Chlamydiae, and Mycoplasma


(From Public Health Image Library. Content provider: Center for Disease Control.)


a. Coxiella burnetii


b. Group A streptococci (Streptococcus pyogenes)


c. Rickettsia prowazekii


d. Rickettsia ricketsii


e. Salmonella typhi


325. A 19-year-old college student presents to the university infirmary with what the doctor thought was NGU. The physician had a very hard time isolating a causative organism from the young man. The clinical lab finally got the organism to grow in vitro and they reported that the offending organism produced extremely small colonies and would only grow in the presence of urea. The organism often died rapidly after the initial isolation. The organism causing this student’s NGU was which of the following?


a. Coxiella burnetii


b. Mycoplasma genitalium


c. Mycoplasma hominis


d. Mycoplasma pneumoniae


e. Ureaplasma urealyticum


326. A 15-year-old boy presents to his family doctor and reports that he was not feeling very good. He says that he has been feeling “lousy” for the past 2 weeks with a fever, runny nose, headaches, and no energy. He also has a nonproductive cough. The doctor orders a pulmonary x-ray that demonstrates no consolidation and only patchy opacity in the lower lobes of the lungs. The boy’s serum is positive for cold agglutinins and antibodies against Streptococcus MG. Which of the following bacteria is responsible for his infection?


a. Chlamydia trachomatis


b. Chlamydophila pneumoniae


c. Chlamydophila psittaci


d. Mycoplasma hominis


e. Mycoplasma pneumoniae


327. A 40-year-old man develops a cough that is nonproductive and goes to see his family doctor. He says that he has been feeling “lousy” and has bronchitis, sinusitis, and a sore throat. The doctor orders an x-ray that does not show consolidation, but rather a patchy infiltrate in his upper right lung. The man denies taking any new pets or animals recently into his house. A Gram-stain of the sputum specimen shows a few Gram-negative rods that do not stain very well. Samples sent to the clinical laboratory do not grow on normal laboratory media (eg, blood agar), but do grow in monolayer cells in tissue culture. What bacterium is most likely to be the cause of this man’s infection?


a. Chlamydia trachomatis


b. Chlamydophila psittaci


c. Chlamydophila pneumoniae


d. Mycoplasma pneumoniae


e. Streptococcus pneumoniae


328. A 35-year-old woman living in Minnesota goes to her family physician. She complains that for the past 8 days she has experienced a flu-like illness. The illness consisted of muscle pain, lethargy, headaches, and a high fever (almost 41°C). She states that she had removed several ticks from around her ankles about 14 days ago. The physician gives her a shot of penicillin, but when she returns to see him about a week later, she reports no improvement. The physician then draws her blood and submits it to a clinical laboratory for identification. No bacteria grew out on blood agar, but a Giemsa stain of the blood culture showed coccobacillary organisms inside polymorphonuclear neutrophils. Which of the following bacteria was most likely to be the cause of her illness?


a. Anaplasma phagocytophilum


b. Coxiella burnetii


c. Chlamydophila pneumoniae


d. Chlamydophila psittaci


e. Rickettsia rickettsii


329. A 27-year-old man presents to his family doctor because he has been having a mucopurulent discharge from his penis. He had recently visited a prostitute and he had unprotected sex with her. He was afraid that he had caught the “clap”. He did not have a fever and he said he experienced no pain upon urination. The doctor noted a white urethral discharge from the man’s penis. This discharge was then sent to the clinical laboratory. Because the physician suspected Neisseria gonorrheae infection, the lab stained the specimen and tried to grow it on blood agar. The causative organism did not grow on blood agar, but would only grow in certain cells lines. What was the organism that caused this man’s infection?


a. Chlamydophila pneumoniae


b. Chlamydophila psittaci


c. Chlamydia trachomatis


d. Neisseria gonorrheae


e. Treponema pallidum


330. A physician was asked to come to an Indian reservation in South Dakota because of an outbreak of a serious eye infection. The infection was believed to have spread from person to person by infected towels at the gymnasium. Patients reported conjunctivitis with widespread inflammation. In some cases, the patient’s conjunctiva became so damaged, that the eyelids turned inward, thus scratching the eyeball every time they blinked. In some patients, there was corneal scarring and invasion of blood vessels into the cornea. Fortunately, the physician recognized what the disease was, its cause, and how to treat it. He administered azithromycin in one dose and the infections resolved. What organism was causing the described symptoms?


a. Chlamydia trachomatis


b. Chlamydophila pneumoniae


c. Chlamydophila psittaci


d. Rickettsia prowazekii


e. Rickettsia rickettsii


331. A 45-year-old man reported to the emergency room in respiratory distress. His symptoms included muscle pain, congestion, a dry cough, and difficulty breathing. He also was experiencing fever and chills. A chest x-ray showed consolidation of the left lower lobe, and a patchy infiltrate of his right upper lobe. He was given a shot of penicillin and hospitalized. He did not improve on this antibiotic so he was given doxycycline, which allowed for his improvement. It was decided to give doxycycline after his attending physician learned he was a bird enthusiast and had recently received an African parrot that had arrived sick and had died. What was the name of the organism with which the man was infected?


a. Chlamydophila pneumoniae


b. Chlamydophila psittaci


c. Chlamydia trachomatis


d. Rickettsia prowazekii


e. Rickettsia rickettsii


332. A 50-year-old man presented to his family doctor complaining of flu-like symptoms. The doctor gave him a shot of penicillin and sent him home. The man came back a week later and in fact, felt worse. The man was a rancher and raised a lot of cattle. He told the doctor that he had congenital heart disease and an attack of rheumatic fever when he was young. The man now complained of fever, night sweats, continual coughing, weight loss, and lethargy. The doctor had the man hospitalized because he now suspected subacute bacterial endocarditis (SBE). A culture of his blood did not show any bacterial growth, but a serum analysis for antibodies against a certain bacterium was positive. As a result of finding antibodies to this organism, treatment with doxycycline was begun and the patient improved and was released from the hospital. What was the name of the organism with which the man was infected?


a. Chlamydophila psittaci


b. Chlamydophila pneumoniae


c. Chlamydia trachomatis


d. Coxiella burnetii


e. Viridans streptococci


333. In July of 1987 in Texas, a man went to his family doctor complaining of flu-like symptoms, high fever, lethargy, muscle pain, and a headache. He complained that he just felt “lousy”. When the doctor took the patient’s history, he learned that the man was an avid hiker and camper. In fact, the man just came back from a recent camping trip to South Carolina. The man remembered removing a blood-filled tick from his leg on that trip. He had killed the tick and thought nothing more of it. Now, he felt it might be relevant. The doctor also felt this information was relevant and asked for a Giemsa stain of the man’s blood by the clinical lab. The results came back stating that there were morulae inside the monocytes in the man’s blood. The doctor, based on these results, immediately started the man on doxycycline because he felt the man was infected with which organism?


a. Amblyomma americanum


b. Anaplasma phagocytophilum


c. Ehrlichia canis


d. Ehrlichia ewingii


e. Ehrlichia chaffeensis


334. A United States businessman presented to the emergency room in New York City. He complained of severe headaches, muscle pain, and fever. He had a maculopapular rash on his trunk that was moving to his arms and legs. The emergency room doctors were stumped as to what might be causing this disease state. When they took his history, he told them that he had just come back from a business trip to Japan where he had spent a few days camping in the mountains and had been bitten by some insects. He stated that he never saw the insects, so he did not know what kind they were. He said he knew what fleas and ticks looked like and he was sure that he was not bitten by either of those. In fact, he could show the doctors the eschars of the insect bites. When asked how long ago this was, he replied “about 11 days”. Because of this information gathered by taking the patient’s history, the emergency room doctors felt confident they knew what had caused the patient’s symptoms. They gave the patient doxycycline and told him to see his family doctor for a follow-up after 1 week. When this man went to his family doctor, he was greatly improved. What organism did the New York businessman have that had caused his infection?


a. Dermacentor andersoni


b. Orientia tsutsugamushi


c. Rickettsia prowazekii


d. Rickettsia rickettsii


e. Rickettsia typhi




Answers


296. The answer is c. (Brooks, pp 344-345. Levinson, pp 171-172. Murray, pp 421-426. Ryan, pp 409, 463. Toy, p 116.) Unlike chlamydiae, mycoplasmas can replicate in cell-free media. They lack a rigid cell wall and are bound by a triple-layer unit membrane. For this reason, they are completely resistant to the action of penicillins.


297. The answer is a. (Brooks, pp 353-354. Levinson, pp 182-184. Murray, pp 438-439. Ryan, p 477.) Q fever is an acute, flu-like illness caused by C. burnetii. It is one rickettsial disease not transmitted by the bite of a tick. C. burnetii is found in high concentrations in the urine, feces, and placental tissue/amniotic fluid of cattle, goats, and sheep. Transmission to humans is by aerosol inhalation of those specimens. Rickettsia is present in the United States and South America, but is transmitted by ticks that feed on rodents or dogs. The parasitic Taenia species are transmitted by ingestion of under-cooked meat.


298. The answer is c. (Brooks, pp 350-354. Levinson, pp 182-184. Murray, pp 427-436. Ryan, pp 472-473.) Rickettsiae are obligate intracellular parasites that depend on host cells for their phosphorylated energy compounds. The significant rickettsial diseases in North America include RMSF (R. rick-ettsii), Q fever (C. burnetii), and typhus (R. prowazekii, R. typhi). Laboratory diagnosis of rickettsial disease is based on serologic analysis rather than isolation of the organism.


299. The answer is c. (Brooks, pp 364-365. Levinson, pp 179-181. Murray, pp 441-450. Ryan, p 469.) Ornithosis (psittacosis) is caused by C. psittaci. Humans usually contract the disease from infected birds kept as pets or from infected poultry, including poultry in dressing plants. Although ornithosis may be asymptomatic in humans, severe pneumonia can develop. Fortunately, the disease is cured easily with tetracycline. Bacillus anthracis is a spore-forming, gram-positive bacillus that has a protective capsule made of glutamic acid (amino acid) residues. Humans are infected accidentally by contact with infected animals or their products. Skin lesions, seen most often, are known as woolsorter’s disease. Leptospira organisms are tightly coiled spirochetes. Human contact is often in water, where the organism enters breaks in the skin. They produce hemorrhage and necrosis in the liver and kidneys and often present as aseptic meningitis. Relapsing fever is caused by Borrelia recurrentis and is transmitted by the body louse or Ornithodoros ticks. An unusual feature of this disease is the selection of new antigenic forms of the organism after host antibody formation. Q fever is caused by a rickettsial organism, C. burnetii.


300. The answer is b. (Brooks, pp 350-354. Levinson, pp 182-184. Murray, pp 427-436. Ryan, p 477.) Most rickettsial diseases are transmitted to humans by way of arthropod vectors. The only exception is Q fever, which is caused by C. burnetii.

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Mar 17, 2017 | Posted by in MICROBIOLOGY | Comments Off on Chlamydiae, and Mycoplasma
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