INFECTIOUS DISEASE 1

A 54-year-old male comes to you with complaints of fever, exertional dyspnea and a non-productive cough for one week. He was diagnosed with HIV infection three years ago; however he has been asymptomatic. His vitals are, T: 38.9C(102F), RR: 28/min, PR: 100/min, and BP: 120/80 mm Hg. He is hypoxic at 80% saturation on room air; using a 100% non-rebreather mask, his oxygen saturations increased to 92%.
Lab results are:

Hb: 11.5 g/dL
WBC: 7,000/cmm; no band forms
Platelets: 130,000/cmm
ABG on room air:
pH: 7.46
PO2: 60 mm Hg
PCO2: 32 mm Hg
The chest-x ray shows a diffuse bilateral interstitial infiltration. His CD4 count is 190/µL and the LDH is 400 U/L. What is the most appropriate next step in this patient?

A. Initiation of antiretroviral (HAART) treatment
B. Intravenous ceftriaxone
C. Intravenous pentamidine and steroids
D. Trimethoprim-sulfamethoxazole and steroids
E. Trimethoprim-sulfamethoxazole alone

the answer is D. Trimethoprim-sulfamethoxazole and steroids

Explanation:

PCP (pneumocystis carinii pneumonia) is a hallmark manifestation of AIDS. It is one of the most common opportunistic infection seen in AIDS, mostly associated with CD4 count < 200/µL. The diagnosis should be considered in any HIV patient who presents with dry cough, exertional dyspnea and fever. Chest x- ray usually shows bilateral interstitial infiltrates. PCP is also indicated by the symptom of hypoxia, which may be more severe than expected from radiographic findings. Serum LDH levels are frequently elevated and diagnosis is confirmed by demonstration of organism in sputum or BAL aspirate. The bacterial pneumonia should be considered if the patient has a productive cough, hemoptysis (also TB), a focal infiltrate on the chest-x ray, and an elevated white count with left shift. A chest-x ray finding of hilar adenopathy with diffuse pulmonary infiltrates suggests histoplasmosis, cryptococcosis, mycobacterial infection, or neoplasm. Trimethoprim-sulfamethoxazole is the initial drug of choice in PCP irrespective of the severity of the pneumonia. Steroids have been shown to decrease mortality in cases of severe PCP. Indication of steroid use in PCP includes:
1. PaO2 < 70mm Hg.
2. A-a gradient > 35.
This patient has a PaO2 < 70 mm Hg, and thus steroid use is indicated in this patient.
(Choice A) Though initiation of antiretroviral treatment is indicated in this patient, it is important to start TMP-SMX with steroid first to deal with the PCP and prevent mortality. Failure to start PCP treatment is associated with almost 100% mortality.
(Choice B) Ceftriaxone can be given if this patient has evidence of bacterial pneumonia. His white count is normal. He has a non-productive cough. His chest-x ray is not suggestive, either. Even if this is a bacterial infection, ceftriaxone alone is not sufficient. This, however, is often used, along with azithromycin, to cover the atypical organisms, especially if the patient has community-acquired pneumonia.
(Choice C) Pentamidine is the drug of choice for severe cases of PCP in patients with intolerance to TMP-SMX; however, there is no evidence of intolerance to TMP-SMX in this patient. Pentamidine is comparatively less effective than TMP-SMX.