الفهرس 
Chapter (I): The Genus PseudomonasOnly 14 pages are availabe for public view
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Abstract
Pseudomonas and Acinetobacter spp. were categorized among the ESKAPE pathogens, standing for Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, A. baumannii, P. aeruginosa, and Enterobacter spp., which are the major cause of nosocomial infections all over the world. Treating patients with nosocomial infections caused by these pathogens is usually a challenge due to intrinsic and acquired resistance to the commonly used and affordable antibiotics.
The objective of this study was to isolate Pseudomonas and Acinetobacter spp. from patients at the Menoufia University Hospitals, determine their prevalence in different specimens, assess their antimicrobial susceptibility, detect ESβL and carbapenemase production, and investigate colistin resistance mechanisms.
The study was conducted in the period from April 2021 to March 2023 at Medical Microbiology and Immunology Department, Menoufia University. A total of 285 clinical samples were collected, with urine being the most frequent specimen. from these samples, 50 Pseudomonas and 30 Acinetobacter isolates were obtained. Pseudomonas and Acinetobacter spp. were identified using Vitek-2 automated compact system. The highest isolation rates of both species were found in patients aged 20-65 years, and infections were more prevalent in males. The effects of hospital stay duration and associated co-morbidities were also analyzed.
Regarding Pseudomonas spp., the highest isolation rate was observed in the burn unit, accounting for 34% of the total isolates. This suggests that burn patients are particularly susceptible to infections caused by Pseudomonas. Additionally, 38% of clinical Pseudomonas isolates were obtained from burn swabs, further emphasizing the significance of this pathogen in burn-related infections. In contrast, the highest isolation rates of Acinetobacter spp. were found in the intensive care units (ICUs), with a prevalence of 33.3%. This highlights the propensity of Acinetobacter to thrive in the ICU environment, possibly due to factors such as invasive procedures, lowered patient immunity and prolonged hospital stays. Furthermore, 33.3% of clinical Acinetobacter isolates were derived from urine samples, indicating the involvement of this pathogen in urinary tract infections among hospitalized patients. Among the identified species, Pseudomonas aeruginosa and Acinetobacter baumannii were the most commonly isolated strains, as determined by the Vitek-2 automated compact system.
Antimicrobial susceptibility testing revealed high resistance rates to various antibiotics in both Pseudomonas and Acinetobacter isolates. Pseudomonas isolates were highly resistant to norfloxacin and ofloxacin (76%, for each), while Acinetobacter isolates showed highest resistance to Piperacillin (83.3%) followed by Levofloxacin (73.3%). However, a significant proportion of both species remained susceptible to imipenem, meropenem and doripenem (42%, 52% and 38 % of the Pseudomonas isolates, 40%, 46.7% and 36.7 % of the Acinetobacter isolates, respectively). Multiple drug resistance (MDR), extensive drug resistance (XDR) and pandrug resistance (PDR) were observed in both pathogens. The prevalence of MDR, XDR and PDR among Pseudomonas isolates was 48% vs. 40%, 26% vs. 36.7% and 12% vs. 10%, respectively for Acinetobacter.
ESβL production was confirmed in 44% and 43.3% of Pseudomonas and Acinetobacter isolates, respectively using the cephalosporin/clavulanate combination disk test.
Regarding carbapenem resistance, different phenotypic tests were performed. The disk diffusion screening method detected carbapenem resistance in 48% and 50% of Pseudomonas and Acinetobacter isolates, respectively, while only 38% and 40% of Pseudomonas and Acinetobacter isolates, respectively were confirmed by modified carbapenem inactivation test to be carbapenemase-producers. Statistically significant difference in carbapenem resistance analysis (between the disk diffusion screening method and modified carbapenem inactivation test) was observed among Pseudomonas and Acinetobacter isolates (Kappa test= 0.80). Also, MβLs production was confirmed in only 28% and 23.3% of Pseudomonas and Acinetobacter isolates, respectively by combined imipenem/EDTA synergy disk test. A total of 30 Pseudomonas and 20 Acinetobacter isolates were subjected to multiplex-PCR assay to detect suspected resistance genes, including bla NDM, bla VIM-2 and bla IMP-1 genes. The assay revealed positive results for bla NDM, bla VIM-2 and bla IMP-1 genes in 33.3%, 16.7% and 6.7% of Pseudomonas isolates, respectively and in 25%, 15% and 5% of Acinetobacter isolates, respectively.