QUESTION: 73

A 53-year-old fisherman develops pain and swelling of the right hand 8 hours after suffering a fish hook injury to the finger. On physical examination, the patient's temperature is 102.8°F and the patient ap pears septic. The patient's hand and a Gram stain of material aspirated from a bulla are shown in Figures below.

What is the most likely etiology of this bacteremia?

Staphylococcus aureus cellulitis
group A, beta-hemolytic Streptococcus sepsis
Pasteurella multocida cellulitis
Vibrio vulnificus sepsis
Eikenella corrodens cellulitis

Answer(s): D

Explanation:

V. vulnificus is associated with sepsis in patients with liver disease who eat raw oysters or those with salt water contamination of wounds, like those caused by fish hooks. P. multocida is a cause of cellulitis caused by exposure to cat saliva as a result of a bite or a clawing injury. E. corrodens is associated with cellulitis caused by a human bite. Staphylococcus and Streptococcus are the most common causes of cellulitis. The Gram stain shows gram-negative, commashaped organisms typical for vibrios. Close attention should be paid to the wound site in the setting of a V. vulnificus infection. The wound site must be thoroughly cleaned and any necrotic tissue debrided. If necessary, fasciotomy or limb amputation should be performed. Antibiotic therapy should begin immediately as well. Use of a combination of doxycycline and a thirdgeneration cephalosporin such as ceftazidime is considered first-line. Quinolones may be considered as alternative therapy in the case of drug allergy or contraindication. A combination regimen using TMP-SMZ and an aminoglycoside is indicated for treatment in children since doxycycline and quinolones are contraindicated.

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QUESTION: 74

A 53-year-old fisherman develops pain and swelling of the right hand 8 hours after suffering a fish hook injury to the finger. On physical examination, the patient's temperature is 102.8°F and the patient ap pears septic. The patient's hand and a Gram stain of material aspirated from a bulla are shown in Figures below.

After appropriate wound care and debridement of necrotic tissue as necessary, which antibiotics should be started in this patient?

levofloxacin
vancomycin
doxycycline and ceftazidime
nafcillin and gentamicin
trimethoprim-sulfamethoxazole(TMP-SMZ)

Answer(s): C

Explanation:

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QUESTION: 75

You receive a call from the nurse at a nursing home for a 70-year-old patient of yours who was febrile overnight and had blood cultures, CXR, and urinalysis ordered by the housestaff. The patient was started empirically on a fluoroquinolone orally. The nurse informs you that the CXR and urinalysis were normal but the blood culture grew out Enterococcus faecalis. The patient has been on oral fluoroquinolone for 36 hours and patient is still febrile but appears stable. Which of the following is most appropriate?

Continue the oral quinolone and add an intravenous first-generation cephalosporin.
Discontinue the oral quinolone and start treatment with an intravenous secondgeneration cephalosporin.
Discontinue the quinolone and start treatment with an intravenous thirdgeneration cephalosporin.
Discontinue the quinolone and start treatment with intravenous ampicillin and an aminoglycoside.
Continue the quinolone, but change from oral to IV route of administration.

Answer(s): D

Explanation:

No cephalosporin is appropriate for the treatment of E. faecalis. This organism is occasionally sensitive to fluoroquinolones, but this choice is unreliable. The combination of ampicillin and an aminoglycoside is synergistic for susceptible E

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QUESTION: 76

A30-year-old female presents to your office for the evaluation of a rash on her back. It has been present and growing for about a week. Along with this rash, she has had a fever, headache, myalgias, and fatigue. Her symptoms started about a week after returning from a camping trip to New England. She denies having any bites from ticks or other insects and exposure to poison ivy and has had no wounds to her skin. On examination, her temperature is 99.5°F and her v ital signs are otherwise normal. Her rash is shown in Figure. Her examination is otherwise unremarkable.

What is the most likely cause of her rash?

contact dermatitis secondary to plant exposure
infection transmitted by tick bite
infection transmitted by mosquito bite
group A Streptococcus suprainfection of small puncture wound
allergic reaction to ingested (i.e., food) allergen

Answer(s): B

Explanation:

Lyme disease is the most common vector-borne disease in the United States. It is caused by infection with B. burgdorferi, a spirochete that is transmitted to humans through the bite of ticks of the Ixodes family. These ticks are very small, so frequently the victim is unaware of having been bitten. After an incubation of 330 days, a red macule or papule develops at the site of the bite, which expands to form a large annular lesion with partial central clearing or several red rings within an outside ring. The lesion, erythema migrans, is often said to resemble a "bull's-eye" target. Within a few days or weeks of this, the patient often complains of flu-like symptoms fever, chills, myalgias, headache, fatigue caused by the hematogenous spread of the spirochete. Lyme disease has been found in most of the United States, but is most common in the New England states, where over 20% of Ixodes ticks are infected with the spirochete. Left untreated, patients may progress to develop multiple complications, including neurologic, musculoskeletal, or cardiac involvement. Lyme disease is usually diagnosed by recognition of the symptoms and signs, along with serologic testing. However, serologic tests may be negative for several weeks after infection. IgG and IgM should be tested in acute and convalescent samples. Only 2030% of exposures will have positive acute antibody responses, whereas 7080% will have positive convalescent titers. Samples that are positive by ELISA assay should be confirmed by Western blot testing. Empirical antibiotic therapy, preferably with doxycycline, is recommended for patients with a high probability of Lyme disease--such as those with erythema migrans. Doxycycline is the preferred antibiotic for treatment of early stage Lyme disease in adults because of its effectiveness against Lyme disease and other infections, such as human granulocytic ehrlichiosis, which is also transmitted by Ixodes ticks. Waiting to treat until convalescent titers become positive would not be recommended in this patient, who has a high likelihood of having Lyme disease, as it may result in more complications developing and the need for longer and more intensive treatment. For more advanced stages of disease, such as the presence of nervous system involvement or third-degree heart block, parenteral antibiotic treatment is necessary. Ceftriaxone is the treatment of choice in this setting.

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