Baylor University Medical Center Proceedings April 2014, Volume 27, Number 2 | Page 66

Table 2. Renal function tests over time
Day 4 Day 14 Day 44 Day 55 Day 79
Blood urea nitrogen (mg/dL)

96

129

50

52

28

Creatinine (mg/dL)

8.0

10.5

5.4

5.3

2.1

cultures, approximately a month following admission, were
confirmed as Capnocytophaga canimorsus (DF-2).
Hemodialysis was initiated on day 4. The patient remained
virtually anuric. Residual renal function by creatinine clearance
was zero. He underwent dialysis 4 times per week. He was extremely catabolic, with a urea nitrogen generation rate of 20 g
per day. He was treated with oral and parenteral nutrition to
achieve a protein intake of 120 g per day (1.8 g/kg per day). He
was extubated on day 6. His blood pressure was stable off dopamine at that time. Antibiotics were continued for 2 weeks.
A mercaptoacetyltriglycine (MAG3) scan on day 20 revealed
clear evidence of radionuclide uptake without renal excretion,
suggesting reversible renal disease. Hemodialysis was decreased to
3 times per week. He underwent amputation of all 10 toes on day
24, with split-thickness skin grafting to both arms and legs at the
same time. He underwent repeat skin grafting 1 week later.
Residual renal function measured by creatinine clearance
was 2 mL/min on day 31. At that time, his urine output was
rising. He underwent his last hemodialysis treatment on day
40 after 21 treatments. Residual renal function measured by
creatinine clearance on day 44 was 7 mL/min. The patient was
subsequently discharged on day 48. He experienced continued
improvement in his renal function in the outpatient setting over
the next month (Table 2). Dialysis was never again needed.
DISCUSSION
Capnocytophaga canimorsus (formerly CDC Group DF-2) has
been rarely but regularly isolated from dog or cat bite infections
since its discovery in 1976. It is a commensal organism of the
canine oral flora and can be isolated from mouths of healthy dogs
and cats (2, 3). Zoonotic infectious manifestations range from local
cellulitis to fulminant gram-negative sepsis with multiorgan failure,
disseminated intravascular coagulation, and peripheral gangrene.
The portal of entry is usually the skin after having been bitten by
a dog or cat, but there have also been reports of infection from
ordinary exposure, licks, and scratches (3–7). The organism spreads
hematogenously to the meninges, endocardium, and synovium,
causing infection in those sites. The reported mortality rate is 30%
to 36%, and implicated risk factors are a history of splenectomy,
alcohol abuse, lung disease, and an immunocompromised state.
Infection, however, is not limited to that population, with as many
as 40% of cases having no obvious risk factor (2, 4, 5).
Association of a generalized Shwartzman reaction after a dog
bite was first reported in 1970, when Capnocytophaga canimorsus
was still unrecognized as a significant pathogen in dog bites. The
generalized Shwartzman reaction has been well described in fulminant gram-negative septicemia in pregnancy and meningococcemia. It is characterized by thrombohemorrhagic skin necrosis and
140

disseminated intravascular coagulation from endotoxins causing
deposition of fibrin thrombi in small vessels (mainly renal glomerular capillaries and adrenals), which is considered the hallmark
of the disease. The deposition of fibrin thrombi usually results in
varying degrees o f necrosis and hemorrhage, which accounts for the
renal failure from bilateral renal cortical necrosis and peripheral gangrene associated with the generalized Shwartzman reaction (8, 9).
Subsequent case reports of Capnocytophaga canimorsus infections,
including our case, made it clear, however, that infection with the
organism can be associated with renal failure apart from or as part
of the full spectrum of the generalized Shwartzman reaction (4–6,
10, 11). For this reason, we would like to coin the term DF-2
nephropathy to describe reversible or nonreversible oligoanuric
renal failure in Capnocytophaga canimorsus (DF-2) sepsis with or
without association with a generalized Shwartzman reaction.
Capnocytophaga canimorsus is susceptible to penicillins, imipenem, erythromycin, vancomycin, clindamycin, third-generation
cephalosporins, chloramphenicol, rifampicin, doxycycline, and
fluoroquinolones. It is resistant to aztreonam and aminoglycosides
and has variable resistance to trimethoprim-sulfamethoxazole. As
such, penicillin had long been the initial empiric drug of choice. A
recent report of a beta-lactamase–resistant strain has made a thirdgeneration cephalosporin or combination beta-lactam antibiotic/
beta-lactamase inhibitor better empiric coverage. The organism
can be identified by conventional microbiologic identification,
polymerase chain reaction, or DNA sequencing (1, 7, 12, 13).
1.

2.

3.
4.

5.

6.
7.
8.

9.
10.

11.
12.

13.

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Findling JW, Pohlmann GP, Rose HD. Fulminant gram-negative bacillemia (DF-2) following a dog bite in an asplenic woman. Am J Med
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