2024 Clinical Practice Guideline Update by the Infectious Diseases Society of America on Complicated Intra-abdominal Infections: Utility of Blood Cultures in Adults, Children, and Pregnant People.

This article is part of a clinical practice guideline update on the risk assessment, diagnostic imaging, and microbiological evaluation of complicated intra-abdominal infections in adults, children, and pregnant people, developed by the Infectious Diseases Society of America. In this guideline, the panel provides recommendations for obtaining blood cultures in patients with known or suspected intra-abdominal infection. The panel's recommendations are based on evidence derived from systematic literature reviews and adhere to a standardized methodology for rating the certainty of evidence and strength of recommendation according to the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) approach.

2024 Clinical Practice Guideline Update by the Infectious Diseases Society of America on Complicated Intra-abdominal Infections: Diagnostic Imaging of Suspected Acute Intra-abdominal Abscess in Adults, Children, and Pregnant People.

This article is part of a clinical practice guideline update on the risk assessment, diagnostic imaging, and microbiological evaluation of complicated intra-abdominal infections in adults, children, and pregnant people, developed by the Infectious Diseases Society of America. In this article, the panel provides recommendations for diagnostic imaging of suspected acute intra-abdominal abscess. The panel's recommendations are based on evidence derived from systematic literature reviews and adhere to a standardized methodology for rating the certainty of evidence and strength of recommendation according to the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) approach.

2024 Clinical Practice Guideline Update by the Infectious Diseases Society of America on Complicated Intra-abdominal Infections: Utility of Intra-abdominal Fluid Cultures in Adults, Children, and Pregnant People.

This paper is part of a clinical practice guideline update on the risk assessment, diagnostic imaging, and microbiological evaluation of complicated intra-abdominal infections in adults, children, and pregnant people, developed by the Infectious Diseases Society of America. In this paper, the panel provides recommendations for obtaining cultures of intra-abdominal fluid in patients with known or suspected intra-abdominal infection. The panel's recommendations are based on evidence derived from systematic literature reviews and adhere to a standardized methodology for rating the certainty of evidence and strength of recommendation according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach.

2024 Clinical Practice Guideline Update by the Infectious Diseases Society of America on Complicated Intra-abdominal Infections: Diagnostic Imaging of Suspected Acute Appendicitis in Adults, Children, and Pregnant People.

This paper is part of a clinical practice guideline update on the risk assessment, diagnostic imaging, and microbiological evaluation of complicated intra-abdominal infections in adults, children, and pregnant people, developed by the Infectious Diseases Society of America (IDSA). In this paper, the panel provides recommendations for diagnostic imaging of suspected acute appendicitis. The panel's recommendations are based on evidence derived from systematic literature reviews and adhere to a standardized methodology for rating the certainty of evidence and strength of recommendation according to the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) approach.

2024 Clinical Practice Guideline Update by the Infectious Diseases Society of America on Complicated Intra-abdominal Infections: Diagnostic Imaging of Suspected Acute Diverticulitis in Adults and Pregnant People.

This paper is part of a clinical practice guideline update on the risk assessment, diagnostic imaging, and microbiological evaluation of complicated intra-abdominal infections in adults, children, and pregnant people, developed by the Infectious Diseases Society of America. In this paper, the panel provides recommendations for diagnostic imaging of suspected acute diverticulitis. The panel's recommendations are based on evidence derived from systematic literature reviews and adhere to a standardized methodology for rating the certainty of evidence and strength of recommendation according to the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) approach.

2024 Clinical Practice Guideline Update by the Infectious Diseases Society of America on Complicated Intra-abdominal Infections: Risk Assessment in Adults and Children.

This paper is part of a clinical practice guideline update on the risk assessment, diagnostic imaging, and microbiological evaluation of complicated intra-abdominal infections in adults, children, and pregnant people, developed by the Infectious Diseases Society of America. In this paper, the panel provides a recommendation for risk stratification according to severity of illness score. The panel's recommendation is based on evidence derived from systematic literature reviews and adheres to a standardized methodology for rating the certainty of evidence and strength of recommendation according to the GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) approach.

2024 Clinical Practice Guideline Update by the Infectious Diseases Society of America on Complicated Intra-abdominal Infections: Risk Assessment, Diagnostic Imaging, and Microbiological Evaluation in Adults, Children, and Pregnant People.

As the first part of an update to the clinical practice guideline on the diagnosis and management of complicated intra-abdominal infections in adults, children, and pregnant people, developed by the Infectious Diseases Society of America, the panel presents 21 updated recommendations. These recommendations span risk assessment, diagnostic imaging, and microbiological evaluation. The panel's recommendations are based on evidence derived from systematic literature reviews and adhere to a standardized methodology for rating the certainty of evidence and strength of recommendation according to the GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) approach.

Utility of paired plasma and drainage fluid mNGS in diagnosing acute intra-abdominal infections with sepsis.

BACKGROUND: Metagenomic next-generation sequencing (mNGS) has been increasingly applied in sepsis. We aimed to evaluate the diagnostic and therapeutic utility of mNGS of paired plasma and peritoneal drainage (PD) fluid samples in comparison to culture-based microbiological tests (CMTs) among critically ill patients with suspected acute intra-abdominal infections (IAIs). METHODS: We conducted a prospective study from October 2021 to December 2022 enrolling septic patients with suspected IAIs (n = 111). Pairwise CMTs and mNGS of plasma and PD fluid were sent for pathogen detection. The mNGS group underwent therapeutic regimen adjustment based on mNGS results for better treatment. The microbial community structure, clinical features, antibiotic use and prognoses of the patients were analyzed. RESULTS: Higher positivity rates were observed with mNGS versus CMTs for both PD fluid (90.0% vs. 48.3%, p < 0.005) and plasma (76.7% vs. 1.6%, p < 0.005). 90% of enrolled patients had clues of suspected pathogens combining mNGS and CMT methods. Gram-negative pathogens consist of most intra-abdominal pathogens, including a great variety of anaerobes represented by Bacteroides and Clostridium. Patients with matched plasma- and PD-mNGS results had higher mortality and sepsis severity. Reduced usage of carbapenem (30.0% vs. 49.4%, p < 0.05) and duration of anti-MRSA treatment (5.1 ± 3.3 vs. 7.0 ± 8.4 days, p < 0.05) was shown in the mNGS group in our study. CONCLUSIONS: Pairwise plasma and PD fluid mNGS improves microbiological diagnosis compared to CMTs for acute IAI. Combining plasma and PD mNGS could predict poor prognosis. mNGS may enable optimize empirical antibiotic use.

Postoperative morbidity following Hartmann's procedure in comparison to anterior resection and abdominoperineal resection for rectal cancer-a population-based study.

AIM: There is ongoing controversy regarding the extent to which Hartmann's procedure (HP) should be used in rectal cancer treatment. This study was designed to investigate 30-day postoperative morbidity and mortality following HP, anterior resection (AR) and abdominoperineal resection (APR) for rectal cancer using a national registry. METHODS: All patients operated for rectal cancer, tumour height 5-15 cm, between the years 2010 and 2017, were identified through the Swedish colorectal cancer registry. RESULTS: A total of 8476 patients were included: 1210 (14%) undergoing HP, 5406 (64%) AR and 1860 (22%) APR. HP was associated with an increased risk of intra-abdominal infection (OR 1.7, CI 1.26-2.28, P = 0.0004) compared to AR and APR, while APR was related to an increased risk of overall complications (OR 1.18, CI 1.01-1.40, P = 0.040). No significant difference was observed in the rate of reoperations and readmissions between HP, AR and APR, and type of surgical procedure was not a risk factor for 30-day mortality. Findings from a subgroup analysis of patients with a tumour 5-7 cm from the anal verge revealed that HP was not associated with increased risk for complications or 30-day mortality. CONCLUSIONS: For patients where AR is not appropriate HP is a valid alternative with a favourable outcome. APR was associated with the highest overall 30-day complication rate.

Microbiological profiles and clinical outcomes of critically ill surgical patients with lower gastrointestinal perforation in Japan: a single-center retrospective observational study.

BACKGROUND: Lower gastrointestinal perforation (LGP) is a surgical emergency disease that can result in secondary bacterial peritonitis. Microbiological studies on LGP are rare. The present study aimed to ascertain the microbiological profile of LGP in patients admitted to the intensive care unit (ICU) at our institute after surgery. In addition, we investigated whether initial empirical therapy with vancomycin was associated with in-hospital mortality, duration of ICU stay, and duration of ventilator support. METHODS: This single-center, retrospective, observational study was conducted at Kobe City Medical Center General Hospital, Japan. The study population included all patients diagnosed with LGP who were admitted to the ICU after emergency surgery between 2017 and 2023. The primary outcome assessed was the microbiological profile of microorganisms isolated from ascites fluid and blood of the participants. The secondary end-points were in-hospital mortality, duration of ICU stay, and duration of ventilator support. We performed univariate and multivariate regression analyses to evaluate the end-points. RESULTS: During the study period, 89 patients were included in the analysis. The most commonly identified pathogen from the ascites cultures was Escherichia coli (65.2%), followed by Enterococcus spp. (51.7%). E. faecium was identified in 16 (18.0%) ascites samples. The microbiological profile of critically ill patients with LGP admitted to the ICU after surgery was similar to that of previous studies on intra-abdominal infection (IAI). Therefore, the initial empirical therapy in the IAI guidelines is more appropriate for LGP. Multivariate regression analysis suggested that the combination of initial empirical therapy with vancomycin was not associated with in-hospital mortality (odds ratio [OR] = 0.96, 95% confidence interval [CI] 0.23-3.00, p = 0.955), duration of ICU stay (coefficient=-0.92, 95% CI -3.04-1.21, p = 0.393), or duration of ventilator-support (coefficient=-9.03, 95%CI -49.69-31.63, p = 0.659). CONCLUSION: The microbiological profile of critically ill patients with LGP admitted to the ICU after surgery was similar to that of previous studies on IAI. However, the frequency of E. faecium in the present study was higher than that in previous studies. Initial empirical therapy with drugs such as meropenem in combination with vancomycin for E. faecium was not associated with in-hospital mortality, duration of ICU stay, and duration of ventilator support, after adjusting for confounding factors.

Effect of preoperative frailty on postoperative infectious complications and prognosis in patients with colorectal cancer: a propensity score matching study.

BACKGROUND: Few studies have explored the impact of preoperative frailty on infectious complications in patients with a diagnosis of colorectal cancer (CRC). Therefore, this study aimed to investigate the effect of preoperative frailty on postoperative infectious complications and prognosis in patients with CRC using propensity score matching (PSM). METHODS: This prospective single-centre observational cohort study included 245 patients who underwent CRC surgery at the Department of Gastrointestinal Surgery, The Affiliated Lianyungang Hospital of Xuzhou Medical University between August 2021 to May 2023. Patients were categorised into two groups: frail and non-frail. They were matched for confounders and 1:1 closest matching was performed using PSM. Rates of infectious complications, intensive care unit (ICU) admission, 30-day mortality, and 90-day mortality, as well as postoperative length of hospital stay, total length of hospital stay, and hospital costs, were compared between the two groups. Binary logistic regression using data following PSM to explore independent factors for relevant outcome measures. RESULTS: After PSM, each confounding factor was evenly distributed between groups, and 75 pairs of patients were successfully matched. The incidence of intra-abdominal infectious complications was significantly higher in the frail group than in the non-frail group (10.7% vs. 1.3%, P < 0.05). There were no significant differences in ICU admission rate, postoperative length of hospital stay, total length of hospital stay, hospital costs, 30-day mortality rate, or 90-day mortality rate between the two groups (P > 0.05). Our logistic regression analysis result showed that preoperative frailty (OR = 12.014; 95% CI: 1.334-108.197; P = 0.027) was an independent factor for intra-abdominal infection. CONCLUSIONS: The presence of preoperative frailty elevated the risk of postoperative intra-abdominal infectious complications in patients undergoing CRC surgery. Therefore, medical staff should assess preoperative frailty in patients with CRC early and provide targeted prehabilitation interventions.

Perioperative pancreaticoduodenectomy management strategy focusing on postoperative early drain colonization.

PURPOSE: Pancreatoduodenectomy (PD) is a highly invasive procedure. Intra-abdominal infections and pancreatic fistulas are strongly correlated complications. In the present study, we identified the risk factors for postoperative early drain colonization (POEDC) and established a perioperative management strategy. METHODS: A total of 205 patients who underwent pancreatoduodenectomy were included in the study. POEDC was defined as a positive drain fluid culture before postoperative day (POD) 4. We retrospectively investigated the correlation between POEDC, postoperative outcomes, and clinical factors. RESULTS: POEDC was observed in 26 patients (12.6%) with poor postoperative outcomes, including pancreatic fistulas (P < 0.001). A multivariate analysis demonstrated a correlation between these postoperative outcomes and the age (P = 0.002), body mass index (BMI) (P = 0.002), procalcitonin (PCT) level (P < 0.001), and drain amylase level on POD 1 (P = 0.032). Enterococcus was detected most frequently, being found in 15 patients. CONCLUSION: We observed a strong correlation between POEDC and poor postoperative outcomes. The BMI, age, and PCT and drain amylase level on POD 1 should be considered POEDC risk factors, with the need to propose an antibiotic perioperative strategy. POEDC control may represent the key to improving postoperative outcomes after PD.

Clinical and microbiological characteristics of Ruminococcus gnavus bacteremia and intra-abdominal infection.

OBJECTIVES: Ruminococcus gnavus is a rare human pathogen, and clinical data on R. gnavus infection are insufficient. This retrospective study aimed to investigate the clinical characteristics of R. gnavus infections. METHODS: This study included 13 cases of bacteremia and three cases of non-bacteremia infections caused by R. gnavus. We evaluated the patient data, infection source, clinical outcomes, and antimicrobial susceptibility of R. gnavus isolates for these cases. RESULTS: The median age of patients was 75 years (range 47-95), and eight patients were female. Twelve cases were presumed to have an intra-abdominal infection source, and the remaining four cases had an unknown infection source. The most common underlying conditions were immunosuppression (seven cases), solid tumors (seven cases), and history of gastrointestinal surgery (five cases). Thirteen patients exhibited gastrointestinal problems (dysfunction, bleeding, intra-abdominal infection, or inflammation). Multiple pathogens were observed in six cases, and fatal outcomes were recorded in three cases. Antimicrobial susceptibility data were available for eight isolates, all of which exhibited low minimum inhibitory concentrations to penicillin (≤0.03 µg/mL), ampicillin-sulbactam (≤0.5 µg/mL), piperacillin-tazobactam (≤4 µg/mL), and metronidazole (≤0.5-1 µg/mL). CONCLUSION: Ruminococcus gnavus is frequently associated with an intra-abdominal infection source, and treatment strategies should consider the possibility of multiple pathogens.

Contradictory Recommendation in the Guideline for Antibiotic Prescription.

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

Protection against lethal sepsis following immunization with Candida species varies by isolate and inversely correlates with bone marrow tissue damage.

Protection against lethal Candida albicans (Ca)/Staphylococcus aureus (Sa) intra-abdominal infection (IAI)-mediated sepsis can be achieved by a novel form of trained innate immunity (TII) involving Gr-1+ myeloid-derived suppressor cells (MDSCs) that are induced by inoculation (immunization) with low virulence Candida species [i.e., Candida dubliniensis (Cd)] that infiltrate the bone marrow (BM). In contrast, more virulent Candida species (i.e., C. albicans), even at sub-lethal inocula, fail to induce similar levels of protection. The purpose of the present study was to test the hypothesis that the level of TII-mediated protection induced by Ca strains inversely correlates with damage in the BM as a reflection of virulence. Mice were immunized by intraperitoneal inoculation with several parental and mutant strains of C. albicans deficient in virulence factors (hyphal formation and candidalysin production), followed by an intraperitoneal Ca/Sa challenge 14 d later and monitored for sepsis and mortality. Whole femur bones were collected 24 h and 13 d after immunization and assessed for BM tissue/cellular damage via ferroptosis and histology. While immunization with standard but not sub-lethal inocula of most wild-type C. albicans strains resulted in considerable mortality, protection against lethal Ca/Sa IAI challenge varied by strain was usually less than that for C. dubliniensis, with no differences observed between parental and corresponding mutants. Finally, levels of protection afforded by the Ca strains were inversely correlated with BM tissue damage (R 2 = -0.773). TII-mediated protection against lethal Ca/Sa sepsis induced by Candida strain immunization inversely correlates with BM tissue/cellular damage as a reflection of localized virulence.

Farnesol remodels the peritoneal cavity immune environment influencing Candida albicans pathogenesis during intra-abdominal infection.

Candida albicans is a lifelong member of the mycobiome causing mucosal candidiasis and life-threatening, systemic, and intra-abdominal disease in immunocompromised and transplant patients. Despite the clinical importance of intra-abdominal candidiasis with mortality rates between 40% and 70%, the contribution of fungal virulence factors and host immune responses to disease has not been extensively studied. Secretion of the quorum-sensing molecule, farnesol, acts as a virulence factor for C. albicans during systemic infection, while inducing local, protective innate immune responses in oral models of infection. Previously, we reported that farnesol recruits macrophages to the peritoneal cavity in mice, suggesting a role for farnesol in innate immune responses. Here, we expand on our initial findings, showing that farnesol profoundly alters the peritoneal cavity microenvironment promoting innate inflammation. Intra-peritoneal injection of farnesol stimulates rapid local death of resident peritoneal cells followed by recruitment of neutrophils and inflammatory macrophages into the peritoneal cavity and peritoneal mesothelium associated with an early increase in chemokines followed by proinflammatory cytokines. These rapid inflammatory responses to farnesol significantly increase morbidity and mortality of mice with intra-abdominal candidiasis associated with increased formation of peritoneal adhesions, despite similar rates of fungal clearance from the peritoneal cavity and retro-peritoneal organs. C. albicans ddp3Δ/ddp3Δ knockout and reconstituted strains recapitulate these findings. This indicates that farnesol may be detrimental to the host during intra-abdominal infections. Importantly, our results highlight a need to understand how C. albicans virulence factors modulate the host immune response within the peritoneum, an exceedingly common site of Candida infection.

Exploration of a Potential Desirability of Outcome Ranking Endpoint for Complicated Intra-Abdominal Infections Using 9 Registrational Trials for Antibacterial Drugs.

BACKGROUND: Desirability of outcome ranking (DOOR) is a novel approach to clinical trial design that incorporates safety and efficacy assessments into an ordinal ranking system to evaluate overall outcomes of clinical trial participants. Here, we derived and applied a disease-specific DOOR endpoint to registrational trials for complicated intra-abdominal infection (cIAI). METHODS: Initially, we applied an a priori DOOR prototype to electronic patient-level data from 9 phase 3 noninferiority trials for cIAI submitted to the US Food and Drug Administration between 2005 and 2019. We derived a cIAI-specific DOOR endpoint based on clinically meaningful events that trial participants experienced. Next, we applied the cIAI-specific DOOR endpoint to the same datasets and, for each trial, estimated the probability that a participant assigned to the study treatment would have a more desirable DOOR or component outcome than if assigned to the comparator. RESULTS: Three key findings informed the cIAI-specific DOOR endpoint: (1) a significant proportion of participants underwent additional surgical procedures related to their baseline infection; (2) infectious complications of cIAI were diverse; and (3) participants with worse outcomes experienced more infectious complications, more serious adverse events, and underwent more procedures. DOOR distributions between treatment arms were similar in all trials. DOOR probability estimates ranged from 47.4% to 50.3% and were not significantly different. Component analyses depicted risk-benefit assessments of study treatment versus comparator. CONCLUSIONS: We designed and evaluated a potential DOOR endpoint for cIAI trials to further characterize overall clinical experiences of participants. Similar data-driven approaches can be utilized to create other infectious disease-specific DOOR endpoints.

Intra-abdominal infection after tumor surgery: tigecycline combined with ß-lactam antibiotics versus tigecycline alone.

BACKGROUNDS: Tigecycline has a broad spectrum of antimicrobial activity and has been approved for the treatment of complicated intra-abdominal infections. However, it is debatable whether tigecycline should be used alone or in combination. This study aimed to investigate whether tigecycline plus ß-lactam antibiotics (combination therapy [CT] group) are superior to tigecycline alone (monotherapy [MT] group) in non-critically ill intra-abdominal infection patients after tumor surgery. METHODS: This was a multicenter, retrospective cohort study. The primary outcome was mortality during the hospital stay. Secondary outcomes were clinical success rate, microbial eradication rate, relapse rate within one week, course of treatment, and adverse effects. Propensity score matching (PSM) was used to adjust the degree of infection before medication between the MT and CT groups. Univariate comparisons were performed using the chi-squared test for qualitative variables and Student's t-test or the Mann-Whitney U-test for continuous variables, as appropriate. Multivariate logistic regression analysis was performed to examine the relationship between antimicrobial treatments and mortality during hospitalization. The paired samples Wilcoxon test was used to compare the parameters before and after medication. RESULTS: In total, 291 patients were included in the final analysis: 128 in MT group and 163 in CT group. Mortality rate was 6.25% in the MT group and 6.13% in the CT group (P = 0.97). Multivariate logistic regression model showed that carbapenem-resistant organisms (OR: 4.35, 95% CI: 2.36 ~ 61.70) and age > 65 (OR: 1.32, 95% CI:1.19 ~ 3.01) were independent risk factors for death. CT group had a shorter defervescence time (P < 0.05), with less likelihood of relapse (P < 0.05) but had a more significant effect on activated partial thromboplastin and prothrombin time. CONCLUSIONS: Tigecycline plus ß-lactam wasn't superior to tigecycline monotherapy for the treatment of non-critically ill patients with intra-abdominal infection. But for advanced age patients with cancer, tigecycline combination therapy maybe a better choice in terms of mortality.

Use of 1,3-Beta-D-Glucan concentration in peritoneal fluid for the diagnosis of intra-abdominal Candidiasis in Critically-ill patients.

Intra-Abdominal Candidiasis (IAC) is frequent and associated with high mortality in intensive care unit (ICU) patients. Antifungal treatments may be overused due to a lack of diagnostic tools to rule out IAC. Serum 1,3-Beta-D-Glucan (BDG) concentrations are used to diagnose Candida infections, its concentration in peritoneal fluid (PF) may help to confirm or invalidate the diagnosis of IAC. We performed a non-interventional, prospective, multicenter study, at the Hospices Civils de Lyon, France, in seven ICU located in three different hospitals from December 2017 to June 2018. IAC was defined as the isolation of Candida in a sample collected from the intra-abdominal cavity under sterile conditions in patients displaying clinical evidence of intra-abdominal infection. Among the 113 included patients, 135 PF samples corresponding to 135 intra-abdominal infection episodes were collected and BDG concentrations were assessed. IAC accounted for 28 (20.7%) of the intra-abdominal infections. Antifungals were administered empirically to 70 (61.9%) patients; among them, 23 (32.9%) had an IAC. The median [IQR] BDG value was significantly higher in IAC (8100 [3000;15000] pg/mL) than in non-IAC samples (1961 [332;10650] pg/mL). BDG concentrations were higher in PF with Fecaloid aspect and in case of positive bacterial culture. For a BDG threshold of 125 pg/mL, the negative predictive value to assess IAC was 100%. In conclusion, low BDG PF concentrations could be used to rule out IAC. https://clinicaltrials.gov/ct2/show/NCT03469401.

Intra-Abdominal Candidiasis (IAC) is associated with a high mortality in Intensive Care Unit (ICU) patients. 1,3-Beta-D-Glucan (BDG), a component of Candida cell wall, was prospectively measured in peritoneal fluid from ICU patients Low peritoneal BDG concentrations may be used to rule out IAC.

Efficacy, safety, and tolerability of antimicrobial agents for complicated intra-abdominal infection: a systematic review and network meta-analysis.

BACKGROUND: Which antimicrobial agents provide the optimal efficacy, safety, and tolerability for the empirical treatment of complicated intra-abdominal infection (cIAI) remains unclear but is paramount in the context of evolving antimicrobial resistance. Therefore, updated meta-analyses on this issue are warranted. METHODS: We systematically searched four major electronic databases from their inception through October 2022. Randomized controlled trials examining antimicrobial agents for cIAI treatment were included. Two reviewers independently assessed the quality of included studies utilizing the Cochrane Collaboration's risk of bias tool as described in the updated version 1 of the Cochrane Collaboration Handbook and extracted data from all manuscripts according to a predetermined list of topics. All meta-analyses were conducted using R software. The primary outcome was clinical success rate in patients with cIAIs. RESULTS: Forty-five active-controlled trials with low to medium methodological quality and involving 14,267 adults with cIAIs were included in the network meta-analyses. The vast majority of patients with an acute physiology and chronic health evaluation II score < 10 had low risk of treatment failure or death. Twenty-one regimens were investigated. In the network meta-analyses, cefepime plus metronidazole was more effective than tigecycline and ceftolozane/tazobactam plus metronidazole (odds ratio [OR] = 1.96, 95% credibility interval [CrI] 1.05 ~ 3.79; OR = 3.09, 95% CrI 1.02 ~ 9.79, respectively). No statistically significant differences were found among antimicrobial agents regarding microbiological success rates. Cefepime plus metronidazole had lower risk of all-cause mortality than tigecycline (OR = 0.22, 95% CrI 0.05 ~ 0.85). Statistically significant trends were observed favoring cefotaxime plus metronidazole, which exhibited fewer discontinuations because of adverse events (AEs) when compared with eravacycline, meropenem and ceftolozane/tazobactam plus metronidazole (OR = 0.0, 95% CrI 0.0 ~ 0.8; OR = 0.0, 95% CrI 0.0 ~ 0.7; OR = 0.0, 95% CrI 0.0 ~ 0.64, respectively). Compared with tigecycline, eravacycline was associated with fewer discontinuations because of AEs (OR = 0.17, 95% CrI 0.03 ~ 0.81). Compared with meropenem, ceftazidime/avibactam plus metronidazole had a higher rate of discontinuation due to AEs (OR = 2.09, 95% CrI 1.0 ~ 4.41). In pairwise meta-analyses, compared with ceftriaxone plus metronidazole, ertapenem and moxifloxacin (one trial, OR = 1.93, 95% CI 1.06 ~ 3.50; one trial, OR = 4.24, 95% CI 1.18 ~ 15.28, respectively) were associated with significantly increased risks of serious AEs. Compared with imipenem/cilastatin, tigecycline (four trials, OR = 1.57, 95%CI 1.07 ~ 2.32) was associated with a significantly increased risk of serious AEs. According to the surface under the cumulative ranking curve, Cefepime plus metronidazole was more likely to be optimal among all treatments in terms of efficacy and safety, tigecycline was more likely to be worst regimen in terms of tolerability, and eravacycline was more likely to be best tolerated. CONCLUSION: This study suggests that cefepime plus metronidazole is optimal for empirical treatment of patients with cIAIs and that tigecycline should be prescribed cautiously considering the safety and tolerability concerns. However, it should be noted that data currently available on the effectiveness, safety, and tolerability of antimicrobial agents pertain mostly to lower-risk patients with cIAIs.