1.
An Introduction to
childhood Kingella
Kingae infections
Prof. Dr. Saad S Al Ani
Prof. of Pediatrics
Senior Pediatric consultant
Saad’s Kids Clinic
anahbaghdad@gmail.com

2.
Introduction
Kingella kingae: A type of bacteria
that has emerged from obscurity to
become known as an important cause
of invasive infections in young
children
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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3.
Kingella kingae
•Fastidious
•Facultative anaerobic
•β-hemolytic
•Appears as pairs or short chains of
gram-negative coccobacilli with
tapered ends
•Member of the Neisseriaceae family
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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https://www.researchgate.net/publication/233671839_Kingella_kingae_A_Pediatric_Pathogen_of_Increasing_Importance

4.
K. kingae is a recognized
commensal in the oropharynx of
young children particularly in
ages 6 to 48 months
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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El Houmami N, Minodier P, Dubourg G, et al. An outbreak
of Kingella kingae infections associated with hand, foot and mouth
disease/herpangina virus outbreak in Marseille, France,
2013. Pediatr Infect Dis J. 2015;34(3):246–250

5.
The clinical presentation of disease
due to Kingella kingae is often
subtle so that making the diagnosis
requires a high index of suspicion.
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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6.
Species of Kingella
There are four species of Kingella:
• K. kingae, the most common, is
part of the bacterial flora
• K. indologenes, K. denitrificans
both causing endocarditis
• K. oralis found in dental plaque
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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https://en.wikipedia.org/wiki/Kingella_kingae

7.
Routine laboratory tests may be normal
because the organism is difficult to
culture
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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https://en.wikipedia.org/wiki/Kingella_kingae

8.
Epidemiology
• Asymptomatically carried in the
posterior pharynx
• Colonization:
Usually starts after age 6 months
Reaches a prevalence of 10%
between 12 and 24 months
Decreases in older children
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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9.
Proposed pathogenesis of K. kingae infections
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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https://go.gale.com

10.
Associated infections
K. kingae invasive infections have
been associated with:
• Hand-foot-mouth disease
• Herpes simplex virus causing
stomatitis
• Varicella zoster virus
• Human rhinovirus
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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El Houmami N, Mirand A, Dubourg G, et al. Hand, foot and mouth disease and
Kingella kingae infections. Pediatr Infect Dis J. 2015;34(5):547–548

11.
Prerequisite for invasive disease
which is commonly triggered by
viral infections
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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El Houmami N, Minodier P, Dubourg G, et al. An outbreak
of Kingella kingae infections associated with hand, foot and mouth
disease/herpangina virus outbreak in Marseille, France,
2013. Pediatr Infect Dis J. 2015;34(3):246–250

12.
Transmission
• By close contact between young
children
• A recent reported increase in :
Oropharyngeal carriage rates
Outbreaks of invasive disease
involving the skeletal system in
day-care centers
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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13.
Epidemiology (Cont.)
Pharyngeal colonization plays a
crucial role in the transmission of
the organism through intimate
contact between siblings and
playmates
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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14.
Epidemiology (Cont.)
• Daycare attendance increases the risk
for colonization and transmission
• Clusters of invasive infection have
been reported in childcare facilities
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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15.
Epidemiology (Cont.)
Invasive K. kingae disease is most
frequently diagnosed in otherwise
healthy children between ages 6
months and 3 yr,
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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16.
Pathogenesis
K. kingae
by pili &
nonpilus adhesin
adherence of the organism to the
pharyngeal epithelium
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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17.
Pathogenesis (Cont.)
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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Gram-stain of a positive blood-culture vial from a child with K kingae bacteremia, which shows typical pairs and
short chains of Gram-negative coccobacilli (gray arrows). RBCs indicates red blood cells.
https://pediatrics.aappublications.org

18.
Pathogenesis (Cont.)
K. kingae secretes a potent
Repeats-in-Toxin (RTX) toxin
that exhibits deleterious activity to:
– Respiratory epithelial cells
– Macrophages
– Synoviocytes
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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19.
Repeats-in-Toxin (RTX) toxin
Play a role in:
– Disrupting the respiratory
mucosa
– Promoting survival of the
bacterium in the bloodstream
– Facilitating invasion of skeletal
system tissues
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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20.
Repeats-in-Toxin (RTX) toxin
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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ResearchGate

21.
The frequent presentation of
K. kingae disease
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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Upper respiratory
infection
Herpetic stomatitis
Hand-foot-and-
mouth disease
Buccal aphthous ulcer
suggesting that viral-induced damage to the
colonized mucosal surface facilitates invasion
of the bloodstream

22.
Clinical presentation
• Septic arthritis is the most common
invasive K. kingae infection in
children
• followed by:
Bacteremia
Osteomyelitis
Endocarditis
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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23.
Clinical presentation (Cont.)
K. Kingae is the most frequent etiology
of skeletal system infections in
children 6 months to 3 yr old in at
least some countries
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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24.
Clinical presentation (Cont.)
• Invasive K. kingae infections is
frequently mild (With the exception
of patients with endocarditis)
-body temperature <38°C
- normal CRP Level
- normal WBC count
Are common
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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25.
Clinical presentation (Cont.)
K. kingae infections requiring
a high index of clinical
suspicion
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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26.
Septic Arthritis
• K. kingae –driven arthritis especially
affects the large, weight-bearing
joints
• involvement of:
-Small metacarpophalangeal
-Sternoclavicular
-Tarsal joints
Is not unusual
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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27.
Septic Arthritis
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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My Health Alberta - Alberta.ca

28.
Septic Arthritis ( Cont.)
• Is an acute presentation
• Involvement of the hip joint
resembles toxic synovitis
• should be always suspected in
children <4 yr old presenting with
hip pain or a limp
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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29.
Septic Arthritis ( Cont.)
Synovial fluid :
• <50,000 WBCs/µL in almost 25%
of the patients,
• The Gram stain is positive in only a
small percentage of cases
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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30.
Septic Arthritis ( Cont.)
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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Digital Commons @ Otterbein - Otterbein University

31.
Osteomyelitis
K. kingae osteomyelitis usually
involves the long bones of the
extremities
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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32.
Osteomyelitis (Cont.)
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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Journal of Clinical Microbiology - American Society for Microbiolo
Knee X-ray analyses
(anteroposterior [a] and lateral
views) demonstrate a round lytic
lesion (arrow) circled by a well-
defined sclerotic margin (dotted
arrow), located in the inferior
metaphysis of the femur,
adjacent to the physis (arrow).
The lateral view also shows a
unilamellar inferoanterior
periosteal reaction (arrowhead).

33.
Osteomyelitis (Cont.)
The calcaneus, talus, sternum,
and clavicle are also frequently
affected
(They are rarely infected by other
bacterial pathogens)
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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34.
Osteomyelitis (Cont.)
• Insidious
• Diagnosed after ≥1 week in
70% of patients.
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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35.
Osteomyelitis (Cont.)
• MRI shows mild bone and soft
tissue changes
• Involvement of the epiphyseal
cartilage appears to be
specifically associated with K.
kingae
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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36.
MRI of acute osteomyelitis
in long bones of children
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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https://www.sciencedirect.com/science/article/pii/S1877056816300998

37.
Osteomyelitis (Cont.)
Chronic osteomyelitis and
functional orthopedic disabilities
are unusual
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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38.
Spondylodiscitis
K. kingae is the 2nd most common
bacterium isolated in children <4
yr old with spondylodiscitis
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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39.
Spondylodiscitis (Cont.)
• Usually Involves the lumbar
intervertebral spaces
• Less frequency:
- thoracolumbar
- thoracic
- lumbosacral
-cervical disks
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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https://www.spineuniverse.com/anatomy/lumbar-spine

40.
Spondylodiscitis (Cont.)
presentation
Limping Refusal to sit or walk
Lumbar pain Neurologic symptoms
Back stiffness Abdominal complaints
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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41.
Spondylodiscitis (Cont.)
MRI studies
demonstrate
narrowing of the
intervertebral
space
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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https://www.researchgate.net/publication/6731419_Kingella_kingae_spondylodiscitis_in_a_child

42.
Spondylodiscitis (Cont.)
• Respond well to appropriate
antibiotic treatment
• recover without complications
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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43.
Occult Bacteremia
Usually : mild to moderate fever,
symptoms suggestive of a viral
upper respiratory infection
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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44.
Occult Bacteremia (Cont.)
-Mean CRP level of 2.2 mg/dL
-Mean WBC count of 12,700/µL.
•Children with K. kingae
bacteremia respond favorably to
a short course of antibiotics
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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45.
Endocarditis
•The disease may affect native
as well as prosthetic valves
•Typically, the left side of the
heart is involved, usually the
mitral valve
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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46.
Endocarditis(Cont.)
•Predisposing factors include :
-cardiac malformations or
-rheumatic valvular disease
•Some patients have previously
normal hearts
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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47.
Endocarditis(Cont.)
Fever and acute-phase reactants
are elevated more in patients with
endocarditis than in those with
uncomplicated bacteremia
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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48.
Echo of an infant with
K. kingae endocarditis
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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Yackov Berkun,et al.Kingella
kingae endocarditis and sepsis in
an infan. European Journal of
Pediatrics volume 163, pages687–
688(2004)

49.
Because of the potential
severity of K. kingae
endocarditis, routine
echocardiographic
evaluation of children
with isolated bacteremia
is indicated
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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50.
Despite the exquisite
susceptibility of K. kingae
to antibiotics,
complications are common
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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51.
Endocarditis: Complications
Cardiac failure
Septic shock
Cerebrovascular accident (stroke)
Other life-threatening
complications
are common
• Mortality rate is high ( >10% )
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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52.
Diagnosis
• Isolation of the bacterium
• Positive nucleic acid amplification
test (NAAT); polymerase chain
reaction PCR)
from a normally sterile site such as
blood, synovial fluid, or bone tissue
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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53.
Diagnosis (Cont.)
K. kingae grows on routine
bacteriologic media BUT its
recovery from exudates is
frequently unsuccessful
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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https://alchetron.com/Kingella-kingae

54.
Diagnosis (Cont.)
Testing bone and joint specimens
by NAAT that targets specific K.
kingae genes results in a 4-fold
improvement in the detection of
the organism
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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55.
Treatment
K. kingae is usually highly susceptible
to penicillin and cephalosporins but
exhibits decreased susceptibility to
oxacillin
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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56.
Treatment (Cont.)
First-line therapy for skeletal
infections in young children :
IV 2nd or 3rd generation
cephalosporin , pending culture
results
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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57.
First-line therapy (Cont.)
For skeletal infections in young
children :
IV 2nd or 3rd generation
cephalosporin , pending culture
results
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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58.
Resistant of K. kingae
To
• Glycopeptide antibiotics (always)
• Clindamycin (majority )
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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59.
Skeletal infections caused by
community-associated methicillin-
resistant S. aureus are common, So
vancomycin or clindamycin are
initially administered
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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60.
Guide switching to oral
antibiotics
1. Favorable clinical response
2. Decreasing CRP levels to
≤20 µg/mL
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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61.
Antibiotic Treatment
duration
Antibiotic treatment for K. kingae
has ranged from:
2-3 wks for arthritis
3-6 wks for osteomyelitis
3-12 wks for spondylodiscitis
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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62.
Most patients respond promptly to
conservative treatment with
appropriate antibiotics and do not
require invasive surgical procedures
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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63.
Antibiotic Treatment K.
kingae
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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64.
Bacteremia without
focal infection
• Initially :an IV β-lactam antibiotic
• Subsequently: an oral drug once the
clinical condition has improved.
• In most cases:
duration of therapy is 1-2 wks
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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65.
Endocarditis
Usually treated with an IV β-
lactam antibiotic alone or in
combination with an
aminoglycoside for 4-7 wks
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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66.
Endocarditis (Cont.)
Early surgical intervention is
necessary for life-threatening
complications unresponsive to
medical therapy
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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67.
Prevention
The risk of asymptomatic
pharyngeal carriers for
developing an invasive K.
kingae infection is low
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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68.
Prevention (Cont.)
If cases occur , SO prophylactic
antibiotic therapy to eradicate
colonization in contacts and
prevent further cases of disease
is indicated .
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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69.
Prophylactic antibiotic
therapy
Either rifampin alone, 10 mg/kg or
20 mg/kg twice daily for 2 days,
Or
rifampin with amoxicillin (80
mg/kg/day) for 2 days or 4 days
25/10/2020Kingella kingae infections Prof. Dr. Saad S Al Ani
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70.
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123FreeVectors

71.
References
• https://www.researchgate.net/publication/233671839_Kingella_kingae_A_Pediatric_Pathogen_of_Increasing_Impo
rtance
• El Houmami N, Minodier P, Dubourg G, et al. An outbreak of Kingella kingae infections associated with hand, foot
and mouth disease/herpangina virus outbreak in Marseille, France, 2013. Pediatr Infect Dis J. 2015;34(3):246–250
• https://en.wikipedia.org/wiki/Kingella_kingae
• https://go.gale.com
• El Houmami N, Mirand A, Dubourg G, et al. Hand, foot and mouth disease and Kingella kingae infections. Pediatr
Infect Dis J. 2015;34(5):547–548
• https://pediatrics.aappublications.org
• https://www.sciencedirect.com/science/article/pii/S1877056816300998
• https://www.spineuniverse.com/anatomy/lumbar-spine
• https://www.researchgate.net/publication/6731419_Kingella_kingae_spondylodiscitis_in_a_child
• Yackov Berkun,et al.Kingella kingae endocarditis and sepsis in an infan. European Journal of
Pediatrics volume 163, pages687–688(2004)
• Yagupsky P, Dubnov-Raz G, Gené A, Ephros M, Israeli-Spanish Kingella kingae Research Group. Differentiating
Kingella kingae septic arthritis of the hip from transient synovitis in young children. J Pediatr . 2014;165:985–989.
• https://alchetron.com/Kingella-kingae
• Dubnov-Raz G, Ephros M, Garty BZ, et al. Invasive pediatric Kingella kingae infections: a nationwide collaborative
study. Pediatr Infect Dis J. 2010;29(7):639–643
• Yagupsky P. Kingella kingae: carriage, transmission, and disease. Clin Microbiol Rev. 2015;28(1):54–79
• http://drugline.org/medic/term/kingella-kingae
• https://www.researchgate.net/publication/233671839_Kingella_kingae_A_Pediatric_Pathogen_of_Increasing_Impo
rtance
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