48.The answer is b.(Rosen, pp 986-998.) Undomiciled,alcoholic
patientsare at particular risk for contracting K pneumoniae. Classically, it
presents with a productive cough with currant jelly sputum,fever, general
malaise, and an overall toxic appearance. A dense lobar infiltrate with a bulging
fissure appearance on a chest radiograph is often described.
Streptococcus pneumoniae(a)is the most common etiology in community-
acquired pneumonia among adults. Mycoplasma pneumoniae(c)is a common
cause of community-acquired pneumonia in patients under the age of 40.
Legionellapneumophila(d)is an intracellular organism that lives in aquatic
environments and is not transmitted from person to person. Haemophilus
influenzae(e)is common among patients with chronic obstructive pul-
monary diseases (COPD), alcoholism, malnutrition, or malignancy. It is a
pleomorphic gram-negative rod that can be encapsulated and identified as
various serotypes, with type b as the most commonly causing bacteremia.
49.The answer is e.(Rosen, pp 388-391, 1000-1005.)Aspontaneous
pneumothoraxtypically presents with ipsilateral pleuritic chest painand
dyspnea while at rest. Physical findings tend to correlate with the degree of
symptoms. Mild tachycardia, decreased breath sounds to auscultation, or
hyperresonance to percussion are the most common findings. It typically
occurs in healthy young men of taller than average stature without a pre-
cipitating factor. Mitral valve prolapse and Marfan syndrome are also asso-
ciated with pneumothoraces. The most common condition associated with
secondary spontaneous pneumothorax is COPD. Although suggested by
this patient’s symptoms, the diagnosis of pneumothorax is generally made
with a chest radiograph. The classic sign is the appearance of a thin, vis-
ceral, pleural line lying parallel to the chest wall, separated by a radiolucent
band that is devoid of lung markings. If clinical suspicion is high with a
negative initial chest x-ray, inspiratory and expiratory films, or a lateral
decubitus film may be taken to evaluate for lung collapse.
An ECG (a)may be performed at a later time to investigate this patient’s
symptoms, but given the high likelihood of pneumothorax, a chest radi-
ograph should be done first. A D-dimer (b)is a blood test used as a screening
tool in patients who have a low pretest probability for a thromboembolism.
A negativeD-dimer can exclude the diagnosis of PE in patients with a low
pretest probability. If the chest radiograph is unremarkable in this patient,
sending a D-dimer may help in the workup of his dyspnea. A V/Q scan
(c)also aides in the diagnosis of PE. Because spiral CT angiography has
emerged as a test with high sensitivity and specificity, V/Qscan are being
64 Emergency Medicine