Question

A 40-year-old male called 911 stating that he was having difficulty breathing and felt too nauseous to drive himself to the hospital. He said he had type I diabetes and had not been able to afford insulin on a consistent basis, especially over the past week, since he lost his job. Fortunately, the emergency medical team promptly got to the patient and took him to the hospital. His blood work revealed an exceedingly high blood glucose level, a finding consistent with the fact that the body relies on insulin to get glucose into cells. The patient was diagnosed as suffering from ketoacidosis. This is a metabolic state in which the body perceives that it is starving for glucose and so switches to mainly catabolizing fats. In ketoacidosis, ketones, which are by-products of fat catabolism, rapidly build up in the body and dangerously lower the blood’s pH level. After stabilizing the patient, a thorough physical examination was performed.

Upon physical examination, the physician noticed the man had an infected ulcer on his foot. A bacterial specimen was collected and analysis showed Gram-positive rods that form endospores. The doctor said it was fortunate that the man sought medical assistance, because he could have gone into a coma and died from ketoacidosis. Also, he told the patient that if ketoacidosis had not killed him, the foot wound could have. The ulcer was infected with an anaerobic bacterium, Clostridium perfringens, which causes gas gangrene.

The patient stated that he often had slow-healing sores on his feet and asked if it was something to be concerned about. The doctor explained that people who have diabetes and do not consistently regulate their blood glucose often suffer from a number of complications, including circulatory system vessel damage. When blood vessels are damaged, blood delivery to the tissues is decreased, which can affect healing. This pathology is particularly common in the extremities, and especially the feet. Follow-up care for all wounds is important to prevent future infections with dangerous bacteria like C. perfringens. Fortunately the patient’s infection was localized and readily responded to basic wound care and a regimen of clindamycin and penicillin.

Would the following biochemical tests be positive or negative for Clostridium perfringens? View Available Hint(s) Reset Help positive 1. Fermentation test: negative 2. Catalase test: 3. Durham tube 4. Gram stain: 5. Oxidase test:

Answer 1

Answer:

Fermentation Test: Positive.

Catalase Test: Negative.

Durham Tube: Positive.

Gram Stain: Positive.

Oxidase Test: Negative.

Explanation:

From the medical examination it was very clear that the organism is a gram positive, anaerobic microbes which also produces a gas known as gangrene.

Fermentation takes place during anaerobic condition, hence our microbe is fermentation positive. Catalase enzyme is produced in organism which is exposed to oxygen, hence it is catalase negative because our organism is an anaerobe (not exposed to oxygen). Durham tube experiment is used to detect the production of gas (such as gangrene) by microbes, hence our microbes durham tube positive. It is already mentioned in the paragraph that our bacteria is a gram positive bacteria. In an anaerobic organism oxygen can not be used as an electron acceptor, hence oxidase negative. Only organism which uses oxygen as the electron acceptor are considered as oxidase positive.