Carbapenem-resistant K. Pneumoniae Strains Research Articles

Genetic characteristics of clinical carbapenem-resistant Klebsiella pneumoniae: epidemic ST11 KPC-2-producing strains and non-negligible NDM-5-producing strains with diverse STs

Klebsiella pneumoniae is among the most important Gram-negative pathogens that can cause serious nosocomial infections. The emergence and prevalence of hypervirulent carbapenem-resistant K. pneumoniae (Hv-CRKP) pose a significant challenge to public health. In this study, we characterized thirty carbapenem-resistant K. pneumoniae (CRKP) strains from a tertiary care hospital in Sichuan province, China, by whole-genome sequencing and genome analysis. These strains were all highly resistant to carbapenem but remained susceptible to tigecycline. Of the 30 tested CRKP strains, 23 were positive for blaKPC−2 and seven for blaNDM−5. These blaKPC−2-positive strains all belonged to ST11, while blaNDM−5-positive strains belonged to five distinct STs. Phylogenetic analysis revealed a predominant intra-hospital transmission of ST11-KL64 in KPC-2-producing CRKP, and that both clonal and horizontal transmission of blaNDM−5 have occurred among NDM-5-producing CRKP strains in this hospital. Hypervirulence genes were commonly detected in the CRKP. The prevalent pLVKP-like plasmid and ICEKp seem to have contributed largely to the transmission of virulence genes in them. blaNDM−5 was located on highly similar IncX3 plasmids in the collected strains, and its truncated vision was highlighted. blaKPC−2 was primarily carried by IncFII/IncR plasmids in our collection. At least two IncFII/IncR plasmid subtypes were identified, exhibiting high similarity to many previously reported blaKPC−2-bearing plasmids from different parts of China. The findings provide an expanded knowledge of the genetic characteristics of CRKP, the transmission pattern of carbapenem-resistance genes, and also the convergence of Hv-CRKP.

Hybrid Sequencing-Based Genomic Analysis of Klebsiella pneumoniae from Urinary Tract Infections Among Inpatients at a Tertiary Hospital in Beijing.

Urinary tract infection (UTI) associated with Klebsiella pneumoniae poses a serious threat for inpatients. This study aimed to describe the genomic characteristics of K. pneumoniae causing UTI in a tertiary-care hospital in Beijing, China. A total of 20 K. pneumoniae strains collected from 2020 to 2021 were performed whole-genome sequencing. The Antibiotic susceptibility of 19 common antimicrobial agents was tested against all strains. The multi-locus sequence types (MLSTs) and serotypes were determined from the WGS data. De novo assemblies were used to identify resistance and virulence genes. The presence and characteristics of the plasmids were detected using hybrid assembly of long and short-read data. These K. pneumoniae strains were clustered into nine sequence types (STs) and twelve K-serotypes. All the carbapenem-resistant K. pneumoniae (CRKP) strains acquired carbapenemase blaKPC-2 (n=7). Two CRKP strains exhibited increased resistance to Polymyxin B with MIC ≥ 4 mg/L due to insertion of an IS5-like sequence in the mgrB gene, and they were also involved in a transmission event in Intensive Care Unit. Long-read assemblies identified many plasmids co-carrying multiple replicons. Acquisition of a new IncM2_1 type blaCTX-M-3 positive plasmid was observed after transfer from ICU to neurovascular surgery by comparing the two strains collected from the same patient. K. pneumoniae is a significant pathogen responsible for urinary tract infections. The ST11-KL47 strain, prevalent at our hospital, exhibits a combination of high drug resistance and hypervirulence. It is imperative to enhance ongoing genomic surveillance of urinary tract infection-causing pathogens.

Metagenomics next-generation sequencing (mNGS) reveals emerging infection induced by Klebsiella pneumoniaeniae

ObjectivesThe increasing emergence of hypervirulent Klebsiella pneumoniae (hv-Kp) and carbapenem-resistant K. pneumoniae (CR-Kp) is a serious and substantial public health problem. The use of the last resort antimicrobials, tigecycline and polymyxin to combat infections is complicated by the expanding repertoire of newly-identified CR-hvKp. The transmission and co-occurrence of the corresponding antimicrobial resistance and virulence determinants are largely unknown. The aim of this study was to investigate the dissemination and dynamics of CR-Kp and its antibiotic resistance in a hospitalised patient. MethodsMetagenomic next-generation sequencing (mNGS) was conducted for different specimens collected from an elderly male hospitalised patient. CR-Kp strains were examined using antibiotic susceptibility and string testing. Antimicrobial and virulence genes were annotated using whole-genome sequencing (WGS). ResultsA clinical case of a patient infected with a variety of CR-Kp isolates was reported. The co-occurrence of KPC-2 and NDM-1 in the patient was revealed. The CR-Kp isolates, such as BALF2, and Sputum T1 and T3, were classified into ST11 and ST147, respectively. The genetic signature (iuc operon) of hypervirulence was identified in strain T1, although string testing indicated its intermediate virulence. ConclusionsIn this study, multiple infections of CR-Kp isolates were revealed by mNGS, and their dissemination was attributed to plasmid variations, mgrB inactivation and integrative conjugative elements (ICEs). Furthermore, the finding indicated one likely convergence to form CR-hvKp, different from acquisition of carbapenem-resistance determinants in hvKp. A combination of mNGS and WGS is beneficial for clinical diagnosis and anti-infection therapy, and facilitates a better understanding of genetic variants conferring antimicrobial and virulence properties.

Molecular characteristics of carbapenem-resistant gram-negative bacilli in pediatric patients in China

BackgroundCarbapenem-resistant gram-negative bacilli (CR-GNB) have been increasingly reported in China. However, dynamic monitoring data on molecular epidemiology of CR-GNB are limited in pediatric patients.Results300 CR-GNB isolates (200 Carbapenem-resistant K. pneumoniae (CRKP), 50 carbapenem-resistant A.baumannii (CRAB) and 50 carbapenem-resistant P. aeruginosa (CRPA)) were investigated. The predominant carbapenemase gene was blaNDM−1 (73%) and blaKPC−2 (65%) in neonates and non-neonates. Meanwhile, the predominant STs were ST11 (54%) in neonates and ST17 (27.0%) and ST278 (20.0%) in non-neonates. Notably, a shift in the dominant sequence type of CRKP infections from ST17 /ST278-NDM-1 to ST11-KPC-2 was observed during the years 2017–2021 and KPC-KP showed relatively higher resistance to aminoglycosides and quinolones than NDM-KP.BlaOXA−23 was isolated from all the CRAB isolates while only one isolate expressing blaBIC and 2 isolates expressing blaVIM−2 were found in CRPA isolates. ST195 (22.0%) and ST244 (24.0%) were the most common in CRAB and CRPA isolates and all the STs of CRAB belonged to CC92 while CRPA presents ST types with diversity distribution.ConclusionCRKP showed different molecular phenotypes in neonates and non-neonates and was changing dynamically and high-risk clone of ST11 KPC-KP should be paid more attention. Most CRKP and CRAB strains shared the same CCs, suggesting that intrahospital transmission may occur, and large-scale screening and more effective measures are urgently needed.

High Frequency of blaOXA-48like Producing Klebsiella pneumoniae Isolated from Nosocomial Infection in Azerbaijan, Iran.

Klebsiella pneumoniae is one of the significant agents of hospital-acquired infections. In recent years, carbapenem-resistant K. pneumoniae (CRKP) isolates have been found in numerous epidemics of nosocomial infections. This study aimed to determine carbapenem resistance mechanisms and molecular epidemiological of CRKP infections in Azerbaijan, Iran. A total of 50 non-duplicated CRKP from January 2020 to December 2020 were isolated form Sina and Imam Reza Hospitals in Tabriz, Iran. Antimicrobial susceptibility testing was performed by the disk-diffusion method. The carbapenem resistance mechanisms were determined by the phenotypic and PCR procedures. CRKP isolates were typed by the Random Amplified Polymorphic DNA PCR (RAPD-PCR) technique. Amikacin was the most effective antibiotics against CRKP isolates. AmpC overproduction was observed in five CRKP isolates. Efflux pump activity was found in one isolate by the phenotypic method. Carba NP test could find carbapenemases genes in 96% of isolates. The most common carbapenemases gene in CRKP isolates were blaOXA-48-like (76%) followed by blaNDM (50%), blaIMP (22%), blaVIM (10%), and blaKPC (10%). The outer membrane protein genes (OmpK36 and OmpK35) were identified in 76% and 82% of CRKP isolates, respectively. RAPD-PCR analysis yielded 37 distinct RAPD-types. Most blaOXA-48-like positive CRKP isolates were obtained from patients hospitalized in intensive care unit (ICU) wards with urinary tract infections. The blaOXA-48-like is the main carbapenemase among CRKP isolates in this area. Most blaOXA-48-like producer CRKP strains were collected from the ICU ward and urine samples. To control infections due to CRKP, a strict control program in hospital settings is required.

Carbapenem-Resistant Klebsiella pneumoniae: Diversity, Virulence, and Antimicrobial Resistance.

BackgroundKlebsiella pneumoniae (K. pneumoniae) is one of the most important pathogens in nosocomial infections. It has resistance to most antibiotics, even carbapenem, resulting in restricted therapeutic options.PurposeWe tried to assess the antimicrobial resistance and virulence fitness of carbapenem-resistant K. pneumoniae (CRKP) in addition to their phenotypic and genotypic diversity.Materials and MethodsThe conventional methods, automated Vitek-32 system, and antimicrobial susceptibility pattern were used to detect CRKP isolates. Virulence and resistance genes profiles were created by using PCR technique. The correlation analysis was done by using R-program.ResultsThe antimicrobial resistance profile for all our K. pneumoniae isolates was shocking as the MDR and CRKP were the most prominent phenotypes. Unfortunately, high degrees of heterogeneity among our CRKP isolates were recorded, as 97.5% of them were differentiated into different clusters. We found a negative correlation between the existence of virulence and antimicrobial resistance genes. In contrast to sputum and urine CRPK isolates, the blood isolates showed high antimicrobial resistance and low virulence fitness. Finally, K. pneumoniae creates several outbreaks and crises in Egypt owing to the highly heterogeneity and the wide spread of multidrug-resistant (MDR) and multi-virulent CRKP phenotypes.ConclusionOur results are significant and alarming to health organizations throughout the world for the severity and heterogeneity of K. pneumoniae infections. Therefore, the traditional method for treatment of CRKP infections must be renewed. Additionally, the treatment protocols must be well correlated with the site of infections, phenotypes, and genotypes of CRKP strains.

Molecular epidemiological characteristics of carbapenem-resistant Klebsiella pneumoniae among children in China

Klebsiella pneumoniae infection and antimicrobial resistance among children are major concerns. The occurrence of hypervirulent K. pneumoniae (hvKp) infections is gradually increasing worldwide, and disinfectant resistance is also being reported. Carbapenem- and disinfectant-resistant hvKp infection has made clinical treatment and nosocomial infection control among children increasingly challenging. In this study, whole-genome sequencing was conducted among 34 Carba NP-positive carbapenem-resistant K. pneumoniae (CRKP) strains, and the distribution of antibiotic resistance genes, virulence genes and disinfectant resistance genes was determined. Eleven distinct STs were identified, and most of them were ST11 (58.8%). Among the carbapenem resistance genes, KPC-2 was predominant (61.8%), followed by NDM-1 (26.5%) and IPM-4 (11.8%), and no other carbapenemase genes were found. Twelve virulence genes were investigated. All 34 CRKP strains carried the following virulence genes: rcsA/B, entA, fimA/H and mrkA/D. The gene iucB was present in only 3 (8.9%) CRKP strains. The positive detection rates of the iroN and ybtA genes were 94.1% and 64.7%, respectively. None of the strains was found to carry the rmpA and iroB genes. Two disinfectant resistance genes were investigated in this study. Twenty-one (61.8%) strains carried both the qacE and cepA disinfectant resistance genes, 13 (38.2%) CRKP strains carried only the cepA gene, and no strains with only the qacE gene was detected. The correlations among virulence, drug resistance and disinfectant tolerance showed that the virulence and disinfectant resistance genes were distinct among several types of carbapenemase-producing CRKP strains.

Characteristics of ST11 KPC-2-producing carbapenem-resistant hypervirulent Klebsiella pneumoniae causing nosocomial infection in a Chinese hospital.

BackgroundThe purpose of our study is to analyze the microbiological and clinical characteristics of carbapenem‐resistant hypervirulent Klebsiella pneumoniae (CR‐hvKP) that causes nosocomial infection.MethodsWe collected the carbapenem‐resistant K. pneumoniae (CRKP) strains that caused nosocomial infection in a hospital in China and collected the relevant clinical data. We characterized these strains for their antimicrobial and virulence‐associated phenotype and genotype and analyzed the clonal relatedness. We screened hypervirulent strains and compared them with non‐hypervirulent strains.ResultsWe retrospectively analyzed 62 CRKP strains that caused nosocomial infection in a tertiary hospital within 1 year, of which 41 (41/62, 66.1%) CRKP were considered as CR‐hvKP. All CR‐hvKP strains were multi‐drug resistance (MDR) and the vast majority of isolates (39/41, 95.1%) were ST11 KPC‐2‐producing strains. Two hypermucoviscous isolates and 4 capsular types were found in 41 CR‐hvKP. Twenty‐nine isolates (29/41, 70.7%) showed hypervirulence in Galleria mellonella infection model. PFGE showed that ST11‐KL47 CR‐hvKP and ST11‐KL64 CR‐hvKP exhibited a high degree of clonality, while non‐hypervirulent strains were not significant. CR‐hvKP had higher positive rates of bla KPC‐2 and bla CTX‐M‐65 and higher levofloxacin resistance (p < 0.001, p = 0.005 and p = 0.046, respectively) when compared to the non‐hypervirulent strains. There was no significant difference between the two groups in terms of in‐hospital mortality (7/41, 17.1% vs 5/21, 23.8%, p = 0.743).ConclusionOur research finds that ST11 KPC‐2‐producing CR‐hvKP is the main type of CRKP that caused nosocomial infection, and clonal spread has occurred. We provide more information about CR‐hvKP in health care.

Heteroresistance Is Associated With in vitro Regrowth During Colistin Treatment in Carbapenem-Resistant Klebsiella pneumoniae.

Polymyxins including polymyxin B and colistin (polymyxin E) are considered the last resort for treating infections caused by carbapenem-resistant gram-negative bacteria. However, in vitro regrowth with the emergence of resistance during treatment is common. Polymyxin heteroresistance, particularly in Acinetobacter baumannii and Klebsiella pneumoniae, has been widely reported. This study was primarily performed to evaluate the prevalence of colistin heteroresistance in carbapenem-resistant K. pneumoniae (CR-KP) and the association between in vitro regrowth and heteroresistance. The mechanisms of colistin resistance and the ability of combination therapies to suppress resistance selection were further investigated. A population analysis profile (PAP) analysis showed that 69 (71.9%) of 96 CR-KP strains had colistin heteroresistance. Time-kill assays revealed that the colistin monotherapy could quickly eliminate the bacterial cells in strains without heteroresistance within the first 6 h. Conversely, it could initially reduce the number of cells in heteroresistant strains, but then regrowth occurred rapidly. Resistance screening at 12 and 24 h in the time-kill assays indicated that susceptible populations were killed, and regrowth was the exact result of the continued growth of resistant subpopulations. Colistin resistance in the regrowth subpopulations was mainly due to the overexpression of phoPQ and pmrD. Colistin combined with tetracyclines (tigecycline or minocycline) or aminoglycosides (amikacin or gentamicin) could effectively suppress the resistance selection and significantly elicit in vitro synergistic effects. These findings suggested that the combination therapy can be used to treat infections caused by CR-KP with colistin heteroresistance. Nevertheless, further in vivo studies considering drugs pharmacokinetics/pharmacodynamics are needed to confirm these findings.

Bacterial Epidemiology and Antimicrobial Resistance Profiles in Children Reported by the ISPED Program in China, 2016 to 2020.

ABSTRACTThe Infectious Disease Surveillance of Pediatrics (ISPED) program was established in 2015 to monitor and analyze the trends of bacterial epidemiology and antimicrobial resistance (AMR) in children. Clinical bacterial isolates were collected from 11 tertiary care children’s hospitals in China in 2016 to 2020. Antimicrobial susceptibility testing was carried out using the Kirby-Bauer method or automated systems, with interpretation according to the Clinical and Laboratory Standards Institute 2019 breakpoints. A total of 288,377 isolates were collected, and the top 10 predominant bacteria were Escherichia coli, Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus influenzae, Klebsiella pneumoniae, Moraxella catarrhalis, Streptococcus pyogenes, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Acinetobacter baumannii. In 2020, the coronavirus disease 2019 (COVID-19) pandemic year, we observed a significant reduction in the proportion of respiratory tract samples (from 56.9% to 44.0%). A comparable reduction was also seen in the primary bacteria mainly isolated from respiratory tract samples, including S. pneumoniae, H. influenzae, and S. pyogenes. Multidrug-resistant organisms (MDROs) in children were commonly observed and presented higher rates of drug resistance than sensitive strains. The proportions of carbapenem-resistant K. pneumoniae (CRKP), carbapenem-resistant A. baumannii (CRAB), carbapenem-resistant P. aeruginosa (CRPA), and methicillin-resistant S. aureus (MRSA) strains were 19.7%, 46.4%%, 12.8%, and 35.0%, respectively. The proportions of CRKP, CRAB, and CRPA strains all showed decreasing trends between 2015 and 2020. Carbapenem-resistant Enterobacteriaceae (CRE) and CRPA gradually decreased with age, while CRAB showed the opposite trend with age. Both CRE and CRPA pose potential threats to neonates. MDROs show very high levels of AMR and have become an urgent threat to children, suggesting that effective monitoring of AMR and antimicrobial stewardship among children in China are required.IMPORTANCE AMR, especially that involving multidrug-resistant organisms (MDROs), is recognized as a global threat to human health; AMR renders infections increasingly difficult to treat, constituting an enormous economic burden and producing tremendous negative impacts on patient morbidity and mortality rates. There are many surveillance programs in the world to address AMR profiles and MDRO prevalence in humans. However, published studies evaluating the overall AMR rates or MDRO distributions in children are very limited or are of mixed quality. In this study, we showed the bacterial epidemiology and resistance profiles of primary pathogens in Chinese children from 2016 to 2020 for the first time, analyzed MDRO distributions with time and with age, and described MDROs’ potential threats to children, especially low-immunity neonates. Our study will be very useful to guide antiinfection therapy in Chinese children, as well as worldwide pediatric patients.

In vitro activity of carvacrol in combination with meropenem against carbapenem-resistant Klebsiella pneumoniae.

Carbapenem resistance observed in Klebsiella pneumoniae strains limits treatment options. Therefore, use of antibiotics combined with bioactive compounds may be an important strategy to control K. pneumoniae. The purpose of this study was to evaluate the activity of combination of carvacrol and meropenem on carbapenem-resistant K. pneumoniae (CRKP) strains. The presence of blaOXA-48 carbapenemase in all 25 CRKP strains was identified using the PCR technique. The combination of carvacrol and meropenem was tested for antimicrobial activity on CRKP strains. The minimum inhibitory concentrations of carvacrol and meropenem were detected within a range of 32-128µg/mL using the broth microdilution method. Synergy between carvacrol and meropenem was observed on 8 of the 25 CRKP strains by checkerboard assay (FICI = 0.5) and confirmed by time-kill assay. According to the live-dead test results, the viability percentage of the cells exposed to synergistic combination was 35.47% at the end of 24h. The membrane damage caused by the synergistic combination was spectrophotometrically measured (A = 0.21) and further confirmed by SEM analysis. According to the MTT assay, both carvacrol and meropenem did not show any statistically significant cytotoxic effect on Vero cells (p > 0.05). In conclusion, the results suggest that carvacrol and meropenem can act synergistically to inhibit the growth of CRKP.

Emergence of Ceftazidime/Avibactam and Tigecycline Resistance in Carbapenem-Resistant Klebsiella pneumoniae Due to In-Host Microevolution.

Klebsiella pneumoniae can cause both hospital- and community-acquired clinical infections. Last-line antibiotics against carbapenem-resistant K. pneumoniae (CRKP), such as ceftazidime/avibactam (CZA) and tigecycline (TGC), remain limited as treatment choices. This study aimed to investigate the mechanisms by which CRKP acquires CZA and TGC resistance in vivo under β-lactam antibiotic and TGC exposure. Three CRKP strains (XDX16, XDX31 and XDX51) were consecutively isolated from an inpatient with a urinary tract infection in two months. PFGE and MLST showed that these strains were closely related and belonged to sequence type (ST) 4496, which is a novel ST closely related to ST11. Compared to XDX16 and XDX31, XDX51 developed CZA and TGC resistance. Sequencing showed that double copies of bla KPC-2 were located on a 108 kb IncFII plasmid, increasing bla KPC-2 expression in XDX51. In addition, ramR was interrupted by Insertion sequence (IS) Kpn14 in XDX51, with this strain exhibiting upregulation of ramA, acrA and acrB expression compared with XDX16 and XDX31. Furthermore, LPS analysis suggested that the O-antigen in XDX51 was defective due to ISKpn26 insertion in the rhamnosyl transferase gene wbbL, which slightly reduced TGC susceptibility. In brief, CZA resistance was caused mainly by bla KPC-2 duplication, and TGC resistance was caused by ramR inactivation with additional LPS changes due to IS element insertion in wbbL. Notably, CRKP developed TGC and CZA resistance within one month under TGC and β-lactam treatment without exposure to CZA. The CRKP clone ST4496 has the ability to evolve CZA and TGC resistance rapidly, posing a potential threat to inpatients during antibiotic treatment.

Epidemiology of resistance of carbapenemase-producing Klebsiella pneumoniae to ceftazidime-avibactam in a Chinese hospital.

Aims Klebsiella pneumoniae has been reported to develop increased antibiotic resistance. Ceftazidime‐avibactam (CZA) is a novel antibiotic with activity against serine‐lactamase. Here, we investigated the sensitivity of carbapenem‐resistant K. pneumoniae (CRKP) to CZA and the mechanisms of drug resistance in our hospital.Methods and ResultsPatient characteristics were obtained from medical records. K. pneumoniae and its antibiotic susceptibility were determined using the Vitek‐2 Compact instrument. The antibiotic resistance genes KPC, NDM, OXA‐48, VIM, IMP, CIM, SPM, TMB, SMB, SIM, AIM and DIM were detected using real‐time PCR. Multilocus sequence typing was used for genetic RELATEDNESS analysis. In total, 121 CRKP strains were isolated from patients in the intensive care unit (51·2%), senior ward (12·4%) and neurosurgery department (10%). With an average age of 72·5 years, most patients were in care for respiratory (34·7%), brain (20·7%), digestive tract (13·2%) and cardiovascular (8·3%) diseases. Specimens were predominantly obtained from sputum (39·67%), urine (29·75%) and blood (6·61%).ConclusionOf 23 CZA‐resistant CRKP strains (19·01%), ST11 being the most common at 56·52%, 11 NDM‐1‐positive (47·83%) and four NDM‐5‐positive (17·39%) strains were detected.Significance and Impact of the StudyOur study indicates that CZA resistance occurs in ~19·01% CRKP strains and that bla NDM‐1 and bla NDM‐5 might be critical for resistance.

Mobilization of the nonconjugative virulence plasmid from hypervirulent Klebsiella pneumoniae

BackgroundKlebsiella pneumoniae, as a global priority pathogen, is well known for its capability of acquiring mobile genetic elements that carry resistance and/or virulence genes. Its virulence plasmid, previously deemed nonconjugative and restricted within hypervirulent K. pneumoniae (hvKP), has disseminated into classic K. pneumoniae (cKP), particularly carbapenem-resistant K. pneumoniae (CRKP), which poses alarming challenges to public health. However, the mechanism underlying its transfer from hvKP to CRKP is unclear.MethodsA total of 28 sequence type (ST) 11 bloodstream infection-causing CRKP strains were collected from Ruijin Hospital in Shanghai, China, and used as recipients in conjugation assays. Transconjugants obtained from conjugation assays were confirmed by XbaI and S1 nuclease pulsed-field gel electrophoresis, PCR detection and/or whole-genome sequencing. The plasmid stability of the transconjugants was evaluated by serial culture. Genetically modified strains and constructed mimic virulence plasmids were employed to investigate the mechanisms underlying mobilization. The level of extracellular polysaccharides was measured by mucoviscosity assays and uronic acid quantification. An in silico analysis of 2608 plasmids derived from 814 completely sequenced K. pneumoniae strains available in GenBank was performed to investigate the distribution of putative helper plasmids and mobilizable virulence plasmids.ResultsA nonconjugative virulence plasmid was mobilized by the conjugative plasmid belonging to incompatibility group F (IncF) from the hvKP strain into ST11 CRKP strains under low extracellular polysaccharide-producing conditions or by employing intermediate E. coli strains. The virulence plasmid was mobilized via four modes: transfer alone, cotransfer with the conjugative IncF plasmid, hybrid plasmid formation due to two rounds of single-strand exchanges at specific 28-bp fusion sites or homologous recombination. According to the in silico analysis, 31.8% (242) of the putative helper plasmids and 98.8% (84/85) of the virulence plasmids carry the 28-bp fusion site. All virulence plasmids carry the origin of the transfer site.ConclusionsThe nonconjugative virulence plasmid in ST11 CRKP strains is putatively mobilized from hvKP or E. coli intermediates with the help of conjugative IncF plasmids. Our findings emphasize the importance of raising public awareness of the rapid dissemination of virulence plasmids and the consistent emergence of hypervirulent carbapenem-resistant K. pneumoniae (hv-CRKP) strains.

Mortality-related factors in patients with OXA-48 carbapenemase-producing Klebsiella pneumoniae bacteremia.

Carbapenemase-producing Enterobacterales constitute a serious public health threat; however, information on the oxacilinasa (OXA-48)-type is limited. The objective of the study was to evaluate the risk factors associated with 14-day mortality for patients with bacteremia due to OXA-48 carbapenemase-producing Klebsiella pneumoniae.We conducted a retrospective, single-center observational study of adult patients with K. pneumoniae bacteremia, classifying the strains as carbapenem-susceptible K. pneumoniae (CSKp) and carbapenem-resistant K. pneumoniae (CRKp). All of the CRKp strains were the OXA-48-type.The study included 202 cases of bacteremia: 114 due to CSKp and 88 due to CRKp. The clinical cure rate was higher for the patients with CSKp (85% vs 69% for CSKp and CRKp, respectively; P = .010), while the 14-day mortality rate was lower (13% vs 30%, P = .005). An INCREMENT-CPE score ≥7 (HR 3.05, 95% CI 1.50–6.25, P = .002) was the only independent factor associated with 14-day mortality for the patients with Klebsiella spp. bacteremia. Other factors related to 14-day mortality were a rapidly fatal prognosis (McCabe) (HR 7.1, 95% CI 2.75–18.37, P < .001), dementia (HR 5.9, 95% CI 2.0–7.43, P = .001), and a high-risk source of infection (HR 2.7, 95% CI 1.06–6.82, P = .038).The most important factors associated with 14-day mortality for the patients with K. pneumoniae bacteremia was an INCREMENT-CPE score ≥7, dementia, a McCabe score indicating a rapidly fatal prognosis and a high-risk source of infection. We found no relationship between a poorer outcome and CRKp isolation or inadequate antibiotic therapy.

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

BackgroundKlebsiella 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.MethodsClinical 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).ResultsOf 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.ConclusionsNosocomial 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.

The Emergence of Klebsiella pneumoniae with Reduced Susceptibility Against Third Generation Cephalosporins and Carbapenems in Lagos Hospitals, Nigeria.

This study investigated the prevalence of Klebsiella (K.) pneumoniae isolates among clinical samples of patients in four medical centers in Lagos, Nigeria and the burden of extended-spectrum beta-lactamases (ESBL) and carbapenem-resistant K. pneumoniae (CRKP) strains. Different samples (stool, blood, urine, wound swabs and nasal swabs) from 127 patients with suspected Gram-negative infections based on on-site performed Gram-stain from four public hospitals between March and September 2015 were analyzed. K. pneumoniae was identified in 43 (34%) patients. Resistance rates of these 43 strains according to the CLSI breakpoints were as followed: cotrimoxazole (90.7%), cefuroxime (74.4%), ofloxacin (55.8%), ceftazidime (46.5%), and cefixime (35%). Three isolates (7%) were resistant to imipenem. All isolates were susceptible to amoxicillin/clavulanic acid and nitrofurantoin. The prevalence of ESBL-producing, MDR and CRKP strains was 69.8%, 62.8%, and 7.0%, respectively. Of the ESBL-producing isolates, two K. pneumoniae isolates obtained from urine harbored both blaSHV and blaCTX-M-1, and a third isolate from urine harbored only the blaCTX-M-1. This study revealed the emergence of CRKP isolates and blaCTX-M-1 and blaSHV co-harboring K. pneumoniae strains in Lagos hospitals. The emergence of CRKP strains is an early warning signal for carbapenem antibiotics’ prudent use with concern for their efficacies.

Prevalence, Risk Factors, Treatment Outcome and Molecular Epidemiology of Gastrointestinal Carbapenem-Resistant &lt;i&gt;Klebsiella Pneumoniae&lt;/i&gt; from Infections in China

Background: Carbapenem-resistant K. pneumoniae (CRKP) is the leading cause of hospital infections. The prevalence of CRKP in human and the risk factors that predispose occurrence of CRKP infections need to be determined. Methods: We conducted a retrospective, cross-sectional study of K. pneumoniae strains collected in a hospital in Zhejiang Province, China, from Jan 2014 to Dec 2017. The strains were characterized by antimicrobial susceptibility tests and whole genome sequencing. Then we investigated risk factors of CRKP infections and depicted the likely disease outcomes. Findings: 804 patients tested positive for intestinal CRKP or carbapenem susceptible strains (CSKP) in total. Ninety-seven patients were positive for both intestinal and extra-intestinal CRKP and had significantly (P<0.001) higher percentage of death (12.4%) and discharge against medical advice (DAMA) (27.8%) than those who only harbored intestinal CRKP and intestinal CSKP strains. The virulence factor Yersiniabactin-9 could increase the risk of death and DAMA by 4.6 times (95% CI: 1.8-11.7). Statistically significant risk factors associated with intestinal CRKP infections included the use of urinary catheter (OR=4.8, 95% CI 1.7-13.5), artificial lung ventilation (OR=4.1, 95% CI 2.3-7.3) during the hospitalization and exposure to tigecycline (OR=1.5, 95% CI 1.0-2.3) three months prior to hospital admission. The prevalence rates of human intestinal ST11-K64 CRKP strains has been increasing in the past few years. Interpretation: These data confirm that K. pneumoniae colonization in human gut is a significant risk factor for intestinal infection. Screening for K. pneumoniae colonization upon hospital admission could limit the risk of development of infection in patients and transmission to others in the same ward. Funding: This work was supported by the National Natural Science Foundation of China (No. 81772250, 81861138052) and Research Impact Fund of Hong Kong Research Grants Council (No. 8790002). Declaration of Interest: The authors have declared that no competing interest exists. Ethical Approval: Ethical approval (No. 2020-319) was given by SAHZU.

Nosocomial infection by Klebsiella pneumoniae among neonates: a molecular epidemiological study

Nosocomial infection by Klebsiella pneumoniae (Kp) and drug resistance of Kp among neonates is a major concern. Hypervirulent K.pneumoniae (hvKp) infections are gradually increasing worldwide. Carbapenem-resistant hvKp infection has brought challenges to clinical treatment. To evaluate the changes in drug resistance trends of Kp strains in neonatal intensive care unit (NICU) nosocomial infections, to analyse drug resistance genes and virulence genes of carbapenem-resistant K.pneumoniae (CRKP) and to identify whether these CRKP strains are hvKp. A total of 80 neonates with Kp nosocomial infections from 2013 to 2018 were retrospectively studied. Drug susceptibility testing was performed on 80 Kp strains, among which the 12 CRKP strains were further studied. Kp accounted for 26.9% of nosocomial infections in the NICU. CRKP strains accounted for 15.0%. Among the 80 nosocomial infection Kp strains, CRKP strains accounted for 33.3% and 53.3% in 2017 and 2018 respectively. One of the 12 CRKP strains was positive in the drawing test. The 12 CRKP strains were divided into four complete genome sequence types: cgST1 (N= 2), cgST2 (N= 1), cgST3 (N= 1), and cgST4 (N= 8). Among genes that mediated carbapenem resistance, strains of cgST4 carried NDM-5, strains of cgST2 and cgST3 carried NDM-1, and strains of cgST1 carried IMP-4. None of the 12 CRKP strains carried rmpA/rmpA2 (highly related with hvKp). Nosocomial infections of CRKP among neonates are becoming common, but no hvKp was found among the CRKP strains in this study.

Risk Factors Affecting Clinical Outcome in Patients with Carbapenem-Resistant K. pneumoniae: A Retrospective Study.

BackgroundThe increased prevalence of carbapenem-resistant K. pneumoniae (CRKP) poses a great threat worldwide. Early identification of CRKP in patients is paramount. Moreover, fully understanding the risk factors affecting clinical outcome and actively providing targeted treatment can improve the cure rate of patients with CRKP. Therefore, our study aimed to describe the clinical characteristics and identify the risk factors affecting clinical outcomes in patients with CRKP.Material/MethodsFrom January 2016 to September 2017, CRKP strains and clinical data from 97 hospitalized patients were collected. We first performed an antibiotic susceptibility test on CRKP strains using the Kirby-Bauer disc agar diffusion method. Logistic regression analysis was then performed to analyze risk factors.ResultsAccording to clinical outcome, among the 97 CRKP patients, 67 were in the effective group and 30 patients were in the noneffective group. Risk factors found to correlate with poor clinical outcome in patients with CRKP included ICU admission, arteriovenous catheterization, indwelling gastric tube, indwelling urethral catheter, tracheal intubation, mechanical ventilation, hypoproteinemia, and exposure to carbapenems. Multivariate analysis showed that hypoproteinemia (OR: 2.83, p=0.042), presence of an indwelling gastric tube (OR: 4.54, p=0.005), and exposure to carbapenems (OR: 2.77, p=0.045) negatively affected clinical outcome in patients with CRKP.ConclusionsAdverse risk factors correlated with poor clinical outcomes in patients with CRKP were determined. This could be of help in identifying high-risk patients with whom clinicians should take extra precautions and adjust therapeutic strategy to supplement conventional basic treatment with additional measures.