Atypical

Atypical US Medical PG Question 1: An 18-year-old male in his first year of college presents to the emergency room with a fever and a severe headache. He reports having unprotected sex with several partners over the past few weeks. Upon examination, the male demonstrates nuchal rigidity and photophobia. His past medical history is notable for a lack of vaccinations beginning from infancy due to his parents' belief that vaccinations may cause autism. The bacteria causing these symptoms would most likely demonstrate which of the following?

• A. Negative catalase test
• B. Gram-negative bacteria (Correct Answer)
• C. Urease positive
• D. Positive quellung reaction
• E. Lactose fermentation

Atypical Explanation: ***Gram-negative bacteria*** - The clinical picture of fever, severe headache, **nuchal rigidity**, and photophobia in an unvaccinated 18-year-old college student strongly suggests **bacterial meningitis** caused by *Neisseria meningitidis*. - *Neisseria meningitidis* is a **Gram-negative diplococcus**, which is the most definitive laboratory characteristic for identifying this organism. - College dormitory settings and unvaccinated status are major risk factors for **meningococcal meningitis**, and Gram stain is typically the first diagnostic step showing Gram-negative diplococci in CSF. *Positive quellung reaction* - The Quellung reaction (capsular swelling) is classically associated with **Streptococcus pneumoniae**, not *Neisseria meningitidis*. - While *N. meningitidis* does have a polysaccharide capsule, the Quellung test is not the standard identification method for this organism. - *S. pneumoniae* would be more common in older adults or those with specific risk factors like asplenia. *Negative catalase test* - *Neisseria meningitidis* is **catalase-positive**, so a negative catalase test would rule out this organism. - Catalase-negative organisms include Streptococcus and Enterococcus species, which have different clinical presentations. *Lactose fermentation* - *Neisseria meningitidis* is a **non-lactose fermenter** and does not utilize lactose fermentation for energy. - Lactose fermentation is characteristic of enteric Gram-negative bacteria like *E. coli* and *Klebsiella*, not Neisseria species. - *N. meningitidis* ferments **maltose and glucose**, which distinguishes it from *N. gonorrhoeae* (glucose only). *Urease positive* - *Neisseria meningitidis* is **urease-negative**, so urease positivity would rule out this organism. - Urease-positive bacteria include *Helicobacter pylori*, *Proteus* species, and *Klebsiella*, none of which typically cause meningitis in this clinical setting.

Atypical US Medical PG Question 2: An investigator is studying the growth of an organism in different media. The organism is inoculated on a petri dish that contains heated sheep blood, vancomycin, nystatin, trimethoprim, and colistin. The resulting growth medium is incubated at 37°C. Numerous small, white colonies are seen after incubation for 48 hours. This organism is most likely to cause which of the following conditions?

• A. Pontiac fever
• B. Pseudomembranous colitis
• C. Hemolytic uremic syndrome
• D. Oral thrush
• E. Gonorrhea (Correct Answer)

Atypical Explanation: ***Gonorrhea*** - The growth medium described is **Thayer-Martin agar**, a selective medium containing **heated sheep blood** (supplies NAD+), **vancomycin** (inhibits Gram-positives), **colistin** (inhibits Gram-negatives), **nystatin** (inhibits fungi), and **trimethoprim** (inhibits Proteus). This medium is specifically designed for the isolation of *Neisseria gonorrhoeae* from polymicrobial samples. - *Neisseria gonorrhoeae* typically grows as **small, translucent-to-white colonies** on selective media like Thayer-Martin agar, and incubation at 37°C in CO2 (not explicitly mentioned but often required) for 24-48 hours yields visible growth, causing **gonorrhea**. *Pontiac fever* - Pontiac fever is a mild, self-limiting form of **legionellosis**, caused by *Legionella pneumophila*. - *Legionella* requires a specialized medium such as **buffered charcoal yeast extract (BCYE) agar** for growth, not Thayer-Martin agar. *Pseudomembranous colitis* - This condition is caused by **toxin-producing *Clostridioides difficile***, often after antibiotic use. - *C. difficile* is an obligate anaerobe and requires **anaerobic conditions** and specific selective media (e.g., CCFA agar) for isolation, not Thayer-Martin agar under aerobic conditions. *Hemolytic uremic syndrome* - Hemolytic uremic syndrome (HUS) is often caused by **Shiga toxin-producing *Escherichia coli* (STEC)**, particularly O157:H7. - STEC can be isolated on media like **sorbitol MacConkey agar (SMAC)**, where O157:H7 appears as non-sorbitol fermenting colonies, distinct from the growth seen on Thayer-Martin. *Oral thrush* - Oral thrush is caused by *Candida albicans*, a yeast. - *Candida* would be inhibited by **nystatin** in the Thayer-Martin medium, which is an antifungal agent.

Atypical US Medical PG Question 3: An 18-year old college freshman presents to his university clinic because he has not been feeling well for the past two weeks. He has had a persistent headache, occasional cough, and chills without rigors. The patient’s vital signs are normal and physical exam is unremarkable. His radiograph shows patchy interstitial lung infiltrates and he is diagnosed with atypical pneumonia. The patient is prescribed azithromycin and takes his medication as instructed. Despite adherence to his drug regimen, he returns to the clinic one week later because his symptoms have not improved. The organism responsible for this infection is likely resistant to azithromycin through which mechanism?

• A. Mutation in topoisomerase II
• B. Methylation of ribosomal binding site
• C. Presence of a beta-lactamase
• D. Decreased binding to RNA polymerase
• E. Insertion of drug efflux pumps (Correct Answer)

Atypical Explanation: ***Insertion of drug efflux pumps*** - **Azithromycin** is a macrolide antibiotic that inhibits bacterial protein synthesis by binding to the **50S ribosomal subunit**. - In **Mycoplasma pneumoniae** (the most common cause of atypical pneumonia in young adults), the **most common** mechanism of macrolide resistance is through **efflux pumps**, particularly the **mef genes**. - These efflux pumps actively transport macrolides out of the bacterial cell, reducing intracellular drug concentration and conferring resistance. - This mechanism is responsible for the majority of macrolide-resistant *M. pneumoniae* isolates worldwide. *Methylation of ribosomal binding site* - **Methylation** of the ribosomal binding site (specifically the **23S rRNA** via erm genes) does prevent azithromycin from binding effectively. - While this is a valid macrolide resistance mechanism seen in organisms like *Streptococcus pneumoniae* and *Streptococcus pyogenes*, it is **less common** in *Mycoplasma pneumoniae*. - Efflux pumps (mef) are the predominant mechanism in *M. pneumoniae* resistant strains. *Mutation in topoisomerase II* - **Topoisomerase II** (DNA gyrase) is the target of **fluoroquinolone antibiotics**, not macrolides. - Mutations in this enzyme lead to resistance against fluoroquinolones, such as **ciprofloxacin**. *Presence of a beta-lactamase* - **Beta-lactamase enzymes** inactivate **beta-lactam antibiotics** (e.g., penicillin, cephalosporins) by hydrolyzing their beta-lactam ring. - Additionally, *Mycoplasma pneumoniae* **lacks a cell wall**, making it inherently resistant to all beta-lactam antibiotics regardless of beta-lactamase production. *Decreased binding to RNA polymerase* - **RNA polymerase** is the target for antibiotics like **rifampin**, which inhibits bacterial transcription. - Decreased binding to RNA polymerase would lead to rifampin resistance, not azithromycin resistance.

Atypical US Medical PG Question 4: A 40-year-old man presents to the office complaining of chills, fever, and productive cough for the past 24 hours. He has a history of smoking since he was 18 years old. His vitals are: heart rate of 85/min, respiratory rate of 20/min, temperature 39.0°C (102.2°F), blood pressure 110/70 mm Hg. On physical examination, there is dullness on percussion on the upper right lobe, as well as bronchial breath sounds and egophony. The plain radiograph reveals an increase in density with an alveolar pattern in the upper right lobe. Which one is the most common etiologic agent of the suspected disease?

• A. Legionella pneumophila
• B. Chlamydia pneumoniae
• C. Mycoplasma pneumoniae
• D. Streptococcus pneumoniae (Correct Answer)
• E. Haemophilus influenzae

Atypical Explanation: ***Streptococcus pneumoniae*** - This patient presents with classic symptoms of **community-acquired pneumonia (CAP)**, including fever, chills, productive cough, and specific findings on physical exam (dullness, bronchial breath sounds, egophony) and chest X-ray (**lobar consolidation**). - **_Streptococcus pneumoniae_** is the most common bacterial cause of CAP worldwide, accounting for a significant percentage of cases, especially in adults. *Legionella pneumophila* - While _Legionella_ can cause severe pneumonia, it often presents with **GI symptoms** (diarrhea, nausea) and **neurological symptoms** (confusion) in addition to respiratory symptoms, which are not described here. - Risk factors typically include exposure to **contaminated water sources**, and the pneumonia can be rapidly progressive. *Chlamydia pneumoniae* - _Chlamydia pneumoniae_ typically causes a more **atypical pneumonia**, often with a more insidious onset, prolonged cough, and less severe systemic symptoms. - It usually presents as a **walking pneumonia** with milder findings on chest X-ray, unlike the clear lobar consolidation described. *Mycoplasma pneumoniae* - Like _Chlamydia pneumoniae_, _Mycoplasma pneumoniae_ is a common cause of **atypical pneumonia**, often with a gradual onset, hacking cough, and less pronounced fever. - It rarely causes the classic lobar consolidation seen in this patient and is often referred to as "walking pneumonia." *Haemophilus influenzae* - _Haemophilus influenzae_ is a significant cause of CAP, especially in patients with **underlying lung disease** (like COPD) or other comorbidities. - While certainly a possibility given the patient's smoking history, **_Streptococcus pneumoniae_** remains the overall most common cause of bacterial CAP in otherwise healthy adults.

Atypical US Medical PG Question 5: A patient is hospitalized for pneumonia. Gram-positive cocci in clusters are seen on sputum gram stain. Which of the following clinical scenarios is most commonly associated with this form of pneumonia?

• A. Elderly patient who has trouble swallowing and poor dentition
• B. An alcoholic with evidence of empyema and "currant jelly sputum"
• C. An otherwise healthy young adult with a week of mild fatigue, chills, and cough
• D. Hospitalized adult with development of pneumonia symptoms 2 weeks following a viral illness (Correct Answer)
• E. HIV positive adult with a CD4 count less than 150 and an impaired diffusion capacity

Atypical Explanation: ***Hospitalized adult with development of pneumonia symptoms 2 weeks following a viral illness*** - Gram-positive cocci in clusters suggests **Staphylococcus aureus**, which is a common cause of secondary bacterial pneumonia, often following **viral illnesses** (e.g., influenza). - This scenario represents a classic presentation of **secondary bacterial pneumonia**, where the initial viral infection compromises the respiratory defenses, allowing bacterial superinfection. *Elderly patient who has trouble swallowing and poor dentition* - This scenario points towards **aspiration pneumonia**, often caused by a **polymicrobial infection** that includes oral anaerobes, not typically dominated by Gram-positive cocci in clusters. - While *S. aureus* can cause aspiration pneumonia, the primary concern in this context would be **anaerobic bacteria**, given the aspiration risk factors. *An alcoholic with evidence of empyema and \"currant jelly sputum\"* - This description is highly suggestive of **Klebsiella pneumoniae** infection, which typically presents with thick, gelatinous, and often **blood-tinged sputum**. - **Klebsiella** is a Gram-negative rod, not Gram-positive cocci in clusters. *An otherwise healthy young adult with a week of mild fatigue, chills, and cough* - This presentation is more consistent with **atypical pneumonia** caused by organisms like **Mycoplasma pneumoniae** or **Chlamydophila pneumoniae**, which would not show Gram-positive cocci in clusters on sputum stain. - **Streptococcus pneumoniae** (Gram-positive cocci in chains) can also cause community-acquired pneumonia in otherwise healthy individuals, but the "clusters" indicate **Staphylococcus aureus**. *HIV positive adult with a CD4 count less than 150 and an impaired diffusion capacity* - This clinical picture strongly suggests **Pneumocystis jirovecii pneumonia (PJP)**, which is common in severely immunocompromised HIV patients. - *P. jirovecii* is a fungus and would not be seen as Gram-positive cocci in clusters on a routine Gram stain.

Atypical US Medical PG Question 6: A 62-year-old man is brought to the emergency department with fatigue, dry cough, and shortness of breath for 3 days. He reports a slight fever and has also had 3 episodes of watery diarrhea earlier that morning. Last week, he attended a business meeting at a hotel and notes some of his coworkers have also become sick. He has a history of hypertension and hyperlipidemia. He takes atorvastatin, hydrochlorothiazide, and lisinopril. He appears in mild distress. His temperature is 102.1°F (38.9°C), pulse is 56/min, respirations are 16/min, and blood pressure is 150/85 mm Hg. Diffuse crackles are heard in the thorax. Examination shows a soft and nontender abdomen. Laboratory studies show: Hemoglobin 13.5 g/dL Leukocyte count 15,000/mm3 Platelet count 130,000/mm3 Serum Na+ 129 mEq/L Cl- 100 mEq/L K+ 4.6 mEq/L HCO3- 22 mEq/L Urea nitrogen 14 mg/dL Creatinine 1.3 mg/dL An x-ray of the chest shows infiltrates in both lungs. Which of the following is the most appropriate next step in diagnosis?

• A. Urine antigen assay (Correct Answer)
• B. CT Chest
• C. Direct immunofluorescent antibody test
• D. Stool culture
• E. Polymerase chain reaction

Atypical Explanation: ***Urine antigen assay*** - This patient presents with **pneumonia symptoms** (low-grade fever, dry cough, dyspnea, bilateral infiltrates) along with **gastrointestinal symptoms** (watery diarrhea) and **hyponatremia**, after attending a hotel meeting with other sick attendees. These are classic features of **Legionnaires' disease**. - A **urine antigen assay** is a rapid and highly specific test for **Legionella pneumophila serogroup 1**, which causes the majority of Legionnaires' disease cases. *CT Chest* - A CT scan of the chest would provide more detailed imaging of the lung infiltrates but is typically used to characterize findings once pneumonia is diagnosed or to rule out other lung pathologies, not as an initial diagnostic test for the specific pathogen. - While it can reveal characteristic patterns, it doesn't identify the causative organism and is not the most appropriate *next step in diagnosis* for a presumed Legionella infection. *Direct immunofluorescent antibody test* - A **direct immunofluorescent antibody (DFA) test** is used to identify legionella in respiratory secretions. However, collecting a sufficiently good sputum sample can be difficult, especially with a **dry cough**. - Its sensitivity is lower than urine antigen testing for serogroup 1 and requires a respiratory sample, making it less convenient for initial diagnosis. *Stool culture* - While the patient has diarrhea, a **stool culture** would primarily detect typical bacterial enteric pathogens (e.g., Salmonella, Shigella, Campylobacter) and would not identify **Legionella**. - The diarrhea, in this context, is likely an extrapulmonary manifestation of Legionnaires' disease caused by Legionella, not a separate primary enteric infection. *Polymerase chain reaction* - **PCR testing** can detect Legionella DNA in respiratory samples, offering high sensitivity and specificity. - However, it is generally less rapid and widely available than the urine antigen test for initial diagnosis of Legionella pneumophila serogroup 1, which is the most common cause of Legionnaires' disease.

Atypical US Medical PG Question 7: A previously healthy 24-year-old woman comes to the physician because of a 1-day history of nausea and weakness. She is sexually active with 2 male partners and uses an oral contraceptive; she uses condoms inconsistently. Her last menstrual period was 4 days ago. Her temperature is 38.4°C (101°F). Physical examination shows right costovertebral angle tenderness. Pelvic examination is normal. Which of the following is the most likely cause of this patient's condition?

• A. Noninfectious inflammation of the bladder
• B. Ascending bacteria from the endocervix
• C. Decreased renal calcium reabsorption
• D. Decreased urinary pH
• E. Ascending bacteria from the bladder (Correct Answer)

Atypical Explanation: ***Ascending bacteria from the bladder*** - The patient presents with **fever**, **nausea**, **weakness**, and **right costovertebral angle (CVA) tenderness**, which are classic symptoms of **acute pyelonephritis**. - **Pyelonephritis** most commonly results from an **ascending urinary tract infection**, where bacteria (typically *E. coli*) from the bladder travel up the ureters to infect the kidneys. - This accounts for approximately **95% of pyelonephritis cases** in young women. *Noninfectious inflammation of the bladder* - **Noninfectious cystitis** (interstitial cystitis) would not typically present with systemic symptoms like **fever** and **nausea**, or with **CVA tenderness**, which indicates kidney involvement. - Bladder inflammation typically causes dysuria and frequency without systemic signs of infection. *Ascending bacteria from the endocervix* - **Ascending bacteria from the endocervix** can cause **pelvic inflammatory disease (PID)**, which presents with lower abdominal pain, cervical motion tenderness, and vaginal discharge. - While PID can cause fever, the **normal pelvic examination** in this patient rules out this diagnosis, and PID **does not typically cause CVA tenderness**. *Decreased renal calcium reabsorption* - **Decreased renal calcium reabsorption** is associated with **hypercalciuria** and **nephrolithiasis** (kidney stones), which can present with acute flank pain if obstruction occurs. - However, this condition does not explain the **fever** and systemic symptoms characteristic of an acute infectious process. *Decreased urinary pH* - **Decreased urinary pH** (acidic urine) can predispose to certain types of kidney stone formation but is not a direct cause of **pyelonephritis**. - It does not explain the presence of **fever**, **CVA tenderness**, and systemic symptoms indicative of a bacterial kidney infection.

Atypical US Medical PG Question 8: A 16-year-old female presents to her pediatrician complaining of 2 weeks of fever and 1 week of swollen lumps in her left armpit. Upon examination of the left upper extremity, her physician notes the presence of a single papule which the patient claimed appeared one week ago. The patient started her first job at a pet store 2.5 weeks ago. Which of the following is the vector of transmission of the causative agent?

• A. Cats (Correct Answer)
• B. Rabbits
• C. Animal urine
• D. Parrots
• E. Armadillos

Atypical Explanation: ***Cats*** - The combination of **fever**, **swollen lymph nodes** (lumps in the armpit), a **single papule**, and a recent history of working at a **pet store** strongly suggests **cat scratch disease**. - **Cat scratch disease** is caused by *Bartonella henselae*, which is primarily transmitted to humans through the **scratch or bite of a cat**, especially kittens. *Rabbits* - Rabbits are known vectors for diseases like **tularemia**, which can cause fever and swollen lymph nodes. - However, the typical presentation of tularemia often includes a more prominent **ulcerative lesion** at the site of inoculation, and the papule described is less characteristic. *Animal urine* - While animal urine can transmit diseases like **leptospirosis**, which can cause fever and various systemic symptoms, it typically does not present with a localized papule followed by regional lymphadenopathy in this manner. - Exposure to animal urine usually occurs through contact with contaminated water or soil, and the pet store context points more towards direct animal contact. *Parrots* - Parrots are associated with **psittacosis** (parrot fever), caused by *Chlamydia psittaci*. - Psittacosis primarily manifests as a **respiratory illness** (pneumonia) and does not typically present with a localized papule and regional lymphadenopathy. *Armadillos* - Armadillos are significant reservoirs for **Mycobacterium leprae**, the causative agent of **leprosy**. - Leprosy has a very long incubation period and presents with skin lesions, nerve damage, and sometimes lymphadenopathy, but a 2-week onset and the described acute symptoms are inconsistent with leprosy.

Atypical US Medical PG Question 9: A 32-year-old woman comes to the emergency department with a 2-day history of abdominal pain and diarrhea. She has had about 8 voluminous stools per day, some of which were bloody. She visited an international food festival three days ago. She takes no medications. Her temperature is 39.5°C (103.1°F), pulse is 90/min, and blood pressure is 110/65 mm Hg. Examination shows a tender abdomen, increased bowel sounds, and dry mucous membranes. Microscopic examination of the stool shows polymorphonuclear leukocytes. Stool culture results are pending. Which of the following most likely caused the patient's symptoms?

• A. Home-canned vegetables
• B. Yogurt dip
• C. Reheated rice
• D. Toxic mushrooms
• E. Omelette (Correct Answer)

Atypical Explanation: **Omelette** - The symptoms, including **bloody diarrhea**, fever, and exposure to an international food festival suggest a **bacterial infection**, likely from contaminated eggs (e.g., **Salmonella**). - The presence of **polymorphonuclear leukocytes** in the stool indicates an **invasive bacterial infection**, consistent with salmonellosis. *Home-canned vegetables* - Poorly preserved home-canned vegetables are a classic cause of **botulism**, which presents with **neurological symptoms** (e.g., flaccid paralysis) and is not characterized by bloody diarrhea or fever. - While it can cause gastrointestinal upset, bloody stools are not typical, and the primary concern is neurotoxicity due to **Clostridium botulinum toxin**. *Yogurt dip* - Yogurt is a dairy product, and contamination typically leads to **non-bloody diarrhea** and vomiting, often caused by bacteria like *Staphylococcus aureus* or *Bacillus cereus* producing enterotoxins. - The symptoms would likely be less severe and lack the invasive features (bloody stools, fever, PMNs) seen in this patient. *Reheated rice* - Reheated rice is commonly associated with **Bacillus cereus** food poisoning, which typically causes either an emetic (vomiting) or diarrheal syndrome. - The diarrhea caused by *Bacillus cereus* is usually **watery and non-bloody**, and it rarely presents with significant fever or invasive features like polymorphonuclear leukocytes in stool. *Toxic mushrooms* - Mushroom poisoning can present with a wide range of symptoms, including gastrointestinal distress (vomiting, diarrhea), but the presentation varies greatly depending on the mushroom species. - **Bloody diarrhea** with fever and polymorphonuclear leukocytes in stool is not a typical hallmark of common toxic mushroom ingestions, which often involve hepatotoxicity or neurotoxicity.

Atypical US Medical PG Question 10: A 69-year-old man is brought to the emergency department by his wife because of fever, cough, diarrhea, and confusion for 2 days. He recently returned from a cruise to the Caribbean. He has a history of chronic obstructive pulmonary disease. He has smoked one pack of cigarettes daily for 40 years. His temperature is 39.1°C (102.4°F), pulse is 83/min, and blood pressure is 111/65 mm Hg. He is confused and oriented only to person. Physical examination shows coarse crackles throughout both lung fields. His serum sodium concentration is 125 mEq/L. Culture of the most likely causal organism would require which of the following mediums?

• A. Charcoal yeast extract agar (Correct Answer)
• B. Eosin-methylene blue agar
• C. Mannitol salt agar
• D. Chocolate agar
• E. Eaton agar

Atypical Explanation: ***Charcoal yeast extract agar*** - The patient's symptoms (fever, cough, diarrhea, confusion, hyponatremia) and risk factors (COPD, smoking history, recent cruise travel) are highly suggestive of **Legionnaires' disease** caused by *Legionella pneumophila*. - *Legionella* is a fastidious organism that requires **cysteine** and **iron salts** for growth, which are provided in **buffered charcoal yeast extract (BCYE) agar**. *Eosin-methylene blue agar* - This is a **selective and differential medium** used for the isolation and differentiation of **Gram-negative enteric bacteria**, particularly useful for identifying coliforms like *E. coli*. - It contains dyes that inhibit Gram-positive bacteria and differentiate lactose fermenters, which is not relevant for *Legionella*. *Mannitol salt agar* - This is a **selective and differential medium** primarily used for the isolation and identification of **staphylococci**, especially *Staphylococcus aureus*. - It contains a high salt concentration to inhibit most bacteria and mannitol to differentiate *S. aureus* (which ferments mannitol) from other staphylococci. *Chocolate agar* - This enriched medium is used for the isolation of fastidious bacteria such as **Haemophilus influenzae** and **Neisseria species**, which require factors like **hemin (X factor)** and **NAD (V factor)**. - While it supports the growth of many pathogenic bacteria, it does not provide the specific growth requirements for *Legionella*. *Eaton agar* - This specialized medium is primarily used for the isolation and cultivation of **Mycoplasma pneumoniae**, a common cause of "walking pneumonia." - *Mycoplasma pneumoniae* is a bacterium that lacks a cell wall and has unique growth requirements, distinct from *Legionella*.

Atypical Flashcard 1 of 10

Question: _____ is a Rickettsial disease that can be obtained via aerosolized spores released from tick feces or cattle placenta.

Answer: Q Fever

Atypical Flashcard 2 of 10

Question: What is the definitive test for diagnosing Legionnaires' disease (Legionella pneumophila)?_____

Answer: Sputum culture

Atypical Flashcard 3 of 10

Question: What culture is used to grow Mycoplasma pneumoniae?_____

Answer: Eaton agar

Atypical Flashcard 4 of 10

Question: Rocky mountain spotted fever = _____

Answer: Rickettsia rickettsii

Extra Information:  https://onlinemeded.org/spa/infectious-disease?ref=anki 

Atypical Flashcard 5 of 10

Question: Due to Chlamydia spp. being obligate intracellular bacteria, they gram stain _____

Answer: poorly

Extra Information:   Watch Chlamydia trachomatis, Chlamydophila pneumoniae & Chlamydophila psittaci [https://dashboard.sketchy.com/study/medical/courses/medical-microbiology/units/medical-microbiology-bacteria/videos/medical-microbiology-bacteria-gram-indeterminate-bacteria-chlamydia-trachomatis-chlamydophila-pneumoniae-and-chlamydophila-psittaci?utm_source=anki&utm_medium=partnership&utm_campaign=february_update&utm_content=medical]Watch associated Bootcamp video [https://app.bootcamp.com/med-school/microbiology/videos/fundamentals-of-bacteriology?index=4] https://onlinemeded.org/spa/infectious-disease?ref=anki 

Atypical Flashcard 6 of 10

Question: What is the most common cause of pneumonia in individuals living in close quarters?_____

Answer: Mycoplasma pneumoniae

Atypical Flashcard 7 of 10

Question: Mycoplasma pneumoniae

Answer:

Extra Information: Eaton's agaratypical "walking" pneumoniamacrolide or flouroquinolone

Atypical Flashcard 8 of 10

Question: What are the key associations to remember for cold agglutinin?

Answer: IgM, Mycoplasma, Mononucleosis (EBV)

Atypical Flashcard 9 of 10

Question: Mycoplasmal pneumonia

Answer: Mycoplasma pneumoniae

Extra Information: pneumonia with insidious onset, headache, nonproductive cough, diffuse interstitial infiltratelung X-ray: diffuse interstitial inflitratemacrolide or flouroquinolone<30 y/o, military recruits and prisoners

Atypical Flashcard 10 of 10

Question: What factor explains Mycoplasma's inability to Gram stain?

Answer: no cell wall!