A 32-year-old woman comes to the hospital complaining of fever, chills, pleuritic chest pain, and shortness of breath for the last 3 days. She was found to be HIV positive 1 year ago; her CD4 count was 378/µL about 1 month ago. The patient does not regularly attend clinic appointments and takes no medications. She uses intravenous heroin and cocaine. Her only sexual partner is also HIV positive. Her temperature is 39.3° C (102.7° F), blood pressure is 120/68 mm Hg, pulse is 110/min, and respirations are 22/min. Examination shows scattered crackles in both lung fields. Her abdomen is soft and nontender without hepatosplenomegaly. Her extremities exhibit several needle marks. Laboratory results are as follows: Imaging of the chest reveals multiple nodular lesions with small cavities, as shown below.
Which of the following organisms is most likely responsible for this patient's current condition?

Question

A 32-year-old woman comes to the hospital complaining of fever, chills, pleuritic chest pain, and shortness of breath for the last 3 days.  She was found to be HIV positive 1 year ago; her CD4 count was 378/µL about 1 month ago.  The patient does not regularly attend clinic appointments and takes no medications.  She uses intravenous heroin and cocaine.  Her only sexual partner is also HIV positive.  Her temperature is 39.3° C (102.7° F), blood pressure is 120/68 mm Hg, pulse is 110/min, and respirations are 22/min.  Examination shows scattered crackles in both lung fields.  Her abdomen is soft and nontender without hepatosplenomegaly.  Her extremities exhibit several needle marks.  Laboratory results are as follows:  Imaging of the chest reveals multiple nodular lesions with small cavities, as shown below.
   Which of the following organisms is most likely responsible for this patient's current condition?

Quizplus · Accepted Answer

11ec25c8_d44d_fbc9_bc81_df8bedc840cf_MD0003_00 This patient's presentation (pulmonary symptoms, history of intravenous drug abuse with track marks, and cavitary lesions on imaging) suggests septic embolism from infective endocarditis (IE). HIV greatly increases IE risk in intravenous drug users (IVDU), most commonly at the tricuspid valve. Patients typically present with systemic symptoms (eg, fever, chills), pleuritic chest pain, dyspnea, and/or cough. However, there may not be a tricuspid valve murmur on cardiac examination due to the relatively low pressure gradient across the valve. Peripheral manifestations (eg, splinter hemorrhages, Janeway lesions) are also less common in patients with tricuspid valve disease. IE diagnosis in IVDU can be difficult and requires a high degree of suspicion. Septic pulmonary emboli occur in up to 75% of patients with tricuspid endocarditis, most commonly due to Staphylococcus aureus in IVDU with IE. Imaging may show pulmonary septic emboli as pulmonary infiltrates, abscesses, infarction, pulmonary gangrene, or cavities, as seen in this patient's CT scan. These lesions are typically located in lung periphery. CT scan (Choice A) Haemophilus influenzae is a colonizer of the upper respiratory tract. It typically causes upper respiratory tract infections, bronchitis (primarily in patients with chronic obstructive pulmonary disease), and pneumonia. However, H influenzae pneumonia usually presents with noncavitating infiltrates. (Choice B) Patients with chronic lung disease, cigarette smokers, and immunosuppressed patients are more predisposed to Legionella pneumophila infection. L pneumophila is transmitted through contaminated aerosolized water, such as that found in cooling systems. Although cavities can be seen in Legionella pneumonia, they are more often found in immunosuppressed patients receiving corticosteroids. (Choice C) Although pulmonary tuberculosis can cause similar symptoms and present with a cavitary lesion, it typically presents with slowly progressive symptoms of malaise, anorexia, weight loss, fever, and night sweats along with pulmonary findings. In addition, chronic cough, not dyspnea, is usually the most common pulmonary symptom (unless there is extensive disease). Miliary tuberculosis has a different appearance on imaging. Miliary tuberculosis (Choice D) Pneumocystis pneumonia is more common in HIV-positive patients with CD4 <200/µL. Patients typically present with subacute respiratory symptoms with diffuse infiltrates on chest x-ray and an increased alveolar-arterial gradient. diffuse infiltrates (Choice F) Staphylococcus epidermidis is a coagulase-negative staphylococcus associated with infections of prosthetic valves, intravascular shunts, and prosthetic joints. S epidermidis is an uncommon cause of native valve endocarditis seen in IVDU. This organism is normally present on the skin and so is also a frequent contaminant in blood cultures. (Choice G) Streptococcus pneumoniae (pneumococcus) is the most common cause of community-acquired pneumonia. It typically causes lobar pneumonia and rarely causes cavitation. Educational objective: Intravenous drug users are more prone to developing tricuspid endocarditis caused by Staphylococcus aureus. Fragments of the vegetation can embolize to the lungs, causing the characteristic nodular infiltrate with cavitation. References: Article Title The association of septic thrombophlebitis with septic pulmonary embolism in adults. (http://www.ncbi.nlm.nih.gov/pubmed/22611460) Endocarditis in the setting of HIV infection. (http://www.ncbi.nlm.nih.gov/pubmed/15332432)

A 32-Year-Old Woman Comes to the Hospital Complaining of Fever