microbiology situations Questions and Answers Graded A+

microbiology situations Questions and Answers Graded A+ A previously healthy young woman was admitted to the intensive care unit with high fever, hypotension, nausea, vomiting, disseminated sunburn-like rash, generalized muscle aches and imminent cardiac and renal failure. Her last menstrual period was about 5 days ago. A blood sample reveals gram-positive cocci arranged in clusters that produce beta-hemolytic catalase-positive colonies on sheep blood agar. TSS Staphylococcus aureus A 10-year-old girl presents to her primary care physician with a severe sore throat, headache, nausea, and abdominal pain. Examination shows the back of her throat is covered with white pus-filled nodules. Culture of the exudate on blood agar produces beta-hemolytic colonies composed of gram-positive cocci in chains. Strep throat Streptococcus pyogenes A 15-year-old boy presents at the emergency room with a 24-hour history of painful urination. He has discharge in his underwear and on the tip of his penis. Urine appears clear, although many white blood cells are present. The young man gives a history of heterosexual activity with five partners over the past 6 months. All his partners were "clean" he said. A Gram stain of the discharge reveals gram-negative diplococci. Neisseria gonorrhea A 20-year-old normally healthy woman with a history of urinary tract infection (UTI) presents to the emergency room with nausea (no vomiting), left flank pain, fever, chills, and foul-smelling urine. Urinalysis shows large numbers of white and red blood cells per high power field accompanied by large numbers of motile, gram-negative rods. Escherichia coli A 9-year-old boy with a 2-day history of diarrhea presents to the emergency room with blood in his stools and increased stool volume. He has vomited once. The boy went to a cookout 5 days earlier and ate a hamburger that was still "pink" inside. On examination he is well, apart from some dehydration. Coliform bacteria exhibiting a metallic green sheen on EMB agar were identified. Escherichia coli (carries exotoxin in this strain) A male patient returned last weekend from a vacation in Kenya where he went on safari with his wife. Rodents and fleas were present at the campsite. He presents with fever, chills, headache, nausea, and weakness. On examination he is found to have an enlarged lymph node in his groin, which is tender. A sample of blood taken from the patient shows a capsulated, gram-negative rod present in the bloodstream. The physician begins treatment of the patient with chloramphenicol immediately. Bubonic plague; Yersinia pestis A 25-year-old worker felt dizzy and confused and was experiencing some double vision. Her coworker became concerned and drove her home. That night the patient woke at 2 a.m. having difficulty in swallowing and immediately phoned for an ambulance. On admission, she appeared weak and drowsy. The last meal she ingested had been at lunch of the previous day and consisted of a cheese and bologna sandwich with home canned salsa. The patient's condition subsequently worsened, and she required 6 weeks of supportive care, including 5 weeks on a ventilator. No bacterial species were isolated from her stool samples using standard techniques. Why? Clostridium botulinum; ingested neurotoxin A 65-year-old alcoholic was taken to the emergency room with severe necrotic, blackened areas on both feet and several draining ulcers on his heels and toes. He was stuporous. During that evening he had a seizure. By the end of the night he had developed increasing rigor and respiratory distress and was unresponsive. His neck was stiff and hyperextended and his teeth clenched in a grimace. Specific therapy and supportive care led to his full recovery. Clostridium tetani; neurotoxin = spastic paralysis Robert, a 50-year-old HIV-positive male, presents to his primary care physician with a 3-month history of fevers, night sweats, productive cough , and an 11-kilogram weight loss. He is not an injection drug user or homosexual, but admits to numerous heterosexual encounters. Acid-fast stains of his sputum are positive, and the bacteria were isolated from the right middle lobe of his lung. Mycobacterium tuberculosis A 5-week-old baby was admitted to the hospital with a 1-week history of rhinitis, cough, fever, and a peeling rash on her hands and feet. Four days after admission she was intubated because of periods of breathing difficulty. The baby was successfully treated with intravenous penicillin and released 14 days later. The baby's father, a 26 year old urban man, had previously had a painless chancre on his penis. The baby's mother became infected during pregnancy and still requires treatment for the condition. Syphilis; Treponema pallidum (spirochete) A 62-year-old woman with a previous history of gastric ulcers presents to her gastrointestinal clinic. Recently she has noticed increasing episodes of heartburn with pressure in the abdomen which radiates to her chest and neck. A biopsy of the stomach shows moderate gastritis. Large numbers of a slightly curved gram- negative rods were also seen on a Gram stain of the biopsy sample; positive for the presence of large amounts of urease Ulcers; Helicobacter pylori A female patient presents to the emergency room with a history of cramping, abdominal pain over the previous 3 days, and vaginal bleeding. She gives no history of urinary tract infection, discharge, chills, fever, or vomiting. The pain has increased over the previous 24 hours, and she is now experiencing a pain in her right side. On examination she has a fever and pelvic pain. An endocervical swab was taken and found obligate intracellular bacteria producing the infection. Chlamydia trachomatis A young woman, who has just returned from a vacation in South America, is admitted to the emergency room with vomiting and severe diarrhea, which has been going on for about 3 hours and is accompanied by muscle cramps and a severe thirst. On examination, the patient is found to have a lowered blood pressure and rapid heart rate; her eyes appear somewhat sunken. She is producing copious amounts of "rice water stools" (odorless and flecked with mucus) which contain gram-negative, curved, motile bacteria with a brisk, darting motility. Vibrio cholera Two days after eating raw eggs, a 30 year old herpetologist starts to exhibit abdominal pain, cramping, diarrhea and nausea. A stool sample reveals fecal leukocytes. Gram negative rods that are motile and produce H2S are cultured. Salmonella enteritidis In the 1990's, the bioweapon plant accidentally released a plume of endospores in a city in Russia. It began as a nonspecific flu-like illness characterized by fever, muscle aches, headache, cough and mild chest discomfort. Then there was a rapid deterioration marked by high fever, difficulty breathing, lack of oxygen and shock. There were 96 victims in all. Livestock in the area died of a disease with similar symptoms. Bacillus anthracis; inhalation anthrax This disease is a rare food-borne illness in the US but is of significant concern to women who are pregnant. The pathogen can survive on cold surfaces and multiply at refrigerator temperatures. The pathogen can infect the developing fetus and has a 25% mortality rate. Listeria monocytogenes January 6, 2000 in Colorado, a full term 3 month old infant was evaluated by her pediatrician for a runny nose and cough of 7 days duration. A test for RSV was negative. Jan 17 Symptoms had progressed to a near continuous paroxysmal cough, breathing difficulty, fever and vomiting after a spasm of coughing. Cyanosis (blue tint = lack of oxygen) of the skin was noted. A chest radiograph revealed marked pneumonia. Jan 22 the infant was placed on mechanical ventilation. The infant suffered multisystem organ failure and hemorrhage of the frontal lobe of the brain. Death Jan 25. Bordetella pertussis