The emergence of Klebsiella pneumoniae endogenous endophthalmitis in the USA: basic and clinical advances

Klebsiella pneumoniae Endophthalmitis with Subretinal Abscess: A Case Series and Review of the Literature

This study assessed prognostic factors and the role of vitrectomy in patients with subretinal abscesses secondary to K. pneumoniae endophthalmitis. We reviewed published studies, including three cases from our cohort. Among 50 eyes, 26 had poor visual outcomes (final visual acuity <20/800, eyeball removal, or phthisis bulbi). Poor outcomes correlated with delayed ocular symptom-to-diagnosis time, initial visual acuity <20/800, severe vitritis, and macular involvement of abscesses (p < 0.001, p = 0.008, p < 0.001, and p = 0.033, respectively). Vitrectomy had a trend towards reducing eyeball removal and phthisis bulbi rates compared with non-vitrectomy (10.8% vs 30.8%, p = 0.181). However, the final visual acuity was not different and the rate of retinal detachment tended to be higher in vitrectomized eyes (45.9% vs 15.4%, p = 0.095). The study suggested that vitrectomy and drainage of K. pneumoniae subretinal abscesses could be avoided in patients with a mild degree of vitritis.

A Retrospective Review of Endogenous Endophthalmitis: Three Years of Experience at Sultan Ahmad Shah Medical Centre at International Islamic University Malaysia

Introduction Endogenous endophthalmitis is characterized by severe intraocular inflammation caused by the invasion of microorganisms into the anterior and posterior chambers of the eye. It results from hematogenous spread from distant foci of infection. This, in turn, leads to potential vision loss and blindness due to reduced anatomical and functional outcomes. The latest reported prevalence of endogenous endophthalmitis accounts for at least 2-8% of cases of general endophthalmitis which is fairly significant. Purpose This study aimed to analyze the clinical profile of endogenous endophthalmitis presented in the Ophthalmology Clinic, Sultan Ahmad Shah Medical Centre at International Islamic University Malaysia (SASMEC@IIUM). This study includes the patients' demographics, clinical manifestations, causative organism, treatment, and final visual outcome. Methods This is a retrospective case series of endogenous endophthalmitis patients from January 2020 to June 2023. The data were obtained from the patients' medical records in SASMEC@IIUM. Results A total of six patients (six eyes) were diagnosed with endogenous endophthalmitis from January 2020 to June 2023. Four patients (66.6%) were female, with a mean age of 51.6 ± 17.5 years. Presenting visual acuity ranged between 6/21 to hand movement (HM). Five patients (83.3%) presented with reduced vision, while one presented with eye redness (16.6%). Ocular signs included vitritis and retinitis (five eyes, 83.3%), hypopyon (five eyes, 83.3%), injected conjunctiva (five eyes, 83.3%), and eyelid swelling (one eye, 16.6%). The most common primary infection seen was intraabdominal sepsis (three patients, 50%), septic arthritis, hospital-acquired pneumonia (HAP), and urinary tract infection (UTI). Vitreous biopsy was only positive in two patients (33.3%) However, five out of the six patients (83.3%) had positive blood cultures (two Staphylococcus aureus, two Klebsiella pneumoniae and one Pseudomonas aeruginosa). All patients received intravitreal injections and intravenous antibiotics. Only one patient underwent subsequent trans pars plana vitrectomy (TPPV). Final visual acuity ranged from 6/6 to no light perception (NPL). Conclusion In this case series of six patients, we observed a variety of outcomes with similar presentations despite standardized treatment in all patients. Five out of six patients showed poorer visual outcomes and only one patient showed a final visual acuity of 6/6. Therefore, further study with a larger sample size is needed to evaluate the factors associated with the final visual outcome in endogenous endophthalmitis.

Endogenous Endophthalmitis: A 10-Year Review of Cases on the East Coast of Malaysia

Purpose Our study aimed to describe the clinical profile of endogenous endophthalmitis, focusing on patient demographics, infection sources, microbial profiles, clinical outcomes, and factors affecting the final visual outcome. Methods A retrospective review was performed on data from 68 eyes of 60 patients diagnosed with endogenous endophthalmitis and hospitalized in two tertiary hospitals on the East Coast of Peninsular Malaysia from January 2011 to December 2020. The analysis encompassed evaluating patient age, gender, laterality, risk factors, infection origins, presenting and final visual acuity, microbial results, treatment responses, and factors affecting final visual outcomes. Results The average age of the patient cohort was 54.9 ± 13.3 years. Females were more likely to have endogenous endophthalmitis than males (33, 55.0% vs. 27, 45.0%). Twenty-seven patients (45.0%) presented with endogenous endophthalmitis in the left eye, while 25 patients (41.7%) had it in the right eye, and eight patients (13.3%) had bilateral involvement. Most patients had underlying predisposing conditions, predominantly diabetes mellitus (53, 88.3%). Infection sources were identified in 42 patients (70.0%), out of which urinary tract infections account for the majority (11, 18.3%). Klebsiella species(14, 22.7%) were the leading pathogens and were significantly associated with liver abscess cases. In this series, the majority of patients had poor presenting and final visual acuity of worse than 3/60 (56, 82.4% and 53, 77.9%, respectively). Thirty-six eyes (52.9%) underwent vitrectomy, resulting in only four eyes (11.11%) achieving final visual acuity better than 6/12. Presenting visual acuity was identified as the factor contributing to the blind final visual outcome (r = 0.707, p < 0.001). Conclusion Females were found to be more commonly affected by endogenous endophthalmitis than males. Klebsiella species were the most commonly isolated microorganisms and were typically associated with liver abscesses. Urinary tract infection was the most common predisposing factor. A majority of the patients had poor presenting and final visual acuity, in which poor visual acuity is a significant indicator of blind visual outcomes.

Bilateral Endogenous Bacterial Endophthalmitis with Asynchrony for 14 Months due to Klebsiella pneumoniae: A Case Report

Introduction

The aim of this study was to describe a very rare case of endogenous bacterial endophthalmitis caused by Klebsiella pneumoniae in both eyes with a difference in the onset of symptoms of 14 months in an immunocompetent patient.

Case Presentation

A 66-year-old immunocompetent man presented with asynchronous bilateral endogenous endophthalmitis produced by the K. pneumoniae bacterium at the starting point of a liver abscess after cholecystectomy surgery, causing endophthalmitis 1 year and 2 months apart between an eye and another. The first was diffuse anteroposterior endophthalmitis in the left eye that ended in visual loss and phthisis bulbi due to delayed initial diagnosis and established treatment, and the second was focal endophthalmitis in the right eye that preserved the organ and resulted in a vision of 20/20 due to early suspected diagnosis and rapid instituted treatment.

Conclusion

To our knowledge, this is the first published case of a long asynchronous bilateral endogenous bacterial endophthalmitis caused by K. pneumoniae with a prolonged difference of 14 months in the onset of symptoms between one eye and another. This case is a vision-threatening ophthalmologic emergency that can be associated with life-threatening systemic morbidities. The early diagnosis of infection represents a challenge for clinicians, ophthalmologists, and microbiologists.

Klebsiella Endogenous Endophthalmitis During the COVID-19 Pandemic

Purpose: To describe the characteristics of Klebsiella pneumoniae endogenous endophthalmitis (KEE) encountered during the COVID-19 pandemic. Methods: This retrospective consecutive case series evaluated eyes that presented with KEE between March 2020 and July 2022. Results: Seven eyes of 5 patients developed KEE. Between January 2020 and July 2022, KEE was observed in 42% of consecutive EE cases compared with 7.8% during the preceding 13 years. COVID-19 was positive in 4 of 5 patients before they developed KEE. Only 1 patient presented with a VA better than hand motions (20/400). All eyes were treated with urgent vitrectomy and intravitreal and systemic antibiotics. No improvement in vision occurred in any patient; VA remained light perception to no light perception in 60% of eyes. Conclusions: The visual prognosis in KEE is extremely poor. The presence of a preceding COVID-19 infection in 80% of patients may signal a new risk factor for KEE. Patients with a hypervirulent Klebsiella syndrome should be routinely screened for EE.

The making of hypervirulent Klebsiella pneumoniae

Klebsiella pneumoniae is a notorious bacterium in clinical practice. Virulence, carbapenem-resistance and their convergence among K. pneumoniae are extensively discussed in this article. Hypervirulent K. pneumoniae (HvKP) has spread from the Asian Pacific Rim to the world, inducing various invasive infections, such as pyogenic liver abscess, endophthalmitis, and meningitis. Furthermore, HvKP has acquired more and more drug resistance. Among multidrug-resistant HvKP, hypervirulent carbapenem-resistant K. pneumoniae (Hv-CRKP), and carbapenem-resistant hypervirulent K. pneumoniae (CR-HvKP) are both devastating for their extreme drug resistance and virulence. The hypervirulence of HvKP is primarily attributed to hypercapsule, macromolecular exopolysaccharides, or excessive siderophores, although it has many other factors, for example, lipopolysaccharides, fimbriae, and porins. In contrast with classical determination of HvKP, that is, animal lethality test, molecular determination could be an optional and practical method after improvement. HvKP, including Hv-CRKP and CR-HvKP, has been progressing. R-M and CRISPR-Cas systems may play pivotal roles in such evolutions. Hv-CRKP and CR-HvKP, in particular the former, should be of severe concern due to their being more and more prevalent.

Siderophore iucA of hypermucoviscous Klebsiella pneumoniae promotes liver damage in mice by inducing oxidative stress

The hypermucoviscosity/hypervirulent K. pneumoniae (hvKP) is a dominant cause of pyogenic liver abscess (PLA) and has contributed to the endemicity of disease in Asian country. The siderophore aerobactin (iucA) is highly expressed in hvKP and acting virulence role during hvKP infection. However, its role in the PLA is poorly understood. We constructed iucA deletion mutant (ΔiucA-hvKP852) and used animal study to characterize the role of siderophore iucA in K. pneumoniae liver abscess. The animal experiments showed that ΔiucA-hvKP852 strain had lower virulence in mice compared to hvKP852 wild type strain. At 24 h after infection, only two of ten mice developed liver abscess during infection with ΔiucA-hvKP852 strain, while nine of ten mice infected with wild type hvKP852 strain showed multiple lesions of liver abscess. The liver tissue infected with ΔiucA-hvKP852 exhibited low reactive oxygen stress levels compared to those infected by wild type hvKP852 strain (P < 0.05). The results suggest that siderophore iucA play an important role in the liver abscess by inducing oxidative stress.

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iucA positive strains produces more siderophore than iucA negative hvK. pneumoniae.

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Siderophore production is positively related with Oxidative stress in hvK. pneumoniae.

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iucA enhances oxidative stress in liver and forms liver abscess during hvK. pneumoniae infection.

Clinical and genomic characterization of hypervirulent Klebsiella pneumoniae (hvKp) infections via passive surveillance in Southern California, 2020–2022

Hypervirulent Klebsiella pneumoniae (hvKp) is more invasive and virulent than classical K. pneumoniae, and requires specialized treatment. To raise clinical awareness, this study determined the prevalence, clinical characteristics, and genomic epidemiology of hvKp infections in Southern California (SoCal) by conducting a passive surveillance in a single large academic medical center. We report here that hvKp infections were more common than expected, accounting for 2.6% of invasive K. pneumoniae infections, and presented with a wide disease spectrum, occasionally mimicking tumors, even co-infecting a COVID-19 patient. Most infections were community acquired with no recent international travel, suggesting hvKp strains are circulating in the community. Genomic analysis revealed genetic diversity, with the K1-ST23 lineage predominating but not clonal, and multiple sequence types of K2 including a SoCal unique K2-ST66 sublineage that had been unrecognized. Our findings highlight the urgency of heightened awareness of hvKp infection in the US, the need for rapid diagnosis of hvKp, and the necessity of implementing robust surveillance programs for hvKp at the institutional or local level.

Characteristics of Computed Tomography for Identifying Patients at High Risk of Endogenous Endophthalmitis Due to Klebsiella pneumoniae-Related Pyogenic Liver Abscess

Endogenous endophthalmitis (EE) associated with Klebsiella pneumoniae (K. pneumoniae)-related pyogenic liver abscess (PLA) is one of the fatal complications of PLA and leads to loss of vision. Early diagnosis and treatment are important to save the patient’s vision. We investigated the characteristics of computed tomography (CT) in EE associated with K. pneumoniae-related PLA for the identification of the predictors of EE, in order to facilitate early diagnosis. A total of 274 patients diagnosed with K. pneumoniae-related PLA, including 15 patients with EE, were identified between January 2005 and December 2019. The clinical (age, gender, and underlying disease) and radiologic (the location, size, and number of abscesses) features were reviewed. In addition, the involvement of the adjacent vessels, such as the hepatic vein and portal vein, was carefully reviewed. A comparative analysis was performed between the EE and non-EE groups. Uni- and multivariate logistic regression analyses were used to identify the predictors of EE. Diabetes mellitus (DM), the involvement of the left or both hepatic lobes, and the adjacent vessels on the CT were significantly more frequent than those in the non-EE group (p < 0.05 in all), and they were the significant predictors of EE in the logistic regression analyses. In patients with K. pneumoniae-related PLA, the CT findings, such as the locations of the abscess (i.e., left or both lobes) and the involvement of the adjacent vessels, should be considered in addition to the ocular symptoms for an early diagnosis of EE.

Hypervirulent Klebsiella Pneumoniae, an Emerging Cause of Endogenous Endophthalmitis in A French Center: A Comparative Cohort Study

INTRODUCTION

Klebsiella pneumoniae (KP) is the most common cause of endogenous endophthalmitis (EE) in Asia, but data in Europe are scarce. We describe eight cases of KP EE compared to a cohort of EE in a French center.

METHODS

EE cases were retrospectively studied between January 2014 and January 2021. KP EE cases were analyzed to assess clinical, microbiological features, and outcome.

RESULTS

Among the 33 EE cases identified, the first causative agent (24%, n = 8) was KP, mainly (7/8) with hypervirulent phenotype (hvKP). All but one of these cases occurred from December 2019 to January 2021. Contrary to non-KP patients, KP patients had multiple extraocular infective foci (p = .006), all presented with liver abscesses (p < .001), 50% had cerebral involvement (p = .13). Visual outcome was poor in both groups.

CONCLUSION

KP is an emerging cause of EE in a French center, consistently associated with liver abscesses, frequent cerebral involvement, and predominance of hvKP strains.

Endogenous Endophthalmitis-The Clinical Significance of the Primary Source of Infection

Endophthalmitis is a severe form of ocular inflammation. The source of pathogens in endogenous endophthalmitis is located inside the body, and infection spreads hematogenously. Although rare, endogenous endophthalmitis is a very serious condition, as this type of inflammation is very devastating for ocular tissues. Prognosis is very poor, and the patients are often in a serious general condition, so they require special care and an individual approach in the treatment process. Thanks to the knowledge of the risks associated with infections of individual tissues and organs as well as potential pathogens and the clinical picture, it is possible to make a correct diagnosis faster and implement the correct treatment. In the case of endogenous endophthalmitis, reaction time is absolutely crucial for prognosis. In this review, we focus primarily on the importance of the primary source of infection for the course of the disease and prognosis.

Endogenous Endophthalmitis Caused by ST66-K2 Hypervirulent Klebsiella pneumoniae, United States

We describe a case of endogenous endophthalmitis caused by sequence type 66-K2 hypervirulent Klebsiella pneumoniae in a diabetic patient with no travel history outside the United States. Genomic analysis showed the pathogen has remained highly conserved, retaining >98% genetic similarity to the original strain described in Indonesia in 1935.

Hypervirulent Klebsiella pneumoniae Endogenous Endophthalmitis-A Global Emerging Disease

The review aims to document the new emerging hypervirulent Klebsiella pneumoniae (Kp) endogenous endophthalmitis (EKE) in terms of incidence, microbiological characterization of the pathogenic agent, associated risk factors, management, and outcomes. Hypervirulent (hv) strains of KP (hvKp) induce invasive liver abscesses (LA) with specific clinical features. Up to 80–90% of cases have hepatic liver abscess as a primary focus of infection, followed by renal or lung hvKp infections. However, the incidence of EKE in patients with KPLA varied between 3.4% (19) and 12.6% (13), with a total of 95 cases of endophthalmitis in 1455 cases of KPLA (6.5%). Severe visual loss was encountered in 75% of cases, with 25% bilateral involvement. Intravitreal antibiotics are the mainstay therapeutic approach. Pars plana vitrectomy is a subject of controversy. HvKp strains present mostly natural “wild-type” antibiotic resistance profile suggestive for community-acquired infections, being highly susceptive to the third and fourth generation of cephalosporins and carbapenems. Antimicrobial resistance in hypervirulent strains was recently documented via plasmid transfer and may result in extremely difficult to treat cases. Global dissemination of these strains is a major epidemiologic shift that should be considered in the diagnostic and therapeutic management of patients with endogenous endophthalmitis. Ophthalmologic screening in patients with KPLA and other hvKp infections and a multidisciplinary therapeutic approach is extremely important for early diagnosis and preservation of the visual function.

Endogenous Endophthalmitis: A 21-Year Review of Cases at a Tertiary Eye Care Centre

Purpose: Endogenous endophthalmitis is rare and associated with significant morbidity and mortality. The primary objective was to identify causative organisms. Secondary objectives included the determination of systemic risk factors and visual prognostic factors.Design: Retrospective reviewMethods: 78 eyes from 62 subjects over a 21-year period from 1999 to 2020 in Auckland, New Zealand. Parameters assessed included pathologic microbial organism, clinical presentation, treatment, complications, prognostic factors, and visual outcomes.Methods: Information was collected on microbiology, treatment, visual outcomes, and complications.Results: Median age was 61.6 years and 32 subjects (51.6%) were male. Diabetes was the most common risk factor seen in 24 (38.7%) subjects. 17 subjects (27.4%) presented directly to ophthalmology and 17.4% had an initial misdiagnosis. 49 subjects (79.0%) presented with reduced vision and only 27 (43.5%) presented with pain. Hypopyon was present in 13 eyes (16.7%). Gram-positive bacteria were the most common causative organism seen in 40 (51.3%) eyes, followed by yeast and fungi in 21 (26.9%) eyes, then gram-negative bacteria seen in 17 (21.8%) eyes. Median final BCVA was 6/18. Severe vision loss occurred in 33 (42.3%) eyes and 7 (9.0%) eyes required evisceration or enucleation. Presenting visual acuity was a significant predictor of visual outcome.Conclusion: Endogenous endophthalmitis occurred at 1.9 cases per million per year. Ophthalmologists require a high index of suspicion for underlying systemic infection in any subject presenting with ocular inflammation, and need to be aware that endogenous endophthalmitis may present without pain and frequently without hypopyon.

Surgery combined with antibiotics for the treatment of endogenous endophthalmitis caused by liver abscess

Backgrounds

Endogenous endophthalmitis is a serious disease caused by intraocular infection that can rapidly progress to cause blindness. This study evaluated the clinical features, surgical and antibiotics treatment strategies, and treatment outcomes in patients with endophthalmitis caused by liver abscess.

Methods

Between April 2014 and April 2019, the clinical data of 16 patients (19 eyes) with endophthalmitis associated with liver abscess who underwent surgery at Shengjing Hospital were retrospectively analyzed. Furthermore, we evaluated the final visual outcomes in the patients to determine the efficacy of surgery.

Results

Fifteen patients (18 eyes) underwent intravitreal injection followed by vitrectomy after admission. One patient (1 eye) only underwent intravitreal injection. Of the 16 patients, 3 patients (3 eyes) had recurrent intraocular inflammation and eventually underwent evisceration. Systemic antibiotics were administered for all patients based on the results of vitreous humor culture, blood culture, and antibiotic susceptibility tests. Outpatient follow-ups were performed until the patients were stable (6 months). Of the 19 eyes, 1 eye (5%) had visual acuity restored to 20/200, 6 eyes (31%) had visual acuity restored to counting fingers (CF), 2 eyes (11%) had visual acuity restored to hand motion (HM), 4 eyes (22%) showed only light perception (LP), and the remaining 6 eyes (31%) showed no light perception (NLP). Drug susceptibility tests suggested that the carbapenems exhibited significant effects in the inflammatory reaction.

Conclusion

Endogenous endophthalmitis caused by liver abscess is a very serious condition, and the final visual outcome is poor. Timely surgical intervention combined with antibiotic treatment is essential, and the primary disease must be treated to control disease progression at the earliest.

Report of Four Cases of Endogenous Klebsiella Pneumoniae Endophthalmitis Originated from Liver Abscess with Eye Complaints as the Initial Presentations

PURPOSE

To report four cases of endogenous endophthalmitis (EE) secondary to Klebsiella pneumoniae liver abscess, and discuss their clinic features and outcomes.

METHODS

Clinical data were collected by reviewing the medical records of four patients diagnosed with endogenous Klebsiella Pneumoniae endophthalmitis (EKPE) secondary to liver abscess.

RESULTS

Four patients were diagnosed with EE. Two males and two females, with ages ranging from 33 to 63 years old. All patients presented with ocular symptoms initially. Liver abscesses were diagnosed during hospitalization. All cases were caused by Klebsiella Pneumoniae confirmed by blood or tissue cultures. All patients were treated with intravitreal antibiotic injection, and two of the patients had vitrectomy. At the end, all affected eyes underwent evisceration. One patient died of septic shock with multiple organ failures.

CONCLUSION

EE secondary to liver abscess with metastatic spread is a severe sight-threatening condition. The delayed discovery of liver abscess may hinder the diagnosis and treatment of the disease, which may be related to poor prognosis.

The cereus matter of Bacillus endophthalmitis

Bacillus cereus (B. cereus) endophthalmitis is a devastating intraocular infection primarily associated with post-traumatic injuries. The majority of these infections result in substantial vision loss, if not loss of the eye itself, within 12-48 h. Multifactorial mechanisms that lead to the innate intraocular inflammatory response during this disease include the combination of robust bacterial replication, migration of the organism throughout the eye, and toxin production by the organism. Therefore, the window of therapeutic intervention in B. cereus endophthalmitis is quite narrow compared to that of other pathogens which cause this disease. Understanding the interaction of bacterial and host factors is critical in understanding the disease and formulating more rational therapeutics for salvaging vision. In this review, we will discuss clinical and research findings related to B. cereus endophthalmitis in terms of the organism's virulence and inflammogenic potential, and strategies for improving of current therapeutic regimens for this blinding disease.

Hypervirulent Klebsiella pneumoniae - clinical and molecular perspectives

Hypervirulent Klebsiella pneumoniae (hvKp) has emerged as a concerning global pathogen. hvKp is more virulent than classical K. pneumoniae (cKp) and capable of causing community-acquired infections, often in healthy individuals. hvKp is carried in the gastrointestinal tract, which contributes to its spread in the community and healthcare settings. First recognized in Asia, hvKp arose as a leading cause of pyogenic liver abscesses. In the decades since, hvKp has spread globally and causes a variety of infections. In addition to liver abscesses, hvKp is distinct from cKp in its ability to metastasize to distant sites, including most commonly the eye, lung and central nervous system (CNS). hvKp has also been implicated in primary extrahepatic infections including bacteremia, pneumonia and soft tissue infections. The genetic determinants of hypervirulence are often found on large virulence plasmids as well as chromosomal mobile genetic elements which can be used as biomarkers to distinguish hvKp from cKp clinical isolates. These distinct virulence determinants of hvKp include up to four siderophore systems for iron acquisition, increased capsule production, K1 and K2 capsule types, and the colibactin toxin. Additionally, hvKp strains demonstrate hypermucoviscosity, a phenotypic description of hvKp in laboratory conditions that has become a distinguishing feature of many hypervirulent isolates. Alarmingly, multidrug-resistant hypervirulent strains have emerged, creating a new challenge in combating this already dangerous pathogen.

Endophthalmitis in HIV Infection

Purpose: The role of HIV infection in exogenous and endogenous endophthalmitis has not been clarified. We aim to assess the potential role of HIV as a risk factor or a poor prognostic feature in this sight-threatening condition. Methods: Literature review. Review of evidence: Evidence for endophthalmitis in HIV patients is based on scarce retrospective case series and case reports. Infrequency of literature on this topic is owed to the diversity of the different types of endophthalmitis as well as the rarity of the coexistence of the two conditions. Conclusions: Endophthalmitis in HIV patients are a rare but potentially devastating condition. Many forms of endophthalmitis tend to occur in severely immunosuppressed HIV patients with low CD4 counts. Therefore, the early introduction of cART with full immune reconstitution is an essential part of the prevention of endophthalmitis in the HIV population.

Klebsiella pneumoniae endogenous endophthalmitis presenting as orbital cellulitis

This report describes the first documented case of Klebsiella pneumoniae endogenous endophthalmitis with concurrent orbital cellulitis in a patient without a liver abscess. A 34-year-old, caucasian male with a history of intravenous drug abuse and type 1 diabetes mellitus was transferred from an outside hospital for progressively worsening pain and swelling in the right eye. Careful history, physical examination, and imaging were consistent with a diagnosis of endogenous endophthalmitis with concurrent orbital cellulitis. Vitreous cultures were positive for Klebsiella pneumoniae. Despite aggressive and early intervention with antibiotics and vitrectomy, the patient's condition continued to worsen and evisceration was required to adequately control the infection. Klebsiella pneumoniae endogenous endophthalmitis with concurrent orbital cellulitis is a rare and often blinding infection, despite appropriately aggressive intervention.

Getting hypervirulent Klebsiella pneumoniae on the radar screen

PURPOSE OF REVIEW

Two pathotypes of Klebsiella pneumoniae cause human infections, classical (cKp) and hypervirulent (hvKp) K. pneumoniae. The present understanding of genetic elements, the need for an accurate test to identify hvKp, the clinical implications of infection, the knowledge gap on how and why hvKp colonization transitions to infection, and potential infection prevention and control issues for hvKp are discussed.

RECENT FINDINGS

Infections because of hvKp are increasingly recognized worldwide. Its ability to cause organ and life-threatening disease in healthy individuals from the community merits concern, which has been magnified by increasing descriptions of multiply drug-resistant (MDR) and extensively drug-resistant (XDR) strains. Increased capsule and siderophore production by hvKp relative to cKp are critical virulence traits. Asians are most commonly infected, but whether this is mediated by a genetic susceptibility, or increased exposure and colonization is unknown. Specific studies about the epidemiology and transmission of hvKp are lacking, but precautions are appropriate for MDR/XDR strains and perhaps all infected/colonized individuals.

SUMMARY

hvKp is evolving into an increasingly concerning pathogen, in part because of the development of XDR strains. An accurate test to identify hvKp is needed for optimal clinical care, epidemiological, and research studies. An improved understanding of how infection develops, if a genetic susceptibility exists, and appropriate infection prevention and control measures also are needed.

Mass spectrometry and associated technologies delineate the advantageously biomedical capacity of siderophores in different pathogenic contexts

Siderophores are chemically diverse small molecules produced by microorganisms for chelation of irons to maintain their survival and govern some important biological functions, especially those cause that infections in hosts. Still, siderophores can offer new insight into a better understanding of the diagnosis and treatments of infectious diseases from the siderophore biosynthesis and regulation perspective. Thus, this review aims to summarize the biomedical value and applicability of siderophores in pathogenic contexts by briefly reviewing mass spectrometry (MS)-based chemical biology and translational applications that involve diagnosis, pathogenesis, and therapeutic discovery for a variety of infectious conditions caused by different pathogens. We highlight the advantages and disadvantages of siderophore discovery and applications in pathogenic contexts. Finally, we propose a panel of new and promising strategy as precision-modification metabolomics method, to rapidly advance the discovery of and translational innovations pertaining to these value compounds in broad biomedical niches. © 2018 Wiley Periodicals, Inc. Mass Spec Rev XX:XX-XX, 2018.

Prognostic Factors and Visual Outcomes of Pyogenic Liver Abscess-Related Endogenous Klebsiella pneumoniae Endophthalmitis: A 20-year retrospective review

Endogenous K. pneumoniae endophthalmitis (EKE) has a higher incidence among East Asians, and the most common infectious source of EKE is pyogenic liver abscess (PLA). We investigate the risk factors for poor visual outcomes in patients with PLA-related EKE. The retrospective medical records of 104 patients (120 eyes) diagnosed with PLA-related EKE between 1996 and 2015. In univariate logistic regression analysis, the risk factors for poor visual outcomes were initial visual acuity (VA) worse than counting fingers (CF) (p < 0.001), eye pain (p = 0.013), hypopyon (p = 0.003), ocular hypertension (p = 0.003), positive intraocular fluids cultures (p < 0.001), subretinal abscess (p = 0.025), unilateral involvement (p = 0.017), delayed ophthalmologic visit (p = 0.022), initially presented with ocular symptoms ahead of systemic symptoms (p < 0.001), and corneal edema (p < 0.001). Intravitreal dexamethasone reduced the requirement of enucleation or evisceration (p = 0.01). The multivariate logistic regression revealed that poor initial VA worse than CF (p = 0.004) and initially presented with ocular symptoms ahead of systemic symptoms (p = 0.007) were the significant independent factors for poor visual outcomes. Early diagnosis and prompt treatment may salvage useful vision in some eyes.

Endogenous endophthalmitis caused by a multidrug-resistant hypervirulent Klebsiella pneumoniae strain belonging to a novel single locus variant of ST23: first case report in China

Background

Endogenous endophthalmitis caused by hypervirulent Klebsiella pneumoniae (HVKP) is an emerging infectious disease commonly with a devastating visual outcome. Most HVKP strains display a wild-type susceptibility profile to antibiotics. However, reports of antimicrobial-resistant HVKP have increased over time, which poses a serious therapeutic dilemma.

Case presentation

A 25-year-old man with a liver abscess and poorly controlled diabetes mellitus was admitted for endophthalmitis due to K. pneumoniae. The isolate displayed hypermucoviscosity as determined by a positive string test and exhibited resistance to ceftazidime, piperacillin-tazobactam and amikacin. Whole genome sequencing (WGS) analysis demonstrated the isolate to be a K1-serotype strain and belong to a novel single locus variant of ST23, ST2922. In addition to the virulence genes linked to HVKP, rmpA, magA, iucABCDiutA (aerobactin), ybtAPSTUX (yersiniabactin) and iroBDN (salmochelin), it was found to harbor extended-spectrum β-lactamase (ESBL) gene (bla_CTX-M-14), AmpC β-lactamase gene (bla_DHA), and 16S rRNA methylase gene (armA).

Conclusions

This is the first known case of endogenous endophthalmitis caused by a multidrug-resistant HVKP strain ever reported in China. Early diagnosis and treatment with intravenous and intravitreal injection of carbapenem were essential for a favorable visual outcome.

Endogenous Endophthalmitis: A Five-year Review of Cases at the Raja Perempuan Zainab II Hospital, Kelantan, Malaysia

Background Endogenous endophthalmitis (EE) is a type of intraocular inflammation secondary to hematogenous spread from a distant infective source within the body and usually occurs in immunocompromised patients. Objectives The aim of this study was to profile the patient characteristics, sources of infection, microbial profiles, and visual outcomes of patients with EE in Raja Perempuan Zainab II Hospital in Kelantan, Malaysia. Materials and methods Data from 18 eyes of 17 patients diagnosed with EE and admitted to the eye ward of Raja Perempuan Zainab II Hospital from January 2012 to December 2016 were retrospectively reviewed. Factors analyzed included patient age, sources of infection, visual acuity, microbial profiles, and treatment outcomes. Results The mean age of the 17 patients was 53.2 years. Twelve patients (70.6%) had EE of left eye, four (23.5%) had EE of right eye, and one (5.9%) had EE involving both the eyes. Sixteen patients (91.1%) had at least one predisposing condition, the most common of which was diabetes mellitus in 15 patients (88.2%). A source of infection was identified in 12 of the 17 patients, with urinary tract infection being the most common (five patients, 29.4%). Organisms were successfully isolated from 10 (58.8%) patients, including seven (41.2%) with Gram-negative and three (17.6%) with Gram-positive organisms. All patients presented with a visual acuity worse than 6/60. Nine (52.9%) patients underwent vitrectomy, with only two of these patients achieving a final visual acuity better than 6/60. Eleven patients became nonperceptive to light, with four of them undergoing evisceration. Conclusions EE is a rare but often devastating ocular condition. Visual outcomes are often poor especially in patients infected with Gram-negative bacteria.

Structural and functional delineation of aerobactin biosynthesis in hypervirulent Klebsiella pneumoniae

Aerobactin, a citryl-hydroxamate siderophore, is produced by a number of pathogenic Gram-negative bacteria to aid in iron assimilation. Interest in this well-known siderophore was reignited by recent investigations suggesting that it plays a key role in mediating the enhanced virulence of a hypervirulent pathotype of Klebsiella pneumoniae (hvKP). In contrast to classical opportunistic strains of K. pneumoniae, hvKP causes serious life-threatening infections in previously healthy individuals in the community. Multiple contemporary reports have confirmed fears that the convergence of multidrug-resistant and hvKP pathotypes has led to the evolution of a highly transmissible, drug-resistant, and virulent "super bug." Despite hvKP harboring four distinct siderophore operons, knocking out production of only aerobactin led to a significant attenuation of virulence. Herein, we continue our structural and functional studies on the biosynthesis of this crucial virulence factor. In vivo heterologous production and in vitro reconstitution of aerobactin biosynthesis from hvKP was carried out, demonstrating the specificity, stereoselectivity, and kinetic throughput of the complete pathway. Additionally, we present a steady-state kinetic analysis and the X-ray crystal structure of the second aerobactin synthetase IucC, as well as describe a surface entropy reduction strategy that was employed for structure determination. Finally, we show solution X-ray scattering data that support a unique dimeric quaternary structure for IucC. These new insights into aerobactin assembly will help inform potential antivirulence strategies and advance our understanding of siderophore biosynthesis.

Isolates and antibiotic susceptibilities of endogenous bacterial endophthalmitis: A retrospective multicenter study in Japan

Endogenous bacterial endophthalmitis, also called metastatic endophthalmitis, is a rare bacterial endophthalmitis derived from distant infectious foci via the bloodstream. This infection can potentially cause not only severe visual disturbance, but also loss of the eyeball or death, as most patients are immunocompromised. This retrospective Japanese multicenter study analyzed 32 eyes in 25 definitive cases. Twelve patients (48.0%) had diabetes mellitus. Typical ocular findings were vitreous haze (87.5%), cells in the anterior chambers (62.5%) and retinal infiltrates (50.0%). Elevated body temperature (64.0%), high serum C-reactive protein (96.0%) and leukocytosis (52.0%) were also frequently observed. Culture positivity rates for intraocular fluid were higher in the vitreous (62.5%) versus aqueous humor (28.6%). High positivity rates were also observed for blood (57.1%) and central venous catheters (100%). The most common pathogen was Staphylococcus aureus (10 cases), including methicillin-resistant S. aureus (4 cases). The next most common pathogen was Klebsiella pneumoniae (7 cases), which was highly associated with liver abscess. Compared to a previous 1991 national multicenter study, there has been a fourfold increase in the ratio of S. aureus. Antibiotic susceptibility tests revealed that all Gram-positives were susceptible to vancomycin and all Gram-negatives were susceptible to third-generation cephalosporins, imipenem/cilastatin, gentamycin and levofloxacin. Prognostic factors influencing poor visual outcome included poor initial visual acuity (p < 0.01), K. pneumoniae (p = 0.027) and gram-negative bacteria (p = 0.014) as the causative bacteria. Intravitreal antibiotic injection in combination with vancomycin and ceftazidime may be applicable for use as part of the standard treatment regimen for EBE.

Infectious Sources, Prognostic Factors, and Visual Outcomes of Endogenous Klebsiella pneumoniae Endophthalmitis

PURPOSE

To investigate the infectious sources and prognostic factors for poor visual outcome, including subjective symptoms, presenting clinical features, laboratory data, and treatments, in patients diagnosed with endogenous Klebsiella pneumoniae endophthalmitis (EKE) at a tertiary referral center in Northern Taiwan.

DESIGN

Retrospective, single-institution, consecutive case series.

PARTICIPANTS

One hundred ten consecutive patients (124 eyes) diagnosed with EKE.

METHODS

One hundred ten patients (124 eyes) were reviewed retrospectively between January 1996 and April 2013.

MAIN OUTCOME MEASURES

Visual acuity (VA), subjective symptoms, presenting clinical features, laboratory data, treatments, and requirement of evisceration or enucleation.

RESULTS

Of the 110 patients with EKE, 74 (67.3%) were men. Diabetes was the most commonly associated systemic disease (75/110 [68.2%]), and liver abscess was the major infection source (85/110 [77.3%]). In addition, 91 of 124 eyes (73.4%) had final VA worse than counting fingers (CF; poor visual outcome), and 20 eyes required evisceration or enucleation. The binary multivariate logistic regression (forward-Wald) model revealed that poor initial VA worse than CF (odds ratio [OR], 8.8; 95% confidence interval [CI], 2.2-36; P = 0.002), positive vitreous culture results (OR, 9.8; 95% CI, 1.7-56.1; P = 0.010), posterior focal EKE (OR, 0.15; 95% CI, 0.03-0.8; P = 0.027), and the presence of intravitreal dexamethasone administration (OR, 0.19; 95% CI, 0.04-0.9; P = 0.030) were the significant independent factors for visual outcomes.

CONCLUSIONS

Liver abscess was the major infection source, and EKE typically has poor visual prognosis. Early diagnosis and prompt treatment may salvage useful vision in some eyes. Early diagnosis with fair initial VA and intravitreal antibiotic and dexamethasone combination therapy may have beneficial effects on visual outcomes.

Metabolite Transporter PEG344 Is Required for Full Virulence of Hypervirulent Klebsiella pneumoniae Strain hvKP1 after Pulmonary but Not Subcutaneous Challenge

Hypervirulent Klebsiella pneumoniae (hvKP) is an emerging pathotype that is capable of causing tissue-invasive and organ- and life-threatening infections in healthy individuals from the community. Knowledge on the virulence factors specific to hvKP is limited. In this report, we describe a new factor (PEG344) that increases the virulence of hvKP strain hvKP1. peg-344 is present on the hvKP1 virulence plasmid, is broadly prevalent among hvKP strains, and has increased RNA abundance when grown in human ascites. An isogenic derivative of hvKP1 (hvKP1Δpeg-344) was constructed and compared with its wild-type parent strain in in vitro, ex vivo, and infection model studies. Both survival and competition experiments with outbred CD1 mice demonstrated that PEG344 was required for full virulence after pulmonary challenge but, interestingly, not after subcutaneous challenge. In silico analysis suggested that PEG344 serves as an inner membrane transporter. Compared to hvKP1, a small but significant decrease in the growth/survival of hvKP1Δpeg-344 was observed in human ascites, but resistance to the bactericidal activity of complement was similar. These data suggested that PEG344 may transport an unidentified growth factor present in ascites. The data presented are important since they expand our limited knowledge base on virulence factors unique to hvKP, which is needed to lay the groundwork for translational approaches to prevent or treat these devastating infections.

A Serendipitous Mutation Reveals the Severe Virulence Defect of a Klebsiella pneumoniae fepB Mutant

Klebsiella pneumoniae is considered a significant public health threat because of the emergence of multidrug-resistant strains and the challenge associated with treating life-threatening infections. Capsule, siderophores, and adhesins have been implicated as virulence determinants of K. pneumoniae, yet we lack a clear understanding of how this pathogen causes disease. In a previous screen for virulence genes, we identified a potential new virulence locus and constructed a mutant (smr) with this locus deleted. In this study, we characterize the smr mutant and show that this mutation renders K. pneumoniae avirulent in a pneumonia model of infection. The smr mutant was expected to have a deletion of three genes, but subsequent genome sequencing indicated that a much larger deletion had occurred. Further analysis of the deleted region indicated that the virulence defect of the smr mutant could be attributed to the loss of FepB, a periplasmic protein required for import of the siderophore enterobactin. Interestingly, a ΔfepB mutant was more attenuated than a mutant unable to synthesize enterobactin, suggesting that additional processes are affected. As FepB is highly conserved among the members of the family Enterobacteriaceae, therapeutic targeting of FepB may be useful for the treatment of Klebsiella and other bacterial infections. IMPORTANCE In addition to having a reputation as the causative agent of several types of hospital-acquired infections, Klebsiella pneumoniae has gained widespread attention as a pathogen with a propensity for acquiring antibiotic resistance. It is capable of causing a range of infections, including urinary tract infections, pneumonia, and sepsis. Because of the rapid emergence of carbapenem resistance among Klebsiella strains, there is a dire need for a better understanding of virulence mechanisms and identification of new drug targets. Here, we identify the periplasmic transporter FepB as one such potential target.

Endophthalmitis

Endophthalmitis is a rare but severe form of ocular inflammation due to infection of the intraocular cavity that can lead to irreversible visual loss if not treated properly and timely. It can be classified as exogenous or endogenous based on the transmission route of the infectious source. Exogenous endophthalmitis occurs when infecting organisms gain entry into the eye via direct inoculation, while endogenous endophthalmitis occurs when infectious agents hematogenously spread into the eye from a distant focus of infection. The diagnosis of endophthalmitis depends mostly on the clinical findings on ophthalmological examination. Delayed diagnosis of endogenous endophthalmitis can lead to not only visual loss, but also increased risk of mortality. Since ocular and systemic symptoms of endophthalmitis are usually non-specific, early diagnosis relies on the alertness of clinicians. Early diagnosis and proper treatment are keys to saving the eye. Following advances in vitreoretinal pharmacotherapy and surgical technology, early surgical intervention is the current trend in the management of endophthalmitis.

Antibody-free detection of infectious bacteria using quantum dots-based barcode assay

Staphylococcus aureus, methicillin-resistant Staphylococcus aureus and Klebsiella pneumoniae are the most representative bacteria causing infectious diseases. Due to the increased application of antibiotics, the bacterial resistance is growing causing severe complications. Therefore, a sensitive determination of these pathogens is crucial for effective treatment. The aim of this study was to design an effective method for multiplex detection of Staphylococcus aureus, methicillin-resistant Staphylococcus aureus and Klebsiella pneumoniae taking advantage from properties of magnetic particles as well as fluorescent nanoparticles (quantum dots). The method was able to detect as low concentrations of bacteria as 10² CFU/mL using the bacteria-specific genes (fnbA, mecA and wcaG).

Rising trends of endogenous Klebsiella pneumoniae endophthalmitis in Australia

BACKGROUND

Endogenous Klebsiella pneumoniae endophthalmitis (EKPE) is a well-known entity in South-East Asia. We demonstrate a range of differing clinical features and outcomes of EKPE, and highlight the increasing incidence of EKPE in major centres in Sydney and Melbourne, Australia.

DESIGN

Retrospective observational case study and case series in the hospital setting.

PARTICIPANTS

Four cases of EKPE.

METHODS

EKPE cases from 2005 to 2015 were identified through established endophthalmitis databases as well as hospital-based microbiological searches.

MAIN OUTCOME MEASURES

EKPE cases were confirmed with positive K. pneumoniae intraocular samples.

RESULTS

Rising trends of EKPE were noted in major centres in Australia. Six eyes of four patients with EKPE from January 2011 to December 2015 are reported. The mean age was 49 years (range 43-58 years). Two patients had bilateral involvement. There were systemic symptoms up to 10 days prior to ocular symptoms. The source of sepsis in all cases was a hepatic abscess. Two patients had diabetes mellitus. Five eyes had hypopyon panuveitis on presentation. All eyes underwent vitrectomy. The patient with the most delayed presentation underwent enucleation following globe perforation. Final best corrected visual acuity (BCVA) in one patient with bilateral EKPE was light perception (LP) only. The other three eyes had BCVA in at least one eye of 6/24 or better.

CONCLUSIONS

EKPE is an emerging condition in Australia. Although rare, EKPE is a sight-threatening and potentially life-threatening emergency that can initially present to ophthalmologists. One should suspect EKPE in septic patients with a B-scan showing a vitreous or retinal abscess.

Endogenous Endophthalmitis in the American and Korean Population: An 8-year Retrospective Study

PURPOSE

To study the clinical features of endogenous endophthalmitis (EE) in sample patient populations from the USA and South Korea over an 8-year period.

METHODS

We reviewed data from 128 eyes of 60 American and 48 Korean patients diagnosed with EE and compared their clinical characteristics.

RESULTS

Fungemia and liver abscess were the most common extraocular infection sources among American (26.7%) and Korean patients (33.3%), respectively. Klebsiella pneumoniae and Candida species were the most common pathogens of EE in the Korean and the American patients, respectively. Endophthalmitis caused by fungi had a better visual prognosis than that caused by bacteria (p = 0.001). Vitrectomy was beneficial for eyes with EE due to virulent bacteria presenting with worse than counting finger vision.

CONCLUSIONS

The predisposing conditions and responsible organisms for EE vary in different regions of the world. The visual prognosis was strongly influenced by the underlying pathogen.

Endogenous endophthalmitis with a visual acuity of 6/6

A 43-year-old man suffering from Klebsiella liver abscess and bacteraemia presented with left eye visual disturbance a few days after admission. His visual acuity was 6/6. There was a whitish subretinal mass located at the temporal periphery without vitritis. His visual acuity dropped to 6/120 with marked vitritis 1 day later and a diagnosis of a subretinal abscess was made. The vitreous cultures were negative. Response was suboptimal with intravitreal antibiotics, and retinotomy, vitrectomy, antibiotic irrigation and silicone oil tamponade were required. His vision gradually improved to 6/60 with silicone oil in situ. This case illustrates the rare presentation of a subretinal abscess in endogenous endophthalmitis with no initial associated vitritis, and the importance of maintaining a high level of suspicion despite good visual acuity on presentation in cases with relevant history. Early detection and intervention, and close monitoring may salvage the patient's vision in such cases.

Endophthalmitis caused by Klebsiella species

PURPOSE

To report the clinical presentation, antibiotic sensitivities, treatment strategies, and visual outcomes associated with endophthalmitis caused by Klebsiella species.

METHODS

A noncomparative consecutive case series. Microbiology database records were retrospectively reviewed for all patients with endophthalmitis caused by Klebsiella species from 1990 to 2012 at a large university referral center. The corresponding clinical records were then reviewed to evaluate the endophthalmitis clinical features and treatment outcomes.

RESULTS

Seven patients were identified. Clinical settings included endogenous (n = 3), posttraumatic (n = 2), trabeculectomy bleb-associated (n = 1), and postpenetrating keratoplasty (n = 1). Five patients presented with hypopyon. Presenting visual acuity ranged from 20/60 to light perception in nonendogenous cases and 1/200 to light perception in endogenous cases. Klebsiella was sensitive to aminoglycosides, third-generation cephalosporins, and second- and third-generation fluoroquinolones in all cases. Initial treatment strategies were vitreous tap and injection (n = 4), pars plana vitrectomy with intravitreal antibiotics (n = 2), and anterior chamber tap and injection (n = 1). All three endogenous cases later underwent enucleation or evisceration. In nonendogenous cases, the final visual acuity was 20/70 or better in all 4 patients.

CONCLUSION

Endophthalmitis caused by Klebsiella species is associated with poor visual outcomes. Endogenous cases had high rates of enucleation or evisceration.

An eleven-year retrospective study of endogenous bacterial endophthalmitis

Purpose. To determine the clinical features, microbial profiles, treatment outcomes, and prognostic factors for endogenous bacterial endophthalmitis (EBE). Methods. The medical records of 27 eyes of 21 patients diagnosed with EBE for 11 years were reviewed. Collected data included age, site of infection, visual acuities (VAs), microbial profiles, and treatment regimen. Results. The mean age was 68.5 years. Gram-positive organisms accounted for 76.2%, while gram-negative ones accounted for 19.0%. Staphylococcus aureus was the most common causative organism (52.3%) of which 72.7% was methicillin-resistant S. aureus. A final VA of ≥20/40 was achieved in 44% and 20/200 or better was in 64%. Eyes with initial VA of ≥20/200 (P = 0.003) and focal involvements (P = 0.011) had significantly better final VA. Initial VA (P = 0.001) and the interval between onset of ocular symptoms and intravitreal antibiotic injection (P = 0.097) were associated with final VA in eyes receiving intravitreal antibiotics. Conclusions. EBE is generally associated with poor visual outcome; however the prognosis may depend on initial VA, extent of ocular involvement, and an interval between onset of ocular symptoms and intravitreal antibiotic injection. Early diagnosis and early intravitreal injection supplement to systemic antibiotics might lead to a relatively good visual outcome.

A lack of ongoing diabetes is an important factor in preserving eyes from late or suboptimally treated endogenous endophthalmitis secondary to Klebsiella pneumoniae liver abscess

Purpose:

The purpose of this study is to identify the possible factors for preserving the eyes after late or suboptimally treated endogenous endophthalmitis secondary to Klebsiella pneumoniae (KP) liver abscess.

Methods:

A retrospective chart review was conducted for patients admitted with KP liver abscess from January 1991 to June 2012.

Results:

Six hundred and ninety-three patients with KP liver abscess were recorded, in which endophthalmitis was identified in 53 cases (65 eyes, 8.29%). Diabetes was significantly associated with the development of endophthalmitis (p = 0.014). Eleven eyes received their last ocular treatment ≥10 days and final vision ≥ counting fingers, and were defined as benign type KP endophthalmitis. The absence of diabetes was the only consistent candidate factor for benign type KP endophthalmitis.

Conclusion:

A lack of ongoing diabetes is an important factor in preserving eyes with late or suboptimally treated endogenous endophthalmitis second to KP liver abscess.

Klebsiella pneumonia-induced prostate abscess: How to work it up?

INTRODUCTON

Klebsiella pneumonia (KP) is related to a metastatic phenomenon from the originally affected primary organ. About 28% of patients with pyogenic liver abscess arising from KP suffer from metastatic complications. This study was done to define the clinical features of KP-induced prostate abscess.

METHODS

A total of 14 patients were diagnosed with prostate abscess based on clinical, laboratory examination and abdominopelvic computed tomography (CT) scan from 2007 to 2013.

RESULTS

Among these 14 patients, KP was the dominant causative microorganism in 6 patients (42.9%), followed by Esherchia coli in 2, Pseudomonas aeroginosa in 1, methicillin-resistant Staphyolcoccus aureus in 1, and no growth in either the urine or blood culture in 4. Four (66.7%) of the 6 KP induced-prostate abscess had other concurrent abscess sites besides the prostate: liver in 3, kidney in 1, and perianal area with endogenous endophthalmitis that ended in loss of vision in 1 patient.

CONCLUSIONS

We report on the clinical features of KP-induced prostate abscess based on a small number of patients, which is the main limitation of our study. We believe that if the causative organism of a prostate abscess was KP, more workup would be needed to rule out the presence of an abscess in other organs, especially in the liver. Abdominopelvic CT scan would be a proper imaging modality.

Update on the prevention and treatment of endophthalmitis

Endophthalmitis remains a rare but serious cause of visual loss. Over time, changes have been noted in endophthalmitis in terms of predominant causes, infecting organisms, and antibiotic susceptibilities. There is controversy regarding the use of intracameral prophylactic antimicrobials during cataract surgery. Alternatively, there appears to be increasing evidence against using routine topical antibiotics for intravitreal injections. There are also increasing reports of multidrug-resistant organisms causing endophthalmitis, but the combination of vancomycin and ceftazidime appears effective for the vast majority of cases. Future trends may involve increasing utilization of polymerase chain reaction for diagnosis, and possibly office-based pars plana vitrectomy for treatment of endophthalmitis.

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.

Endogenous Klebsiella pneumoniae endophthalmitis

Klebsiella pneumonia is a common human pathogen, and endogenous endophthalmitis is a vision-threatening infection presentedwith pain, redness, decreased vision acuity, and intraocular inflammation. Endogenous endophthalmitis caused by Klebsiella pneumoniae is uncommon and usually happens in patients with immunosuppression conditions. Diabetes is a predisposing risk factor, and liver abscess is a major source of Klebsiella pneumonia endogenous endophthalmitis (KPEE). Here, we report a case of KPEE in a patient who lost his vision in one eye after treatment.

Aerobactin mediates virulence and accounts for increased siderophore production under iron-limiting conditions by hypervirulent (hypermucoviscous) Klebsiella pneumoniae

Hypervirulent (hypermucoviscous) Klebsiella pneumoniae (hvKP) strains are an emerging variant of "classical" K. pneumoniae (cKP) that cause organ and life-threatening infection in healthy individuals. An understanding of hvKP-specific virulence mechanisms that enabled evolution from cKP is limited. Observations by our group and previously published molecular epidemiologic data led us to hypothesize that hvKP strains produced more siderophores than cKP strains and that this trait enhanced hvKP virulence. Quantitative analysis of 12 hvKP strains in iron-poor minimal medium or human ascites fluid showed a significant and distinguishing 6- to 10-fold increase in siderophore production compared to that for 14 cKP strains. Surprisingly, high-pressure liquid chromatography (HPLC)-mass spectrometry and characterization of the hvKP strains hvKP1, A1142, and A1365 and their isogenic aerobactin-deficient (ΔiucA) derivatives established that aerobactin accounted for the overwhelming majority of increased siderophore production and that this was not due to gene copy number. Further, aerobactin was the primary factor in conditioned medium that enhanced the growth/survival of hvKP1 in human ascites fluid. Importantly the ex vivo growth/survival of hvKP1 ΔiucA was significantly less than that of hvKP1 in human ascites fluid, and the survival of outbred CD1 mice challenged subcutaneously or intraperitoneally with hvKP1 was significantly less than that of mice challenged with hvKP1 ΔiucA. The lowest subcutaneous and intraperitoneal challenge inocula of 3 × 10(2) and 3.2 × 10(1) CFU, respectively, resulted in 100% mortality, demonstrating the virulence of hvKP1 and its ability to cause infection at a low dose. These data strongly support that aerobactin accounts for increased siderophore production in hvKP compared to cKP (a potential defining trait) and is an important virulence factor.

An Increasing Prominent Disease of Klebsiella pneumoniae Liver Abscess: Etiology, Diagnosis, and Treatment

Background. During the past two decades, Klebsiella pneumoniae (K. pneumoniae) had surpassed Escherichia coli (E. coli) as the predominant isolate from patients with pyogenic liver abscess (PLA) in Asian countries, the United States, and Europe, and it tended to spread globally. Since the clinical symptom is atypical, the accurate and effective diagnosis and treatment of K. pneumoniae liver abscesses (KLAs) are very necessary. Methods. Here, we have comprehensively clarified the epidemiology and pathogenesis of KLA, put emphases on the clinical presentations especially the characteristic radiographic findings of KLA, and thoroughly elucidated the most effective antibiotic strategy of KLA. Results. K1 serotype is strongly associated with KLA especially in diabetic patients. Computed tomography (CT) and ultrasound (US) were two main diagnostic methods of KLA in the past. Most of KLAs have solitary, septal lobular abscesses in the right lobe of liver, and they are mainly monomicrobial. Broad-spectrum antibiotics combined with the US-guided percutaneous drainage of liver abscesses can increase their survival rates, but surgical intervention still has its irreplaceable position. Conclusion. The imaging features contribute to the early diagnosis, and the percutaneous intervention combined with an aminoglycoside plus either an extended-spectrum betalactam or a second- or third-generation cephalosporin is a timely and effective treatment of KLA.