1. Don’t Swim in the Pool Patrick Racine SiddarthSanthebennur
2. Background Several cases of skin rash infections reported at Hotel A in Bangor, Maine Feb. 18-27, 2000 Infections related to low chlorine levels in the pool and hot tub >1.0 mg/L, less than state required 1-3 mg/L Sample of unknown pathogen taken from draining ear of 6 year old child and the pool filter
3. Patient History 9 patients infected Had rash for 7 days (or less) or an outer ear infection All had spent time in either the pool or hot tub 7 spent time in both
5. Possible Culprits Originally there were 6 potential bacteria that could have caused the infections: Escherichia coli Pseudomonas aeruginosa Salmonella enterica Staphylococcus aureus Streptococcus pyogenes Haemophilusinfluenzae
6. Gram Stain A Gram stain differentiates bacteria based upon properties of their cell walls using a crystal violet stain Separated into 2 categories: Gram-positive (+) (dark blue/violet) Gram-negative (-) (red/pink) E. coli and S. aureus were Gram stained along with unknown bacteria for comparative reasons
7. Results of Gram Stain Gram stain showed that the unknown bacteria is Gram-negative Due to its red/pink color This eliminates 2 bacteria from being considered the cause of the outbreak Staphylococcus aureus Streptococcus pyogenes Both are Gram positive
8. Differential/Selective Media Two types of growth media used to inhibit or isolate growth of a microorganism Differential: Different microorganisms grown on the same media; distinguished by how each organism reacts to specific dyes and chemicals placed on media Selective: Allows growth of specific organism, inhibits others
9. Type of Growth Media Used Two options: MacConkey’s Agar Mannitol Salt Agar Because the suspect bacteria is Gram-negative, the best option was the MacConkey Agar Allows for growth of Gram-negative bacteria and inhibits the growth of most Gram-positive bacteria
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11. Pseudomonas aeruginosa Rod-shaped Aerobic respiration Due to production of arginine, undergoes anaerobic respiration as well Found in various environments including soil, water and hospitals Most abundant organism on Earth Opportunistic Rarely infects healthy individuals Prefers individuals with unhealthy immune systems Resistant to many antibiotics
14. Escherichia coli and Salmonella enterica both cause infection of the digestive system
15. Although Staphylococcus aureusdoes cause various skin infections, including folliculitis, it does not cause the outer ear infection that is also associated with the culprit bacteria
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17. Antimicrobial Susceptibility Test The antibiotic that creates the largest zone of inhibition would be considered the most effective.
