Distribution of virulence genes and genotyping of CTX-M-15-producing Klebsiella pneumoniae isolated from patients with community-acquired urinary tract infection (CA-UTI)

Antibacterial and antibiofilm effects of green synthesized selenium nanoparticles on clinical Klebsiella pneumoniae isolates

Nanotechnology covers many disciplines, including the biological sciences. In this study, selenium nanoparticles (Se-NPs) were synthesized using Artemisia annua extract and investigated against clinical strains of klebsiella pneumoniae (K. pneumoniae) for their anti-biofilm effects. In this experimental study, from May 1998 to September 1998, 50 clinical samples of blood, urine, and sputum were collected, and K. pneumoniae strains were isolated using microbiological methods. Subsequently, the antibacterial effects of Se-NPs at concentrations of 12-25-50-100/5-6/3-25/125 μg/mL were studied. Finally, biofilm-producing strains were isolated, and the expression of mrkA biofilm gene was studied in real-time strains treated with Se-NPs using real-time polymerase chain reaction (PCR). Out of 50 clinical samples, 20 strains of K. pneumoniae were isolated. Minimum inhibitory concentration (MIC) results of Se-NPs showed that Se-NPs were capable of significant cell killing. Real-time PCR results also showed that mrkA gene expression was significantly reduced in strains treated with Se-NPs. According to this study, Se-NPs could reduce bacterial growth and biofilm formation, therefore, could be considered a candidate drug in the medical application for infections caused by K. pneumoniae.

Detection of ESBL and AmpC producing Klebsiella pneumoniae ST11 and ST147 from urinary tract infections in Iran

In the present study a total of 200 Klebsiella pneumoniae isolates were collected from patients with urinary tract infections (UTIs) in Tehran, Iran. Antibiotic resistance was determined by disk diffusion and broth dilution methods. Detection of extended-spectrum β-lactamases (ESBLs) and AmpCs was performed using phenotypic tests. Polymerase chain reaction (PCR) was applied to detect the ESBL, AmpC, and integron genes. Analysis of AmpC and cassette arrays of integron genes was performed using DNA sequencing. Plasmids were analyzed by PCR-based replicon typing and conjugation. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) were applied to explore the genomic relatedness among the isolates. The highest levels of resistance were observed against ampicillin (100%), followed by piperacillin (57.5%), ceftazidime (46%), trimethoprim/sulfamethoxazole (44%), ciprofloxacin (32.5%), and imipenem (19%). Approximately, 66.5% of isolates harbored at least one of the beta-lactamase genes (blaTEM, blaSHV, blaCTX-M, and blaOXA-1). In addition, 22.5% of isolates carried at least one of the AmpC genes including blaDHA and blaCIT. Integron class I was the most prevalent integron among resistant isolates. According to the results of replicon typing, IncFII, IncL/M, and IncA/C were the most frequent replicons, respectively. All selected isolates were able to transfer blaCTX-M, also two isolates transferred the blaDHA-1 gene to Escherichia coli K12 through conjugation. Finally, 21 isolates were categorized into 4 pulsotypes and 11 unique clusters in PFGE. MLST identified ST147 and ST11 sequence types but ST147 was the most prevalent in the current study.

Molecular Characterization of Antibiotic Resistance and Genetic Diversity of Klebsiella pneumoniae Strains

The aims of this study were the molecular characterization of antibiotic resistance and genotyping of Klebsiella pneumoniae strains isolated from clinical cases in Tehran, Iran. A total of 100 different types of clinical human samples were collected from a major teaching hospital in Tehran, Iran. Bacterial isolates were identified using standard microbiological tests. Antimicrobial susceptibility testing was done according to the latest CLSI guidelines. PCR was used to amplify the gyrA gene in quinolone-resistant isolates and sequencing was performed for the detection of probable mutations between the isolates. The occurrence of plasmid-mediated quinolone resistance genes (qnrA, qnrB, and qnrS) was also investigated by PCR. Finally, genotyping of the strains was performed by PFGE in a standard condition. The susceptibility pattern revealed a high and low level of resistance against meropenem (20%) and trimethoprim (37%), respectively. PCR and sequencing detected mutation in the gyrA gene in 51% of quinolone-resistant K. pneumoniae. According to the susceptibility report, among nalidixic acid-resistant strains, 60.5%, 50%, and 42.9% of isolates contained qnrA, qnrB, and qnrS, respectively. Among ciprofloxacin-resistant strains, qnrA was the most frequent PMQR gene. The PFGE differentiated the strains into 31 different genetic clusters so that the highest number (7/66) was in category A. Our results indicated that the frequency of resistance to various antibiotics particularly trimethoprim, nalidixic acid, and cefoxitin are increasing. The presence of qnr (S and A) genes and point mutation of the gyrA gene were likely to be responsible for the resistance toward nalidixic acid and ciprofloxacin in our strains. Also, the results obtained from genotyping indicated that the K. pneumoniae strains isolated in this study belonged to the diverse clones.

Detection of blaKPC and blaNDM carbapenemase genes among Klebsiella pneumoniae isolates in Addis Ababa, Ethiopia: Dominance of blaNDM

Background

Infections caused by Klebsiella pneumoniae have been difficult to control because of the worldwide emergence of carbapenem-resistant isolates mainly due to carbapenemase production. Information regarding carbapenemase-producing K. pneumoniae is still scarce in Ethiopia. Therefore, the current study aimed to determine the prevalence of carbapenemase-producing K. pneumoniae and to assess the occurrence of bla_NDM and bla_KPC carbapenemase genes_.

Methods

A cross-sectional study was conducted from September 2018 to February 2019 at Tikur Anbessa Specialized Hospital, Addis Ababa, Ethiopia. A total of 132 non-duplicate K. pneumoniae isolates were studied. Phenotypic confirmation of carbapenemase production was done by modified Carbapenem Inactivation Method (mCIM). Multiplex PCR was performed for the detection of carbapenemase-encoding genes bla_KPC, and bla_NDM.

Results

Out of the total 132 K. pneumoniae isolates, 39 (29.6%) were non-susceptible to one or more carbapenems. The prevalence of carbapenemase-producing isolates from the total was 28 (21.2%) with mCIM of which the most dominant gene was bla_NDM 26 (92.9%) and one isolate carried bla_KPC concomitantly. Carbapenemase-producing K. pneumoniae isolates were 100% non-susceptible to half of the antimicrobials used in the study, including meropenem and ertapenem. Previous use of carbapenems was associated with carbapenemase production (P = 0.004).

Conclusions

The prevalence of carbapenemase-producing K. pneumoniae isolates was worrying in the study area. To our knowledge, the study described the emergence of bla_NDM and bla_KPC gene carrying K. pneumoniae in Ethiopia for the first time. Further large-scale molecular-based studies, including other carbapenemase genes and sequencing of K. pneumoniae, are warranted to have a clear awareness about the presence of antimicrobial resistance high-risk clones in Ethiopia.

Characterization of virulence factors and antibacterial activity of curcumin in hypervirulent Klebsiella pneumoniae

Aim: Klebsiella pneumoniae is a threat to human health due to its carbapenem-resistance and hypervirulent phenotype. Curcumin is a well-known antimicrobial agent. Hence, it is important to investigate the antivirulence activity of curcumin against hypervirulent K. pneumoniae isolates. Materials & methods: Carbapenemase presence and prevalence of hypervirulent isolates were determined. Inhibition of biofilm formation and expression of virulence genes were analyzed by colorimetry and real-time PCR tests. Results: Sixteen hypervirulent K. pneumoniae isolates were identified. The optimum activity of curcumin was detected at 1/2 minimum inhibitory concentration. Curcumin possessed appropriate antibiofilm, anti-efflux and anticapsule activities. Conclusion: According to the crucial role of biofilm, capsule and efflux systems in the pathogenesis of hypervirulent K. pneumoniae, curcumin may be used to improve anti-Klebsiella treatment.

Virulence factors, antibiotic resistance patterns, and molecular types of clinical isolates of Klebsiella Pneumoniae

BACKGROUND

Klebsiella pneumoniae is armed with a wide range of antibiotic resistance mechanisms that mostly challenge effective treatment. The aims of the current study were to identify the clinical strains of K. pneumoniaealso to determine their phenotypes and molecular characterization related to antimicrobial resistance and virulence genes.

RESEARCH DESIGN AND METHODS

In this investigation, clinical specimens from different hospitals located in Tehran, Iran, were collected during a nine-month period (December 2018 to August 2019). The K. pneumoniae strains were isolated and identified through standard microbial and biochemical assays. Additionally, disk diffusion, combined disk, Modified Hodge Test (MHT) and PCR were performed for antibiotic resistance and virulence gene analysis, respectively.

RESULTS

Eighty-four isolates of K. pneumoniae were subjected to the study. According to the combined disk and modified Hodge test results, 27 (52%) and 15 pathotypes (62.5%) out of resistant strains of isolated K. pneumoniae were detected as ESBL and KPC producers. The virulence genes of mrkD (94%) and magA (11%) were the highest and lowest among isolates, respectively.

CONCLUSIONS

The high prevalence of antibiotic resistance and virulence genes in conjunction with a significant relationship between the strains revealed a high pathogenic capacity of the isolated pathotypes of K. pneumoniae.

Antibiotic resistance, virulence-associated genes analysis and molecular typing of Klebsiella pneumoniae strains recovered from clinical samples

Klebsiella pneumoniae is a multidrug-resistant (MDR) opportunistic pathogen that causes nosocomial infections. Virulence analysis and molecular typing as powerful approaches can provide relevant information on K. pneumoniae infection. In the current study, antibiotic resistance, virulence-associated genes analysis, as well as molecular typing of K. pneumoniae strains were investigated. Out of 505 clinical samples collected from hospitalized patients, 100 K. pneumoniae strains were isolated by standard microbiological methods and subjected to the phenotypic and genotyping analysis. The highest prevalence of resistance was observed against ciprofloxacin (75%), trimethoprim-sulfamethoxazole (73%) and nitrofurantoin (68%). Virulence associated genes including entB, traT, ybts, magA, iucC, htrA and rmpA were found in 80%, 62%, 75%, 5%, 30%, 72% and 48%, of the isolates, respectively. The prevalence of biofilm-associated genes including mrkA, fimH, and mrkD were equally 88% for all tested isolates. Moreover, the efflux pump genes including AcrAB, TolC and mdtK were observed in 41 (41%), 33 (33%) and 26 (26%) of the strains respectively. A significant statistical association was observed between MDR strains and high expression of efflux pump and biofilm genes. The K. pneumoniae strains were differentiated into 11 different genetic patterns using the repetitive element sequence-based PCR (rep-PCR) technique. High prevalence of resistance, presence of various virulence factors, high level of efflux pump, and biofilm gene expression in diverse clones of K. pneumoniae strains pose an important health issue in clinical settings.

Molecular Characteristics of Carbapenem-Resistant Klebsiella pneumoniae Isolates Producing blaVIM, blaNDM, and blaIMP in Clinical Centers in Isfahan, Iran

Background: The emergence and spread of metallo-beta-lactamase (MBL)-producing Klebsiella pneumoniae are growing global public health concerns. One of the most common mechanisms of carbapenem resistance is the production of MBLs, including Verona integron-encoded metallo-beta-lactamase (VIM), New Delhi metallo-beta-lactamase (NDM) and imipenemase (IMP). Objectives: This study aimed to investigate MBLs production among K. pneumoniae isolates. Methods: In this study, 240 K. pneumoniae isolates were collected from clinical samples in three clinical centers of Isfahan, Iran, during February 2017 and November 2018. All isolates were identified using biochemical, microbiological, and molecular methods, and then antimicrobial susceptibility tests were performed to find MBL-producing isolates via phenotypic and genotypic detection methods. Moreover, the minimum inhibitory concentration (MIC) of antibiotics against MBL-positive strains was determined by E-test. Eventually, the clonal relatedness of the MBL-positive strains was analyzed using both multilocus sequence typing (MLST) and rep-PCR. Results: Overall, 33.7% (81/240) of the isolates were resistant to carbapenems, among which 25 (30.8%) were considered MBL-positive. Among 81 strains resistant to carbapenems, genes encoding FimH, rmpA, and mrkD were detected in 87.6% (71/81), 11.1% (9/81), and 67.9% (55/81) of the isolates, respectively. Besides, TEM and SHV as antibiotic resistance genes were detected in 49.3% (40/81) and 80.2% (65/81) of the isolates. But, magA was not detected in any of the tested isolates. The PCR results revealed that blaVIM-1 was the most prevalent gene (13.6%; 11/81), while both blaIMP-1 and blaNDM-1 were only detected in two isolates. Multilocus sequence typing demonstrated that 15 MBL producers belonged to three sequence types (ST): 11 to ST23, two to ST1147, and two to ST15. Finally, rep-PCR typing showed similar fingerprints with MLST, except for ST23, such that ST23 was discriminated in two clonal groups, suggesting the greater discriminatory power of rep-PCR. Conclusions: Here, we reported the emergence of MBL-producing K. pneumoniae in clinical centers of Isfahan, Iran. The findings are alarming and represent the urgent need for the application of infection control programs.

Association between Presence of RmpA, MrkA and MrkD Genes and Antibiotic Resistance in Clinical Klebsiella pneumoniae Isolates from Hospitals in Tehran, Iran

Background:

Klebsiella pneumoniae is an opportunistic pathogen causing nosocomial infection in human. This study aimed to investigate the relationship between the presence of genes involved in biofilm formation in K. pneumoniae isolated from patients and the presence of antibiotic resistance genes.

Methods:

Biochemical tests were used for the identification of K. pneumonia isolated from urine samples referred to hospitals in Tehran, Iran, from Sep 2018 to Jan 2020. The antibiotic resistance pattern was performed and biofilm formation was assessed phenotypically. Finally, β-lactamase genes and adhesion genes were detected by the PCR method.

Results:

We collected 457 K. pneumoniae isolates from hospitals in Tehran, Iran. 110 isolates were resistant to imipenem. Fifty isolates were positive for metallo-β-lactamases that thirty-nine isolates (35.45%) has blaKPC gene, 18 isolates (16.36%) had blaVIM-1 gene and 9 isolates (8.18%) had blaIMP-1 gene detected by PCR. Sixty isolates (54.54%) had strong biofilm, 35 isolates (31.81%) had moderate biofilm and 15 isolates (13.63%) had weak biofilm. The presence of adhesion genes in K. pneumoniae isolates significantly correlated with resistance genes (P<0.001).

Conclusion:

It is clear antibacterial resistance has been significant association with biofilm formation in K. pneumoniae isolates. Therefore, understanding resistance pattern and mechanisms leading to biofilm formation can facilitate efficient treatment of infections caused by K. pneumoniae.

Prevalence of Extended-Spectrum β-Lactamase-Producing Enterobacteriaceae in Ethiopia: A Systematic Review and Meta-Analysis

Background

Antimicrobial resistance especially caused by extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-PE) has become a global public health concern. Globally, these isolates have remained the most important causes of several infections and associated mortality. Their rapid spread in Ethiopia is associated with a lack of regular surveillance and antibiotic stewardship programs. Isolates of ESBL-PE from different regions of Ethiopia were searched exhaustively. However, published data regarding the pooled estimate of ESBL-PE are not conducted in Ethiopia. For this reason, we systematically reviewed laboratory-based studies to summarize the overall pooled prevalence of the isolates recovered from various human specimens.

Methods

An exhaustive literature search was carried out using the major electronic databases including PubMed, Web of Science, MEDLINE, EMBASE, CINAHL, Google Scholar, Cochrane Library, Scopus, and Wiley Online Library to identify potentially relevant studies without date restriction. Original articles which address the research question were identified, screened, and included using the PRISMA follow diagram. Data extraction form was prepared in Microsoft Excel, and data quality was assessed by using 9-point Joanna Briggs Institute critical appraisal tools. Then, data were exported to STATA 16.0 software for analyses of pooled estimation of outcome measures. Estimation of outcome measures at 95% confidence interval was performed using Der-Simonian-Laird's random-effects model. Finally, results were presented via text, figures, and tables.

Results

A comprehensive electronic database literature search has yielded a total of 86 articles. Among the total, 68 original articles were excluded after the review process. A total of 18 studies with 1191 bacterial isolates recovered from 7919 various clinical samples sizes were included for systematic review and meta-analysis. In this study, the pooled prevalence of ESBL-PE was 18% (95% CI: 9–26). Nine out of the total (50%) reviewed articles were studied using the combination disk test. Likewise, E. coli and K. pneumoniae (50% both) were the predominant isolates of ESBL-PE in addition to other isolates such as Salmonella spp. and Shigella spp.

Conclusion

This meta-analysis has shown a low pooled estimate of ESBL-PE in Ethiopia.

The complex genetic region conferring transferable antibiotic resistance in multidrug-resistant and extremely drug-resistant Klebsiella pneumoniae clinical isolates

Antibiotic resistance due to transferable resistance genes is one of the most important concerns in Klebsiella pneumoniae isolated from nosocomial infections. Eighty-eight K. pneumoniae isolates were confirmed through biochemical methods. In addition, antimicrobial susceptibility testing was performed using a disc-diffusion method. Extended-spectrum β-lactamase production among the isolates was screened using a double-disc synergism test, and the resistance genes were identified using PCR. The eight loci for multiple-locus variable number tandem repeat analysis (MLVA) genotyping were selected along with the primers. According to our findings, neomycin (5; 5.6%) and carbapenems (10; 11.3%) showed the most remarkable inhibitory effect but co-trimoxazole (46; 52.2%) was the least effective antibiotic against K. pneumoniae isolates. bla _CTX-M-1 , qnrA, qnrB, qnrS, intI, intII, aac3 and aac6 were detected in 30 (34%), 5 (5.6%), 29 (32.9%), 23 (26.1%), 88 (100%), 72 (81.8%), 26 (29.5%) and 28 (31.8%) of the 88 isolates, respectively. But none of the K. pneumoniae isolates expressed the intIII gene. Using MLVA, 23 MLVA types and eight clusters were identified. Extended-spectrum β-lactamase-producing K. pneumoniae isolates were classified into two clonal complexes. Effective strategies for infection control should be applied to monitor and control the spread of multidrug-resistant isolates by the resistance genes located on the mobile genetic elements.

Prevalence of Potential Virulence Genes in Klebsiella spp. Isolated from Cows with Clinical Mastitis on Large Chinese Dairy Farms

Klebsiella spp. is a common cause of clinical mastitis (CM) in dairy cows. However, relatively less information is available about distribution of virulence factors of Klebsiella spp. isolated from cows with CM. Objectives of this study were, therefore, to determine the prevalence of hypermucoviscosity (HMV) phenotype, capsule serotypes, and potential virulence genes in Klebsiella spp. from cows in China with CM. A total of 241 Klebsiella spp. isolates were recovered from cows with CM on 123 dairy farms (each had >500 lactating cows) located in 13 provinces of China. Of the isolates, 124 (51%) and 117 (49%) were identified as Klebsiella pneumoniae and Klebsiella oxytoca, respectively. The prevalence of HMV was 16% for K. pneumoniae and 11% for K. oxytoca; entB (78%), fimH1 (55%), kfu (31%), and mrkD (24%) were the prevalent virulence genes among K. pneumoniae, whereas entB (50%), fimH1 (30%), and mrkD (22%) were prevalent in K. oxytoca. Prevalence of the lac gene was higher for K. pneumoniae (78%) than for K. oxytoca (13%), whereas the nif gene was more prevalent in K. oxytoca than in K. pneumoniae (12% and 1%, respectively). Fifty-six K. pneumoniae isolates were confirmed as K57, the most prevalent capsule serotype (45%). Twenty-one (18%), 20 (10%), and 9 (8%) of 117 K. oxytoca isolates were positive for K57, K5, and K54 serotypes, respectively. As the predominant serotype, K. pneumoniae K57 isolates had a higher prevalence of the HMV phenotype and fimH1 than non-K57 K. pneumoniae. In conclusion, virulence factors were commonly detected for both K. oxytoca and K. pneumoniae causing CM in Chinese dairy herds. HMV isolates were commonly identified, irrespective of species. In addition, as the predominant capsule in bovine K. pneumoniae, the K57 serotype may be better adapted to the udder environment; therefore, further studies targeting pathogenicity to mammary tissue should contribute new knowledge for vaccine development using this serotype.

Antibiotic resistance, virulence and genetic diversity of Klebsiella pneumoniae in community- and hospital-acquired urinary tract infections in Iran

Klebsiella pneumoniae is among the most important causes of urinary tract infection (UTI). The aim of this study was to investigate the prevalence and correlation of antibiotic resistance with virulence characteristics and genetic diversity in K. pneumoniae isolated from UTIs in Iran. Phenotypic tests and antibiotic susceptibility were carried out on the isolates. Detection of the virulence and extended-spectrum β-lactamase (ESBL) genes was performed by polymerase chain reaction. Pulsed-field gel electrophoresis (PFGE) was used for exploring the genomic relatedness. Hemolysin, biofilm, and hypermucoviscosity formation were observed in 87.1%, 86.4%, and 12.1% of isolates, respectively. The antibiotic resistance rate of K. pneumoniae isolates ranged from 12.1% for meropenem to 100% for amoxicillin. The prevalence of virulence genes ranged from 1.4% for cnf-1 to 100% for mrkD, fimH, kpn, and entB genes. In this study, 91.7%, 33.3%, and 4.2% of phenotypically ESBL-producers were positive for bla_CTX-M, bla_TEM, and bla_SHV genes, respectively. An association was observed between the presence of traT, fyuA, or cnf-1 genes with antibiotic resistance. Two clone types were obtained by PFGE that indicate different K. pneumoniae clones in community- and hospital-acquired UTIs. The findings of this study are valuable in development of treatment strategies against UTIs in Iran.

Virulence factors and clinical patterns of multiple-clone hypermucoviscous KPC-2 producing K. pneumoniae

Carbapenemase-producing Klebsiella pneumoniae (CRKP) are increasingly reported worldwide being necessary the local epidemiological monitoring. Our aim was to characterize the hypermucoviscous CRKP isolates collected in our hospital during a 6 months period. Carriage of the carbapenemase genes (bla KPC, bla NDM, bla VIM and bla OXA-48), extended spectrum β-lactamases (bla SHV-2, bla CTX-M) and the virulence genes (magA, k2A, rmpA, wabG, uge, allS, entB, ycfM, kpn, wcaG, fimH, mrkD, iutA, iroN, hly and cnf-1) were determined by multiplex-PCR. Genetic relationship among the isolates was performed by PFGE and MLST. A total of 35 isolates were recovered, being the urinary and respiratory tract the most common infection sites (34.2%). The bla KPC-2 gene was present in all the isolates, coexisting with bla CTX-M-2 (45.7%), bla SHV-2 (28.6%), and bla CTX-M-2/bla SHV-2 (14.3%). The capsular serotype K2 corresponded with 68.6% of the isolates. Virulence factors frequency were variable [adhesins (97.1%), siderophores (94.3%) and phagocytosis resistance (wabG 48.5%, uge 80% and ycfM 57.1%)]. A total of 10 STs were identified although 40% of them clustered on ST25-CC65, and 17% to ST17. The incidence of KPC-2-producing K. pneumoniae reported by the hospital was 0.290 per 1000 admissions. In summary we described an epidemic scenario of multidrug resistant hypermucoviscous KPC-2 producing ST25 K. pneumoniae in our institution.

Molecular characterization, serotypes and phenotypic and genotypic evaluation of antibiotic resistance of the Klebsiella pneumoniae strains isolated from different types of hospital-acquired infections

Purpose: Virulent and resistant Klebsiella pneumoniae strains are considered as one of the most significant causes of hospital-acquired infections. The present investigation was done to study the distribution of virulence factors, capsule serotypes and phenotypic and genotypic evaluation of antibiotic resistance of the K. pneumoniae strains isolated from hospital-acquired infections.

Patients Materials and methods: Two hundred and sixty different types of hospital-acquired infections were collected and cultured. Antibiotic resistance pattern of K. pneumoniae isolates and their molecular characterization were studied using disk diffusion and PCR, respectively.

Results: One hundred and fifty out of 260 (44.22%) hospital-acquired infections harbored K. pneumoniae. Urine samples (63.75%) had the highest prevalence of K. pneumoniae, while wound (33.33%) had the lowest. K. pneumoniae strains harbored the highest prevalence of resistance against ampicillin (100%), cefuroxime (100%), amoxicillin/clavulanic acid (95.65%) and ceftazidime (95.52%). FimH-1 (93.04%), traT (92.17%), mrkD (84.34%), and entB (80.86%) were the most commonly detected virulence genes. AcrAB (96.52%) and tolC (85.21%) were the most commonly detected antibiotic resistance genes. Prevalence of ompK35 and ompK36 virulence genes were 75.65% and 79.13%, respectively. Prevalence of K1 and K2-positive serotypes were 27.82% and 6.96%, respectively.

Conclusions: High prevalence of resistance against several types of antibiotics and simultaneous presence of some virulence factors and multi-drug resistance genes pose an important public health issue.

Prevalence of extended-spectrum β-lactamase-producing Klebsiella pneumoniae: First systematic review and meta-analysis from Iran

OBJECTIVES

Extended-spectrum β-lactamase-producing Klebsiella pneumoniae (ESBL-KP) have emerged as an important pathogen causing severe infections worldwide. Infections due to ESBL-KP are associated with high morbidity and mortality, especially in developing countries such as Iran. The aim of this study was to assess the pooled prevalence of ESBL-KP with different gene variants in Iran.

METHODS

A literature search of Medline (via PubMed), Embase, Web of Science and Iranian Database was performed. A meta-analysis was conducted using Comprehensive Meta-Analysis Software (version 2.2, Biostat). A fixed- or random-effects model was used based on the heterogeneity test. Publication bias was determined using Begg's rank correlation and Egger's weighted regression methods.

RESULTS

Among 783 articles identified, 43 studies met the eligibility criteria. The pooled prevalence of ESBL-KP was 43.5% (95% CI 39.3-47.9%) among clinical K. pneumoniae isolates. Among genes encoding ESBLs during 2000-2009, SHV, CTX-M and TEM were found with prevalences of 23.3%, 15.2% and 12.3%, respectively, whilst the prevalences of SHV, CTX-M, TEM and VEB were 24%, 28.1%, 25.2% and 8.3%, respectively, during the period 2010-2018.

CONCLUSION

The prevalence of ESBL-KP has increased steadily in recent years among clinical K. pneumoniae isolates in Iran. Thus, initial identification of ESBL-KP according to Clinical and Laboratory Standards Institute (CLSI) guidelines, proper molecular approaches, and implementation of antimicrobial stewardship programmes in Iranian hospitals together with comprehensive infection control measures are urgently needed to control the dissemination of these strains.

Antibiotic resistance, virulence factors and genotyping of Uropathogenic Escherichia coli strains

Background

The way of treating different types of infectious diseases is really important. Using genotyping method, we can determine the genetic relatedness between the organisms with different resistance profile from different sources. The aim of this study was to determine antibiotic resistance and genotyping of uropathogenic Escherichia coli (UPEC) strains using pulsed field gel electrophoresis (PFGE).

Method

Escherichia coli (E. coli) strains were recovered from the patients with urinary tract infections (UTI) whom admitted in several major hospitals in Tehran. Antibiotic susceptibility testing was done according to CLSI guideline. The present of some virulence factor have been detected using PCR assay. Genotyping of the strains was performed by PFGE and all PFGE profiles were subjected to data processing.

Result

In total, 60 E. coli strains were subjected to the study. Most of E. coli isolates were resistant to cefepime (100%) and cephalothin (74%) and susceptible to imipenem (100%), vancomycin (100%) and doxycycline (100%). Among the UPEC isolates the prevalence of fimbriae type I (fimH), hemolysin (hlyA) and aerobactin (aer) genes were 89%, 60% and 90%, respectively. The PFGE differentiated E. coli strains into 33 different genetic clusters. Majority (30%) of them including PFGE type 11 generated 15 bands, while PFGE type 2 was the lowest (2%) prevalent group with 9 bands.

Conclusion

The result showed that the antibiotic resistance is escalating rapidly. UPEC strains causing infections are more likely to harbor certain virulence genes. Our finding also showed E. coli strains isolated under the study were belonged to the diverse clones.

Bacterial CRISPR Regions: General Features and their Potential for Epidemiological Molecular Typing Studies

Introduction

CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) loci as novel and applicable regions in prokaryotic genomes have gained great attraction in the post genomics era.

Methods

These unique regions are diverse in number and sequence composition in different pathogenic bacteria and thereby can be a suitable candidate for molecular epidemiology and genotyping studies. Results:Furthermore, the arrayed structure of CRISPR loci (several unique repeats spaced with the variable sequence) and associated cas genes act as an active prokaryotic immune system against viral replication and conjugative elements. This property can be used as a tool for RNA editing in bioengineering studies.

Conclusion

The aim of this review was to survey some details about the history, nature, and potential applications of CRISPR arrays in both genetic engineering and bacterial genotyping studies.

Role of association of OmpK35 and OmpK36 alteration and blaESBL and/or blaAmpC genes in conferring carbapenem resistance among non-carbapenemase-producing Klebsiella pneumoniae

In Klebsiella pneumoniae, loss of the two major outer membrane porins (OMPs) OmpK35 and OmpK36 confers resistance to carbapenems in strains producing extended-spectrum β-lactamases (ESBLs) or plasmid-mediated AmpC-type β-lactamases. This study investigated mechanisms responsible for carbapenem resistance in non-carbapenemase-producing K. pneumoniae (NCPK). All carbapenem-resistant Enterobacteriaceae (CRE) at Charles Nicolle Hospital (Tunis, Tunisia) were collected over a 6-year period (2010-2015). Among the 334 CRE strains collected, 44 (13.2%) were NCPK. MIC ranges for ertapenem, imipenem and meropenem were 1 to >32 mg/L, 0.125-8 mg/L and 0.125-32 mg/L, respectively. All strains showed a multidrug-resistant (MDR) phenotype and were negative for carbapenemase activity. None of the carbapenemase genes searched for were found. ESBL production was confirmed in all isolates except one [CTX-M-15 (n = 39) and SHV-5 (n = 4)]. Three isolates produce DHA-1 (associated with CTX-M-15 in two strains). Molecular fingerprints grouped the 44 NCPK isolates into seven clusters. In seven representative strains of these clusters, SDS-PAGE results showed that four isolates lacked the OmpK35 porin, one isolate lacked OmpK36 and two isolates lacked both OmpK35 and OmpK36. Sequencing of the corresponding porin genes showed amino acid insertions and deletions leading to early termination of translation, point mutations in the promoter region, or insertion sequences disrupting the gene coding sequence. Loss or deficiency of OMPs, coupled with ESBL and/or AmpC production, plays an important role in conferring carbapenem resistance in K. pneumoniae. Dissemination of these MDR bacteria in our hospital may create serious therapeutic problems in the future.

Frequency of virulence factors in high biofilm formation blaKPC-2 producing Klebsiella pneumoniae strains from hospitals

The aim of this study is to determine the frequency of virulence genes in high biofilm formation bla_KPC-2 producing Klebsiella pneumoniae strains collected over a period of two years. A total of 43 non-repetitive high biofilm bla_KPC-2 producing isolates were screened from 429 strains. The MIC of carbapenems (imipenem and meropenem) ranged from 4 to 32 μg/ml. The OD595 value of the biofilm ranged from 0.56 to 2.56. The K1, K2, K5, K20, K54, K57 genotypes, MLST and virulence factors, including entB, ybtS, mrkD, fimH, rmpA, allS, iutA, kfu, wcaG, aerobaction, fecIRA, shiF, magA and pagO gene, were determined by PCR. The results showed that, among the 43 isolates, 5 of 43 were K1 type, 25 of 43 were K2 type, 4 strains and 2 strains were K5 and K57 respectively. The MLST results showed that 23/43 strains were ST11, followed by ST433(4/43), ST107(4/43), ST690(4/43), ST304(2/43), ST2058(1/43), ST1(1/43), ST146(1/43), ST914(1/43), ST2636(1/43), ST2637(1/43). As to the virulence factors, all 43 strains carried entB, ybtS and mrkD gene, followed by fimH(38/43), rmpA(14/43), allS(34/43), iutA(27/43), kfu(25/43), wcaG(21/43), aerobaction(16/43), fecIRA(15/43), shiF(10/43), magA(5/43) and pagO(5/43). This study demonstrated that high frequency of virulence factors emerging in high biofim bla_KPC-2 producing strains. It also suggested that we should continue to focus on the toxicity variation and it's high time to enhance clinical awareness to the infections causing by Klebsiella pneumoniae.

Molecular Epidemiology and Risk Factors of Carbapenem-Resistant Klebsiella pneumoniae Infections in Eastern China

Background: The increasing prevalence of carbapenem-resistant Klebsiella pneumoniae (CRKP) poses an immediate threat to treatment worldwide. This retrospective study assessed the molecular epidemiology and determined the risk factors for and outcomes of CRKP infections in a general teaching hospital in Shanghai, China.

Methods: From January 2013 to July 2015, 100 consecutive unique CRKP isolates isolated from hospitalized patients were collected. Isolates were screened for antibiotic resistance genes by polymerase chain reaction and molecular typing was performed by pulsed-field gel electrophoresis (PFGE). Patients infected with CRKP comprised the case group and were compared to the control group of patients infected with carbapenem-susceptible Klebsiella pneumoniae. Therapeutic effects were compared in the CRKP infection group.

Results: Among the 100 CRKP isolates, the percentages of multidrug-resistant, extensively drug-resistant (XDR), and pandrug-resistant were 50.0, 50.0, and 0%, respectively. All the CRKP isolates produced KPC-2 and could be divided into 18 PFGE clusters (A–O) and 70 subtypes. No dominant intra-hospital PFGE type was detected using a cutoff of 80% similarity. The ratio of CRKP infection to colonization was 51 to 49. Risk factors correlated with CRKP infection included pulmonary disease (p = 0.038), ICU stay (p = 0.002), invasive ventilation (p = 0.009), blood transfusion (p = 0.028), parenteral nutrition (p = 0.004), sputum suction (p = 0.006), medical history of previous hospitalization (p = 0.022), exposure to antibiotics 90 days before infection (p = 0.030), and antibiotic exposure during hospital stay including carbapenems (p = 0.013), enzyme inhibitors (p = 0.021), nitroimidazoles (p = 0.029), and glycopeptides (p = 0.000). Multivariable analysis showed that sputum suction (odds ratio 3.090, 95% confidence intervals 1.004–9.518, p = 0.049) was an independent risk factor for CRKP infections. Patients infected with CRKP with longer carbapenems treatment course (p = 0.002) showed better outcome.

Conclusion: This study showed the severity of CRKP infection in eastern China. Sputum suction was an independent risk factor for CRKP infection. Prolonged duration of treatment with carbapenems benefited the patients infected with CRKP.

Virulence and Genomic Feature of a Virulent Klebsiella pneumoniae Sequence Type 14 Strain of Serotype K2 Harboring blaNDM-5 in China

The objective of this study was to reveal the molecular mechanism involved in carbapenem resistance and virulence of a K2 Klebsiella pneumoniae clinical isolate 24835. The virulence of the strain was determined by in vitro and in vivo methods. The de novo whole-genome sequencing technology and molecular biology methods were used to analyze the genomic features associated with the carbapenem resistance and virulence of K. pneumoniae 24835. Strain 24835 was highly resistant to carbapenems and belonged to ST14, exhibited hypermucoviscous and unique K2-aerobactin-kfu-rmpA positive phenotype. As the only carbapenemase gene in strain 24835, bla_NDM–5 was located on a 46-kb IncX3 self-transmissible plasmid, which is a very close relation of pNDM-MGR194 from India. Genetic context of bla_NDM–5 in strain 24835 was closely related to those on IncX3 plasmids in various Enterobacteriaceae species in China. The combination of multiple virulence genes may work together to confer the relative higher virulence in K. pneumoniae 24835. Significantly increased resistance to serum killing and mice mortality were found in the virulent New Delhi metallo-β-lactamase (NDM)-producing K. pneumoniae strain compared to the other NDM-producing K. pneumoniae strain. Our study provides basic information of phenotypic and genomic features of K. pneumoniae 24835, a strain displaying carbapenem resistance and relatively high level of virulence. These findings are concerning for the potential of NDM-like genes to disseminate among virulent K. pneumoniae isolates.