WBR0046: Difference between revisions

Jump to navigation Jump to search
← Older editNewer edit →
VisualWikitext
No edit summary
YazanDaaboul (talk | contribs)
Bots, Bureaucrats, bureaucrats, editnews, exportpages, interwiki, nocaptcha, nukepages, oversight, smwadministrator, Administrators, Widget editors
9,960 edits
No edit summary
Line 1: Line 1:
{{WBRQuestion
{{WBRQuestion
|QuestionAuthor=William J Gibson (Reviewed by {{Rim}})
|QuestionAuthor=William J Gibson (Reviewed by {{Rim}} and Yazan Daaboul)
|ExamType=USMLE Step 1
|ExamType=USMLE Step 1
|MainCategory=Microbiology, Pharmacology
|MainCategory=Microbiology, Pharmacology
Line 8: Line 8:
|MainCategory=Microbiology, Pharmacology
|MainCategory=Microbiology, Pharmacology
|SubCategory=Pulmonology, General Principles
|SubCategory=Pulmonology, General Principles
|MainCategory=Microbiology, Pharmacology
|MainCategory=Microbiology, Pharmacology
|MainCategory=Microbiology, Pharmacology
|MainCategory=Microbiology, Pharmacology
|MainCategory=Microbiology, Pharmacology
Line 20: Line 21:
|MainCategory=Microbiology, Pharmacology
|MainCategory=Microbiology, Pharmacology
|SubCategory=Pulmonology, General Principles
|SubCategory=Pulmonology, General Principles
|Prompt=A 20-year-old woman presents to her primary care physician complaining of dyspnea and malaise.  Over the past week she has experienced increasing dyspnea, bronchitis and fatigue which limits her otherwise vigorous exercise but does not interfere with daily activities. She denies abnormal sputum production and any significant past medical history. On physical examination, she has a pulse of 72 beats/min, temperature of 101 F (38.3 C), respiratory rate of 22/min and oxygen saturation of 94% on room air.  Cardiac examination is normal but respiratory exam reveals diffuse crackles. Which of the following is the most appropriate treatment?
|Prompt=A 27-year-old shipyard worker presents to his primary care physician complaining of dyspnea and fatigue of one week duration.  Over the past week,  he has been experiencing gradually worsening new-onset fatigue and dyspnea. Despite his symptoms, the patient confirms that his condition is "not so bad". His past medical history is not significant. He denies any allergies or use of medications. His blood pressure is 112/82 mmHg, heart rate is 72/min, temperature is 101 F (38.3 C), respiratory rate is 24/min, and oxygen saturation is 92% on room air.  Physical examination is remarkable for the presence of diffuse crackles over both lung fields. Chest xray is ordered; it shows diffuse interstitial infiltrates over both lung fields with no focal consolidation. Which of the following is the most appropriate treatment for this patient's condition?
|Explanation=The patient is suffering from a case of [[atypical pneumonia]], a respiratory infection which often causes systemic symptoms such as [[fever]], [[headache]] and [[myalgia]].  Atypical pneumonia differs from typical pneumonia in that [[atypical pneumonias]] often do not respond to common [[antibiotics]] (eg [[sulfonamides]], or [[beta-lactams]]), do not show signs of consolidation, nor give rise to [[leukocytosis]].  On chest X-ray, patients often show a diffuse interstitial infiltrate which conveys the appearance of a more severe infection than the patient’s symptoms suggest.  Because patients often have mild symptoms, [[atypical pneumonia]] is alternatively referred to as “walking pneumonia.”  While walking pneumonia due to [[mycoplasma]] infection is a distinct entity, the more general distinction between typical and [[atypical pneumonias]] is largely historical and has more recently been de-emphasized.
|Explanation=The patient is suffering from a case of [[atypical pneumonia]], a respiratory infection which often causes systemic symptoms such as [[fever]], [[headache]] and [[myalgia]].  Atypical pneumonia differs from typical pneumonia in that [[atypical pneumonias]] often does not respond to common [[antibiotics]] (eg [[sulfonamides]], or [[beta-lactams]]), does not show signs of consolidation, nor does it give rise to [[leukocytosis]].  On chest xray, patients often show diffuse interstitial infiltrates which conveys the appearance of a more severe infection than the patient’s symptoms suggest.  Because patients often have mild symptoms, [[atypical pneumonia]] is alternatively referred to as “walking pneumonia".  
 
Atypical pneumonia is most often caused by [[Mycoplasma pneumoniae]] which usually infects older children and young adults (patients <30 years old).  Mycoplasma pneumoniae is a mere 0.3 um in size and is the only bacteria which does not possess a cell wall.  Mycoplasma pneumoniae can be cultured on Eaton's agar.  [[Mycoplasma pneumoniae]] can be treated with [[macrolides]] (eg [[erythromycin]]) or [[tetracyclines]].


Atypical pneumonia is most often caused by [[''Mycoplasma pneumoniae'']], which usually infects older children and young adults less than 30 years of age. [[''Mycoplasma pneumoniae'']] can be treated with [[macrolides]] (eg [[azithromycin]]) or [[tetracyclines]].
[[File:Cell antibiotics.jpg|600px]]
[[File:Cell antibiotics.jpg|600px]]


Note: This question is linked to WBR0044, WBR0045
Note: This question is linked to WBR0044, WBR0045
|AnswerA=Chloramphenicol
|AnswerA=Chloramphenicol
|AnswerAExp=[[Chloramphenicol]] is not the drug of choice for [[Mycoplasma pneumoniae]] infection. Chloramphenicol is known for causing [[gray baby syndrome]].
|AnswerAExp=[[Chloramphenicol]] is not the drug of choice for [[''Mycoplasma pneumoniae'']] infection. Chloramphenicol is known for causing [[gray baby syndrome]].
|AnswerB=Trimethoprim-Sulfamethoxazole
|AnswerB=Trimethoprim-Sulfamethoxazole
|AnswerBExp=[[Trimethoprim-Sulfamethoxazole]] (TMP-SMX) is not the drug of choice for Mycoplasma infection.  TMP-SMX is often used for simple [[UTI]]s/[[cystitis]].
|AnswerBExp=[[Trimethoprim-Sulfamethoxazole]] (TMP-SMX) is not the drug of choice for ''Mycoplasma'' infection.  TMP-SMX is often used for simple [[UTI]], [[cystitis]], [[''Pseudomas'']] infection, and [[''Pneumocystis'']] infection in HIV-positive patients. TMP-SMX may also be used as prophylaxis for[[''Pneumocystis'']] and [[toxoplasma]] in HIV-positive patients.
|AnswerC=Erythromycin
|AnswerC=Azithromycin
|AnswerCExp=[[Erythromycin]] is a macrolide antibiotic that blocks the 50s ribosomal subunit and can be used to treat [[Mycoplasma pneumoniae]] infection.
|AnswerCExp=[[Azithromycin]] is a macrolide antibiotic that blocks the 50s ribosomal subunit and can be used to treat [[''Mycoplasma pneumoniae'']] infection.
|AnswerD=Penicillin
|AnswerD=Penicillin
|AnswerDExp=[[Penicillin]] is ineffective against Mycoplasma infections because mycoplasma lacks a peptidoglycan cell wall.
|AnswerDExp=[[Penicillin]] is ineffective against ''Mycoplasma'' infections because mycoplasma lacks a peptidoglycan cell wall.
|AnswerE=Aztreonam
|AnswerE=Aztreonam
|AnswerEExp=[[Aztreonam]], a beta-lactam antibiotic resistant to [[beta-lactamase]]s, is ineffective against Mycoplasma infections because mycoplasma lacks a peptidoglycan cell wall.
|AnswerEExp=[[Aztreonam]], a beta-lactam antibiotic resistant to [[beta-lactamase]]s, is ineffective against Mycoplasma infections because mycoplasma lacks a peptidoglycan cell wall.
|EducationalObjectives=[[Mycoplasma pneumoniae]] can be treated with [[macrolides]] (eg [[erythromycin]]) or [[tetracyclines]].
|EducationalObjectives=[[Mycoplasma pneumoniae]] can be treated with [[macrolides]] (eg [[azithromycin]]) or [[tetracyclines]].
|References=First Aid 2014 page 145
|References=First Aid 2014 page 145
|RightAnswer=C
|RightAnswer=C

Revision as of 15:10, 1 August 2014
Author [[PageAuthor::William J Gibson (Reviewed by Rim Halaby, M.D. [1] and Yazan Daaboul)]]
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Microbiology, MainCategory::Pharmacology
Sub Category SubCategory::Pulmonology, SubCategory::General Principles
Prompt [[Prompt::A 27-year-old shipyard worker presents to his primary care physician complaining of dyspnea and fatigue of one week duration. Over the past week, he has been experiencing gradually worsening new-onset fatigue and dyspnea. Despite his symptoms, the patient confirms that his condition is "not so bad". His past medical history is not significant. He denies any allergies or use of medications. His blood pressure is 112/82 mmHg, heart rate is 72/min, temperature is 101 F (38.3 C), respiratory rate is 24/min, and oxygen saturation is 92% on room air. Physical examination is remarkable for the presence of diffuse crackles over both lung fields. Chest xray is ordered; it shows diffuse interstitial infiltrates over both lung fields with no focal consolidation. Which of the following is the most appropriate treatment for this patient's condition?]]
Answer A AnswerA::Chloramphenicol
Answer A Explanation [[AnswerAExp::Chloramphenicol is not the drug of choice for ''Mycoplasma pneumoniae'' infection. Chloramphenicol is known for causing gray baby syndrome.]]
Answer B AnswerB::Trimethoprim-Sulfamethoxazole
Answer B Explanation [[AnswerBExp::Trimethoprim-Sulfamethoxazole (TMP-SMX) is not the drug of choice for Mycoplasma infection. TMP-SMX is often used for simple UTI, cystitis, ''Pseudomas'' infection, and ''Pneumocystis'' infection in HIV-positive patients. TMP-SMX may also be used as prophylaxis for''Pneumocystis'' and toxoplasma in HIV-positive patients.]]
Answer C AnswerC::Azithromycin
Answer C Explanation [[AnswerCExp::Azithromycin is a macrolide antibiotic that blocks the 50s ribosomal subunit and can be used to treat ''Mycoplasma pneumoniae'' infection.]]
Answer D AnswerD::Penicillin
Answer D Explanation [[AnswerDExp::Penicillin is ineffective against Mycoplasma infections because mycoplasma lacks a peptidoglycan cell wall.]]
Answer E AnswerE::Aztreonam
Answer E Explanation [[AnswerEExp::Aztreonam, a beta-lactam antibiotic resistant to beta-lactamases, is ineffective against Mycoplasma infections because mycoplasma lacks a peptidoglycan cell wall.]]
Right Answer RightAnswer::C
Explanation [[Explanation::The patient is suffering from a case of atypical pneumonia, a respiratory infection which often causes systemic symptoms such as fever, headache and myalgia. Atypical pneumonia differs from typical pneumonia in that atypical pneumonias often does not respond to common antibiotics (eg sulfonamides, or beta-lactams), does not show signs of consolidation, nor does it give rise to leukocytosis. On chest xray, patients often show diffuse interstitial infiltrates which conveys the appearance of a more severe infection than the patient’s symptoms suggest. Because patients often have mild symptoms, atypical pneumonia is alternatively referred to as “walking pneumonia".

Atypical pneumonia is most often caused by ''Mycoplasma pneumoniae'', which usually infects older children and young adults less than 30 years of age. ''Mycoplasma pneumoniae'' can be treated with macrolides (eg azithromycin) or tetracyclines.

Note: This question is linked to WBR0044, WBR0045
Educational Objective: Mycoplasma pneumoniae can be treated with macrolides (eg azithromycin) or tetracyclines.
References: First Aid 2014 page 145]]

Approved Approved::Yes
Keyword WBRKeyword::Microbiology, WBRKeyword::Mycoplasma, WBRKeyword::Bacteria, WBRKeyword::Pneumonia, WBRKeyword::Infection, WBRKeyword::Antibiotics, WBRKeyword::Drug, WBRKeyword::Drugs, WBRKeyword::Pharmacology
Linked Question Linked::
Order in Linked Questions LinkedOrder::
Retrieved from "https://www.wikidoc.org/index.php?title=WBR0046&oldid=1005848"