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2026 Vol.56, Issue 2 Preview Page

Original Article

Occurrence and Antibiotic Resistance Profiles of Bacterial Isolates from Sediments of the Calajunan Sanitary Landfill, Iloilo, Philippines
Ted Rudi Aurelio12
,
Angel Joy Falco3
,
John Kelly Padernilla4
,
Stephen Sabinay45
,
Peter Palma6
,
Rolando Pakingking Jr.127*
1School of Graduate Studies, Central Philippine University, Jaro, Iloilo City 5000, Iloilo, Philippines
2College of Medical Laboratory Science, Central Philippine University, Jaro, Iloilo City 5000, Iloilo, Philippines
3Department of Clinical Laboratory, Capiz Emmanuel Hospital, Inc., Roxas Avenue, Roxas City, 5800, Capiz, Philippines
4Biotechnology and Biomedical Research Laboratory, West Visayas State University, College of Medicine, Luna St., La Paz, Iloilo City, 5000, Iloilo, Philippines
5Physical Sciences Department, College of Arts and Sciences, West Visayas State University, Luna St., La Paz, Iloilo City, 5000, Iloilo, Philippines
6Institute of Aquaculture, College of Fisheries and Ocean Sciences, University of the Philippines Visayas, 5023 Miagao, Iloilo, Philippines
7Life Sciences Department, College of Arts and Sciences, Central Philippine University, Jaro, Iloilo City 5000, Iloilo, Philippines
*rolando102969@gmail.com
10 August 2026. pp. 127-150
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Abstract

Landfill ecosystems are increasingly recognized as environmental reservoirs of antimicrobial resistance (AMR), yet information from the Philippines remains limited. This study characterized the physicochemical properties of landfill sediments and examined their relationships with the cultivable bacterial community and antimicrobial resistance in the Calajunan Sanitary Landfill, Iloilo City, Philippines. Sediment samples were collected from five functional zones representing organic, medical, mixed-waste, and leachate-impacted areas. Significant spatial variation (p < 0.05) was observed in sediment pH, organic carbon, nutrient content, and moisture. Total heterotrophic plate counts ranged from 7.05 to 7.89 log10 CFU/g, with the highest counts recorded in the organic-rich station. A total of 489 bacterial isolates were recovered and identified by biochemical characterization and 16S rRNA gene sequencing (99.63–100% sequence similarity). The cultivable bacterial community was dominated by Bacillus spp., together with opportunistic Gram-negative genera including Aeromonas, Citrobacter, Enterobacter, Klebsiella, Morganella, Proteus, Providencia, and Pseudomonas. Spearman's correlation analysis identified organic carbon, total nitrogen, pH, and calcium as the sediment properties most closely associated with bacterial distribution. Following exclusion of intrinsic resistance according to current EUCAST recommendations, acquired resistance was most frequent against β-lactams, macrolides, aminoglycosides, nitrofurans, and tetracyclines. MAR indices ranged from 0.1 to 0.8, with most bacterial taxa exhibiting values ≥0.2 and several species exhibiting values ≥0.4. This study provides the first baseline characterization of cultivable landfill bacterial communities in Western Visayas and demonstrates that landfill sediments are important environmental reservoirs of antimicrobial-resistant bacteria, supporting their inclusion in One Health-based AMR surveillance.

Keywords
Antimicrobial resistance
Landfill sediments
Bacterial diversity
Multiple antibiotic resistance (MAR) index
One health framework
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Information
  • Publisher :The Korean Society for Microbiology and The Korean Society of Virology
  • Publisher(Ko) :대한미생물학회‧대한바이러스학회
  • Journal Title :JOURNAL OF BACTERIOLOGY AND VIROLOGY
  • Volume : 56
  • No :2
  • Pages :127-150
  • Received Date : 2026-05-26
  • Revised Date : 2026-07-12
  • Accepted Date : 2026-07-31
  • DOI :https://doi.org/10.4167/jbv.2026.56.2.127
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