*Corresponding Author: Alia A. Shoeib Plant Pathology Dept., Faculty of Agriculture, Alexandria University, Egypt. E-mail: aliashoeib@alex-agr.edu.eg/aliashoeib7@yahoo.com Research Article Volume 2012, Article ID sjmb-112, 13 Pages, 2012. doi: 10.7237/sjmb/112 Science Journal of Microbiology Published By Science Journal Publication ISSN: 2276-626X http://www.sjpub.org/sjmb.html © Author(s) 2012. CC Attribution 3.0 License. A Study of Epidemiology and Etiology of Bacteremia Isolates from Patients in Riyadh City of Saudi Arabia Roua M. S. Alkufeidy 1 Alia A. Shoeib 1, 2* Ali M. Somily 3 1 Botany and Microbiology Dept, College of Science, King Saud University, Saudi Arabia 2 Plant Pathology Dept., Faculty of Agriculture, Alexandria University, Egypt 3 Dept. of Pathology, College of medicine, King Saud University, Saudi Arabia Accepted 27 th November, 2012 ABSTRACT Aim: Detection of the interface between etiological agents of bacteremia and epidemiology. Methods: A total of 164 blood samples were collected from patients infected by bacteremia in King Khalid University Hospital, Riyadh, Saudi Arabia. Special bottles of BACTEC/ALERT PF microbial detection System (BIOMÉRIEUX brand) were used as blood culture bottles with antimicrobial removal systems. Bacterial species were identified using cultural, morphological and standard biochemical tests e.g. the oxidase, catalase and Indole tests. Results: Elderly category of age was the highest (38.3%), compared to the adult's category (33.2%), then came the other categories (infants, pediatrics, teenagers) which were statistically equal (13.2, 11.0, and 4.3% respectively). The average of infected people in an Inpatient Departments (38.7%) was higher incorporeal than infected people in an Outpatient Departments (11.3%). Identification of bacterial genus and species according to the biochemical definition prospects was carried out in Hospital’s Bacteriology Lab. Pathogens were identified in 173 organisms of Gram Positive, Gram Negative bacteria and yeasts. The patients can be infected by one or more than one pathogenic bacteria. The statistical analysis showed a non significant difference between the infected patients by either G ــ ve or G + ve in both males and females. Conclusion: Patients can be infected by one bacterium, more than one bacterium or yeast. E. coli and Staphylococcus sp. exhibited significant differences in comparison with other genera (G – ve and G + ve respectively) isolated from blood. KEYWORDS: Epidemiology, Etiology, age categories, Bacteremia, E. coli, Staphylococcus INTRODUCTION Blood is still the richest environment for many bacteria to grow to cause bacteremia. It leads to the possibility of microbial infection, serious blood diseases which are incurable and sometimes transmitted in the present age through blood transfusions (Volk et al., 1986) and they commonly spread in hospital (Mylonakis et al., 2006). For reviewing the present work, a variety of studies was addressing the issue. Comparison between episodes of bacteremia and fungemia in children and adults with cancer to assess differences in etiology (Rahbar et al., 2005), risk factors (Llop et al., 2001), outcome (Krupova et al., 1998) and determination whether the organisms in the bloodstream originated from the patient's own flora (von Eiff et al., 2001) were reported. Etiological agents of Bacteremia were studied by many researchers, who confirmed that Neisseria meningitidis was the most common species in community-acquired infections, and staphylococci predominated in hospital-acquired episodes (Gray et al., 2001), whereas Rahbar et al., (2005), reported that Gram + ve cocci, including coagulase-negative staphylococci, Staph. aureus, Streptococcus pneumoniae and Gram - ve bacilli, particularly P. aeruginosa, were responsible of Bacteremia isolates. While, results from Berezin and Iazzetti (2006) showed that the most common etiologic agent was S. pneumoniae. From previous studies the relationship between Bacteremia and serious diseases with the causal agent was reported in Seydi et al., (2005) in cases of E. coli bacteremia was associated with meningitis and AIDS, Ekkelenkamp et al., (2007) reported that Staph. aureus bacteremia causes Staph. aureus bacteriuria, otherwise, Alamgir et al., (2006) found