A 53-year-old insulin-dependent diabetic, who underwent a cadaveric renal transplant 1 year prior to admission, presents with fever and cough of 3 weeks duration. He works as a long-haul trucker, carting fruit from McAllen, Texas (on the Texas-Mexico border) to Fresno, California. He does not smoke. His PPD skin test prior to admission was positive. On physical examination, his respiratory rate is 25, his oral temperature is 101°F, his lungs have rhonchi and de creased breath sounds on the left. His CXR is shown in Figure.
What is the best diagnostic approach?
A. PPD skin testing
B. urine histoplasma antigen testing
C. serum cryptococcal antigen testing
D. sputum for silver staining for P. jiroveci
E. fiberoptic bronchoscopy with bronchial alveolar lavage
Correct Answer: E Section: (none)
Explanation:
The clinical picture is most consistent with disease caused by C. immitis. This is due both to the nature of the cavitary lesion on CXR and the endemic area. Figure 1-4 shows a peripheral, thinwalled cavitary lesion on CXR as well as a right lower lobe infiltrate. As a renal transplant recipient 1 year out, this patient is likely to have infections with tuberculosis and disseminated fungal infections. It is interesting that the route that he travels is through the lower Sonoran life zone where coccidiomycosis is endemic. CMV produces a diffuse interstitial infiltrate pattern on CXR, as does Pneumocystis and H. capsulatum. Fiberoptic bronchoscopy with bronchial alveolar lavage should be performed in any patient with this clinical presentation who is immunocompromised because of the lack of ability to produce a good sputum specimen. We know that the patient is PPD positive, so skin testing is not useful. The patient is not mentioned to be in the endemic area for histoplasmosis. Serum cryptococcal antigen testing is a remote possibility. While Cryptococcus can produce a pulmonary disease with cavitary lesions, in immunocompromised hosts such as this, the patient more likely would present with meningitis.
Question 742:
A 53-year-old insulin-dependent diabetic, who underwent a cadaveric renal transplant 1 year prior to admission, presents with fever and cough of 3 weeks duration. He works as a long-haul trucker, carting fruit from McAllen, Texas (on the Texas-Mexico border) to Fresno, California. He does not smoke. His PPD skin test prior to admission was positive. On physical examination, his respiratory rate is 25, his oral temperature is 101°F, his lungs have rhonchi and de creased breath sounds on the left. His CXR is shown in Figure.
What organism besides Mycobacterium tuberculosis leads your differential as a cause of pneumonia in this case?
A. Haemophilus influenzae
B. CMV
C. P. jiroveci
D. C. immitis
E. Histoplasma capsulatum
Correct Answer: D Section: (none)
Explanation:
The clinical picture is most consistent with disease caused by C. immitis. This is due both to the nature of the cavitary lesion on CXR and the endemic area. Figure 1-4 shows a peripheral, thinwalled cavitary lesion on CXR as well as a right lower lobe infiltrate. As a renal transplant recipient 1 year out, this patient is likely to have infections with tuberculosis and disseminated fungal infections. It is interesting that the route that he travels is through the lower Sonoran life zone where coccidiomycosis is endemic. CMV produces a diffuse interstitial infiltrate pattern on CXR, as does Pneumocystis and H. capsulatum. Fiberoptic bronchoscopy with bronchial alveolar lavage should be performed in any patient with this clinical presentation who is immunocompromised because of the lack of ability to produce a good sputum specimen. We know that the patient is PPD positive, so skin testing is not useful. The patient is not mentioned to be in the endemic area for histoplasmosis. Serum cryptococcal antigen testing is a remote possibility. While Cryptococcus can produce a pulmonary disease with cavitary lesions, in immunocompromised hosts such as this, the patient more likely would present with meningitis.
Question 743:
A 34-year-old amateur spelunker develops cough, dyspnea, and fever 2 weeks after a caving expedition to caves in Kentucky. On physical examination, the patient's temperature is 102°F and respiratory rate is 24. On pulmonary examination, there are diffuse crackles bilaterally. A CXR is shown in Figure .
Which of these is the most appropriate statement about infection control of this patient if the patient is hospitalized?
A. The patient is not likely to need respiratory isolation.
B. The patient should be placed in respiratory isolation if histoplasmosis is suspected.
C. The patient should be placed in respiratory isolation if P. jiroveci is suspected.
D. The patient should be placed in respiratory isolation if pulmonary aspergillosis is suspected.
E. The patient should be placed in respiratory isolation if cryptococcal pneumonia is suspected.
Correct Answer: A Section: (none)
Explanation:
The patient has diffuse interstitial infiltrates on CXR that correspond in time and presentation to acute inhalation histoplasmosis. This would be seen in a patient, such as an amateur spelunker, who has been in a cave with bats. It is the act of crawling through the cave that disturbs the spores of histoplasmosis that grow in the bat guano. The incubation period for influenza is 12 days. It is passed primarily by secretions from the nose spread by hands. The other members of the expedition were not sick, as they might be with influenza. Disseminated aspergillosis occurs in immunocompromised patients who have defects in both cell-mediated and humoral immunity. This patient does not have this. While the CXR could mimic military tuberculosis, the association with caving 14 days before would make tuberculosis less likely and histoplasmosis more likely. There is no history that the patient is immunocompromised with HIV and would be at risk for P. jiroveci pneumonia. Fungal serologies would establish the diagnosis, but acute and convalescent serologies would take 3 weeks for results. These are only useful in outbreak investigations. The other choices do not fit due to the reasons above. Treatment of acute respiratory histoplasmosis is based on severe hypoxia and would require arterial blood gases to establish the need for therapy. None of the fungal infections mentioned are transmissible person to person, therefore respiratory isolation would not be necessary. Histoplasmosis is a dimorphic fungus that grows as a yeast at body temperature and a mold at room temperature. The mold produces the spores that are infectious. A similar situation occurs for Cryptococcus neoformans. C. immitis and aspergillosis are not transmitted from person to person.
Question 744:
A 34-year-old amateur spelunker develops cough, dyspnea, and fever 2 weeks after a caving expedition to caves in Kentucky. On physical examination, the patient's temperature is 102°F and respiratory rate is 24. On pulmonary examination, there are diffuse crackles bilaterally. A CXR is shown in Figure .
What diagnostic test would be most appropriate?
A. serum cryptococcal antigen
B. fungal serologies
C. a PPD skin test
D. an HIV enzyme-linked immunosorbent assay (ELISA) test
E. arterial blood gas determination
Correct Answer: E Section: (none)
Explanation:
The patient has diffuse interstitial infiltrates on CXR that correspond in time and presentation to acute inhalation histoplasmosis. This would be seen in a patient, such as an amateur spelunker, who has been in a cave with bats. It is the act of crawling through the cave that disturbs the spores of histoplasmosis that grow in the bat guano. The incubation period for influenza is 12 days. It is passed primarily by secretions from the nose spread by hands. The other members of the expedition were not sick, as they might be with influenza. Disseminated aspergillosis occurs in immunocompromised patients who have defects in both cell-mediated and humoral immunity. This patient does not have this. While the CXR could mimic military tuberculosis, the association with caving 14 days before would make tuberculosis less likely and histoplasmosis more likely. There is no history that the patient is immunocompromised with HIV and would be at risk for P. jiroveci pneumonia. Fungal serologies would establish the diagnosis, but acute and convalescent serologies would take 3 weeks for results. These are only useful in outbreak investigations. The other choices do not fit due to the reasons above. Treatment of acute respiratory histoplasmosis is based on severe hypoxia and would require arterial blood gases to establish the need for therapy. None of the fungal infections mentioned are transmissible person to person, therefore respiratory isolation would not be necessary. Histoplasmosis is a dimorphic fungus that grows as a yeast at body temperature and a mold at room temperature. The mold produces the spores that are infectious. A similar situation occurs for Cryptococcus neoformans. C. immitis and aspergillosis are not transmitted from person to person.
Question 745:
A 34-year-old amateur spelunker develops cough, dyspnea, and fever 2 weeks after a caving expedition to caves in Kentucky. On physical examination, the patient's temperature is 102°F and respiratory rate is 24. On pulmonary examination, there are diffuse crackles bilaterally. A CXR is shown in Figure
.
Which of the following is the most likely cause of disease in this patient?
A. The patient likely developed influenza from close contact with the other members of the caving expedition.
B. The patient likely has disseminated aspergillosis.
C. The patient likely has miliary tuberculosis.
D. The patient likely has acute pulmonary histoplasmosis.
E. The patient likely has Pneumocystis jiroveci pneumonia.
Correct Answer: D Section: (none)
Explanation:
The patient has diffuse interstitial infiltrates on CXR that correspond in time and presentation to acute inhalation histoplasmosis. This would be seen in a patient, such as an amateur spelunker, who has been in a cave with bats. It is the act of crawling through the cave that disturbs the spores of histoplasmosis that grow in the bat guano. The incubation period for influenza is 12 days. It is passed primarily by secretions from the nose spread by hands. The other members of the expedition were not sick, as they might be with influenza. Disseminated aspergillosis occurs in immunocompromised patients who have defects in both cell-mediated and humoral immunity. This patient does not have this. While the CXR could mimic military tuberculosis, the association with caving 14 days before would make tuberculosis less likely and histoplasmosis more likely. There is no history that the patient is immunocompromised with HIV and would be at risk for P. jiroveci pneumonia. Fungal serologies would establish the diagnosis, but acute and convalescent serologies would take 3 weeks for results. These are only useful in outbreak investigations. The other choices do not fit due to the reasons above. Treatment of acute respiratory histoplasmosis is based on severe hypoxia and would require arterial blood gases to establish the need for therapy. None of the fungal infections mentioned are transmissible person to person, therefore respiratory isolation would not be necessary. Histoplasmosis is a dimorphic fungus that grows as a yeast at body temperature and a mold at room temperature. The mold produces the spores that are infectious. A similar situation occurs for Cryptococcus neoformans. C. immitis and aspergillosis are not transmitted from person to person.
Question 746:
A 26-year-old HIV-positive man is admitted to the hospital for treatment of a varicella-zoster infection. On the fourth day of treatment, he develops an acute renal insufficiency. What is the most likely treatment-related mechanism accounting for the patient's acute renal insufficiency?
A. the formation of toxic metabolites
B. decreased glomerular filtration rate
C. the precipitation of acyclovir in renal tubules
D. direct tubular cytotoxic injury
E. hypersensitivity interstitial nephritis
Correct Answer: C Section: (none)
Explanation:
HIV-positive patients who develop a varicella-zoster infection require aggressive antibiotic therapy. Intravenous acyclovir should be adminstered for a period of 7 days, and oral maintenance therapy should be started for secondary prophylaxis. While acyclovir is usually well tolerated, it can be nephrotoxic when given intravenously. It may crystallize within renal tubules and cause subsequent acute tubular necrosis. Acyclovir is more likely to cause nephrotoxic effects if there is associated dehydration or a preexisting renal insufficiency. Individuals who have a preexisting renal insufficiency should have the dose and frequency of acyclovir administration adjusted according to their baseline creatinine clearance.
Question 747:
A22-year-old male presents to an acute care clinic in order to have two genital lesions evaluated. He first noticed the lesions about 2 weeks ago, but delayed seeking medical care because he believed they were harmless due to the lack of any discomfort. He states that he does engage in unprotected sexual intercourse, with the most recent time being 1 month ago. On examination, the glans penis features two distinct nontender papules with elevated edges surrounding ulcerated craters. They each measure 1 cm in diameter. There is also nontender bilateral inguinal lymphadenopathy. Six hours after treating this patient, he calls your office with complaints of new-onset headache, myalgia, and malaise. He also states that he felt feverish immediately prior to calling and measured his temperature, which was 99.8°F. Which of th e following is most appropriate at this time?
A. Advise transport to the nearest ED for immediate evaluation.
B. Advise use of acetaminophen and provide reassurance.
C. Advise immediate use of Benadryl and then have the patient go to the nearest ED.
D. Start treatment with levaquin.
E. Start treatment with oral corticosteroids.
Correct Answer: B Section: (none)
Explanation:
This patient's presentation is consistent with primary syphilis. Primary syphilis manifests itself usually in the form of solitary or multiple raised, firm papules which eventually erode to form ulcerative craters with raised, indurated margins surrounding the centralized ulcer. These lesions, called chancres, most commonly involve the glans penis in males and the vulva or cervix in females, although they may appear rarely in other areas. Syphilis is caused by the spirochete, T. pallidum, which can be visualized by darkfield microscopy, by silver stain, or by fluorescent antibody microscopy. There is an incubation period of approximately 3 weeks separating the time of initial exposure to T. pallidum and the time of chancre formation. Syphilis is characterized by the presence of latent stages in which there are no signs of clinical disease present. Penicillin is the drug of choice for the treatment of syphilis. In addition to treating patients with diagnosed syphilis, it is recommended that treatment also be administered to all sexual contacts of the past 90 days. It has been demonstrated that up to 30% of asymptomatic sexual contacts of patients with infectious lesions within the past 30 days go on to develop syphilis if left untreated. If left untreated, patients may ultimately develop tertiary syphilis characterized by significant destructive neurologic and cardiovascular symptoms. The mortality rate for untreated tertiary syphilis is approximately 20%.
Cephalosporins and penicillin antibiotics act by interfering with the late stages of bacterial cell wall synthesis, although the precise biochemical reactions are not entirely understood. Peptidoglycan provides mechanical stability to the cell wall because of its high degree of cross-linking with alternating amino pyranoside sugar residues (N-acetylglucosamine and N-acetylmuramic acid). The completion of the crosslinking occurs by the action of the enzyme transpeptidase. This transpeptidase reaction, in which the terminal glycine residue of the pentaglycine bridge is joined to the fourth residue of the pentapeptide (Dalanine) thereby releasing the fifth residue (D-alanine), is inhibited by beta-lactams.
Question 748:
A22-year-old male presents to an acute care clinic in order to have two genital lesions evaluated. He first noticed the lesions about 2 weeks ago, but delayed seeking medical care because he believed they were harmless due to the lack of any discomfort. He states that he does engage in unprotected sexual intercourse, with the most recent time being 1 month ago. On examination, the glans penis features two distinct nontender papules with elevated edges surrounding ulcerated craters. They each measure 1 cm in diameter. There is also nontender bilateral inguinal lymphadenopathy.
The drug of choice for treating this patient works by which of the following mechanisms?
A. interfering with protein synthesis at the ribosome
B. attaching to sterols in cell membranes
C. inhibiting bacterial cell wall synthesis
D. inhibiting the transport of amino acids into bacteria
E. inhibiting dihydrofolate reductase
Correct Answer: C Section: (none)
Explanation:
This patient's presentation is consistent with primary syphilis. Primary syphilis manifests itself usually in the form of solitary or multiple raised, firm papules which eventually erode to form ulcerative craters with raised, indurated margins surrounding the centralized ulcer. These lesions, called chancres, most commonly involve the glans penis in males and the vulva or cervix in females, although they may appear rarely in other areas. Syphilis is caused by the spirochete, T. pallidum, which can be visualized by darkfield microscopy, by silver stain, or by fluorescent antibody microscopy. There is an incubation period of approximately 3 weeks separating the time of initial exposure to T. pallidum and the time of chancre formation. Syphilis is characterized by the presence of latent stages in which there are no signs of clinical disease present. Penicillin is the drug of choice for the treatment of syphilis. In addition to treating patients with diagnosed syphilis, it is recommended that treatment also be administered to all sexual contacts of the past 90 days. It has been demonstrated that up to 30% of asymptomatic sexual contacts of patients with infectious lesions within the past 30 days go on to develop syphilis if left untreated. If left untreated, patients may ultimately develop tertiary syphilis characterized by significant destructive neurologic and cardiovascular symptoms. The mortality rate for untreated tertiary syphilis is approximately 20%.
Cephalosporins and penicillin antibiotics act by interfering with the late stages of bacterial cell wall synthesis, although the precise biochemical reactions are not entirely understood. Peptidoglycan provides mechanical stability to the cell wall because of its high degree of cross-linking with alternating amino pyranoside sugar residues (N-acetylglucosamine and N-acetylmuramic acid). The completion of the cross-linking occurs by the action of the enzyme transpeptidase. This transpeptidase reaction, in which the terminal glycine residue of the pentaglycine bridge is joined to the fourth residue of the pentapeptide (Dalanine) thereby releasing the fifth residue (D-alanine), is inhibited by beta-lactams.
Question 749:
A22-year-old male presents to an acute care clinic in order to have two genital lesions evaluated. He first noticed the lesions about 2 weeks ago, but delayed seeking medical care because he believed they were harmless due to the lack of any discomfort. He states that he does engage in unprotected sexual intercourse, with the most recent time being 1 month ago. On examination, the glans penis features two distinct nontender papules with elevated edges surrounding ulcerated craters. They each measure 1 cm in diameter. There is also nontender bilateral inguinal lymphadenopathy.
Which of the following is true about this patient's condition?
A. The causative agent is a virus.
B. Light microscopy of fluid from the lesions will reveal gram-negative rods in chains.
C. The presence of multiple distinct lesions is uncommon.
D. There is a latent phase in which patients are asymptomatic.
E. Although associated with persistent symptoms if left untreated, it does not carry a significant risk for mortality.
Correct Answer: D Section: (none)
Explanation:
This patient's presentation is consistent with primary syphilis. Primary syphilis manifests itself usually in the form of solitary or multiple raised, firm papules which eventually erode to form ulcerative craters with raised, indurated margins surrounding the centralized ulcer. These lesions, called chancres, most commonly involve the glans penis in males and the vulva or cervix in females, although they may appear rarely in other areas. Syphilis is caused by the spirochete, T. pallidum, which can be visualized by darkfield microscopy, by silver stain, or by fluorescent antibody microscopy. There is an incubation period of approximately 3 weeks separating the time of initial exposure to T. pallidum and the time of chancre formation. Syphilis is characterized by the presence of latent stages in which there are no signs of clinical disease present. Penicillin is the drug of choice for the treatment of syphilis. In addition to treating patients with diagnosed syphilis, it is recommended that treatment also be administered to all sexual contacts of the past 90 days. It has been demonstrated that up to 30% of asymptomatic sexual contacts of patients with infectious lesions within the past 30 days go on to develop syphilis if left untreated. If left untreated, patients may ultimately develop tertiary syphilis characterized by significant destructive neurologic and cardiovascular symptoms. The mortality rate for untreated tertiary syphilis is approximately 20%.
Cephalosporins and penicillin antibiotics act by interfering with the late stages of bacterial cell wall synthesis, although the precise biochemical reactions are not entirely understood. Peptidoglycan provides mechanical stability to the cell wall because of its high degree of cross-linking with alternating amino pyranoside sugar residues (N-acetylglucosamine and N-acetylmuramic acid). The completion of the cross-linking occurs by the action of the enzyme transpeptidase. This transpeptidase reaction, in which the terminal glycine residue of the pentaglycine bridge is joined to the fourth residue of the pentapeptide (Dalanine) thereby releasing the fifth residue (D-alanine), is inhibited by beta-lactams.
Question 750:
A 24-year-old male presents with sore throat, subjective fever, abdominal pain, and bad breath. He says that a neighbor's child is currently being treated for strep throat. On examination, his temperature is 101.1° F and his other vital signs are normal. He appears well. His throat is erythematous and his tonsils are enlarged, but there are no pharyngeal or tonsillar exudates. He has no cervical adenopathy. He has an occasional cough but his lungs are clear. His abdominal examination is normal. The presence of which of the following findings is a clinical predictor for the diagnosis of streptococcal pharyngitis?
Which of the following is the recommended first-line agent for the treatment of group A streptococcal pharyngitis?
A. levofloxacin
B. amoxicillin
C. penicillin
D. amoxicillin-clavulinic acid
E. clindamycin
Correct Answer: C Section: (none)
Explanation:
Pharyngitis is a commonly encountered problem in primary care. Patients with upper respiratory symptoms are often convinced that they need antibiotics. Often the etiology is viral, but ruling out bacterial etiology is crucial as the secondary complications can be severe. In terms of group Astrep pharyngitis, it is often difficult to make a clinical diagnosis based on one or two factors. Many studies have been performed to guide the clinician in making an empiric diagnosis of group A strep pharyngitis. Fever, tonsillar exudates, tender anterior cervical lymphadenopathy, absence of cough and tonsillar hypertrophy are all positive predictors. A patient who has at least two of these criteria should have a rapid strep test or culture--with treatment initiated if the test is positive. When a patient meets three or more criteria and is ill appearing, empiric treatment may be justified. If the patient has a negative rapid strep test and the clinician is suspicious, empiric treatment may be started and throat culture should be obtained. Apatient with a positive culture or rapid strep test should be treated, but a test of cure does not need to be performed. The throat culture has a sensitivity of 97% and specificity of 99%, while the rapid strep test has a sensitivity of 8097% and a specificity of >95%.
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