A 30-year-old male, with no significant past medical history, came to the emergency department with complaints of fever and chills for a duration of 3 days. He also complained of myalgia and abdominal pain for the same duration. He reported diffuse abdominal pain, which was 6/10 in severity, nonradiating, and not related to food. He also reported 2 episodes of diarrhea without any blood or mucous, brown in color. He denied cough, shortness of breath, chest pain, night sweats, weight loss, history of trauma, extreme exercise, or any history of travel.
His abdominal examination was significant for abdominal tenderness in all four quadrants, but was soft and nondistended and bowel sounds were present. The rest of his examination was unremarkable. Triage vitals were significant for a temperature of 103.3 F, heart rate of 88 beats per minute, respiratory rate of 18 breaths per minute, blood pressure of 109/49, and pulse oximetry of 99% on room air.
Admission laboratory workup revealed leukocyte count of 6.1 x 103 microL (reference range 4.5-11.0 x 103) with 72% neutrophils, hemoglobin of 16.2 g/dL (reference range 13.0-17.0), hematocrit of 48.2% (reference range 39-53), platelet count of 149 x 103 microL (reference range 130-400 x 103), ESR of 4 mm/hr (reference range 0-20), BUN of 34 mg/dL (reference range 8-20), creatinine of 1.8 mg/dL (reference range 0.4-1.3), potassium of 4.7 mmol/L (reference range 3.6-5.1), phosphorous of 3.0 mg/dL (reference range 2.4-4.7), aspartate aminotransferase of 1,146 IU/L (reference range 15-41), alanine aminotransferase of 243 IU/L (reference range 17-63), and creatinine kinase of 39,125 IU/L (reference range 38-398). Urinalysis was significant for large blood, and urine red blood cells were 0-2.
In view of the high-grade fever, we attempted to find an infectious source to explain his history and presentation. Chest X-ray (Figure 1) and CT scan were obtained and showed no signs of pneumonia. Urinalysis and influenza rapid antigen test were performed and did not reveal any abnormalities. CT of the abdomen and pelvis was obtained and did not reveal any focal sources. Stool culture with ova and parasites, blood cultures, urinary toxicology including synthetic THC (K2), HIV, herpes simplex virus, hepatitis panel, Mycoplasma pneumoniae IgM antibody, urine Legionella antigen, QuantiFERON  test for tuberculosis, and TSH were all performed as well. All the test results were negative except immunoglobulin M antibodies for Mycoplasma pneumoniae that were detected by enzyme-linked immunosorbent assay. The antibodies were initially 781 U/mL, which is considered a low positive (reference range 770-950).
Our patient was empirically started on levofloxacin and metronidazole for possible gastroenteritis initially while culture and laboratory results were pending. He was managed for his acute renal failure and rhabdomyolysis with aggressive parenteral hydration. However, he continued to spike fevers during days 1-4 of the admission, but his diarrhea, abdominal pain, and myalgia resolved by day 3. One week later, mycoplasma antibody was recorded again and it was 976 U/ml, which is considered a true positive (reference range 950+). The fact that the antibody titer was trending up was clinically significant for a recent Mycoplasma pneumoniae infection. After mycoplasma was found to be positive, metronidazole was discontinued and he was continued with levofloxacin. His creatinine, liver function tests, and CK trended down to normal reference ranges (Figure 2), and he was discharged on day 9 with planned outpatient follow-up.