DIAGNOSING Kingella kingae OSTEOARTICULAR INFECTIONS IN YOUNG

CHILDREN VIA SPECIFIC OROPHARAYNGEAL SWAB PCR

R. ANDERSON1, V. DUBOIS-FERRIÈRE1, A. CHERKAOUI2, S MANZANO3, J. SCHRENZEL2, D. CERONI1

1SERVICE OF PEDIATRIC ORTHOPEDICS, 2SERVICE OF INFECTIOUS DISEASES, 3 EMERGENCY ROOM, UNIVERSITY HOSPITAL OF GENEVA, SWITZERLAND

Major cause of osteoarticular infections (OAI) in children under 4 years.

Belongs to the normal oropharyngeal flora (8-9% asymptomatic carriers)

Colonization of the oropharynx is a prerequisite for invasive infections which is mediated by the production of a potent RTX cytotoxin.

However diagnosing OAI caused by K. kingae remain challenging (mild clinical, biological and radiological signs and difficult germ cultivation).

Background

Kingella kingae:

Background

Study Aim To investigate whether a specific oropharyngeal swab real time

PCR (oropharyngeal K. kingae PCR) could improve the recognition of K. kingae OAI in young children.

Specific real time PCR targeting the RTX toxin coding DNA of K. kingae

Prospective cohort study of all young children presenting with atraumatic osteoarticular complaints between 2008 and 2011 to our emergency room.

Methods

EnrolmentClinical evaluation

1st phase investigations 2nd phase

diagnostic investigations

• Atraumatic OA complaints

• Age 6-48 months

• Clinical evaluation • CBC, CRP, VS, blood culture • Oropharyngeal K. kingae PCR

• MRI • Infection site puncture• Culture, broad range PCR• K. kingae PCR on osteo-

articular aspirate

Findings suggestive for OAI

Results

K. kingae OAI

30 cases

OAI (other)

1 case

no OAI

83 cases

H. Influenzae

123 patients enrolled

30 orophary. K. kingae PCR +

MRI consistent with OAI despite negative

microbiology

suspected OAI

9 cases

8 orophary. K. kingae PCR +

76 orophary. K. kingae PCR -

9 orophary. K. kingae PCR +

Excluded from statistical analysis

Results

Diagnostic performances of the oropharyngeal swab K. kingae specific PCR test (95% CI)

Sensitivity 100% (88.4; 100)

Specificity 90.5% (82.1; 95.8)

Positive predictive value 78.9% (62.7; 90.4)

Negative predictive value 100% (95.5; 100)

K. kingae is the 1st microorganism responsible for OAI in children under 4 years (>95% in this study)

Detection of K. kingae DNA in oropharyngeal swabs of children with clinical findings of OAI is predictive for K kingae OAI and negative result excludes OAI caused by this bacteria.

A valuable non invasive diagnostic tool which may improve the recognition of K. kingae OAI among young children.

Conclusions

Implementation of oropharyngeal K.kingae PCR as diagnostic tool for OAI in our setting:

Changed our diagnostic approach

Faster recognition of OAI in young children

Improved therapeutic management

Increased recognition of OAI due to K. kingae

Clinical perspecti ves

Thank you for your

attention