Not Worth Your Weight in Silver: Stain Negative PCR Positive Pneumocystis Jirovecii Pneumonia

Document Type

Conference Proceeding

Publication Date

4-2023

Abstract

Introduction

Pneumocystis jirovecii, the opportunistic fungal pathogen causing Pneumocystis pneumonia (PCP) in immunocompromised individuals, has been classically described in HIV-positive patients, but can also affect non-HIV patients. However, the classical staining techniques used to diagnose PCP might not be as effective in HIV-negative hosts. Here, we describe a case of an elderly HIV-negative gentleman diagnosed with PCP with the use of PCR.

Case Presentation

A 75-year-old man presented to our hospital with a chief complaint of dyspnea on exertion, a cough for the past week, and pain in his right foot. His symptoms started approximately 2 months prior to presentation when he developed redness and swelling in his right third toe, attributed to gout, which had not improved despite treatment. His medical history was significant for essential hypertension, atrial fibrillation, knee osteoarthritis, and benign prostatic hyperplasia. He did not smoke or use alcohol. His home medications included apixaban, dutasteride, lisinopril, tamsulosin, and verapamil. Moreover, for the past 2 months, the patient had received methylprednisolone 4 mg for 36 days, prednisone 20 mg for 26 days, and colchicine 0.6 mg for 29 days.

On physical examination, lungs were clear to auscultation, with multiple bouts of cough triggered by full inspiration. Erythema, edema, and tenderness to palpation of his right forefoot, right medial calf, and third metacarpophalangeal joint of his right hand were present. Painful oral ulcers were also noted.

Lab findings included WBC 21.8 bil/L, Neu 21.0 bil/L, CRP 232.5 mg/L, ESR 93 mm/hr, and Lactic acid 2.8 mmol/L. CT of his chest with IV contrast revealed: “Predominantly upper lobe airspace disease with associated upper lobe volume loss”. Bronchoscopy with bronchoalveolar lavage and biopsy was also performed.

Extensive rheumatologic as well as infectious workup of the blood, urine, and BAL was negative. Pertinent results were: HSV PCR positivity of the oral ulcers, elevated serum 1,3 b-D-glucan (Fungitell®) (>500 pg/mL), and negative Pneumocystis jirovecii stain on BAL. Send out BAL PCR for PCP returned positive.

The patient had already been started on broad-spectrum antibacterial and antifungal coverage at the time of this result, which included IV TMP-SMX 400 mg every 12 hours.

Discussion

The clinical manifestations of PCP differ considerably in HIV-positive and negative patients. The more severe clinical course in HIV-negative patients has been speculated to be secondary to the more pronounced inflammatory response. Bronchoscopy and BAL with traditional staining (eg: Gomori methenamine silver stain or Giemsa stain) is the diagnostic modality of choice. Lower initial clinical suspicion, lesser pathogen burden (lower stain sensitivity), and higher rates of airway colonization (lower stain specificity) adds to the diagnostic challenges in HIV-negative individuals. Molecular testing, such as PCR, can help increase diagnostic yield. PCR can help rule out PCP with high degree of certainty and help differentiate colonization from active infection (quantitative PCR). 1,3 b-D-glucan (Fungitell®) is a potential tool for screening, with a sensitivity of 94.8% and a specificity of 86.3%. Despite being an established risk factor, there is a need for consensus on dosage of corticosteroids that warrant PCP prophylaxis.

Comments

American College of Physicians Internal Medicine Meeting, April 27-29, 2023, San Diego, CA

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