A 26-year-old female of Hellenic ethnicity was admitted to our outpatient clinic, reporting a 10-day history of low grade fever, chills, nausea, headache, urge to vomiting, and a dull pain over the right kidney area. Her past medical history was free of any chronic or acute infection or systemic disease, except for a prior admission to our hospital 1 year ago due to diarrhea not associated with any specific microorganism.
Her physical examination revealed temperature of 38 C, normal blood pressure (110/70 mmHg), and tachycardia (HR = 160 bpm). During palpation, a slight pain in right upper abdominal area was revealed with no other specific signs and symptoms. The respiratory examination was remarkable for dullness to percussion with decreased breath sounds over the lower right lung base. The remainder of the physical examination was unremarkable. Initial laboratory findings revealed a polymorphonuclear leucocytosis of 13.700/mm3 with 72% neutrophils and 18% lymphocytes, ESR of 29 mm/hr, and C-reactive protein of 5.31 mg/dL. No other pathological findings were indicated from the biochemical testing. Detailed investigations did not reveal any predisposing factors or evidence of an underlying immunodeficiency. More specifically, there was no evidence of malnutrition, no history of therapy with glucocorticoids or other immunosuppressive drugs, and no indication of immunoglobulin excess or deficiency through quantitative serum immunoglobulin tests, and blood tests were negative for chronic infections (HIV, viral hepatitis, etc.) or autoimmune disorders (antinuclear antibodies and other autoantibodies). Chest X-ray examination showed pneumonic infiltration in the lower one-third of the right hemithorax and laterally located dense appearance resembling left pleural effusion. Based on this evidence, the patient was diagnosed as having community-acquired pneumonia and after blood cultures were taken, antimicrobial treatment was initiated with intravenous ceftriaxone 1 gr/day + azithromycin 500 mg/day. Sputum, protected specimen brush (PSB) material of bronchial secretions, and three sets of blood specimens were also taken on admission for cultures which did not yield any pathogens.
Within the following two days, the patient's fever rose to 40 C despite the administration of antimicrobial therapy, and her condition deteriorated by developing dry cough, chest pain, total absence of breath sound during auscultation in right hemithorax, and dyspnea. Additionally, a strong right lumbar pain appeared. Three additional sets of blood cultures, taken while the patient was febrile, were negative.
On the third day, computed tomography (CT) scanning of the chest was performed and revealed a lung thick-walled abscess formation in the right lower lobe, with a surrounding inflammatory infiltrate, extended atelectasis, and pleural effusion to the right lower lobe. Figures 1(a) and 1(b) exhibit the size and morphology of the lung abscess. A subsequent ultrasound examination of the patient's liver, carried out in order to examine whether there was any subdiaphragmatic extension or origin of the infection, did not reveal any relevant evidence.
The combination of ceftriaxone + azithromycin was consequently discontinued and replaced by moxifloxacin 400 mg/day + tazobactam plus piperacillin (0.5 + 4.0) gr x 3/day + clindamycin 600 mg x 3/day. PCR for tuberculosis was performed and anti-Echinococcus IgG and IgM antibody titers were measured; however all the results were negative.
The next days, her fever did not subside, CRP levels rose gradually to 16.85 mg/dL, and the pleural effusion continued to rise. Blood cultures remained all negative for any bacterial growth.
On the sixth day of admission, the patient underwent lobectomy, owing to the lack of response to antibiotic therapy, the deterioration of symptoms, and the difficulty in approaching the specific lobe area by thoracentesis. Approximately 700 mL of pleural fluid was collected and sent to laboratory for biochemical analysis, Gram stain, cultures, and antimicrobial profile. Biochemical analysis of the pleural fluid showed the following: glucose of 74 mg/dL, lactate dehydrogenase of 730 U/L, total protein of 3.9 g/dL, and white blood cell count of 15.400/mm3 with 80% polymorphs. Gram staining and cultures of the pleural fluid were negative. In addition, the aspiration of the abscess revealed yellowish pus (about 45 mL) that was also sent for laboratory analysis the same day. Cultures of the pus sample collected from the abscess yielded a Gram-negative aerobic rod identified as Salmonella enterica subsp. enterica serovar Abony. Salmonella isolate was identified to the genus level by both the automated Vitek-2 System (bioMerieux, Inc., Hazelwood, MO) and the API 20E (bioMerieux, Inc., Hazelwood, MO). Serotyping of the isolate was performed using the somatic O and flagellar H antisera according to the Kauffman-White classification scheme (Difco Laboratories, Detroit, MI, USA). Molecular confirmation of Salmonella serotyping was carried out using the DNA microarray system Premi-Test  Salmonella (DSM Nutritional Products, Check-Points, Wageningen, Netherlands). Antimicrobial susceptibility testing was initially performed by the Vitek-2 System, according to the recommendations of the National Committee for Clinical Laboratory Standards and confirmed by E-test (bioMerieux, Inc., Hazelwood, MO). The isolate was susceptible to commonly used antibiotics (ampicillin MIC of 0.75 mug/mL, ceftriaxone MIC of 0.085 mug/mL, cefotaxime MIC of 0.082 mug/mL, ceftazidime MIC of 0.115 mug/mL, ciprofloxacin MIC of 0.032 mug/mL, moxifloxacin MIC of 0.016 mug/mL, and trimethoprim-sulfamethoxazole MIC of 0.064 mug/mL). Based on the laboratory report, the antimicrobial therapy was changed on the eighth day after admission, to sulfamethoxazole/trimethoprim (800 + 160) mg x  2/day, moxifloxacin 400 mg/day, and clindamycin 600 mg x 3/day, along with supportive therapy.
The postoperative clinical condition of the patient improved noticeably. Six days after surgery, the patient's symptoms resolved and she was discharged on sulfamethoxazole/trimethoprim (800 + 160) mg x 2/day and ciprofloxacin 500 mg x 2/day, for 20 days.