Kingella kingae Osteoarticular Infections Approached through the Prism of the Pediatric Orthopedist

Nowadays, Kingella kingae (K. kingae) is considered as the main bacterial cause of osteoarticular infections (OAI) in children aged less than 48 months. Next to classical acute hematogenous osteomyelitis and septic arthritis, invasive K. kingae infections can also give rise to atypical osteoarticular infections, such as cellulitis, pyomyositis, bursitis, or tendon sheath infections. Clinically, K. kingae OAI are usually characterized by a mild clinical presentation and by a modest biologic inflammatory response to infection. Most of the time, children with skeletal system infections due to K. kingae would not require invasive surgical procedures, except maybe for excluding pyogenic germs’ implication. In addition, K. kingae’s OAI respond well even to short antibiotics treatments, and, therefore, the management of these infections requires only short hospitalization, and most of the patients can then be treated safely as outpatients.

Proinflammatory Microenvironment During Kingella kingae Infection Modulates Osteoclastogenesis

Kingella kingae is an emerging pathogen that causes septic arthritis, osteomyelitis, and bacteremia in children from 6 to 48 months of age. The presence of bacteria within or near the bone is associated with an inflammatory process that results in osteolysis, but the underlying pathogenic mechanisms involved are largely unknown. To determine the link between K. kingae and bone loss, we have assessed whether infection per se or through the genesis of a pro-inflammatory microenvironment can promote osteoclastogenesis. For that purpose, we examined both the direct effect of K. kingae and the immune-mediated mechanism involved in K. kingae-infected macrophage-induced osteoclastogenesis. Our results indicate that osteoclastogenesis is stimulated by K. kingae infection directly and indirectly by fueling a potent pro-inflammatory response that drives macrophages to undergo functional osteoclasts via TNF-α and IL-1β induction. Such osteoclastogenic capability of K. kingae is counteracted by their outer membrane vesicles (OMV) in a concentration-dependent manner. In conclusion, this model allowed elucidating the interplay between the K. kingae and their OMV to modulate osteoclastogenesis from exposed macrophages, thus contributing to the modulation in joint and bone damage.

Enigma of Respiratory Carriage of Kingella kingae and Neisseria meningitides in Young Jordanian Children

Background: Kingella kingae and Neisseria meningitides are gram-negative bacteria, causing several life-threatening diseases and considered as opportunistic pathogens in the upper respiratory tract of healthy carriers. The detection of these both bacteria species is difficult in routine culture methods. Objective: This study aimed to find the occurrence rate of K. kingae and N. meningitides colonizing upper respiratory tract of young Jordanian children, and to determine the antimicrobial susceptibility profile of the isolates. Methods: A total of 300 samples of throat and nasal swabs were collected from out- patients Jordanian children aged between 6 months and 5 years, who were admitted to Pediatrics' clinics department at the Jordan University Hospital and Al-Bashir Hospital over the period October 2018 through January 2019. Samples were cultured for detection K. kingae and Neisseria species including specially N. meningitides. Their suspected growth was identified and tested using microbiology culture methods and polymerase chain reaction (PCR) method. Additionally, DNA was extracted directly from one 100 samples and was investigated only for K. kingae using real- time PCR assay. Results: This study showed the absence of K. kingae in all cultured samples, while Neisseriaspecies was detected in 21 (7 %)including one N. meningitides isolate(0.3%). The results of antibiotic susceptibility testing indicated presence of few percentage of Neisseria species isolates resistant 100 % to clindamycin, oxacillin and vancomycin, whereas all were susceptible for chloramphenicol (100%)levofloxacin and gentamycin , and less to ampicillin(90.6%) and erytromycin ( 85.7%), respectively. Conclusion: This study shows the absence of K. kingae and the rare occurrence of N. meningitides colonizing the upper respiratory tract of young Jordanian children over the 4-month period of study.

Native joint infections in Iceland 2003–2017: an increase in postarthroscopic infections

ObjectivesNationwide study on the epidemiology, clinical characteristics and outcomes among patients with native joint infection (NJI) in Iceland, 2003–2017.MethodsAll positive synovial fluid culture results in Iceland were identified and medical records reviewed.ResultsA total of 299 NJI (40 children and 259 adults) were diagnosed in Iceland in 2003–2017, with a stable incidence of 6.3 cases/100 000/year, but marked gender difference among adults (33% women vs 67% men, p<0.001). The knee joint was most commonly affected, and Staphylococcus aureus was the most common isolate in both adults and children, followed by various streptococcal species in adults and Kingella kingae in children. NJI was iatrogenic in 34% of adults (88/259) but comprised 45% among 18–65 years and a stable incidence. Incidence of infections following arthroscopic procedures in adults increased significantly compared with the previous decade (9/100 000/year in 1990–2002 vs 25/100 000/year in 2003–2017, p<0.01) with no significant increase seen in risk per procedure. The proportion of postarthroscopic NJI was 0.17% overall but 0.24% for knee arthroscopy. Patients with postarthroscopic infection were more likely to undergo subsequent arthroplasty when compared with other patients with NJI (p=0.008).ConclusionsThe incidence of NJI in Iceland has remained stable. The proportion of iatrogenic infections is high, especially among young adults, with an increase seen in postarthroscopic infections when compared with the previous decade. Although rare, NJI following arthroscopy can be a devastating complication, with significant morbidity and these results, therefore, emphasise the need for firm indications when arthroscopic treatment is considered.

Fulminant Infective Endocarditis Due to Kingella Kingae and Several Complications in a 6-Year-Old Girl: A Case Report

Kingella kingae is a gram-negative coccobacillus belonging to the HACEK group (Haemophilus species, Aggregatibacter actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella species) and is a common oropharyngeal colonizer of healthy young children. Osteoarticular infection is the most commonly reported invasive Kingella kingae infection in children, usually presenting a mild clinical picture. However, it can also cause severe invasive infections, especially infective endocarditis, with a high complication rate. We report the case of a 6-year-old girl, with no past medical history, who presented with fulminant infective endocarditis due to Kingella kingae. She received emergency venoarterial extracorporeal membrane oxygenation support, rapidly underwent cardiac surgery, and was then treated using ceftriaxone for 4 weeks as recommended by the American Heart Association. The patient's postoperative course was marked by a cerebral ischemic stroke consistent with septic embolism. She also presented with a para-aortic pseudoaneurysm that required a secondary surgical procedure, with a good postoperative result. This report illustrates a case of fulminant infective endocarditis due to Kingella kingae and responsible for two major complications. We also describe the preventive valve surgery performed to ensure the preservation of valve function and its capacity for growth.