Abstract

Background:
The virulence of Salmonella sp. is increased by the presence of the mgtC gene, which allows the bacteria to survive in environments with low magnesium levels, such as inside macrophages. Salmonella sp. found on eggshells when they show resistance to three or more classes of antibiotics can be classified as multidrug resistant (MDR) bacteria.

Aim:
This study aims to identify the presence of Salmonella sp. MDR and mgtC gene in chicken egg shell swabs from traditional markets in Surabaya.

Methods:
Swab samples were collected from 160 eggs (80 from broiler chickens and 80 from free-range chickens) in ten traditional markets in Surabaya. Isolation and identification were performed using culture media, including Salmonella Shigella Agar (SSA), Gram staining, Triple Sugar Iron Agar (TSIA), Sulfide Indole Motility (SIM), Simmons Citrate Agar (SCA), Methyl Red and Voges Proskauer (MR-VP), and Urea Agar. Antibiotic sensitivity testing was performed using the disc diffusion method on Mueller-Hinton Agar (MHA). Molecular detection of the mgtC gene was performed using Polymerase Chain Reaction (PCR).

Results:
The results showed that 16.87% (27/160) samples were detected positive for Salmonella sp. All Salmonella sp. isolates (27) showed resistance to Erythromycin (100%). Resistance was also found to Ampicillin (77.77%, 21/27), Tetracycline (29.62%, 8/27), and Ciprofloxacin (18.51%, 5/27). No resistance to Chloramphenicol was found. In addition, 8 of the 27 isolates (29.62%) were classified as Salmonella sp. MDR. The Salmonella sp. MDR isolates also carried the mgtC gene 87.5% (7/8).

Conclusion:
These findings demonstrate the potential global public health threat posed by MDR Salmonella sp. with the mgtC gene, emphasizing the importance of monitoring and controlling antibiotic resistance in humans and animals.

Key words: Eggs, MDR, mgtC, Public health, Salmonella sp.