Abstract:
Background: Emergence of multidrug-resistant bacteria and increasing rates of antibiotic
resistance necessitate more judicious use of antibiotics. Overuse, underuse or misuse of antibiotics
may lead to antibiotic resistance. Overuse of antibiotics can be assessed by calculating the multi
drug resistance index.
Objectives: To determine the multidrug-resistance (MDR), extended drug resistance (XDR) and
pan drug resistance (PDR) patterns among bacterial isolates of blood, and to determine the
multidrug resistance index (MDRI) at Teaching Hospital Karapitiya (THK)
Methods: A total of 423 antibiotic sensitivity results of blood culture isolates were extracted at
Microbiology Laboratory, THK from January to June 2022. Extracted data was explored for the
detection of MDR, XDR, and PDR of frequently isolated organisms. MDR was defined as
acquired non-susceptibility to at least one agent in three or more antimicrobial categories, XDR
was defined as isolate resistant to at least one agent in all but two or fewer antimicrobial
categories and PDR was defined as isolates resistant to all agents in all antimicrobial categories.
MDRI was used to determine the usage of antibiotics. A value of MDRI=0.2 was used as the cut
off to denote high-level use of antibiotics.
Results: Of all blood culture isolates, Gram-negatives (81.3%) were higher than Gram-positives
(18.7%). Escherichia coli (25.1%) and Staphylococcus aureus (22.2%) were the predominant
Gram-negative and Gram-positive pathogens, respectively. Majority were multidrug-resistant
bacteria (57.6%). Considering all MDR Gram-negatives, Klebsiella spp. (72.7%) was the
predominant isolate followed by Acinetobacter spp. (68.2%) and E. coli (66.0%). Of all MDR
Gram-positives, S. aureus was the commonest (47.9%). A total of 68.6% isolates had a MDRI of
>0.2.
Conclusion/s: The majority of blood culture isolates were multidrug resistant and showed high
MDRI indicating the necessity for immediate and effective measures to reduce misuse of
antibiotics, thereby combating antimicrobial resistance.
Keywords: Antibiotic resistance patterns, Extended drug resistance, Multidrug-resistance,