Based on the following journal article related to bacterial growth and cultures,

Question

Based on the following journal article related to bacterial growth and cultures, please answer the following discussion-type question accordingly. Please support any information you wish to provide and be as short & concise as possible. If answer is in complete sentences & well written , I will rate. Ty!* The URL of article has been provided for further reference.

http://www.sciencedirect.com/science/article/pii/S2405471215000022

Recently, an article was published that identified the types of bacteria that can be found on the NY subway. Although the majority were nonpathogenic, several pathogenic bacteria were identified such as Staphylococcus aureus, Bacillus anthracis, Yersinia pestis and E. coli. Some of the bacteria were identified solely on the presence of their DNA and were not able to be grown in culture. Please discuss whether or not the riders of the subway are at risk for infection (or intoxication). Include discussion on a specific pathogenic microbe from the paper and the risk based on portals of entry, number of invading organisms (LD50), ability to produce toxins, etc. http://www.sciencedirect.com/science/article/pi/S2405471215000022

Explanation / Answer

Although the report clearly states that "No conclusive evidence suggests that the factors and sequences that drive pathogenicity were present." Viable bacteria, that could be grown on culture plates were found in the subway stations, making the riders vulnerable to a number of infections from the pathogens. The bacteria were introduced to four different types of LB agar plates- one being the control and three with kanamycin, chloramphenicol, and ampicillin. It was found that all plates (18/18) had viable bacteria that could be cultured on standard agar plates.

i) Stations with detectable levels of S. aureus underwent an examination for the presence of the mecA gene. mecA gene is associated with methicillin-resistant Staphylococcus aureus (MRSA) and infections by resistant species of the bacterium A 32× coverage of the mecA gene was observed in some stations but a wide range of coverage was found to be present at the stations (0.2×–32× coverage of the gene). The pathogen specifically enters through the route of skin and causes corresponding infections.

ii) pMT1 plasmid of Y. pestis, which is a known virulence factor that can promote deep tissue invasion and acute infection symptoms, was also examined. A similarly wide range of coverage from different samples (0.6×–31×) across the pMT1 plasmid, which is considered a virulence element for Y. pestis. Although the murine toxin (yMT) gene itself was not covered by any reads.

ii) However, there is almost negligible possibility of any rider to have to be infected by Anthrax, due to a subway ride. B. anthracis has shown a very low coverage of its virulence plasmids, pXO1 and pXO2. No evidence of the plcR SNP, which is often used as a defining feature of anthrax, was found.

Although some classes of bacteria, such as the GI-tract and Enterococcus faecium, have been found abundantly across the subway, these are actually lower than expected from known annotations, whereas the skin bacteria represent a strong enrichment.

The LD 50 values of Skin infecting bacteria have been higher than pathogens causing infections in other areas of the body.

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