Clinical and Biologic Characteristics of Kingella kingae -Induced Septic Arthritis of the Knee in Young Children.

BACKGROUND AND OBJECTIVES: Septic arthritis of the knee is presumed to be the most frequent form of Kingella kingae -induced osteoarticular infection. This study aimed to report on the clinical course, biological parameters, and results of microbiological investigations among children with K. kingae -induced septic arthritis of the knee. It also assessed the modified Kocher-Caird criteria's ability to predict K. kingae -induced septic arthritis of the knee. METHODS: The medical charts of 51 children below 4 years old with confirmed or highly probable K. kingae -induced arthritis of the knee were reviewed. Data were gathered on the five variables in the commonly-used Kocher-Caird prediction algorithm (body temperature, refusal to bear weight, leukocytosis, erythrocyte sedimentation rate, and C-reactive protein level). RESULTS: Patients with K. kingae -induced arthritis of the knee usually presented with a mildly abnormal clinical picture and normal or near-normal serum levels of acute-phase reactants. Data on all five variables were available for all the children: 7 children had zero predictors; 8, 20, 12, and 4 children had 1, 2, 3, and 4 predictors, respectively; no children had 5 predictors. This gave an average of 1.96 predictive factors and a subsequent probability of ≤ 62.4% of infectious arthritis in this pediatric cohort. CONCLUSIONS: Because the clinical features of K. kingae -induced arthritis of the knee overlap with many other conditions affecting this joint, the Kocher-Caird prediction algorithm is not sensitive enough to effectively detect K. kingae -induced septic arthritis of the knee. Excluding K. kingae -induced arthritis of the knee requires performing nucleic acid amplification assays on oropharyngeal swabs and joint fluid from those young children presenting with effusion of the knee, even in the absence of fever, leukocytosis, or a high Kocher-Caird score.

The Kingella kingae PilC1 MIDAS Motif Is Essential for Type IV Pilus Adhesive Activity and Twitching Motility.

Kingella kingae is an emerging pathogen that has recently been identified as a leading cause of osteoarticular infections in young children. Colonization with K. kingae is common, with approximately 10% of young children carrying this organism in the oropharynx at any given time. Adherence to epithelial cells represents the first step in K. kingae colonization of the oropharynx, a prerequisite for invasive disease. Type IV pili and the pilus-associated PilC1 and PilC2 proteins have been shown to mediate K. kingae adherence to epithelial cells, but the molecular mechanism of this adhesion has remained unknown. Metal ion-dependent adhesion site (MIDAS) motifs are commonly found in integrins, where they function to promote an adhesive interaction with a ligand. In this study, we identified a potential MIDAS motif in K. kingae PilC1 which we hypothesized was directly involved in mediating type IV pilus adhesive interactions. We found that the K. kingae PilC1 MIDAS motif was required for bacterial adherence to epithelial cell monolayers and extracellular matrix proteins and for twitching motility. Our results demonstrate that K. kingae has co-opted a eukaryotic adhesive motif for promoting adherence to host structures and facilitating colonization.

Surface Anchoring of the Kingella kingae Galactan Is Dependent on the Lipopolysaccharide O-Antigen.

Kingella kingae is a leading cause of bone and joint infections and other invasive diseases in young children. A key K. kingae virulence determinant is a secreted exopolysaccharide that mediates resistance to serum complement and neutrophils and is required for full pathogenicity. The K. kingae exopolysaccharide is a galactofuranose homopolymer called galactan and is encoded by the pamABC genes in the pamABCDE locus. In this study, we sought to define the mechanism by which galactan is tethered on the bacterial surface, a prerequisite for mediating evasion of host immune mechanisms. We found that the pamD and pamE genes encode glycosyltransferases and are required for synthesis of an atypical lipopolysaccharide (LPS) O-antigen. The LPS O-antigen in turn is required for anchoring of galactan, a novel mechanism for association of an exopolysaccharide with the bacterial surface. IMPORTANCE Kingella kingae is an emerging pediatric pathogen and produces invasive disease by colonizing the oropharynx, invading the bloodstream, and disseminating to distant sites. This organism produces a uniquely multifunctional exopolysaccharide called galactan that is critical for virulence and promotes intravascular survival by mediating resistance to serum and neutrophils. In this study, we established that at least some galactan is anchored to the bacterial surface via a novel structural interaction with an atypical lipopolysaccharide O-antigen. Additionally, we demonstrated that the atypical O-antigen is synthesized by the products of the pamD and pamE genes, located downstream of the gene cluster responsible for galactan biosynthesis. This work addresses how the K. kingae exopolysaccharide can mediate innate immune resistance and advances understanding of bacterial exopolysaccharides and lipopolysaccharides.

First report of Kingella kingae infection in a paediatric population in Accra, Ghana.

Introduction: Kingella kingae is recognized as a frequent source of childhood bacteremia and the commonest agent of skeletal system infections in children 6 months - 4 years old. Several factors, including difficulty in detecting this fastidious organism in routine laboratory assays, result in underdiagnosis of the infections. Species-specific nucleic acid amplification assays, however, significantly improve the detection of K. kingae in blood samples. The aim of this study was to detect K. kingae infection in young children in Accra, Ghana. Methods: a cross-sectional based study was carried out in three hospitals in Accra. Children with febrile illness and directed by a clinician for blood culture were recruited. Blood samples collected were analysed by culture and polymerase chain reaction (PCR), using universal prokaryotic and K. kingae rtxA primers. Results: blood samples from 232 children (mean age 20.10 ± 12.57 months) were analysed. Bacteremia (72.4%) was the highest clinical diagnosis particularly in the 12-24 months age group. Only 7 (3.1%) samples showed bacterial growth and were negative for Kingella. PCR with universal prokaryotic primers succeeded in 223 (96.1%) out of 232 samples. PCR with K. kingae rtxA toxin primers was positive for 12 (5.4%) samples, all diagnosed as bacteremia, out of the 223 samples. Eleven (91.7%) out of the 12 K. kingae PCR positives were culture-negative. Conclusion: Kingella kingae was detected only by PCR specific for the K. kingae rtxA toxin. Kingella kingae may be a potential cause of bacteremia and hence febrile illness in young children living in Accra, Ghana.

First documented outbreak of arthritis caused by Kingella kingae in a Spanish childcare center.

BACKGROUND: Recently, Kingella kingae (K. kingae) has been described as the most common agent of skeletal system infections in children 6 months-2 years of age. More exceptional is the clinical presentation in clusters of invasive K. kingae infections. We describe the investigation of the first outbreak of 3 cases of arthritis caused by K. kingae documented in Spain detected in a daycare center in Roses, Girona. PATIENTS AND METHODS: In December of 2015 surveillance throat swabs obtained from all attendees from the same class of the index daycare center were assessed to study the prevalence of K. kingae colonization. The sample was composed of 9 toddlers (range: 16-23 months of age). Investigation was performed by culture and K. kingae-specific RT-PCR. Combined amoxicillin-rifampicin prophylaxis was offered to all attendees who were colonized by K. kingae. Following antimicrobial prophylaxis, a new throat swab was taken to confirm bacterial eradication. RESULTS: K. kingae was detected by RT-PCR throat swabs in the 3 index cases and 5 of the 6 daycare attendees. Cultures were negative in all cases. After administration of prophylactic antibiotics, 3 toddlers were still positive for K. kingae-specific RT-PCR. CONCLUSIONS: Clusters of invasive K. kingae infections can occur in daycare facilities and closed communities. Increased awareness and use of sensitive detection methods are needed to identify and adequately investigate outbreaks of K. kingae disease. In our experience, the administration of prophylactic antibiotics could result in partial eradication of colonization. No further cases of disease were detected after prophylaxis.

Kingella kingae Spondylodiscitis: Treatment Failure With Flucloxacillin.

Kingella kingae infections generally respond well to most beta-lactam antibiotics. We investigated an antibiotic treatment failure in a 3-year-old with K. kingae L3-4 spondylodiscitis. Her disease progressed even after 19 days of high-dose intravenous flucloxacillin. The clinical isolate did not produce a beta-lactamase and despite phenotypic testing and whole-genome sequencing, the mechanism of flucloxacillin resistance remains unknown.

Native joint infections in Iceland 2003-2017: an increase in postarthroscopic infections.

OBJECTIVES: Nationwide study on the epidemiology, clinical characteristics and outcomes among patients with native joint infection (NJI) in Iceland, 2003-2017. METHODS: All positive synovial fluid culture results in Iceland were identified and medical records reviewed. RESULTS: A 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). CONCLUSIONS: The 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.

The effects of periodontitis associated microbiota on the development of oral squamous cell carcinoma.

Epidemiological data have shown that periodontal bacterial infection, periodontitis, and oral squamous cell carcinoma have close relationship on the disease progress and risk. However, the specific role of periodontal microbes and their mechanism in the development of oral squamous cell carcinoma is not yet clear. In our previous work, metagenomic Illumina Mi-seq analysis was used to identify tstructure and abundance of periodontital microbiome. Accoding to the results, we used Porphyromonas.spp. and Fusobacterium.spp. as the periodontitis positive microbiota; Neisseria.spp and Corynebacterium.spp as periodontitis negative microbiota (their average relative abundance were >5%). These representative strains of the above genus were used to infect OSCC cells to explore their effect on tumor cell biology behavior, and detect the expression level of the gene in related to inflammation, migration, invasion and cell cycle. We find that periodontitis positive correlated microbiota had a promoting effect on the development of oral squamous cell carcinoma in vitro by regulating mRNA and protein expression of IL-6, IL-8, MMP-9 and Cyclin-D1. Periodontitis negative correlated microbiota had suppression effect on the development of oral squamous cell carcinoma in vitro analysis.

Kingella kingae Displaced S. aureus as the Most Common Cause of Acute Septic Arthritis in Children of All Ages.

BACKGROUND: Acute septic arthritis (SA) still remains a challenge with significant worldwide morbidity. In recent years, Kingella kingae has emerged and treatment regimens have become shorter. We aim to analyze trends in SA etiology and management and to identify risk factors for complications. METHODS: Longitudinal observational, single center study of children (<18 years old) with SA admitted to a tertiary care pediatric hospital, from 2003 to 2018, in 2 cohorts, before and after implementation of nucleic acid amplification assays (2014). Clinical, treatment and disease progression data were obtained. RESULTS: A total of 247 children were identified, with an average annual incidence of 24.9/100,000, 57.9% males with a median age of 2 (1-6) years. In the last 5 years, a 1.7-fold increase in the annual incidence, a lower median age at diagnosis and an improved microbiologic yield (49%) was noticed. K. kingae became the most frequent bacteria (51.9%) followed by MSSA (19.2%) and S. pyogenes (9.6%). Children were more often treated for fewer intravenous days (10.7 vs. 13.2 days, P = 0.01) but had more complications (20.6% vs. 11.4%, P = 0.049) with a similar sequelae rate (3.7%). Risk factors for complications were C-reactive protein ≥80 mg/L and Staphylococcus aureus infection, and for sequelae at 6 months, age ≥4 years and CRP ≥ 80 mg/L. CONCLUSIONS: The present study confirms that K. kingae was the most common causative organism of acute SA. There was a trend, although small, for decreasing antibiotic duration. Older children with high inflammatory parameters might be at higher risk of sequelae.

Kingella kingae septic arthritis.

AIMS: The aim of this study was to determine the extent to which patient demographics, clinical presentation, and blood parameters vary in Kingella kingae septic arthritis when compared with those of other organisms, and whether this difference needs to be considered when assessing children in whom a diagnosis of septic arthritis is suspected. METHODS: A prospective case series was undertaken at a single UK paediatric institution between October 2012 and November 2018 of all patients referred with suspected septic arthritis. We recorded the clinical, biochemical, and microbiological findings in all patients. RESULTS: A total of 160 patients underwent arthrotomy for a presumed septic arthritis. Of these, no organism was identified in 61 and only 25 of these were both culture- and polymerase chain reaction (PCR)-negative. A total of 36 patients did not undergo PCR analysis. Of the remaining 99 culture- and PCR-positive patients, K. kingae was the most commonly isolated organism (42%, n = 42). The knee (n = 21), shoulder (n = 9), and hip (n = 5) were the three most commonly affected joints. A total of 28 cases (66%) of K. kingae infection were detected only on PCR. The mean age of K. kingae-positive cases (16.1 months) was significantly lower than that of those whose septic arthitis was due to other organisms (49.4 months; p < 0.001). The mean CRP was significantly lower in the K. kingae group than in the other organism group (p < 0.001). The mean ESR/CRP ratio was significantly higher in K. kingae (2.84) than in other infections (1.55; p < 0.008). The mean ESR and ESR/CRP were not significantly different from those in the 'no organism identified' group. CONCLUSION: K. kingae was the most commonly isolated organism from paediatric culture- and/or PCR-positive confirmed septic arthritis, with only one third of cases detected on routine cultures. It is important to develop and maintain a clinical suspicion for K. kingae infection in young patients presenting atypically. Routine PCR testing is recommended in these patients. Cite this article: Bone Joint J 2021;103-B(3):584-588.

Osteoarticular infection in children.

AIMS: We aimed to describe the epidemiological, biological, and bacteriological characteristics of osteoarticular infections (OAIs) caused by Kingella kingae. METHODS: The medical charts of all children presenting with OAIs to our institution over a 13-year period (January 2007 to December 2019) were reviewed. Among these patients, we extracted those which presented an OAI caused by K. kingae and their epidemiological data, biological results, and bacteriological aetiologies were assessed. RESULTS: K. kingae was the main reported microorganism in our paediatric population, being responsible for 48.7% of OAIs confirmed bacteriologically. K. kingae affects primarily children aged between six months and 48 months. The highest prevalence of OAI caused by K. kingae was between seven months and 24 months old. After the patients were 27 months old, its incidence decreased significantly. The incidence though of infection throughout the year showed no significant differences. Three-quarters of patients with an OAI caused by K. kingae were afebrile at hospital admission, 11% had elevated WBCs, and 61.2% had abnormal CRPs, whereas the ESR was increased in 75%, constituting the most significant predictor of an OAI. On MRI, we noted 53% of arthritis affecting mostly the knee and 31% of osteomyelitis located primarily in the foot. CONCLUSION: K. kingae should be recognized currently as the primary pathogen causing OAI in children younger than 48 months old. Diagnosis of an OAI caused by K. kingae is not always obvious, since this infection may occur with a mild-to-moderate clinical and biological inflammatory response. Extensive use of nucleic acid amplification assays improved the detection of fastidious pathogens and has increased the observed incidence of OAI, especially in children aged between six months and 48 months. We propose the incorporation of polymerase chain reaction assays into modern diagnostic algorithms for OAIs to better identify the bacteriological aetiology of OAIs. Cite this article: Bone Joint J 2021;103-B(3):578-583.

Acute monoarthritis in young children: comparing the characteristics of patients with juvenile idiopathic arthritis versus septic and undifferentiated arthritis.

Acute arthritis is a common cause of consultation in pediatric emergency wards. Arthritis can be caused by juvenile idiopathic arthritis (JIA), septic (SA) or remain undetermined (UA). In young children, SA is mainly caused by Kingella kingae (KK), a hard to grow bacteria leading generally to a mild clinical and biological form of SA. An early accurate diagnosis between KK-SA and early-onset JIA is essential to provide appropriate treatment and follow-up. The aim of this work was to compare clinical and biological characteristics, length of hospital stays, duration of intravenous (IV) antibiotics exposure and use of invasive surgical management of patients under 6 years of age hospitalized for acute monoarthritis with a final diagnosis of JIA, SA or UA. We retrospectively analyzed data from < 6-year-old children, hospitalized at a French tertiary center for acute mono-arthritis, who underwent a joint aspiration. Non-parametric tests were performed to compare children with JIA, SA or UA. Bonferroni correction for multiple comparisons was applied with threshold for significance at 0.025. Among the 196 included patients, 110 (56.1%) had SA, 20 (10.2%) had JIA and 66 (33.7%) had UA. Patients with JIA were older when compared to SA (2.7 years [1.8-3.6] versus 1.4 [1.1-2.1], p < 0.001). Presence of fever was not different between JIA and SA or UA. White blood cells in serum were lower in JIA (11.2 × 109/L [10-13.6]) when compared to SA (13.2 × 109/L [11-16.6]), p = 0.01. In synovial fluid leucocytes were higher in SA 105.5 × 103 cells/mm3 [46-211] compared to JIA and UA (42 × 103 cells/mm3 [6.4-59.2] and 7.29 × 103 cells/mm3 [2.1-72] respectively), p < 0.001. Intravenous antibiotics were administered to 95% of children with JIA, 100% of patients with SA, and 95.4% of UA. Arthrotomy-lavage was performed in 66.7% of patients with JIA, 79.6% of patients with SA, and 71.1% of patients with UA. In children less than 6 years of age with acute mono-arthritis, the clinical and biological parameters currently used do not reliably differentiate between JIA, AS and UA. JIA subgroups that present a diagnostic problem at the onset of monoarthritis before the age of 6 years, are oligoarticular JIA and systemic JIA with hip arthritis. The development of new biomarkers will be required to distinguish JIA and AS caused by Kingella kingae in these patients.

Oropharyngeal Carriage of Kingella kingae and Transient Synovitis of the Hip in Young Children: A Case-control Study.

BACKGROUND: Transient synovitis of the hip affects mostly preschool children, and its etiology is unknown. Kingella kingae has been identified recently as a common etiologic agent of osteoarticular infections (OAI) in young children and could potentially be associated to transient synovitis of the hip. The main objective of this study was to evaluate the association between transient synovitis of the hip and oropharyngeal carriage of K. kingae among preschool children. METHODS: This was a prospective case-control study conducted at a tertiary care pediatric emergency department. Cases were children between 6 and 71 months of ages with a diagnosis of transient synovitis of the hip. For each transient synovitis case, an age-matched control was recruited among children presenting for a trauma. A second control group included children with any OAI. The independent variable was the presence of oropharyngeal K. kingae identified by a specific polymerase chain reaction assay. The primary analysis was the association between oropharyngeal K. kingae carriage and final diagnosis. RESULTS: A total of 73 children were included in the study. Among them, 25 had a transient synovitis, 16 an OAI, and 22 controls. Baseline demographics were similar between the groups. There was no difference in oropharyngeal carriage of K. kingae for children with transient synovitis (5/25; 0.20) in comparison to controls (3/22; 0.14), while it was higher for children with OAI (10/16; 0.63). CONCLUSIONS: There is no association between oropharyngeal K. kingae and transient synovitis of the hip among preschool children.

Kingella negevensis shares multiple putative virulence factors with Kingella kingae.

Kingella negevensis is a newly described gram-negative bacterium in the Neisseriaceae family and is closely related to Kingella kingae, an important cause of pediatric osteoarticular infections and other invasive diseases. Like K. kingae, K. negevensis can be isolated from the oropharynx of young children, although at a much lower rate. Due to the potential for misidentification as K. kingae, the burden of disease due to K. negevensis is currently unknown. Similarly, there is little known about virulence factors present in K. negevensis and how they compare to virulence factors in K. kingae. Using a variety of approaches, we show that K. negevensis produces many of the same putative virulence factors that are present in K. kingae, including a polysaccharide capsule, a secreted exopolysaccharide, a Knh-like trimeric autotransporter, and type IV pili, suggesting that K. negevensis may have significant pathogenic potential.

Neisseria sicca: A Rare Cause of Bacterial Conjunctivitis.

BACKGROUND Neisseria-associated conjunctivitis is a rare cause of bacterial conjunctivitis in adults, with Neisseria gonorrhoeae as the primarily identified infectious strain. Here, we present a rare case of bacterial conjunctivitis due to Neisseria sicca in a 34-year-old immunocompetent man with no prior medical or ocular history. CASE REPORT A 34-year-old man with no significant past medical or ocular history presented with a 3-day history of left periorbital edema, ocular pain, and copious purulent discharge. Bacterial conjunctivitis was suspected due to the rapidity of onset and purulence. Peripheral corneal thinning was identified. Preliminary culture results showed gram-negative diplococci, and the patient was treated for gonococcal infection. Final cultures identified Neisseria sicca, a rarely pathogenic strain of Neisseria species. CONCLUSIONS This is the second reported case of Neisseria sicca-associated conjunctivitis, and the first reported case to have corneal involvement. Neisseria sicca, while typically non-pathogenic, may manifest as conjunctivitis in immunocompetent hosts with a low-risk sexual history.

Agricultural Injury-Associated Chromobacterium violaceum Infection in a Bangladeshi Farmer.

Chromobacterium violaceum is an emerging environmental pathogen that causes life-threatening infection in humans and animals. In October 2017, a Bangladeshi farmer was hospitalized with high-grade fever due to an agricultural injury-related wound infection. Bacteriological and 16S rRNA gene investigation detected C. violaceum in the wound discharge. The patient recovered successfully after a combination treatment with meropenem and ciprofloxacin, followed by prolonged medication to avoid recurrence. We strongly propose to incorporate C. violaceum in the differential diagnosis of wound and skin infections occurring in tropical and subtropical regions, especially when the injury was exposed to soil or sluggish water.

Case Report: A Polymicrobial Vision-Threatening Eye Infection Associated with Polysubstance Abuse.

We report a patient with risk factors for both microbial keratitis and endophthalmitis, which were initially challenging to distinguish. Cultures of corneal scrapings yielded several organisms, including an uncultivable Gram-negative rod, eventually identified as Kingella negevensis. Kingella negevensis is so named because most strains have been isolated in the Negev, a desert region of southern Israel. The epidemiology of K. negevensis remains incompletely understood. We found no other reports in the literature of this organism causing microbial keratitis.

A diagnostic challenge in clinical laboratory: Misidentification of Neisseria subflava as Neisseria meningitidis by MALDI-TOF MS.

MALDI-TOF MS provides fast, easy to perform and cost-effective diagnosis in clinical microbiology laboratories, however in some cases results of MALDI-TOF MS should be confirmed with additional tests. This confirmation is especially important for causes of life-threatening infections like Neisseria meningitidis. In our laboratory, three isolates were identified as N. meningitidis by Bruker MALDI Biotyper (BD, USA) between April 2018 and March 2019 from clinical specimens of blood, sputum, and urine. 16S rRNA sequencing was performed for further investigation. Two of the isolates were identified as Neisseria subflava and only one was confirmed as N. meningitidis by sequencing. These results show that MALDI-TOF MS is not always reliable in the diagnosis of N. meningitidis and clinical microbiologists should confirm these results with additional tests. Also, clinical correlations should be determined. Accurate identification of this microorganism is very important because of the necessity of prophylactic antimicrobial usage and biosafety precautions. Enlarged databases of Neisseria species are needed to overcome this problem.