Optimasi Variasi Waktu Perendaman Kertas Saring Menggunakan Ceftriaxone Injeksi pada Diameter Zona Hambat Bakteri Escherichia coli

Background: Antibiotic susceptibility testing is a method used to determine the
sensitivity of bacteria to antibiotics. Escherichia coli is a bacterium commonly
encountered in microbiological examinations and has the potential to cause
infections. Ceftriaxone is an effective antibiotic for the treatment of Escherichia coli
infections. Ceftriaxone discs used for susceptibility testing are relatively expensive
and have limited availability. Therefore, filter paper impregnated with ceftriaxone
injection solution can be used as an alternative to commercial antibiotic discs.
Ceftriaxone injection is more cost-effective and can serve as an alternative to
commercial ceftriaxone discs.
Objective: Determining the optimal soaking time of filter paper in ceftriaxone
injection solution on the inhibition zone diameter of Escherichia coli.
Methods: This study was a pre-experimental study with a static group comparison
design using Escherichia coli as the test bacterium. Each treatment was performed
in 10 replications based on Federer’s formula. The data were analyzed using the
Kruskal-Wallis test followed by Dunn’s post hoc test.
Results: The mean inhibition zone diameter of Escherichia coli using a ceftriaxone
disk was 31 mm, whereas filter paper immersed in ceftriaxone injection solution
for 20, 25, and 30 minutes produced mean inhibition zone diameters of 25.1 mm,
25.6 mm, and 26 mm, respectively. The Kruskal–Wallis test showed a significant
difference among the groups (p < 0.000), and the Dunn post hoc test indicated that
all immersion groups differed significantly from the standard disk group (p < 0.05).
Conclusion: The optimal filter paper immersion time in ceftriaxone injection
solution was 30 minutes, resulting in a mean Escherichia coli inhibition zone
diameter of 26 mm.
Suggestion: Future studies are recommended to evaluate soaking times of up to 1
hour and to assess the potential use of Whatman No. 3 filter paper as an alternative
to commercial antibiotic discs.