Salmonella paratyphi B mycotic aneurysm of the abdominal aorta in

Salmonella paratyphi B mycotic aneurysm of the abdominal aorta in

Le Infezioni in Medicina, n. 2, 174-177, 2015
174 Caso clinico / Case REPORT
Salmonella paratyphi B mycotic
aneurysm of the abdominal aorta in
an HIV-infected patient: a case report
Caso clinico di aneurisma micotico da Salmonella paratyphi B dell’aorta
addominale in un paziente HIV positivo
Nicolò Girometti1, Maddalena Giannella1, Stefano Brocchi2, Lorenzo Badia1,
Leonardo Calza1, Pierluigi Viale1
Department of Medical Sciences and Surgery, Section of Infectious Diseases, University of Bologna,
S. Orsola-Malpighi Hospital, Bologna, Italy;
2
Operative Unit of Radiology, University of Bologna, S. Orsola-Malpighi Hospital, Bologna, Italy
1
A
ortic infection complicated by a mycotic aneurysm is a rare life-threatening event that
progresses rapidly. Traditionally, antibiotic therapy is not sufficient and surgical repair is essential
to prevent aneurysm [1].
Here is reported the story of a 49-year-old man
with a poor control of his multi-resistant HIV
infection diagnosed in 1990 after a short course
of intravenous drug abuse, presented to the local HIV outpatient clinic with non-specific complaints consistent with urinary tract infection.
Seven years prior to admission he was diagnosed
for a Mycobacterium avium complex pancreatic infection with extensive abdominal lymphoadenopathy that required a 6 months treatment course of
rifabutin, ethambuthol, and moxifloxacin.
His last laboratory tests performed 10 days earlier
revealed a CD4 blood-cell count of 107/mm3 accounting for a 4% of total lymphocytes and viral
load of 1089135 copies/mL. The patient was on a
maraviroc + boosted darunavir HAART regimen
because of CCR-5 positivity and a viral history of
multiple virological failures and development of
resistances to all NRTIs, NNRTIs and PIs with the
exception of darunavir. The patient admitted a poor
compliance to the current HAART regimen because
of personal issues during the past 4 months.
Corresponding author
Nicolò Girometti
E-mail: [email protected]
He reported a 7-day history of frequent urine
passing, febrile chills and a dull left lumbar pain.
At time of examination pain radiating to the left
inferior abdomen quadrant, and left groin were
present, abdomen was soft and not tender, while
heart and lungs examination were normal. No
joint pains or skin findings were observed. Mental
status and neurological exam were normal. The
patient was normotensive with a rhythmic pulse
of 102 beats per minute and febrile (37.8°C) and
he was admitted to the hospital with a presumptive diagnosis of urinary tract infection.
Initial laboratory blood tests on that day showed
increased white blood cells count (9760/mm3), a
moderate anaemia (Hb 10.1 g/dL), elevated procalcitonin (0.4 ng/ml) and C-reactive protein (11.4
mg/dL). Transaminases were only slightly elevated and alkaline phosphatase was normal. Urine
analyses were not significant for a urinary tract infection and an abdomen ultrasound was negative
for hydronephrosis, renal stones or other kidney
abnormalities. The patient was empirically started
on piperacillin/tazobactam (13.5g/die) administered by continuous infusion after blood cultures
were performed. 120 minutes later blood cultures
analyzed by matrix-assisted laser, desorption/
ionization-time of flight (MALDI-TOF) mass spectrometry were positive for Salmonella paratyphi B.
After 12 hours the patient was still febrile and
feeling very unwell. An abdominal CT scan was
performed and revealed an aortic aneurysm with
a maximum transversal diameter of 5.1 cm and a
Salmonella paratyphi B mycotic aneurysm of the abdominal aorta in an HIV-infected patient 175
total cranio-caudal length of 9.5 cm starting below the renal ostia and complicated by a posterior
1cm fissuration into a false lumen, which was narrowing the true lumen. Aortic walls were strictly
wrapped by multiple retroperitoneal adenopathies (Figure 1).
The patient was referred for emergency vascular
surgery performed 12 hours later. The aneurysmatic aorta was resected between the area below
the renal arteries and the proximal part of the iliac
arteries and a homograft with a cryopreserved
aorta from donor was performed after a wide
debridement of all infected tissue. The false lumen was filled with purulent material and wall
samples were sent for both histological examination and microbiological culture analysis, which
were positive for Salmonella paratyphi B. The strain
was found to be sensitive to all the routine anti-
Figure 1 - (A) Axial CT projection shows a large fluid
collection with rim enhancement, surrounding the
aorta which presents the saccular dilatation (maximum transversal diameter of 5.1 cm and a total cranio-caudal length of 9.5 cm starting below the renal
ostia) complicated by a posterior fissuration into a
false lumen. (B) A coronal view of the aneurysm (C),
a volume-rendered 3-dimensional reconstruction and
(D) a sagittal view of the mycotic aneurism showing
the multiple colliquated lymph nodes surrounding
the aorta and the saccular aneurysm.
biotics tested for and continuous iv. piperacillin/
tazobactam antibiotic therapy was continued in
combination with antihypertensive agents and
narcotic analgesics. Repeat C reactive protein levels dropped from 31 mg/dL to 9 mg/dL by day 4;
and the patient remained afebrile since post-operative day 1. Unfortunately, despite the improving
clinical condition, the patient died on post-operative day 7 following haemorrhagic shock associated with graft rupture.
nDISCUSSION
Non-typhoid Salmonella species (NTS), including Salmonella paratyphi B, consist of a vast group
of anaerobic, rod-shaped Gram negative bacteria,
responsible for a large number of widely distributed foodborne diseases [2]. Salmonella paratyphi B
infection causes paratyphoid fever, a disease characterized by acute onset of fever, abdominal pain,
diarrhoea, nausea and sometimes vomit [2, 3].
However, 5% of patients also develop bacteraemia
after the bacterial translocation over the gastrointestinal tract [4]. Some Salmonella serotypes show
a predisposition to develop bacteraemia over others, and is much more frequent in the elderly population and in immunocompromised patients, including HIV-infected patients [1, 4]. Limited data
suggest 30-day mortality rates as high as 60% in
developing countries [5]. NTS can be responsible
for as much as 8% of bacteraemia in HIV patients
and are found in 15-35% of bacterial aortitis [1,
6-8]. NTS sepsis is more severe in HIV-positive patients with mortality related to severe sepsis in this
group ranging around 30-55% [9, 10].
NTS may have predilection to attack the damaged
vascular endothelium, favouring the development
of a mycotic aneurysm [7]. The infra-renal segment of the abdominal aorta is the most frequent
location for infected aneurysms, which can be
evaluated by contrast-enhanced CT (CECT) that
reveals aortic wall thickening, periaortic fluid or
soft-tissue accumulation and rapidly progressing
saccular aneurysms [1, 8, 11-14]. CECT also allows
a multiplanar view with 3-dimensional reconstructions and excellent spatial resolutions, evaluating
the aortic wall changes, luminal changes and disease extent to help find the best surgical approach
[15]. Our patient was diagnosed with an advanced
infectious aortitis complicated by an initial fissura-
176 N. Girometti, et al.
tion of a mycotic aneurysm (see Figure 1), consistent with risk factors reported in the literature [16].
Infected aneurysms are usually irreversible and
appear very frequently as complication of aortitis, holding a 40-45% mortality rate even when
treated with both antibiotic therapy and surgery,
although it has been demonstrated a beneficial
impact on survival when prompt diagnosis and
treatment are provided [1, 17, 18]. While an initial
medical approach with adequate antibiotic therapy alone is reported to perform poorly with an
average 96% mortality, early open surgery seems
to grant the best outcome, albeit post-operatory
mortality ranges from 11% to 45% depending on
the extent of vascular damage, surgical technique,
and time to treat [1, 8, 17, 19, 20]. Open-surgery
treatment may not be suitable in patients with
high operative risk and repair of thoracic aortic
aneurysms by endoluminal stent-grafting is an
emerging alternative to surgical intervention,
including treatment of mycotic aneurysm [8, 18,
21]. For those patients with non-critical conditions, length of antimicrobial treatment before
surgery is controversial and ranges from 1 week
to 4 months [20]. Microbiological management of
intraoperatory samples is also a very important
stage of management, because pathologic confirmation of the diagnosis and susceptibility testing
are essential to confirm adequate antimicrobial
therapy.
Despite the unfortunate ending, our case report
underlines the importance to include cardiovascular infections in the differential diagnosis every
time a septic patient with an uncontrolled HIV
viral load and a lymphocyte CD4+ cell-count below 200/mm3. In these situations, Salmonella species infection can be a possible cause for disease
and aorta must be investigated along other sites.
MALDI-TOF can be a very useful resource, offering the fastest way to detect the pathogen from
blood cultures and prompting appropriate follow-up radiographic examinations [22].
No financial support was received for this study
All authors: No reported conflicts of interest.
Keywords: HIV, Salmonella paratyphi, aortic aneurysm.
SummaRY
An HIV-infected 49-year-old man was admitted with
polyuria, fever, chills and a dull left lumbar pain.
Laboratory tests showed increased C-reactive protein while urine analysis and abdomen ultrasound
scan were negative. Blood cultures revealed a Salmonella paratyphi B, identified through MALDI-TOF
mass spectrometry. Targeted antibiotic therapy with
intravenous piperacillin/tazobactam was started and
a multi-phase contrast-enhanced abdomen CT-scan
was performed at 24 hours from admission showing a
saccular aneurysm of the abdominal aorta with a 1 cm
penetrating aortic ulcer on posterior wall. The patient
underwent emergency vascular surgery at 34 hours
from admission for debridement and homo-graft
placement of sub-renal aorta, and surgical samples
were sent for microbiological analysis. Unfortunately,
the patient died on post-surgical day 7 after haemorrhagic shock due to laceration of his graft. Salmonella paratyphi infection can be responsible for sepsis
in severely immunosuppressed patients with poorly
controlled HIV, requiring careful work-up for cardiovascular involvement.
RIASSUNTO
Di seguito descriviamo il caso di un paziente HIV-positivo di 49
anni, con uno scarso controllo della malattia di base, che si presenta con febbre, poliuria e dolore lombare. In seguito alle prime
indagini diagnostiche si riscontra un quadro settico per cui si
imposta terapia antibiotica empirica con piperacillina/tazobactam e.v. che viene successivamente confermata alla luce della
identificazione MALDI-TOF su emocolture di Salmonella paratyphi. Per il persistere di dolore addominale il paziente veniva
sottoposto a TC addome multifase che identificava la presenza di
aneurisma dell’aorta addominale con iniziale ulcerazione della
parete vascolare posteriore. Pertanto, a 34 ore dal ricovero, veniva sottoposto ad intervento di resezione dell’aneurisma a livello
sotto-renale e trapianto aortico da donatore. Nel post-intervento
si assisteva al netto miglioramento degli indici di flogosi e allo
sfebbramento del paziente, che decedeva però in settima giornata post-operatoria in seguito a shock emorragico da rottura del
graft. L’infezione da Salmonella paratyphi può provocare sepsi in pazienti gravemente immunocompromessi e con malattia
da HIV scarsamente controllata, e richiede un controllo completo minuzioso per il coinvolgimento cardiovascolare.
Salmonella paratyphi B mycotic aneurysm of the abdominal aorta in an HIV-infected patient 177
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