Philippine Journal of Science
154 No. (3): 571-580, June 2025
ISSN 0031 – 7683

Lou Gene B. Sibal, Glaezel Angelique T. Barredo, Noel G. Sabino, and Marian P. de Leon

 

ABSTRACT

The use of bat fecal materials as a biofertilizer is a common practice for farmers. Bat fecal materials are rich sources of nutrients and minerals. Additionally, plant-growth-promoting bacteria have been found in bat fecal materials. However, these fecal materials can also act as reservoirs of pathogenic and antibiotic-resistant bacteria. In this study, Gram-negative bacteria isolated from bat fecal pellets collected at the Cavinti Underground River and Cave Complex (CURCC), in Cavinti, Laguna, the Philippines, were characterized, screened for antibiotic resistance, and identified. Specifically, 100% (19/19) of the isolates were non-endospore-forming, Gram-negative, and rod-shaped. Of these, 15.79% (3/19) were oxidase-positive and obligate aerobes, whereas 84.21% (16/19) were oxidase-negative and facultative anaerobes. The results of the antibiotic resistance screening using the Kirby-Bauer disk diffusion method showed that 5.26% (1/19) of the isolates were resistant to azithromycin, whereas 52.63% (10/19) were resistant and 10.53% (2/19) were intermediate to ampicillin. Furthermore, 15.79% (3/19) of the isolates exhibited resistance to ampicillin, azithromycin, and sulfamethoxazole-trimethoprim. The results of the phenotypic characterization, BLAST, and the phylogenetic analysis identified some of the antibiotic-resistant isolates as Escherichia fergusonii, Citrobacter freundii, Citrobacter telavivensis, Klebsiella oxytoca, Klebsiella pasteurii, Klebsiella aerogenes, Klebsiella sp., and Pseudomonas paraversuta. These isolates are either known human pathogens (K. aerogenes, K. oxytoca, and C. freundii), both animal and human pathogens (E. fergusonii), or potentially pathogenic species to humans (K. pasteurii, Klebsiella sp., and C. telavivensis). Overall, the results of this study indicate that bat fecal pellets serve as reservoirs for pathogenic and antibiotic-resistant enteric bacteria. This highlights the need for environmental policies that promote the safe use of bat fecal materials as biofertilizers and encourage the proper use of antibiotics to prevent zoonotic diseases and curb the further spread of antibiotic resistance.