Humans are aerobic organisms. If so why do we worry about being by an anaerobic
ID: 85035 • Letter: H
Question
Humans are aerobic organisms. If so why do we worry about being by an anaerobic organism? A swab for culture is received from a doctor's office. The stuff forgot to mention the source from where the swab was taken and the clinic was closed for next few days. When different selective/differential media may be helpful to you 10 identify the organism. Explain very briefly your rationale for using the particular media? A gar and gelatin are used as a solidifying agent for media. Why is gelatin less suitable than the agar? A is performed on isolated colony on a blood agar plane and bubbles appear. The repeated on another isolated colony form the same plate. This time there are no bubbles. How can you explain the difference in the results? You are given a tube of contaminated water. The number of bacteria in the tube is 100 many to count. You prepare a dilutions in 5 tubes, so that tube has 1:10 dilution, tube #2 has 1:100 dilution, tube #3 has 1:1000 dilution, tube #4 has 1:10,000 dilution and tube #5 has 1:100,000 dilution. The second tube has 210 cells and the third tube has 26. What is the number of per ml in the original sample? Several individuals have food poisoning due to Salmonella from a common source. several individuals went to the local emergency rooms of the hospital complaining of similar. How could you determine and be sure that these individuals have the same infection? Distinguish between alpha-and beta-hemolysis? How would you differentiate between and ? Why are females more to UTI than males? What would be the effect of a urine sample being left at room temperature overnight before transported to the laboratory for culture?Explanation / Answer
1. ANS: Most of the human normal flora is composed of anaerobic bacteria suggests that anaerobic infections might be of medical concern. anaerobic infections can occur in a variety of body sites and involve many different genera. Most of the normal anaerobic flora are not overtly pathogenic; rather, they are considered to be opportunistic. That is, if given the opportunity, they can inflict us.
Ex: trauma, injury or surgery.
A loss of natural barriers that introduce these bacteria into normally sterile body sites may result in infection.
Ex: 1. intraabdominal infections
2. pulmonary infections
3. pelvic infections
2. ANS: I would put the swab in about a 1 mL sterile saline to make a homogenized solution and streak to blood agar (most non-fastidious bugs will grow on this), chocolate agar (for those most fussy bugs), McConkey agar (see if any gram negs grow) and inoculate thioglycolate broth (will grow both aerobic and anaerobic bugs). This should cover you basics for micro cultures. You can always streak to more differential media from the thio broth. Just make sure its not a swab for viral stuff, but that should be obvious by the type of swab submitted.
3. ANS: Both of these are solid at room temperature; however, they melt at different temperatures. Gelatin melts at a relatively low temperature-less than 35 celsius (think about Jello melting in the summer heat). Agar melts at 85 celsius. As such, when gelatin is incubated at the normal temperature for bacterial growth (37 celsius), it will likely melt or at least not be as firm (and the bacteria could end up in a soupy mess of melted gelatin), while agar will remain solid. Also, bacteria can digest gelatin more readily than agar.
4. ANS: When the isolate was tested directly on the plate, the peroxide reacted with the blood in the agar to produce bubbles (think about putting peroxide on a cut). When tested on a clean slide, the peroxide only had the bacteria to react with the isolate were catalase negative, so no bubbles appeared.
5. ANS: The second tube has 210 cells and the third tube has 26 colonies." - We need to know the volume that was taken from the tubes to be able to calculate the answer.
6. ANS: Bacterial cultures could be taken from each patient, and then be tested using antigens in the lab. If they are the same strain of Salmonella they will all react with the same antigen.
Please remind this note: Answering to many questions is against to chegg rule, so I am answering 1- 6 questions.
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