Phylogenomic analysis of the understudied Neisseriaceae species reveals a poly- and paraphyletic Kingella genus.

IMPORTANCE: Understanding the evolutionary relationships between the species in the Neisseriaceae family has been a persistent challenge in bacterial systematics due to high recombination rates in these species. Previous studies of this family have focused on Neisseria meningitidis and N. gonorrhoeae. However, previously understudied Neisseriaceae species are gaining new attention, with Kingella kingae now recognized as a common human pathogen and with Alysiella and Simonsiella being unique in the bacterial world as multicellular organisms. A better understanding of the genomic evolution of the Neisseriaceae can lead to the identification of specific genes and traits that underlie the remarkable diversity of this family.

Oral Dysbiosis and Inflammation in Parkinson's Disease.

BACKGROUND: Oral microbiota has largely escaped attention in Parkinson's disease (PD), despite its pivotal role in maintaining oral and systemic health. OBJECTIVE: The aim of our study was to examine the composition of the oral microbiota and the degree of oral inflammation in PD. METHODS: Twenty PD patients were compared to 20 healthy controls. Neurological, periodontal and dental examinations were performed as well as dental scaling and gingival crevicular fluid sampling for cytokines measurement (interleukine (IL)-1ß, IL-6, IL-1 receptor antagonist (RA), interferon-γ and tumor necrosis factor (TNF)-α). Two months later, oral microbiota was sampled from saliva and subgingival dental plaque. A 16S rRNA gene amplicon sequencing was used to assess bacterial communities. RESULTS: PD patients were in the early and mid-stage phases of their disease (Hoehn & Yahr 2-2.5). Dental and periodontal parameters did not differ between groups. The levels of IL-1ß and IL-1RA were significantly increased in patients compared to controls with a trend for an increased level of TNF-α in patients. Both saliva and subgingival dental plaque microbiota differed between patients and controls. Streptococcus mutans, Kingella oralis, Actinomyces AFQC_s, Veillonella AFUJ_s, Scardovia, Lactobacillaceae, Negativicutes and Firmicutes were more abundant in patients, whereas Treponema KE332528_s, Lachnospiraceae AM420052_s, and phylum SR1 were less abundant. CONCLUSION: Our findings show that the oral microbiome is altered in early and mid-stage PD. Although PD patients had good dental and periodontal status, local inflammation was already present in the oral cavity. The relationship between oral dysbiosis, inflammation and the pathogenesis of PD requires further study.

HACEK infective endocarditis: Epidemiology, clinical features, and outcome: A case-control study.

OBJECTIVES: The study aimed to describe the epidemiological, microbiological, and clinical features of a population sample of 17 patients with HACEK infective endocarditis (HACEK-IE) and to compare them with matched control patients with IE caused by viridans group streptococci (VGS-IE). METHODS: Cases of definite (n=14, 82.2%) and possible (n=3, 17.6%) HACEK-IE included in the Infective Endocarditis Hospital Clinic of Barcelona (IE-HCB) database between 1979 and 2016 were identified and described. Furthermore, a retrospective case-control analysis was performed, matching each case to three control subjects with VGS-IE registered in the same database during the same time period. RESULTS: Seventeen out of 1209 IE cases (1.3%, 95% confidence interval 0.69-1.91%) were due to HACEK group organisms. The most frequently isolated HACEK species were Aggregatibacter spp (n=11, 64.7%). Intracardiac vegetations were present in 70.6% of cases. Left heart failure (LHF) was present in 29.4% of cases. Ten patients (58.8%) required in-hospital surgery and none died during hospitalization. In the case-control analysis, there was a trend towards larger vegetations in the HACEK-IE group (median (interquartile range) size 11.5 (10.0-20.0) mm vs. 9.0 (7.0-13.0) mm; p=0.068). Clinical manifestations, echocardiographic findings, LHF rate, systemic emboli, and other complications were all comparable (p>0.05). In-hospital surgery and mortality were similar in the two groups. One-year mortality was lower for HACEK-IE (1/17 vs. to 6/48; p=0.006). CONCLUSIONS: HACEK-IE represented 1.3% of all IE cases. Clinical features and outcomes were comparable to those of the VGS-IE control group. Despite the trend towards a larger vegetation size, the embolic event rate was not higher and the 1-year mortality was significantly lower for HACEK-IE.

[Bacteremia due to Kingella denitrificans in a child followed-up for bone marrow failure syndrome]. / Bactériémie à Kingella denitrificans chez un enfant suivi pour un syndrome d'insuffisance médullaire.

Kingella denitrificans is a non-pathogenic micro-organism present in oropharyngeal flora. This germ has been recently recognized as responsible for opportunistic invasive infections mainly affecting immunosuppressed patients. We here report the case of a child aged 3 years and 7 months followed-up since the age of one year for bone marrow failure syndrome associated with pancytopenia of undetermined origin who had bacteremia due to Kingella denitrificans, a group of difficult to culture gram-negative bacteria rarely described in the literature. Clinicians and microbiologists should suspect the presence of this germ especially in immunosuppressed patients. The use of blood culture bottle contributes in a significant way to the detection of this germ.

Colonization of an acid resistant Kingella denitrificans in the stomach may contribute to gastric dysbiosis by Helicobacter pylori.

In the stomach of a gastric ulcer patient who had been administered an anti-acid, a gram-negative and urease-negative bacillus similar in size to Helicobacter pylori was infected together with H. pylori. According to biochemical test and 16S rRNA gene analysis, the urease-negative bacterium was identified as Kingella denitrificans, a human nasopharyngeal commensal. In contrast to the standard strain of K. denitrificans, the isolate showed catalase activity, did not produce acid from glucose, and exhibited acid tolerance. Acid tolerance of H. pylori was increased by cocultivation with the K. denitrificans isolate, but not with other isolates of K. denitrificans. Disruption of physiological and immunological niche by dysbiotic colonization of bacterium may provide pathological attributes to human stomach. Collectively, a careful administration of anti-acids to the elderly, especially those with atrophic gastritis, is necessary to avoid repression of the gastric barrier to bacteria.

HACEK infective endocarditis: characteristics and outcomes from a large, multi-national cohort.

The HACEK organisms (Haemophilus species, Aggregatibacter species, Cardiobacterium hominis, Eikenella corrodens, and Kingella species) are rare causes of infective endocarditis (IE). The objective of this study is to describe the clinical characteristics and outcomes of patients with HACEK endocarditis (HE) in a large multi-national cohort. Patients hospitalized with definite or possible infective endocarditis by the International Collaboration on Endocarditis Prospective Cohort Study in 64 hospitals from 28 countries were included and characteristics of HE patients compared with IE due to other pathogens. Of 5591 patients enrolled, 77 (1.4%) had HE. HE was associated with a younger age (47 vs. 61 years; p<0.001), a higher prevalence of immunologic/vascular manifestations (32% vs. 20%; p<0.008) and stroke (25% vs. 17% p = 0.05) but a lower prevalence of congestive heart failure (15% vs. 30%; p = 0.004), death in-hospital (4% vs. 18%; p = 0.001) or after 1 year follow-up (6% vs. 20%; p = 0.01) than IE due to other pathogens (n = 5514). On multivariable analysis, stroke was associated with mitral valve vegetations (OR 3.60; CI 1.34-9.65; p<0.01) and younger age (OR 0.62; CI 0.49-0.90; p<0.01). The overall outcome of HE was excellent with the in-hospital mortality (4%) significantly better than for non-HE (18%; p<0.001). Prosthetic valve endocarditis was more common in HE (35%) than non-HE (24%). The outcome of prosthetic valve and native valve HE was excellent whether treated medically or with surgery. Current treatment is very successful for the management of both native valve prosthetic valve HE but further studies are needed to determine why HE has a predilection for younger people and to cause stroke. The small number of patients and observational design limit inferences on treatment strategies. Self selection of study sites limits epidemiological inferences.

Retropharyngeal abscess from an unusual organism-Kingella denitrificans-in a patient on low-dose methotrexate.

Retropharyngeal abscess can be a life-threatening emergency with potential for airway compromise. We report a case of retropharyngeal abscess caused by Kingella denitrificans in a 66-year-old Caucasian man taking low-dose methotrexate for psoriatic arthritis. K denitrificans has not been previously reported as a cause of retropharyngeal abscess. K denitrificans, along with other Kingella species, is often found to be part of the normal upper respiratory tract flora. Potentially life-threatening complications of retropharyngeal abscess can occur in immunocompromised patients. Although complications of immunosuppression are thought to be rare with the use of low-dose pulse methotrexate for non-neoplastic conditions, such complications with prolonged use of low-dose pulse methotrexate may be seen.

Isolation of Kingella denitrificans from a corneal ulcer.

PURPOSE: To report a case of a corneal ulcer caused by an unusual pathogen. DESIGN: Case report. METHODS: Clinical review describing initial presentation, course, and outcome of 1 patient with a corneal ulcer caused by Kingella denitrificans. RESULTS: A 77-year-old man with a prior history of 4 penetrating keratoplasties in the right eye for herpes simplex virus keratitis presented with a 3-day history of a red painful right eye. On examination, he was found to have a corneal ulcer identified by culture as K. denitrificans. CONCLUSIONS: Although Kingella spp. is not a common ocular pathogen, it can infect the cornea, especially when the host immune defense is altered.

Endocarditis after closure of ventricular septal defect by transcatheter device.

Advances in interventional cardiology have enabled the treatment of severe congenital heart defects without the need for surgery. The percutaneous closure of atrial septal defects and, more recently, ventricular septal defects is considered a safe procedure with fewer complications and less morbidity compared with surgery. We report on a 2-year-old child who developed endocarditis after ventricular septal defect closure with an Amplatzer device. The patient recovered after intravenous antibiotics and anticoagulation. To the best of our knowledge, this is the first report of endocarditis associated with ventricular septal defect closure device insertion.

[Prosthetic endocarditis caused by Kingella denitrificans in a patient with diabetes mellitus].

Infective endocarditis caused by Kingella denitrificans occurs rarely. A review of the literature reveals only 6 cases of endocarditis caused by the bacillus. K. denitrificans is normally a commensal of the upper respiratory airways, may exceptionally be responsible for endocarditis. A case of possible prosthetic endocarditis caused by K. denitrificans is presented. A 78-year-old male with Type II diabetes was admitted to the hospital complaining of fever, a sore throat and arthralgia. He underwent replacement surgery of a St. Jude medical prosthesis for aortic stenosis at the age of 75. The only physical findings at admission were a temperature of 38.2 degrees C and murmurs of mild mitral regurgitation. The liver and spleen were not palpable, and there were no skin or eye lesions. Laboratory findings were as follows: white blood cell count 9500/microliters with 77% neutrophils, erythrocyte sedimentation rate 71 mm/h (Westergren), blood urea nitrogen 50.2 mg/dl, serum creatinine 1.7 mg/dl and C-reactive protein 22.2 mg/dl. The Gram-negative bacillus isolated from the blood was identified as K. denitrificans by the identification system, namely ID test.FN-20 rapid (Nissui, Japan). Although an echocardiogram detected no vegetation, infective endocarditis was diagnosed because the same bacillus was detected by separate blood cultures and an obvious source of infection was not found other than the prosthetic valve. Initial treatment was flomoxef, which was changed to Ampicillin 2 g/day after K. denitrificans was identified. Ampicillin continued for 6 weeks. The clinical course was good and he did not require further surgery. He has been afebrile for 2 years after completing treatment. This case represents the first report of prosthetic valve endocarditis caused by K. denitrificans in Japan.

Endocarditis caused by Kingella denitrificans.

We report the case of a 48-year-old man with native valve endocarditis caused by Kingella denitrificans. He was successfully treated with a combination of beta-lactam antibiotics and aminoglycosides, after which he underwent valve replacement surgery. This case represents the first report in the literature of elective native valve replacement. Previously reported cases are discussed together with management options, including suggestions for the treatment of patients with beta-lactam allergy and those infected with beta-lactamase producing strains.