Bacteriological Profile and their Antibiotic Susceptibility Pattern in Bloodstream Infections in a Tertiary Care Hospital in North India

Abstract

Blood is a sterile, liquid connective tissue. When infected with microbes, grave consequences can occur, such as shock, multiple organ failure, disseminated intravascular coagulation (DIC), and death. The World Health Organization reported 49 million cases of sepsis and 11 million sepsis-related deaths in 2017, accounting for approximately 20% of deaths annually worldwide. Rapid identification of the causative organism and timely, appropriate treatment are required to reduce mortality due to bloodstream infections. This study was conducted to analyze the patterns of various bacteria causing bloodstream infections and their antibiotic susceptibility patterns. All blood samples received for diagnosing bloodstream infections at the Microbiology Department of Sri Guru Ram Das Institute of Medical Sciences and Research, Amritsar, were included in the study, the duration of which was 1 year, from January to December 2020. Blood samples of 5–10 ml from adult and 5 ml from pediatric patients, were collected under aseptic conditions, stored in BACTEC bottles, and processed in an automated BACTEC system before antimicrobial therapy. After 7 days of incubation, if no microbial growth was observed, the sample was reported as sterile for aerobic organisms. When growth was observed, broth from positive blood culture bottles was subcultured on blood and MacConkey agar for identification and antimicrobial susceptibility testing using Vitek 2 according to CLSI (Clinical Lab Standard Institute) guidelines and the manufacturer’s instructions. A total of 441 (14.5%) bacteria were isolated from 3007 blood samples from patients with suspected bacteremia. Contamination was observed at a rate of 2.5%. Gram-positive cocci (49%) were the predominant organisms recovered, followed by Gram-negative bacilli (34%). Gram-positive cocci were coagulase-negative Staphylococci (46%), Staphylococcus aureus (7%), and Enterococcus spp. (6%). Among the Gram-negative bacilli, E.coli (14%), Klebsiella spp. (13%), Acinetobacter baumannii (7%), Pseudomonas spp. (7%), Salmonella typhi (2%), Enterobacter spp. (1%), and Serratia spp. (1%) and single isolates of Aeromonas spp., Morganella morgani, Pantoea spp., Proteus mirabilis, and Providentia rettgeri were identified. Linezolid, teicoplanin, and vancomycin were the most effective drugs for treating Gram-positive bacteremia. Tigecycline, carbapenems, and aminoglycosides were the most effective treatments for Gram-negative bacteremia. The results stress the need for continued screening and surveillance in routine blood culture techniques to start empiric therapy for bloodstream infections.

Keywords

• bloodstream infections
• vitek-2
• bactec