A multicenter epidemiology study on the risk factors and clinical outcomes of nosocomial intra-abdominal infections in China: results from the Chinese Antimicrobial Resistance Surveillance of Nosocomial Infections (CARES) 2007-2016

Primary mesenteric abscess caused by Klebsiella pneumoniae: A case report

RATIONALE

Mesenteric abscess, a rare abdominal infection, is regularly mostly secondary to inflammatory bowel disease, diverticula of the small intestine, or tuberculosis. Primary mesenteric abscesses are extremely rare. If not diagnosed and treated in a timely manner, it may lead to serious consequences; computerized tomography is highly beneficial for the diagnosis of this disease; timely surgical intervention, judicious use of antibiotics, and adequate nutritional support are crucial in the management of this disease.

PATIENT CONCERNS

A 59-year-old male patient from China was admitted to hospital for intermittent abdominal pain accompanied by poor appetite for 10 days. One week before admission, the patient had been infected with corona virus disease 2019. Past history includes type 2 diabetes and post-operative gastric cancer.

DIAGNOSIS

The emergency abdominal computerized tomography examination results of the patient suggested that the mesentery was cloudy with a large amount of effusion and visible bubble. Mesentery abscess was considered, but duodenal perforation could not be excluded.

INTERVENTIONS

We adopted exploratory laparotomy to further clarify the diagnosis. Intraoperatically, after fully exposing the duodenum, we found extensive abscess formation in the mesentery, but no duodenal perforation. After operation, the patient developed duodenal leakage and was treated with gastric tube and jejunal nutrition tube.

OUTCOMES

Postoperatively, due to poor general condition, the patient was transferred to intensive care unit; after anti-infective treatment, the condition improved on the 5th postoperative day, and duodenal leakage appeared on the 9th postoperative day, and conservative treatment was ineffective, and the patient eventually died.

LESSONS

Primary mesenteric abscess is a local tissue infectious disease. Whereas we should consider the physical basic condition of the patient during therapeutic process. We believe adequate postoperative drainage, rational use of antibiotics based on bacterial culture, early ambulation after surgery, and adequate nutritional support might be key points for successful therapy.

Application of metagenomic sequencing of drainage fluid in rapid and accurate diagnosis of postoperative intra-abdominal infection: a diagnostic study

BACKGROUND

Postoperative intra-abdominal infection (PIAI) is one of the most serious complications of abdominal surgery, increasing the risk of postoperative morbidity and mortality and prolonging hospital stay. Rapid diagnosis of PIAI is of great clinical value. Unfortunately, the current diagnostic methods of PIAI are not fast and accurate enough.

METHODS

The authors performed an exploratory study to establish a rapid and accurate diagnostic method of PIAI. The authors explored the turnaround time and accuracy of metagenomic next-generation sequencing (mNGS) in diagnosing PIAI. Patients who underwent elective abdominal surgery and routine abdominal drainage with suspected PIAI were enroled in the study. The fresh midstream abdominal drainage fluid was collected for mNGS and culturing.

RESULTS

The authors found that the median sample-to-answer turnaround time of mNGS was dramatically decreased than that of culture-based methods (<24 h vs. 59.5-111 h). The detection coverage of mNGS was much broader than culture-based methods. The authors found 26 species from 15 genera could only be detected by mNGS. The accuracy of mNGS was not inferior to culture-based methods in the 8 most common pathogens detected from abdominal drainage fluid (sensitivity ranged from 75 to 100%, specificity ranged from 83.3 to 100%, and kappa values were higher than 0.5). Moreover, the composition of the microbial spectrum established by mNGS varied between upper and lower gastrointestinal surgery, enhancing the understanding of PIAI pathogenesis.

CONCLUSION

This study preliminarily revealed the clinical value of mNGS in the rapid diagnosis of PIAI and provided a rationale for further research.

Roquin-1 resolves sepsis-associated acute liver injury by regulating inflammatory profiles via miRNA cargo in extracellular vesicles

Sepsis-associated acute liver injury (SALI) is an independent risk for sepsis-induced death orchestrated by innate and adaptive immune responses. Here, we found that Roquin-1 was decreased during SALI and expressed mainly in monocyte-derived macrophages. Meanwhile, Roquin-1 was correlated with the inflammatory profiles in humans and mice. Mechanically, Roquin-1 in macrophages promoted Ago2-K258-ubiquitination and inhibited Ago2-S387/S828-phosphorylation. Ago2-S387-phosphorylation inhibited Ago2-miRNA's complex location in multivesicular bodies and sorting in macrophages-derived extracellular vesicles (MDEVs), while Ago2-S828-phosphorylation modulated the binding between Ago2 and miRNAs by special miRNAs-motifs. Then, the anti-inflammatory miRNAs in MDEVs decreased TSC22D2 expression directly, upregulated Tregs-differentiation via TSC22D2-STAT3 signaling, and inhibited M1-macrophage-polarization by TSC22D2-AMPKα-mTOR pathway. Furthermore, WT MDEVs in mice alleviated SALI by increasing Tregs ratio and decreasing M1-macrophage frequency synchronously. Our study showed that Roquin-1 in macrophages increased Tregs-differentiation and decreased M1-macrophage-polarization simultaneously via miRNA in MDEVs, suggesting Roquin-1 can be used as a potential tool for SALI treatment and MDEVs engineering.

An Economic Evaluation Estimating the Clinical and Economic Burden of Increased Vancomycin-Resistant Enterococcus faecium Infection Incidence in Japan

INTRODUCTION

While incidence rates of vancomycin-resistant Enterococcus faecium have remained comparatively low in Japan, there have been increasing reports of more vancomycin-resistant Enterococcus (VRE) outbreaks, requiring costly measures to contain. Increased incidence of VRE in Japan may lead to more frequent and harder to contain outbreaks with current control measures, causing a significant burden to the healthcare system in Japan. This study aimed to demonstrate the clinical and economic burden of vancomycin-resistant E. faecium infections to the Japanese healthcare system and the impact of increasing rates of vancomycin resistance.

METHODS

A de novo deterministic analytic model was developed to assess the health economic outcomes of treating hospital-acquired VRE infections; patients are treated according to a two-line treatment strategy, dependent on their resistance status. The model considers hospitalisation costs and the additional cost of infection control. Scenarios investigated the current burden of VRE infections and the additional burden of increased incidence of VRE. Outcomes were assessed over a 1-year and 10-year time horizon from a healthcare payer's perspective in a Japanese setting. Quality-adjusted life years (QALYs) were valued with a willingness-to-pay threshold of ¥5,000,000 ($38,023), and costs and benefits were discounted at a rate of 2%.

RESULTS

Current VRE incidence levels in enterococcal infections in Japan equates to ¥130,209,933,636 ($996,204,669) in associated costs and a loss of 185,361 life years (LYs) and 165,934 QALYs over 10 years. A three-fold increase (1.83%) is associated with an additional ¥4,745,059,504 ($36,084,651) in total costs on top of the current cost burden as well as an additional loss of 683 LYs over a lifetime, corresponding to 616 QALYs lost.

CONCLUSION

Despite low incidence rates, VRE infections already represent a substantial economic burden to the Japanese healthcare system. The substantial increase in costs associated with a higher incidence of VRE infections could result in a significant economic challenge for Japan.

Sepsis Team Organizational Model to Decrease Mortality for Intra-Abdominal Infections: Is Antibiotic Stewardship Enough?

Introduction. Sepsis is an overwhelming reaction to infection with significant morbidity, requiring urgent interventions in order to improve outcomes. The 2016 Sepsis-3 guidelines modified the previous definitions of sepsis and septic shock, and proposed some specific diagnostic and therapeutic measures to define the use of fluid resuscitation and antibiotics. However, some open issues still exist. Methods. A literature research was performed on PubMed and Cochrane using the terms "sepsis" AND "intra-abdominal infections" AND ("antibiotic therapy" OR "antibiotic treatment"). The inclusion criteria were management of intra-abdominal infection (IAI) and effects of antibiotic stewardships programs (ASP) on the outcome of the patients. Discussion. Sepsis-3 definitions represent an added value in the understanding of sepsis mechanisms and in the management of the disease. However, some questions are still open, such as the need for an early identification of sepsis. Sepsis management in the context of IAI is particularly challenging and a prompt diagnosis is essential in order to perform a quick treatment (source control and antibiotic treatment). Antibiotic empirical therapy should be based on the kind of infection (community or hospital acquired), local resistances, and patient's characteristic and comorbidities, and should be adjusted or de-escalated as soon as microbiological information is available. Antibiotic Stewardship Programs (ASP) have demonstrated to improve antimicrobial utilization with reduction of infections, emergence of multi-drug resistant bacteria, and costs. Surgeons should not be alone in the management of IAI but ideally inserted in a sepsis team together with anaesthesiologists, medical physicians, pharmacists, and infectious diseases specialists, meeting periodically to reassess the response to the treatment. Conclusion. The cornerstones of sepsis management are accurate diagnosis, early resuscitation, effective source control, and timely initiation of appropriate antimicrobial therapy. Current evidence shows that optimizing antibiotic use across surgical specialities is imperative to improve outcomes. Ideally every hospital and every emergency surgery department should aim to provide a sepsis team in order to manage IAI.

Antimicrobial Resistance Among Pathogens Causing Bloodstream Infections: A Multicenter Surveillance Report Over 20 Years (1998–2017)

Purpose

Bloodstream infections (BSIs) are a common consequence of infectious diseases and cause high morbidity and mortality. Appropriate antibiotic use is critical for patients’ treatment and prognosis. Long-term monitoring and analysis of antimicrobial resistance are important in guiding physicians to choose appropriate antibiotics and understand the changes in antimicrobial resistance and infection control. Here, we report a retrospective study on the trends of antimicrobial resistance in the common BSI-associated pathogens.

Methods

The identification of strains and antimicrobial susceptibility tests were performed in each anticipating hospital independently. Data from the Hubei Province Antimicrobial Resistance Surveillance System (HBARSS) from 1998 to 2017 were retrospectively analyzed using WHONET 5.6 software.

Results

Data from HBARSS (1998–2017) revealed that 40,518 Gram-positive bacteria and 26,568 Gram-negative bacteria caused BSIs, the most common of which were Staphylococcus aureus and Escherichia coli. Salmonella typhi was a predominant BSI-associated pathogen in 1998–2003. Antimicrobial susceptibility data showed that the resistance rates of E. coli and Klebsiella pneumoniae to cefotaxime were significantly higher than those to ceftazidime. The proportion of strains of special antimicrobial resistance phenotypes including difficult-to-treat resistance (DTR), carbapenem-resistant (CR), extended-spectrum cephalosporin resistant (ECR) and fluoroquinolone resistant (FQR) in E. coli was 0.18%, 0.26%, 13.95%, 22.78% while in K. pneumoniae was 11.95%, 14.00%, 31.91% and 11.40%, respectively. In 2013–2017, K. pneumoniae showed resistance levels reaching 15.8% and 17.5% to imipenem and meropenem, respectively, and Acinetobacter baumannii showed high resistance rates ranging from 60 to 80% to common antibiotics. The detection rate of Salmonella typhi resistance to third-generation cephalosporins and fluoroquinolones was less than 5%. Control of methicillin-resistant Staphylococcus aureus (MRSA) remains a major challenge, and in 2009–2017, the MRSA detection rate was 40–50%.

Conclusion

Prevalence of CR K. pneumoniae has increased significantly in recent years. Resistance rates of A. baumannii to common antimicrobial agents have increased exponentially, reaching high levels. MRSA remains a challenge to control. For K. pneumoniae, DTR, CR, ECR and FQR were antimicrobial resistance phenotypes that could not be ignored while for E. coli DTR and CR were rare antimicrobial resistance phenotypes. CR K. pneumoniae, A. baumannii and MRSA present major challenges for controlling BSIs.

Clinical Characteristics and Early Prognostic Factors of Severe Acute Pancreatitis

Objectives: To analyze the clinical characteristics of severe acute pancreatitis (SAP) patients retrospectively and explore the effective factors in death from severe acute pancreatitis (SAP). Methods: The required data were collected from 234 SAP patients admitted to our department from January 2013 to December 2020 and then analyzed retrospectively. According to the prognosis, all patients were admitted within 72 hours of onset and were assigned to the death and survival groups. The participants’ clinical and demographic information, laboratory indices when patients were brought to the intensive care unit (ICU), and organ failure were analyzed using univariate and logistic multivariate regression. The logistic regression (LR) model was developed and evaluated by the receiver operating characteristic (ROC) curve. Results: In this study, the total mortality rate was 11.96% (95% CI, 8.1 - 16.8%). The univariate analysis revealed a significant relationship between SAP-related death with age, ICU admission within 24 hours of onset, APACHE II score, serum amylase, serum albumin, PaO2, acute respiratory distress syndrome (ARDS), renal insufficiency, and other diseases (P < 0.05). The multivariate logistic regression analysis further demonstrated that ICU admission within 24 hours of onset, serum albumin, ARDS, and renal insufficiency were independent early prognostic factors of SAP (P < 0.05). LR model: Y = -0.108 - 1.852 × ICU admission within 24 hours of onset -0.102 × serum albumin + 1.790 × ARDS + 1.150 × renal insufficiency. The area under the curve (AUC) and 95% CI of the LR model were 0.864 (0.811 - 0.917) with the optimal threshold of 2.246. The sensitivity and specificity were 0.709 and 0.929, respectively. Conclusions: The SAP patients or acute pancreatitis (AP) patients at risk of developing SAP should be transferred to ICU at the earliest convenience. Moreover, hypoalbuminemia, ARDS, and renal insufficiency indicate poor prognosis.

Clinical Profile, Prognostic Factors, and Outcome Prediction in Hospitalized Patients With Bloodstream Infection: Results From a 10-Year Prospective Multicenter Study

Background: Bloodstream infection (BSI) is one of the most common serious bacterial infections worldwide and also a major contributor to in-hospital mortality. Determining the predictors of mortality is crucial for prevention and improving clinical prognosis in patients with nosocomial BSI. Methods: A nationwide prospective cohort study was conducted from 2007 until 2016 in 16 teaching hospitals across China. Microbiological results, clinical information, and patient outcomes were collected to investigate the pathogenic spectrum and mortality rate in patients with BSI and identify outcome predictors using multivariate regression, prediction model, and Kaplan-Meier analysis. Results: No significant change was observed in the causative pathogen distribution during the 10-year period and the overall in-hospital mortality was 12.83% (480/3,741). An increased trend was found in the mortality of patients infected with Pseudomonas aeruginosa or Acinetobacter baumannii, while a decreased mortality rate was noted in Staphylococcus aureus-related BSI. In multivariable-adjusted models, higher mortality rate was significantly associated with older age, cancer, sepsis diagnosis, ICU admission, and prolonged hospital stay prior to BSI onset, which were also determined using machine learning-based predictive model achieved by random forest algorithm with a satisfactory performance in outcome prediction. Conclusions: Our study described the clinical and microbiological characteristics and mortality predictive factors in patients with BSI. These informative predictors would inform clinical practice to adopt effective therapeutic strategies to improve patient outcomes.

Impact of environmental cleaning on the colonization and infection rates of multidrug-resistant Acinetobacter baumannii in patients within the intensive care unit in a tertiary hospital

Objective

To continuously evaluate the effect of environmental cleaning and hand hygiene compliance on the colonization and infection rates of multidrug-resistant Acinetobacter baumannii (MDR-AB) in the patients within an intensive care unit (ICU).

Methods

Environmental cleaning on the high-touch clinical surfaces (HTCS) within a comprehensive ICU was evaluated through monitoring fluorescent marks when the overall compliance with hand hygiene during 2013–2014 was monitored. Meanwhile, samples from the HTCS and inpatients were collected and sent for bacterial culture and identification. The drug susceptibility testing was further implemented to monitor the prevalence of MDR-AB. The genetic relatedness of MDR-AB collected either from the HTCS or inpatients was analyzed by pulsed field gel electrophoresis (PFGE) when an outbreak was doubted.

Results

The overall compliance with hand hygiene remained relatively stable during 2013–2014. Under this circumstance, the clearance rate of fluorescence marks on the environmental surfaces within ICUs significantly increased from 21.9 to 85.7%, and accordingly the colonization and infection rates of MDR-AB decreased from 16.5 to 6.6‰ and from 7.4 to 2.8‰, respectively, from the beginning to the end of 2013. However, during 2014, because of frequent change and movement of environmental services staff, the clearance rate of fluorescence marks decreased below 50.0%, and the overall colonization and infection rates of MDR-AB correspondingly increased from 9.1 to 11.1‰ and from 1.5 to 3.9‰, respectively. PFGE displayed a high genetic relatedness between the MDR-AB strains analyzed, indicating a dissemination of MDR-AB during the surveillance period.

Conclusion

For the easily disseminated MDR-AB within ICUs, the clearance rate of fluorescence labeling on HTCS is negatively correlated with the hospital infection rate of MDR-AB. Such an invisible fluorescence labelling is an effective and convenient method to continuously monitor cleanness of medical environment within hospitals.

Prospective multi-center evaluation on risk factors, clinical characteristics and outcomes due to carbapenem resistance in Acinetobacter baumannii complex bacteraemia: experience from the Chinese Antimicrobial Resistance Surveillance of Nosocomial Infections (CARES) Network

Introduction. Increasing evidence demonstrates unfavourable outcomes in bloodstream infections (BSI) due to the carbapenem-resistant Acinetobacter baumannii complex (CRAB).Aim. To investigate the differences in risk factors, clinical characteristics and outcomes in patients with A. baumannii complex BSI stratified by carbapenem resistance, a prospective multi-center study was conducted.Methodology. Information was collected in a predefined form. A total of 317 cases was included for comparison between CRAB BSI vs. carbapenem-susceptible A. baumannii complex (CSAB) BSI. Among these cases, 229 cases were defined as CRAB BSI and 88 cases as CSAB BSI.Results. Univariable analysis showed that male gender, underlying neurologic disease, prior carbapenems exposure, intensive care unit (ICU) stay, presence of central venous catheter, endotracheal intubation, tracheotomy, Foley catheter, nasogastric intubation, lower respiratory tract infections and catheter-related infections were more prevalent in CRAB BSI. Only male gender, prior carbapenems exposure and presence of endotracheal intubation persisted as independent risk factors for acquiring CRAB BSI. Patients with CRAB BSI displayed unfavourable outcomes characterized by failure of pathogen clearance, continuous fever, disease aggravation and higher incidence of 30-day all-cause mortality. Multivariate analysis demonstrated carbapenem resistance as an independent risk factor for 30-day all-cause mortality.Conclusion. Our findings reveal the epidemiological differences between CRAB BSI and CSAB BSI in a Chinese cohort. Our data suggest that carbapenem resistance has a significant impact on mortality for patients with A. baumannii complex BSI, further strengthening the importance of active prevention and control strategies for the spread of CRAB in Chinese hospitals.

Effectiveness of intraoperative peritoneal lavage (IOPL) with saline in patient with intra-abdominal infections: a systematic review and meta-analysis protocol

INTRODUCTION

Intra-abdominal infections (IAIs) are common surgical emergencies and cause a significant worldwide burden per year. Since the concept of intraoperative peritoneal lavage (IOPL) was proposed in 1905, it has been widely used in the surgery practice. However, the effectiveness of IOPL in patients with IAIs has always been controversial. Our objective is to identify whether it is beneficial to flush the abdominal cavity with saline in IAIs surgery through a comprehensive systematic review and meta-analysis.

METHODS AND ANALYSIS

This protocol is reported in line with the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols. Electronic databases (including the Cochrane library, MEDLINE, EMBASE, Web of Science, etc) and clinical trial registry platforms will be searched from inception to 8 September 2019. Randomised controlled trials, quasi-randomised clinical trials and cohort studies comparing IOPL and suction alone in IAIs will be included. The primary outcomes are mortality and abscess rate. Two independent reviewers will screen literature, collect data and assess risk of bias of included studies. Discussion or a third reviewer will be referred for any disagreements. The Grading of Recommendations Assessment, Development and Evaluation approach will be used to assess the quality of the evidence. We will perform meta-analysis using random-effects model. Subgroup analysis, sensitivity analysis and publication bias will be conducted if data are enough.

ETHICS AND DISSEMINATION

Ethical approval is not required for this systematic review and meta-analysis protocol. Results of this study will be published in a peer-reviewed journal, presented at relevant conferences and disseminated to local and international policy makers.

PROSPERO REGISTRATION NUMBER

CRD42019145109.

Systematic Review and Meta-Analysis of the Efficacy of Appropriate Empiric Anti-Enterococcal Therapy for Intra-Abdominal Infection

Background: Delayed treatment of seriously infected patients results in increased mortality. However, antimicrobial therapy for the initial 24 to 48 hours is mostly empirically provided, without evidence regarding the causative pathogen. Whether empiric anti-enterococcal therapy should be administered to treat intra-abdominal infection (IAI) before obtaining culture results remains unknown. We performed a meta-analysis to explore the effects of empiric enterococci covered antibiotic therapy in IAI and the risk factors for enterococcal infection in IAI. Methods: We searched multiple databases systematically and included 23 randomized controlled trials (RCTs) and 13 observational studies. The quality of included studies was assessed, and the reporting bias was evaluated. Meta-analysis was performed using random effects or fixed effects models according to the heterogeneity. The risk ratio (RR), odds ratio (OR), and 95% confidence interval (CI) were calculated. Results: Enterococci-covered antibiotic regimens provided no improvement in treatment success compared with control regimens (RR, 0.99; 95% CI, 0.97-1.00; p = 0.15), with similar mortality and adverse effects in both arms. Basic characteristic analysis revealed that most of the enrolled patients with IAI in RCTs were young, lower risk community-acquired intra-abdominal infection (CA-IAI) patients with a relatively low APACHE II score. Interestingly, risk factor screening revealed that malignancy, corticosteroid use, operation, any antibiotic treatment, admission to intensive care unit (ICU), and indwelling urinary catheter could predispose the patients with IAI to a substantially higher risk of enterococcal infection. "Hospital acquired" itself was a risk factor (OR, 2.81; 95% CI, 2.34-3.39; p < 0.001). Conclusion: It is unnecessary to use additional agents empirically to specifically provide anti-enterococcal coverage for the management of CA-IAI in lower risk patients without evidence of causative pathogen, and risk factors can increase the risk of enterococcal infection. Thus, there is a rationale for providing empiric anti-enterococcal coverage for severely ill patients with CA-IAI with high risk factors and patients with hospital-acquired intra-abdominal infection (HA-IAI).

Rapid Emergence of Multidrug-Resistance among Gram Negative Isolates at a Tertiary Pediatric and Maternity Hospital in Ulaanbaatar, Mongolia

Introduction:

Information on microbiological and susceptibility profiles of clinical isolates in Mongolia is scarce, hampering infection control and clinical care.

Methods:

Species and resistance profiles of 6334 clinical gram negative isolates, collected at Mongolia's National Center for Maternal and Child Health between 2014 and 2017 were analyzed.

Results:

Annual proportion of multidrug-resistance among E. coli and Enterobacter isolates increased from 2.8% to 16.6% and 3.5% to 22.6% respectively; Klebsiella isolates exhibiting susceptibilities suggestive of extended spectrum beta-lactamase (ESBL) production from 73% to 94%. By 2017, 60.6% of Klebsiella isolates were multidrug-resistant, most originated from intensive care wards. Enterobacteriaceae exhibiting susceptibility patterns suggestive of ESBL production and multidrug-resistant organisms were common and their incidence increased rapidly.

Conclusion:

These findings will serve to build strategies to strengthen microbiological surveillance, diagnostics and infection control; and to develop empiric therapy and stewardship recommendations for Mongolia's largest Children's and Maternity hospital.

Biofilm Formation and Detection of Fluoroquinolone- and Carbapenem-Resistant Genes in Multidrug-Resistant Acinetobacter baumannii

Acinetobacter baumannii is an important opportunistic pathogen that shows resistance to cephalosporins, penicillins, carbapenems, fluoroquinolones, and aminoglycosides, the multiresistance being associated with its ability to form biofilms in clinical environments. The aim of this study was to determine biofilm formation and its potential association with genes involved in antibiotic resistance mechanisms of A. baumannii isolates of different clinical specimens. We demonstrated 100% of the A. baumannii isolates examined to be multidrug resistant (MDR), presenting a 73.3% susceptibility to cefepime and a 53.3% susceptibility to ciprofloxacin. All A. baumannii isolates were positive for bla_OXA-51, 33.3% being positive for bla_OXA-23 and ISAba1, and 73.3% being positive for gyrA. We found 86.6% of A. baumannii strains to be low-grade biofilm formers and 13.3% to be biofilm negative; culturing on Congo red agar (CRA) plates revealed that 73.3% of the A. baumannii isolates to be biofilm producers, while 26.6% were not. These properties, combined with the role of A. baumannii as a nosocomial pathogen, increase the probability of A. baumannii causing nosocomial infections and outbreaks as a complication during therapeutic treatments and emphasize the need to control A. baumannii biofilms in hospital environments.

Prophylactic and therapeutic protection of human IgG purified from sera containing anti-exotoxin A titers against pneumonia caused by Pseudomonas aeruginosa

Antibodies are effective alternative tools to combat infections caused by Pseudomonas aeruginosa (PA), especially multi-drug-resistant PA. Thus, to solve the urgent need for an anti-PA antibody drug, we hypothesized that anti-PA intravenous immunoglobulins could be a practical attempt. Exotoxin A (ETA) is one of the most important factors for PA infection and is also a critical target for the development of immune interventions. In this study, a total of 320 sera were collected from healthy volunteers. The concentration of ETA-specific antibodies was determined by a Luminex-based assay and then purified by affinity chromatography. The purified IgGs were able to neutralize the cytotoxicity of ETA in vitro. We showed they had a prophylactic and therapeutic protective effect in PA pneumonia and ETA toxemia models. In addition, administration of nonspecific IgGs also provided partial protection. Collectively, our results provide additional evidence for IVIG-based treatment of infections caused by multi-drug-resistant PA and suggest that patients at high risk of PA pneumonia could be prophylactically treated with anti-ETA IgGs or even with nonspecific IgGs.