Essay on Two Ampicillin Resistant Bacteria Often Present

830 Words Feb 23rd, 2016 4 Pages
1) Two ampicillin resistant bacteria often present in salad;
Aeromonas spp. Gram Negative, Bacillus Pseudomonas spp. Gram Negative, Bacillus Oxidase Positive Oxidase Positive Fermentative Oxidative
The results found in table 2, match the specification for Aeromonas spp being gram negative, a bacillus fermentative and oxidase positive. However to come up with a specific species further tests such as a Møeller decarboxylase and dihydrolase reactions to help narrow down the identification by the presence of absence of enzymes, but Aeromonas spp. are difficult to distinguish between due to a lack of differential biochemical characteristics (Abbott, Cheung, & Janda, 2003).

2) NA plate: (151x10⁴)/0.1= 15,100,000 bacteria per 10.021g of salad
15,100,000/10.021=1,506,836 bacteria per 1g of salad. AMP plate: (63.5x10⁴)/0.1 =6,350,000 ampicillin resistant bacteria per 10.021g of salad
6,350,000/10.021=633,669 ampicillin resistant bacteria per 1g of salad (633,669/1,506,836) x100=42.1% of bacteria present in 1g of ready to eat salad are ampicillin resistant.
3) Aeromonads apart from Aeromonas trota are resistant to ampicillin, therefore this antibiotic is often added to agar and mediums to act as a selective agent (Huddleston, Zak, & Jeter, 2007). Normally…

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