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Fundus lesions from MRSA Bacteremia
Jenny Xu, Resident VA Palo Alto
Abstract: Cotton wool spots are non-specific clinical findings associated with different conditions, with
strong association with diseases such as diabetes and hypertension that affect the microvasculature.
Cotton wool spots may also present in patients with bacteremia and the presence of retinal findings may
indicate the severity of the infection and the mortality of the patient.
I.
Case History
a. Patient demographics: 62 white male
b. Chief compliant: difficulty perceiving details in bright light
c. Ocular history:
i. Diabetes without retinopathy
ii. Mild cataracts
iii. Hyperopia and astigmatism
d. Medical history:
i. History of multiple skin Staph infections with recent hospitalization due to
MRSA perianal abscess that spread to involve the prostate and paraspinal and
epidural abscesses
ii. Diabetes type II for the past 10 years, well controlled; last A1C 6.3%
iii. Hypertension well controlled – currently not on medications, recent BP ranging
from 109/54 to 154/81
iv. Basal cell carcinoma
v. Hyperlipidemia – well controlled, currently not on medications
vi. Coronary heart disease
vii. Recent anemia due to infection
viii. History of substance abuse
a. Medications: IV Vancomycin and ciprofloxacin, insulin, morphine, gapapentin,
II. Pertinent findings
a. Clinical findings:
i. BCVA: 20/30 OU
ii. Refractive error: Pl+1.75x173 OD, -0.50+2.00x004 OS
iii. Pupils: ERRL, -APD
iv. Anterior segment findings: mild cataracts OU, otherwise unremarkable
v. IOP: 12/14mmHg
vi. Posterior segment:
1. ONH: small C/Ds OU, 0.1 OD, 0.2 round with nasal heaping, distinct
margins
2. Posterior pole: multiple peripapillary cotton wool spots OU
3. Macula: flat, even OU
b. Other tests:
i. Zeiss Cirrus optic nerve OCT: RNFL and neuroretinal rim elevation OU likely
from peripapillary cotton wool spots
c. Pertinent laboratories:
i. Positive MRSA Survl Nares DNA
ii. A1C: 6.3%, blood sugar 86 to 200mg/dl
iii. Complete CBC count: normal WBC count with mild anemia
iv. Elevated C-reactive protein and sedimentation rates
v. Negative HIV antibodies
d. Pertinent radiology reports:
i. MRI Lumbar/Spine: Significant dorsal epidural abscess with paraspinal and
psoas abscess
I. Differential Diagnosis
a. Primary/leading: Diabetic and hypertensive retinopathy
b. Others:
i. Anemia
ii. HIV retinopathy
iii. Interferon retinopathy
iv. Purtscher’s traumatic retinal angiography
v. Lymphoma/leukemia
vi. Radiation retinopathy
vii. Multiple myeloma
viii. Auto-immune conditions
ix. Carotid/cardiac emboli
II. Diagnosis and Discussion
a. Retinal lesions from disseminated bacterial infections: Cotton wool spots, superficial
hemes and Roth spots are the most common retinal findings. Various studies report a
percentage of 5% to 15% retinal lesions in patients with bacteremia and septicemia.
Given the well-controlled status of the patient’s diabetes and hypertension, as well as the
lack of other retinal findings, the lesions are unlikely manifestations of diabetes and
hypertension.
b. Pathogenesis: Although the mechanism has not been completely elucidated, there are a
few proposed mechanisms for the occurrence of cotton wool spots in patients with
bacteremia and septecemia. One mechanism proposed was that the build- up of immune
complexes in arteriole walls leading to arteriolar occlusion and therefore formation of the
cotton wool spots. The second mechanism proposes that the sludging of the blood from
the increase of fibrinogen lead to the increased likelihood of ischemic events. The third
mechanism proposes that the direct infection of the blood vessel endothelial walls that
causes blood vessel inflammation, which in turn leads to blood vessel abnormalities and
ischemia. Still another attributes the cause to be the presence of septic emboli, may also
lead to endogenous or metastic endophtalmitis.
III. Treatment, management
a. Treatment: There is no direct treatment of the retinal lesions other than treating the
underlying infection.
b. Bibliography:
i. Rodriguez-Adrian, Libsen J.; King, Robert T.; Tamayo-Derat, Luis G.;
Miller, John W.; Garcia, Charles A.; Rex, John H. Retinal Lesions as
Clues to Disseminated Bacterial and Candidal Infections: Frequency,
Natural History, and Etiology. Medicine. 82(3):187-202, May 2003
ii. Bouza et. Al. A Prospective Search for Ocular Lesions in Hospitalized
Patients with Significant Bacteremia. Clinical Infectious Diseases
3(2):306-12, 2000
iii. Ilhami Celik et al. The Prevalence of Bacteraemia-related retinal lesions in
seriously ill patients. Journal of Infection 52:97-104, 2006
iv. Jaworski, Charles. Morphology of the HIV Versus Diabetic Cotton Wool Spot.
Optometry & Vision Science. 77(11):600-604
IV. Conclusion
a. Clinical Pearls: Bouza et al. noted that ocular lesions attributable to bacteremia were
present in 32% of patient who died compared to 8% in those who survived. Therefore,
although there are no treatments for the retinal manifestations of bacteremia, fundoscopy
may still be helpful as a marker of the severity of bacteremia and prognosis.