Hypermucoviscosity: an extremely sticky phenotype of Klebsiella pneumoniae associated with emerging destructive tissue abscess syndrome

Double trouble: an unusual case of Klebsiella pneumoniae invasive syndrome with liver abscess, gallbladder empyema and infective endocarditis

BACKGROUND

Klebsiella pneumoniae invasive syndrome (KPIS) is characterized by primary pyogenic liver abscess associated with metastatic infections. Although rare, Klebsiella endocarditis carries a high mortality risk.

CASE PRESENTATION

A 60-year-old lady with type II diabetes mellitus presented with fever, malaise, right hypochondriac pain and vomiting for two weeks. Ultrasound abdomen revealed a collection within liver, and distended gallbladder with echogenic debris within. 3 days after ultrasound guided pigtail drainage of gallbladder empyema, newly presence murmur detected. Pus, urine, and blood cultures obtained were positive for Klebsiella pneumonia. Echocardiogram exhibited oscillating mass attached to anterior mitral valve leaflet. After 6 weeks of intravenous ceftriaxone, follow-up echocardiogram and ultrasound showed complete resolution of mitral valve vegetation, hepatic and gallbladder collection.

CONCLUSION

Concomitant extrahepatic infective endocarditis (IE) should raise concerns in daily practice for patients with Klebsiella pneumoniae liver abscesses, despite the rarity of Klebsiella endocarditis. In the absence of diagnostic suspicion, antibiotic treatment regimens may be shortened, and adverse effects from IE infection may ensue.

A unique combination of natural fatty acids from Hermetia illucens fly larvae fat effectively combats virulence factors and biofilms of MDR hypervirulent mucoviscus Klebsiella pneumoniae strains by increasing Lewis acid-base/van der Waals interactions in bacterial wall membranes

Introduction

Hypervirulent Klebsiella pneumoniae (hvKp) and carbapenem-resistant K. pneumoniae (CR-Kp) are rapidly emerging as opportunistic pathogens that have a global impact leading to a significant increase in mortality rates among clinical patients. Anti-virulence strategies that target bacterial behavior, such as adhesion and biofilm formation, have been proposed as alternatives to biocidal antibiotic treatments to reduce the rapid emergence of bacterial resistance. The main objective of this study was to examine the efficacy of fatty acid-enriched extract (AWME3) derived from the fat of Black Soldier Fly larvae (Hermetia illucens) in fighting against biofilms of multi-drug resistant (MDR) and highly virulent Klebsiella pneumoniae (hvKp) pathogens. Additionally, the study also aimed to investigate the potential mechanisms underlying this effect.

Methods

Crystal violet (CV) and ethidium bromide (EtBr) assays show how AWME3 affects the formation of mixed and mature biofilms by the KP ATCC BAA-2473, KPi1627, and KPM9 strains. AWME3 has shown exceptional efficacy in combating the hypermucoviscosity (HMV) virulent factors of KPi1627 and KPM9 strains when tested using the string assay. The rudimentary motility of MDR KPM9 and KP ATCC BAA-2473 strains was detected through swimming, swarming, and twitching assays. The cell wall membrane disturbances induced by AWME3 were detected by light and scanning electron microscopy and further validated by an increase in the bacterial cell wall permeability and Lewis acid-base/van der Waals characteristics of K. pneumoniae strains tested by MATS (microbial adhesion to solvents) method.

Results

After being exposed to 0.5 MIC (0.125 mg/ml) of AWME3, a significant reduction in the rudimentary motility of MDR KPM9 and KP ATCC BAA-2473 strains, whereas the treated bacterial strains exhibited motility between 4.23 ± 0.25 and 4.47 ± 0.25 mm, while the non-treated control groups showed significantly higher motility ranging from 8.5 ± 0.5 to 10.5 ± 0.5 mm.

Conclusion

In conclusion, this study demonstrates the exceptional capability of the natural AWME3 extract enriched with a unique combination of fatty acids to effectively eliminate the biofilms formed by the highly drug-resistant and highly virulent K. pneumoniae (hvKp) pathogens. Our results highlight the opportunity to control and minimize the rapid emergence of bacterial resistance through the treatment using AWME3 of biofilm-associated infections caused by hvKp and CRKp pathogens.

Molecular characterization of hypermucoviscous carbapenemase-encoding Klebsiella pneumoniae isolates from an Egyptian hospital

This study aimed to screen antibiotic resistance and virulence genes in carbapenem-resistant hypermucoviscous Klebsiella pneumoniae isolates from an Egyptian hospital. Among 38 previously confirmed carbapenem-nonsusceptible K. pneumoniae isolates, a string test identified three isolates as positive for hypermucoviscosity. Phenotypic characterization and molecular detection of carbapenemase- and virulence-encoding genes were performed. PCR-based multilocus sequence typing and phylogenetics were used to determine the clonality and global epidemiology of the strains. The coexistence of virulence and resistance genes in the isolates was analyzed statistically using a chi-square test. Three isolates showed the presence of carbapenemase-encoding genes (blaNDM, blaVIM, and blaIMP), adhesion genes (fim-H-1 and mrkD), and siderophore genes (entB); the isolates belonged to sequence types (STs) 101, 1310, and 1626. The relatedness between these sequence types and the sequence types of globally detected hypermucoviscous K. pneumoniae that also harbor carbapenemases was determined. Our analysis showed that the resistance and virulence profiles were not homogenous. Phylogenetically, different clones clustered together. There was no significant association between the presence of resistance and virulence genes in the isolates. There is a need for periodic surveillance of the healthcare settings in Egypt and globally to understand the true epidemiology of carbapenem-resistant, hypermucoviscous K. pneumoniae.

Prognosis and Characteristics of Hypermucoviscous Klebsiella pneumoniae Infection in Critically Ill Patients: A Case Series

Introduction Hypermucoviscous Klebsiella pneumoniae (hvKP) is related to invasive infections; however, there have been very few comprehensive reports on the clinical features and prognosis of critically ill patients with the infection. Methods We conducted a retrospective case series in a general intensive care unit in Japan. Patients with positive blood cultures for KP between January 1, 2020 and December 31, 2022 were included. hvKP was defined by the positivity in the string test. We analyzed the patient's characteristics at baseline, including comorbidities, abscess formation, Sequential Organ Failure Assessment (SOFA) score, Acute Physiology and Chronic Health Evaluation (APACHE) II score, septic shock, duration of hospitalization, 30-day mortality, and infection site. Results A total of 24 patients had a positive blood culture for KP; nine patients (37.5%) were positive for the string test (hvKP) while 15 (62.5%) were negative (non-hvKP). In both groups, the patients were old (mean age, hvKP 80.4 vs. non-hvKP 75.7 years) and more often male (five patients (55.6%) vs. 12 patients (80.0%)). No statistically significant difference was found between the two groups in terms of comorbidities, such as diabetes mellitus, chronic obstructive pulmonary disease, chronic kidney disease, and malignancy. No statistical difference was seen in abscess formation (two patients [22.2%] vs. one patient (6.7%)), SOFA score (5.2±4.8 vs. 4.7±3.4), APACHE II score (19.6 (15.0-20.0) vs. 17.0 (11.2-20.8)), septic shock (five patients (55.6%) vs. four patient (26.7%)), duration of hospitalization (37.2 (12.0-51.0) vs. 32.3 (9.5-21.0)), and 30-day mortality (two patients (22.2%) vs. two patients (13.3%)). Two cases with hvKP died within 24 h. No significant difference was seen in the infection sources; respiratory infection (2 (22.2%) vs. 1 (6.7%)), hepatobiliary infection (2 (22.2%) vs. 7 (46.7%)), and genitourinary infection (1 (11.1%) vs. 5 (33.3%)). Conclusions Critically ill patients with hvKP infection showed characteristics similar to those reported previously. However, the disease could rapidly become severe and have a poor prognostic outcome.

Genomic epidemiology and temperature dependency of hypermucoviscous Klebsiella pneumoniae in Japan

Klebsiella pneumoniae (Kp) has emerged as a global life-threatening pathogen owing to its multidrug resistance and hypervirulence phenotype. Several fatal outbreaks of carbapenem-resistant hypervirulent Kp have been reported recently. Hypermucoviscosity (HMV) is a phenotype commonly associated with hypervirulence of Kp, which is usually regulated by rmpA or rmpA2 (regulators of the mucoid phenotype). Here, we found that temperature was important in the HMV phenotype of Kp, and the impact of temperature on HMV was not uniform among strains. We investigated the HMV phenotype at 37 °C and room temperature (20–25 °C) in 170 clinically isolated hypermucoviscous Kp strains in Japan and analysed the association between the HMV phenotype, virulence genes and antimicrobial resistance (AMR) genes. String length distribution at different temperatures was correlated with the genomic population of Kp. The strains carrying rmpA/rmpA2 frequently showed the HMV phenotype at 37 °C, while the strains negative for these genes tended to show the HMV phenotype at room temperature. Hypervirulent Kp clusters carrying rmpA/rmpA2 without extended-spectrum beta-lactamases (ESBL)/carbapenemases produced higher string lengths at 37 °C than at room temperature, and were mostly isolated from the respiratory tract. Other HMV strains showed distinct characteristics of not carrying rmpA/rmpA2 but were positive for ESBL/carbapenemases, with a higher string length at room temperature than at 37 °C, and were frequently isolated from bloodstream infections. In total, 21 (13.5 %) HMV isolates carried ESBL and carbapenemases, among which five isolates were carbapenem-resistant hypervirulent Kp with a pLVPK-like plasmid (an epidemic virulence plasmid) and a pKPI-6-like plasmid (an epidemic bla_IMP-6-bearing plasmid in Japan), suggesting the convergence of worldwide hypervirulence and epidemic AMR in Japan.

Urinary Tract Infections Caused by K. pneumoniae in Kidney Transplant Recipients – Epidemiology, Virulence and Antibiotic Resistance

Urinary tract infections are the most common complication in kidney transplant recipients, possibly resulting in the deterioration of a long-term kidney allograft function and an increased risk of recipient’s death. K. pneumoniae has emerged as one of the most prevalent etiologic agents in the context of recurrent urinary tract infections, especially with multidrug resistant strains. This paper discusses the epidemiology and risk factors associated with urinary tract infections in kidney transplant recipients, multi-drug resistance of K. pneumoniae (ESBL, KPC, NDM), treatment and pathogenesis of K. pneumoniae infections, and possible causes of recurrent UTIs. It also addresses the issue of colonization/becoming a carrier of K. pneumoniae in the gastrointestinal tract and asymptomatic bacteriuria in relation to a symptomatic UTI development and epidemiology.

Rapid identification of capsulated Acinetobacter baumannii using a density-dependent gradient test

BACKGROUND

Gram-negative bacterial capsules are associated with production of carbohydrates, frequently resulting in a mucoid phenotype. Infections caused by capsulated or mucoid A. baumannii are associated with increased clinical severity. Therefore, it is clinically and epidemiologically important to identify capsulated A. baumannii. Here, we describe a density-dependent gradient test to distinguish between capsulated and thin/non-capsulated A. baumannii.

RESULTS

Thirty-one of 57 A. baumannii isolates displayed a mucoid phenotype. The density-dependent gradient test was comprised of two phases, with silica concentrations of 30% (top phase) and 50% (bottom phase). Twenty-three isolates migrated to the bottom phase, indicating thin or non-capsulated strains, and 34 migrated to the top phase, suggesting strains suspected to be capsulated. There was agreement between the mucoid and the non-mucoid phenotypes and the density-dependent gradient test for all but three isolates. Total carbohydrates extracted from strains suspected to be capsulated were significantly higher. Transmission electron microscopy confirmed the presence of a capsule in the six representative strains suspected to be capsulated.

CONCLUSIONS

The density-dependent gradient test can be used to verify capsule presence in mucoid-appearing A. baumannii strains. Identifying capsulated strains can be useful for directing infection control measures to reduce the spread of hypervirulent strains.

Environmental persistence and disinfectant susceptibility of Klebsiella pneumoniae recovered from pinnipeds stranded on the California Coast

Hypermucoviscous K. pneumoniae (HMV) are emergent zoonotic pathogens associated with increased invasiveness and pathogenicity in terrestrial and marine mammals. In this study, HMV and non-HMV isolates recovered from stranded pinnipeds were used to investigate: 1) their persistence in sea and fresh water microcosms at 10 and 20°C, 2) their capacity to form biofilms, and 3) the biocide efficacy of four disinfectants on their planktonic and biofilm phenotypes. Results indicated that although HMV isolates were significantly more mucoviscous, non-HMV isolates displayed significantly greater capacity to form biofilms (p < 0.05). Additionally, non-HMV isolates persisted in greater numbers in both sea- and freshwater, particularly at 20°C. These two phenomena could be associated with the greater growth observed for non-HMV isolates in in-vitro growth-curve assays (p < 0.05). Similar susceptibility to disinfectants was detected in HMV and non-HMV isolates when exposed for 24 h; however, the minimal biofilm disinfectant eradication concentration for HMV isolates was significantly higher than that for non-HMV when exposed to disinfectants for 0.5 h. This information should be taken into consideration when developing biosecurity protocols in facilities holding marine mammals in captivity.

Genetic diversity and multiple antibiotic resistance index study of bacterial pathogen, Klebsiella pneumoniae strains isolated from diseased Indian major carps

Intensive fish farming systems have led to increase in disease incidence, due to higher stocking density, high organic matter levels, and poor quality of the aquatic environment. Diseased fish samples showing hemorrhages and reddish lesions were collected from different freshwater fish farms located at three different districts of West Bengal, India (Burdwan, North 24 Parganas, and Nadia). The present study was conducted to evaluate the genetic diversity of ten different Klebsiella pneumoniae strains isolated from different infected freshwater fish samples based on 16S rRNA gene sequence analysis. Primarily, Klebsiella-specific media was used for the isolation and characterization of Klebsiella pneumoniae. Further, through a biochemical test, all the strains were confirmed as K. pneumoniae. PCR analysis of 16S-23S internal transcribed spacer (PCR ribotyping) was carried out to study the species variation within different Klebsiella pneumoniae isolates. For all the isolates, a conserved PCR ribotype pattern was observed while differing from other bacterial species. Phylogenetic study showed the high degree of homology with diverse source of other strains. The multiple antibiotic resistance (MAR) values of the present study for the isolates were found to be 0.468. MAR value above 0.2 indicates that the source of isolation was highly contaminated with antibiotics. Based on the 16S rRNA gene sequence analysis, the present study revealed the genetic diversity of Klebsiella pneumoniae isolated from the different diseased fish farms of West Bengal. All the strains were found to be hypermucoviscous and multidrug-resistant, thus making it pathogenic towards the host organisms. Further, the study revealed a high prevalence of K. pneumoniae in aquaculture farms, representing a risk towards successful aquaculture.

Rapidly Fatal Emphysematous Osteomyelitis with Multiple Septic Emboli and Liver Abscess Caused by Klebsiella pneumoniae

Emphysematous osteomyelitis, characterized by intraosseous gas, is a rare but potentially fatal condition that requires prompt diagnosis and aggressive therapy. Causative organisms are members of the bacterial family Enterobacteriaceae or anaerobes in most cases and significant comorbidities such as diabetes mellitus and malignancy, may predispose an individual to the development of emphysematous osteomyelitis. We report a case of extensive emphysematous osteomyelitis via hematogenous spread from Klebsiella pneumoniae liver abscess, complicated by gas-containing abscesses in adjacent soft tissues and epidural space, and multiple systemic septic emboli in a diabetic patient.

Identification of Two Regulators of Virulence That Are Conserved in Klebsiella pneumoniae Classical and Hypervirulent Strains

Klebsiella pneumoniae is widely recognized as a pathogen with a propensity for acquiring antibiotic resistance. It is capable of causing a range of hospital-acquired infections (urinary tract infections [UTI], pneumonia, sepsis) and community-acquired invasive infections. The genetic heterogeneity of K. pneumoniae isolates complicates our ability to understand the virulence of K. pneumoniae. Characterization of virulence factors conserved between strains as well as strain-specific factors will improve our understanding of this important pathogen. The MarR family of regulatory proteins is widely distributed in bacteria and regulates cellular processes such as antibiotic resistance and the expression of virulence factors. Klebsiella encodes numerous MarR-like proteins, and they likely contribute to the ability of K. pneumoniae to respond to and survive under a wide variety of environmental conditions, including those present in the human body. We tested loss-of-function mutations in all the marR homologues in a murine pneumonia model and found that two (kvrA and kvrB) significantly impacted the virulence of K1 and K2 capsule type hypervirulent (hv) strains and that kvrA affected the virulence of a sequence type 258 (ST258) classical strain. In the hv strains, kvrA and kvrB mutants displayed phenotypes associated with reduced capsule production, mucoviscosity, and transcription from galF and manC promoters that drive expression of capsule synthesis genes. In contrast, kvrA and kvrB mutants in the ST258 strain had no effect on capsule gene expression or capsule-related phenotypes. Thus, KvrA and KvrB affect virulence in classical and hv strains but the effect on virulence may not be exclusively due to effects on capsule production.

In addition to having a reputation as the causative agent for hospital-acquired infections as well as community-acquired invasive infections, Klebsiella pneumoniae has gained widespread attention as a pathogen with a propensity for acquiring antibiotic resistance. Due to the rapid emergence of carbapenem resistance among K. pneumoniae strains, a better understanding of virulence mechanisms and identification of new potential drug targets are needed. This study identified two novel regulators (KvrA and KvrB) of virulence in K. pneumoniae and demonstrated that their effect on virulence in invasive strains is likely due in part to effects on capsule production (a major virulence determinant) and hypermucoviscosity. KvrA also impacts the virulence of classical strains but does not appear to affect capsule gene expression in this strain. KvrA and KvrB are conserved among K. pneumoniae strains and thus could regulate capsule expression and virulence in diverse strains regardless of capsule type.

Clinical and microbiological characteristics and occurrence of Klebsiella pneumoniae infection in Japan

Purpose

Klebsiella pneumoniae is a pathogen that causes pneumonia and urinary tract infection. Hypervirulent K. pneumoniae strains often show hypermucoviscosity, are of the K1 or K2 serotype, and harbor the rmpA and magA genes. However, the differences in the prevalence of K. pneumoniae with these hypervirulent characteristics between the infection and colonization status are not well understood. Therefore, in this study, we compared the clinical and microbiological characteristics of K. pneumoniae isolated from urine or sputum samples of cases of infection and colonization.

Patients and methods

This retrospective study was conducted at a tertiary care teaching hospital in Tokyo, Japan. Patients whose sputum or urine tested positive for the presence of K. pneumoniae isolates were randomly included in the study. Clinical and microbiological data were collected from medical records.

Results

Of the 130 cases investigated, 68 and 62 cases showed the presence of K. pneumoniae in the sputum and urine, respectively. There were 49 infection cases, including 21 in the sputum group and 28 in the urine group. The infections were not accompanied by liver abscess. Of the 130 K. pneumoniae isolates, 25 (19.2%) showed capsular serotype K1 or K2, whereas 33 (25.4%) showed hypermucoviscosity. The prevalence of virulence genes magA, allS, rmpA, mrkD, uge, kfu-BC, and wabG was 10% (all in K1), 13.1%, 16.9%, 85.4%, 79.2%, 36.9%, and 91.5%, respectively. In both the sputum and urine groups, there was no difference in the characteristics of patients with infection and those with colonization. Analysis of microbiological characteristics revealed that only rmpA was significantly more frequent in the infection cases than in the colonization/asymptomatic cases in both the sputum and urine groups.

Conclusion

The rmpA-positive K. pneumoniae isolates were dominant in the infection cases compared with those in the colonization/asymptomatic cases, suggesting that rmpA may play a crucial role in the development of urinary tract infection and pneumonia.

First two cases of severe multifocal infections caused by Klebsiella pneumoniae in Switzerland: characterization of an atypical non-K1/K2-serotype strain causing liver abscess and endocarditis

BACKGROUND

We describe the first two multifocal invasive infections due to Klebsiella pneumoniae recently observed in Switzerland.

METHODS

Phenotypic (MIC assays and string test) and molecular analyses (PCR/Sequencing for bla, virulence factor genes and whole genome sequencing for one strain) were performed to characterize the causative K. pneumoniae isolates.

RESULTS

Both K. pneumoniae isolates (Kp1 and Kp2) were pan-susceptible to antibiotics and produced narrow-spectrum SHV β-lactamases. However, only Kp1 was string test positive. Kp1 was of ST380 and caused liver abscess as well as pneumonia and orbital phlegmon in an Eritrean patient. It belonged to the hypervirulent capsular serotype K2 and harboured the classic virulence-associated rmpA and aerobactin genes, fulfilling both the clinical and microbiological definitions for an invasive K. pneumoniae syndrome. Kp2 was of ST1043 and caused both liver abscess and endocarditis in a Swiss patient. Moreover, it did not possess the classic virulence-associated genes. Whole genome sequencing identified less well-known virulence factors in Kp2 that might have contributed to its virulence. Among these there were genes important for intestinal colonization and/or invasion, such as genes involved in adhesion (e.g., fimABCD and mrkABCD), regulation of capsule polysaccharide biosynthesis (e.g., evgS-evgA), as well as iron uptake (iroN), energy conversion, and metabolism.

DISCUSSION

This report confirms the continuous dissemination of hypervirulent K. pneumoniae strains among patients of non-Asian descent in Europe. Moreover, it highlights the genetic background of an atypical hypervirulent K. pneumoniae causing a severe invasive infection despite not possessing the classical virulence characteristics of hypermucoviscous strains.

Association between Virulence Factors and Extended Spectrum Beta-Lactamase Producing Klebsiella pneumoniae Compared to Nonproducing Isolates

Klebsiella pneumoniae is considered an important opportunistic multidrug-resistant pathogen. Extended spectrum β-lactamases (ESBLs) and expression of a multitude of virulence factors may work in a harmony resulting in treatment failure. This study was undertaken to compare the virulence characteristics and genetic relatedness between ESBL and non-ESBL producing K. pneumoniae. Methods. Antibiotic sensitivity test of all isolates was determined by disc diffusion assay. Phenotypic and genotypic detection of ESBL were done. Various virulence factors and some virulence factor-associated genes were screened. Random amplified polymorphic DNA (RAPD) was employed to investigate the genetic fingerprints of ESBL from non-ESBL producing K. pneumoniae. Results. 50% of isolates were ESBL producers. A significant association was observed between ESBL production and biofilm (strong and moderate), serum resistance, and iss gene. Moreover, significant association between non-ESBL producers and hypermucoviscosity was identified. Dendogram analysis of RAPD profile classified K. pneumoniae isolates into four clusters (a, b, c, and d). Seventy-six percent of ESBL producers belonged to cluster a. In conclusion, this study suggests a correlation between ESBL production and some virulence factors. Therefore, success of treatment depends mainly on increased clinicians awareness and enhanced testing by laboratories to reduce the spread of these isolates.

Septicemic invasive Klebsiella pneumoniae infection in a cynomolgus monkey (Macaca fascicularis) with severe diffused suppurative meningoencephalitis

A 2-year-old male cynomolgus monkey (Macaca fascicularis) showed neurological symptoms during quarantine for importation into Japan, and was euthanized due to poor prognosis. Gross anatomical examination revealed a hemorrhagic lesion around the lateral ventricle in the cerebrum. Histologically, severe diffused suppurative meningitis and ventriculitis were detected with numerous Gram-negative bacilli in the cerebrum. Immunohistochemically, the bacilli were positively stained with an antibody against Klebsiella pneumoniae. The bacterium was isolated from the liver, and it was confirmed to be K. pneumoniae by 16S rDNA sequencing. The isolate displayed a hypermucoviscosity phenotype, was positive for the rmpA and k₂A genes, and demonstrated multidrug resistance. These results suggest that invasive K. pneumoniae can cause septicemic infection, characterized by severe diffused suppurative meningoencephalitis in monkeys.

Hypervirulence and hypermucoviscosity: Two different but complementary Klebsiella spp. phenotypes?

Since the hypermucoviscous variants of Klebsiella pneumoniae were first reported, many cases of primary liver abscesses and other invasive infections caused by this pathogen have been described worldwide. Hypermucoviscosity is a phenotypic feature characterized by the formation of a viscous filament ≥5 mm when a bacterial colony is stretched by a bacteriological loop; this is the so-called positive string test. Hypermucoviscosity appears to be associated with this unusual and aggressive type of infection, and therefore, the causal strains are considered hypervirulent. Since these first reports, the terms hypermucoviscosity and hypervirulence have often been used synonymously. However, new evidence has suggested that hypermucoviscosity and hypervirulence are 2 different phenotypes that should not be used synonymously. Moreover, it is important to establish that a negative string test is insufficient in determining whether a strain is or is not hypervirulent. On the other hand, hypervirulence- and hypermucoviscosity-associated genes must be identified, considering that these phenotypes correspond to 2 different phenomena, regardless of whether they can act in synergy under certain circumstances. Therefore, it is essential to quickly identify the genetic determinants behind the hypervirulent phenotype to develop effective methodologies that can diagnose in a prompt and effective way these hypervirulent variants of K. pneumoniae.

Biofilm formation of hypermucoviscous and non-hypermucoviscous Klebsiella pneumoniae recovered from clinically affected African green monkey (Chlorocebus aethiops sabaeus)

In recent years, an emergent Klebsiella pneumoniae hypermucoviscous (HMV) phenotype has been associated with increased invasiveness and pathogenicity in primates. The HMV phenotype is characterized by different capsular serotypes, associated with several genes including the rmpA (regulator of mucoid phenotype) and magA (mucoviscosity-associated) genes. In African green monkeys (AGM) (Chlorocebus aethiops sabaeus) serotypes K1 and K5 have been implicated in fatal multisystemic abscesses. In order to better understand the epizootiology of this pathogen, the capacity of biofilm production of K. pneumoniae isolates presenting the HMV was compared to non-HMV isolates at three different temperatures (25, 30 and 37 °C). The results indicate that HMV and non-HMV isolates display similar capacity to form biofilms at the three different evaluated temperatures. Temperature appears to play a role in the formation of biofilms by K. pneumoniae presenting the HMV phenotype, where larger biofilms were formed at 37 °C than at 25 °C. Knowledge regarding local environmental sources of K. pneumoniae and the possible role of wildlife in the maintenance of this agent in the area is necessary to develop effective recommendations for the prevention and management of this disease in captive AGM populations.

Two unusual cases of successful treatment of hypermucoviscous Klebsiella pneumoniae invasive syndrome

BACKGROUND

A few Japanese cases of hypermucoviscous Klebsiella pneumoniae (K. pneumoniae) invasive syndrome have recently been reported. Although extrahepatic complications from bacteremic dissemination have been observed, infected aneurysms are rare. Furthermore, the primary source of infection is generally a liver abscess, and is rarely the prostate. Therefore, we report two atypical cases of hypermucoviscous K. pneumoniae invasive syndrome.

CASE PRESENTATION

The first case was an 81-year-old Japanese man with no significant medical history, who was referred to our hospital for vision loss in his right eye. Contrast-enhanced whole-body computed tomography revealed abscesses in the liver and the prostate, and an infected left internal iliac artery aneurysm. Contrast-enhanced head magnetic resonance imaging revealed brain abscesses. Cultures of the liver abscess specimen and aqueous humor revealed K. pneumoniae with the hypermucoviscosity phenotype, which carried the magA gene (mucoviscosity-associated gene A) and the rmpA gene (regulator of mucoid phenotype A). We performed enucleation of the right eyeball, percutaneous transhepatic drainage, coil embolization of the aneurysm, and administered a 6-week course of antibiotic treatment. The second case was a 69-year-old Japanese man with diabetes mellitus, who was referred to our hospital with fever, pollakiuria, and pain on urination. Contrast-enhanced whole-body computed tomography revealed lung and prostate abscesses, but no liver abscesses. Contrast-enhanced head magnetic resonance imaging revealed brain abscesses. The sputum, urine, prostate abscess specimen, and aqueous humor cultures revealed K. pneumoniae with the hypermucoviscosity phenotype, which carried magA and rmpA. We performed enucleation of the left eyeball, percutaneous drainage of the prostate abscess, and administered a 5-week course of antibiotic treatment.

CONCLUSIONS

Hypermucoviscous K. pneumoniae can cause infected aneurysms, and the prostate can be the primary site of infection. We suggest that a diagnosis of hvKP invasive syndrome should be considered in all patients who present with K. pneumoniae infection and multiple organ abscesses.

A case of hypermucoviscous Klebsiella pneumoniae liver abscess syndrome in an Iraqi male

A 53-year-old man presented with fevers, productive cough and decreased appetite. He emigrated from Iraq 4 years ago. Chest x-ray revealed a left lung consolidation. Respiratory cultures and two sets of blood cultures grew out pan-susceptible Klebsiella pneumoniae Liver ultrasound revealed a 6.4-cm complex lesion in the left hepatic lobe. A biopsy of the liver lesion produced bloody purulent aspirate; abscess cultures yielded a highly viscous pan-susceptible K. pneumoniae Klebsiella pneumoniae liver abscess syndrome is a newly described invasive syndrome due to a hypermucoviscous phenotype associated with serotypes K1 and K2 of Klebsiella. Although it is more commonly endemic to the Asian-Pacific region, it has been increasingly reported as an emerging global disease. We present the first case of this syndrome in a patient of middle-eastern descent. We also present pictorial evidence of the microbe's unique viscous, muculent texture grown on agar.

Interaction of non-human primate complement and antibodies with hypermucoviscous Klebsiella pneumoniae

Emergent hypermucoviscosity (HMV) phenotypes of Klebsiella pneumoniae have been associated with increased invasiveness and pathogenicity in primates. In this study, we investigated the interaction of African green monkeys (AGM) (Chlorocebus aethiops sabaeus) complement and antibody with HMV and non-HMV isolates as in vitro models of primate infection. Significantly greater survival of HMV isolates was evident after incubation in normal serum or whole blood (p < 0.05) of AGM donors when compared to non-HMV strains. Greater survival of HMV strains (p < 0.05) was found after incubation in whole blood and serum from seropositive donors when compared to seronegative donor samples. Additionally, significantly greater amounts of K. pneumoniae were phagocytozed by AGM leukocytes when complement was active (p < 0.05), but no difference in uptake was observed when serum from seropositive or seronegative animals was used in challenged cells utilizing flow cytometry. Results demonstrate that interaction of cellular and humoral immune elements play a role in the in vitro killing of K. pneumoniae, particularly HMV isolates. Neither AGM serum, nor washed whole blood effectively killed HMV isolates; however, assays using heparinized whole blood of seronegative donors significantly reduced viability of HMV and non-HMV strains. The lack of bacterial killing observed in seropositive donors treatments could be at least partially associated with low IgG2 present in these animals. A better understanding of the pathogenesis of klebsiellosis in primates and host immune response is necessary to identify surface molecules that can induce both opsonizing and bactericidal antibody facilitating killing of Klebsiella, and the development of vaccines in human and animals.

Vaccination with Klebsiella pneumoniae-derived extracellular vesicles protects against bacteria-induced lethality via both humoral and cellular immunity

The emergence of multidrug-resistant Klebsiella pneumoniae highlights the need to develop preventive measures to ameliorate Klebsiella infections. Bacteria-derived extracellular vesicles (EVs) are spherical nanometer-sized proteolipids enriched with outer membrane proteins. Gram-negative bacteria-derived EVs have gained interest for use as nonliving complex vaccines. In the present study, we evaluated whether K. pneumoniae-derived EVs confer protection against bacteria-induced lethality. K. pneumoniae-derived EVs isolated from in vitro bacterial culture supernatants induced innate immunity, including the upregulation of co-stimulatory molecule expression and proinflammatory mediator production. EV vaccination via the intraperitoneal route elicited EV-reactive antibodies and interferon-gamma-producing T-cell responses. Three vaccinations with the EVs prevented bacteria-induced lethality. As verified by sera and splenocytes adoptive transfer, the protective effect of EV vaccination was dependent on both humoral and cellular immunity. Taken together, these findings suggest that K. pneumoniae-derived EVs are a novel vaccine candidate against K. pneumoniae infections.

Clinical and molecular characteristics of multi-clone carbapenem-resistant hypervirulent (hypermucoviscous) Klebsiella pneumoniae isolates in a tertiary hospital in Beijing, China

OBJECTIVES

To provide the clinical and molecular characteristics of carbapenem-resistant hypervirulent (hypermucoviscous) Klebsiella pneumoniae (cr-hvKP) in a tertiary hospital in Beijing, China.

METHODS

The clinical characteristics of four patients with cr-hvKP isolates and 29 patients with carbapenem-resistant classic K. pneumoniae (cr-cKP) infections were analyzed retrospectively. The molecular characteristics of cr-hvKP and cr-cKP isolates were compared.

RESULTS

The KPC-2 gene was detected in all cr-hvKPs except for cr-hvKP6. The cr-hvKPs belonged to three sequence types (STs; ST25, ST65, and ST11), with three pulsed-field gel electrophoresis patterns (I, II, and III) and two capsular serotypes (K2 and non-typeable). Although cr-hvKP1-7 did not cause invasive clinical syndromes such as community-acquired liver abscess with or without extrahepatic complications, they were all nosocomially acquired; cr-hvKP1-5 were clones disseminated between patients A and B. Compared with cr-cKPs, pLVPK-related loci, repA, iroN, and K2 capsular serotype were more prevalent in cr-hvKPs, although no significant difference was found in clinical characteristics between patients with cr-hvKP and cr-cKP infection.

CONCLUSIONS

The hypervirulent ST65 and ST25K. pneumoniae, along with carbapenem-resistant clonal populations ST11, appear to have evolved into cr-hvKP strains. The evidence of bi-directional evolution and emergence of hospital-acquired multi-clone cr-hvKP indicates a confluence of virulence and carbapenem resistance, which might pose major problems in the management of K. pneumoniae infection.

Comparison of the clinical characteristics and outcomes of Klebsiella pneumoniae and Streptococcus pneumoniae meningitis

This multicenter, retrospective cohort study compared the clinical characteristics and outcomes of community-acquired Klebsiella pneumoniae meningitis (CA-KPM) with those of community-acquired Streptococcus pneumoniae meningitis (CA-SPM). Eighty-three adult patients, 27 with CA-KPM and 56 with CA-SPM, were included. Diabetes mellitus (48.1% versus 21.4%; P=0.01) and liver cirrhosis (22.2% versus 5.4%; P=0.05) were more commonly associated with CA-KPM. Comatose mental status (40.7% versus 12.5%; P=0.01), septic shock (44.4% versus 8.9%; P<0.001), and concomitant extrameningeal infections (40.7% versus 7.1%; P=0.001) were also more common in the CA-KPM group. The 28-day mortality (44.4% versus 10.7%; P<0.001) and inhospital mortality (51.9% versus 14.3%; P<0.001) were higher in the CA-KPM group. In conclusion, diabetes mellitus and liver cirrhosis are more common in the CA-KPM patients who were also more likely to present with severe manifestations and poor outcomes.

Resistance of Klebsiella pneumoniae to the innate immune system of African green monkeys

In recent years, an emergent Klebsiella pneumoniae hypermucoviscosity (HMV) phenotype has been associated with increased invasiveness and pathogenicity in primates. In this project, bacteria recovered from infected African green monkeys (AGM) (Chlorocebus aethiops sabaeus) were screened for HMV phenotype, and were compared to non-HMV isolates in in vitro, serum, and oxidative-mediated killing assays. Complement-mediated killing was assessed utilizing freshly collected serum from healthy AGM. Oxidative-mediated killing was investigated utilizing sodium hypochlorite and hydrogen peroxide. Compared to non-HMV isolates, HMV isolates were more resistant to serum-mediated and oxidative killing (p<0.05). Phagocytosis resistance was evaluated using AGM peripheral blood monocytes (PBMC), and results indicated that non-HMV isolates associated with the AGM PBMC to a greater extent than HMV isolates (p<0.001). Measurement of lactate dehydrogenase release showed that HMV isolates were more cytotoxic to AGM PBMC than non-HMV isolates (p<0.001). Thus, the hypermucoid phenotype appears to be an important virulence factor that promotes evasion of innate immune defenses.

Necrotizing fasciitis caused by hypermucoviscous Klebsiella pneumoniae in a Filipino female in North America

Necrotizing fasciitis caused by Klebsiella pneumoniae has been described in Southeast Asia, but has only recently begun to emerge in North America. The hypermucoviscous strain of K. pneumoniae is a particularly virulent strain known to cause devastatingly invasive infections, including necrotizing fasciitis. Here we present the first known case of necrotizing fasciitis caused by hypermucoviscous K. pneumoniae in North America.

Klebsiella: a long way to go towards understanding this enigmatic jet-setter

Klebsiella pneumoniae is the causative agent of a variety of diseases, including pneumonia, urinary tract infections, septicemia, and the recently recognized pyogenic liver abscesses (PLA). Renewed efforts to identify and understand the bacterial determinants required to cause disease have come about because of the worldwide increase in the isolation of strains resistant to a broad spectrum of antibiotics. The recent increased isolation of carbapenem-resistant strains further reduces the available treatment options. The rapid geographic spread of the resistant isolates and the spread to other pathogens are of particular concern. For many years, the best characterized virulence determinants were capsule, lipopolysaccharide, siderophores, and types 1 and 3 fimbriae. Recent efforts to expand this list include in vivo screens and whole-genome sequencing. However, we still know little about how this bacterium is able to cause disease. Some recent clonal analyses of K. pneumoniae strains indicate that there are distinct clonal groups, some of which may be associated with specific disease syndromes. However, what makes one clonal group more virulent and what changes the disease pattern are not yet clear and remain important questions for the future.

Molecular epidemiology and virulence factors of pyogenic liver abscess causing Klebsiella pneumoniae in China

The molecular epidemiology and prevalence of virulence factors of isolates from patients with Klebsiella pneumoniae liver abscess (KLA) in mainland China are unknown. Klebsiella pneumoniae isolates were obtained from drainage samples aseptically collected from patients with pyogenic liver abscess (PLA). The genetic similarity of KLA isolates was analyzed by pulsed-field gel electrophoresis. The hypermucoviscosity (HV) phenotype was identified by a positive string test. The K1 and K2 genotypes, the pLVPK-derived genetic loci, aerobactin gene, kfu and alls were detected by PCR amplification. The sequence types (STs) were identified by multilocus sequence typing. Among the 51 non-repetitive KLA isolates, 49 PFGE types have been identified. In total, 19 (37.2%) and 14 (27.4%) of the 51 KLA isolates belonged to clonal complex (CC) 23 and CC65, respectively, while the other 18 isolates (35.3%) were defined as other STs. CC23 consisted of only K1 strains, while CC65 included only K2 strains. All non-K1/K2 strains were classified as STs other than CC23 and CC65. Approximately 70.6% (36/51) of KLA isolates exhibited an HV phenotype. Both K1 and K2 isolates presented significantly higher prevalence of the pLVPK-derived loci than non-K1/K2 isolates. The K1 isolates had a significantly higher prevalence of the kfu and allS genes than K2 and non-K1/K2 isolates, while the K2 isolates exhibited higher repA prevalence than K1 and non-K1/K2 isolates. The majority of KLA isolates belonged to CC23K1 and CC65K2, while other STs with non-K1/K2 capsular types have also been identified. The virulent factors exhibited diverse distribution among the different clones of KLA isolates.

X-linked agammaglobulinemia combined with juvenile idiopathic arthritis and invasive Klebsiella pneumoniae polyarticular septic arthritis

X-linked agammaglobulinemia (XLA) is a primary immunodeficiency disease caused by mutations in the Bruton's tyrosine kinase (BTK) gene. XLA can also present in combination with juvenile idiopathic arthritis (JIA), the major chronic rheumatologic disease in children. We report herein the first known case of a juvenile patient diagnosed with XLA combined with JIA that later developed into invasive Klebsiella pneumoniae polyarticular septic polyarthritis. An additional comprehensive review of XLA combined with JIA and invasive K. pneumoniae septic arthritis is also presented. XLA was identified by the detection of BTK mutations while the diagnosis of JIA was established by clinical and laboratory assessments. Septic arthritis caused by invasive K. pneumoniae was confirmed by culturing of the synovia and gene detection of the isolates. Invasive K. pneumoniae infections can not only result in liver abscesses but also septic arthritis, although this is rare. XLA combined with JIA may contribute to invasive K. pneumoniae infection.

Pyogenic Liver Abscess, Bacteremia, and Meningitis with Hypermucoviscous Klebsiella pneumoniae: An Unusual Case Report in a Human T-Cell Lymphotropic Virus Positive Patient of Caribbean Origin in the United States

Pyogenic liver abscess (PLA) is a potentially fatal disease. Klebsiella pneumoniae (K. pneumoniae) has replaced Escherichia coli (E. coli) as the predominant causative organism for pyogenic liver abscess. Over the years a unique form of community-acquired invasive K. pneumoniae infection of the liver has been well described in Southeast Asia. This has recently been linked to a virulent hypermucoviscous K. pneumoniae phenotype and to a specific genotype, rmpA positive. To our knowledge, we report the first case of PLA with bacteremia and meningitis in a Guyanese patient with the presence of rmpA-positive K. pneumoniae with laboratory evidence in North America.

Community-acquired Klebsiella pneumoniae liver abscess: an emerging infection in Ireland and Europe

INTRODUCTION

Klebsiella pneumoniae has emerged as a predominant cause of community-acquired mono-microbial pyogenic liver abscess. This was first described in Taiwan and has been widely reported in Asia. This infectious entity has been described in Europe, with single case reports predominating.

METHODS

We present three cases in one year from our institution in Ireland and review the European literature to date.

RESULTS/CONCLUSION

Klebsiella pneumoniae invasive liver abscess syndrome is now emerging in Europe and notably is not restricted to individuals of Asian descent.

Interaction of dihydrofolate reductase and aminoglycoside adenyltransferase enzyme from Klebsiella pneumoniae multidrug resistant strain DF12SA with clindamycin: a molecular modelling and docking study

Klebsiella pneumoniae strain DF12SA (HQ114261) was isolated from diabetic foot wounds. The strain showed resistance against ampicillin, kanamycin, gentamicin, streptomycin, spectinomycin, trimethoprim, tetracycline, meropenem, amikacin, piperacillin/tazobactam, augmentin, co-trimoxazole, carbapenems, penicillins and cefoperazone, and was sensitive to clindamycin. Molecular characterization of the multidrug-resistance phenotype revealed the presence of a class 1 integron containing two genes, a dihydrofolate reductase (DHFR) (PF00186), which confers resistance to trimethoprim; and aminoglycoside adenyltransferase (AadA) (PF01909), which confers resistance to streptomycin and spectinomycin. A class 1 integron in K. pneumoniae containing these two genes was present in eight (18.18%) out of 44 different diabetic foot ulcer (DFU) patients. Hence, there is a need to develop therapeutics that inhibit growth of multidrug resistant K. pneumoniae in DFU patients and still achieve amputation control. Am attempt was made to create a 3D model and find a suitable inhibitor using an in silico study. Rational drug design/testing requires crystal structures for DHFR and AadA. However, the structures of DHFR and AadA from K. pneumoniae are not available. Modelling was performed using Swiss Model Server and Discovery Studio 3.1. The PDBSum server was used to check stereo chemical properties using Ramachandran plot analysis of modeled structures. Clindamycin was found to be suitable inhibitor of DHFR and AadA. A DockingServer based on Autodock & Mopac was used for docking calculations. The amino acid residues Ser(32), Ile(46), Glu(53), Gln(54), Phe(57), Thr(72), Met(76), Val(78), Leu(79), Ser(122), Tyr(128), Ile(151) in case of DHFR and Phe(34), Asp(60), Arg(63), Gln(64), Leu(68), Glu(87), Thr(89), Val(90) for AadA were found to be responsible for positioning clindamycin into the active site. The study identifies amino acid residues crucial to 'DHFR and AadA -drug' and 'DHFR and AadA -inhibitor' interactions that might be useful in the ongoing search for a versatile DHFR and AadA -inhibitor.

Revealing the functionality of hypothetical protein KPN00728 from Klebsiella pneumoniae MGH78578: molecular dynamics simulation approaches

Background

Previously, the hypothetical protein, KPN00728 from Klebsiella pneumoniae MGH78578 was the Succinate dehydrogenase (SDH) chain C subunit via structural prediction and molecular docking simulation studies. However, due to limitation in docking simulation, an in-depth understanding of how SDH interaction occurs across the transmembrane of mitochondria could not be provided.

Results

In this present study, molecular dynamics (MD) simulation of KPN00728 and SDH chain D in a membrane was performed in order to gain a deeper insight into its molecular role as SDH. Structural stability was successfully obtained in the calculation for area per lipid, tail order parameter, thickness of lipid and secondary structural properties. Interestingly, water molecules were found to be highly possible in mediating the interaction between Ubiquinone (UQ) and SDH chain C via interaction with Ser27 and Arg31 residues as compared with earlier docking study. Polar residues such as Asp95 and Glu101 (KPN00728), Asp15 and Glu78 (SDH chain D) might have contributed in the creation of a polar environment which is essential for electron transport chain in Krebs cycle.

Conclusions

As a conclusion, a part from the structural stability comparability, the dynamic of the interacting residues and hydrogen bonding analysis had further proved that the interaction of KPN00728 as SDH is preserved and well agreed with our postulation earlier.

[Severe primary liver abscess and septic pulmonary embolism due to Klebsiella pneumoniae with hypermucoviscosity phenotype]

A 70-year-old man with diabetes mellitus seen for fever, right chest pain, and right-lung field consolidation on chest X-ray was found in thoracoabdominal computed tomography (CT) to have variable-sized nodules in both lung fields and multiple low-density hepatic areas. On physical examination, his pulse was 145 beats per minute and blood pressure 92/68mmHg, indicating a preshock state. Laboratory tests showed elevated WBC of 15,200/microL, serum-C-reactive protein (CRP) of 34.4 mg/dL, and a decreased platelet count of 16,000/microL. Suspecting liver abscesses complicated by a septic pulmonary embolism, we immediately conducted percutaneous transhepatic abscess drainage (PTAD). Liver abscess blood culture and drainage fluid grew the Klebsiella pneumoniae hypermucoviscosity phenotype, carrying the rmpA gene. Although the man had been in critical condition on admission, broad-spectrum antibiotics and PTAD treatment improved his clinical condition to where he could be discharged without problem.

Appearance of Klebsiella pneumoniae liver abscess syndrome in Argentina: case report and review of molecular mechanisms of pathogenesis

Klebsiella pneumoniae liver abscess syndrome (KLAS) is an emerging invasive infection caused by highly virulent community-acquired strains of K. pneumoniae displaying hypermucoviscosity. The salient features of this syndrome include the presence of bacteremia, primary monomicrobial liver abscess, and metastatic complications. A previously healthy Argentinean man presented with fever and found to have liver abscess caused by K. pneumoniae with metastatic seeding of gastric wall. Cultures from blood and liver abscess grew hypermucoviscous K1 K. pneumoniae with sequence type (ST) 23 by multilocus sequence typing (MLST), positive for rmpA (regulator of mucoid phenotype A), wzy_KpK1 (capsular polymerase) and aerobactin genes. The hypermucoviscous phenotype of this K. pneumoniae isolate was readily identified by the "string test" (colonies formed a long string when touched with a loop). The patient responded favourably to percutaneous drainage of the abscess and antibiotics. This is the first documented report of KLAS described in Argentina, and may signal the emergence of this syndrome in South America.

Hypermucoviscosity associated with Klebsiella pneumoniae-mediated invasive syndrome: a prospective cross-sectional study in Taiwan

OBJECTIVES

To investigate the association between Klebsiella pneumoniae-mediated invasive syndrome and underlying diseases in patients and/or K. pneumoniae characteristics, including the rmpA, rmpA2, and magA genes, capsular polysaccharide (cps) K(1) or K(2) serotypes, hypermucoviscosity (HV) phenotype, and extended-spectrum beta-lactamase (ESBL) production.

METHODS

This was a prospective cross-sectional study.

RESULTS

The invasive syndrome was detected in 19 of 91 patients (20.9%) with K. pneumoniae infections, and diabetes mellitus was the most common underlying disease (9 of 19). The presence of rmpA or rmpA2 was found in 91.4% of the 35 isolates with the HV phenotype, while in only 17.9% of the 56 isolates without HV phenotype. Multivariate logistic regression analysis showed that the HV phenotype was an independent risk factor for K. pneumoniae-mediated invasive syndrome (odds ratio (OR) 58.24, 95% confidence interval (CI) 7.23-468.87; p < 0.001) and was negatively associated with ESBL production (OR 0.042, 95% CI 0.005-0.331; p=0.003). Binary logistic regression analysis revealed that the invasive syndrome was not influenced by the presence of diabetes mellitus among patients infected with K. pneumoniae positive for the rmpA or rmpA2 gene, HV phenotype, or cps K(1)/K(2) serotype.

CONCLUSIONS

The HV phenotype of K. pneumoniae contributes to invasive syndrome and is a negative predictor for K. pneumoniae acquisition of ESBLs.

Why hypothetical protein KPN00728 of Klebsiella pneumoniae should be classified as chain C of succinate dehydrogenase?

Twenty percent of genes that encode for hypothetical proteins from Klebsiella pneumoniae MGH78578 were identified, leading to KPN00728 and KPN00729 after bioinformatics analysis. Both open reading frames showed high sequence homology to Succinate dehydrogenase Chain C (SdhC) and D (SdhD) from Escherichia coli. Recently, KPN00729 was assigned as SdhD. KPN00728 thus remains of particular interest as no annotated genes from the complete genome sequence encode for SdhC. We discovered KPN00728 has a missing region with conserved residues important for ubiquinone (UQ) and heme group binding. Structure and function prediction of KPN00728 coupled with secondary structure analysis and transmembrane topology showed KPN00728 adopts SDH-(subunit C)-like structure. To further probe its functionality, UQ was docked on the built model (consisting KPN00728 and KPN00729) and formation of hydrogen bonds between UQ and Ser27, Arg31 (KPN00728) and Tyr84 (KPN00729) further reinforces and supports that KPN00728 is indeed SDH. This is the first report on the structural and function prediction of KPN00728 of K. pneumoniae MGH78578 as SdhC.

Bartholin's abscess caused by hypermucoviscous Klebsiella pneumoniae

Klebsiella pneumoniae serogroups displaying the hypermucoviscosity phenotype are associated with a distinct clinical syndrome characterized by liver abscesses, bacteraemia and metastatic lesions. We describe here what we believe to be the first reported case of hypermucoviscous K. pneumoniae causing a superficial Bartholin's abscess in the absence of systemic involvement.

Invasive infection with hypermucoviscous Klebsiella pneumoniae: multiple cases presenting to a single emergency department in the United States

A distinctive form of community-acquired invasive Klebsiella pneumoniae infection has been well described in Southeast Asia for more than 2 decades. The clinical syndrome includes liver abscess, bacteremia, and metastatic infection. It has recently been linked to a virulent hypermucoviscous K pneumoniae phenotype and to a specific genotype. As of 2008, there were only 2 published cases of invasive infection caused by this strain of K pneumoniae in the United States. We report 4 recent cases presenting to a single public hospital emergency department in northern California, which may signal the emergence of this clinical syndrome in North America.

Multisystemic abscesses in African green monkeys (Chlorocebus aethiops) with invasive Klebsiella pneumoniae--identification of the hypermucoviscosity phenotype

Invasive Klebsiella pneumoniae is an emerging disease of humans characterized by abscesses in the liver or other sites involving bacteria with the unique hypermucoviscosity phenotype. Over several months, 7 African green monkeys in our research colony developed abscess formation in multiple locations and succumbed to disease. K. pneumoniae was identified by bacterial culture in 6 monkeys and immunohistochemistry in 1 additional monkey. All monkeys had been housed in, or had contact with monkeys housed in, 1 animal room in our facility. All affected monkeys had 1 or more abscesses, most notably in the abdomen, but also affecting the lungs, cerebellum, and skin. Abdominal abscesses and associated adhesions entrapped loops of bowel, forming palpable masses. Abdominal masses were located at the root of the mesentery, the ileocecocolic junction, or the pelvic inlet. In 1 case, culture, serotyping, and polymerase chain reaction (PCR) analysis of the bacterial isolate identified K. pneumoniae expressing the hypermucoviscosity phenotype and capsular serotype K2 and determined that the K. pneumonia was genetically rmpA(+)/magA(-).

Invasive Klebsiella pneumoniae syndrome in North America

Invasive liver abscess syndrome, which is caused by hypervirulent Klebsiella pneumoniae subtypes, has been emerging worldwide over the past 2 decades. The syndrome is associated with the hypermucoviscosity phenotype of K. pneumoniae strains and with the magA and rmpA genes. We provide the first laboratory evidence of the presence of rmpA-positive K. pneumoniae in North America.