Question

Case study:

Denise is a 45-year-old American female who has been admitted to the medical ward after having symptoms of food poisoning and skin rash. Her temperature has been over 38°C and she has been complaining of diarrhea and vomiting. Denise also presented with nasty looking skin rash on her upper and lower extremities. According to Denise, the skin rash has started since she swam in the Owens Lake (in California) 3 days ago. She stated that the rash started as small “red bumps” but started to get worse, deeper and more painful around a cut skin that she had sustained a week ago. She admits that she is not sure whether her current health conditions were caused by her swimming in the lake or because of the takeaway food that she also had on the same day. When Denise was asked about the takeaway food, she recalled that she thought the chicken was not fully cooked when she started eating it. Denise had a skin swab taken and a stool sample was sent for culture and sensitivity. The stool sample analysis confirmed food poisoning with Salmonella enterica and the skin swap results revealed Vibrio Cholerae skin infection

Q1

Discuss one strategy that Vibrio Cholerae uses to survive its unique environmental condition.?

Q2

Based on the factors that affect microbial growth, classify the category of bacteria that Salmonella enterica belongs to.?

Answer 1

1. Vibrio Cholerae the causative agent of the disease condition Cholera. The main source of infection is contaminated food and water. The organism mainly survives in areas with poor sanitation and contaminated water supplies. This accounts for annual epidemic outbreaks in several regions worldwide (America, Asia and Africa) because of the capability of Vibrio Cholerae to survive in aquatic environment around the year. In a constantly changing environment in order to survive the organism requires the ability to overcome the physiochemical stresses like nutrient starvation. In such conditions these organisms exists in a neutral state with a slow growth and less metabolic activity. Changes in the environment may also cause changes to their cell structure as well as functions. These changes may occur either through genetic changes or phenotypic adaptation. Phenotypic adaptation is the process by which an organism alters it body in order to cope up with and survive mutations or genetic changes.

For example studies proves that in nutrient starvation the cells of Vibrio Cholerae cholerae changed to coccoid structure loosing its volume to about 90% in a month duration, the number of cells increased, loose their granules and inclusion bodies as well as lost the integrity of their outer and inner membranes and only the remnants of those parts were left. Also the nuclear region was compressed to the center of the cell surrounded by a dense cytoplasm . They were able to form extended and convoluted structures from the cell wall that are pulled away from the cell membrane. This reflects the strategies of V. Cholerae to survive under nutrient deprivation in adverse environmental conditions.

2. Salmonella enterica is a gram negative bacteria belonging to the genus salmonella. Factors that affect the microbial growth can be classified into physical and chemical factors mainly. Physical factors include temperature, pH, pressure (osmotic and hydrostatic) and radiation. Chemical factors includes concentration of oxygen, carbon dioxide, nitrogen, Sulphur etc.

Bacteria can be classified as phototrophs or chemotrophs based on the source of their energy.  Salmonella enterica are chemotrophs that depends on oxidation and reduction reactions using organic sources for their energy.

Based on their oxygen requirement bacteria can be classified as obligate aerobes, obligate anaerobes, aerotolerant anaerobes, facultative anaerobes and microaerophiles. Salmonella enterica are facultative anaerobes that uses oxygen when it is available for energy (ATP) production and uses anaerobic methods like fermentation or other electron acceptors for energy production when Oxygen is not available for energy production.

Based on their temperature requirement bacteria are categorized as psychrophiles, mesophiles, thermophiles, or hyperthermophiles. Salmonella enterica is a mesophilic organism which requires a moderate temperature (neither too hot or cold) for its growth.