A 16-year-old male patient (59 kg) who presented to his primary care physician with a 3 week history of lethargy and myalgias. His physical examination was notable for a 5-cm bullseye lesion on his right foot, which was thought to be a spider bite. This resolved without treatment after 1 week. He developed a similar lesion on his left forearm, which also resolved on its own after 1 week. Four weeks after his symptoms began, he presented to our institution with a headache, jaw stiffness, and left-sided facial weakness (Bell's Palsy). He had a white blood cell count of 32,000 (normal 4,000-10,000). Lyme titers were positive. A lumbar puncture was performed and he was diagnosed with Lyme meningitis. He was treated with ceftriaxone 2 g intravenously twice a day for 4 weeks.The patient developed right upper quadrant pain 1 week after completing his treatment. The pain was intermittent and gradually became more severe over the next 2 weeks. He was seen again at our institution and an abdominal ultrasound was performed. It showed multiple gallstones with one gallstone in the gallbladder neck and mild gallbladder wall thickening (4 mm). There was no pericholecystic fluid and the common bile duct appeared normal. Due to his persistent and worsening symptoms, he underwent a laparoscopic cholecystectomy. He had a significant amount of inflammation around the gallbladder with indiscernible anatomy, and thus we converted to an open procedure.The pathological analysis showed acute necrotizing cholecystitis with surface erosions. The stone analysis by polarization microscopy and infrared spectroscopy revealed that the stone composition was 100% ceftriaxone (Laboratory for Stone Research, Newton, MA, USA).
DiscussionCeftriaxone is a parenteral broad-spectrum, semi-synthetic third generation cephalosporin. A b-lactam antibiotic, it exerts its antibacterial activity through the inhibition of bacterial cell-wall synthesis. Its spectrum of activity includes many gram-positive aerobic bacteria, gram-negative aerobic bacteria and some anerobes. It is resistant to degradation by most bacterial b-lactamases [6]. Ceftriaxone's pharmacokinetic properties are nonlinear and all basic pharmacokinetic parameters (e.g. absorption and distribution), with the exception of the elimination half-life, are dose dependent. Its long halflife of elimination (i.e. 5.4 -10.9 h) allows for once or twice daily dosing.Although it is largely excreted in the urine, 10-40% is excreted unmetabolized in bile [5,7,17,22,29]. It is reversibly bound to albumin, and the binding decreases with the increase in concentration, e.g. from 95% binding at plasma concentrations less than 100 mg/l to 85% binding at 300 mg/l [17]. Due to the lower albumin content in interstitial fluid, the percentage of free drug in interstitial fluid is correspondingly higher than in plasma. As a result, the levels of ceftriaxone in the bile is 20-150 times greater than in serum [25]. As an anion, it binds to calcium and forms an insoluble calcium-ceftriaxone salt in a 1:1 molar ratio that is...