Case Study
by Thomas Nienaber, MBBS; a,b Holly Maples PhD; a,b Courtney Edgar Zarate, MD a,b
a
UAMS; b Arkansas Children’s Hospital
Salmonella Osteomyelitis in an Immunocompetent
Child: A Question of Penetration
Background
In children, osteomyelitis is usually associated
with hematogenous spread; mean
age 6.6 years old. Unique pediatric treatment
considerations include antimicrobial
pharmacokinetic (PK)/pharmacodynamic
(PD) differences and bone type/development.
Empiric coverage encompasses multiple
pathogens including Staphylococcus aureus,
Streptococcus pyogenes, and Kingella
kingae. One of the most common causes of
osteomyelitis in children with hemoglobinopathies
is Salmonella spp., which is rare
in otherwise healthy children. Generally,
gastrointestinal infections caused by Salmonella
spp are not treated in immunocompetent
children without comorbidities who
are over three months of age. Complications
such as osteomyelitis require antimicrobials
with sufficient bone penetration. We present
the case of a healthy, immunocompetent
10-year-old with salmonella osteomyelitis.
Case
A 10-year-old, 30 kg, female gymnast,
with no significant past medical history,
presents to the emergency department with
two days of progressively worsening right
hip pain, one week of intermittent fever,
and increasing fatigue. The pain worsened
with prolonged weight bearing, but she was
ambulatory. Temperature varied, with maximum
40.9C (105.6F). Two weeks prior to presentation,
she had non-bloody self-resolving
diarrhea. One week later, she presented to a
local hospital. She was diagnosed with influenza
A and prescribed oseltamivir, but due
to side effects this was discontinued. On further
history, her uncle was diagnosed with
Salmonella two weeks prior to presentation,
after a family cookout.
Image 1: MRI image. Arrow indicating area of necrosis in triradiate cartilage.
In the ER, the patient’s temperature was
39.4C (103F); other vitals were stable. Exam
revealed a thin, slightly ill-appearing female
with mild tenderness to palpation in her lower
abdomen and pain with passive and active
flexion and internal rotation of her right
hip, with limited range of motion. CRP was
132. X-rays of her pelvis and right hip were
normal; ultrasound of the hip showed no evidence
of effusion. On hospital day one, MRI
of her right hip showed subtle signs of early
right-hip osteomyelitis of the right-posterior
acetabulum, without evidence of abscess
or effusion. Orthopedics and infectious disease
were consulted. Due to S. aureus being
the most likely cause of osteomyelitis, IV
clindamycin (40 mg/kg/day divided every
eight hours) was started. Orthopedics recommended
no surgical intervention at that
time. She mildly improved, CRP decreased,
but intermittent nightly fevers persisted with
severe pain during the febrile episodes. Daily
blood cultures remained negative. On day
four of admission, due to lack of improvement
and the history of diarrhea and salmonella
exposure, a stool culture was sent. Ceftriaxone
(67 mg/kg/day once daily dosing)
was initiated to cover for salmonella.
On day six, she had been afebrile for 24
hours and CRP had normalized. Stool cultures
grew Salmonella enteritidis, sensitive
to amoxicillin and trimethoprim-sulfamethoxazole.
Despite improvement in inflammatory
markers, she continued to have extreme
pain in her right hip and leg. On day
seven, she was febrile again. Blood cultures
remained negative. MRI of her right hip was
repeated and showed progression of the
osteomyelitis with development of a small
effusion. Decreased enhancement of the
triradiate cartilage was concerning for necrosis,
but no abscess was visible. There was
stable, persistent soft tissue and muscular
edema involving the piriformis muscle that
was seen on previous MRI.
Subsequently, clindamycin was stopped,
daptomycin was added, and a CT-guided
bone biopsy was performed on day 10. This
revealed a lytic lesion between the ilium and
ischium at the level of the triradiate carti-
66 • The Journal of the Arkansas Medical Society www.ArkMed.org