Scalped

You are summoned to the Intensive Care Unit of the University Hospital to consult with the surgical staff on a case of post-surgical infection. The patient is a twenty-six year-old male construction worker treated with reconstructive surgery for an avulsed scalp.

The patient's file states that he received this trauma as a consequence of his shoulder length hair being caught in the gears of a cement mixer. He lost one pint of blood before his arrival at the hospital. His co-workers packed the scalp in ice until they were able to deliver it to the hospital where it was cleaned, shaved, and bathed in a tissue supportive, sterile medium. Teams of microvascular and plastic surgeons were formed to work on re-attaching the scalp.

The surgeons used vein grafts from the patient's superficial forearm veins to reconnect severed arteries and the larger veins. This procedure took eight hours. Blood flow to the area was re-established with the use of heparin locally to provide systemic anti-coagulation. Unfortunately, only several veins were available to drain the scalp, resulting in extreme hematologic congestion of the skin flap. This would eventually result in a cessation of flow due to increased pressure. To combat this problem, surgical leeches were ordered from the hospital pharmacy. The leeches can easily consume the surplus blood, as well as maintain flow through the vessels by the use of their own anti-coagulant produced in their secretions. They were applied four at a time for periods of twelve hours until the flap regained a healthy color and thereby became less cyanotic. The leeches were discontinued on the third day after the accident.

The patient had remained in the ICU until today, his sixth day in the hospital. He is running a low-grade fever, and there is evidence of pus seeping out of the edge of the wound. This appears to be localized to a small site, with some surrounding erythema and inflammation.

Question 1 - Single Best Answer

The pus, erythema and inflammation are indicative of what disease?   

A) tetanus
B) wound infection
C) gangrene
D) toxic shock syndrome
E) hemorrhagic fever

Question 2 - Single Best Answer

What are some bacteria that could cause this?   

A) Staphylococcus and Streptococcus only
B) Pseudomonas and Bordetella
C) Pseudomonas, Staphylococcus, Aeromonas
D) Actinomyces, Treponema, Clostridia
E) Bacteroides, Clostridia, Peptostreptococcus

Question 3 - Single Best Answer

The surgeons do not wish to disturb the flap by debriding the area, fearing that they may lose the whole scalp altogether. You concur with their decision and draw laboratory samples for testing. What samples would you take for testing?   

A) blood
B) urine
C) CSF
D) pus
E) A and D

Question 4 - Single Best Answer

What organisms does this eliminate from your list of possible causes?   

A) Staph and Strep
B) Pseudomonas
C) Clostridia
D) Neisseria
E) all of the above

Question 5 - Single Best Answer

What organism could this be?   

A) Enterococcus
B) Aeromonas
C) Bacteroides
D) Pasturella
E) Campylobacter

Based upon these data you begin intravenous gentamicin. The surgeon decided to place a catheter to drain the accumulated reservoir of pus from the wound, agreeing that the pus poses a greater threat to the wound than mechanical damage from the catheter.

With the use of the antibiotics and a drainage catheter, the inflammation of the wound steadily decreased over a period of thirty-six hours. The offending organism was later identified as Aeromonas hydrophila.

Question 6 - Single Best Answer

What is the likely source of this organism?   

A) the patients hair
B) airborne infection
C) soil and dirt from machinery
D) the leeches
E) surgical equipment

Aeromonas hydrophila is a common freshwater bacteria, and normal flora of freshwater leeches. One of the remaining surgical leeches was volunteered to be used as a sample, and upon plating of its ground up body, produced colonies of A. hydrophila. The risk of infection with this organism is not greater than the danger of a poorly drained wound, so the use of the leeches is justified.

Question 7 - Single Best Answer

What other symptoms can A. hydrophila cause?   

A) brain tumor
B) hemorrhoids
C) diarrhea
D) tetanus
E) toxic shock syndrome