Discussion
To our knowledge, this is the first reported case of multiple PLA caused
by Y. pseudotuberculosis in Denmark. Our patient presented with
six weeks of intermittently fever, fatigue, and unattended weight loss.
A CT-scan performed in the General Practitioner setting had revealed the
diagnosis of multiple hepatic abscesses. She was successfully treated
with percutaneous drainage combined with antibiotic therapy with
piperacillin/tazobactam and ciprofloxacin for a total of eight weeks.
In general, approximately half of PLA patients have secondary
bacteremia.8 While there are only a few case-reports
of Y. pseudotuberculosis PLA,9-14 it seems this
also applies to Y. pseudotuberculosis PLA (in four cases the
bacteria was cultured from blood).9-11,13 In one case,
the diagnosis was based on antibody titers for Y.
pseudotuberculosis only.12 In our case, blood culture
and stool were culture negative, but only the first blood culture set
was taken prior to antibiotic therapy. Overall, cryptogenic liver
abscesses are most often monomicrobial.8 Prior
case-reports of Y. pseudotuberculosis PLA9-14and ours, suggest that Y. pseudotuberculosis PLA are also
monomicrobial.
The majority of PLA occurs in patients with underlying hepatobiliary or
pancreatic disease through ascending cholangitis or hematogenous spread
though the portal vein,8 others may be induced by
trauma (e.g., post-surgical), and a substantial part remains
cryptogenic. While our patient had choledocholithiasis, she had no signs
of cholecystitis or cholestasis. Diabetes mellitus is associated with an
increased risk of PLA,18 and also a risk factor for
systemic Y. pseudotuberculosis infection, including
bacteremia.2 Our patient had a newly diagnosis of type
2 diabetes mellitus, which also was reported in three of six prior cases
of Y. pseudotuberculosis PLA,9,11,13 and in a
patient with a splenic abscess.13 Iron overload has
been suggested to predispose for Y. enterocolitica liver
abscesses and systemic Y. pseudotuberculosis infection (owing to
lack of sophisticated iron metabolism pathways).19 One
of six prior cases of Y. pseudotuberculosis PLA had a diagnosis
of genetic hemochromatosis.10 While our patient had a
slightly elevated level of plasma ferritin at admission, this was
interpreted as an acute-phase reactant, as she had no other signs of
hemochromatosis.
Y. pseudotuberculosis is hosted by various animals with main
reservoir in rodents, deer and wild birds.2Multiple Y.
pseudotuberculosis outbreaks has been reported from contaminated food
such as carrots and lettuce,20,21 but no Danish
outbreaks have yet been identified. We were not able to confirm the
source of infection in our patient, and she had no close contacts to
animals.
Treatment of PLA includes drainage (either percutaneous or surgical),
and antibiotic therapy. The usual regime includes two weeks of parental
antibiotic treatment followed by four to six weeks of oral
antibiotics.5 The optimal antibiotic treatment and
duration of antimicrobial treatment for Y. pseudotuberculosis PLA
is unknown, and was heterogeneously reported in the published
cases.9-14 Y. pseudotuberculosis is usually in
vitro susceptible to ampicillin, cephalosporins, tetracycline,
ciprofloxacin and aminoglycosides,1,2 and the
recommended antibiotic therapy in case of bacteraemia or systemic
infection includes a third-generation cephalosporin such as ceftriaxone
2g per day (or alternatively ciprofloxacin) combined with a daily dose
of gentamycin 5mg/kg.2,22,23 The treatment regimens of
the prior cases of Y. pseudotuberculosis PLA all differed, but
included ampicillin, amoxicillin-clavulanic acid, ceftriaxone,
quinolones (ciprofloxacin and ofloxacin), gentamicin, and in one case
troleandomycin.9-14
Our isolate of Y. pseudotuberculosis was susceptible for all
tested antibiotics including ampicillin, but owing to worsening on the
clinical condition after drainage, the empiric piperacillin-tazobactam
treatment was supplemented with ciprofloxacin. After ribosomal 16S PCR
analysis confirmed monomicrobial finding of Y.
pseudotuberculosis , oral treatment was finalized with ciprofloxacin
alone.
In conclusion, this is the first Danish case of Y.
pseudotuberculosis PLA. Y. pseudotuberculosis was identified in
pus after liver abscess drainage but not in blood cultures, highlighting
the need for drainage for both treatment and for identification of the
aetiology. Of note, our patient had diabetes mellitus, which was also
reported in prior cases of Y. pseudotuberculosis PLA.