Question

A 33-year-old pregnant woman, Stephanie D., reported to the emergency department with premature labor. She stated that she felt a little "under the weather" for the past week with a slight fever, some back pain, and headache. She explained that she began to feel "some occasional crampiness" over the previous 24 hours but did not think this could be contractions because she was only 30 weeks pregnant. She was surprised with membrane rupture about 2 hours ago and had experienced an increase in the frequency of the contractions, which were now approximately 3 minutes apart. She was taken to the delivery room and eventually delivered a 950-gram boy. The infant was in severe respiratory distress and was intubated immediately. Gross examination of the placenta revealed ischemic areas, and samples of the tissue were sent to pathology and microbiology. Cerebrospinal fluid (CSF) and blood cultures from the baby were also collected. Results: Direct Gram's stain of the CSF revealed many neutrophils and short gram-positive coccobacilli. The pathology examination showed multiple abscesses approximately 1 to 3 cm in diameter. Upon microscopic examination, the abscesses revealed neutrophilic infiltration and aggregates of necrotic villi. Placental tissue, CSF, and blood cultures were all positive within 24 hours. The colonies on the blood-agar plate (BAP) were small, translucent, and gray, with a very narrow beta-hemolysis zone. (The microbiologist did not even notice the hemolysis until she had removed a colony for further testing.) Additional testing included a positive catalase test, an umbrella-like zone of growth in motility media at 22Â°C, growth at 4Â°C, a positive esculin hydrolysis test, and a negative H2S reaction. 4. Why is the ability of this organism to grow at 4Â°C important to its pathogenicity? 5. What measures should be taken to avoid infection with this organism? 6. Pregnant women are predisposed to infection with this organism. What other groups are at high risk? 7. What are some of the virulence factors this organism possesses?

A 33-year-old pregnant woman, Stephanie D., reported to the emergency department with premature labor. She stated that she felt a little "under the weather" for the past week with a slight fever, some back pain, and headache. She explained that she began to feel "some occasional crampiness" over the previous 24 hours but did not think this could be contractions because she was only 30 weeks pregnant. She was surprised with membrane rupture about 2 hours ago and had experienced an increase in the frequency of the contractions, which were now approximately 3 minutes apart. She was taken to the delivery room and eventually delivered a 950-gram boy. The infant was in severe respiratory distress and was intubated immediately. Gross examination of the placenta revealed ischemic areas, and samples of the tissue were sent to pathology and microbiology. Cerebrospinal fluid (CSF) and blood cultures from the baby were also collected.

Results:
Direct Gram's stain of the CSF revealed many neutrophils and short gram-positive coccobacilli. The pathology examination showed multiple abscesses approximately 1 to 3 cm in diameter. Upon microscopic examination, the abscesses revealed neutrophilic infiltration and aggregates of necrotic villi. Placental tissue, CSF, and blood cultures were all positive within 24 hours. The colonies on the blood-agar plate (BAP) were small, translucent, and gray, with a very narrow beta-hemolysis zone. (The microbiologist did not even notice the hemolysis until she had removed a colony for further testing.) Additional testing included a positive catalase test, an umbrella-like zone of growth in motility media at 22Â°C, growth at 4Â°C, a positive esculin hydrolysis test, and a negative H2S reaction.

4. Why is the ability of this organism to grow at 4Â°C important to its pathogenicity?
5. What measures should be taken to avoid infection with this organism?
6. Pregnant women are predisposed to infection with this organism. What other groups are at high risk?
7. What are some of the virulence factors this organism possesses?

Added by Thomas C.

Question

Please give Ace some feedback