Assessment of Selected Bacterial Pathogens at Metrobus Terminal Waiting Rooms in Rawalpindi, Pakistan

Abstract

The study evaluated the bacterial loads in three metro terminals of Rawalpindi analyzing air and surface samples using culture media Nutrient Agar (total bacteria), Eosin Methylene Blue Agar (E. coli), MacConkey Agar (coliform bacteria), and Salmonella Shigella Agar (Salmonella/Shigella). The culture media were prepared on petri dishes and were taken to the respective stations P1 (Saddar), P2 (Mareer), and P3 (Liaquat Bagh). The results of bacterial analysis showed that highest bacteria density (34.5–48.5 CFU by Nutrient Agar) was detected from air samples collected from Liaquat Bagh, followed by Mareer (up to 30.5 CFU on Nutrient Agar and 176 CFU of E. coli on Eosin Methylene Blue Agar in the evening). Saddar had the lower number of bacteria in each medium (16–26 CFU on Nutrient Agar, 1.5–3.5 CFU of E. coli on Eosin Methylene Blue Agar). The surface contamination level of Saddar was highest in the morning (350 CFU total bacteria on Nutrient Agar), whereas Mareer showed elevated contamination (79.5 CFU coliforms on MacConkey Agar, 1 CFU Salmonella/Shigella on SS Agar, and 5.5 CFU of E. coli on Eosin Methylene Blue Agar), while Liaquat Bagh had moderate levels (24 CFU total bacteria with 0.5 CFU of E. coli). Among these, Mareer station was the most polluted station for surface samples in all the three stations. Air samples were highly polluted in Liaquat Bagh and significant surface loads were also found for Saddar, even though it had moderate air contaminated samples. Worker and passengers’ exposure varied by terminal and medium. Low Salmonella/Shigella Agar exposure (0–1.19 CFU/m3) was seen at P1 and P2, with no exposure at P3. All terminals showed stable low values on MacConkey Agar (0.14–7.78 CFU/ m3), consistent with coliform bacteria. The Nutrient Agar showed significant exposures, with P1 peaking in the evenings (4.79 CFU/ m3 workers, 70.7 CFU/m³ passengers), P2 peaking in the mornings (9.13 CFU/m3 workers, 91.6 CFU/m³ passengers), and P3 having the highest overall exposures (10.32–14.5 CFU/m3 workers, 83.8– 130.9 CFU/m³ passengers). Eosin Methylene Blue Agar exposures were low to moderate overall, with maximum values at Mareer in the evening (52.7 CFU/m3 for workers and passengers, indicating high E. coli contamination). Nutrient Agar indicated the highest bacterial burden, especially at Liaquat Bagh for air samples. This study underscored concerning levels of bacterial contamination in public transportation in the three (03) metro bus terminals of Rawalpindi, highlighting the prevalence of Gram-positive bacteria along with coliform bacteria, Salmonella/Shigella, and E. coli on different cultures. Implementing appropriate hygiene protocols and ensuring consistent sanitation are crucial for minimizing microbiological hazards and preventing the transmission of community-acquired illnesses.