NMS Q&A Family Medicine

192 NMS Q&A Family MedicineExamination Answers1. The answer is C A. israelii . The clinical presentationdepicted is typical for actinomycosis with its slow andinsidious course, characterized by granulomatous spreadand fistula formation. It is best known as the cause of“lumpy jaw” but can involve the intestines, and in thepresent case, pelvic inflammatory disease, known, especiallywhen an IUD has been left in too long. The papsmear virtually rules out cancer in a process so faradvanced as that in the vignette. Clinically none of thebacterial infections match the case, nor does histoplasmosisfollows the pathologic course shown here.2. The answer is B Cholera. Cholera sets on suddenly,results in watery gray stools (rice water stools) and massivefluid loss. There is no fever, blood, nor severe cramps.The fluid loss in full-blown cases is massive, up to 15 L/day and sometimes 1 L/hour, and is the cause of death iffluid therapy is not aggressively pursued. Toxigenic E. coliand shigellosis are both forms of dysentery (bloody diarrhea).Typhoid fever causes acute systemic illness withhigh fevers. Travelers diarrhea generally causes severecramps as well as diarrhea for a brief period but not themassive amounts of fluid loss. While stool cultures willreveal Vibrio cholerae , confirming the diagnosis, the diseaseis caused by the toxin adenylyl cyclase elaboratedthereby. The disease is treated by aggressive fluid replacement(addressing physiological amounts of saline), andthe course can be shortened by tetracycline, ampicillin,chloramphenicol, or azithromycin.3. The answer is B. GBS is the most common infection ofneonates. It occurs usually quite early after delivery in theform of pneumonia but may be expressed in more subtleclinical form as in this case, with hypotonia and poorfeeding. Risk factors include prematurity, delayed deliveryafter membrane rupture, and GBS infection in themother. However, infection may occur as late as at 2 weeks.In the latter case, GBS often presents as meningitis. Eachof the other organisms, among the choices, may be foundin the newborn as well.4. The answer is B. Botulism is found in essentially threeforms: the foodborne form, as in the ingestion of preformedtoxin in canned, smoked, or vacuum-packed foods,which is potentially the most acute and deadly form; infantbotulism, which occurs when the ingestion of botulinumspores (usually in honey) causes botulinum toxin to beproduced in the gastrointestinal tract of infants, andwound borne botulism. The latter is found most often ininjection drug users, probably most likely in those cases inwhich the addict has run out of functional surface veinsand resorted to what is known as skin popping. The symptomsare those of anticholinergic poisoning, and there is acurare-like effect on the skeletal muscles (i.e., flaccidparalysis in the advanced case). Dyspnea is due to paralysisof the diaphragm and intercostal muscles. Tetanus isnot characterized by anticholinergic symptoms, and muscletone is heightened, not reduced. Myasthenia gravisand Guillain–Barré syndrome should be considered, butnot in the context of intravenous drug abuse.5. The answer is E. Surgical exploration, probable debridement,and biopsy are crucial in the clinical pictureshown. Narcotizing soft tissue infection, appreciatedincreasingly in the past 10 years, usually begins acutely,although on occasion over a more prolonged period.Originally thought to be caused by an evolved virulentstrain of beta-hemolytic group A streptococcus, it hasbeen found to be due to infections by several monomicrobialorganisms, including S . aureus and Clostridium perfringens(69%). Often, there is polymicrobial infectionthat is most frequently due to Staphylococcus epidermidis ,beta-hemolytic strep, Enterococcus organisms, E . coli,Proteus mirabilis, Klebsiella pneumoniae, Pseudomonasaeruginosa , and species of Streptococcus, Bacteroides, Prevotella, and Clostridium , as well as anaerobic cocci andfungi. Aerobic and anaerobic organisms may be found incombination. Each of the other studies mentioned arerelevant, but none is diagnostic. The differential diagnosisincludes uncomplicated cellulitis caused by group Abeta-hemolytic strep and phlebitis. However, becausenecrotizing soft tissue infection, also called necrotizingfasciitis, is often so devastating in its course, suspicionmust yield to surgical debridement. Biopsy permits thediagnosis of the etiologic organisms and of the pathophysiology.When the diagnosis is made, then the cornerstoneof success in prevention of deaths and amputations isearly debridement.6. The answer is C. RMSF is a leading candidate for thecause of the symptoms and signs portrayed in the vignette,based on the rash, headache, and respiratory symptoms.The blanching macular rash evolves into a petechial eruption.The cause is Rickettsia rickettsii , passed through thebite of a tick with an incubation period of 7 to 14 days.The ticks that carry the rickettsia are by Dermacentorandersoni in the western states and by Dermacentor variabilisin the east (where the most cases are found). Contraryto the implications of its name, 56% of cases occur inone of five states, North Carolina, South Carolina, Tennessee,Oklahoma, and Arkansas. Up to 40% of patients donot recall the tick bite. There is a 3% to 5% case mortality,