Cause Of Osteoarticular Infections Research Articles

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.

Kingella kingae PilC1 and PilC2 are adhesive multifunctional proteins that promote bacterial adherence, twitching motility, DNA transformation, and pilus biogenesis.

The gram-negative bacterium Kingella kingae is a leading cause of osteoarticular infections in young children and initiates infection by colonizing the oropharynx. Adherence to respiratory epithelial cells represents an initial step in the process of K. kingae colonization and is mediated in part by type IV pili. In previous work, we observed that elimination of the K. kingae PilC1 and PilC2 pilus-associated proteins resulted in non-piliated organisms that were non-adherent, suggesting that PilC1 and PilC2 have a role in pilus biogenesis. To further define the functions of PilC1 and PilC2, in this study we eliminated the PilT retraction ATPase in the ΔpilC1ΔpilC2 mutant, thereby blocking pilus retraction and restoring piliation. The resulting strain was non-adherent in assays with cultured epithelial cells, supporting the possibility that PilC1 and PilC2 have adhesive activity. Consistent with this conclusion, purified PilC1 and PilC2 were capable of saturable binding to epithelial cells. Additional analysis revealed that PilC1 but not PilC2 also mediated adherence to selected extracellular matrix proteins, underscoring the differential binding specificity of these adhesins. Examination of deletion constructs and purified PilC1 and PilC2 fragments localized adhesive activity to the N-terminal region of both PilC1 and PilC2. The deletion constructs also localized the twitching motility property to the N-terminal region of these proteins. In contrast, the deletion constructs established that the pilus biogenesis function of PilC1 and PilC2 resides in the C-terminal region of these proteins. Taken together, these results provide definitive evidence that PilC1 and PilC2 are adhesins and localize adhesive activity and twitching motility to the N-terminal domain and biogenesis to the C-terminal domain.

Kingella kingae and Viral Infections.

Kingella kingae (K. kingae) is an oropharyngeal commensal agent of toddlers and the primary cause of osteoarticular infections in 6–23-month-old children. Knowing that the oropharynx of young children is the reservoir and the portal of entry of K. kingae, these results suggested that a viral infection may promote K. kingae infection. In this narrative review, we report the current knowledge of the concomitance between K. kingae and viral infections. This hypothesis was first suggested because some authors described that symptoms of viral infections were frequently concomitant with K. kingae infection. Second, specific viral syndromes, such as hand, foot and mouth disease or stomatitis, have been described in children experiencing a K. kingae infection. Moreover, some clusters of K. kingae infection occurring in daycare centers were preceded by viral outbreaks. Third, the major viruses identified in patients during K. kingae infection were human rhinovirus or coxsackievirus, which both belong to the Picornaviridae family and are known to facilitate bacterial infections. Finally, a temporal association was observed between human rhinovirus circulation and K. kingae infection. Although highly probable, the role of viral infection in the K. kingae pathophysiology remains unclear and is based on case description or temporal association. Molecular studies are needed.

Osteoarticular infections in infants under 3 months of age.

Acute osteoarticular infections (OAI) in infants under 3 months of age (≤3M) are rare and remain a diagnostic challenge. Orthopedic complications and functional sequelae have been less well described in this age group. Our aims were to evaluate trends in aetiology, management, and outcomes of OAI ≤ 3M, and to compare these younger children who have OAI with older children. A longitudinal observational study was conducted of OAI cases admitted to tertiary care pediatric hospital from 2008 to 2018. OAI ≤ 3M was compared with children above 3 months. Clinical, microbiological, imaging, and outcome data were analyzed. We identified 24 (9.1%) of the 263 OAI in children under 3 months. Analyzing OAI ≤ 3M there was a twofold increase since 2014; 54% were males with a median age of 28 days (IQR: 13.5-60.0), 10 (41.7%) were premature and nine (37.5%) had healthcare-associated infections. Microbiological causes were identified in 87.5%, mostly Staphylococcus aureus (57.1%) and Group B Streptococcus (23.8%), and 25% were multidrug-resistant (5 methicillin-resistant S. aureus and 1 Enterobacter cloacae). Bacteremia (100% vs 36.8%, P = 0.037), multidrug resistant bacteria (75% vs 16, P = 0.04), and healthcare-associated infections (100% vs 26.3%, P = 0.014) were associated with sequelae. Comparing OAI ≤ 3M with older children, OAI ≤ 3M were treated with longer antibiotic courses, had more complications and sequelae (17.4% vs 3.2%, P = 0.002). S. aureus is still the most common cause of OAI ≤ 3M, and 25% of causative bacteria were multidrug-resistant bacteria. Complications and sequelae were more frequent in OAI ≤ 3M when compared with older children.

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.

242. Rising Incidence of Finegoldia magna among Prosthetic Joint Infections

Background Finegoldia magna is an anaerobic, Gram-positive coccus infrequently associated with osteoarticular infections. Since the adoption of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF), F. magna has been increasingly reported as a cause of osteoarticular infections. Our objective was to determine the incidence of F. magna prosthetic joint infections (PJIs) within our institution. MethodsWe conducted a retrospective longitudinal survey from 1 January 2016 - 31 December 2020 at an academic tertiary care referral center. We constructed two Poisson count models to assess the incidence of Finegoldia magna PJIs: one consisting of a clinical microbiology database of synovial fluid and surgical tissue cultures and one using a PJI registry. Time served as the covariate of interest. We used number of cultures as an offset term in the clinical microbiology model, and number of PJI cases as the offset term in the prosthetic joint registry model –reflecting the relevant denominator for each dataset. The microbiology database was limited to synovial fluid aspirates and surgical tissue cultures to minimize risk of confounding by contaminants. ResultsThe PJI registry included 44 F. magna infections occurring among 4,706 (0.9%) PJIs. The microbiology survey included 99 F. magna isolates from 43,940 (0.2%) cultures sent from joint aspirates or surgical tissue cultures. Among overall synovial and surgical tissue cultures, we found no significant increase in F. magna over time (incidence rate ratio [IRR] 1.0, 95% CI: 0.9-1.2, Figure 1A). Within the PJI registry, however, we observed a 40% per-year increase in F. magna incidence (IRR 1.4, 95% CI: 1.1-1.8, Figure 1B). Figure 1 Incidence of Finegoldia magna Over TimeConclusionAdoption of MALDI-TOF has expanded the clinical microbiology laboratory’s capacity for rapid speciation, sometimes revealing previously unseen epidemiologic trends. While we saw no significant change in overall incidence of F. magna among synovial and surgical tissue cultures, we did detect a significant increase specifically among PJI cases. F. magna warrants attention as an emerging pathogen among PJI. Disclosures All Authors: No reported disclosures

Infección neumocócica osteoarticular en niños atendidos en un hospital pediátrico de referencia de Misiones, Argentina. Trece años de vigilancia

Streptococcus pneumoniae is a rare cause of osteoarticular infections. We describe 5documented cases that occurred in 2005, 2009, 2011, 2015 and 2017 in patients admitted to the Pediatric Provincial Reference Hospital of Misiones. These cases corresponded to a 4-year-old boy and 4 girls aged 11, 10, 6 years and 4 months with a diagnosis of osteomyelitis of the scapula and humerus, arthritis of the hip, ankle and osteomyelitis of the distal fibula. All of them were in good general condition on admission and one of them was seropositive for human immunodeficiency virus. All the recovered isolates were susceptible to β-lactams and only one isolate showed joint resistance to macrolides and tetracycline. Three isolates were serotyped, 2of which carried vaccine serotypes (19F and 7F). Despite its low frequency, the etiology of S.pneumoniae should be considered among the osteoarticular infections. Our findings enhance the role of the Bacteriology laboratory in the diagnosis by microbiological culture and contribute to documenting the epidemiological behavior of this pathogen.

Asymptomatic Pharyngeal Carriage of Kingella kingae Among Young Children in Vancouver, British Columbia, Canada.

Kingella kingae has emerged as a significant cause of osteoarticular infections in young children. Pharyngeal colonization is considered a prerequisite for invasive K. kingae infection. We conducted a prospective study to estimate the prevalence of pharyngeal carriage of K. kingae among healthy young children in Vancouver. From March 2016 to May 2017, children between 6 and 48 months of age visiting British Columbia Children's Hospital outpatient clinics for noninfectious causes were included in the study. Another set of participants was enrolled from a day-care center located at British Columbia Children's Hospital. A single-throat swab was collected after obtaining consent from parent/guardian. The samples were stored at -70°C and tested using an in-house developed real-time polymerase chain reaction assay. Epidemiologic characteristics and risk factors for K. kingae colonization were collected via a study questionnaire. A total of 179 children were enrolled in the study, but only 174 samples were eligible for testing. Of the 174 samples, 5 had indeterminate results and the remaining 169 samples were negative by K. kingae polymerase chain reaction. The median age of participants was 23 months. About 36% of children were attending day care and had another sibling <5 years of age. Previous history of cold symptoms and antibiotic use was reported in 42% and 12%, respectively. The results of our study showed no prevalence of asymptomatic pharyngeal carriage of K. kingae in young children in Vancouver. Additional multicenter studies may help to understand the differences in pharyngeal carriage rate among healthy children.

Pediatric Methicillin-Resistant Staphylococcus aureus Osteoarticular Infections.

Osteoarticular infections (OSI) are a significant cause of hospitalizations and morbidity in young children. The pediatric patient with OSI presents unique challenges in diagnosis and management due to higher morbidity, effect on growth plate with associated long-lasting sequelae, and challenges in early identification and management. Methicillin-resistant Staphylococcus aureus (MRSA), first described in the 1960s, has evolved rapidly to emerge as a predominant cause of OSI in children, and therefore empiric treatment for OSI should include an antibiotic effective against MRSA. Characterizing MRSA strains can be done by antimicrobial susceptibility testing, detection of Panton–Valentine leukocidin (PVL) gene, staphylococcal cassette chromosome mec (SCCmec) typing, pulsed-field gel electrophoresis (PFGE), and multilocus sequence typing (MLST). Worldwide, community-onset methicillin-resistant staphylococcal disease is widespread and is mainly associated with a PVL-producing clone, ST8/USA300. Many studies have implied a correlation between PVL genes and more severe infection. We review MRSA OSI along with the pertinent aspects of its pathogenesis, clinical spectrum, diagnosis, and current guidelines for management.

Real-Time PCR Assay for Detection of Kingella kingae in Children

Background Kingella kingae is a known cause of osteoarticular infections in children younger than 4 years of age, but it is not always recoverable in culture. Molecular methods are increasingly used for diagnosis. Methods To facilitate diagnosis of K. kingae septic arthritis, we developed a real-time polymerase chain reaction (PCR) assay for the detection of K. kingae that targets the repeat-in-toxin gene (rtxB). Results We present three pediatric patients with K. kingae septic arthritis at our institution who were diagnosed using the real-time PCR assay. All underwent arthrotomy with irrigation and debridement and were symptom-free after 3 weeks of therapy with β-lactam antibiotics. Cultures of synovial fluid or tissue grew K. kingae in two of three; K. kingae real-time PCR was positive in all three patients. In addition, 11 cases of K. kingae osteoarticular infection were diagnosed through Mayo Medical Laboratories using this assay. The limit of detection of the real-time PCR assay was 73.7 colony-forming unit (CFU)/µL for tissue and 1.3 CFU/µL for synovial fluid. Conclusions PCR-based detection methods are faster and more sensitive than conventional culture-based methods for the diagnosis of K. kingae osteoarticular infections in children.

Recognition of Kingella kingae as a major cause of osteoarticular infections in young children

Recognition of Kingella kingae as a major cause of osteoarticular infections in young children

Kingella kingae Expresses Four Structurally Distinct Polysaccharide Capsules That Differ in Their Correlation with Invasive Disease.

Kingella kingae is an encapsulated gram-negative organism that is a common cause of osteoarticular infections in young children. In earlier work, we identified a glycosyltransferase gene called csaA that is necessary for synthesis of the [3)-β-GalpNAc-(1→5)-β-Kdop-(2→] polysaccharide capsule (type a) in K. kingae strain 269–492. In the current study, we analyzed a large collection of invasive and carrier isolates from Israel and found that csaA was present in only 47% of the isolates. Further examination of this collection using primers based on the sequence that flanks csaA revealed three additional gene clusters (designated the csb, csc, and csd loci), all encoding predicted glycosyltransferases. The csb locus contains the csbA, csbB, and csbC genes and is associated with a capsule that is a polymer of [6)-α-GlcpNAc-(1→5)-β-(8-OAc)Kdop-(2→] (type b). The csc locus contains the cscA, cscB, and cscC genes and is associated with a capsule that is a polymer of [3)-β-Ribf-(1→2)-β-Ribf-(1→2)-β-Ribf-(1→4)-β-Kdop-(2→] (type c). The csd locus contains the csdA, csdB, and csdC genes and is associated with a capsule that is a polymer of [P-(O→3)[β-Galp-(1→4)]-β-GlcpNAc-(1→3)-α-GlcpNAc-1-] (type d). Introduction of the csa, csb, csc, and csd loci into strain KK01Δcsa, a strain 269–492 derivative that lacks the native csaA gene, was sufficient to produce the type a capsule, type b capsule, type c capsule, and type d capsule, respectively, indicating that these loci are solely responsible for determining capsule type in K. kingae. Further analysis demonstrated that 96% of the invasive isolates express either the type a or type b capsule and that a disproportionate percentage of carrier isolates express the type c or type d capsule. These results establish that there are at least four structurally distinct K. kingae capsule types and suggest that capsule type plays an important role in promoting K. kingae invasive disease.

Extensive Osteomyelitis and Septic Arthritis Caused by Bacteroides Fragilis in a Child with Sickle Cell Disease: A Case Report

Patients with sickle cell disease (SCD) have a higher risk of developing osteoarticular (OA) infections, which are most commonly caused by <i>Salmonella</i> and <i>Staphylococcus aureus</i>. Here, we report an unusual case of severe anaerobic osteoarticular infection caused by <i>Bacteroides fragilis</i> in an 11-year-old girl with SCD. Her management was challenging because she required joint aspiration twice, two rounds of surgical debridement, and a prolonged course of combined antimicrobial therapy to achieve clinical and biochemical improvement. To achieve good clinical outcomes, an anaerobic cause of OA infections should be considered in patients with SCD if improvement does not occur using the usual empirical antibiotic regimens.

Kingella kingae infections can cluster among young children in close contact

Over the last few decades Kingella kingae has ascended in the family of pathogenic bacteria from a rare cause of endocarditis to a relatively common cause of osteoarticular infections in children younger than 4 years of age. Fastidious nature of growth in culture likely hampered establishing the organism's rightful place among infectious diseases in children. Molecular diagnostic techniques now available will permit a better assessment of the role(s) of K kingae in an expected wider spectrum of infections and across continents. To date, much of what is known of the clinical epidemiology of disease and colonization patterns in young children are from studies in Israel. In this issue of The Journal, Yagupsky et al add another Kingella insight from studying daycares in relatively close communities in Israel in which contact is intense. They found clustering of disease, in association with clonal spread of presumably more pathogenic strains, and high oropharyngeal transmissibility among colleagues under 24 months of age. Article page 135▶ Outbreaks of Invasive Kingella kingae Infections in Closed CommunitiesThe Journal of PediatricsVol. 169PreviewTo describe the results of the epidemiologic investigation of outbreaks of invasive Kingella kingae infections among attendees at daycare facilities located in 4 closed communities in Israel. Full-Text PDF

Pediatric osteoarticular infections caused by Streptococcus pneumoniae before and after the introduction of the heptavalent pneumococcal conjugate vaccine

Streptococcus pneumoniae is an uncommon cause of osteoarticular infections (OAI) in children. The objective of this study was to investigate the clinical and laboratory characteristics of pneumococcal OAI before and after the introduction of the heptavalent pneumococcal conjugate vaccine (PCV7). Data were retrospectively collected from children aged <16 years who were hospitalized for pneumococcal OAI between 1997 and 2007 in four Parisian teaching hospitals. Forty-three children were included (32 with arthritis and 11 with osteomyelitis) and the median age of these children was 12.5 months (range 3 months to 14 years). Serotypes were available for 19/43 strains (44 %) from 1997 onwards and for 12/13 strains (92 %) from 2005 onwards. Seven unvaccinated children were infected with vaccine serotypes and we observed only one vaccine failure. After the introduction of PCV7, we noted an increase in short-term complications and the emergence of serotype 19A, which was penicillin-intermediate in 86 % of cases. After PCV7 introduction, serotype 19A was the most frequent serotype implicated in pediatric pneumococcal OAI. The 13-valent pneumococcal conjugate vaccine introduced in France in June 2010 should cover the emerging serotype.

Kingella Kingae Osteoarticular Infections in Young Children: Clinical Features and Contribution of a New Specific Real-time PCR Assay to the Diagnosis

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. 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. 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. 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. II.

Specific Real-Time Polymerase Chain Reaction Places Kingella kingae as the Most Common Cause of Osteoarticular Infections in Young Children

The use of universal 16S rDNA polymerase chain reaction (PCR) has recently shown that the place of Kingella kingae in osteoarticular infections (OAI) in young children has been underestimated, but this technique is not the most sensitive or the most rapid method for molecular diagnosis. We developed a specific real-time PCR method to detect K. kingae DNA and applied it to the etiologic diagnosis of OAI. All children admitted to a pediatric unit for OAI between January 2004 and December 2005 were enrolled in this prospective study. Culture-negative osteoarticular specimens were tested by 16S rDNA PCR and by K. kingae-specific real-time PCR when sufficient sample remained. By culture alone, a pathogen was identified in 45% of the 131 specimens tested (Staphylococcus aureus, n = 25; K. kingae, n = 17; others, n = 18). 16S rDNA PCR and K. kingae-specific PCR were both applied to 61 of the culture-negative samples. The combination of culture and 16S rDNA PCR identified a pathogen in 61% of cases (K. kingae DNA, n = 16; DNA of other microorganisms, n = 5). Specific real-time PCR identified a further 6 cases caused by K. kingae and confirmed all 16 universal PCR-positive cases, bringing the overall documentation rate to 66%. K. kingae was the leading cause of OAI in this pediatric series (n = 39, 45%), followed by S. aureus (n = 25, 29%) The K. kingae-specific real-time PCR places K. kingae as the leading cause of OAI in children at our hospital.

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

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

Contribution of a Broad Range Polymerase Chain Reaction to the Diagnosis of Osteoarticular Infections Caused by Kingella kingae

Microbiologic diagnosis of septic arthritis and osteomyelitis in children is hindered by the less than optimal yield of blood and osteoarticular fluid cultures. All patients admitted to a pediatric unit for osteoarticular infections (OAI) between January 2001 and February 2004 were enrolled in this prospective study. Osteoarticular fluid and biopsy samples that were negative by conventional culture were tested by polymerase chain reaction (PCR) with universal 16S ribosomal DNA primers. We enrolled 171 children. Culture was positive in 64 cases (37.4%), yielding Kingella kingae in 9 cases. The 107 culture-negative specimens were tested by 16S ribosomal DNA PCR. Fifteen samples (14%) were positive, all for Kingella DNA sequences. K. kingae was the second cause of OAI in this population (30.4%), after Staphylococcus aureus (38%). Patients with Kingella infection diagnosed by culture (9 cases) did not differ from those diagnosed by PCR (15 cases) in terms of their clinical characteristics (including prior antibiotic therapy). The characteristics of the 24 children with arthritis (n = 17) or osteomyelitis (n = 7) were similar to those reported elsewhere. Fever (>38 degrees C) and symptom onset shortly before hospitalization (median, 4.5 days) were significantly associated with arthritis. Use of molecular diagnostic methods increases the identification of K. kingae in osteoarticular infections.