Bacteriological comparison of oral swab samples collected from conventional cigarette smokers and e-cigarette smokers

Abstract

This study explored the impact of Conventional Cigarette Smoker (CCS), Electronic Cigarette Smoker (ECS), and Conventional Cigarette Smoker+Electronic Cigarette Smoker (CCS+ECS) use on the oral microbiome in a population from Bangladesh, where clinical research on e-cigarette users remains scarce. Oral swab samples were collected from a total of 40 participants, including 10 e-cigarette users, 10 conventional cigarette smokers, 10 dual (E-Cigarette and Conventional Cigarette) users, and 10 non-smokers. Samples were cultured and Gram stained to identify the presence of Gram-positive and Gram-negative bacteria. In terms of culture-based study, Nutrient Agar (NA) medium and Blood Agar Plates (BAP) being used. The average total aerobic count on NA medium showed difference among the groups. The highest CFU/mL count were observed on CCS group (4.8 × 10⁹ CFU/ml), followed by NS group (4.6 × 10⁹ CFU/ml), CCS + ECS group (3.9 × 10⁹ CFU/ml) and ECS (2.8 × 10⁹ CFU/ml). In contrast, Blood Agar Plates (BAP), being enriched and capable of revealing hemolytic activity, provided an insight into bacteria that may be opportunistic or pathogenic whereas ECS showed the highest overall bacterial load, with BAP counts reaching 1.5 × 10⁷ CFU/mL. CCS and CCS+ECS had comparable levels, ranging from 6.0 to 6.5 × 10⁶ CFU/mL, while NS showed 7.7 × 10⁶ CFU/mL. A significant difference between the ECS group, CCS group (p = 0.02) and CCS + ECS group (p = 0.02), indicating that e-cigarette users may harbor a greater abundance of fastidious bacterial species compared to other groups. It was hypothesized that smoking and vaping would disturb the natural oral microbial balance, increasing suspected harmful bacteria. In this case, we did the Gram-staining method and the findings revealed that CCS and ECS exhibited a higher presence of Gram-negative bacteria compared to other groups. CCS displayed a dominance of Gram-positive bacteria, suggesting a unique microbial response to tobacco exposure. ECS showed a slightly decreased Gram-negative count compared to NS, although the NS and CCS+ECS shared similar microbial profiles overall. Despite noticeable changes in bacterial composition, overall microbial diversity remained relatively stable, implying that host-related factors like genetics and hygiene may also have played a role. These results highlighted the compounded risks of e-cigarette and conventional cigarette use, questioning the idea of vaping as a more secure substitute to smoking. The pressing need for preventive health interventions and continued investigation of the long-term oral health outcomes of smoking and vaping was highlighted by the research, particularly in emerging markets such as Bangladesh.