A community-acquired methicillin-resistant Staphylococcus aureus liver abscess.
ABSTRACT Liver abscesses caused by community-acquired methicillin-resistant Staphylococcus aureus are rarely reported. We report such a case in a 25-year-old man who presented with an intermittent fever. He had a history of prolonged antibiotic use for acne and skin abscesses. The liver abscess was successfully treated with percutaneous drainage and a prolonged course of linezolid. To our knowledge, this is the first reported case of a community-acquired methicillin-resistant Staphylococcus aureus liver abscess in Hong Kong, demonstrating the increasing threat posed by this multidrug-resistant organism. This case also suggests that a different epidemiology and route of infection may apply to community-acquired methicillin-resistant Staphylococcus aureus liver abscesses in contrast to the more common pyogenic liver abscesses.
A pyogenic liver abscess is a major hepatobiliary infection that carries significant morbidity
and mortality. The dominant aetiology has changed over the years, from suppurative
appendicitis during the era before antibiotic usage to different hepatobiliary and colonic
pathologies in recent years. These abscesses are usually polymicrobial, with Escherichia
coli, Klebsiella species and Bacteroides the most common pathogens. Most can be
successfully treated with antibiotics selected after the pathogens and their respective
sensitivities have been determined by culturing materials drained percutaneously from
the abscess. Surgical drainage may be required if this fails.
pyogenic liver abscesses1), with the methicillin-resistant strain appearing in even fewer
cases. In those cases, the bacteria are predominantly hospital-acquired, but the number
of community-acquired strains is rising. Because community-acquired methicillin-
resistant Staphylococcus aureus (MRSA) was first found in skin and soft tissue infections,
communities worldwide are concerned about its susceptibility to a narrow spectrum of
antibiotics, and fear the development of an antibiotic-resistant ‘superbug’. In Hong Kong,
any infection caused by this bacterial species must be reported and the public is being
educated about the need to use antibiotics sparingly. Skin and soft tissue remain the
major routes of infection, but involvement of other sites can be serious, even fatal.2,3 Such
infections may affect the healthy population as well. In this report, we present a case of
community-acquired MRSA liver abscess in a young, fit man.
Staphylococcus aureus is an uncommon cause of liver abscess (<10% of all
A 25-year-old man with good past health was admitted in February 2009 with a 10-day history
of intermittent fever associated with sweating. He had used antibiotics within 6 months of
the admission, including self-prescription of clarithromycin for 2 months to treat acne, and a
1-week course of amoxicillin/clavulanate for a left thigh abscess. No specimens were cultured
before these infections were treated. A physical examination found that his abdomen was
soft with no palpable masses. Blood tests revealed an elevated alkaline phosphatase level
of 194 IU/L associated with neutrophilic leukocytosis (17.7 x 109 /L, neutrophils 83%), an
elevated C-reactive protein level (301.1 mg/L), and an elevated erythrocyte sedimentation
rate (115 mm/h). Blood cultures were negative. Ultrasound showed a multi-loculated liver
abscess in segment 6 measuring 7.6 x 5.1 x 5.5 cm (Fig 1). He was managed with percutaneous
drainage, which yielded 5 mL of thick brownish pus. Computed tomography showed a
residual abscess at segment 6 of liver around 1 week afterwards (Fig 2).
pus. The pus was cultured and grew MRSA. Genotyping confirmed that the strain was
community-acquired (Staphylococcal cassette chromosome mec type V; Panton-Valentine
Leucocidin gene positive). Blood, urine, and throat swabs were cultured but were negative
for MRSA. Magnetic resonance cholangiopancreatography and a barium enema showed no
He was managed with percutaneous drainage, which yielded 5 mL of thick brownish
A community-acquired methicillin-resistant
Staphylococcus aureus liver abscess
Liver abscess; Methicillin resistance;
Staphylococcus aureus; Vancomycin
Hong Kong Med J 2010;16:227-9
Division of Hepatobiliary and Pancreatic
Surgery, Department of Surgery, The
Chinese University of Hong Kong, Prince
of Wales Hospital, Shatin, Hong Kong
VWY Wong, MRCS(Ed)
YS Cheung, FRCSEd (Gen)
J Wong, FRCSEd (Gen)
KF Lee, FRCSEd (Gen)
PBS Lai, MD, FRCSEd (Gen)
Correspondence to: Prof PBS Lai
Vivien WY Wong
Paul BS Lai
Liver abscesses caused by community-acquired methicillin-resistant Staphylococcus aureus
are rarely reported. We report such a case in a 25-year-old man who presented with an
intermittent fever. He had a history of prolonged antibiotic use for acne and skin abscesses.
The liver abscess was successfully treated with percutaneous drainage and a prolonged
course of linezolid. To our knowledge, this is the first reported case of a community-acquired
methicillin-resistant Staphylococcus aureus liver abscess in Hong Kong, demonstrating the
increasing threat posed by this multidrug-resistant organism. This case also suggests that a
different epidemiology and route of infection may apply to community-acquired methicillin-
resistant Staphylococcus aureus liver abscesses in contrast to the more common pyogenic
evidence of hepatobiliary or colonic pathology. He had
no evidence of the human immunodeficiency virus.
but continued to have low-grade fever and after
The patient was commenced on vancomycin
2 weeks of treatment his C-reactive protein was
elevated, despite the achievement and maintenance
of a therapeutic serum concentration of the drug.
His condition improved after the vancomycin was
replaced with linezolid, so he was discharged with a
6-week course of oral linezolid. Follow-up computed
tomography performed 2 months after the initial
percutaneous drainage showed resolution of the
Staphylococcus aureus is commonly found on
human skin and mucosae. Around one third of the
healthy population carries the bacteria in their nasal
cavity or skin with no evidence of infection. On the
other hand, this bacterium can cause skin infections,
wound infections, food poisoning, pneumonia, and
bacteraemia. Beta-lactam antibiotics are generally
effective for managing methicillin-sensitive S aureus
infections. The appearance of the methicillin-
resistant strains is attracting attention as they are
resistant to traditional anti-staphylococcal beta-
lactam antibiotics, and the use of effective antibiotics,
such as vancomycin, may cause nephrotoxicity. The
emergence of MRSA has also alerted clinicians to
the possibility that further resistance to these potent
antibiotics may develop. Vancomycin-intermediate
or -resistant S aureus has been isolated in various
countries including Japan since 1996.4 It has been
proposed that the mechanism of this resistance is
production and accumulation of excessive amounts
of cell-wall peptidoglycan.5
infections are more common than the community-
acquired strain. Community-acquired MRSA infection
was first reported in Hong Kong in 2004.6 Its incidence,
however, has increased since it became a statutory
notifiable disease in January 2007.7 Infections most
commonly involve skin or soft tissue (99%), of which
around 30% involve the lower limbs, followed by the
buttocks, groin, and perineum.8 Infections involving
other organs are rare but can be fatal.9 Previously
notified cases include lower respiratory tract
infections and meningitis. To our knowledge, the
case we report here is the first report of a liver abscess
caused by this type of bacteria in Hong Kong.
In Hong Kong, hospital-acquired MRSA
polymicrobial. Staphylococcus aureus has been a
reported pathogen in less than 10% of all hepatic
abscesses.1 Twenty case reports described liver
abscesses caused by MRSA, and only three of these
described the community-acquired strain.10-12
Pyogenic liver abscesses are usually
from community-acquired MRSA liver abscesses.
One of the three reports in the literature described
such an infection in a young, fit patient. The report
suggested that community-acquired MRSA liver
Healthy people do not seem to be protected
FIG 1. Ultrasound image showing a 7.6 x 5.1 x 5.5 cm
heterogeneous mass lesion in segment 6/7 of the liver, with a
partly liquefied component
FIG 2. Computed tomographic image showing a rim-enhancing
lesion suggestive of residual liver abscess after drainage and
abscesses may have a severe clinical course, requiring
surgical management, and that such aggressive liver
abscesses may be secondary to skin and soft tissue
infections.12 In our case, the patient also had a history
of skin infections treated with prolonged antibiotic
courses. Nevertheless, his clinical course was not
so severe; percutaneous drainage and antibiotics
achieved an effective resolution.
than vancomycin. Reports have shown that linezolid
has a similar clinical or microbiological cure rate
to vancomycin for MRSA infections involving skin,
soft tissue, and other organ infections and also has
similar adverse effect rates.13,14 It is well tolerated by
those in whom vancomycin is nephrotoxic or who
lack intravenous access.15,16 It can be administered
intravenously or orally, allowing a more flexible
treatment plan. Moreover, the development of new-
onset resistance and cross-resistance is thought to be
less likely with linezolid, due to its ability to inhibit
protein synthesis early by binding to ribosomal
subunits. This is a unique mechanism of action not
seen in any other currently available antimicrobial
agents.17 Nevertheless, attention should be paid to
the possible development of peripheral neuropathy,
toxic optical neuropathy, myelosuppression, and
In our patients, linezolid was more effective
system.? In:? Mandell? GL,? Bennett? JE,? Dolin? R.? Principles?
and? practice? of? infectious? disease.? 6th? ed.? Philadelphia:?
resistant? Staphylococcus aureus? carrying? the? Panton-
hospitals? of? strains? of? Staphylococcus aureus? heterogeneously?
5.? Hiramatsu? K.? Vancomycin-resistant Staphylococcus aureus:? a?
7.? Number? of? notifications? for? notifiable? infectious? disease.?
8.? Update? of? epidemiology?
methicillin? resistant? Staphylococcal aureus? (CA-MRSA)?
infection? in? Hong? Kong.? Centre? for? Health? Protection?
9.? A? review? of? community-associated? methicillin? resistant?
10.?Mancao? M,? Estrada? B,? Wilson? F,? Figarola? M,? Wesenberg? R.?
11.?Chi? CY,? Kuo? BI,? Fung? CP,? Liu? CY.? Community-acquired?
methicillin-resistant? Staphylococcus aureus? liver? abscess?
B.? Linezolid? versus? vancomycin? for? the? treatment? of?
methicillin-resistant?Staphylococcus aureus infections.?Clin?
15.?Moise? PA,? Forrest? A,? Birmingham? MC,? Schentag? JJ.?
The? efficacy? and? safety? of? linezolid? as? treatment? for
Staphylococcus aureus? infections? in? compassionate? use?
hyperlactataemia. Neuropathies have been reported
after prolonged linezolid therapy (>28 days), and
myelosuppression may occur as pancytopenia, or
more commonly as isolated cytopenia, after 14 days
of therapy.18 Most of these side-effects subside upon
discontinuation of linezolid, but recovery from
peripheral neuropathy is incomplete, with residual
paraesthesia in the distal extremities.18
This case illustrates how community-acquired MRSA
is posing an increasing threat to our population. Even
young, fit patients may be affected, and previous skin
infection managed with prolonged antibiotic use
seems to be a predisposing factor. Liver abscesses
caused by community-acquired MRSA may follow
a spectrum of clinical courses. Our patient had
a relatively mild clinical course; his abscess was
effectively managed with percutaneous drainage
and a prolonged course of appropriate antibiotics.
Nevertheless there have been reports of virulent
disease requiring surgical intervention. Infection of
MRSA should be suspected if a liver abscess does not
respond to the usual antibiotic regimen. In confirmed
cases, linezolid may be a suitable alternative if
vancomycin is not tolerated or becomes ineffective.