Osteoarticular infections due to Kingella kingae in children

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.

Systematic Review of Kingella kingae Musculoskeletal Infection in Children: Epidemiology, Impact and Management Strategies

Kingella kingae, a pathogen often responsible for musculoskeletal infections in children is the most common cause of septic arthritis and osteomyelitis in children 6 to 36 months of age. The aim of this study was to perform a systematic review of previous studies to determine the proportion of K. kingae in bacteriologically proven musculoskeletal infections among the pediatric population. A secondary objective was to describe the diagnostic strategies and outcome of patients with musculoskeletal infections caused by K. kingae. A systematic review was conducted to identify publications that report on musculoskeletal infections caused by K. kingae in the pediatric population (patients 0 to <18 years old with microbiologic culture and/or polymerase chain reaction (PCR) confirmation of K. kingae and a description of the musculoskeletal infection involved). Of 144 studies included in this review, we sought to determine the proportion of K. kingae pediatric musculoskeletal infections. A total of 711 (30.8%) out of 2308 pediatric cases with culture and/or PCR proven musculoskeletal infections had K. kingae successfully identified from twenty-nine studies. Of the 1070 patients who were aged less than 48 months, K. kingae was the organism identified in 47.6% of infections. We found the average age from the collated studies to be 17.73 months. Of 520 pediatric musculoskeletal patients in which K. kingae infections were identified and where the studies reported the sites of infection, a large proportion of cases (65%) were joint infections. This was followed by 18.4% osteoarticular infection (concomitant bone and joint involvement), with isolated bone and spine at 11.9% and 3.5%, respectively. Twenty-one papers reported clinical and laboratory findings in children with confirmed K. kingae infection. The median temperature reported at admission was 37.9°C and mean was 38.2°C. Fourteen studies reported on impact and treatment, with the majority of children experiencing good clinical outcome and function following antibiotic treatment with no serious orthopaedic sequelae.

Kingella kingae infections in children

BACKGROUND

Improvements in culture techniques and molecular detection methods have led to findings indicating that, particularly in infants and young children, Kingella kingae is a significantly more important pathogen than previously thought. However, despite this, the pediatric community is still largely unaware of the existence of this organism. The aim of this review is therefore to summarise current knowledge of the epidemiology, transmission, clinical presentation, diagnosis and treatment of K. kingae infections in children.

DISCUSSION

K. kingae is a common coloniser of the oropharynx, can be transmitted from child to child, and can cause outbreaks of infection. Invasive infections almost exclusively occur in children aged between six months and four years of age, and involve mainly joints and bone, less frequently the endocardium, and very rarely other localisations. With the exception of bacteremia and endocarditis, which can be followed by severe complications, the diseases due to K. kingae are usually accompanied by mild to moderate clinical signs and symptoms, and only slightly altered laboratory data. Moreover, they generally respond to widely used antibiotics, although resistant strains are reported. However, the mild symptoms and limited increase in the levels of acute phase reactants create problems because K. kingae disease may be confused with other clinical conditions that have a similar clinical picture.

CONCLUSIONS

Although K. kingae was identified more than 50 years ago, it is poorly known by pediatricians and is not systematically sought in laboratories. Education is therefore necessary in order to reduce the risk of outbreaks, permit the early identification of K. kingae infections, and allow the prompt prescription of adequate therapeutic regimens capable of avoiding the risk of a negative evolution in those cases in which this elusive pathogen can cause significant clinical problems.

Kingella kingae: carriage, transmission, and disease

Kingella kingae is a common etiology of pediatric bacteremia and the leading agent of osteomyelitis and septic arthritis in children aged 6 to 36 months. This Gram-negative bacterium is carried asymptomatically in the oropharynx and disseminates by close interpersonal contact. The colonized epithelium is the source of bloodstream invasion and dissemination to distant sites, and certain clones show significant association with bacteremia, osteoarthritis, or endocarditis. Kingella kingae produces an RTX (repeat-in-toxin) toxin with broad-spectrum cytotoxicity that probably facilitates mucosal colonization and persistence of the organism in the bloodstream and deep body tissues. With the exception of patients with endocardial involvement, children with K. kingae diseases often show only mild symptoms and signs, necessitating clinical acumen. The isolation of K. kingae on routine solid media is suboptimal, and detection of the bacterium is significantly improved by inoculating exudates into blood culture bottles and the use of PCR-based assays. The organism is generally susceptible to antibiotics that are administered to young patients with joint and bone infections. β-Lactamase production is clonal, and the local prevalence of β-lactamase-producing strains is variable. If adequately and promptly treated, invasive K. kingae infections with no endocardial involvement usually run a benign clinical course.

Differentiating Kingella kingae septic arthritis of the hip from transient synovitis in young children

OBJECTIVE

To conduct a retrospective multicenter study to assess the ability of a predictive algorithm to differentiate between children with Kingella kingae infection of the hip and those with transient synovitis.

STUDY DESIGN

Medical charts of 25 Israeli and 9 Spanish children aged 6-27 months with culture-proven K kingae arthritis of the hip were reviewed, and information on the 4 variables included in the commonly used Kocher prediction algorithm (body temperature, refusal to bear weight, leukocytosis, and erythrocyte sedimentation rate) was gathered.

RESULTS

Patients with K kingae arthritis usually presented with mildly abnormal clinical picture and normal serum levels of or near-normal acute-phase reactants. Data on all 4 variables were available for 28 (82%) children, of whom 1 child had none, 6 children had 1, 13 children had 2, 5 had 3, and only 3 children had 4 predictors, implying ≤ 40% probability of infectious arthritis in 20 (71%) children.

CONCLUSIONS

Because of the overlapping features of K kingae arthritis of the hip and transient synovitis in children younger than 3 years of age, Kocher predictive algorithm is not sensitive enough for differentiating between these 2 conditions. To exclude K kingae arthritis, blood cultures and nucleic acid amplification assay should be performed in young children presenting with irritation of the hip, even in the absence of fever, leukocytosis, or a high Kocher score.

Kingella kingae septic arthritis in children: recognising an elusive pathogen

PURPOSE

Kingella kingae is an increasingly identified cause of musculoskeletal infections in young children. We report our experience with a recently developed polymerase chain reaction (PCR) method and review the clinical course of children diagnosed with K. kingae septic arthritis in a tertiary referral paediatric hospital.

METHODS

All positive cases of K. kingae identified by PCR analysis of synovial fluid from August 2010 until July 2013 were included. A chart review was undertaken to determine history, presentation and management.

RESULTS

27 Children (14 male, 13 female) had PCR positive synovial fluid samples for K. kingae with median age of 19 months (range 4 months to 5 years 3 months). The sites of infection were knee (17 cases), hip (2 cases), ankle (5 cases), shoulder (2 cases) and elbow. The median temperature on presentation was 37.1 °C, median peripheral white blood cell count 12.4 (9.9-13.8) × 10(9)/L, erythrocyte sedimentation rate 55 (48-60) mm/h and C-reactive protein 24 (8-47) mg/L. The median synovial fluid white cell count was 21.8 (16.7-45.0) × 10(9)/L. Routine cultures identified K. kingae in only two synovial fluid samples. Two samples were additionally positive for Staphylococcus aureus.

CONCLUSIONS

Kingella kingae is a significant cause of septic arthritis in young children. The authors recommend maintaining a high index of suspicion in young children presenting with joint inflammation, especially if indices of infection are mild. It appears likely that children historically treated with antibiotics for "culture negative" septic arthritis were infected with K. kingae. PCR techniques for detection of K. kingae should be encouraged.

Unusually severe cases of Kingella kingae osteoarticular infections in children

BACKGROUNDS

With the development of molecular biology and specific polymerase chain reaction, Kingella kingae has become the primary diagnosis of osteoarticular infections in young children. Clinical features of these osteoarticular infections are typically mild, and outcome is almost always favorable. We report a series of unusually severe cases of K. kingae osteoarticular infections.

METHODS

All patients with severe osteoarticular infections at presentation were reviewed retrospectively in 2 European pediatric centers. K. kingae was identified using real-time polymerase chain reaction in blood, fluid joint or osseous samples. Clinical, laboratory tests and radiographic data during hospitalization and follow-up were analyzed.

RESULTS

Ten children (mean age 21 ± 12 months) with severe osteoarticular infections caused by K. kingae were identified between 2008 and 2011. Diagnostic delay averaged 13.2 ± 8 days. Only 1 patient was febrile at admission, and 50% children had normal C-reactive protein values (≤10 mg/dL) at presentation. Surgical treatment was performed in all cases. Intravenous antibiotic therapy by cephalosporins for an average of 8 ± 6 days was followed by oral treatment for 27 ± 6 days. Mean follow-up was 24.8 ± 9 months, and satisfactory outcomes were reported in all cases. Two patients (20%) developed a central epiphysiodesis of the proximal humerus during follow-up, but without significant clinical consequence for the moment.

CONCLUSIONS

Because of their mild clinical features at onset, diagnosis of K. kingae osteoarticular infections can be delayed. Care should be taken for early detection and treatment of these infections because bony lytic lesions and potentially definitive growth cartilage damage can occur.

Kingella kingae osteoarticular infections in young children: clinical features and contribution of a new specific real-time PCR assay to the diagnosis

BACKGROUND

Kingella kingae is an emerging pathogen that may be recognized as the most common bacteria responsible for osteoarticular infections (OAI) in young children. However, its diagnosis remains a challenge and thus little evoked in infants, because K. kingae is a difficult germ to isolate on solid medium, and clinical signs are often mild. The main objective of this prospective study is to describe the clinical, biologic, and radiologic features of children with OAI caused by K. kingae. In addition, we describe the usage of a new specific real-time PCR assay in children under 4 years admitted for OAI with a probe that detects 2 independent gene targets from the K. kingae RTX toxin.

PATIENTS AND METHODS

All children less than 4 years admitted in our institution between January 2007 and November 2009 for suspected OAI were enrolled in this prospective study (43 cases). Age, gender, clinical signs, duration of symptoms, bone or joint involved, imaging studies, and laboratory data, including bacterial investigations, full blood count, erythrocyte sedimentation rate, and serum C-reactive protein were collected for analysis.

RESULTS

Identification of the microorganism was possible for 28 cases (65.1%) yielding K. kingae in 23 cases (82.1%). Mean age of children with K. kingae OAI was 19.6 months. Less than 15% of these patients were febrile during the admission, but 46% of them presented a history of fever-peak superior to 38.5 degrees C before admission. Thirty-nine percent of the children with K. kingae OAI had normal C-reactive protein; WBC was elevated in only 2 cases, whereas 21 patients had abnormal erythrocyte sedimentation rate, and 13 abnormal platelet counts. Direct Gram staining and classical isolation methods were negative for all cases subsequently detected as K. kingae OAI by specific real-time PCR.

CONCLUSION

This study confirms that K. kingae is the major bacterial cause of OAI in children less than 4 years. The real-time PCR assay, specific to the K. kingae RTX toxin, provides interesting diagnostic performance when implemented in the routine microbiologic laboratory. Needless to say, a bigger cohort is required to adequately study this new qPCR assay, but the results so far seem promising. The most important additional finding is the mild-to-moderate clinical, radiologic, and biologic inflammatory response to K. kingae infection with the result that these children present few criteria evocative of OAI.

LEVEL OF EVIDENCE

II.

Kingella kingae spondylodiscitis in young children: toward a new approach for bacteriological investigations? A preliminary report

As the result of improved bacteriological techniques, Kingella kingae is a slow-growing Gram-negative coccobacillus that is emerging as an important cause of spondylodiscitis in children younger than 3 years of age. The high pharyngeal carrier rates of this slow-growing Gram-negative coccobacillus combined with the low incidence of identified K. kingae infections is possibly explained by a low virulence of this bacterium. The use of specific real-time polymerase chain reaction (PCR) on blood samples and throat swabs opens new prospects in the bacteriological investigations of young children suspected to have spondylodiscitis, an approach that could prevent, in the future, unnecessary invasive interventions.

Septic arthritis in Western and sub-Saharan African children - a review

This article reviews what is known about the incidence, aetiology, presentation, bacteriology and management of septic arthritis in children. It compares where possible the different presentations and characteristics of this condition in the Western and sub-Saharan African regions.

Outbreak of osteomyelitis/septic arthritis caused by Kingella kingae among child care center attendees

OBJECTIVE

Kingella kingae often colonizes the oropharyngeal and respiratory tracts of children but infrequently causes invasive disease. In mid-October 2003, 2 confirmed and 1 probable case of K kingae osteomyelitis/septic arthritis occurred among children in the same 16- to 24-month-old toddler classroom of a child care center. The objective of this study was to investigate the epidemiology of K kingae colonization and invasive disease among child care attendees.

METHODS

Staff at the center were interviewed, and a site visit was performed. Oropharyngeal cultures were obtained from the staff and children aged 0 to 5 years to assess the prevalence of Kingella colonization. Bacterial isolates were subtyped by pulsed-field gel electrophoresis (PFGE), and DNA sequencing of the 16S rRNA gene was performed. A telephone survey inquiring about potential risk factors and the general health of each child was also conducted. All children and staff in the affected toddler classroom were given rifampin prophylaxis and recultured 10 to 14 days later. For epidemiologic and microbiologic comparison, oropharyngeal cultures were obtained from a cohort of children at a control child care center with similar demographics and were analyzed using the same laboratory methods. The main outcome measures were prevalence and risk factors for colonization and invasive disease and comparison of bacterial isolates by molecular subtyping and DNA sequencing.

RESULTS

The 2 confirmed case patients required hospitalization, surgical debridement, and intravenous antibiotic therapy. The probable case patient was initially misdiagnosed; MRI 16 days later revealed evidence of ankle osteomyelitis. The site visit revealed no obvious outbreak source. Of 122 children in the center, 115 (94%) were cultured. Fifteen (13%) were colonized with K kingae, with the highest prevalence in the affected toddler classroom (9 [45%] of 20 children; all case patients tested negative but had received antibiotics). Six colonized children were distributed among the older classrooms; 2 were siblings of colonized toddlers. No staff (n = 28) or children aged <16 months were colonized. Isolates from the 2 confirmed case patients and from the colonized children had an indistinguishable PFGE pattern. No risk factors for invasive disease or colonization were identified from the telephone survey. Of the 9 colonized toddlers who took rifampin, 3 (33%) remained positive on reculture; an additional toddler, initially negative, was positive on reculture. The children of the control child care center demonstrated a similar degree and distribution of K kingae colonization; of 118 potential subjects, 45 (38%) underwent oropharyngeal culture, and 7 (16%) were colonized with K kingae. The highest prevalence again occurred in the toddler classrooms. All 7 isolates from the control facility had an indistinguishable PFGE pattern; this pattern differed from the PFGE pattern observed from the outbreak center isolates. 16S rRNA gene sequencing demonstrated that the outbreak K kingae strain exhibited >98% homology to the ATCC-type strain, although several sequence deviations were present. Sequencing of the control center strain demonstrated more homology to the outbreak center strain than to the ATCC-type strain.

CONCLUSIONS

This is the first reported outbreak of invasive K kingae disease. The high prevalence in the affected toddler class and the matching PFGE pattern are consistent with child-to-child transmission within the child care center. Rifampin was modestly effective in eliminating carriage. DNA sequence analysis suggests that there may be considerable variability within the species K kingae and that different K kingae strains may demonstrate varying degrees of pathogenicity.

Kingella kingae: from medical rarity to an emerging paediatric pathogen

In recent years, Kingella kingae has emerged as an important cause of invasive infections in young children, especially septic arthritis, osteomyelitis, spondylodiscitis, bacteraemia, and endocarditis, and less frequently lower respiratory tract infections and meningitis. The organism is part of the pharyngeal flora of young children and is transmitted from child-to-child. The clinical presentation of invasive K kingae disease is often subtle and laboratory tests are frequently normal. A substantial fraction of children with invasive K kingae infections have a recent history of stomatitis or symptoms of upper-respiratory-tract infection. The organism is susceptible to a wide array of antibiotics that are usually given empirically to young children including beta lactams, and with the exception of cases of endocarditis, the disease runs a benign clinical course. Although isolation and recognition of the organism is not difficult, clinicians and microbiologists should be aware of its fastidious nature. To optimise the recovery of K kingae, inoculation of synovial fluid specimens into blood culture vials is strongly recommended.

Epidemiological features of invasive Kingella kingae infections and respiratory carriage of the organism

The age, sex, and seasonal distributions of invasive Kingella kingae infections in southern Israel were examined and compared to the epidemiology of respiratory carriage of the organism. Medical records of all patients diagnosed between 1988 and 2002 were reviewed, and 2,044 oropharyngeal specimens were cultured on selective media during two periods (February to May and October to December) in 2001. Invasive infections significantly affected children (73 of 74 patients [98.6%] were younger than 4 years), 50 patients (67.8%) were males (P = 0.045), and 55 episodes (74.3%) occurred between July and December (P = 0.004). Carriage was higher in the 0- to 3-year-old group and decreased with increasing age (P for trend = 0.0008). Carriage rates were similar in both sexes and did not significantly differ between the February-to-May and October-to-December periods. The highest rate of carriage of K. kingae coincided with the age (less than 4 years) at which invasive infections were especially frequent. The peculiar sex and seasonal distributions of invasive disease, however, cannot be readily explained by the epidemiology of respiratory carriage. Viral infections and other yet-to-be-defined cofactors may play a role in the causation of invasive K. kingae infections.

Soft tissue infection caused by Kingella kingae in a child

During the last years an increasing number of reports concerning Kingella kingae infections in children has been published. Most cases were osteoarticular infections. The authors report the clinical and laboratory findings from a 3-year-old child with a presternal soft tissue infection due to K kingae. After surgical excochleation and antibiotic treatment there was an uneventful recovery. J Pediatr Surg 36:946-947.

Kingella kingae infections in children

OBJECTIVE

To increase awareness of Kingella kingae infections in children by presenting four cases seen at the Gold Coast Hospital, Southport, Queensland, and reviewing the literature.

METHODOLOGY

Records of the four cases were reviewed and relevant information described. A MEDLINE search of the English literature from 1983 to 1998 was conducted.

RESULTS

Osteoarticular infections are the commonest type of invasive paediatric infection but bacteraemia and endocarditis also occur. Isolation of the organism is difficult but inoculation of the specimen into enriched blood culture systems improves the recovery rate. The majority of isolates are sensitive to beta-lactam antibiotics but resistance has been described.

CONCLUSIONS

Kingella kingae infections in children are more common than previously recognized. The organism should be actively sought in any child with suspected osteoarticular infections. Recommended empiric therapy is a third generation cephalosporin until susceptibility to penicillin is confirmed.