1.  In conclusion, bacteria present in cigarettes can be transferred into mainstream smoke, presenting a novel means for direct bacterial exposure among smokers linked to elevated rates of respiratory infections.  What is the effect of combustion and the smoking process on the bacteria present in commercially available cigarettes? Introduction  Currently, there are over 1.2 billion smokers in the world (Chaloupka, 1999). More than 15 billion cigarettes are sold daily; around 10 million every minute.  Smoking is the primary cause of preventable disease and death, killing one in ten adults, or 4.9 million individuals annually. A smoker’s lifespan is cut down by five minutes or more for each cigarette that is smoked (World Health Organization 2002). Secondhand smoke is responsible for 53,000 additional deaths per annum (Schick and Glantz 2005).  Smoking is a leading risk factor in heart disease, stroke, cancers (including those of the lungs, larynx, esophagus, mouth, bladder, cervix, pancreas, and kidneys), chronic obstructive pulmonary disease, atherosclerosis, asthma, emphysema, chronic bronchitis, and acute respiratory infections (Aronson et al. 1982, World Health Organization 2002, and Yanbaeva et al. 2007).  Cigarette smoke is known to be a toxic mixture of over 4,000 chemicals harmful to humans (World Health Organization 2002). Exposure to these compounds alters respiratory physiology, leads to immunosuppression, and enhances binding of pathogens to epithelial cells (Ahmer et al. 1999, Pauly et al. 2008).  Acute respiratory tract infections (ARTIs) are the most common complaint leading individuals to seek medical attention in the United States. While it has been noted that smokers have higher rates of ARTIs than the general populace, the mechanism behind this trend is not well described (Aronson et al. 1982).  Bacterial growth was observed from tobacco flakes and micro-particulate matter in 90% of culture trials (Pauly et al. 2008).  16S rRNA-based taxonomic sequencing identified fifteen classes of bacteria in four major international brands of cigarettes (Sapkota et al. 2010). Medically relevant pathogens included Acinetobacter, Bacillus, Clostridium, Escherichia, Pseudomonas, Serratia, and Staphylococcus.  There have been no published studies examining the bacterial content of cigarette smoke. The Fate of Bacteria Found in Cigarettes Through the Smoking Process: A Novel Source of Direct Bacterial Exposure David Gaiteri, Department of Biological Sciences, York College of Pennsylvania http://www.affordablecebu.com/_ld/6/s52024320.jpg Methods Research Objective: Results Tobacco Cultures  Bacterial growth observed in all tobacco flake and dilution trials Marlboro Preliminary Trials Smoke Sampling Trials  Bacteria extracted from the mainstream smoke of each cigarette brand.  Bacterial growth in one-quarter (25%) of all trials. Discussion  Tobacco flakes and particulate matter found on cigarette butts could easily be transferred to the respiratory tract of smokers.  Air drawn through cigarettes, without combustion is sufficient to transfer bacteria from the tobacco to the cigarette butts and into the mainstream air flow.  Bacteria can be transferred through mainstream cigarette smoke.  Survival of bacteria present in cigarette smoke is related to the relative concentration of toxic compounds per unit exposed surface area.  Bacteria in mainstream smoke can survive the combustion and smoking process.  The implications of these findings raise questions regarding additional consequences of secondhand and thirdhand smoke exposure. Literature Cited Acknowledgements I would like to thank my research mentor Dr. David Singleton and the Biological Science Department at York College of Pennsylvania.  Determine whether viable bacteria present on the tobacco of cigarettes are transferred through mainstream smoke, and could represent a potential source of direct bacterial exposure to individuals who smoke. http://theinspirationroom.com/daily/print/2009/4/adsef_smoking_lungs.jpg Figure 1. Tobacco flakes on the cigarette butts of a newly opened Marlboro carton. Figure 2. Bacterial growth from tobacco flakes and particulate matter collected from the cigarettes butts pictured in Figure 1. Figure 3. Percentage of successful bacterial cultures observed in preliminary Marlboro trials (n=10/condition). Combustion Trials: Bacterial growth on cigarette butts (100%), but no growth on membrane filters. Vacuum Trials: Bacterial growth on cigarette butts (60%) and membrane filters (20%). Static Trials: No bacterial growth on cigarette butts or membrane filters. Figure 4. Percentage of successful bacterial extractions in puff-sampling smoking trials (n=7/brand). Bacteria were extracted from Marlboro (43%), Camel (14%), Newport (14%), and Pall Mall (29%) smoke samples Figure 5. Bacterial samples cultured from mainstream cigarette smoke.