A 45-year-old man with underlying uncontrolled diabetes mellitus, who had stopped taking his daily dose of insulin since the last 4 days, presented with pain in the right abdominal area of one-day duration. He had no fever or any other significant systemic symptoms. He was a known alcoholic, but he had stopped consuming alcohol since the last 4 months. He had no other relevant medical history, including hypertension, history of contact with tuberculosis, or any urinary or bowel complaints. He gave no history of dental extraction or dental manipulation, no surgical history, and no history of bronchoscopy or any respiratory tract manipulation in the recent past. On admission to achieve diabetic control, physical examination revealed a thin-built man (body weight 49 kg) who was awake and oriented to time, place, and person but appeared lethargic and pale. Vital signs included a lowered body temperature of 36.5 C, blood pressure of 126/76 mmHg, pulse of 62/min, and a regular respiratory rate of 18/min. No evidence of dental caries, periodontitis, or any other oral lesions were found. Abdominal examination revealed a soft, nontender, and slightly distended abdomen with no apparent hepatomegaly or splenomegaly.
Blood tests revealed an elevated alanine aminotransferase level of 103 IU/L and slightly elevated aspartate aminotransferase level of 44 IU/L, but normal alkaline phosphatase level of 178 IU/L. Hemogram reports were within normal limits except slight leukocytosis with a total leucocyte count of 11.1 x 109/L (66% polymorphs, 21% lymphocytes, and 9% eosinophils), total red blood cell count of 4.9 x 1012/L, platelet count of 324 x 109/L, and haemoglobin level of 129 g/L. Blood metabolic panel suggested an extremely poor diabetes control with a high random blood sugar level of 299 mg/dL, fasting blood glucose level of 234 mg/dL, and postprandial blood sugar level of 575 mg/dL. Serum electrolytes and other biochemical parameters were within normal limits. The patient tested negative for anti-HIV-1/2 antibodies, anti-HCV antibodies, and for Hepatitis B surface antigen. An ultrasonogram of the abdomen revealed a large well-defined hypoechoic lesion of size 13.8 x 11.6 x 12 cm, with dense internal echoes and debris in the left lobe of the liver suggestive of a large left-sided liver abscess with impending rupture. Pigtail catheterization carried out under local anaesthesia drained approximately 1000 ml of brownish yellow liquid pus, which was sent for routine microbiological investigations including Ziehl-Neelsen stain, wet-mount, and culture for bacteria and fungi (Figure 1(a)). Thereafter, cavity was irrigated, wound drainage was performed, and parenteral antibiotics (ceftriaxone, levofloxacin, and metronidazole) were administered to the patient empirically pending culture results. Simultaneously, glycemic control was optimized with insulin therapy.
Gram smear of the abscess drainage showed polymorphs with lanceolate-shaped Gram-positive cocci, lying in pairs, short chains, and small clusters (Figure 1(b)). The culture yielded pure growth of smooth, dome-shaped, and glistening alpha-haemolytic colonies on blood agar plates after overnight incubation at 37 C in 5-10% carbon dioxide, which on further incubation became flat with raised edges and central umbonation with carrom coin appearance (Figure 1(c)). No growth was observed on the MacConkey agar plate. The organism was catalase-negative, did not hydrolyse bile-esculin, was optochin sensitive, demonstrated bile solubility with 10% sodium deoxycholate solution, and was identified as Streptococcus pneumoniae.
Antimicrobial susceptibility testing using both disk diffusion and Etest (HiMedia, Mumbai, India) to determine, respectively, the zone diameter and minimum inhibitory concentrations (MICs) of various antibiotics showed the isolate to be susceptible to penicillin, ceftriaxone, levofloxacin, ertapenem, meropenem, clindamycin, chloramphenicol, vancomycin, and linezolid and resistant to erythromycin, doxycycline, and trimethoprim/sulfamethoxazole (Figure 1(d)). The MICs (microg/ml) of penicillin, ceftriaxone, ertapenem, meropenem, clindamycin, vancomycin, and linezolid were 0.023, 0.016, 0.012, 0.023, 0.023, 0.5, and 0.19, respectively. Other routine microbiological investigations including blood culture did not reveal any significant finding. Amoebic serology was negative. Ziehl-Neelsen stain did not reveal any acid-fast bacteria. Wet-mount examination showed no trophozoites of Entamoeba histolytica or any fungal element. Antibiotic therapy with parenteral ceftriaxone was continued and clinical and radiological improvement was noted after two weeks, with decrease of abdominal pain and significant resolution of abscess. Parenteral ceftriaxone was administered for a total duration of 4 weeks, after which the patient was discharged, with advice of a 2-week course of oral cefixime. Clinical examination at four months and one-year of follow-up revealed no recurrence of infection or any new serious bacterial infection.