Isolation of Kingella kingae from synovial fluids using four commercial blood culture bottles

Exploring the Utility of Multiplex Infectious Disease Panel Testing for Diagnosis of Infection in Different Body Sites: A Joint Report of the Association for Molecular Pathology, American Society for Microbiology, Infectious Diseases Society of America, and Pan American Society for Clinical Virology

The use of clinical molecular diagnostic methods for detecting microbial pathogens continues to expand and, in some cases, supplant conventional identification methods in various scenarios. Analytical and clinical benefits of multiplex molecular panels for the detection of respiratory pathogens have been demonstrated in various studies. The use of these panels in managing different patient populations has been incorporated into clinical guidance documents. The Association for Molecular Pathology's Infectious Diseases Multiplex Working Group conducted a review of the current benefits and challenges to using multiplex PCR for the detection of pathogens from gastrointestinal tract, central nervous system, lower respiratory tract, and joint specimens. The Working Group also discusses future directions and novel approaches to detection of pathogens in alternate specimen types, and outlines challenges associated with implementation of these multiplex PCR panels.

The Past, Present, and Future of Kingella kingae Detection in Pediatric Osteoarthritis

As a result of the increasing use of improved detection methods, Kingella kingae, a Gram-negative component of the pediatric oropharyngeal microbiota, is increasingly appreciated as the prime etiology of septic arthritis, osteomyelitis, and spondylodiscitis in children aged 6 to 48 months. The medical literature was reviewed to summarize the laboratory methods required for detecting the organism. Kingella kingae is notoriously fastidious, and seeding skeletal system samples onto solid culture media usually fails to isolate it. Inoculation of synovial fluid aspirates and bone exudates into blood culture vials enhances Kingella kingae recovery by diluting detrimental factors in the specimen. The detection of the species has been further improved by nucleic acid amplification tests, especially by using species-specific primers targeting Kingella kingae's rtxA, groEL, and mdh genes in a real-time PCR platform. Although novel metagenomic next-generation technology performed in the patient's plasma sample (liquid biopsy) has not yet reached its full potential, improvements in the sensitivity and specificity of the method will probably make this approach the primary means of diagnosing Kingella kingae infections in the future.

Novel strategies to diagnose prosthetic or native bone and joint infections

INTRODUCTION

Bone and Joint Infections (BJI) are medically important, costly and occur in native and prosthetic joints. Arthroplasties will increase significantly in absolute numbers over time as well as the incidence of Prosthetic Joint Infections (PJI). Diagnosis of BJI and PJI is sub-optimal. The available diagnostic tests have variable effectiveness, are often below standard in sensitivity and/or specificity, and carry significant contamination risks during the collection of clinical samples. Improvement of diagnostics is urgently needed.

AREAS COVERED

We provide a narrative review on current and future diagnostic microbiology technologies. Pathogen identification, antibiotic resistance detection, and assessment of the epidemiology of infections via bacterial typing are considered useful for improved patient management. We confirm the continuing importance of culture methods and successful introduction of molecular, mass spectrometry-mediated and next-generation genome sequencing technologies. The diagnostic algorithms for BJI must be better defined, especially in the context of diversity of both disease phenotypes and clinical specimens rendered available.

EXPERT OPINION

Whether interventions in BJI or PJI are surgical or chemo-therapeutic (antibiotics and bacteriophages included), prior sensitive and specific pathogen detection remains a therapy-substantiating necessity. Innovative tests for earlier and more sensitive and specific detection of bacterial pathogens in BJI are urgently needed.

Aspergillus terreus Spondylodiscitis in an Immunocompromised Child

We report the case of a 12-year-old immunocompromised boy with spondylodiscitis of the thoracolumbar spine caused by Aspergillus terreus. Microbiologic diagnosis was confirmed by inoculation of aspiration fluid into blood culture bottles. Because of noncompliance, the patient was treated with extended voriconazole therapy (23 months) with regular serum drug concentration monitoring and intermittent direct observation therapy in an outpatient clinic. The Aspergillus genus contains species that are important causes of morbidity and mortality in immunocompromised hosts. Although the lung is the main target of invasive Aspergillosis, more severe forms such as Aspergillus osteomyelitis can occur. A. fumigatus is the most common cause of Aspergillus osteomyelitis, causing 55%-61% of all cases, whereas A. terreus causes 2.3%-2.8% of cases. The vertebral bodies are the most commonly affected sites, occurring in 46%-49% of cases., Here, we report the case of an immunocompromised 12-year-old boy with thoracolumbar spondylodiscitis caused by A. terreus.

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.

Evaluation of a real-time PCR assay for simultaneous detection of Kingella kingae and Staphylococcus aureus from synovial fluid in suspected septic arthritis

Direct plating of synovial fluid (SF) on agar-based media often fails to identify pathogens in septic arthritis (SA). We developed a PCR assay for the simultaneous detection of Kingella kingae and Staphylococcus aureus from SF to evaluate molecular detection in SF and to estimate the incidence of K. kingae in SA in North America. The assay was based on detection of the cpn60 gene of K. kingae and the spa gene of S. aureus in multiplex real-time PCR. K. kingae was identified in 50% of patients between 0 and 5 yr of age (n=6) but not in any patients >18 yr old (n=105). Direct plating of SF on agar-based media failed to detect K. kingae in all samples. The PCR assay was inferior to the culture-based method for S. aureus, detecting only 50% of culture-positive cases. Our findings suggest that K. kingae is a common pathogen in pediatric SA in North America, in agreement with previous reports from Europe. PCR-based assays for the detection of K. kingae may be considered in children with SA, especially in those with a high degree of clinical suspicion.

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.

30 years of study of Kingella kingae: post tenebras, lux

Kingella kingae is a Gram-negative bacterium that is today recognized as the major cause of joint and bone infections in young children. This microorganism is a member of the normal flora of the oropharynx, and the carriage rate among children under 4 years of age is approximately 10%. K. kingae is transmitted from child to child through close personal contact. Key virulence factors of K. kingae include expression of type IV pili, Knh-mediated adhesive activity and production of a potent RTX toxin. The clinical presentation of K. kingae invasive infection is often subtle and may be associated to mild-to-moderate biologic inflammatory responses, highlighting the importance a high index of suspicion. Molecular diagnosis of K. kingae infections by nucleic acid amplification techniques enables identification of this fastidious microorganism. Invasive infections typically respond favorably to medical treatment, with the exception of cases of endocarditis, which may require urgent valve replacement.

Detection of Kingella kingae osteoarticular infections in children by oropharyngeal swab PCR

OBJECTIVE

The purpose of this study was to investigate if oropharyngeal swab polymerase chain reaction (PCR) could predict osteoarticular infection (OAI) due to Kingella kingae in young children.

METHODS

One hundred twenty-three consecutive children aged 6 to 48 months presenting with atraumatic osteoarticular complaints were prospectively studied. All had a clinical evaluation, imaging, and blood samples. Blood and oropharyngeal specimens were tested with a PCR assay specific for K kingae. OAI was defined as bone, joint, or blood detection of pathogenic bacteria, or MRI consistent with infection in the absence of positive microbiology. K kingae OAI was defined by blood, bone, or synovial fluid positivity for the organism by culture or PCR.

RESULTS

Forty children met the OAI case definition; 30 had K kingae OAI, 1 had another organism, and 9 had no microbiologic diagnosis. All 30 oropharyngeal swabs from the K kingae case patients and 8 swabs from the 84 patients without OAI or with OAI caused by another organism were positive. The sensitivity and specificity of the oropharyngeal swab PCR assay for K kingae were 100% and 90.5%, respectively.

CONCLUSIONS

Detection of K kingae DNA in oropharyngeal swabs of children with clinical findings of OAI is predictive of K kingae OAI. If these findings are replicated in other settings, detection of K kingae by oropharyngeal swab PCR could improve the recognition of OAI.

Antibiotic treatment for acute haematogenous osteomyelitis of childhood: moving towards shorter courses and oral administration

Acute haematogenous osteomyelitis (AHOM) of childhood usually affects the long bones of the lower limbs. Although almost any agent may cause AHOM, Staphylococcus aureus is the most common bacterium, followed by Streptococcus pneumoniae and, in some countries, Salmonella spp. and Kingella kingae. Magnetic resonance imaging (MRI) has improved the diagnostic accuracy of traditional radiography and scintigraphy. Except for the pre-treatment diagnostic sample from bone before the institution of antibiotic therapy, no other surgery is usually required. Traditionally, non-neonatal AHOM has been treated with a 1-3-month course of antibiotics, including an intravenous (i.v.) phase for the first weeks, but recent prospective randomised studies challenge this approach. For most uncomplicated cases, a course of 20 days including an i.v. period of 2-4 days suffices, provided large enough doses of a well-absorbed agent (clindamycin or a first-generation cephalosporin, local resistance permitting) are used, administration is four times daily and most symptoms and signs subside within a few days. Serum C-reactive protein (CRP) is a good guide in monitoring the course of illness, and the antimicrobial can usually be discontinued if CRP has decreased to <20 mg/L. Newer and costly agents, such as linezolid, should be reserved for cases due to resistant S. aureus strains. AHOM in neonates and immunocompromised patients probably requires a different approach. Because sequelae may develop slowly, follow-up for at least 1 year post hospitalisation is recommended.

Molecular diagnosis of Kingella kingae osteoarticular infections by specific real-time PCR assay

Kingella kingae is an emerging pathogen that is recognized as a causative agent of septic arthritis and osteomyelitis, primarily in infants and children. The bacterium is best detected by rapid inoculation in blood culture systems or by real-time PCR assays. Pathogenesis of the agent was linked recently to the production of a potent cytotoxin, known as RTX, which is toxic to a variety of human cell types. The locus encoding the RTX toxin is thought to be a putative virulence factor, and is, apparently, essential for inducing cytotoxic effects on respiratory epithelial, synovial and macrophage-like cells. Herein, we describe a novel real-time PCR assay that targets the RTX toxin gene and illustrate its use in two clinical cases. The assay exhibited a sensitivity of 30 c.f.u., which is 10-fold more sensitive than a previously published semi-nested broad-range 16S rRNA gene PCR, and showed no cross-reactivity with several related species and common osteoarticular pathogens.

Update on the management of skin, soft-tissue, and osteoarticular infections in children

PURPOSE OF REVIEW

To provide an update on the diagnosis and management of skin, soft-tissue, and osteoarticular infections in children.

RECENT FINDINGS

Our understanding of the epidemiology of skin and soft-tissue infections and osteoarticular infections is changing rapidly. Community-associated methicillin-resistant Staphylococcus aureus has become a predominant cause of childhood skin and soft-tissue infections. Kingella kingae is also increasingly identified as a cause of osteoarticular infections. Challenges in Staphylococcus aureus treatment and Kingella kingae identification are changing the approach to skin and soft-tissue infections and osteoarticular infections.

SUMMARY

Community-associated methicillin-resistant Staphylococcus aureus should be considered a cause of skin and soft-tissue infections. Empiric antimicrobial choices should be modified in areas in which there is a more than 10% prevalence of community-associated methicillin-resistant Staphylococcus aureus infection. Decontamination of shared sports equipment should be undertaken to minimize person-to-person spread. No established guideline for eradication of carriage of community-associated methicillin-resistant Staphylococcus aureus exists. Kingella kingae is a more prevalent cause of osteoarticular infections than previously recognized and can cause outbreaks of invasive infection via person-to-person transmission. Modification of culturing procedures for osteoarticular infections including inoculation of infected joint fluid and bone in blood-culture bottles should be considered.

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.

Enhanced culture detection of Kingella kingae, a pathogen of increasing clinical importance in pediatrics

Osteoarticular infection and occult bacteremia are the 2 invasive infectious pathologies most frequently associated in childhood with Kingella kingae. We report a series of 11 patients in whom osteomyelitis predominates over septic arthritis, which is the reverse of other series, probably as a consequence of inoculation of samples during surgery on agar media, used in combination with or as an alternative to inoculation into blood culture bottles. Although K. kingae infections usually follow a benign clinical course, we noted 2 patients with mild orthopedic sequelae.

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.