BMS524 Case study: Epidemiology of an outbreak of nosocomial infection
The surgical unit in a large and busy teaching hospital has experienced an infection control problem. 48h postoperatively two patients on one ward and one patient on a different ward became pyrexial (elevated body temperature) with signs of a local wound infection. Swabs were taken of the wounds and sent for microscopic analysis (see above) and microbiological investigation. A Gram stain of the wound swab revealed the presence of clusters of Gram positive cocci and these were also identified on the growth media.
Answer each of the following questions separately. A word count guide is provided. Do not exceed the upper limit. Use references as required, they do not contribute to the word count but a properly formatted reference section must also be included at the end.
Q1 What species of Gram positive organisms are likely to be isolated from wound infections? Explain your reasoning. Examples of gram positive organisms are staphylococcus aureus (staph.aureus), enterococci, micrococci and methicillin resistant …show more content…
(Foster T 1996) Coagulase is a traditional marker for identifying Staphylococcus aureus from other types of staphylococci. (Foster T 1996) The coagulase test detects the amount of coagulase. A colony of this organism is mixed with plasma and incubated at 37°C for four hours resulting in a clot formation. This indicates a coagulase positive Staphylococcus aureus. Staphylococcus aureus can also express a deoxyribonuclease (DNase). (Foster T 1996) A DNase test is commonly used to differentiate Staphylococcus aureus from other Staphylococci. An isolate of this organism is placed onto an agar plate containing DNA and a white colony is formed. Clear areas are formed around the colonies indicating hydrolysis of the DNA showing Staphylococcus aureus. (Struther JK et al
The surgical unit in a large and busy teaching hospital has experienced an infection control problem. 48h postoperatively two patients on one ward and one patient on a different ward became pyrexial (elevated body temperature) with signs of a local wound infection. Swabs were taken of the wounds and sent for microscopic analysis (see above) and microbiological investigation. A Gram stain of the wound swab revealed the presence of clusters of Gram positive cocci and these were also identified on the growth media.
Answer each of the following questions separately. A word count guide is provided. Do not exceed the upper limit. Use references as required, they do not contribute to the word count but a properly formatted reference section must also be included at the end.
Q1 What species of Gram positive organisms are likely to be isolated from wound infections? Explain your reasoning. Examples of gram positive organisms are staphylococcus aureus (staph.aureus), enterococci, micrococci and methicillin resistant …show more content…
(Foster T 1996) Coagulase is a traditional marker for identifying Staphylococcus aureus from other types of staphylococci. (Foster T 1996) The coagulase test detects the amount of coagulase. A colony of this organism is mixed with plasma and incubated at 37°C for four hours resulting in a clot formation. This indicates a coagulase positive Staphylococcus aureus. Staphylococcus aureus can also express a deoxyribonuclease (DNase). (Foster T 1996) A DNase test is commonly used to differentiate Staphylococcus aureus from other Staphylococci. An isolate of this organism is placed onto an agar plate containing DNA and a white colony is formed. Clear areas are formed around the colonies indicating hydrolysis of the DNA showing Staphylococcus aureus. (Struther JK et al