Epidemiology of and risk factors for infection with extended-spectrum β-lactamase-producing carbapenem-resistant Enterobacteriaceae: results of a double case-control study

Molecular Screening of Carbapenem-Resistant K. pneumoniae (CRKP) Clinical Isolates for Concomitant Occurrence of Beta-Lactam Genes (CTX-M, TEM, and SHV) in the Kingdom of Bahrain

The emergence of extended-spectrum β-lactamase-producing Klebsiella pneumoniae, including CRKP infections, has resulted in significant morbidity and mortality worldwide. We aimed to explore the presence of bla genes (CTX-M, TEM, and SHV) in CRKP isolates. A total of 24 CRKP isolates were randomly selected from the Salmaniya Medical Complex Microbiology Laboratory. These isolates, which were positive for carbapenemases, were further explored for CTX-M, TEM, and SHV genes using PCR. All the CTX-M PCR amplicons were sent for sequencing. To determine genetic relatedness, molecular typing by ERIC-PCR was performed. The bla gene testing demonstrated that a significant proportion of these isolates harbored SHV, CTX-M, and TEM genes (100%, 91.6%, and 45.8%), respectively. Bioinformatic analyses confirmed CTX-M-15 in these isolates. ERIC-PCR analysis showed three clusters demonstrating genetic relatedness. The study findings reveal the concomitant carriage of the SHV and CTX-M-15 and a comparatively lower carriage of TEM genes in CRKP isolates. Our findings highlight the significance of routinely reporting the presence of antibiotic resistance genes along with regular antibiotic sensitivity reports, as this will aid clinicians in prescribing appropriate antibiotics.

The impact of concurrent bacterial lung infection on immunotherapy in patients with non-small cell lung cancer: a retrospective cohort study

Objective

To find out how bacterial lung infections (BLI) affect the effectiveness of therapy and the rate of pneumonia caused by pneumonia related to checkpoint inhibitors (CIP) in patients with non-small cell lung cancer (NSCLC) who are getting immunotherapy with checkpoint inhibitors (ICIs).

Patients and methods

507 NSCLC patients who received at least two ICI treatments between June 2020 and December 2022 at the Affiliated Hospital of Kunming University of Science and Technology(AHKUST) were included in a retrospective cohort study. Based on whether there was a concurrent BLI diagnosis from high-resolution CT scans of the chest, the patients were divided into two groups: 238 in the NSCLC with BLI group (NSCLC-BLI group), and 269 in the NSCLC alone group. The collected therapeutic outcome measures included the objective response rate (ORR), progression-free survival (PFS), overall survival (OS), and the incidence rate of CIP. We analyzed the effect of BLI on the therapeutic efficacy of ICI treatment and the incidence rate of CIP in NSCLC patients.Inclusion criteria based on NSCLC patients staged I to IV according to the 8th edition of the International Association for Lung Cancer Research (IASLC).

Results

The NSCLC-BLI group showed superior ORR to the NSCLC group when treated with ICIs. Multifactorial logistic regression and Cox analyses, adjusted for confounders, identified BLI as an independent positive prognostic factor for ORR (HR=0.482, 95%CI: 0.391-0.550; P<0.001) and PFS (HR=0.619; 95%CI: 0.551-0.771; P<0.001). No correlation between BLI and OS was found. Out of 26 cases of CIP, 12 were in the NSCLC-BLI group and 14 in the NSCLC group, with no significant difference in incidence (P=0.145).

Conclusion

NSCLC patients with BLI receiving ICI treatment show superior ORR and PFS compared to NSCLC alone without an increased CIP risk, positioning BLI as a predictive factor for improved outcomes in NSCLC patients receiving ICIs. However, the study has limitations including its retrospective nature and lacking data on BLI bacteria types and levels, which could influence therapy outcomes.

Carbapenem-Resistant and ESBL-Producing Enterobacterales Emerging in Central Texas

Purpose

Carbapenem-resistant Enterobacterales (CRE) are subject to intense global monitoring in an attempt to maintain awareness of prevalent and emerging resistance mechanisms and to inform treatment and infection prevention strategies. CRE and extended-spectrum beta-lactamase (ESBL)-producing Enterobacterales are not usually examined collectively in regards to their shared pool of resistance determinants. Here, we genetically and phenotypically assess clinical isolates of CRE and extended-spectrum beta-lactamase (ESBL)-producing Enterobacterales in the growing region of Central Texas, where CRE are emergent and occurrence of non-carbapenemase-producing-CRE (non-CP-CRE) infections is increasing.

Methods

CRE (n=16) and ESBL-producing Enterobacterales (n=116) isolates were acquired from a regional hospital in Central Texas between December 2018 and January 2020. Isolates were assessed genetically and phenotypically using antibiotic susceptibility testing, targeted PCR, and whole genome sequencing.

Results

CRE infections are increasing in incidence in Central Texas, and Klebsiella pneumoniae is causing the majority of these infections. Moreover, K. pneumoniae sequence type (ST) 307 is commonly found among both non-CP-CRE and EBSL-producing strains. Isolates carry similar plasmids harboring the gene for the ESBL CTX-M-15 and belong to the global lineage, rather than the Texas lineage, of ST307. Antibiotic resistance profiles, sequence data, and clinical records suggest that porin mutations may promote the transition of ST307 isolates from ESBL-producing to non-CP-CRE. In addition to antibiotic resistance mechanisms, several CRE isolates harbor active colicinogenic plasmids, which might influence the competitiveness of these bacteria during patient colonization.

Conclusion

K. pneumoniae of the global ST307 lineage is circulating in Central Texas and is responsible for both non-CP CRE and ESBL-producing Enterobacterales infections. Enhanced surveillance is needed to understand the possible routes for the emergence of non-CP-CRE from EBSL-producing strains.

Risk factors for carbapenem-resistant Enterobacterales infection among hospitalized patients with previous colonization

BACKGROUND

We aimed to identify the risk factors for subsequent carbapenem-resistant Enterobacterales (CRE) infections in patients with initial rectal colonization with CRE.

METHODS

We conducted a retrospective case-control study on inpatients with rectal CRE colonization between January 2019 and December 2020. Clinical and microbiological data were extracted from hospital patients' medical records and the clinical microbiology laboratory. Risk factors were assessed and compared between patients with CRE colonization who had subsequent infections and those who did not have infections.

RESULTS

Among 1064 patients screened for CRE, we enrolled 205 patients with rectal CRE colonization. Among the 205 colonized bacteria, 78.5% were Klebsiella pneumoniae, with 62.9% of them producing Klebsiella pneumoniae carbapenemase (KPC). Multivariate logistic regression analysis revealed that more than three times hospitalization (p = 0.026), being in a coma (p = 0.019), and exposure to carbapenems (p = 0.015) were independent risk factors for CRE clinical infection among CRE rectal carriers.

CONCLUSION

This is the first study to report that more than three times hospitalization is an independent risk factor for subsequent CRE clinical infection in CRE intestinal carriers. Carbapenem-resistant Klebsiella pneumoniae is the most important species isolated from hospitalized CRE rectal carriers and is the most common cause of subsequent infections.

A case–control study of infections caused by Klebsiella pneumoniae producing New Delhi metallo-beta-lactamase-1: Predictors and outcomes

Introduction

Infections caused by antimicrobial-resistant bacteria are a significant cause of death worldwide, and carbapenemase-producing bacteria are the principal agents. New Delhi metallo-beta-lactamase-1 producing Klebsiella pneumoniae (KP-NDM-1) is an extensively drug-resistant bacterium that has been previously reported in Mexico. Our aim was to conduct a case–control study to describe the risk factors associated with nosocomial infections caused by K. pneumoniae producing NDM-1 in a tertiary-care hospital in Mexico.

Methods

A retrospective case–control study with patients hospitalized from January 2012 to February 2018 at the Hospital Civil de Guadalajara “Fray Antonio Alcalde” was designed. During this period, 139 patients with a culture that was positive for K. pneumoniae NDM-1 (cases) and 486 patients hospitalized in the same department and on the same date as the cases (controls) were included. Data were analyzed using SPSS v. 24, and logistic regression analysis was conducted to calculate the risk factors for KP-NDM-1 infection.

Results

One hundred and thirty-nine case patients with a KP-NDM-1 isolate and 486 control patients were analyzed. In the case group, acute renal failure was a significant comorbidity, hospitalization days were extended, and significantly more deaths occurred. In a multivariate analysis of risk factors, the independent variables included the previous use of antibiotics (odds ratio, OR = 12.252), the use of a urinary catheter (OR = 5.985), the use of a central venous catheter (OR = 5.518), the use of mechanical ventilation (OR = 3.459), and the length of intensive care unit (ICU) stay (OR = 2.334) as predictors of infection with NDM-1 K. pneumoniae.

Conclusion

In this study, the previous use of antibiotics, the use of a urinary catheter, the use of a central venous catheter, the use of mechanical ventilation, and ICU stay were shown to be predictors of infection with NDM-1 K. pneumoniae and were independent risk factors for infection with NDM-1 K. pneumoniae.

Differences in the Distribution of Species, Carbapenemases, Sequence Types, Antimicrobial Heteroresistance and Mortality Rates Between Pediatric and Adult Carbapenemase-Producing Enterobacterales in Bloodstream Infections

The dissemination of carbapenemase-producing Enterobacterales (CPE) is worrisome given their scarce treatment options. CPE bloodstream infections (BSIs) had a high mortality rate in adults, and there was little data on pediatric CPE-BSIs around the world. We comprehensively explored the differences in the clinical and microbiological characteristics between pediatric and adult CPE-BSIs. Forty-eight pediatric and 78 adult CPE-BSIs cases were collected. All-cause 30 day-mortality in children with CPE-BSIs (14.6%, 7/48) was significantly lower than that in adult patients (42.3%, 33/78, p = 0.001). The subgroup in adults empirically treated with tigecycline as an active drug displayed a significantly higher 30-days crude mortality (63.3%, 19/30) than the subgroup treated without tigecycline (29.2%, 14/48, p = 0.003). K. pneumoniae was the most prevalent species in both the pediatric (45.8%, 22/48) and adult populations (64.1%, 50/78), with discrepant carbapenemase genes in each population: 95.4% (21/22) of the pediatric K. pneumoniae isolates carried bla_NDM, while 82.0% (41/50) of the adult strains harbored bla_KPC. The ratio of E. coli in children (37.5%) was significantly higher than that in adults (12.8%, p = 0.002). In both populations, the majority of E. coli expressed bla_NDM, particularly bla_NDM−5. With statistical significance, bla_NDM was much more common in children (95.8%, 46/48) than in adults (34.6%, 27/78). The rate of multiple-heteroresistance phenotypes in children was as high as 87.5%, which was much lower in adults (57.1%). Agar dilution checkboard experiment against one pediatric carbapenemase-producing E. coli isolates showed that the combination of amikacin and fosfomycin yielded an additive effect. Overall, K. pneumoniae was the most common CPE-BSIs pathogen in both populations, with NDM-producing K. pneumoniae and KPC-producing ST11 K. pneumoniae being the most prevalent species in children and adults, respectively. E. coli was more prevalent in children than in adults, yet bla_NDM−5 was the most common carbapenem-resistant mechanism in E. coli in both populations. The wide range of multiple-heteroresistance combination traits found in different pathogen species from different host populations should provide a good foundation for future combination therapy design. Further investigations from more CPE isolates of various species are needed to evaluate the possible in vitro partial synergy of the amikacin and fosfomycin combination.

Epidemiology and mechanisms of tigecycline- and carbapenem- resistant Enterobacter cloacae in Southwest China: a five-year retrospective study

BACKGROUND

The prevalence and molecular epidemiology of tigecycline resistance in carbapenem-resistant Enterobacter cloacae (CREC) in mainland China is unknown. In this study, we aimed to investigate the molecular characteristics and resistance mechanism of tigecycline-resistant CREC (TCREC) in Southwest China.

METHODS

We conducted a five-year retrospective study. TCREC isolates were subjected to antimicrobial susceptibility testing, pulsed-field gel electrophoresis, and multilocus sequence typing. We determined the presence of genes, deficiency of outer membrane proteins, and expression of efflux pumps using polymerase chain reaction (PCR), reverse transcription-polymerase chain reaction (RT-PCR), and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE).

RESULTS

We found that a high incidence rate of 21.7% (36/166) of isolates were positive for TCREC. All isolates were resistant to ertapenem whereas 67% remained susceptible to imipenem and meropenem. ST88 (10/36, 27.8%) was predominant and associated with moderate resistance to tigecycline and high resistance to carbapenems, followed by ST256 (3/36, 8.3%), ST78 (2/36, 5.6%), ST577 (2/36, 5.6%), and ST102 (2/36, 5.6%). bla_NDM-1 (6/36, 16.6%) carriers was the most common carbapenemase gene and ST88 (5/6, 83.3%) was the most common type, followed by bla_IMP-8 (n=3/36, 8.3%). Coexistence of extensive-spectrum β-lactamase (ESBL) genes and outer membrane protein OmpF and/or OmpC loss were found in 27 out of 36 isolates, in addition, increased co-expression of efflux pump genes acrB and oqxA was identified in 25 out of 36 isolates, which may together contribute to co-resistance to carbapenem and tigecycline.

CONCLUSION

Most ST88 strains carried carbapenemases, especially New Delhi metallo-β-lactamase 1 (NDM-1). Overexpression of efflux pumps contributed to tigecycline resistance. The presence of carbapenemase and/or ESBL genes and lack of outer membrane proteins, but not overexpression of efflux pumps, may confer carbapenem resistance. Reasonable supervision and management the epidemic of TCREC will help to stem the transmission of the isolates.

Clinical and Microbiological Characterization of Carbapenem-Resistant Enterobacteriales: A Prospective Cohort Study

Aim: We aim to depict the clinicoepidemiological and molecular information of carbapenem-resistant Enterobacteriales (CRE) in Chongqing, China.

Methods: We performed a prospective, observational cohort study, recruiting inpatients diagnosed with CRE infections from June 1, 2018, to December 31, 2019. We carried out strain identification and molecular characterization of CRE. eBURST analysis was conducted to assess the relationships among the different isolates on the basis of their sequence types (STs) and associated epidemiological data using PHYLOViZ. Clinical parameters were compared between the carbapenemase-producing Enterobacteriales (CPE) and non-CPE group.

Findings: 128 unique CRE isolates from 128 patients were collected during the study period: 69 (53.9%) CPE and 59 (46.1%) non-CPE. The majority of CPE isolates were bla_KPC-2 (56.5%), followed by bla_NDM (39.1%) and bla_IMP (5.8%). Klebsiella pneumoniae carbapenemase (KPC)–producing clonal group 11 Klebsiella pneumoniae (K. pneumoniae) was the most common CPE. Antibiotic resistance was more frequent in the CPE group than in the non-CPE group. Independent predictors for CPE infection were ICU admission and hepatobiliary system diseases. Although, there was no significant difference in desirability of outcome ranking (DOOR) outcomes between the two groups. At 30 days after index culture, 35 (27.3% ) of these patients had died.

Conclusion: CRE infections were related to high mortality and poor outcomes, regardless of CRE subgroups. CPE were associated with prolonged ICU stays and had different clinical and microbiological characteristics than non-CPE. The identification of CPE/non-CPE and CRE resistance mechanisms is essential for better guidance of the clinical administration of patients with CRE infections.

Risk factors and mortality associated with multidrug-resistant gram-negative bacterial infection in adult patients with abdominal surgery

BACKGROUND

Multidrug-resistant (MDR) gram-negative bacterial (GNB) infections remain a significant cause of morbidity and mortality among surgical patients. The objective of our study was to recognize the risk factors for MDR GNB infection in patients with abdominal surgery and determine the predictors independently associated with death.

METHODS

From 2010 to 2017, a retrospective cohort study was conducted among patients with abdominal surgery admitted in surgical intensive care unit (ICU). Patients with GNB infections were included for analyses.

RESULTS

A total of 364 patients with abdominal surgery experienced GNB infections, among them, 117 (32.1%) were MDR GNB infection. Of 133 MDR GNB isolates, the most frequent isolate was Escherichia coli (45.1%). Patients with MDR GNB infection had significantly longer ventilator days and hospital stay, as well as higher 30-day and in-hospital mortality compared to non-MDR GNB patients. Multivariable analysis showed longer length of pre-ICU stay, surgical re-exploration, receipt of group 2 carbapenems (e.g. imipenem, meropenem and doripenem) and fluoroquinolones, and higher total bilirubin were independent risk factors for the acquisition of MDR GNB infection. Predictors for 30-day mortality among patients with MDR GNB infection were chronic kidney disease, receipt of group 2 carbapenems and inappropriate empirical antimicrobial therapy.

CONCLUSIONS

This study provides important information about the risk factors for subsequent MDR GNB infection and 30-day mortality among the patients with abdominal surgery.

Emerging Threat of Multidrug Resistant Pathogens From Neonatal Sepsis

Multidrug-resistant (MDR) pathogens are responsible for a substantial burden of morbidity and mortality from neonatal sepsis; however, data on these sepsis-related pathogens among hospitalized neonates in China are not well characterized. In this study, a total of 240 strains were isolated from four Women and Children's hospitals in Southwest China between 2014 and 2019. Of these included pathogens, 104 (43.33%) were gram-positive bacteria, 129 (53.75%) were gram-negative bacteria, and 7 (2.92%) were fungi. Escherichia coli (E. coli, 34.01%) and Klebsiella pneumoniae (K. pneumoniae, 15.35%) were the main pathogen of neonate bacteremia. ST167 were the most prevalent STs in E. coli and ST11 in K. pneumoniae. Our study found that E. coli (62.71%) was the predominate pathogen of early-onset sepsis, among which 64.86% were MDR. Late-onset sepsis was mainly caused by K. pneumoniae (28.31%) and E. coli (24.78%), with showing that 78.33% of these pathogens were MDR. Notably, the prevalence of EO/LO pathogens were quite different from Indian and south of China. Moreover, we found that bla _CTX-M (42.06%) was most dominant resistant genes with about a third isolates (31.09%) were positive for bla _CTX-M-15. All the carbapenem-resistant K. pneumoniae were positive for NDM-1. Moreover, late-onset sepsis and antibiotic exposure were significantly associated with MDR infection. Emerging multi-resistant pathogens of sepsis posts a serious threat to neonatal outcomes and emphasizes an urgent need to control their further spread.

Deep learning model for prediction of extended-spectrum beta-lactamase (ESBL) production in community-onset Enterobacteriaceae bacteraemia from a high ESBL prevalence multi-centre cohort

Adequate empirical antimicrobial coverage is instrumental in clinical management of community-onset Enterobacteriaceae bacteraemia in areas with high ESBL prevalence, while balancing the risk of carbapenem overuse and emergence of carbapenem-resistant organisms. It is unknown whether machine learning offers additional advantages to conventional statistical methods in prediction of ESBL production. To develop a validated model to predict ESBL production in Enterobacteriaceae causing community-onset bacteraemia. 5625 patients with community-onset bacteraemia caused by Escherichia coli, Klebsiella species and Proteus mirabilis during 1 January 2015-31 December 2019 from three regional hospitals in Hong Kong were included in the analysis, after exclusion of blood cultures obtained beyond 48 h of admission. The prevalence of ESBL-producing Enterobacteriaceae was 23.7% (1335/5625). Deep neural network and other machine learning algorithms were compared against conventional statistical model via multivariable logistic regression. Primary outcomes compared consisted of predictive model area under curve of receiver-operator characteristic curve (AUC), and macro-averaged F1 score. Secondary outcomes included sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Deep neural network yielded an AUC of 0.761 (95% CI 0.725-0.797) and F1 score of 0.661 (95% CI 0.633-0.689), which was superior to logistic regression (AUC 0.667 (95% CI 0.627-0.707), F1 score 0.596 (95% CI 0.567-0.625)). Deep neural network had a specificity of 91.5%, sensitivity of 37.5%, NPV of 82.5%, and PPV of 57.9%. Deep neural network is superior to logistic regression in predicting ESBL production in Enterobacteriaceae causing community-onset bacteraemia in high-ESBL prevalence area. Machine learning offers clinical utility in guiding judicious empirical antibiotics use.

Analysis of Pathogen Distribution and Its Antimicrobial Resistance in Bloodstream Infections in Hospitalized Children in East China, 2015-2018

This study analyzed the pathogen distribution in bloodstream-infected (BSI) children hospitalized in Shandong Province from 2015 to 2018, to identify prevention strategies and select empiric antimicrobial therapy for BSI in children. Blood sample data from 14 107 children from 162 hospitals of Shandong Province were obtained from the China Antimicrobial Resistance Surveillance System and analyzed with WHONET 5.6 software. The results of the blood culture test showed the growth of 70.6% Gram-positive and 29.4% Gram-negative bacteria. Of the 14 107 blood isolates, 59.3% were collected from males and 40.7% were from females. Coagulase-negative staphylococci (47.1%) were the most commonly distributed pathogens. The distribution of pathogens varied according to age group and season. All Staphylococcus isolates were susceptible to vancomycin, teicoplanin and linezolid. Clinically, significant declines in penicillin-resistant Streptococcus pneumonia and carbapenem-resistant Escherichia coli were observed during the study period; however, detection rates of carbapenem-resistant Klebsiella pneumoniae increased over time (p < 0.05). Empiric antimicrobial therapy should be prescribed according to corresponding regional pediatric antimicrobial-resistant data.

A Retrospective Analysis of Risk Factors and Patient Outcomes of Bloodstream Infection with Extended-Spectrum β-Lactamase-Producing Escherichia coli in a Chinese Tertiary Hospital

Objective

The present study assessed risk factors and patient outcomes of bloodstream infection (BSI) caused by extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (E. coli).

Methods

A retrospective study was performed to analyze risk factors and patient outcomes of BSI caused by extended-spectrum β-lactamase-producing Escherichia coli (ESBL-EC) in one Chinese tertiary hospital over a 7.5-year period. The clinical characteristics of patients infected with ESBL-producing and non-ESBL-producing E. coli were compared. Predictors of 30-day mortality in patients with E. coli BSI were also identified in our study.

Results

The results of drug sensitivity showed that quinolones, aminoglycosides, β-lactam/β-lactamase inhibitor combinations (BLICs) and trimethoprim/sulfamethoxazole exhibited significant differences between the ESBL and non-ESBL groups. Of the 963 patients with E. coli BSI, 57.6% developed ESBL-EC. Multivariate analysis showed that biliary tract infection (BTI) [P<0.001,OR (95% CI):1.798 (1.334–2.425)], urinary tract obstructive disease [P=0.001,OR (95% CI):2.106 (1.366–3.248)], surgery within 3 months [P=0.002,OR (95% CI):1.591 (1.178–2.147)], hospitalization within 3 months [P<0.001,OR (95% CI):2.075 (1.579–2.725)], ICU admission [P=0.011,OR (95% CI):1.684 (1.124–2.522)] and history of cephalosporin use [P=0.006,OR (95% CI):3.097 (1.392–6.891)] were statistically significant. In mortality analysis, aCCI>2 [P=0.016,OR (95% CI): 2.453 (1.179–5.103)], gastrointestinal catheterization [P=0.004, OR (95% CI): 2.525 (1.333–4.782)] were significantly associated with 30-day mortality. According to Kaplan-Meier survival analysis, we found that in SOFA<2 group and SOFA≥2 group, the mortality rate of patients treated with BLICs were lower than that of carbapenems(P<0.05).

Conclusion

This study showed that BTI, urinary tract obstructive disease, surgery within 3 months, hospitalization within 3 months, ICU admission and cephalosporin exposure were independent risk factors for the emergence of ESBL-EC BSI. Analysis of risk factors for 30-day mortality revealed that the factors independently associated with a higher risk of mortality were aCCI>2, gastrointestinal catheterization. Compared to carbapenems, the BLICs had preferable effect to treat patients with ESBL-EC BSI. Notably, patients with severe illness were inlcined to use carbapenems, which affected the analysis results. Therefore, we suggest that BLICs could be recommended to treat mild patients with ESBL-EC bacteremia.

Clinical and Microbiological Prognostic Factors of in-Hospital Mortality Caused by Hypervirulent Klebsiella pneumoniae Infections: A Retrospective Study in a Tertiary Hospital in Southwestern China

Purpose

Hypervirulent klebsiella pneumoniae (hvKP) is responsible for various invasive diseases and associated with high mortality. However, the clinical and microbiological factors of hvKP infection that influence prognosis have not been well studied. The purpose of this study was to evaluate the prognostic factors for in-hospital mortality of patients with hvKP infections, mainly focusing on clinical and microbiological characteristics.

Methods

A retrospective study was conducted in hvKP strains which positive for iucA and string test. According to the clinical outcomes during hospitalization, hvKP-infected patients were divided into non-survivor and survivor groups. The clinical characteristics, capsule types, multi-locus sequence types (MLST), virulence genes and antimicrobial susceptibility were compared between those of the two groups.

Results

A total of 135 patients were demonstrated to be with hvKP infections, with a prevalence rate of 22% among all the klebsiella pneumoniae infected cases. Sixteen of these patients died during hospitalization, with an in-hospital mortality rate of 11.9%. Univariate analysis confirmed that admission to the intensive care unit (ICU) (p=0.008), antimicrobial resistance of hvKP to ampicillin/sulbactam (p=0.028), cefepime (p=0.033), aztreonam (p=0.049) and harboring iroN gene (p=0.023) were associated with in-hospital mortality. On the contrary, the rmpA gene showed an inverse association with in-hospital mortality (p=0.017). Multivariate logistic regression analysis revealed that ICU admission (odds ratio [OR]=3.452, 95% confidence interval [CI]=1.052–11.329; P=0.041) and iroN carriage (OR=9.278, 95% CI=1.654–52.035; P=0.011) were independent prognostic factors for the in-hospital mortality of patients with hvKP infections.

Conclusion

Emerging hvKP infection may lead to relatively high in-hospital mortality. ICU admission and iroN carriage were independent prognostic factors for the in-hospital mortality of patients with hvKP infections.

Risk Factors for Subsequential Carbapenem-Resistant Klebsiella pneumoniae Clinical Infection Among Rectal Carriers with Carbapenem-Resistant Klebsiella pneumoniae

Purpose

Carbapenem-resistant Klebsiella pneumoniae (CRKP) infection has become a critical clinical concern for its high mortality. Rectal carriage of CRKP has been reported playing an important role in CRKP infection; however, the extent to which carrier develops clinical CRKP infection is unclear. This study aimed to identify risk factors for developing subsequential CRKP clinical infection in rectal carriers with CRKP.

Patients and Methods

Patients were screened for rectal carriage of CRKP in a tertiary university hospital; then, rectal CRKP carriers were divided into case group (those who developed subsequential clinical infection) and control group. Demographics, comorbid conditions, invasive procedures, antimicrobial exposure and other clinical parameters of those two groups were compared and analyzed using univariate and multivariate logistic regression analyses. Antimicrobial susceptibility profile and carbapenemase phenotype/genotype of those CRKP isolates were determined. MLST was applied to elucidate the molecular epidemiology of rectal CRKP isolates and clinical infection ones.

Results

Eight hundred and thirty-five patients were screened for rectal CRKP carriage. A total of 62 CRKP rectal carriers were identified; among them, 37.1% (23/62) developed CRKP clinical infection. CRKP isolates were resistant to most of the tested antimicrobial agents. ST11 was the dominant MLST type in rectal CRKP isolates (71.0%), and all the 23 clinical infection isolates were ST11. Multivariate analysis revealed that admission to the intensive care unit (ICU) (OR, 6.753; P=0.006), being in coma condition (OR, 11.085; P=0.015) and receiving central venous catheter (OR, 8.628; P=0.003) were independent risk factors for progressing to subsequential CRKP infection among those rectal carriers.

Conclusion

This study identified independent risk factors for developing subsequential CRKP clinical infection among CRKP rectal carriers, with being in coma condition as a new finding. It would help clinician target those high-risk rectal CRKP-colonized patients for prevention of subsequential clinical infection.

Genetic diversity and in vitro activity of ceftazidime/avibactam and aztreonam/avibactam against imipenem-resistant Enterobacteriaceae isolates in Southwest China: A single-centre study

OBJECTIVES

The aim of this study was to investigate the molecular mechanisms of imipenem resistance in Enterobacteriaceae and to assess the antimicrobial activities of ceftazidime/avibactam (CAZ/AVI) and aztreonam/avibactam (ATM/AVI) against imipenem-resistant clinical isolates in a tertiary hospital in China.

METHODS

A total of 91 imipenem-resistant Enterobacteriaceae were collected and genes encoding carbapenemases, ESBLs, AmpC β-lactamases and porins were detected using PCR. MICs and susceptibility were determined using in-house-prepared broth microdilution panels and were interpreted according to CLSI breakpoints.

RESULTS

Imipenem-resistant isolates comprising 54 Klebsiella pneumoniae, 18 Escherichia coli, 8 Enterobacter cloacae, 6 Serratia marcescens, 3 Klebsiella oxytoca and 2 Klebsiella aerogenes were collected independently. Five different carbapenemase genes were identified, namely bla_KPC-2 (n = 60), bla_NDM-5 (n = 14), bla_NDM-1 (n = 11), bla_KPC-3 (n = 4) and bla_IMP-4 (n = 1). Among the 91 carbapenem-resistant Enterobacteriaceae (CRE), 85 isolates harboured at least one ESBL and/or AmpC gene, including 5 strains without carbapenemase-encoding genes. Moreover, 31 K. pneumoniae carried ompK35 and/or ompK36 mutations. MLST results showed that the K. pneumoniae belonged to 12 different STs, with ST11 being predominant (29/54; 53.7%). Overall, 17.6%, 25.3%, 41.8%, 65.9% and 100% of the CRE strains were susceptible to amikacin, trimethoprim/sulfamethoxazole, tetracycline, CAZ/AVI and ATM/AVI, respectively.

CONCLUSION

This study revealed that CRE isolates differ significantly in their species, STs, porins and carbapenemase genes in a single Chinese hospital. ATM/AVI exhibited potent activity against CRE isolates, even for the most notorious double-carbapenemase-producers with porin defects, whereas CAZ/AVI was active against all the non-metallo-β-lactamase-producing isolates.

Carbapenem-Resistant Enterobacter cloacae Causing Nosocomial Infections in Southwestern China: Molecular Epidemiology, Risk Factors, and Predictors of Mortality

Background

The emergence and spread of carbapenem-resistant Enterobacter cloacae (CR-ECL) have posed a serious threat to clinical management. This retrospective study assessed the epidemiological characteristics of CR-ECL to explore the risk factors and predictors of mortality in patients with CR-ECL infection.

Methods

We performed a retrospective 1:2 case-control study of hospitalized patients from January 2014 to December 2017. A total of 85 consecutive unique CR-ECL strains comprised the case group, and 170 matched patients with carbapenem-susceptible Enterobacter cloacae (CS-ECL) infection at the same period as the control group. Isolates were screened for potential resistance genes by polymerase chain reaction (PCR) and molecular typing was performed by multilocus sequence typing (MLST).

Results

The results of drug resistance gene detection showed that blaNDM-1 was the most common carbapenem resistance gene. The MLST results showed that ST51 was the predominant epidemic type, followed by ST88. ICU admission (P<0.001), drainage tube (P=0.002), central venous catheter (P=0.005), and carbapenem exposure (P=0.003) were independent risk factors for CR-ECL infection. Significant predictors for 28-day mortality included solid tumours (P=0.005), septic shock (P=0.019), and mechanical ventilation (P=0.027).

Conclusion

Our study indicated that ST51 and ST88, which are closely related, were the predominant epidemic types of CR-ECL producing blaNDM-1 in southwestern China. Strengthening the surveillance of patients with solid tumours, septic shock and mechanical ventilation is an urgent need.

CP-CRE/non-CP-CRE Stratification And CRE Resistance Mechanism Determination Help In Better Managing CRE Bacteremia Using Ceftazidime-Avibactam And Aztreonam-Avibactam

Purpose

This observational study aimed to identify the independent risk factors for both the acquisition and mortality of carbapenemase-producing carbapenem-resistant Enterobacteriaceae (CP-CRE) bacteremia and further assess the in vitro antimicrobial activities of ceftazidime–avibactam (CAZ/AVI) and aztreonam–avibactam (ATM/AVI) against recent CRE bacteremic isolates.

Patients and methods

This observational study was conducted to reveal the risk factors and mortality rate for CP-CRE bacteremia between 2012 and 2018 and also evaluate the in vitro antimicrobial activities of CAZ/AVI and ATM/AVI against recent CRE bacteremic isolates from 2016 to 2018.

Results

A total of 81 non-repetitive isolates were collected from 2012 to 2018, with 67.90% (55/81) being CP-CRE. Old age (P = 0.01), transfusion [odds ratio (OR): 17.19; 95% CI: 3.15–93.72; P = 0.001], longer ICU stay (P = 0.02), cancer (OR: 15.91; 95% CI: 3.56–71.37; P < 0.001), and previous carbapenem exposure (OR: 27.86; 95% CI: 5.03–154.19; P = 0.001) were identified as independent risk factors for the acquisition of CP-CRE bacteremia compared with the ESBL bacteremia. The in vitro antimicrobial activities of CAZ/AVI and ATM/AVI against the CRE bacteremic isolates from 2016 to 2018 showed a respective susceptibility rate of 70.68% (41/58) and 100.00% (58/58).

Conclusion

The findings indicated that both CP-CRE/non-CP-CRE stratification and CRE resistance mechanism determination were necessary for better guiding the clinical management of CRE bacteremia: ATM/AVI probably works with both non-CP-CRE and CP-CRE bacteremia, even the most notorious double-carbapenemase producer with porin loss/deficiency, whereas CAZ/AVI works with most of the non-CP-CRE and KPC-producers in the region.

Shifting trends and age distribution of ESKAPEEc resistance in bloodstream infection, Southwest China, 2012-2017

Background

ESKAPEEc contribute to a majority of bloodstream infections (BSIs) and their antibiogram have changed overtime, while data concerning about these alterations are lacking in China. Added that a paucity of studies referred to ESKAPEEc in pediatric BSIs, our study aimed to demonstrate the longitudinal alterations of ESKAPEEc distribution and antibiogram in adult and pediatric BSIs in Southwest China.

Methods

A multicenter retrospective surveillance study was launched from 2012 to 2017. Data of China Antimicrobial Resistance Surveillance System (CARSS) was analyzed by Whonet 5.6 and Graphpad Prism 6 Software. Chi-square test or Fisher’s exact test was used to examine and compare temporal changes.

Results

A total of 32,259 strains was isolated, with 17.4% from pediatric BSIs. ESKAPEEc contributed to 58.67% (18,924/32,259) of BSIs, with 65.3% of adult BSIs and 27.2% of pediatric BSIs. Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae) were the two predominant species. Carbapenem resistance was prevalent in 0.76, 4.60, 9.47,13.66, 59.47% of E. coli, K. pneumoniae, Enterobacter cloacae, Pseudomonas aeruginosa (P. aeruginosa) and Acinetobacter baumannii (A. baumannii), respectively. The proportions of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VREFM) were 28.91% and 2.20%, respectively. Between 2012-2014 and 2015–2017, E. coli and K. pneumonia showed significantly increased resistance rates to imipenem but decreased to ceftriaxone and ceftazidime, while A. baumannii exhibited reduced resistances to almost all the beta-lactams tested. The prevalence of antimicrobial resistance to most of agents against Gram-positive ESKAPEEc did not significantly varied during the same timeframe. In comparison with those from adult BSIs, K. pneumoniae from pediatric BSIs exhibited high resistance rates to all the beta-lactams tested, especially to carbapenems (12.79% vs 3.87%), while A. baumannii showed low resistance rates to all the agents.

Conclusions

Ongoing burden of ESKAPEEc in BSIs and increasing trend of imipenem resistance in E. coli and K. pneumoniae call for continued surveillance. Carbapenems are still active against Gram-negative ESKAPEEc, except for A. baumannii and vancomycin or linezolid is still effective against Gram-positive ESKAPEEc. Carbapenem-resistant K. pneumoniae in children and carbapenem-resistant A. baumannii in adults necessitate effective antimicrobial strategies in consideration of age stratification.

Molecular Epidemiology and Risk Factors of Ventilator-Associated Pneumonia Infection Caused by Carbapenem-Resistant Enterobacteriaceae

Ventilator-associated pneumonia (VAP) infection caused by carbapenem-resistant Enterobacteriaceae (CRE) is becoming more prevalent, thus seriously affecting patient outcomes. In this paper, we studied the drug resistance mechanism and epidemiological characteristics of CRE, and analyzed the infection and prognosis factors of VAP caused by CRE, to provide evidence for effective control of nosocomial infection in patients with VAP. A total of 58 non-repetitive CRE strains of VAP were collected from January 2016 to June 2018. To explore the risk factors of CRE infection, 1:2 group case control method was used to select non CRE infection patients at the same period as the control group. Among the 58 CRE strains, the most common isolates included Klebsiella pneumoniae and Escherichia coli. All strains were sensitive to polymyxin B, which features better sensitivity to other antibiotics such as minocycline, trimethoprim/sulfamethoxazole, and amikacin. Multiple drug resistance genes were detected at the same time in most strains. KPC-2 was the most common carbapenemase-resistant gene in Klebsiella pneumoniae, whereas NDM-1 was more common in Escherichia coli. The risk factors correlated with CRE infection included intensive care unit (ICU) occupancy time >7 days (OR = 2.793; 95% CI 1.439~5.421), antibiotic exposure during hospital stay including those to enzyme inhibitors (OR = 1.977; 95% CI 1.025~3.812), carbapenems (OR = 3.268; 95% CI 1.671~6.392), antibiotic combination therapy(OR = 1.951; 95% CI 1.020~3.732), and nerve damage (OR = 3.013; 95% CI 1.278~7.101). Multivariable analysis showed that ICU stay >7 days (OR = 1.867; 95% CI 1.609~20.026), beta-lactamase inhibitor antibiotics (OR = 7.750; 95% CI 2.219~27.071), and carbapenem (OR = 9.143; 95% CI 2.259~37.01) are independent risk factors for VAP carbapenem caused by Carbapenem-resistant Enterobacteriaceae. A high resistance rate of CRE isolated from VAP indicated that the infected patients featured higher mortality and longer hospital stay time than the control group. Multiple risk factors for CRE infection and their control can effectively prevent the spread of VAP.