Frequency of positive blood cultures, isolated microorganisms and their antimicrobial susceptibility profile by Bact /Alert and Vitec ۲ systems in Peyvand clinical and special laboratory, a retrospective study

Background and Aim : The aim of this study was evaluation the frequency of positive blood cultures, isolated microorganisms and their antimicrobial susceptibility profile in Payvand clinical and special laboratory.Methods : in this retrospective study, all blood cultures from Apr to Sep ۲۰۱۹ were included in this survey. From each patient, ۱۰ ml of blood sample was collected and inoculated in to blood bottles and incubated in Bact/ Alert system, immediately. All positive cultures were passaged on usual microbiologic cultures for pure colonies. Bacterial identification and antimicrobial susceptibility test (AST) was done based on direct gram stain and automated Vitec ۲ system protocol.Results : of ۳۴ enrolled patients in this study, ۳۲% were blood culture positive. The frequency of isolated bacteriawas: (۴۶%) gram positive cocci, (۳۶%) gram negative bacilli and (۱۸%) candida spp. The most frequent gram negative bacillus was Klebsiella pneumonia and all of gram positive cocci were coagulase negative staphylococcus (CoNS). Two candida isolates were: C. tropicalis and C. parapsillosis. All gram positive cocci were resistant to erythromycin. All of gram negative isolates were resistant(R) to tested antibiotics except ۳ isolates which were susceptible(S) to amikacin. Only C. parapsillosis showed intermediate susceptibility to caspofungin and micafungin.Conclusion : the predominance of gram positive cocci vs. gram negative bacilli in this study was in accordance other studies. The high resistance rate to common tested antibiotics in gram negative isolates is alarming.

Keywords:

blood culture , antimicrobial susceptibility test , gram negative , gram positive