الفهرس 
Pseudomonas aeruginosaOnly 14 pages are availabe for public view
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Abstract
P. aeruginosa is a leading nosocomial pathogen with a worrisome
increase in antimicrobial resistance. Infections caused by multidrug-resistant
(MDR) and extensively drug-resistant (XDR) P. aeruginosa are major health
threats due to limited susceptibility to available therapeutic options.
Ceftolozane/tazobactam (C/T) and ceftazidime/avibactam (CAV/AVI), two
novel combinations of cephalosporins and β lactamase inhibitors were
recently approved for treatment of multidrug-resistant Gram-negative
pathogens.
This study was performed at the Medical Microbiology and
Immunology Department, Faculty of Medicine, Menoufia University with the
main objectives to study different resistance mechanisms contributing to MDR
and XDR P. aeruginosa phenotypes and to assess their biofilm-forming ability
by the corresponding phenotypic methods. Additionally, the role of efflux
pump-mediated colistin resistance and the presence of type III secretion
system exotoxins genes (exotoxin U & exotoxin S) in MDR/XDR P.
aeruginosa isolates were explored. A major goal of the current study was to
assess the in vitro activity of the second generation β-lactam/beta-lactamases
inhibitor combinations; C/T and CAV/AVI against MDR/XDR P. aeruginosa
isolates expressing variable resistance and virulence traits from patients with
hospital-acquired infections (HAIs) at Menoufia University Hospitals
(MUHs).Also, to detect the synergistic activity of CAZ/AVI plus aztreonam
(ATM) combination against MβL producers.
This study was conducted during the period from May 2021 to
November 2022 involving a total of 313 hospitalized patients (210 males and
103 females with a mean age of 44.13 ±18.38 years). selected patients were admitted to different departments and ICUs of MUHs with different types of
infections that became evident 48 hours or more after hospital admission.
A total of 80 P. aeruginosa isolates were obtained from the different clinical
samples. P. aeruginosa infections were more common among males (60.2%),
patients aged from 18-60 years (58.8%), smokers (75%), who stayed in
hospitals from 7 to 14 days (62.4%), used antibiotics (100%), exposed to
invasive procedures (100%) and had associated co-morbidities (71.3%). About
41.2% (33/80) of P. aeruginosa isolates were obtained from ICUs. The
highest rate of P. aeruginosa isolation was from urine (22/80; 27.5%).
Antimicrobial susceptibility screening revealed high resistance rates to various
antibiotics against P. aeruginosa isolates. About 75% of P. aeruginosa
isolates were resistant to gentamicin followed by resistance rates of 73.8%,
73.8%, 70%, 68.7%, 67.5% and 66.3% for ceftazidime, tobramycin,
imipenem, doripenem, meropenem and cefepime respectively. About 63.7%,
58.7%, 57.5%, 52.4%, 50% of P. aeruginosa were also resistant to aztreonam,
piperacillin, amikacin, levofloxacin and ciprofloxacin respectively. However,
a significant proportion remaiSqned susceptible to ceftazidime-avibactam,
ceftolozane-tazobactam and fosfomycin (81.3%, 63.7% & 62.5%,
respectively). The prevalence of MDR, XDR and non-MDR phenotypes
among P. aeruginosa isolates was 32.5%, 52.5% and 15%, respectively. None
of the obtained P. aeruginosa isolates proved PDR phenotype.
ESβL production was confirmed in 12.5% of P. aeruginosa isolates using the
cephalosporin/clavulanate combination disk test. Also, AmpC production was
confirmed in 46.25% of isolates by AmpC disk confirmatory test.