5 Discussion:
Pneumocystis, a group of microorganisms causing pneumonia, has traditionally been classified as a fungus due to its similarities to other fungi [6]. However, it is important to note that recent research has revealed that its classification is still a topic of debate in the scientific community [6]. Furthermore, the inability to cultivate Pneumocystis in laboratory conditions poses an additional barrier to studying and understanding this microorganism [6]. Patients with pneumocystis pneumonia (PCP) commonly present with a variety of symptoms, including low-grade fever, productive cough, and shortness of breath. In fact, studies have shown that approximately 80-100% of PCP patients experience low-grade fever, while 95% present with both productive cough and shortness of breath. These symptoms are often nonspecific and can mimic other respiratory conditions, making the diagnosis of PCP challenging [7, 8, 9]. Our patient initially presented with symptoms such as low-grade fever, weight loss, and a productive cough, which persisted despite previous antibiotic treatment.
The diagnosis of PCP poses significant challenges due to the non-specific clinical manifestations that can mimic various infectious disease such as tuberculosis [10, 11]; Nocardia; fungal infections and COVID-19 [12 - 21] as well as non-infectious diseases. Additionally, imaging techniques such as chest X-rays and CT scans are not always definitive in diagnosing PCP. In fact, 25% of initial PCP cases may show normal chest X-ray results, and CT scans may not clearly indicate the type of abnormality. While bilateral interstitial infiltrates are commonly observed in PCP, the radiological findings can also be atypical [22]. In the presented case, the chest X-ray revealed diffuse interstitial prominence with nodular infiltrates which is also can be associated with tuberculosis, fungal infections, Nocardia, sarcoidosis and Metastatic carcinoma with lymphangitis carcinomatosis.
Further investigations, including a CT scan and bronchoscopy, were conducted. The CT scan revealed ground glass opacities with intralobular septal thickening and nodular infiltrates. Bronchial washings were collected for microbiology, culture, and cytology testing. Acid-fast bacilli smear and culture, Nocardia and fungal smears and cultures, and GeneXpert testing for tuberculosis were negative. Additionally, cytology ruled out malignancy but showed a three-dimensional alveolar cast with a honeycomb appearance. Based on the clinical presentation, CT findings, and the presence of honeycomb-like alveolar casts, a presumptive diagnosis of PCP was made. The diagnosis was supported by the patient’s positive HIV status. PCP is an opportunistic infection commonly seen in individuals with weakened immune systems, such as those with HIV/AIDS.
Additionally, Trimethoprim-sulfamethoxazole (TMP-SMX) is considered the first-line treatment for mild-to-severe cases of PCP [13]. The recommended dosage for TMP-SMX is typically 15mg/kg/day. However, intravenous pentamidine is also an effective alternative to TMP-SMX. It should be noted that pentamidine carries a higher risk of adverse events compared to TMP-SMX. For individuals with mild or moderate PCP, the oral alternative regimen is atovaquone. Although atovaquone is less effective than TMP-SMX, it is generally better tolerated [22, 34]. In cases of moderate to severe PCP, which is defined as having an arterial oxygen pressure less than 70 torr on room air and an alveolar-arterial oxygen gradient greater than 35 torr, adjunctive corticosteroid therapy is recommended [23]. In our case, the treatment was initiated with Septran (sulfamethoxazole and trimethoprim) for a total of 21 days, resulting in significant clinical improvement. Follow-up chest X-rays showed resolution of the previously observed abnormalities, and the patient fully recovered.
In conclusion, this case emphasizes the significance of including opportunistic infections, like PCP, in the differential diagnosis of respiratory symptoms in individuals with HIV/AIDS. It is crucial to promptly diagnose and initiate appropriate treatment for improved patient outcomes. Collaboration between pulmonologists, infectious disease specialists, and HIV specialists can greatly assist in accurately diagnosing and managing such cases. The patient’s positive HIV status, along with the clinical presentation, CT findings, and the presence of honeycomb-like alveolar casts, supported the diagnosis of PCP.