A 68-year-old Caucasian woman presented to our emergency department complaining of acute onset of severe abdominal pain in the right lower quadrant that began approximately 48 hours earlier; she had a temperature of 39.1 °C and heart rate of 98/minute. She denied any recent fever, chills, hemoptysis, hematochezia, or change in bowel habits. She had no history of trauma or surgery; she did not take any regular medication; she did not use an intrauterine device (IUD) or other local contraceptive. She had normal sex activity with the same partner (last sexual relationship 20 days before surgery). No relevant history of infection in her family was reported. On her presentation to our emergency room, a physical examination revealed a localized peritonism in the right lower quadrant. At rectal examination, a normal sphincter tone was found with no palpable masses and normal stool. Other features were unremarkable. Laboratory values on admission showed an hemoglobin of 13.3 g/dL, 36.4% hematocrit, with 19.00 × 103/uL white blood cells (WBC). C-reactive protein (CRP) value was 5 mg/dl (normal value < 0.5). A computed tomography (CT) scan (Figure 1) revealed no pathognomonic signs of appendicitis. Due to the diagnosis of acute abdomen, with provisional clinical diagnosis of acute appendicitis and secondary peritonitis, antibiotic treatment with amoxicillin-clavulanate 2 .2 g three times a day was initiated and she was taken to our operating room. During the operation, a small amount of free intra-abdominal fluid was found with uterus, ovaries, and fallopian tubes being macroscopically normal. Appendicitis was therefore suspected and appendectomy was performed. Ascitic fluid culture was sent to the Microbiology Laboratory in suitable means of transport. The sample was processed with the classic method by sowing on culture-enriched media, searching for aerobic and anaerobic bacteria. Streptococcus pneumoniae was isolated after 24 hours of incubation in CO2. The organism was identified as S. pneumoniae 99.9% with matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (bioMérieux Clinical Diagnostics). An antibiotic susceptibility test was performed using E-test method and interpreted using European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines 2017. The organism was susceptible to antibiotics tested with minimum inhibitory concentrations (MICs) of benzylpenicillin 0.01 μg/ml, ampicillin 0.02 μg/ml, linezolid 1 μg/ml, ceftriaxone 0.01 μg/ml, meropenem 0.50 μg/ml, levofloxacin 0.5 μg/ml, clindamycin 0.02 μg/ml, trimethoprim/sulfamethoxazole 0.5 μg/ml, and vancomycin 0.1 μg/ml while blood cultures were negative. Our patient's postoperative course was unremarkable and the antibiotic therapy was stopped after 4 days. She was discharged on the fifth postoperative day asymptomatic with a good performance status. In order to understand the source of this rare form of peritonitis we performed an evaluation of serum oncological markers and immunological status (procalcitonin, interleukin 5, interleukin 10), which were all negative. We also tested markers for HIV and hepatitis C virus (HCV) that gave negative results. A chest CT scan was also performed without any evidence of an active source of infection. Furthermore, histological examination of her appendix did not show signs of appendicitis but revealed a form of peritonitis (Figs. 2 and 3). A 30-day follow-up was performed. At day 10 an evaluation of our patient's immunological status was performed and the results were negative; at day 20 a chest CT was done and results were negative for any source of infection.
Histopathological examination of the appendix without pathological signs (hematoxylin-eosin, ×10)
Histopathological report of appendix and mesenteriolum inflammatory peritoneal reaction with deposits of fibrin and granulocytes (red arrows) either over appendicular (a) and mesenteriolum (b) serosa (hematoxylin-eosin, × 10)
J Med Case Reports. 2019;13(126) © 2019 BioMed Central, Ltd.