Detection of Klebsiella pneumoniae & Listeria monocytogenes and analysis of their antibiotic resistance in Bangladeshi homemade cosmetics

Abstract

In Bangladesh, homemade organic cosmetics such as whitening night creams, whitening serums, soaps, face packs and scrubs are in high demand, particularly among women. Many of these products are marketed as pure organic and chemical-free. However, the potential risk of bacterial contamination remains largely unexplored. This study aimed to analyze the pathogenic bacterial load in Bangladeshi homemade cosmetics targeting 10 clinically significant bacteria, including Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus spp., Escherichia coli, Salmonella spp., Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter baumannii. As part of this group project, my individual focus was on Klebsiella pneumoniae and Listeria monocytogenes, to evaluate their prevalence and potential public health implications. A total of 22 samples were collected from online sellers who claim to sell organic homemade cosmetics. For bacterial load determination, samples were enriched in Modified Letheen Broth and plated on Modified Letheen Agar for CFU counts. Isolation and detection of Klebsiella pneumoniae were performed by using KPC agar followed by PCR confirmation. Moreover, Listeria monocytogenes was detected using Listeria Selective Oxford Agar followed by PCR confirmation as well. Antibiotic susceptibility testing (AST) was performed using the Kirby Bauer disk diffusion method against a panel of 13 antibiotics with four additional antibiotics included- Vancomycin and Linezolid for Gram-positive bacteria and Colistin and Aztreonam for Gram-negative bacteria. Out of the 22 cosmetic products tested, 20 (90.09%) were positive for Klebsiella pneumonia and 2 (9.1%) were positive for Listeria monocytogenes. For Klebsiella pneumoniae, AST performed on 22 isolates that revealed high resistance to Ampicillin (92.3%), Azithromycin (84.6%), and Ciprofloxacin (76.9%) while resistance to other antibiotics ranged between 7.7% and 23.1%. However, Listeria monocytogenes isolates displayed mixed susceptibility patterns: one isolate was largely sensitive, while the other showed resistance to several key antibiotics including Linezolid, Vancomycin, Ampicillin and Daptomycin. This study highlights the significant presence of pathogenic bacteria in Bangladeshi homemade cosmetic products. The high contamination rates and concerning resistance profiles are alarming for public health, emphasizing the urgent need for microbiological safety monitoring and consumer awareness.