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

Predictors of Mortality, Drug Resistance, and Determinants among Carbapenem-Resistant Enterobacteriales Infections in Chinese Elderly Patients

Elderly patients with carbapenem-resistant Enterobacteriales (CRE) infections represent considerable mortality rates. But data on the risk factors for the death of elderly patients following such infection remain limited. We aimed to assess the clinical outcomes, identify mortality-associated risk factors, and determine the antibiotic resistance and resistance genes of isolates for these patients. Hospitalized patients aged ≥65 years with CRE infection from January 2020 to December 2020 were retrospectively reviewed. Isolates identification and molecular characterization of CRE were carried out. Logistic regression analysis was applied to assess the potential factors associated with mortality. Of the 123 elderly patients with CRE infection included in our study, the all-cause mortality rate was 39.8% (49/123). The most prevalent pathogen was carbapenem-resistant Klebsiella pneumoniae (CRKP, 116 of 123). The overall rates of multidrug-resistant (MDR) and extensively drug-resistant (XDR) were 100.0% and 66.7%. All CRE isolates exclusively harbored a singular variant of carbapenemase gene, such as bla KPC-2, bla IMP-4, bla NDM-5, or bla OXA-48, while 98.4% of isolates harbored more than one β-lactamase gene, of which 106 (86.2%) isolates harbored bla CTX-M, 121 (98.4%) isolates harbored bla TEM, and 116 (94.3%) isolates harbored bla SHV. Multivariable logistic regression analysis revealed that mechanical ventilation (adjusted odds ratio (AOR) = 33.607, 95% confidence interval (CI): 4.176-270.463, P < 0.001), use of tigecycline during hospitalization (AOR = 5.868, 95% CI: 1.318-26.130, P = 0.020), and APACHE II score (AOR = 1.305, 95% CI: 1.161-1.468, P < 0.001) were independent factors associated with increasing the mortality of patients with CRE infection, while admission to intensive care unit (ICU) during hospitalization (AOR = 0.046, 95% CI: 0.004-0.496, P = 0.011) was a protective factor. CRE-infected elderly patients with mechanical ventilation, use of tigecycline during hospitalization, and high APACHE II score were related to poor outcomes. The isolates carried various antibiotic genes and presented high antibiotic resistance. These findings provide crucial guidance for clinicians to devise appropriate strategies for treatment.

Genomic Study of High-Risk Clones of Enterobacter hormaechei Collected from Tertiary Hospitals in the United Arab Emirates

Enterobacter hormaechei has emerged as a significant pathogen within healthcare settings due to its ability to develop multidrug resistance (MDR) and survive in hospital environments. This study presents a genome-based analysis of carbapenem-resistant Enterobacter hormaechei isolates from two major hospitals in the United Arab Emirates. Eight isolates were subjected to whole-genome sequencing (WGS), revealing extensive resistance profiles including the blaNDM-1, blaOXA-48, and blaVIM-4 genes. Notably, one isolate belonging to ST171 harbored dual carbapenemase genes, while five isolates exhibited colistin resistance without mcr genes. The presence of the type VI secretion system (T6SS), various adhesins, and virulence genes contributes to the virulence and competitive advantage of the pathogen. Additionally, our isolates (87.5%) possessed ampC β-lactamase genes, predominantly blaACT genes. The genomic context of blaNDM-1, surrounded by other resistance genes and mobile genetic elements, highlights the role of horizontal gene transfer (HGT) in the spread of resistance. Our findings highlight the need for rigorous surveillance, strategic antibiotic stewardship, and hospital-based WGS to manage and mitigate the spread of these highly resistant and virulent pathogens. Accurate identification and monitoring of Enterobacter cloacae complex (ECC) species and their resistance mechanisms are crucial for effective infection control and treatment strategies.

Clinical Characteristics, Prognosis and Treatment of Bloodstream Infections with Enterobacter Cloacae Complex in a Chinese Tertiary Hospital: A Retrospective Study

Objective

This research aimed to analyze the clinical characteristics, prognosis, and antimicrobial treatment of bloodstream infections (BSI) caused by Enterobacter cloacae complex (ECC).

Methods

The clinical data of patients with bloodstream infections caused by Enterobacter cloacae complex from April 2017 to June 2023 were collected retrospectively. These data were then analyzed in subgroups based on the detection results of extended-spectrum β-lactamase (ESBL), 30-day mortality, and the type of antimicrobial agent used (β-lactam/β-lactamase inhibitor combinations (BLICs) or carbapenems).

Results

The proportion of ESBL-producing Enterobacter cloacae complex was 32.5% (37/114). Meanwhile, ICU admission, receiving surgical treatment within 3 months, and biliary tract infection were identified as risk factors for ESBL-producing ECC-BSI. Additionally, immunocompromised status and Sequential Organ Failure Assessment (SOFA) score ≥ 6.0 were identified as independent risk factors of 30-day mortality in patients with ECC-BSI (n = 108). Further analysis in BSI patients caused by non-ESBL-producing ECC revealed that patients treated with BLICs (n = 45) had lower SOFA scores and lower incidence of hypoproteinemia and sepsis compared with patients treated with carbapenems (n = 20). Moreover, in non-ESBL-producing ECC-BSI patients, the univariate Cox regression analysis indicated a significantly lower 30-day mortality rate in patients treated with BLICs compared to those treated with carbapenems (hazard ratios (HR) [95% CI] 0.190 [0.055-0.662], P = 0.009; adjusted HR [95% CI] 0.106 [0.013-0.863], P = 0.036).

Conclusion

This study investigated the factors influencing the susceptibility to infection by ESBL-producing strains and risk factors for 30-day mortality in ECC-BSI patients. The results revealed that ESBL-negative ECC-BSI patients treated with BLICs exhibited significantly lower 30-day mortality compared to those treated with carbapenems. BLICs were found to be more effective in ECC-BSI patients with milder disease (ESBL-negative and SOFA ≤6.0).

Alkyl deoxyglycoside-polymyxin combinations against critical priority carbapenem-resistant gram-negative bacteria

The escalating antimicrobial resistance crisis urges the development of new antibacterial treatments with innovative mechanisms of action, particularly against the critical priority carbapenem-resistant Acinetobacter baumannii (CRAB), Pseudomonas aeruginosa (CRPA) and Enterobacteriaceae (CRE). Membrane-disrupting dodecyl deoxyglycosides have been reported for their interesting phosphatidylethanolamine-associated bactericidal activity against Gram-positive strains; however, their inability to penetrate the Gram-negative outer membrane (OM) renders them useless against the most challenging pathogens. Aiming to repurpose alkyl deoxyglycosides against Gram-negative bacteria, this study investigates the antimicrobial effects of five reference compounds with different deoxygenation patterns or anomeric configurations in combination with polymyxins as adjuvants for enhanced OM permeability. The generation of the lead 4,6-dideoxy scaffold was optimized through a simultaneous dideoxygenation step and applied to the synthesis of a novel alkyl 4,6-dideoxy C-glycoside 5, herein reported for the first time. When combined with subtherapeutic colistin concentrations, most glycosides demonstrated potent antimicrobial activity against several multidrug-resistant clinical isolates of CRAB, CRE and CRPA exhibiting distinct carbapenem resistance mechanisms, together with acceptable cytotoxicity against human HEK-293T and Caco-2 cells. The novel 4,6-dideoxy C-glycoside 5 emerged as the most promising prototype structure for further development (MIC 3.1 μg/mL when combined with colistin 0.5 μg/mL against CRPA or 0.25 μg/mL against several CRE and CRAB strains), highlighting the potential of C-glycosylation for an improved bioactive profile. This study is the first to show the potential of IM-targeting carbohydrate-based compounds for the treatment of infections caused by MDR Gram-negative pathogens of clinical importance.

Ruthenium(II) polypyridyl complexes as emerging photosensitisers for antibacterial photodynamic therapy

Photodynamic therapy (PDT) has recently emerged as a potential valuable alternative to treat microbial infections. In PDT, singlet oxygen is generated in the presence of photosensitisers and oxygen under light irradiation of a specific wavelength, causing cytotoxic damage to bacteria. This review highlights different generations of photosensitisers and the common characteristics of ideal photosensitisers. It also focuses on the emergence of ruthenium and more specifically on Ru(II) polypyridyl complexes as metal-based photosensitisers used in antimicrobial photodynamic therapy (aPDT). Their photochemical and photophysical properties as well as structures are discussed while relating them to their phototoxicity. The use of Ru(II) complexes with recent advancements such as nanoformulations, combinatory therapy and photothermal therapy to improve on previous shortcomings of the complexes are outlined. Future perspectives of these complexes used in two-photon PDT, photoacoustic imaging and sonotherapy are also discussed. This review covers the literature published from 2017 to 2023.

Risk factors of carbapenemase-producing Enterobacterales acquisition among adult intensive care unit patients at a Kentucky Academic Medical Center

Background

Acquisition of carbapenemase-producing carbapenem-resistant Enterobacterales (CP-CRE) are associated with negative health outcomes. Our adult intensive care unit (ICU) population has experienced low levels of CP-CRE acquisition; however, specific risk factors for this population at our medical facility have not been studied.

Aims

To identify risk factors of CP-CRE acquisition and describe CP-CRE epidemiology among adult ICU patients at our medical facility.

Methods

A retrospective cohort study was performed at a Kentucky Academic Medical Center. Surveillance specimens were collected at admission and weekly thereafter to identify CP-CRE colonization. Clinical data were extracted from patient medical records. Cases were defined as those who tested positive for CP-CRE on ICU admission day 3 or greater. Risk of CP-CRE acquisition was calculated using Modified Poisson regression.

Findings

Independent risk factors of CP-CRE acquisition included administration of enteral tube feeds (risk ratio [RR], 4.46; 95% confidence interval [CI], 1.74-11.43); diagnosis of Clostridioides difficile enterocolitis (RR, 3.51; 95% CI, 1.27-9.68), pressure ulcer (RR, 3.48; 95% CI, 1.91-6.36), and morbid obesity (RR, 2.10; 95% CI, 1.12-3.95); having a drainage tube (RR, 2.63; 95% CI, 1.38-4.98); admission to a medical ICU (RR, 2.39; 95% CI, 1.32-4.35); 90-day use of a carbapenem (RR, 2.27; 95% CI, 1.21-4.26); and dialysis procedure (RR, 2.22; 95% CI, 1.15-4.27).

Conclusion

Most CP-CRE risk factors were associated with alteration of colon microbiota and/or invasive procedures/devices. These results will assist in creating a more targeted CP-CRE active surveillance system and highlight areas for infection prevention intervention.

Risk factors of infection of totally implantable venous access port: A retrospective study

BACKGROUND

Infection is the most frequent complication associated with the use of totally implantable venous access port (TIVAP). This retrospective study was conducted to determine the risk factors affecting TIVAP-related infection.

METHODS

A total of 1406 patients implanted with TIVAP at our center were included in this retrospective study. Incidence of perioperative infection, patient characteristics and bacteriologic data were retrieved and analyzed. Univariable analyses and multiple logistic regression analyses were used to determine the risk factors.

RESULTS

Overall, 72 (5.1%) patients had perioperative infection, and TIVAP was finally removed from 12 (0.85%) patients. There was significantly more hematologic malignancy in the infection group, compared to the non-infection group. Patients with chemotherapy and infection within 30 days before operation also had more infections. There were more inpatients in the infection group than in the non-infection group. The rate of hematoma was higher in the infected patients. Multivariate logistic analysis revealed that hematoma (OR 5.695, p < 0.001), preoperative hospital stay (⩾14d) (OR 2.945, p < 0.001), history of chemotherapy (OR 2.628, p = 0.002), history of infection (within 30 days) (OR 4.325, p < 0.001) were independent risk factor for infection.

CONCLUSIONS

This study demonstrated that hematoma, preoperative hospital stay (⩾14d), history of chemotherapy and history of infection (within 30 days) are independent risk factor for all patients.

The Etiological Bacterial Spectrum of Neck Abscesses of Lymph Node Origin - Gram-Positive and Gram-Negative Bacteria

According to our medical practice as maxillofacial and oral surgeons, operated patients with purulent infections of the cervical lymph nodes are not many in number. On the other hand, the presence of a purulent infection requires not only the surgical evacuation of the pus but also the application of antimicrobial preparations. This necessitates good knowledge of the spectrum of the bacterial causative agents of the disease, the determination and analysis of which is the purpose of this original article. The bacteria studied in 181 patients with a mean age of 26.25 years, ranging between 29 days and 82 years, who underwent surgery for suppurating cervical lymph nodes, were retrospectively analyzed over a period of eight years. No bacteria were found in 69 of them. In 83 (74.11%) of the remaining 112 studied patients, the isolated microorganisms were of the gram-positive spectrum - Staphylococcus aureus (n=34), gram-positive resident microflora represented by more than one bacterial species (n=21), Staphylococcus hemolyticus (n=10), Staphylococcus epidermidis (n=9) and beta-hemolytic streptococci (n=9). Gram-negative bacteria were 25.89% (n=29) - Klebsiella pneumoniae (n=8), Bartonella henselae (n=7), Klebsiella oxytoca (n=6), Enterobacter cloacae (n=5) and Flavimonas oryzihabitans (n=3). No anaerobic and fungal microorganisms were isolated. Therefore, antimicrobial therapy in these patients should be directed against both gram-positive and gram-negative bacteria, which in our study were represented in a ratio of approximately three to one in favor of gram-positive microorganisms. Otherwise, we create a prerequisite for the formation of phlegmon on the neck, which hides real chances for the lives of patients.

Genomic and clinical characteristics of carbapenem-resistant Enterobacter cloacae complex isolates collected in a Chinese tertiary hospital during 2013-2021

Objective

To analyze the molecular epidemiology of carbapenem-resistant Enterobacter cloacae complex (CREC) by whole-genome sequencing and to explore its clinical characteristics.

Methods

Enterobacter cloacae complex isolates collected in a tertiary hospital during 2013-2021 were subjected to whole-genome sequencing to determine the distribution of antimicrobial resistance genes (ARGs), sequence types (STs), and plasmid replicons. A phylogenetic tree of the CREC strains was constructed based on the whole-genome sequences to analyze their relationships. Clinical patient information was collected for risk factor analysis.

Results

Among the 51 CREC strains collected, blaNDM-1 (n = 42, 82.4%) was the main carbapenem-hydrolyzing β-lactamase (CHβL), followed by blaIMP-4 (n = 11, 21.6%). Several other extended-spectrum β-lactamase-encoding genes were also identified, with blaSHV-12 (n = 30, 58.8%) and blaTEM-1B (n = 24, 47.1%) being the predominant ones. Multi-locus sequence typing revealed 25 distinct STs, and ST418 (n = 12, 23.5%) was the predominant clone. Plasmid analysis identified 15 types of plasmid replicons, among which IncHI2 (n = 33, 64.7%) and IncHI2A (n = 33, 64.7%) were the main ones. Risk factor analysis showed that intensive care unit (ICU) admission, autoimmune disease, pulmonary infection, and previous corticosteroid use within 1 month were major risk factors for acquiring CREC. Logistic regression analysis showed that ICU admission was an independent risk factor for CREC acquisition and was closely related with acquiring infection by CREC with ST418.

Conclusion

BlaNDM-1 and blaIMP-4 were the predominant carbapenem resistance genes. ST418 carrying BlaNDM-1 not only was the main clone, but also circulated in the ICU of our hospital during 2019-2021, which highlights the necessity for surveillance of this strain in the ICU. Furthermore, patients with risk factors for CREC acquisition, including ICU admission, autoimmune disease, pulmonary infection, and previous corticosteroid use within 1 month, need to be closely monitored for CREC infection.

Mortality-Related Risk Factors and Novel Antimicrobial Regimens for Carbapenem-Resistant Enterobacteriaceae Infections: A Systematic Review

OBJECTIVE

Carbapenem-resistant Enterobacteriaceae (CRE) has become a significant public health problem in the last decade. We aimed to explore the risk factors of mortality in patients with CRE infections and to focus on the current evidence on antimicrobial regimens for CRE infections, particularly from the perspective of mortality.

METHODS

A systematic literature review was performed by searching the databases of EMBASE, PubMed, and the Cochrane Library to identify studies that evaluated mortality-related risk factors and antimicrobial regimens for CRE infections published from 2012 to 2022.

RESULTS

In total, 33 and 28 studies were included to analyze risk factors and antibiotic treatment, respectively. The risk factors most frequently reported as significantly associated with CRE mortality were antibiotic use (92.9%; 26/28 studies), comorbidities (88.7%; 23/26 studies), and hospital-related factors (82.8%; 24/29 studies). In 10 studies that did not contain ceftazidime/avibactam (CAZ-AVI) therapy, seven demonstrated significantly lower mortality in combination therapy than in monotherapy. However, 5 of 6 studies identified no substantial difference between CAZ-AVI monotherapy and CAZ-AVI combination therapy. Six studies reported substantially lower mortality in CAZ-AVI regimens than in other regimens.

CONCLUSION

Several risk factors, particularly antibiotic use and patients' comorbidities, are strong risk factors for CRE mortality. The optimal regimen for CRE infections remains controversial. Combination therapy should be considered when carbapenems, colistin, tigecycline, or aminoglycosides are administered. CAZ-AVI appears to be a promising antibiotic for CRE infections. Most importantly, treatment should be individualized according to the source and severity of the disease or other highly related risk factors.

Calcium Potentiated Carbapenem Effectiveness Against Resistant Enterobacter Species

BACKGROUND

Antimicrobial resistance (AMR) remains a global health challenge, as bacteria display increasing resistance to last-resort antibiotics such as carbapenems. Enterobacter cloacae are evolving and developing high level of resistance to carbapenems. With increasing AMR, availability of antibiotics for treatment dwindles, hence a need to complement antibiotics to enhance activity or reduce the level of resistance. This study explored the use of calcium ions in attenuating bacterial resistance to carbapenems.

METHOD

E. cloacae strains isolated from hospital fomites and air were subjected to antimicrobial susceptibility testing with carbapenem antibiotics (imipenem, meropenem, doripenem and ertapenem) using the disc diffusion (E. coli ATCC 25922 as control). Growth profile, Ca-Adjusted assay and time-kill curve of the strains was determined in the presence and absence of carbapenem antibiotics following a calcium stress assay.

RESULTS

Growth profile showed that all the E. cloacae strains grew markedly well at 37°C relative to ATCC 25922 and all strains displayed 80% to 100% level of resistance to tested antibiotics. The growth rate of the strains in the presence of the antibiotics was comparable to the growth rate in the absence of carbapenems. Conditional growth stress with calcium ions showed a 50% reduction in the level of resistance with doripenem displaying the lowest level of reduction and ertapenem, the highest.

DISCUSSION

The study showed that E. cloacae strains displayed high levels of resistance to carbapenems, increasing the possibility of treatment failure. Challenging strains with calcium prior to antibiotic treatment led to a significant reduction in level of resistance, indicating that calcium ions could affect bacterial strains during antibiotic activity leading to reduction in level of resistance.

CONCLUSION

Calcium supplement could potentiate carbapenem effectiveness and reduce bacterial AMR.

Co-occurrence of dual carbapenemases KPC-2 and OXA-48 with the mobile colistin resistance gene mcr-9.1 in Enterobacter xiangfangensis

Bacterial infections with the genus Enterobacter are notoriously difficult to treat and often associated with resistance to penicillin, aminoglycosides, fluoroquinolones, and third-generation cephalosporins. Also, Enterobacter species have emerged as the third most common hosts for carbapenemases worldwide, forcing the use of colistin as a “last-resort” antibiotic for the treatment. Studies on the population structure of the genus Enterobacter repeatedly detect E. xiangfangensis as a common clinical species present worldwide. Here, we report on the characteristics of an extreme drug-resistant E. xiangfangensis isolate va18651 (ST88), obtained from a cervical swab of an expectant mother. The isolate was resistant to almost all the classes of antibiotics tested, including β-lactams (viz., penicillins, carbapenems, cephalosporin, monobactams, and their combinations), quinolone, aminoglycosides, and sulfonamide/dihydrofolate reductase inhibitor, and exhibited heteroresistance towards colistin. Analysis of its complete genome sequence revealed 37 antibiotic resistance genes (ARGs), including mcr-9.1, bla_KPC-2, and bla_OXA-48, encoded on three of the four different plasmids (cumulative plasmidome size 604,632 bp). An unusually high number of plasmid-based heavy metal resistance gene (HRG) clusters towards silver, arsenate, cadmium, copper, mercury, and tellurite were also detected. Virulence genes (VGs) for the lipopolysaccharide and capsular polysaccharide structures, iron acquisition (iroBCDEN, ent/fep/fes, sitABCD, iut, and fur), and a type VI secretion system, together with motility genes and Type IV pili, were encoded chromosomally. Thus, a unique combination of chromosomally encoded VGs, together with plasmid-encoded ARGs and HRGs, converged to result in an extreme drug-resistant, pathogenic isolate with survival potential in environmental settings. The use of a disinfectant, octenidine, led to its eradication; however, the existence of a highly antibiotic-resistant isolate with significant virulence potential is a matter of concern in public health settings and warrants further surveillance for extreme drug-resistant Enterobacter isolates.

Molecular Epidemiology, Microbial Virulence, and Resistance of Carbapenem-Resistant Enterobacterales Isolates in a Teaching Hospital in Guangzhou, China

Infection caused by carbapenem-resistant Enterobacterales (CRE) is a global public health problem. We performed whole-genome sequencing to investigate the molecular epidemiological characteristics of local CRE infections and understand the prevalence of hypervirulent carbapenem-resistant Klebsiella pneumoniae (CRKP). Analysis of multiLocus sequence typing (MLST), antibiotic resistance genes, plasmid replicons, virulence genes, and the genetic environment was also performed. Klebsiella pneumoniae (89, 60.95%) was the most common CRE species, primarily prevalent in the intensive care unit (36, 40.45%). Most CRE strains showed a high resistance rate to multiple antibiotics, especially cephalosporins and carbapenems. However, most of these isolates were susceptible to tigecycline (81.7%). Notably, the predominant sequence type (ST) of CRKP isolates was ST11 (80.90%, 72/89), with 93.05% as Klebsiella pneumoniae carbapenemase (KPC)-ST11. In Escherichia coli isolates, ST410 (21.43%, 6/28) was the predominant type, with approximately half carrying bla_NDM-5, and importantly, the ST167 carbapenem-resistant Escherichia coli (CRECO) harbors both New Delhi metallo-β-lactamase (NDM)-5 and KPC-2. In Enterobacter cloacae isolates, three cases of ST88 were carrying the bla_NDM-1 gene, and the ST594 carbapenem-resistant Enterobacter cloacae (CRECC) carrying NDM-1 and KPC-2 has also been identified. In addition, we found three novel STs, ST5386-ST5388. The IncFII (pHN7A8) (98.41%, 62/63) was the most common plasmid replicon type in KPC-2-producing CRKP strains, and the predominant plasmid ST of IncF was [f33:A-:B-] (n = 73). Two CRKP isolates were found to carry 4 virulence genes (iutA, iroB, rmpA, and rmpA2). As concluded, among CRKP strains, ST11 was the predominant ST with bla_KPC-2, and a large proportion of CRKP strains co-harbor bla_KPC-2, bla_SHV, bla_CTX-M, bla_TEB-1B, and fosA. The predominant carbapenemase genes carried by CRECO and CRECC were bla_NDM-1 and bla_CTX-M, respectively.

Comparative resistome and virulome analysis of clinical NDM-1 producing carbapenem-resistant Enterobacter cloacae complex

OBJECTIVES

Enterobacter cloacae complex (ECC), are causatives of hospital-acquired infections (HAI). The antimicrobial resistance (AMR) and virulence and profiling of ECC promotes our knowledge to be further implemented for their elimination in clinical settings.

METHOD

We assembled the whole genome of four clinical Carbapenem-resistant ECC (CR-ECC) and characterized their AMR and virulence profiles using whole genome sequencing (WGS).

RESULTS

The chromosome length of scaled from minimum 3,949,952 bp (for P2) to maximum 4,976,575 bp (for P3). P1 and P2 belonged to ST182. P3 and P4 belonged to ST477 and ST134, respectively. The bla_CTX-M-15 gene was detected in P1 plamsid. P1 and P4 harbored the bla_TEM-1 and bla_OXA-1 genes. bla_NDM-1 was found in P1, P3 and P4. No bla_OXA-48, bla_KPC, bla_VIM and bla_IMP were identified. The plasmids were non-transferrable and had IncFIB, IncFII, Col and IncC incompatibility groups (Inc). Class 1 integron was deteceted in all strains. Genes related to biofilms, adhesins, siderophores (aerobactin, enterobactin and salmochelin), intrinsic antimicrobial efflux pumps, secretory systems type I to VI, environmental and antibiotic stress response regulators, outer membrane proteins (OMPs) and heavy metals (copper, tellurite, arsenic and zinc) resistance were found in the strains. The number of positive virulence factors was higher for P1 to that of other strains.

CONCLUSION

The accumulation of AMR genes in Enterobacter spp. and their high endurance in hostile environments is a serious health problem. More genomic investigations are required in to determine their AMR and virulence genetic reservoirs at the global level.

Carbapenem-resistant Enterobacter cloacae complex in a tertiary Hospital in Northeast China, 2010-2019

Background

Carbapenem-resistant Enterobacter cloacae complex (CREC) is a new emerging threat to global public health. The objective of the study was to investigate the clinical characteristics and molecular epidemiology of CREC infections in the medical center of northeast China.

Methods

Twenty-nine patients were infected/colonized with CREC during a ten-year period (2010–2019) by WHONET analysis. Antibiotic susceptibilities were tested with VITEK 2 and micro broth dilution method (for polymyxin B and tigecycline). Carbapenemase encoding genes, β-lactamase genes, and seven housekeeping genes for MLST were amplified and sequenced for 18 cryopreserved CREC isolates. Maximum likelihood phylogenetic tree was built with the concentrated sequences to show the relatedness between the 18 isolates.

Results

There was a rapid increase in CREC detection rate during the ten-year period, reaching 8.11% in 2018 and 6.48% in 2019. The resistance rate of CREC isolates to imipenem and meropenem were 100.0 and 77.8%, however, they showed high sensitivity to tigecycline, polymyxin B and amikacin. The 30-day crude mortality of CREC infection was 17.4%, indicating that it may be a low-virulence bacterium. Furthermore, molecular epidemiology revealed that ST93 was the predominant sequence type followed by ST171 and ST145, with NDM-1 and NDM-5 as the main carbapenemase-encoding genes. Moreover, E. hormaechei subsp. steigerwaltii and E. hormaechei subsp. oharae were the main species, which showed different resistance patterns.

Conclusion

Rising detection rate of CREC was observed in a tertiary hospital, which showed heterogeneity in drug resistance patterns, resistance genes, and MLST types. Effective infection prevention and control measures should be taken to reduce the spread of CREC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06250-0.