Case Presentation: A 51-year-old man with history of alcoholic cirrhosis presented with diarrhea, abdominal pain, fatigue and confusion for one week. Vitals were within normal limits, though the patient reported subjective fevers at home. Physical exam was notable for asterixis and ascites, and a paracentesis was performed. Cell count and culture of his ascitic fluid did not show spontaneous bacterial peritonitis. However, his blood culture was positive for gram-negative rods (GNR), for which he was started on ceftriaxone empirically. CT of his abdomen showed wall thickening of the ascending colon and cecum, and his GNR bacteremia was felt to be due to gut bacteria translocation in the setting of his immunocompromised state from his cirrhosis. On hospital day 3, his initial set of blood cultures was finalized as multi-drug resistant (MDR) Salmonella Typhi. This organism was resistant to amikacin, ampicillin, ampicillin/sulbactam, cefazolin, cefoxitin, ceftazidime, ceftriaxone, gentamicin, and tobramycin, and intermediate to ciprofloxacin; it was susceptible to cefepime, ertapenem, meropenem, piperacillin/tazobactam, and trimethoprim/sulfamethoxazole. Salmonella was also confirmed on his stool GI pathogen nucleic acid detection test. Subsequent blood cultures remained negative. The patient was switched to ertapenem given the susceptibilities. His symptoms resolved with antibiotics and lactulose, and he was discharged after completing 2 weeks of IV ertapenem. Given the resistance pattern of his MDR Salmonella Typhi, the county public health department was notified.
Discussion: Salmonella enterica serotype Typhi (S. Typhi) is a pathogenic bacteria responsible for the enteric fever syndrome, also known as typhoid fever. Although enteric fever is most pertinent in impoverished areas of the world, there are approximately 200 cases of S. Typhi reported in the U.S. each year. Over 80% of these cases are in individuals with recent travel to endemic areas of enteric fever, such as Southeast Asia or Africa. Treatment of enteric fever may be complicated by the development of multidrug resistant (MDR) and extensively drug-resistant (XDR) strains. S. Typhi strains are considered MDR if they are resistant to chloramphenicol, ampicillin, and trimethoprim-sulfamethoxazole, and as XDR if they are MDR, intermediate or resistant to ciprofloxacin, and resistant to third-generation cephalosporins such as ceftriaxone. While MDR strains have been seen in the U.S., the XDR strain has largely been prevalent in Pakistan, where there was an outbreak from 2016-2018.This case describes an individual with GNR bacteremia, later found to be MDR Salmonella Typhi. Further clarification of his travel history revealed that he had been to Mexico in the last month, but nowhere outside of the U.S. Although his strain of the bacteria was considered MDR, it was unusual in that it was resistant to ceftriaxone and fluoroquinolones yet sensitive to trimethoprim-sulfamethoxazole, unlike the sensitivities seen with prior MDR and XDR S. Typhi outbreaks. Given these sensitivities, it is possible that this may be an emerging strain that is ceftriaxone-resistant, in an area where ceftriaxone resistance in S. Typhi has not been previously reported.
Conclusions: Although ceftriaxone is the antibiotic of choice against Salmonella Typhi in the United States, providers treating patients with suspected enteric fever should obtain a thorough travel history as well as send for antimicrobial susceptibility testing given the public health concerns.