Long-Term Continuous Antimicrobial Resistance Surveillance Among Nosocomial Gram-Negative Bacilli in China from 2010 to 2018 (CMSS)

Multicenter study on clinical outcomes and poor prognostic factors in patients with Klebsiella pneumoniae bacteremia receiving cefoperazone/sulbactam treatment

BACKGROUND

Infections caused by Klebsiella pneumoniae are common and result in high mortality rates. In vitro studies demonstrated the potency of cefoperazone/sulbactam (CPZ/SUL) against Klebsiella pneumoniae. However, the clinical efficacy of CPZ/SUL for the treatment of K. pneumoniae bacteremia has not been studied.

OBJECTIVES

This study aimed to associate the clinical outcomes of patients with bacteremia with the minimal inhibitory concentrations (MICs) of CPZ/SUL against the causative K. pneumoniae isolates.

METHODS

This multicenter, retrospective study was conducted in Taiwan between July 2017 and April 2021. Patients with K. pneumoniae bacteremia treated with CPZ/SUL were enrolled in this study. CPZ/SUL MICs were determined using the agar dilution method. Data on the patients' clinical outcomes and characteristics were collected and analyzed.

RESULTS

In total, 201 patients were enrolled. Among the causative K. pneumoniae isolates, 180 (89.5%) were susceptible to CPZ/SUL. Most patients (n = 156, 77.6%) had favorable outcomes. The 30-day mortality rate was 11.9% (n = 24). Multivariate risk analyses showed that higher APACHE II score (Odds Ratio [OR], 1.14; Confidence Interval [CI], 1.07-1.21; p < 0.001), metastatic tumors (OR, 5.76; CI, 2.31-14.40; p < 0.001), and causative K. pneumoniae CPZ/SUL MICs > 16 µg/ml (OR, 4.30; CI, 1.50-12.27; p = 0.006) were independently associated with unfavorable outcomes.

CONCLUSION

Patients with K. pneumoniae bacteremia treated with CPZ/SUL at a ratio 1:1 had favorable outcomes when the CPZ/SUL MICs were ≤ 16 µg/ml. Patients with higher APACHE II scores and metastatic tumors had unfavorable outcomes.

Acinetobacter spp. bloodstream infection in hematological patients: a 10-year single-center study

PURPOSE

This study investigated the clinical and antimicrobial characteristics of Acinetobacter spp. bloodstream infection (BSI) in hematological patients. Risk factors for 30-day mortality and carbapenem-resistant Acinetobacter spp. (CRA) BSI acquisition were also identified.

METHODS

We reviewed forty hematological patients with Acinetobacter spp. BSI in a large Chinese blood disease hospital between 2013 and 2022. The remaining CRA isolates were subjected to whole-genome sequencing.

RESULTS

The 30-day mortality rate was high at 35%. Hematological patients with Acinetobacter spp. BSI often presented with severe conditions and co-infections at multiple sites. All strains were colistin-susceptible and 40.0% were CR. Multivariate analysis identified several risk factors associated with CRA BSI acquisition, including previous exposure to carbapenems within 30 days and CRA colonization. Very severe aplastic anaemia, tetracycline-resistant Acinetobacter spp. BSI, and unresolved neutropenia after infection were closely associated with 30-day mortality. Non-survivors often presented with higher median PCT and CRP levels and severe complications, such as intracranial infection, cardiac dysfunction, respiratory failure, and severe sepsis or septic shock. Our study also identified inappropriate empirical antibiotic therapy as an independent predictor of 30-day mortality (OR: 11.234, 95% CI: 1.261-20.086, P = 0.030). This study was the first to report A. oleivorans as a human pathogen, and to identify its unique oxacillinase, OXA-325.

CONCLUSION

An environment-originated non-pathogenic species can become pathogenic when the body's immunity is compromised. Our results also highlighted the importance of improving neutropenia after infection, treating severe organ dysfunction, and administering appropriate empirical antibiotic therapy to reduce mortality in this patient population.

Nebulized colistin as the adjunctive treatment for ventilator-associated pneumonia: A systematic review and meta-analysis

PURPOSE

Nebulized colistin (NC) is a potential therapy for ventilator-associated pneumonia (VAP); however, the clinical efficacy and safety of NC remain unclear. This study investigated whether NC is an effective therapy for patients with VAP.

MATERIALS AND METHODS

We performed a search in Web of Science, PubMed, Embase, and the Cochrane Library to retrieve randomized controlled trials (RCTs) and observational studies published at any time until February 6, 2023. The primary outcome was clinical response. Secondary outcomes included microbiological eradication, overall mortality, length of mechanical ventilation (MV), length of intensive care unit stay (ICU-LOS), nephrotoxicity, neurotoxicity, and bronchospasm.

RESULTS

Seven observational studies and three RCTs were included. Despite exhibiting a higher microbiological eradication rate (OR,2.21; 95%CI, 1.25-3.92) and the same nephrotoxicity risk (OR,0.86; 95%CI, 0.60-1.23), NC was not significantly different in clinical response (OR,1.39; 95%CI, 0.87-2.20), overall mortality (OR,0.74; 95%CI, 0.50-1.12), MV length (mean difference (MD),-2.5; 95%CI, -5.20-0.19), and the ICU-LOS (MD,-1.91; 95%CI, -6.66-2.84) than by the intravenous antibiotic. Besides, the risk of bronchospasm raised significantly (OR, 5.19; 95%CI, 1.05-25.52) among NC.

CONCLUSION

NC was associated with better microbiological outcomes but did not result in any remarkable changes in the prognosis of patients with VAP.

Correlation Between Cefoperazone/Sulbactam MIC Values and Clinical Outcomes of Escherichia coli Bacteremia

INTRODUCTION

The clinical efficiency of cefoperazone/sulbactam (CPZ/SUL) against Escherichia coli bacteremia was unknown. This study aimed to explore the relationship between CPZ/SUL MIC values and clinical outcomes in Escherichia coli bacteremia.

METHODS

A multicenter, retrospective, observational cohort study was conducted in Taiwan between January 2015 and December 2020. Patients treated with CPZ/SUL for E. coli bacteremia were enrolled in the analysis. The CPZ/SUL MICs were determined by using the agar dilution method. The primary outcome was 30-day mortality.

RESULTS

Among 247 isolates, 160 (64.8%) isolates were susceptible, 8 (3.2%) were intermediate, and 79 (32.0%) were resistant to cefoperazone. The activity of cefoperazone against cefoperazone-non-susceptible E. coli (n = 87) was restored upon combination with sulbactam, with susceptibility ranging from 0% to 97.7%. The 30-day mortality was 4.5% (11/247) and overall clinical success rate was 91.9% (227/247). Multivariate Cox proportional-hazards model revealed that heart failure [adjusted relative risk (ARR), 5.49; 95% confidence interval (CI) 1.31-23.02; p = 0.020], malignancy (ARR 7.50; 95% CI 2.02-27.80; p = 0.003), SOFA score (ARR 1.29; 95% CI 1.09-1.52; p = 0.003), and CPZ/SUL MIC ≥ 64 mg/L (ARR 11.31; 95% CI 1.34-95.52; p = 0.026) were independently associated with 30-day mortality. No statistically significant differences in 30-day mortality were found between groups with or without cefoperazone susceptibility (3.4% vs. 5.0%, p = 0.751, respectively).

CONCLUSIONS

Patients with E. coli bacteremia who were treated with CPZ/SUL had a favorable outcome when the MICs of the isolates were ≤ 16 mg/L and a high risk of mortality with MICs ≥ 64 mg/L.

Origin, Phylogeny, and Transmission of the Epidemic Clone ST208 of Carbapenem-Resistant Acinetobacter baumannii on a Global Scale

Carbapenem-resistant Acinetobacter baumannii (CRAB) is an opportunistic pathogen that has become a global threat. The dissemination of global clone 2 (GC2) CRAB has been well documented. Oxford sequence type (ST) 208 is one of the most prevalent lineages of A. baumannii GC2; however, its evolution and phylogeny are unclear. We collected 45 representative ST208 isolates from 14 cities in China between 1999 and 2018. Moreover, 411 ST208 genome sequences were downloaded from the GenBank database for comparison. The global ST208 phylogeny showed that ST208 might have originated from North America and subsequently evolved into two clades. Notably, the widespread OXA-23-producing ST208 A. baumannii was correlated with the transposon structure and dynamics of replicative transposition, and the Tn2009 tandem structure of five copies of blaOXA-23 and potential circular intermediate of Tn2009 were first detected. Furthermore, 15 Chinese ST208 isolates carried GR25 pABTJ1-like plasmids, which contained blaOXA-23 and have only been found in China in the last decade. In conclusion, our work suggests that replicative transposition contributes to the evolution and transmission of OXA-23-producing ST208 A. baumannii and highlights the new challenges posed by the epidemiological surveillance of globally distributed clonal groups via whole genome sequencing. IMPORTANCE ST208 as one of the most prevalent lineages of CRAB has caused several difficult-to-treat infections and outbreaks around the world. However, few studies have focused on evaluating the genetic background differences of ST208 A. baumannii isolated from very distant geographic regions. A comprehensive genomic analysis of 456 clinical strains of ST208 A. baumannii from a wide temporal and geographic range was performed in this study. Moreover, the mechanisms leading to the horizontal transfer of blaOXA-23 in ST208 A. baumannii are poorly understood. We first describe experimental evidence of the potential circular intermediate of Tn2009, and the Tn2009 tandem structure of five copies of blaOXA-23 was first detected. The interbacterial transfer of genetic elements carrying resistance to last-line antibiotic carbapenems highlights the essential need to enhance epidemiologic surveillance.

Derivation and Validation of a Predictive Scoring Model of Infections Due to Acinetobacter baumannii in Patients with Hospital Acquired Pneumonia by Gram-Negative Bacilli

Background

The prognosis of ABA-HAP patients is very poor. This study aimed to develop a scoring model to predict ABA-HAP in patients with GNB-HAP.

Methods

A single center retrospective cohort study was performed among patients with HAP caused by GNB in our hospital during January 2019 to June 2019 (the derivation cohort, DC). The variables were assessed on the day when qualified respiratory specimens were obtained. A prediction score was formulated by using independent risk factors obtained from logistic regression analysis. It was prospectively validated with a subsequent cohort of GNB-HAP patients admitted to our hospital during July 2019 to Dec 2019 (the validation cohort, VC).

Results

The final logistic regression model of DC included the following variables: transferred from other hospitals (3 points); blood purification (3 points); risk for aspiration (4 points); immunocompromised (3 points); pulmonary interstitial fibrosis (3 points); pleural effusion (1 points); heart failure (3 points); encephalitis (5 points); increased monocyte count (2 points); and increased neutrophils count (2 points). The AUROC of the scoring model was 0.845 (95% CI, 0.796 ~ 0.895) in DC and 0.807 (95% CI, 0.759 ~ 0.856) in VC. The scoring model clearly differentiated the low-risk patients (the score < 8 points), moderate-risk patients (8 ≤ the score < 12 points) and high-risk patients (the score ≥ 12 points), both in DC (P < 0.001) and in VC (P < 0.001).

Conclusion

This simple scoring model could predict ABA-HAP with high predictive value and help clinicians to choose appropriate empirical antibiotic therapy.

Global Prevalence and Molecular Epidemiology of mcr-Mediated Colistin Resistance in Escherichia coli Clinical Isolates: A Systematic Review

BACKGROUND AND AIM

The continuing rise in infections caused by multi-drug resistant (MDR) bacteria is one of the most serious public health issues in today's societies. Colistin is a last-resort antimicrobial medication used to treat infections caused by MDR gram-negative bacteria; therefore resistance to this antibiotic is extremely hazardous. The current study aimed to evaluate the global prevalence and distribution of colistin resistance genes among human clinical isolates of Escherichia coli (E. coli) as a systematic review.

METHODS

PubMed, Embase, and Web of Science databases were systematically searched. For further evaluation, all original English-language articles that demonstrated colistin resistance in E. coli clinical isolates published between 2000 and 2020 were examined.

RESULTS

Out of 4857 initial articles, after various stages of review and evaluation, 190 related articles were selected. More than 79 % of the publications selected in this research were published from 2014 to 2020. In Asia, Europe, America, Africa, and Oceania, the prevalence of mobilized colistin resistance (mcr) producing colistin-resistant E. coli was 66.72%, 25.48%, 5.19%, 2.27%, and 0.32 %, respectively.

CONCLUSION

The recent widespread spreading of E. coli strains harboring mcr conferring colistin resistance, especially in Asia and Europe, is concerning and needs more attention.

The Occurrence of Klebsiella pneumoniae in Drainage Fluid After Pancreaticoduodenectomy: Risk Factors and Clinical Impacts

To investigate the risk factors and clinical impacts of the occurrence of Klebsiella pneumoniae isolated from drainage fluid in patients undergoing pancreaticoduodenectomy (PD). Clinicopathological data of all patients who underwent PD from January 2018 to March 2021 were analyzed retrospectively. The univariate and multivariate analyses were performed to identify independent risk factors for the occurrence of K. pneumoniae in drainage fluid and its clinical impacts on postoperative complications. Of the included 284 patients, 49 (17.2%) patients isolated K. pneumoniae in drain samples after PD. Preoperative biliary drainage (OR = 1.962, p = 0.037) independently predicted the contamination of K. pneumoniae in drain samples after PD. The rate of clinically relevant postoperative pancreatic fistula (CR-POPF), major complications (Clavien–Dindo Grade ≥ III), post-pancreatectomy hemorrhage (PPH), organ/space surgical site infection (SSI), and biliary leakage (BL) were significantly higher in K. pneumoniae positive group both in the univariate and multivariate analyses. Preventive measures and treatments for combating K. pneumoniae contamination may be beneficial to the perioperative outcomes of patients after PD.

Optimal Empiric Polymyxin B Treatment of Patients Infected with Gram-Negative Organisms Detected Using a Blood Antimicrobial Surveillance Network in China

Background

Few pharmacodynamics studies to date have evaluated the efficacy and safety of polymyxin B (PMB) in treating patients with bloodstream infections (BSIs) in China.

Methods

Patients with BSIs were identified using an antimicrobial surveillance network, and their pathogens were isolated. Patients were treated with a loading dose of PMB followed by either a weight-based or weight-independent maintenance dose. Monte Carlo simulation was utilized to calculate the probability of target attainment (PTA) and cumulative fraction of response (CFR) against Gram-negative organisms in patients with normal or decreased renal function.

Results

A total of 10,066 Gram-negative organisms, including 5500 Escherichia coli (Eco), 2519 Klebsiella pneumoniae (Kpn), 501 Acinetobacter baumannii (Aba), were isolated from patients with BSIs. Although these strains were highly resistant to carbapenem, they remained susceptible to PMB. Among patients with renal impairment (mean CrCL, 42 mL/min), a PMB 2.5 mg/kg loading dose followed by a maintenance dose of 60 mg q12h reached ≥90% PTA against isolates with an MIC of 2 mg/L, with a low risk of toxicity. Among patients with normal renal function (mean CrCL, 123 mL/min), all simulated regimens showed PTAs of 25–80%. A weight-based loading dose followed by either a weight-based or weight-independent maintenance dose showed a promising CFR, especially in patients with renal impairment, with CFRs ≥90% against carbapenem-resistant Eco, Kpn, and Aba. Simulated regimens showed a disappointing CFR (<80%) against carbapenem-resistant Pae in patients with normal renal function. Based on the optimal balance of efficacy and toxicity, a fixed maintenance dose of 60 mg q12h among patients with renal impairment yielded a CFR similar to regimens based on total body weight and was associated with a probability of toxicity (12.5%) significantly lower than that of simulations based on total body weight. Among patients with normal renal function, a weight-based maintenance dose of 1.25 mg/kg q12h achieved a higher CFR than a fixed maintenance dose, without significantly increasing toxicity.

Conclusion

A 2.5 mg/kg loading dose of PMB is optimal, regardless of renal function. A fixed maintenance dose of 60 mg q12h is recommended for empirical treatment of patients with renal impairment infected with Eco, Kpn, and Aba, whereas a weight-based maintenance dose of 1.25 mg/kg is recommended for patients with normal renal function.

Clinical and microbiological characteristics of nosocomial, healthcare-associated, and community-acquired Klebsiella pneumoniae infections in Guangzhou, China

BACKGROUND

Klebsiella pneumoniae (K. pneumoniae) is a common pathogen associated with hospital and community-onset infections. This study aimed to compare the clinical and microbiological characteristics of nosocomial, healthcare-associated (HCA), and community-acquired (CA) K. pneumoniae infections.

METHODS

Clinical data were extracted from electronic medical records and analyzed retrospectively. Antimicrobial susceptibility and extended-spectrum beta-lactamase (ESBL) production were determined for all identified strains. Carbapenemase and ESBL genes were amplified by PCR. Genotyping of carbapenem-resistant K. pneumoniae (CRKP) and ESBL-producing strains was performed by pulsed-field gel electrophoresis (PFGE).

RESULTS

Of 379 K. pneumoniae infections, 98 (25.9%) were nosocomial, 195 (51.5%) were healthcare-associated, and 86 (22.6%) were community-acquired. Hematological malignancy (OR = 4.467), and hypertension (OR = 2.08) and cerebral vascular disease (OR = 2.486) were associated with nosocomial and HCA infections respectively, when compared to CA infections. Overall, the incidence of antimicrobial resistance for the majority of agents tested was similar between nosocomial and HCA infections (P > 0.05) and both groups had a higher incidence than CA infections (P < 0.05). Moreover, 95.1% (78/82) of CRKP strains were isolated from the nosocomial and HCA groups. The blaKPC was the most prevalent carbapenemase gene among CRKP strains (80.5%, 66/82). ESBL-producing strains were prevalent among nosocomial (40.8%), HCA (35.9%) and CA groups (24.4%). The blaCTX-M-9-group and blaCTX-M-1-group genes were predominant in nosocomial (65.0%) and CA strains (66.7%), respectively. PFGE results showed ESBL-producing and CRKP strains were genetically diverse. Identical PFGE profiles were observed among HCA and nosocomial strains.

CONCLUSIONS

Nosocomial and HCA K. pneumoniae infections presented similar clinical features and antimicrobial resistance, and both two types of infections were different to CA infections. CRKP and ESBL-producing strains were disseminated mainly in HCA and nosocomial groups, and showed a clonal diversity. The cross transmission of CRKP was existed among HCA and nosocomial patients. This finding suggests that similar empirical therapy should be considered for patients with nosocomial and HCA K. pneumoniae infections and bacterial resistance surveillance of these infections is necessary.