Allocation of Klebsiella pneumoniae Bloodstream Isolates into Four Distinct Groups by ompK36 Typing in a Taiwanese University Hospital. J Clin Microbiol. 2015;53:3256-3263. [PMID: 26224840 DOI: 10.1128/jcm.01152-15]

Virulence Factors in Klebsiella pneumoniae: A Literature Review

Klebsiella pneumoniae, a member of the autochthonous human gut microbiota, utilizes a variety of virulence factors for survival and pathogenesis. Consequently, it is responsible for several human infections, including urinary tract infections, respiratory tract infections, liver abscess, meningitis, bloodstream infections, and medical device-associated infections. The main studied virulence factors in K. pneumoniae are capsule-associated, fimbriae, siderophores, Klebsiella ferric iron uptake, and the ability to metabolize allantoin. They are crucial for virulence and were associated with specific infections in the mice infection model. Notably, these factors are also prevalent in strains from the same infections in humans. However, the type and quantity of virulence factors may vary between strains, which defines the degree of pathogenicity. In this review, we summarize the main virulence factors investigated in K. pneumoniae from different human infections. We also cover the specific identification genes and their prevalence in K. pneumoniae, especially in hypervirulent strains.

Whole Genome Sequencing of Extended-Spectrum Beta-Lactamase-Producing Klebsiella pneumoniae Isolated from Neonatal Bloodstream Infections at a Neonatal Care Unit, Algeria

Aims: Neonatal bloodstream infections (BSIs) are an important cause of mortality among neonates. Besides, extended-spectrum beta-lactamase-producing Klebsiella pneumoniae (ESBL-Kp) is one of the most frequent pathogens causing neonatal BSIs. This study aimed to characterize ESBL-Kp strains recovered from neonatal BSI and to investigate risk factors associated with ESBL-Kp BSI at the neonatal care unit of Elmeki Hospital, Bejaia, Algeria. Methodology: After isolation, identification, and antibiotic susceptibility testing, the ESBL-Kp strains were characterized by whole genome sequencing. The genomes were then analyzed using bioinformatic tools to determine the resistome, virulome, and phylogenetic relatedness. Results: From September 2019 to May 2020, 27 (8.2%) out of 328 neonates were infected by ESBL-Kp strains. These strains displayed a multidrug-resistant phenotype, and on further investigation, were found to carry an array of antibiotic resistance genes. All ESBL-Kp strains harbored the bla_CTX-M-15 gene. Using in silico multilocus sequence typing analysis, six sequence types (STs) were detected with ST268 being the most frequent (56%, n = 15) indicating a local outbreak, confirmed by single nucleotide polymorphism analysis. The yersiniabactin and colibactin gene clusters were identified in six and two ESBL-Kp strains, respectively. Conclusion: This study showed a high prevalence of CTX-M-15-producing K. pneumoniae strains coharboring different antibiotic resistance mechanisms from neonatal BSIs in Algeria. Screening of health care personnel and mothers for ESBL carriage before delivery, isolation of carriers, barrier precautions, antimicrobial usage, and control of hygiene are needed to prevent the dissemination of these pathogens.

The face of hypervirulent Klebsiella pneumoniae isolated from clinical samples of two Iranian teaching hospitals

Hypervirulent Klebsiella pneumoniae (hvKp) has emerged as a pathogen of global concern. In this study, both phenotypic and genotypic tests were used to detect hvKp. Antimicrobial resistance profiles and clonal relatedness of clinical isolates were also determined. We found that 34.2% (163/477) of the isolates were tellurite resistant, and among them 102 hvKp isolates detected with iucA or iutA or peg-344 as molecular markers. The blaSHV (80.4%), followed by blaCTX-M-15 (76.5%) and blaTEM (67.6%), blaOXA-48 (53.9%), and blaNDM-1 (32.3%) were detected, while blaKPC-1 was not present in any hvKp isolates. It was found that the majority of hvKp isolates belonged to capsular serotype K20 and ompK36 group C, which is related to clonal group (CG) 23 (e.g. ST23). A high percentage of multidrug-resistant hvKp (76.6%) and high resistance to imipenem (67%) indicated a serious problem that should be addressed in the clinical setting.

Characterization of multidrug-resistant and virulent Klebsiella pneumoniae strains belonging to the high-risk clonal group 258 (CG258) isolated from inpatients in northeastern Brazil

Multidrug-resistant (MDR) and hypervirulent Klebsiella pneumoniae (hvKp) clones have become a major threat to global public health. The clonal group 258 (CG258) is considered a high-risk CG and the K. pneumoniae strains belonging to it are often multi-resistant and to spread mainly in the hospital environment. This study aimed to characterize the antimicrobial resistance profile, virulence factors, and the clonal relationships among 13 K. pneumoniae strains belonging to CG258 from patients admitted to a tertiary hospital in Teresina, in the state of Piauí, northeastern Brazil. Ten strains were classified as MDR and three as extensively drug-resistant (XDR). Three different β-lactamase-encoding genes (bla_KPC, bla_OXA-1-like, and bla_CTX-M-Gp1) and six virulence genes (fimH, ycfM, mrkD, entB, ybtS, and kfu) were detected. Moreover, two hypermucoviscous K. pneumoniae strains and one capsular K-type 2 were found. Multilocus sequence typing analysis revealed ten different sequence types (STs) (ST14, ST17, ST20, ST29, ST45, ST101, ST268, ST1800, ST3995, and ST3996) belonging to CG258, being two (ST3995 and ST3996) described for the first time in this study.

Identification of novel vaccine candidates against carbapenem resistant Klebsiella pneumoniae: A systematic reverse proteomic approach

Klebsiella pneumoniae is declared as antibiotic resistant by WHO, with the critical urgency of developing novel antimicrobial therapeutics as drug resistance is the second most dangerous threat after terrorism. Besides many attempts still, there is no effective vaccine available against K. pneumoniae. By utilizing all the available proteomic data we prioritized the novel proteins ideal for vaccine development using bioinformatics tools and techniques. Among the huge data, eight proteins passed all the barriers and were considered ideal candidates for vaccine development. These include: copper silver efflux system outer membrane protein (CusC), outer membrane porin protein (OmpN), Fe⁺⁺ enterobactin transporter substrate binding protein (fepB), zinc transporter substrate binding protein (ZnuA), ribonuclease HI, tellurite resistant methyltransferase (the B), and two uncharacterized hypothetical proteins (WP_002918223 and WP_002892366). These proteins were also subjected to epitope analysis and were found best for developing subunit vaccine against K. pneumoniae. The study shows that the potential vaccine targets are sufficiently efficient being virulent, of outer membranous origin and can be proposed for the DNA third-generation vaccines development that would help to cope up infections caused by multidrug-resistant K. pneumoniae.

Global Evolution of Pathogenic Bacteria With Extensive Use of Fluoroquinolone Agents

It is well-established that the spread of many multidrug-resistant (MDR) bacteria is predominantly clonal. Interestingly the international clones/sequence types (STs) of most pathogens emerged and disseminated during the last three decades. Strong experimental evidence from multiple laboratories indicate that diverse fitness cost associated with high-level resistance to fluoroquinolones contributed to the selection and promotion of the international clones/STs of hospital-associated methicillin-resistant Staphylococcus aureus (HA-MRSA), extended-spectrum β-lactamase-(ESBL)-producing Klebsiella pneumoniae, ESBL-producing Escherichia coli and Clostridioides difficile. The overwhelming part of the literature investigating the epidemiology of the pathogens as a function of fluoroquinolone use remain in concordence with these findings. Moreover, recent in vitro data clearly show the potential of fluoroquinolone exposure to shape the clonal evolution of Salmonella Enteritidis. The success of the international clones/STs in all these species was linked to the strains' unique ability to evolve multiple energetically beneficial gyrase and topoisomerase IV mutations conferring high-level resistance to fluorquinolones and concomittantly permitting the acquisition of an extra resistance gene load without evoking appreciable fitness cost. Furthermore, by analyzing the clonality of multiple species, the review highlights, that in environments under high antibiotic exposure virulence factors play only a subsidiary role in the clonal dynamics of bacteria relative to multidrug-resistance coupled with favorable fitness (greater speed of replication). Though other groups of antibiotics should also be involved in selecting clones of bacterial pathogens the role of fluoroquinolones due to their peculiar fitness effect remains unique. It is suggested that probably no bacteria remain immune to the influence of fluoroquinolones in shaping their evolutionary dynamics. Consequently a more judicious use of fluoroquinolones, attuned to the proportion of international clone/ST isolates among local pathogens, would not only decrease resistance rates against this group of antibiotics but should also ameliorate the overall antibiotic resistance landscape.

Metastatic infection caused by hypervirulent Klebsiella pneumonia and co-infection with Cryptococcus meningitis: A case report

BACKGROUND

Klebsiella pneumoniae (K. pneumoniae) used to affect mainly people with compromised immunity or weakened by other infections, but recent emergence of hypervirulent strains has increased infections even in healthy individuals. These infections include liver abscess, pneumonia, bacteremia, meningitis, necrotizing fasciitis, and endophthalmitis. Although metastatic infection by hypervirulent K. pneumoniae (hvKP) is increasingly recognized, co-infection with Cryptococcus neoformans (C. neoformans) meningitis in immunocompetent hosts is rare but fatal. So, it is necessary to determine the risk factors, complications, and comorbidity of this disease.

CASE SUMMARY

This report describes a 58-year-old man with hvKP pulmonary abscess, bacteremia, and meningitis, accompanied by fatal Cryptococcus meningitis. This patient presented with fever for 1 wk and drowsiness for 3 d. Laboratory findings revealed pulmonary abscess and bacteremia of K. pneumoniae. He was given intravenous antibiotic therapy, and the infection was under control for about 1 wk. However, his condition deteriorated rapidly because of metastatic purulent meningitis. Although hvKP and C. neoformans were isolated and confirmed, the patient died of spontaneous respiratory and cardiac arrest caused by cerebral hernia.

CONCLUSION

HvKP has emerged as a cause of metastatic infections in immunocompetent hosts. polymicrobial co-infections should be taken into consideration when metastatic infection is present.

Evaluation of ompK36 allele groups on clinical characteristics and virulence features of Klebsiella pneumoniae from bacteremia

BACKGROUND/PURPOSE

This study investigated the implications of ompK36 allele groups on clinical and microbiological features of patients with Klebsiella pneumoniae bacteremia.

METHODS

A total of 80 K. pneumoniae bloodstream isolates were collected and then divided into four ompK36 allele groups. Clinical characteristics, bacterial antibiotic resistance and virulence determinants were analyzed, including resistance and virulence genes, hypermucoviscosity phenotype, K capsule serotypes, biofilm formation, serum killing, neutrophil phagocytosis, and mouse lethality studies.

RESULTS

78 isolates were classified into four ompK36 variants, designated groups A (34), B (6), C (26), and D (12), respectively; 2 isolate was untypeable. OmpK36 group C isolates carried higher frequencies of K1/K2 capsule serotypes, hypermucoviscosity phenotype, rmpA gene, allS gene, iroB gene, aerobactin gene, or rmpA2 gene than non-C group isolates. OmpK36 group C isolates were significantly more virulent, as higher serum resistance, higher anti-phagocytosis and higher mouse lethality, than OmpK36 non-C group isolates, except for similar biofilm formation capability. The K20 isolates probably has low expression rates of rmpA and rmpA2 for hypermucoviscosity phenotype. The biofilm formation was significantly associated with ESBL production. OmpK36 group C isolates were more frequently detected in patients with community-acquired bloodstream infection. However, significant underlying diseases and prior use of carbapenem were highly prevalent in patients with OmpK36 non-C group isolates infection. ESBL production was apparently higher in non-C group but did not reach statistical significance.

CONCLUSION

Our results suggest that the OmpK36 group C K.pneumoniae is more associated with community-acquired infection with a lower frequency of underlying illness, but with significantly more virulence in bloodstream infection. This would give a remind that clinicians should be aware of such clinical impacts of the ompK36 allele group.

Molecular characterization and epidemiology of carbapenem non-susceptible Enterobacteriaceae isolated from the Eastern region of Heilongjiang Province, China

Background

The aim of this study was to elucidate the molecular epidemiology of carbapenem non-susceptible Enterobacteriaceae(CNSE) isolated in the Eastern region of Heilongjiang Province, China, and the mechanism of carbapenem resistance.

Methods

A total of 53 CNSE isolates were collected in a grade-3 hospital in Heilongjiang province. Sensitivity to antibiotics was determined using the VITEK-2 Compact automatic system. The modified Hodge test (MHT) and modified carbapenem inactivation test (mCIM) were performed for phenotypic identification. Beta-lactamases gene were detected by Polymerase chain reaction(PCR) and DNA sequencing. The transfer of bla_NDM and bla_KPC was investigated through conjugation experiment. The clinical data of patients were retrospectively reviewed. Homology of Carbapenem-resistant Klebsiella pneumoniae(CRKP) was conducted by multilocus sequence typing (MLST).

Results

CNSE were highly resistant to the majority of antimicrobial agents. The resistance rate was 100% for first, third, fourth generation cephalosporins and enzyme inhibitor compounds. Gentamicin and tobramycin recorded a resistance rate higher than 80%. Less than 30% resistance was detected for amikacin and levofloxacin. Among CNSE 52(98.1%) and 48(90.6%) of CNSE were positive for mCIM and MHT respectively. There were 42 positive bla_KPC genes, three bla_NDM-1 genes, three bla_NDM-5 genes, one bla_NDM-7 gene, and six bla_IMP-4 genes. Most isolates harbored multiple drug resistance gene, especially as related to extended-spectrum-β-lactamases, bla_SHV, bla_TEM and bla_CTX-M-15 genes.The resistant gene was transferred into recipient Escherichia coli J53 through conjugation in 21.3% (10/47) of the strains. MLST revealed that ST76 (n = 36) was the most predominant clone, followed by ST896, ST323 and ST11. A new one ST 2946 was identity by this study.

Conclusion

The carbapenem resistance phenomenon is alarming and bla_KPC-2 is the main resistant gene of CNSE in our hospital. This is the first report of an outbreak caused by bla_KPC-2 positive K. pneumoniae ST76 in the Eastern region of Heilongjiang Province, China. Relevant departments should implement infection control and prevention measures to avoid further dissemination of the multi drug-resistant bacteria (MDR).

A Novel IncA/C1 Group Conjugative Plasmid, Encoding VIM-1 Metallo-Beta-Lactamase, Mediates the Acquisition of Carbapenem Resistance in ST104 Klebsiella pneumoniae Isolates from Neonates in the Intensive Care Unit of V. Monaldi Hospital in Naples

The emergence of carbapenemase producing Enterobacteriaceae has raised major public health concern. The aim of this study was to investigate the molecular epidemiology and the mechanism of carbapenem resistance acquisition of multidrug-resistant Klebsiella pneumoniae isolates from 20 neonates in the neonatal intensive care unit (NICU) of the V. Monaldi Hospital in Naples, Italy, from April 2015 to March 2016. Genotype analysis by pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST) identified PFGE type A and subtypes A1 and A2 in 17, 2, and 1 isolates, respectively, and assigned all isolates to sequence type (ST) 104. K. pneumoniae isolates were resistant to all classes of β-lactams including carbapenems, fosfomycin, gentamicin, and trimethoprim-sulfamethoxazole, but susceptible to quinolones, amikacin, and colistin. Conjugation experiments demonstrated that resistance to third-generation cephems and imipenem could be transferred along with an IncA/C plasmid containing the extended spectrum β-lactamase bla_{SHV -12} and carbapenem-hydrolyzing metallo-β-lactamase bla_{V IM-1} genes. The plasmid that we called pIncAC_KP4898 was 156,252 bp in size and included a typical IncA/C backbone, which was assigned to ST12 and core genome (cg) ST12.1 using the IncA/C plasmid MLST (PMLST) scheme. pIncAC_KP4898 showed a mosaic structure with bla_{V IM-1} into a class I integron, bla_{SHV -12} flanked by IS6 elements, a mercury resistance and a macrolide 2'-phosphotransferase clusters, ant(3″), aph(3″), aacA4, qnrA1, sul1, and dfrA14 conferring resistance to aminoglycosides, quinolones, sulfonamides, and trimethoprim, respectively, several genes predicted to encode transfer functions and proteins involved in DNA transposition. The acquisition of pIncAC_KP4898 carrying bla_{V IM-1} and bla_{SHV -12} contributed to the spread of ST104 K. pneumoniae in the NICU of V. Monaldi Hospital in Naples.

Klebsiella pneumoniae Isolates from Meningitis: Epidemiology, Virulence and Antibiotic Resistance

Klebsiella pneumoniae (KP) resistance to broad-spectrum cephalosporin (BSC) in meningitis is important because of limited therapeutic options. To investigate the antibiotic resistance, virulence and epidemiology of KP in meningitis, we conducted a retrospective study for 33 non-metastatic isolates, including primary meningitis (n = 20) and post-craniotomy meningitis (n = 13) collected from 1999 to 2013. BSC resistance was found in 9 (27.3%) isolates, all from post-craniotomy meningitis, harboring bla _SHV-5 (n = 6), bla _CMY-2 (n = 2), bla _DHA-1 (n = 2), and bla _TEM-1B (n = 1). Positive virulence factors were hypermucoviscosity (n = 22), larger bacterial size (n = 24), virulent capsule serotypes (n = 24, K2, 11; K1, 5; K57, 3; K5, 2; K20, 2 and K54, 1), rmpA (n = 23), rmpA ₂ (n = 20), aerobactin gene (n = 22) and high-grade serum resistance (n = 23, 69.7%). Higher mouse lethality (LD₅₀ < 10⁶) was found in 16 isolates (48.5%). Post-craniotomy isolates were significantly less virulent than primary meningitis isolates, except for similar serum resistance capability. The pulsotype and sequence typing (ST) results were diverse. A minor cluster with pulsotype C and ST23 (n = 5) was identified in primary meningitis isolates. In conclusion, virulence factors and BSC resistance corresponded to about 70% and 30% of KP meningitis isolates respectively. BSC remains appropriate for treating primary meningitis, whereas meropenem is indicated for post-craniotomy meningitis empirically.

Outbreak by Hypermucoviscous Klebsiella pneumoniae ST11 Isolates with Carbapenem Resistance in a Tertiary Hospital in China

Hypervirulent and multidrug resistant Klebsiella pneumoniae strains pose a significant threat to the public health. In the present study, 21 carbapenem-resistant K. pneumoniae isolates (CRKP) were determined by the string test as hypermucoviscous K. pneumoniae (HMKP), with the prevalence of 15.0% (21/140) among CRKP, and 1.1% (21/1838) among all K. pneumoniae isolates. Among them, 7 (33.3%), and 1 (4.76%) isolate belonged to capsular serotype K20 and K2 respectively, while 13 (61.9%, 13/21) weren't successfully typed by capsular serotyping. All the 21 isolates were carbapenemase-producers and were positive for bla_KPC-2. In addition to bla_KPC-2, all the 21 isolates except one harbor bla_SHV-11, and 15 carry extended-spectrum β-lactamase gene bla_CTX-M-65. The virulence-associated genes with more than 90% of positive rates among 21 isolates included ureA (100%, 21/21), wabG (100%, 21/21), fimH (95.2%, 20/21), entB (95.2%, 20/21), ycf (95.2%, 20/21), ybtS (95.2%, 20/21), and iutA (90.5%, 19/21). rmpA and aerobactin were found in 57.1% (12/21) isolates. Five sequence types (STs) were identified by multilocus sequence typing (MLST), including ST11 (11 K-non capsule typable and 5 K20 isolates), ST268 (1 K20 isolate and 1 K-non capsule typable isolate), ST65 (1 K2 isolate), ST692 (1 K-non capsule typable isolate), and ST595, a novel sequence type (1 K-non capsule typable isolate). Pulsed-field gel electrophoresis (PFGE) results showed two major PFGE clusters, of which cluster A accounts for 6 ST11 isolates (28.6%) and cluster B includes 8 ST11 isolates (38.1%, 8/21). Ten and six ST11 isolates were isolated from 2014 and 2015, respectively, while 8 were isolated from the same month of December in 2014. Ten isolates were collected from the intensive care unit (ICU), and all except one belonged to ST11. Additional 4 ST11 isolates were collected from patients in non-ICU wards, who had more than 10 days of ICU stay history in 2014 prior to transfer to their current wards where the isolates were recovered. Taken together, the present study showed a hospital outbreak and dissemination of ST11 HMKP with carbapenem resistance caused by KPC-2. Effective surveillance and strict infection control strategies should be implemented to prevent outbreak by HMKP with carbapenem resistance in hospitals.

Microbiological and Clinical Characteristics of Hypermucoviscous Klebsiella pneumoniae Isolates Associated with Invasive Infections in China

A distinctive syndrome caused by hypermucoviscous Klebsiella pneumoniae (HMKP) including pyogenic liver abscess (PLA) is now becoming a globally emerging disease. In the present study, 22.8% (84/369) of K. pneumoniae clinical isolates associated with various types of invasive infections were identified as HMKP, with 45.2% associated with PLA. Multivariate regression analysis showed that male patients with 41–50 years, PLA, diabetes mellitus, and hypertension were independent risk factors for HMKP infections. K2 (42.9%, 36/84) was the most common capsular serotype among HMKP isolates, followed by K1 (23.8%, 20/84). Seventy-five percentage of K1 HMKP isolates were associated with PLA, while K2 HMKP isolates accounted for more types of invasive infections. The positive rates of iutA, mrkD, aerobactin, iroN, and rmpA among HMKP isolates were significantly higher than those among non-HMKP isolates (p < 0.05). There was a correlation between magA, ybtS, alls, and wcaG and K1 isolates. Interestingly, mrkD was exclusively detected among HMKP (32.1%, 27/84) and K2 isolates (65.9%, 27/41). All K1 and K2 HMKP and non-HMKP isolates were positive for rmpA. Aerobactin was found among 95.0 and 97.5% of K1 and K2 isolates. ST23 was found to be the most prevalent ST among 69 HMKP isolates with K1, K2, K5, K20, and K57 (27.5%, 19/69) and was only found among K1 isolates. ST65 was the second most prevalent ST (26.1%, 18/69) and was also only found among K2 isolates. ST23-K1 HMKP isolates (84.2%, 16/19) were associated with PLA, while ST65-K2 isolates were correlated with more types of infections relative to ST23-K1 isolates. PFGE results showed that the homology of 84 HMKP isolates was diverse. Only five PFGE clusters with more than 75% similarity accounted for more than three isolates. These five PFGE clusters only accounted for 35 (41.7%, 35/84) isolates. In conclusion, our study first found that hypertension and male patients with 41–50 years old were independent risk factors. The composition of ST types and PFGE clusters among K. pneumoniae K2 isolates was more diverse than K1 isolates. K1 and K2 HMKP isolates had respective specific profiles of virulence-associated genes.