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Three individuals living on the same floor in a university dormitory residence develop symptoms and signs of pneumonia. The diagnosis is confirmed by CXR, and sputum samples are positive for S. pneumoniae. In an outbreak, which of the following conditions most likely predisposed these three individuals to developing pneumococcal pneumonia?
It is possible that such outbreaks can occur in people with no predisposing factors, unlike the vast majority of sporadic cases. However, the only common predisposing factor in a young healthy population such as this would be a previous viral respiratory infection.
A 78-year-old woman with a prior stroke is not feeling well. Her appetite is poor, and today her family noticed that she is confused so they sent her to the emergency room. She reports no cough, fever, or sputum production but her CXR reveals a left lower lobe infiltrate. Blood cultures are drawn, and she is started on antibiotics. The next day the cultures are positive for S. pneumoniae sensitive to penicillin. Which of the following is the most likely complication of pneumococcal pneumonia?
Approximately 2% of cases of pneumococcal pneumonia are complicated by empyema. However, not all pleural effusions in the setting of pneumococcal pneumonia represent pleural infection. Frank pus, a positive Gram stain, or a pH = 7.1 on thoracentesis suggest empyema and the need for aggressive drainage.
A 23-year-old woman presents with cough, malaise, and fever. She reports minimal whitish sputum production and now has chest soreness from coughing so much. She has no other past medical history and no risk factors for HIV. On examination, her temperature is 38.3C, pharynx is normal, and lungs are clear. CXR reveals diffuse bilateral infiltrates. Mycoplasma pneumonia is considered in the possible differential diagnosis of her pneumonia. Which other symptom besides cough is also prominent in patients with mycoplasma pneumonia?
The most common presentation is with cough and headache. Both can be quite severe. Cough becomes more prominent if a lower respiratory tract infection ensues, but sputum production is not usually prominent. Shaking chills and pleuritic chest pain are quite uncommon.
A 24-year-old woman has new symptoms of fever, headache, myalgia, and macular rash. She recently went on a camping trip with friends to the South-Central United States. She endured many “bug bites” during the trip but does not specifically recall any tick bites. The rash consists of macules 3 mm in size on her hands and feet. A clinical diagnosis of RMSF is made and she is started on treatment. Serology is drawn to confirm the diagnosis. Which of the following is the most likely causative organism?
RMSF is the most severe of the rickettsial diseases and has been documented in 48 American states, Canada, and parts of Central and South America. The specific tick that is the vector for this rickettsial disease varies in different geographical locations.
A previously healthy 43-year-old man presents with symptoms of cough, fever, weight loss, and lymphadenopathy for the past 2 months. His physical examination reveals multiple axillary and cervical lymph nodes and oropharyngeal ulcerations. His CXR reveals fibronodular pulmonary infiltrates in the apex, his sputum is negative for TB, and the HIV test is negative. A bronchoalveolar lavage (BAL) confirms the diagnosis.
Disseminated histoplasmosis has many features in common with hematogenously disseminated TB. Common findings include fever, weight loss, cough, lymphadenopathy, anemia, abnormal liver enzymes, and hepatosplenomegaly. The chronic pulmonary disease is characterized by cough, increasing sputum production, and apical infiltrates. Onethird improve or stabilize spontaneously while the remainder progress slowly to develop cavitation of the upper lobes and altered pulmonary function. In histoplasmosis, oropharyngeal ulcerations begin as solitary indurated plaques with no pain present at first, although eventually pain becomes deep-seated. These oropharyngeal manifestations are usually part of disseminated infection.
A 34-year-old man presents with fever, cough, and sputum production. The CXR reveals a thin-walled pulmonary cavity. His tests for TB and HIV are negative. Four weeks ago, he was traveling in southern California, including visiting the San Joaquin valley. While there he did experience a “flu-like” illness, which slowly improved but then his symptoms of cough and sputum started. A BAL confirmed the diagnosis.
In coccidioidomycosis, hemoptysis may call attention to cavitations, or patients may complain of pain at the cavity site. Only half of the patients with a thin-walled pulmonary cavity secondary to coccidioidomycosis will have symptoms, however.
A 42-year-old man presents with symptoms of cough, sputum, fever, and weight loss. His CXR reveals upper lobe pulmonary infiltrates and his Mantoux test (purified protein derivative [PPD]) is positive. He emigrated from Southeast Asia 3 years ago.
The intracutaneous tuberculin test with purified protein derivative (PPD) is read for evidence of delayed hypersensitivity at 48 hours. Although induration >10 mm is felt to be positive, interpretation is really dependent on the population being studied. In an HIV-infected patient, any reaction should be considered significant. When testing household contacts, >5 mm is probably enough to warrant prophylactic treatment.
A 25-year-old woman presents with fever, night sweats, and muscles aches for the past 1 month. She was previously well. On examination, she has axillary and cervical lymph nodes, but no active joints or hepatosplenomegaly. She currently works on a hog farm. Her investigations are negative for EBV, CMV, and HIV. Serologic tests for the infecting agent confirm the diagnosis in her.
In the United States, brucellosis is rare and found most commonly among farmers, meat-processing workers, and veterinarians. Transmission is by contact of Brucella organisms with abraded skin, through the conjunctiva, or by inhalation. Person-to-person transmission is rare or nonexistent. The disease can be acute, localized, or chronic. It requires prolonged antibiotic treatment. A typical treatment course would be doxycycline plus an aminoglycoside for 4 weeks followed by a further 4 weeks of doxycycline and rifampin.
A 42-year-old man presents with sudden-onset fever, chills, headaches, myalgias, and arthralgias. He has no prior medical history, but noticed a new ulcer on his hand 1 week ago. On examination, there is a small “punched out” ulcer, which is erythematous and indurated on his hand, as well as epitrochlear and axillary lymph nodes that are tender. As a hobby, he keeps rabbits in a large pen outside his house and recalls being bitten by one 2 weeks ago. Serologic testing for the organism confirms the diagnosis.
Tularemia can be acquired through direct contact with an infected rabbit, which may occur in preparation or cooking inadequately. The incubation period is 2–5 days, and the syndrome includes fevers, chills, headaches, myalgias, and tender hepatosplenomegaly. In addition, specific syndromes such as ulceroglandular or oculoglandular tularemia can accompany the nonspecific syndrome.
A 28-year-old man presents with a new genital ulcer on his penis that is painless. He is sexually active and noticed the lesion 1 week ago. The ulcer is 1 cm in size, has an eroded base, and an indurated margin. Dark-field examination of the ulcer fluid confirmed the diagnosis.
On dark-field examination, T. pallidum (the spirochete that causes syphilis) is a thin, delicate organism with tapering ends and 6–14 spirals. When dark-field examination is not possible, direct fluorescent antibody tests are used.
A 35-year-old woman develops nausea, vomiting, abdominal pain, and diarrhea 1 day after attending an outdoor picnic. Other people who attended the picnic have similar gastrointestinal symptoms. Most symptomatic individuals recall having egg salad sandwiches.
Salmonellosis is an acute infection resulting from ingestion of food containing bacteria and is characterized by abdominal pain and diarrhea. Salmonella gastroenteritis is not usually treated with antibiotics because the length of the illness is not shortened, but the length of time the organism is carried is increased. Antibiotics are used for more serious systemic Salmonella infections.
A 34-year-old man who works as a carpenter presents with symptoms of jaw discomfort, dysphagia, and pain as well as stiffness in his neck, back, and shoulders. On examination, he is unable to open his jaw, his proximal limb muscles are stiff as is his abdomen and back, but the hands and feet are relatively spared. He occasionally has violent generalized muscles spasms that cause him to stop breathing, but there is no loss of consciousness. A clinical diagnosis is made and he is treated with antibiotics, antitoxin, and diazepam as well as muscle relaxants for the spasms.
Patients with tetanus develop hypertonus, seizures, respiratory distress, and asphyxia unless they are treated with diazepam and muscle relaxants. The treatment of tetanus requires diazepam, muscle relaxants, antitoxin, respiratory care, and managing autonomic dysfunction. Antibiotics are given but are probably of little help.
Infection with this organism during pregnancy can cause congenital hydrocephalus.
Congenital toxoplasmosis is initiated in utero usually as a complication of a primary infection. Infants may be asymptomatic at birth but later can present with a multitude of signs and symptoms, including chorioretinitis, strabismus, epilepsy, and psychomotor retardation. The presence of hydrocephalus is a bad prognostic sign.
For this infectious disease, preventive measures are no longer used since it has been effectively eradicated.
Preventive measures are not used because smallpox is thought to be eradicated worldwide, and vaccination may be associated with serious side effects. As humans are the only reservoir for smallpox, there is no longer any risk of infection from natural sources. However, smallpox could be used in bioterrorism