In Vitro Activity of Ceftolozane-Tazobactam and Other Antibiotics against Pseudomonas aeruginosa Infection-Isolates from an Academic Medical Center in Thailand

Abstract

(1) Background: Resistant Pseudomonas aeruginosa (PA) infections have limited treatment options. Data on the activity of ceftolozane-tazobactam (C-T) against PA in Thailand are limited. Objectives: The objective of this study was to identify the in vitro activity of C-T against general and resistant PA isolates from patients with real clinical infections from the HRH Princess Maha Chakri Sirindhorn Medical Center (MSMC) compared to other antibiotics and to study the resistant molecular patterns of those PA strains which were resistant to C-T. (2) Materials and Methods: This was an in vitro susceptibility study of 100 PA isolates plus an additional seven resistant PA isolates collected from MSMC patients. All PA isolates were tested with susceptibility broth (Sensititre™) and C-T minimal inhibitory concentration (MIC) test strips (Liofilchem, Roseto degli, Abruzzi, Italy). The C-T-resistant PA isolates were analyzed for six β-lactamase genes (blaCTX-M, blaNDM, blaIMP, blaVIM, blaOXA-23 and blaOXA-48) and the mcr-1 gene. (3) Results: A total of 100 PA isolates were collected between January 2020 and January 2021 and between February 2021 and September 2021 for the additional 7 resistant isolates. There were 18 resistant PA isolates (6 MDR, 11 XDR and 1 pan-drug resistant isolate). The overall susceptibility of the initial 100 PA isolates and the 18 resistant PA isolates was 94% and 44.5%, respectively, for C-T. The C-T susceptibility rates for isolates non-susceptible to ceftazidime, piperacillin-tazobactam, carbapenems and antipseudomonal β-lactams were 65.5%, 69.7%, 50% and 44.5%, respectively. Among the 10 isolates which were resistant to C-T, there were only 3 isolates found to have the resistant gene, which included 1 for blaIMP, 1 for blaVIM and 1 for blaNDM. (4) Conclusions: Although C-T was the best susceptibility antibiotic overall for PA isolates and MDR PA isolates at the MSMC, most of the XDR PA isolates and the PDR PA isolate were not susceptible to C-T. The mechanisms for C-T resistance involved multiple factors including the presence of blaIMP, blaVIM and blaNDM.

Ceftolozane/Tazobactam In-Vitro Activity against Clinical Isolates from Complicated Intra-Abdominal Infection Patients in Three Indonesian Referral Hospitals

“…One isolate showed that C/T was the only susceptible antibiotic compared to other antibiotic groups, including carbapenem (meropenem and imipenem). This finding aligns with a previous study that reported that Pseudomonas non-susceptible to meropenem may still be susceptible to C/T [20][21][22]. The high susceptibility against carbapenem-resistant P. aeruginosa was also reported by other studies [23,24].…”

Satisfactory In Vitro Activity of Ceftolozane–Tazobactam against Carbapenem-Resistant Pseudomonas aeruginosa But Not against Klebsiella pneumoniae Isolates

“…A high percentage of strains was confirmed susceptible to tobramycin (91.0%) and ceftazidime (78.0%) too. Similar results were obtained by Tantisiriwat et al [ 27 ] for the strains isolated from different types of clinical samples. Among 100 isolates, 94.0% were susceptible to C/T, and 18.0% were defined as MDR.…”

Editorial for the Special Issue: “Epidemiology, Prognosis and Antimicrobial Treatment of Extensively Antibiotic-Resistant Bacterial Infections”

“…Also within this Special Issue, Losito AR et al discuss treatment options for difficult-to-treat P. aeruginosa , namely: novel β-lactam/β-lactamase-inhibitor combinations (ceftolozane/tazobactam, ceftazidime/avibactam and imipenem/relebactam, as well as combinations in the pipeline), cefiderocol, and fosfomycin-based combinations [ 8 ]. Of particular note is that ceftolozane/tazobactam activity may be reduced against P. aeruginosa isolates co-resistant to all other anti-pseudomonal β-lactams, as shown by Tantisiriwat W et al [ 9 ]. Moreover, none of the currently available β-lactam/β-lactamase combinations are active against metallo-β-lactamase producing P. aeruginosa [ 3 ].…”