optimized binding to LPS and outer membrane permeabilization. The effects of amphiphilic neamine derivatives on LPS micelles suggest changes in the cross-bridging of lipopolysaccharides and disordering in the hydrophobic core of the micelles. The molecular shape of the 3',6-dialkyl neamine derivatives induced by the nature of the grafted hydrophobic moieties (naphthylalkyl instead of alkyl) and the flexibility of the hydrophobic moiety are critical for their fluidifying effect and their ability to displace cations bridging LPS. Results from this work could be exploited for the development of new amphiphilic neamine derivatives active against colistin-resistant P. aeruginosa.

Antioxidant supplementation enhances bacterial peritonitis in mice by inhibiting phagocytosis

Antioxidants are known to exhibit numerous health benefits including anti-ageing, anti-apoptotic and immuno-stimulatory effects. However, we present the data showing counterproductive effects of therapeutically relevant antioxidants on bacterial clearance by the immune system in a murine peritonitic model. The antioxidants ascorbic acid, glutathione and N-acetylcysteine augmented morbidity and mortality in mice carrying Eshcerichia coli-induced acute bacterial peritonitis. Treatment of peritonitic mice with antioxidants significantly increased their bacterial load in the range of 0.3-2 logs. Antioxidant administration to peritonitic mice resulted in decreased numbers of macrophages, B-cells and dendritic cells at the primary site of infection and increased neutrophil infiltration. Serum TNF-α levels were also decreased in antioxidant-treated peritonitic mice. In vitro experiments showed that antioxidants reduced the phagocytic efficacy of peritoneal macrophages by ~60-75% and also decreased E. coli-induced oxidative burst in macrophages cells. Taken together, our data indicate that the antioxidants increased the severity of peritonitis by decreasing the phagocytic efficiency, oxidative burst, and TNF-α production, and increasing neutrophil infiltration. Based on these results, we propose that antioxidant supplementation during the course of bacterial infection is not recommended as it could be detrimental for the host. In addition, the present study underlines the importance of timing and context of antioxidant administration rather than indiscriminate usage to gain the best possible therapeutic advantage of these redox compounds.

Intraabdominal Infections in the Intensive Care Unit

Intraabdominal infections are frequent and dangerous entity in intensive care units. Mortality and morbidity are high, causes are numerous, and treatment options are variable. The intensivist is challenged to recognize and treat intraabdominal infections in a timely fashion to prevent complications and death. Diagnosis of intraabdominal infection is often complicated by confounding underlying disease or masked by overall comorbidity. Current research describes a wide heterogeneity of patient populations, making it difficult to suggest a general treatment regimen and stressing the need of an individualized approach to decision making. Early focus-oriented intervention and antibiotic coverage tailored to the individual patient and hospital is warranted.

Bacteribilia with resistant microorganisms after preoperative biliary drainage--the influence of bacteria on postoperative outcome

BACKGROUND

In pancreatic surgery, preoperative biliary drainage (PBD) leads to bacteribilia. Whether positive bile duct cultures are associated with a higher postoperative morbidity might be related to the resistance of the species isolated from bile.

STUDY

Intraoperative bile duct cultures were collected from all patients who underwent pancreatic surgery. Postoperative morbidity was analyzed according to the species and the resistance found on bile duct cultures.

RESULTS

Fifty-five percent (166/301) of patients had PBD, while 45% (135/301) underwent primary operation. PBD was associated with a positive bile duct culture in 87% (144/166) versus 21% (28/135) in patients without PBD (p = 0.001) and polymicrobial infections in 53% (88/166) versus 6% (8/135) (p = 0.001). Postoperative morbidity was 40% (121/301); mortality was 3% (9/301). PBD was not associated with morbidity and mortality, but resistant species on bile duct cultures lead to significantly more postoperative complications, 54% (25/46) versus 38% (96/255) (p = 0.033), with significantly more antibiotic therapies.

CONCLUSION

PBD is associated with polymicrobial infections with resistant microorganisms, resulting in more postoperative complications. Since PBD cannot always be avoided, surgeons and gastroenterologists must be aware of their institutional surveillance data to identify patients at risk for postoperative complications.