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

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.

Pharyngeal Colonization by Kingella kingae, Transmission, and Pathogenesis of Invasive Infections: A Narrative Review

With the appreciation of Kingella kingae as a prime etiology of osteoarticular infections in young children, there is an increasing interest in the pathogenesis of these diseases. The medical literature on K. kingae’s colonization and carriage was thoroughly reviewed. Kingella kingae colonizes the oropharynx after the second life semester, and its prevalence reaches 10% between the ages of 12 and 24 months, declining thereafter as children reach immunological maturity. Kingella kingae colonization is characterized by the periodic substitution of carried organisms by new strains. Whereas some strains frequently colonize asymptomatic children but are rarely isolated from diseased individuals, others are responsible for most invasive infections worldwide, indicating enhanced virulence. The colonized oropharyngeal mucosa is the source of child-to-child transmission, and daycare attendance is associated with a high carriage rate and increased risk of invasive disease. Kingella kingae elaborates a potent repeat-in-toxin (RTXA) that lyses epithelial, phagocytic, and synovial cells. This toxin breaches the epithelial barrier, facilitating bloodstream invasion and survival and the colonization of deep body tissues. Kingella kingae colonization and carriage play a crucial role in the person-to-person transmission of the bacterium, its dissemination in the community, and the pathogenesis of invasive infections.

Kingella kingae RtxA Cytotoxin in the Context of Other RTX Toxins

The Gram-negative bacterium Kingella kingae is part of the commensal oropharyngeal flora of young children. As detection methods have improved, K. kingae has been increasingly recognized as an emerging invasive pathogen that frequently causes skeletal system infections, bacteremia, and severe forms of infective endocarditis. K. kingae secretes an RtxA cytotoxin, which is involved in the development of clinical infection and belongs to an ever-growing family of cytolytic RTX (Repeats in ToXin) toxins secreted by Gram-negative pathogens. All RTX cytolysins share several characteristic structural features: (i) a hydrophobic pore-forming domain in the N-terminal part of the molecule; (ii) an acylated segment where the activation of the inactive protoxin to the toxin occurs by a co-expressed toxin-activating acyltransferase; (iii) a typical calcium-binding RTX domain in the C-terminal portion of the molecule with the characteristic glycine- and aspartate-rich nonapeptide repeats; and (iv) a C-proximal secretion signal recognized by the type I secretion system. RTX toxins, including RtxA from K. kingae, have been shown to act as highly efficient 'contact weapons' that penetrate and permeabilize host cell membranes and thus contribute to the pathogenesis of bacterial infections. RtxA was discovered relatively recently and the knowledge of its biological role remains limited. This review describes the structure and function of RtxA in the context of the most studied RTX toxins, the knowledge of which may contribute to a better understanding of the action of RtxA in the pathogenesis of K. kingae infections.

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.

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 3cases 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 3index cases and 5of the 6daycare attendees. Cultures were negative in all cases. After administration of prophylactic antibiotics, 3toddlers 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.

Outbreaks of Kingella kingae Infections in Daycare Centers Suggest Tissue Tropism of the Causative Strains

BACKGROUND

Although Kingella kingae is recognized as an important pediatric pathogen, our knowledge of the virulence factors involved in the invasion of specific host's tissues is limited. Outbreaks of K kingae infections in daycare centers represent natural experiments in which a single virulent strain, introduced into a cohort of susceptible young children, causes multiple infections. If K kingae strains exhibit tissue tropism, the syndromes observed in a given cluster of cases would be relatively homogeneous.

METHODS

Clinical data of all the K kingae outbreaks known to date were gathered and analyzed. The clinical syndromes diagnosed in the affected attendees were classified as septic arthritis, osteomyelitis, tenosynovitis, soft tissue infection, bacteremia with no focal disease, endocarditis, and meningitis, and computed separately. To assess the similarity of the clinical syndromes detected within outbreaks, we used the Cramer V statistic, which is a measure of the association between 2 nominal variables and, for the purposes of the study, between the detected clinical syndromes and the outbreaks.

RESULTS

A total of 23 outbreaks involving 61 attendees were identified. The mean±SD attack rate in the affected classrooms was 15.8% ± 4.8%, and the K kingae colonization rate among the attendees was 54.8% ± 25.3%. Seventy-two separate foci of infection were diagnosed. Osteomyelitis and septic arthritis were the most common clinical syndromes and were diagnosed in 26 children each, followed by tenosynovitis in 4 children. The clinical syndromes diagnosed among attendees to the same classroom showed a statistically significant tendency to be similar (P = .015).

CONCLUSIONS

The distribution of clinical syndromes in clusters of K kingae infections differs from that of sporadic cases. The causative strains combine enhanced virulence and high transmissibility, and show tropism toward bones, joints, and tendon sheaths. This information can be used to identify virulence factors associated with invasion of these specific host tissues.

Management of an outbreak of invasive Kingella kingae skeletal infections in a day care center

BACKGROUND

Kingella kingae (Kk) is frequently responsible for invasive skeletal infections in children aged 3-36months. However, few outbreaks of invasive Kk infections in day care centers have been reported. The objective of the present study was to describe (a) the clinical and laboratory data recorded during an outbreak of invasive Kk skeletal infections, and (b) the management of the outbreak.

METHOD

Four children from the same day care center were included in the study May and June 2019. We retrospectively analyzed the children's clinical presentation and their radiological and laboratory data. We also identified all the disease control measures taken in the day care center.

RESULTS

We observed cases of septic arthritis of the wrist (case #1), shoulder arthritis (case #2), knee arthritis (case #3) ans cervical spondylodiscitis (case #4). All cases presented with an oropharyngeal infection and concomitant fever prior to diagnosis of the skeletal infection. All cases were misdiagnosed at the initial presentation. The mean (range) age at diagnosis was 10.75months (9-12). The three patients with arthritis received surgical treatment. All patients received intravenous and then oral antibiotics. In cases 1 and 2, Kk was detected using real-time PCR and a ST25-rtxA1 clone was identified. The outcome was good in all four cases. Four other children in the day care center presented with scabies during this period and were treated with systemic ivermectin. The Regional Health Agency was informed, and all the parents of children attending the day care center received an information letter. The day care center was cleaned extensively.

CONCLUSION

Our results highlight the variety of features of invasive skeletal Kk infections in children and (given the high risk of transmission in day care centers) the importance of diagnosing cases as soon as possible.

Vertical Stratification in Urban Green Space Aerobiomes

BACKGROUND

Exposure to a diverse environmental microbiome is thought to play an important role in "educating" the immune system and facilitating competitive exclusion of pathogens to maintain human health. Vegetation and soil are key sources of airborne microbiota--the aerobiome. A limited number of studies have attempted to characterize the dynamics of near surface green space aerobiomes, and no studies to date have investigated these dynamics from a vertical perspective. Vertical stratification in the aerobiome could have important implications for public health and for the design, engineering, and management of urban green spaces.

OBJECTIVES

The primary objectives of this study were to: a) assess whether significant vertical stratification in bacterial species richness and evenness (alpha diversity) of the aerobiome occurred in a parkland habitat in Adelaide, South Australia; b) assess whether significant compositional differences (beta diversity) between sampling heights occurred; and c) to preliminarily assess whether there were significant altitudinal differences in potentially pathogenic and beneficial bacterial taxa.

METHODS

We combined an innovative columnar sampling method at soil level, 0.0, 0.5, 1.0, and 2.0 m , using passive petri dish sampling to collect airborne bacteria. We used a geographic information system (GIS) to select study sites, and we used high-throughput sequencing of the bacterial 16S rRNA gene to assess whether significant vertical stratification of the aerobiome occurred.

RESULTS

Our results provide evidence of vertical stratification in both alpha and beta (compositional) diversity of airborne bacterial communities, with diversity decreasing roughly with height. We also found significant vertical stratification in potentially pathogenic and beneficial bacterial taxa.

DISCUSSION

Although additional research is needed, our preliminary findings point to potentially different exposure attributes that may be contingent on human height and activity type. Our results lay the foundations for further research into the vertical characteristics of urban green space aerobiomes and their implications for public health and urban planning. https://doi.org/10.1289/EHP7807.

Pediatric Infectious Prepatellar Bursitis with Kingella kingae

We present the first reported case of septic prepatellar bursitis with Kingella kingae in a 2-year-old female. Although it is a well-established cause of osteoarticular infections in the pediatric population, K. kingae has never been reported as the etiology for septic bursitis. A high index of suspicion is required for the diagnosis given that this organism is difficult to culture and isolate using standard laboratory methods. Our diagnosis was established through bursal fluid analysis, though oropharyngeal polymerase chain reaction (PCR) may be also be considered. Our case also builds upon prior literature suggesting that the pathophysiology of septic bursitis in children differs from that of the adult and may be more comparable to that of pediatric osteomyelitis. As an organism of increasing prevalence, K. kingae should remain high on the differential for osteoarticular or periarticular infections when cultures fail to isolate a distinct pathogen. Early diagnosis and a formal irrigation and debridement, if warranted, are crucial in preventing devastating complications of untreated septic bursitis.

The first report on epidemiology of oropharyngeal Kingella kingae carriage in Scandinavian children: K. kingae carriage is very common in children attending day care facilities in Western Norway

Kingella kingae colonizes the upper airways in children and has been recognized as the most common causative agent of osteoarticular infections (OAI) in children below 4 years of age. This is the first Scandinavian study to investigate oropharyngeal K. kingae carriage in healthy children. From June 2015 to August 2016, we recruited 198 healthy children aged 11-14 months from routine consultations at health promotion centers in Hordaland County, Norway for a cross-sectional study. After their parents had provided informed consent; demographic data were registered, and an oropharyngeal swab was collected. The oropharyngeal swab was analyzed with a real-time PCR assay specific to K. kingae targeting the RTX toxin locus. Results showed an asymptomatic carriage rate of 12.6%. A striking and highly significant difference was observed between the children that had started attending day care facilities as compared with children still being at home (33.33% vs 8.5%; p < 0.001). K. kingae is prevalent in young children in Norway. This study emphasize that K. kingae should be considered an important etiological agent in OAI. Transmission seems to be facilitated in day care facilities. The correlation between oropharyngeal carriage and OAI needs to be further explored.

Diagnosis and Management of Infectious Arthritis in Children

PURPOSE OF REVIEW

Septic arthritis is limb and life-threatening condition which necessitates rapid diagnosis and treatment. It is important for a medical practitioner to be familiar with this condition. This review summarizes the epidemiology, risk factors, diagnosis and differential diagnosis, complications, as well as treatment and the following-up of this condition.

RECENT FINDINGS

Different causative organisms require unique diagnostic and treatment approaches. Establishing the diagnosis often requires multiple diagnostic modalities, some of which are new and innovative. Differential diagnosis requires excluding non-infectious inflammatory causes, such as reactive arthritis, juvenile rheumatoid arthritis, transient synovitis, and pericapsular pyomyositis. There is no consensus regarding the nature or duration of pharmacological or surgical treatment. Treatment includes administration of appropriate antimicrobial therapy and including the use of steroids and drainage. The most common complications are osteonecrosis of the femoral head and chronic osteomyelitis. Complications of septic arthritis are mostly due to a missed diagnosis. Further studies are required to better evaluate the diagnostic and therapeutic choice.

Imaging of Kingella kingae musculoskeletal infections in children: a series of 5 cases

PURPOSE

Kingella kingae musculoskeletal infections continue to be under-diagnosed and there remains a paucity of literature on its imaging features. The purpose of this manuscript is to review the imaging, clinical, and laboratory findings of microbiology-proven K. kingae infections.

MATERIALS AND METHODS

A retrospective review of musculoskeletal infections between January 1, 2013 and Dec 31, 2016 yielded 134 patients from whom 5 patients had confirmed K. kingae infections (3 boys and 2 girls, mean age of 16 months, range 9-38 months). Picture archiving and communication system and electronic medical records were reviewed.

RESULTS

At presentation, none of the patients had a fever and not all patients had abnormal inflammatory markers. Three patients had septic arthritis (2 knee and 1 sternomanubrial joints), one had epiphyseal osteomyelitis, and one had lumbar spondylodiscitis. The case of epiphyseal osteomyelitis of the distal humerus also had elbow joint involvement. A combination of radiography (n = 4), ultrasound (n = 2), and magnetic resonance (MR) imaging (n = 5) were performed. Prominent synovial thickening was observed for both knee and elbow joints and extensive regional myositis for all except for the patient with sternomanubrial joint infection. The diagnosis of K. kingae infection resulted in a change in the antibiotic regimen in 80% of the patients.

CONCLUSION

Disproportionate synovial thickening, prominent peri-articular myositis, and/or characteristic sites of involvement demonstrating imaging features of infection or inflammation in a young child with mild infectious symptoms and elevated inflammatory markers should invoke the possibility of an underlying K. kingae infection.

Paediatric Bone and Joint Infections in French Guiana: A 6 Year Retrospective Review

The epidemiology of paediatric bone and joint infections from South America is poorly known. We herein report a retrospective study conducted in whole French Guiana from January 2010 to December 2015. Medical charts of 55 previously healthy children were analysed, identifying 27 with osteomyelitis, 22 with septic arthritis and 6 with multifocal infections and/or osteoarthritis. The male:female ratio was 2.2:1, and the mean age was 7.5 years. Eighty percent children were ≥36 months old who had predominantly osteomyelitis related to methicillin-susceptible Staphylococcus aureus (p < 0.05) in the course of neglected skin infections. Five children presented with multi-systemic infections resulting in one fatality, mainly caused by S. aureus producing Panton-Valentine leucocidin (p < 0.01). In contrast, children aged 6-36 months had more likely culture-negative infections (p < 0.05), septic arthritis and mild clinical and biological features. Further prospective studies are required to better guide rational diagnostic and therapeutic strategies.

Investigation of Kingella kingae Invasive Infection Outbreaks in Day Care Facilities: Assessment of a Rapid Genotyping Tool Targeting the DNA Uptake Sequence

Outbreaks of Kingella kingae invasive infections have recently been reported in day care centers. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) revealed that although the invasive strains had widespread dissemination in the day care population, less virulent strains were also circulating in the facilities. However, these typing tools are costly, time-consuming, and labor-intensive and provide delayed results. A study was conducted to assess the performance of a rapid and cost-effective genotyping tool targeting the DNA uptake sequence (DUS) in the investigation of outbreaks of K. kingae disease. DUS typing (DUST) patterns of each strain from 7 different clusters were compared to distinguish genotypically linked strains from others. PFGE and, when available, MLST results were used as gold standards. DUST was assessed on 80 K. kingae isolates from Nir-Itzhak (n = 14), Tel-Nof (n = 14), Palmahim (n = 5), Umm-al-Fahm (n = 7), Eilat (n = 8), Nevatim (n = 15) in Israel and Paris, France (n = 17). A unique DUST pattern was involved in the Nir-Itzhak, Palmahim, Umm-al-Fahm, and Paris episodes. Two DUST patterns were found in Eilat, whereas at least 3 were identified in the Tel-Nof and Nevatim episodes. In total, 11 (13.8%) children carried a K. kingae isolate that differed from the outbreak strain. These results were concordant with those obtained with the traditional PFGE and MLST methods. DUST appears to be sensitive and specific in distinguishing the invasive outbreak strain from others in asymptomatic carriers and could be useful to limit unnecessary exposure of the entire day care population to selective antibiotic pressure.

Low prevalence of Kingella kingae carriage in children aged 6-48 months in Sydney, Australia

AIM

A prospective observational study was conducted to estimate the prevalence of oropharyngeal carriage of Kingella kingae in healthy Australian pre-school children.

METHODS

Screening for carriage of K. kingae as well as Streptococcus pyogenes, Streptococcus pneumoniae, Streptococcus agalactiae, Staphylococcus aureus, Haemophilus influenzae, and K. kingae was undertaken using a single bacterial throat swab taken from well children aged 6 months to 4 years. Standard laboratory procedures were used for culture and identification of organisms.

RESULTS

One hundred children were enrolled between October and December 2014 at the Children's Hospital at Westmead. Median age was 24.0 months (range 6.1-48.8 months); 52 children were male and 36 attended day-care facilities. Forty-one children had siblings aged less than 5 years and 67 children had siblings of any age. K. kingae oropharyngeal carriage was not detected in any of the children. Rates of carriage of other organisms were: 30% S. aureus, 21% H. influenzae, 2% S. pneumoniae and 2% S. pyogenes. Thirty-eight children were colonised with Kingella denitrificans.

CONCLUSIONS

Our results suggest that prevalence of K. kingae carriage in pre-school children in Sydney is very low and support local and national guidelines that recommend flucloxacillin as empiric first-line therapy for children with osteoarticular infections. Studies conducted over the winter months and in other Australian centres could help answer outstanding questions regarding differences in carriage rates of K. kingae in children.

Kingella kingae-Associated Pediatric Osteoarticular Infections: An Overview of 566 Reported Cases

This study aimed to summarize clinical experience with Kingella kingae-associated pediatric osteoarticular infections (OAIs). We reviewed 566 cases in the English literature from 2000 to June 2014. More than 80% of the patients were diagnosed between 4 months and 4 years of age, and the male to female ratio was 1.14:1. The most frequent preceding illness was upper respiratory tract infections (82%). The top 3 OAIs types were septic arthritis (73.1%), osteomyelitis (15.7%), and spondylodiscitis (5.4%), and the most affected sites of these types were knee (46%), calcaneus (20%), and L4/5 disc (70%). All cases where polymerase chain reaction (PCR) technique was used were PCR positive, no reported cases of positive cultures for K kingae with negative PCR. The duration of antibiotics use ranged from 2 to 4 weeks. Beta-lactam antibiotics were the most frequently used intravenously and orally. The clinical efficacy was favorable.

Patterns of Kingella kingae Disease Outbreaks

BACKGROUND

Kingella kingae outbreaks occur sporadically in childcare centers but remain poorly understood and difficult to identify.

METHODS

To provide the basis of a better knowledge of K. kingae outbreaks patterns that may help to guide identification and management strategies, we collected epidemiological, clinical and laboratory data from all reported K. kingae outbreaks, and those from 2 new Israel outbreaks in 2014.

RESULTS

Nine outbreaks were identified in the USA, Israel and France from 2003 to 2014. Twenty-seven children with a median age of 14 ± 4.1 months were affected, male:female ratio of 1.4:1. Outbreaks demonstrated seasonal patterns from the 10th to the 45th weeks, a mean duration of 13.1 ± 8.4 days, a mean attack rate of 17.3 ± 5.1% and a case-fatality rate of 3.7% (1/27). Seventy-four percentage of children had fever (20/27), and the mean values of white blood cell count and C-reactive protein level were 14.6 ± 4.5 × 10/L and 23.8 ± 24.1 mg/L, respectively. Osteoarticular infections accounted for 88.9% of cases (24/27), bacteremia 7.4% (2/27), endocarditis 3.7% (1/27) and meningitis 3.7% (1/27). Specific real-time polymerase chain reaction demonstrated higher performance than culture methods in the diagnosis of case patients and investigations of oropharyngeal K. kingae carriage among close contacts, and multilocus sequence typing methods revealed that ST-6 and ST-25 invasive strains were responsible for multiple country-dependent outbreaks. Coviral infections were identified in the majority of K. kingae outbreaks, notably those causing oral ulcers.

CONCLUSIONS

K. kingae outbreaks displayed severe K. kingae diseases that were poorly confirmed with culture methods. We argue for the use of genomic technologies to investigate further K. kingae outbreaks.

A Retrospective Case-Series of Children With Bone and Joint Infection From Northern Australia

Our clinical workload as infectious diseases pediatricians in northern Australia is dominated by complicated bone and joint infections in indigenous children. We reviewed the clinical presentation, microbiology, management, and outcomes of children presenting to Royal Darwin Hospital with bone and joint infections between 2010 and 2013, and aimed to compare severity and incidence with other populations worldwide.A retrospective audit was performed on children aged 0 to 18 years who were admitted to Royal Darwin Hospital between 1 January 2010 and 31 December 2013 with a bone and joint infection.Seventy-nine patients were identified, of whom 57 (72%) had osteomyelitis ± associated septic arthritis and 22 (28%) had septic arthritis alone. Sixty (76%) were indigenous Australians. The incidence rate of osteomyelitis for indigenous children was 82 per 100,000 children. Staphylococcus aureus was the confirmed pathogen in 43/79 (54%), of which 17/43 (40%) were methicillin resistant. Median length of stay was 17 days (interquartile range: 10-31 days) and median length of IV antibiotics was 15 days (interquartile range: 6-24 days). Fifty-six (71%) required at least 1 surgical procedure. Relapse within 12 months was documented in 12 (15%) patients.We report 3 key findings: osteomyelitis incidence in indigenous children of northern Australia is amongst the highest reported in the world; methicillin-resistant S aureus accounts for 36% of osteomyelitis with a positive microbiological diagnosis; and the severity of disease requires extended antibiotic therapy. Despite this, 15% of the cohort relapsed within 12 months and required readmission.

Outbreaks of Invasive Kingella kingae Infections in Closed Communities

OBJECTIVES

To 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.

STUDY DESIGN

The preschool-aged population of communities with clusters of Kingella cases had oropharyngeal cultures performed. K kingae isolates from infected patients and healthy contacts were genotyped by pulsed field gel electrophoresis to determine the spread of outbreak strains.

RESULTS

The affected closed communities (3 military bases and 1 "kibbutz" commune) were characterized by tight social and family networks and intensive mingling. The outbreaks affected 9 of 51 attendees (attack rate: 17.6%) age 8-19 months (median: 12 months), within a 21-day period. Cases included skeletal system infections (n = 8) and bacteremia (n = 1); K kingae isolates were confirmed by the use of blood culture vials and selective media. Clinical presentation was mild and acute-phase reactants were usually normal or only moderately elevated. Thirty out of 55 (54.5%) asymptomatic children carried the outbreak strains. Analysis of the 3 clusters in which the entire preschool-aged population was cultured revealed that 31 of 71 (43.7%) children younger than 24 months of age were colonized with K kingae organisms compared with 8 of 105 (7.6%) older children (P < .001).

CONCLUSIONS

Clusters of invasive K kingae infections characterized by sudden onset, high attack rate, and wide dissemination of the outbreak strain can occur in daycare facilities and closed communities. Because the mild clinical presentation of invasive K kingae infections and the fastidious nature of the organism, a high index of suspicion and use of sensitive detection methods are recommended.

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.

Pore forming activity of the potent RTX-toxin produced by pediatric pathogen Kingella kingae: Characterization and comparison to other RTX-family members

Pediatric septic arthritis in patients under age of four is frequently caused by the oral Gram-negative bacterium Kingella kingae. This organism may be responsible for a severe form of infective endocarditis in otherwise healthy children and adults. A major virulence factor of K. kingae is RtxA, a toxin that belongs to the RTX (Repeats-in-ToXin) group of secreted pore forming toxins. To understand the RtxA effects on host cell membranes, the toxin activity was studied using planar lipid bilayers. K. kingae strain PYKK081 and its isogenic RtxA-deficient strain, KKNB100, were tested for their ability to form pores in artificial membranes of asolectin/n-decane. RtxA, purified from PYKK081, was able to rapidly form pores with an apparent diameter of 1.9nm as measured by the partition of nonelectrolytes in the pores. The RtxA channels are cation-selective and showed strong voltage-dependent gating. In contrast to supernatants of PYKK081, those of KKNB100 did not show any pore forming activity. We concluded that RtxA toxin is the only secreted protein from K. kingae forming large channels in host cell membranes where it induces cation flux leading to programmed cell death. Furthermore, our findings suggested that the planar lipid bilayer technique can effectively be used to test possible inhibitors of RTX toxin activity and to investigate the mechanism of the toxin binding to the membrane.

An outbreak of Kingella kingae infections associated with hand, foot and mouth disease/herpangina virus outbreak in Marseille, France, 2013

BACKGROUND

Outbreaks of invasive Kingella kingae infections recently emerged as a new public health concern in daycare centers in Europe, USA and Israel. Despite this, no trigger factor has been yet identified, preventing the setting up of rational measures of control and prevention. We report an outbreak of K. kingae infections associated with hand, foot and mouth disease/herpangina outbreak, and we define the research and policy priorities.

METHODS

From April 22 to May 07, 2013, 5 toddlers presented successive osteo-articular infections in a daycare center in Marseille, France. Real-time polymerase chain reaction targeting the cpn60 gene of K. kingae was used to investigate suspected cases and the prevalence of oropharyngeal K. kingae carriage of their close contacts.

RESULTS

The attack rate of the K. kingae infections outbreak was 23.7% (5/21) with no fatality. Positive real-time polymerase chain reaction targeting the cpn60 gene of K. kingae confirmed the diagnosis in 3 cases and revealed a rate of K. kingae oropharynx carriage in the index classroom of 94.4% (17/18) among daycare attendees not given antibiotic during the previous month, and of 76.9% (10/13) among staff in close contact. The eradication rate of K. kingae was 21.4% (3/14) among classmates after oral administration of rifampicin, and eradication occurred spontaneously in 83.3% (5/6) of the staff. Clinical and epidemiological features of the herpangina outbreak were consistent with that of an emerging European Coxsackievirus-A6 outbreak.

CONCLUSIONS

Hand, foot and mouth disease/herpangina virus outbreak enables triggering a K. kingae infections outbreak. Our findings offer support for new guidelines of K. kingae infections outbreaks management and emphasize the need for further research.

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.

Major intercontinentally distributed sequence types of Kingella kingae and development of a rapid molecular typing tool

Although Kingella kingae is the most common etiology of osteoarticular infections in young children, is a frequent cause of bacteremia in those younger than 4 years, and has been involved in clusters of invasive infections among daycare center attendees, the population structure of the species has not been systematically studied. Using multilocus sequence typing, we investigated the genetic diversity of the largest intercontinental collection of K. kingae strains to date. To facilitate typing of bacterial isolates, we developed a novel genotyping tool that targets the DNA uptake sequence (DUS). Among 324 strains isolated from asymptomatic carriers and patients from Israel, Europe, North America, and Australia with various invasive forms of the disease from 1960 to 2013, we identified 64 sequence types (STs) and 12 ST complexes (STcs). Five predominant STcs, comprising 72.2% of all strains, were distributed intercontinentally. ST-6 was the most frequent, showing a worldwide distribution, and appeared genotypically isolated by exhibiting few neighboring STs, suggesting an optimal fitness. ST-14 and ST-23 appeared to be the oldest groups of bacteria, while ST-25 probably emerged more recently from the highly evolutive ST-23. Using the DUS typing method, randomly chosen isolates were correctly classified to one of the major STcs. The comprehensive description of K. kingae evolution would help to detect new emerging clones and decipher virulence and fitness mechanisms. The rapid and reproducible DUS typing method may serve in the initial investigation of K. kingae outbreaks.

Genotyping, local prevalence and international dissemination of β-lactamase-producing Kingella kingae strains

β-lactamase production has been sporadically reported in the emerging Kingella kingae pathogen but the phenomenon has not been studied in-depth. We investigated the prevalence of β-lactamase production among K. kingae isolates from different geographical origins and genetically characterized β-lactamase-producing strains. Seven hundred and seventy-eight isolates from Iceland, the USA, France, Israel, Spain and Canada were screened for β-lactamase production and, if positive, were characterized by PFGE and MLST genotyping, as well as rtxA, por, blaTEM and 16S rRNA sequencing. β-lactamase was identified in invasive strains from Iceland (n=4/14, 28.6%), the USA (n=3/15, 20.0%) and Israel (n=2/190, 1.1%) and in carriage strains in the USA (n=5/17, 29.4%) and Israel (n=66/429, 15.4%). No French, Spanish or Canadian isolates were β-lactamase producers. Among β-lactamase producers, a perfect congruency between the different typing methods was observed. Surprisingly, all US and Icelandic β-lactamase-producing isolates were almost indistinguishable, belonged to the major international invasive PFGE clone K/MLST ST-6, but differed from the four genetically unrelated Israeli β-lactamase-producing clones. Representative strains of different genotypes produced the TEM-1 enzyme. K. kingae β-lactamase producers exhibit a clear clonal distribution and have dissimilar invasive potential. The presence of the enzyme in isolates belonging to the major worldwide invasive clone K/ST-6 highlights the possible spread of β-lactam resistance, and emphasizes the importance of routine testing of all K. kingae clinical isolates for β-lactamase production.

Outbreaks of Kingella kingae infections in daycare facilities

During the past decade, transmission of the bacterium Kingella kingae has caused clusters of serious infections, including osteomyelitis, septic arthritis, bacteremia, endocarditis, and meningitis, among children in daycare centers in the United States, France, and Israel. These events have been characterized by high attack rates of disease and prevalence of the invasive strain among asymptomatic classmates of the respective index patients, suggesting that the causative organisms benefitted from enhanced colonization fitness, high transmissibility, and high virulence. After prophylactic antibacterial drugs were administered to close contacts of infected children, no further cases of disease were detected in the facilities, although test results showed that some children still carried the bacterium. Increased awareness of this public health problem and use of improved culture methods and sensitive nucleic acid amplification assays for detecting infected children and respiratory carriers are needed to identify and adequately investigate outbreaks of K. kingae disease.

RTX toxin plays a key role in Kingella kingae virulence in an infant rat model

Kingella kingae is a human oral bacterium that can cause diseases of the skeletal system in children and infective endocarditis in children and adults. K. kingae produces a toxin of the RTX group, RtxA. To investigate the role of RtxA in disease pathogenesis in vivo, K. kingae strain PYKK081 and its isogenic RtxA-deficient strain KKNB100 were tested for their virulence and pathological consequences upon intraperitoneal injections in 7-day-postnatal (PN 7) rats. At the doses above 8.0 × 10(6) cells/animal, PYKK081 was able to cause a fatal illness, resulting in rapid weight loss, bacteremia, and abdominal necrotic lesion formation. Significant histopathology was observed in thymus, spleen, and bone marrow. Strain KKNB100 was less toxic to animals. Neither weight loss, bacteremia, nor histopathological changes were evident. Animals injected with KKNB100 exhibited a significantly elevated circulating white blood cell (WBC) count, whereas animals injected with PYKK081 had a WBC count that resembled that of the uninfected control. This observation parallels the subtleties associated with clinical presentation of K. kingae disease in humans and suggests that the toxin contributes to WBC depletion. Thus, our results demonstrate that RtxA is a key K. kingae virulence factor. Furthermore, our findings suggest that the PN 7 rat can serve as a useful model for understanding disease caused by K. kingae and for elucidating diagnostic parameters in human patients.

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.

[A case of osteomyelitis due to Kingella kingae]

Kingella species including K. kingae are non-motile coccobacilli or short straight rods, and their normal habitats appear to be the upper respiratory and oropharyngeal tracts of humans. In recent years, K. kingae strains have been increasingly recognized as common causes of invasive infections in children at the age of less than 4 years. In Japan, however, invasive K. kingae infections including osteomyelitis have rarely been described. We incidentally encountered isolation of a K. kingae strain from intraoperatively obtained specimens from a previously healthy 44-month-old boy. He first consulted a nearby medical facility and a suspected diagnosis of osteomyelitis was made, after which the patient was then transferred to our Nagano Children's hospital. There was evidence of inflammation in his right calcaneus and toe walking was noted. He was treated with surgical drainage. An isolate grown on sheep blood agar with positive oxidase and negative catalase was biochemically characterized with the ID-Test HN20 (Nissui Pharmaceutical Co., Ltd., Tokyo, Japan) kit system together with genetic examinations involving sequencing the 16S rRNA gene, and the infection was finally identified as K. kingae. The patient was successfully treated with cefotiam (CTM) for the first 7 days followed by the administration of trimethoprim-sulfamethoxazole (ST) for an additional 2 months. The K. kingae isolate was confirmed as a sure causative pathogen by observing that the serum showed high agglutinin titers against the isolate. Accumulation of the case reports in Japan with the isolation of this species is essential for clarifying invasive infections due to K. kingae. Our case report is a noteworthy and useful piece of information.

Characterization of TEM-1 β-Lactamase-Producing Kingella kingae Clinical Isolates

Kingella kingae is a human pathogen that causes pediatric osteoarticular infections and infective endocarditis in children and adults. The bacterium is usually susceptible to β-lactam antibiotics, although β-lactam resistance has been reported in rare isolates. This study was conducted to identify β-lactam-resistant strains and to characterize the resistance mechanism. Screening of a set of 90 K. kingae clinical isolates obtained from different geographic locations revealed high-level resistance to penicillins among 25% of the strains isolated from Minnesota and Iceland. These strains produced TEM-1 β-lactamase and were shown to contain additional ≥50-kb plasmids. Ion Torrent sequencing of extrachromosomal DNA from a β-lactamase-producing strain confirmed the plasmid location of the bla_TEM gene. An identical plasmid pattern was demonstrated by multiplex PCR in all β-lactamase producers. The porin gene's fragments were analyzed to investigate the relatedness of bacterial strains. Phylogenetic analysis revealed 27 single-nucleotide polymorphisms (SNPs) in the por gene fragment, resulting in two major clusters with 11 allele types forming bacterial-strain subclusters. β-Lactamase producers were grouped together based on por genotyping. Our results suggest that the β-lactamase-producing strains likely originate from a single plasmid-bearing K. kingae isolate that traveled from Europe to the United States, or vice versa. This study highlights the prevalence of penicillin resistance among K. kingae strains in some regions and emphasizes the importance of surveillance for antibiotic resistance of the pathogen.

A case of Kingella kingae endocarditis complicated by native mitral valve rupture

We report a case of Kingella kingae endocarditis in a patient with a history of recent respiratory tract infection and dental extraction. This case is remarkable for embolic and vasculitic phenomena in association with a large valve vegetation and valve perforation. Kingella kingae is an organism known to cause endocarditis, however early major complications are uncommon. Our case of Kingella endocarditis behaved in a virulent fashion necessitating a combined approach of intravenous antibiotic therapy and a valve replacement. It highlights the importance of expedited investigation for endocarditis in patients with Kingella bacteraemia.

Investigation of an outbreak of osteoarticular infections caused by Kingella kingae in a childcare center using molecular techniques

We describe an outbreak of 5 osteoarticular infections among 24 daycare center attendees. Polymerase chain reaction revealed Kingella kingae in the joint fluid of 1 child and in 85% of throat samples from healthy contacts. Multilocus sequence typing performed on the joint fluid and carriage isolates identified an unique sequence type. Rifampin failed to eradicate K. kingae carriage.

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.

Prevalence of pharyngeal carriage of Kingella kingae in young children and risk factors for colonization

The carriage rate of Kingella kingae among Jewish and Bedouin children living in southern Israel paralleled the age-related incidence of invasive infections. Age 6-29 months was a significant risk factor for K. kingae colonization in both ethnic groups; day-care attendance was a risk factor in Jewish children, whereas living in a shanty town was negatively associated with carriage in Bedouins.

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.

Small risk of osteoarticular infections in children with asymptomatic oropharyngeal carriage of Kingella kingae

The aim of this study was to evaluate the absolute risk for children younger than 4 years of age with asymptomatic oropharyngeal carriage of Kingella kingae to sustain an osteoarticular infection. The rate of K. kingae carriage in the oropharyngeal mucosa was 9% among healthy children, and the risk for an asymptomatic carrier to develop an osteoarticular infection due to K. Kingae was estimated to be lower than 1%.

Osteomielite hematogênica aguda em Pediatria: análise de casos atendidos em hospital universitário

OBJETIVO: Descrever a ocorrência, a evolução e o desfecho de pacientes com osteomielite hematogênica aguda na faixa etária pediátrica. MÉTODOS: Estudo descritivo de 21 casos de pacientes de zero a 14 anos com diagnóstico de osteomielite hematogênica aguda, em acompanhamento no Ambulatório de Infectologia Pediátrica da Escola Paulista de Medicina entre 2005 e 2009. A coleta de dados ocorreu pelo levantamento de prontuários. Realizaram-se a análise descritiva e o teste de correlação de Spearman, com intervalo de confiança de 95%. RESULTADOS: Foi identificada maior incidência no sexo masculino e em crianças maiores de cinco anos. Febre e dor foram os sintomas mais frequentes. Os ossos longos foram os mais acometidos. O principal agente etiológico identificado foi o Staphylococcus aureus. Em média, o tempo de sintomatologia até o diagnóstico foi de 9,7 dias, o de internação, 24,7 dias, e o total de antibioticoterapia foi de 71,7 dias. A resolução completa do quadro ocorreu em 71,4% dos casos, com permanência de sequelas em 28,6% deles, sendo a evolução para osteomielite crônica a principal delas. CONCLUSÕES: As características dos pacientes e da doença referentes a sexo, idade, etiologia e evolução mostram-se concordantes com o descrito na literatura. O tempo de tratamento foi de aproximadamente dez semanas, valor acima do habitualmente encontrado nos diferentes estudos. Não foram encontradas correlações significantes entre o tempo de sintomatologia até o diagnóstico, o tempo de internação e o tempo total de antibioticoterapia, havendo a limitação do tamanho da amostra.

Isolation of Kingella denitrificans from a corneal ulcer

PURPOSE

To report a case of a corneal ulcer caused by an unusual pathogen.

DESIGN

Case report.

METHODS

Clinical review describing initial presentation, course, and outcome of 1 patient with a corneal ulcer caused by Kingella denitrificans.

RESULTS

A 77-year-old man with a prior history of 4 penetrating keratoplasties in the right eye for herpes simplex virus keratitis presented with a 3-day history of a red painful right eye. On examination, he was found to have a corneal ulcer identified by culture as K. denitrificans.

CONCLUSIONS

Although Kingella spp. is not a common ocular pathogen, it can infect the cornea, especially when the host immune defense is altered.

Microbiological profile of haematogenous osteoarticular infections in children

INTRODUCTION

Staphylococcus aureus, Kingella kingae and β-hemolytic streptococcus are presently the most frequently identified bacteria in child haematogenous osteoarticular infection.

OBJECTIVE

To determine the microbiological profile (bacteria and antibiotic susceptibility) of osteoarticular infections in a paediatric hospital, so as to adapt treatment protocols to the ecology of the bacteria isolated.

PATIENTS AND METHODS

Prospective descriptive study, including children admitted for acute osteomyelitis or septic arthritis. A series of blood cultures was performed systematically on admission. In case of surgery, local samples were taken for bacteriology. Antibiotherapy was initiated and subsequently adapted to the bacteriological findings.

RESULTS

One hundred and six children were included. Thirty-five were under (Group 1) and 71 over 3 years of age (Group 2). Ninety-five underwent surgery. Peroperative samples were positive in 61 cases and blood culture in 23. Bacteria were isolated in 22 patients in G1. Extended-spectrum β-lactamase-producing Klebsiella pneumoniae was isolated in five neonates who had passed through intensive care. Staphylococcus aureus was the most frequently isolated bacterium in G2 (n=40), and was methicillin-resistant (MRSA) in six children.

DISCUSSION

Methicillin-susceptible Staphylococcus aureus was the most frequently isolated microorganism. Other than neonates who had passed through intensive care and the six patients with community-acquired MRSA infection, all isolated bacteria were susceptible to second-generation cephalosporins.

LEVEL OF EVIDENCE

II, prospective descriptive prognostic study.

Kingella kingae: an emerging pathogen in young children

Kingella kingae is being recognized increasingly as a common etiology of pediatric osteoarticular infections, bacteremia, and endocarditis, which reflects improved culture methods and use of nucleic acid-amplification techniques in clinical microbiology laboratories. K kingae colonizes the posterior pharynx of young children and is transmitted from child to child through close personal contact. Day care attendance increases the risk for colonization and transmission, and clusters of K kingae infections among day care center attendees have been reported. Key virulence factors in K kingae include type IV pili and a potent RTX toxin. In previously healthy children, >95% of K kingae infections are diagnosed between the ages of 6 and 48 months. Among children with underlying medical conditions, K kingae disease may occur at older ages as well. The clinical presentation of K kingae disease is often subtle and may be associated with normal levels of acute-phase reactants, which underscores the importance of a high index of suspicion. K kingae is usually susceptible to ß-lactam antibiotics, and infections typically respond well to medical treatment, with the exception of cases of endocarditis.