الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Ventilator associated pneumonia is defined as pneumonia that occurs 48-72 hours or thereafter following endotracheal intubation. It is characterized by the presence of a new or progressive infiltrate, signs of systemic infection, changes in sputum characteristics, and detection of a causative agent. It has been reported to occur in 9-40% of intubated patients. The aim of our study was to detect the distribution of adhesive and non-adhesive virulence factors in A. baumannii isolated from respiratory samples of VAP cases.
Thirty A. baumannii isolates were collected from ETA samples. Samples taken from hospitalized and mechanically ventilated cases for more than 48 hours were eligible for the study if pneumonia was suspected on clinical criteria. 110 cases from different ICUs in Alexandria were included in the study; ETA samples were collected from patients in ICU at different hospitals in Alexandria collected in microbiologcal lab. Identification of A. baumannii was done by standard microbiological methods, including morphology culture characteristics, Gram stain, biochemical tests. Susceptibility of A. baumannii isolates to different antibiotics were done according to corresponding CLSI.
A. baumannii isolates were confirmed molecularly by detection of A. baumannii 16S-23S ribosomal RNA using conventional PCR. Detection of genes coding for adhesive virulence and non-adhesive virulence factors were done using multiplex PCR.
Respiratory ET samples were cultured on: Blood agar, MacConkey’s agar, Sabouarud’s dextrose agar. After Gram stain and routine biochemical tests 30 isolates of Acinetobacter spp, 25 isolates of Klebsiella pneumoniae, 22 isolates of Pseudomonas spp, 7 isolates of Staphylococcus aureus, 7 isolates of Candida, 6 isolates of E.coli, 2 isolate of Proteus spp, 1 isolate of Enterbacter spp, 1 isolate of Citrobacter freundi, 1 isolate of Providencia spp and 1isolate of Stenotrophomonas spp. were identified. Seven cases showed no growth ―sterile‖.
A. baumannii isolates were identified by conventional methods. Also all thirty A. baumannii isolates were confirmed Genotypically by detection of A. baumannii 16S-23S ribosomal DNA by conventional PCR.
Regarding demographic classification of VAP with A. baumannii infection; the gender and age distribution of the cases were studied and it was found that 70% of the patients were males while 30% were females and 18(60%) were above 60 years. As regarding to VAP classification of patients with A. baumannii infectionand history of antibiotic exposure; Patients with A. baumannii infection who developed pneumonia within 96 hours of mechanical ventilation were classified as ―early-onset VAP‖ & these were 12/ 30 (40%). While those who developed pneumonia after 96 hours were classified as ―late-onset VAP‖ & these were 18/ 30 (60%).
Regarding antibiotic susceptibility all the thirty A. baumannii isolates; All isolates were tested for their antibiotic susceptibility toward 15 antibiotics. The highest resistance to antibiotic was detected among ciprofloxacin 21 (70 %) followed by Imipenem 18(60%), meropenem 18(60%), Ampicillin –sulbactam 16(53.3%). Resistance to cephalosporine ranged from (36.7%-50%) as follow cefepime11(36.7%), ceftriaxone12(40%) and ceftazidime15(50%). Resistance
Summary, Conclusion &Recommendation
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to aminoglycoside ranged from (20%-50%) as follow Amikacin 6(20%), Tobramycin 8 (26.7%) and Gentamycin 15(50%). The A. baumannii isolated strains were also resistant to Levofloxacin 9 (30%), Gatifloxacin 7 (23.3%), Cotrimoxazole 7 (23.3%) and piperacillin/tazobactam 6 (20%). The lowest resistance to antibiotic was detected to Colistin 5 (16.7 %). Regarding prevalence of MDR strains that cause VAP in our study; 18(60%) of A. baumannii isolates were MDR and 12(40%) were NMDR.
All thirty A. baumannii VAP isolates were tested for presence of adhesive and non-adhesive virulence genes by multiplex PCR. The highest prevalence gene was fimbrial adherence gene fimH 9 (30%) followed by afa/draBC, sfa/focDE genes 8(22%) each, fyuA 5(16.67%), kpsM T II 4 (13.33%) and cnf1, cnf2 4 (13.33%) each. Detection of PapG II- III, csgA and papC genes were 3 (10.00%) each. Also cvaC, iutA and ibeA were 2 (6.67%) each. PAI and traTgenes were not detected at all. Overall, Adhesive genes were more detected than non-adhesive genes among A. bauamanii species.
Relation between virulence factors and antibiotic susceptibility; Comparative study between the 2 groups (MDR/ NMDR) revealed that the presence of (afa/draBC and fimH) genes were significantly correlated with MDR (p <0.05 respectively). There was non-significant correlation detected regards all (remaining adhesive and non-adhesive) virulence factors in MDR A. baumannii isolates (p >0.05).
For that this study strongly suggests that enforcing adherence to recommended infection control practices for MDRO control.