Persistent Bacteremia fromPseudomonas aeruginosawithIn VitroResistance to the Novel Antibiotics Ceftolozane-Tazobactam and Ceftazidime-Avibactam.
Ceftazidime-avibactam and ceftolozane-tazobactam are new antimicrobials with activity against multidrug-resistantPseudomonas aeruginosa. We present the first case of persistentP.aeruginosabacteremia within vitroresistance to these novel antimicrobials. A 68-year-old man with newly diagnosed follicular lymphoma was admitted to the medical intensive care unit for sepsis and right lower extremity cellulitis. The patient was placed empirically on vancomycin and piperacillin-tazobactam. Blood cultures from Day 1 of hospitalization grewP.aeruginosasusceptible to piperacillin-tazobactam and cefepime identified using VITEK 2 (Biomerieux, Lenexa, KS). Repeat blood cultures from Day 5 grewP.aeruginosaresistant to all cephalosporins, as well as to meropenem by Day 10. Susceptibility testing performed by measuring minimum inhibitory concentration byE-test (Biomerieux, Lenexa, KS) revealed that blood cultures from Day 10 were resistant to ceftazidime-avibactam and ceftolozane-tazobactam. The Verigene Blood Culture-Gram-Negative (BC-GN) microarray-based assay (Nanosphere, Inc., Northbrook, IL) was used to investigate underlying resistance mechanism in theP.aeruginosaisolate but CTX-M, KPC, NDM, VIM, IMP, and OXA gene were not detected. This case report highlights the well-documented phenomenon of antimicrobial resistance development inP.aeruginosaeven during the course of appropriate antibiotic therapy. In the era of increasing multidrug-resistant organisms, routine susceptibility testing ofP. aeruginosato ceftazidime-avibactam and ceftolozane-tazobactam is warranted. Emerging resistance mechanisms to these novel antibiotics need to be further investigated.
Department of Internal Medicine, Yale New Haven Health-Bridgeport Hospital, Bridgeport, CT, USA.
Louie Mar
0000-0002-6714-9294
LM
Gangcuangco
Department of Microbiology, Yale New Haven Health-Bridgeport Hospital, Bridgeport, CT, USA.
Patricia
P
Clark
Department of Microbiology, Yale New Haven Health-Bridgeport Hospital, Bridgeport, CT, USA.
Cynthia
C
Stewart
Department of Internal Medicine, Yale New Haven Health-Bridgeport Hospital, Bridgeport, CT, USA; Internal Medicine and Infectious Disease Associates P.C., Stratford, CT, USA.
Goran
G
Miljkovic
Department of Internal Medicine, Yale New Haven Health-Bridgeport Hospital, Bridgeport, CT, USA; Internal Medicine and Infectious Disease Associates P.C., Stratford, CT, USA.
Zane K
ZK
Saul