An epidemiologic study is conducted after a sudden increase in the rate of severe postoperative infections in a rural hospital. It is determined that all the patients who developed the infection were operated on with surgical instruments sterilized by a specific autoclave machine. The machine was found to be inadequately sterilizing the equipment due to a malfunction limiting the temperature to 100 C (212 F) during the 15 minute cycle. These patients most likely developed infection from which of the following bacteria?

Question

An epidemiologic study is conducted after a sudden increase in the rate of severe postoperative infections in a rural hospital.  It is determined that all the patients who developed the infection were operated on with surgical instruments sterilized by a specific autoclave machine.  The machine was found to be inadequately sterilizing the equipment due to a malfunction limiting the temperature to 100 C (212 F) during the 15 minute cycle.  These patients most likely developed infection from which of the following bacteria?

Quizplus · Accepted Answer

Autoclave machines are pressure cookers that use heated steam at temperatures of 134 C (273.2 F) to rapidly destroy pathogenic bacteria, fungi, viruses, and spores. Lower temperatures are often associated with inadequate sterilization due to the presence of spore-forming bacteria, which can survive at temperatures past the boiling point of water (100 C [212 F]). Bacterial spores are often found in soil and water and are resistant to chemical disinfectants, irradiation, desiccation, and temperatures as high as 120 C (248 F). Bacillus (eg, Bacillus anthracis) and Clostridium (eg, Clostridium perfringens, C botulinum) species are among the most common spore-forming pathogenic bacteria. (Choices A, C, D, and E) These organisms do not form spores; vegetative bacteria are usually destroyed by temperatures >70 C (158 F). Educational objective: Spore-forming bacteria can survive boiling temperatures. Bacillus and Clostridium species are common pathogenic spore-forming bacteria. __________ References: Control of bacterial spores. (http://www.ncbi.nlm.nih.gov/pubmed/10885113)

An Epidemiologic Study Is Conducted After a Sudden Increase in the Rate