Normal flora

Normal flora US Medical PG Question 1: A medical student is reading about a specific type of T cells that plays an important role in immunologic tolerance. Most of these cells develop in the thymus, but some of them also develop in peripheral lymphoid organs. Usually, they are CD4+ cells and also express CD25 molecules. The functions of these cells are dependent on forkhead box P3 (Foxp3). Their function is to block the activation of lymphocytes that could react with self-antigens in a potentially harmful manner. Which of the following interleukins is secreted by these cells?

• A. Interleukin-6
• B. Interleukin-10 (Correct Answer)
• C. Interleukin-2
• D. Interleukin-12
• E. Interleukin-17

Normal flora Explanation: ***Interleukin-10*** - The description points to **regulatory T cells (Tregs)**, which are CD4+, CD25+, and Foxp3+. A key function of Tregs in maintaining **immunologic tolerance** is the secretion of **IL-10** and TGF-β. - **IL-10** is a potent **anti-inflammatory cytokine** that suppresses the activation and proliferation of various immune cells, including T cells, macrophages, and dendritic cells, thereby preventing immune responses against self-antigens. *Interleukin-6* - **IL-6** is a **pro-inflammatory cytokine** primarily involved in the acute phase response, hematopoiesis, and differentiation of Th17 cells, which is contrary to the immunosuppressive role of Tregs. - It promotes inflammation and is secreted by various cells, including macrophages, T cells, and B cells, but not typically by Tregs as part of their suppressive function. *Interleukin-2* - **IL-2** is an important **T cell growth factor**, crucial for the proliferation and differentiation of T cells, including Tregs themselves, but it is primarily secreted by activated helper T cells (Th1). - While Tregs express the **CD25 (IL-2 receptor alpha chain)** and require IL-2 for their survival and function, they do not typically secrete IL-2 as their primary immunomodulatory cytokine. *Interleukin-12* - **IL-12** is a cytokine mainly produced by antigen-presenting cells (APCs) like dendritic cells and macrophages, and plays a critical role in promoting **Th1 differentiation** and cell-mediated immunity. - It is a **pro-inflammatory cytokine** that drives immune responses, which is opposite to the suppressive function described for these cells. *Interleukin-17* - **IL-17** is the signature cytokine of **Th17 cells**, which are primarily involved in host defense against extracellular bacteria and fungi, but also play a significant role in mediating autoimmune diseases. - It is a **pro-inflammatory cytokine** and its production is antagonistic to the immunosuppressive function of regulatory T cells.

Normal flora US Medical PG Question 2: A 24-year-old man, an information technology professional, gets himself tested for serum immunoglobulin M (IgM) levels because he wants to know more about his immunity. He knows that IgM levels reflect the status of his immunity, based on the internet. Although the laboratory report is normal, he consults a physician. The physician discusses human immunity and its important components. He also tells him that most circulating IgM antibodies in the blood of normal persons are produced by a specific type of B cell, which is present mostly in the peritoneal cavity and in mucosal tissues. He also mentions that these cells are components of innate immunity. Which of the following types of B cells is the physician referring to?

• A. Naïve B cells
• B. Marginal zone B cells
• C. Follicular B cells
• D. B-1 B cells (Correct Answer)

Normal flora Explanation: ***B-1 B cells*** - **B-1 B cells** are a distinct lymphocyte population found primarily in the **peritoneal and pleural cavities**, and mucosal tissues. They spontaneously secrete **IgM antibodies** without T cell help, which are important for initial defense against common pathogens. - They are considered a component of the **innate immune system** due to their rapid, T-cell-independent response and limited receptor diversity, providing immediate protection. *Naïve B cells* - **Naïve B cells** circulate in the blood and secondary lymphoid organs, express both **IgM and IgD** on their surface, and have not yet encountered their specific antigen. - They require activation by antigen and often **T cell help** to differentiate into plasma cells and produce antibodies. *Marginal zone B cells* - **Marginal zone (MZ) B cells** are located in the marginal zone of the spleen and respond rapidly to **blood-borne polysaccharide antigens**. - While they can produce **IgM without T-cell help**, they are primarily found in the spleen, not predominantly the peritoneal cavity or mucosal tissues. *Follicular B cells* - **Follicular B cells** are the most abundant B cell population in secondary lymphoid organs, residing in **B cell follicles**. - They require **T cell help** to mount robust immune responses, undergo class-switching, and affinity maturation, and are not primarily known for spontaneous IgM production in the peritoneal cavity.

Normal flora US Medical PG Question 3: A 37-year-old woman with a history of anorectal abscesses complains of pain in the perianal region. Physical examination reveals mild swelling, tenderness, and erythema of the perianal skin. She is prescribed oral ampicillin and asked to return for follow-up. Two days later, the patient presents with a high-grade fever, syncope, and increased swelling. Which of the following would be the most common mechanism of resistance leading to the failure of antibiotic therapy in this patient?

• A. Intrinsic absence of a target site for the drug
• B. Use of an altered metabolic pathway
• C. Production of beta-lactamase enzyme (Correct Answer)
• D. Altered structural target for the drug
• E. Drug efflux pump

Normal flora Explanation: ***Production of beta-lactamase enzyme*** - The patient's symptoms of a rapidly worsening infection despite ampicillin treatment suggest the presence of a **beta-lactamase producing organism**. Ampicillin is a **beta-lactam antibiotic** that is inactivated by these enzymes. - Anorectal abscesses and rapidly progressing soft tissue infections are often caused by **polymicrobial flora**, including staphylococci and enterococci, many of which can produce **beta-lactamase**. *Intrinsic absence of a target site for the drug* - While some bacteria inherently lack the target site for certain drugs (e.g., mycoplasma lacking a cell wall, thus being resistant to beta-lactams), this is less likely to be the **most common mechanism of acquired resistance** leading to treatment failure in a typical perianal infection. - The rapid progression and failed initial treatment point towards an **acquired mechanism of resistance** rather than an intrinsic one. *Use of an altered metabolic pathway* - This mechanism, such as altered **folate synthesis pathways** in resistance to trimethoprim-sulfamethoxazole, is less common as the primary mechanism for ampicillin resistance. - Ampicillin's mechanism of action primarily targets the **bacterial cell wall**, not a metabolic pathway in the same way. *Altered structural target for the drug* - This involves modifications to the **penicillin-binding proteins (PBPs)**, which are the targets of beta-lactam antibiotics like ampicillin. While a valid mechanism (e.g., in MRSA), the **production of beta-lactamase** is generally a more widespread and common cause of ampicillin failure, especially in infections involving mixed flora from the perianal region. - Given the abrupt failure of ampicillin, **beta-lactamase inactivation** is a more immediate and common cause than a rapid mutational change in PBPs. *Drug efflux pump* - **Efflux pumps** actively remove antibiotics from the bacterial cell, contributing to resistance against various drug classes. - While efflux pumps can play a role, the dominant mechanism for resistance to **ampicillin** in many common perianal pathogens is the **enzymatic degradation by beta-lactamases**.

Normal flora US Medical PG Question 4: 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)

Normal flora 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.

Normal flora US Medical PG Question 5: A team of intensivists working in a private intensive care unit (ICU) observe that the clinical efficacy of vancomycin is low, and proven nosocomial infections have increased progressively over the past year. A clinical microbiologist is invited to conduct a bacteriological audit of the ICU. He analyzes the microbiological reports of all patients treated with vancomycin over the last 2 years and takes relevant samples from the ICU for culture and antibiotic sensitivity analysis. The audit concludes that there is an increased incidence of vancomycin-resistant Enterococcus fecalis infections. Which of the following mechanisms best explains the changes that took place in the bacteria?

• A. Decreased number of porins in the bacterial cell wall leading to decreased intracellular entry of the antibiotic
• B. Production of an enzyme that hydrolyzes the antibiotic
• C. Protection of the antibiotic-binding site by Qnr protein
• D. Increased expression of efflux pumps which extrude the antibiotic from the bacterial cell
• E. Replacement of the terminal D-Ala in the cell wall peptidoglycan by D-lactate (Correct Answer)

Normal flora Explanation: ***Replacement of the terminal D-ala in the cell wall peptidoglycan by D-lactate*** - **Vancomycin** exerts its antibacterial effect by binding to the **D-Ala-D-Ala** terminus of the peptidoglycan precursor in the bacterial cell wall, preventing its incorporation. - In **vancomycin-resistant Enterococcus (VRE)**, the D-Ala-D-Ala is replaced by **D-Ala-D-Lac**, which significantly reduces vancomycin's binding affinity, leading to resistance. *Decreased number of porins in the bacterial cell wall leading to decreased intracellular entry of the antibiotic* - This mechanism primarily affects **Gram-negative bacteria**, where porins are crucial for antibiotic entry through the outer membrane. - **Enterococcus faecalis** is a **Gram-positive bacterium** and does not rely on porins in the same way for vancomycin uptake. *Production of an enzyme that hydrolyzes the antibiotic* - This mechanism is characteristic of resistance to **beta-lactam antibiotics** (e.g., penicillinases, cephalosporinases). - Vancomycin is not a beta-lactam, and its resistance mechanism in Enterococcus does not typically involve enzymatic hydrolysis. *Protection of the antibiotic-binding site by Qnr protein* - **Qnr proteins** are associated with **quinolone resistance**, specifically by protecting DNA gyrase and topoisomerase IV from quinolone inhibition. - This mechanism is irrelevant to vancomycin, which targets the bacterial cell wall. *Increased expression of efflux pumps which extrude the antibiotic from the bacterial cell* - Efflux pumps are a common mechanism of antibiotic resistance against a wide range of antibiotics, including **tetracyclines, macrolides, and fluoroquinolones**. - While efflux pumps can contribute to some forms of resistance, they are not the primary or best-explained mechanism for **high-level vancomycin resistance in Enterococcus**.

Normal flora US Medical PG Question 6: A 24-year-old woman presents to the ED with symptoms of pelvic inflammatory disease despite being previously treated with azithromycin for chlamydial infection. Based on your clinical understanding about the epidemiology of PID, you decide to obtain a gram stain which shows a gram-negative diplococci. What is the next step in order to confirm the identity of the organism described?

• A. Perform an RT-PCR
• B. Culture in TCBS agar
• C. Culture in Thayer-Martin media (Correct Answer)
• D. Obtain an acid fast stain
• E. Culture in Bordet-Gengou agar

Normal flora Explanation: ***Culture in Thayer-Martin media*** - The presence of **gram-negative diplococci** in a patient with PID symptoms strongly suggests *Neisseria gonorrhoeae*. - **Thayer-Martin media** is a selective **agar** specifically designed for the isolation and identification of *Neisseria* species, including *N. gonorrhoeae*, by inhibiting the growth of most commensal bacteria and fungi. *Perform an RT-PCR* - While **RT-PCR** can detect *Neisseria gonorrhoeae* nucleic acids, it is primarily used for **molecular diagnosis** and not directly for confirming the identity of a cultured organism visualized on gram stain. - **RT-PCR** is generally used for direct detection from clinical samples and is particularly useful in situations where culture is difficult or unavailable. *Culture in TCBS agar* - **TCBS (Thiosulfate Citrate Bile Salts Sucrose) agar** is a selective medium primarily used for the isolation of *Vibrio* species, which are not typically associated with pelvic inflammatory disease or characterized as gram-negative diplococci. - This medium is designed to differentiate between different *Vibrio* species based on sucrose fermentation. *Obtain an acid fast stain* - An **acid-fast stain** (e.g., Ziehl-Neelsen stain) is used to identify bacteria with a **waxy cell wall**, such as *Mycobacterium* species (e.g., *Mycobacterium tuberculosis*). - *Neisseria gonorrhoeae* is not acid-fast, and this stain would not be appropriate for its identification. *Culture in Bordet-Gengou agar* - **Bordet-Gengou agar** is a specialized culture medium used for the isolation of *Bordetella pertussis*, the causative agent of whooping cough. - This medium is not suitable for the isolation of *Neisseria gonorrhoeae*.

Normal flora US Medical PG Question 7: A 61-year-old woman comes to the physician because of a 5-day history of fever, headache, coughing, and thick nasal discharge. She had a sore throat and nasal congestion the week before that had initially improved. Her temperature is 38.1°C (100.6°F). Physical exam shows purulent nasal drainage and tenderness to percussion over the frontal sinuses. The nasal turbinates are erythematous and mildly swollen. Which of the following describes the microbiological properties of the most likely causal organism?

• A. Gram-positive, anaerobic, non-acid fast branching filamentous bacilli
• B. Gram-negative, lactose-nonfermenting, blue-green pigment-producing bacilli
• C. Gram-positive, optochin-sensitive, lancet-shaped diplococci (Correct Answer)
• D. Gram-negative, oxidase-positive, maltose-nonfermenting diplococci
• E. Gram-positive, coagulase-positive, clustered cocci

Normal flora Explanation: ***Gram-positive, optochin-sensitive, lancet-shaped diplococci*** - The patient's symptoms (fever, headache, purulent nasal discharge, sinus tenderness, and erythematous nasal turbinates following a viral URI) are highly suggestive of **acute bacterial rhinosinusitis**. - The most common bacterial cause of acute bacterial rhinosinusitis is *Streptococcus pneumoniae*, which is characterized as **Gram-positive, lancet-shaped diplococci** that are **optochin-sensitive** and alpha-hemolytic. *Gram-positive, anaerobic, non-acid fast branching filamentous bacilli* - This describes organisms like *Actinomyces israelii*, which typically cause chronic infections like **actinomycosis** with abscess formation and draining sinuses, not acute rhinosinusitis. - *Actinomyces* infections are often associated with trauma, surgery, or poor oral hygiene, which is not indicated here. *Gram-negative, lactose-nonfermenting, blue-green pigment-producing bacilli* - These characteristics describe *Pseudomonas aeruginosa*, which can cause sinusitis, but typically in immunocompromised individuals, those with cystic fibrosis, or following nosocomial infections, and is less common as an initial cause of acute community-acquired rhinosinusitis. - *Pseudomonas* sinusitis often involves more severe, systemic symptoms or chronic infections. *Gram-negative, oxidase-positive, maltose-nonfermenting diplococci* - These properties describe *Neisseria gonorrhoeae* or *Neisseria meningitidis*, neither of which are common causes of acute bacterial rhinosinusitis. - *Neisseria* species primarily cause sexually transmitted infections (gonorrhea) or meningitis, respectively. *Gram-positive, coagulase-positive, clustered cocci* - This describes *Staphylococcus aureus*, which is another common cause of acute bacterial rhinosinusitis. - While *S. aureus* can certainly cause sinusitis, *Streptococcus pneumoniae* is generally considered the most frequent bacterial pathogen in community-acquired cases.

Normal flora US Medical PG Question 8: A 19-year-old female presents with a malodorous vaginal discharge. She notes that the odor is more prominent after sexual intercourse. She is sexually active with one partner and uses barrier contraception. Her past medical history is significant only for community-acquired pneumonia treated with antibiotics 2 months ago. The vital signs were as follows: blood pressure, 110/70 mm Hg; heart rate, 68/min; respiratory rate, 12/min; and temperature, 36.6℃ (97.9℉). The physical examination was normal. On gynecologic examination, the vaginal walls and cervix appeared normal. There was a gray, thin, homogeneous discharge with bubbles. The pH of the discharge was approximately 6.0. Which of the following findings would be expected on further investigation of this patient?

• A. Numerous gram-positive rod-shaped bacteria on Gram stain
• B. Bacteria-coated epithelial cells on wet mount microscopy (Correct Answer)
• C. Gram-positive diplococci on Gram stain
• D. Negative whiff test
• E. Motile protozoa on wet mount microscopy

Normal flora Explanation: ***Bacteria-coated epithelial cells on wet mount microscopy*** - This finding, specifically **clue cells**, is a hallmark of **bacterial vaginosis (BV)**. Clue cells are vaginal epithelial cells covered in bacteria, indicating the overgrowth of anaerobic bacteria and a decrease in normal lactobacilli. - The patient's symptoms of a **malodorous discharge** that worsens after intercourse, a **gray, thin, homogeneous discharge**, and a **vaginal pH of 6.0** are all classic signs of bacterial vaginosis. *Numerous gram-positive rod-shaped bacteria on Gram stain* - **Normal vaginal flora** is dominated by **Gram-positive rods (lactobacilli)**. In bacterial vaginosis, these beneficial bacteria are significantly reduced, while anaerobic bacteria proliferate. - An overgrowth of Gram-positive rods would suggest a healthy vaginal flora, conflicting with the presented symptoms and a high vaginal pH. *Gram-positive diplococci on Gram stain* - **Gram-positive diplococci** isolated from vaginal discharge could suggest an infection with organisms like **Streptococcus pneumoniae** or **Staphylococcus aureus**, which are not typical causes of malodorous vaginal discharge or bacterial vaginosis. - Infections like Neisseria gonorrhoeae, which can cause cervicitis, are characterized by **Gram-negative diplococci**. *Negative whiff test* - The **whiff test** involves adding potassium hydroxide (KOH) to vaginal discharge to detect a fishy odor. A **positive whiff test** is a characteristic sign of bacterial vaginosis due to the production of amines by anaerobic bacteria. - A negative whiff test would argue against a diagnosis of bacterial vaginosis despite the other clinical findings. *Motile protozoa on wet mount microscopy* - The presence of **motile protozoa**, specifically **Trichomonas vaginalis**, is indicative of trichomoniasis, another common cause of vaginitis. - While trichomoniasis can cause a frothy discharge and elevated pH, the discharge is often described as greenish-yellow, and it would not typically present with the specific features of clue cells.

Normal flora US Medical PG Question 9: A 38-year-old, working, first-time mother brings her 9-month-old male infant to the pediatrician for "wounds that simply won't heal" and bleeding gums. She exclaims, "I have been extra careful with him making sure to not let him get dirty, I boil his baby formula for 15 minutes each morning before I leave for work to give to the caregiver, and he has gotten all of his vaccinations." This infant is deficient in a molecule that is also an essential co-factor for which of the following reactions?

• A. Conversion of homocysteine to methionine
• B. Conversion of alpha ketoglutarate to succinyl-CoA
• C. Conversion of dopamine to norepinephrine (Correct Answer)
• D. Conversion of pyruvate to acetyl-CoA
• E. Conversion of pyruvate to oxaloacetate

Normal flora Explanation: ***Conversion of dopamine to norepinephrine*** - The infant's symptoms of "wounds that simply won't heal" and **bleeding gums** are classic signs of **scurvy**, caused by a deficiency in **vitamin C (ascorbic acid)**. - **Vitamin C** is an essential cofactor for **dopamine beta-hydroxylase**, the enzyme responsible for converting **dopamine to norepinephrine**. *Conversion of homocysteine to methionine* - This reaction is catalyzed by **methionine synthase**, which requires **vitamin B12** (cobalamin) and **folate (vitamin B9)** as cofactors. - Deficiency in these vitamins would lead to **megaloblastic anemia** and neurological symptoms, not delayed wound healing and bleeding gums. *Conversion of alpha ketoglutarate to succinyl-CoA* - This step in the **Krebs cycle** is catalyzed by **alpha-ketoglutarate dehydrogenase**, which requires **thiamine (vitamin B1)**, **lipoic acid**, **Mg2+**, **NAD+**, and **FAD** as cofactors. - Thiamine deficiency can cause **beriberi** or **Wernicke-Korsakoff syndrome**, not scurvy symptoms. *Conversion of pyruvate to acetyl-CoA* - This reaction is catalyzed by the **pyruvate dehydrogenase complex**, which requires **thiamine (vitamin B1)**, **lipoic acid**, **coenzyme A**, **FAD**, and **NAD+** as cofactors. - A deficiency in any of these, particularly thiamine, leads to impaired carbohydrate metabolism and lactic acidosis. *Conversion of pyruvate to oxaloacetate* - This reaction is catalyzed by **pyruvate carboxylase**, which requires **biotin (vitamin B7)** as a cofactor and is essential for **gluconeogenesis**. - Biotin deficiency is rare and can present with dermatitis, hair loss, and neurological symptoms, not the classic signs of scurvy.

Normal flora US Medical PG Question 10: While testing various strains of Streptococcus pneumoniae, a researcher discovers that a certain strain of this bacteria is unable to cause disease in mice when deposited in their lungs. What physiological test would most likely deviate from normal in this strain of bacteria as opposed to a typical strain?

• A. Quellung reaction (Correct Answer)
• B. Hemolytic reaction when grown on sheep blood agar
• C. Bile solubility
• D. Optochin sensitivity
• E. Motility

Normal flora Explanation: ***Quellung reaction*** - The **Quellung reaction** tests for the presence of the **polysaccharide capsule**, which is the primary virulence factor of *S. pneumoniae*. - An **avirulent strain** that cannot cause disease would most likely lack the capsule and show a **negative Quellung reaction** (no capsular swelling), deviating from the **positive reaction** seen in typical encapsulated pathogenic strains. - The capsule enables *S. pneumoniae* to evade phagocytosis and complement-mediated killing, which is essential for establishing infection in the lungs. *Hemolytic reaction when grown on sheep blood agar* - Both virulent and avirulent strains of *S. pneumoniae* typically exhibit **alpha-hemolysis** (partial hemolysis, producing a greenish discoloration) on sheep blood agar due to the production of pneumolysin. - This characteristic does not differentiate between pathogenic and non-pathogenic strains in terms of disease-causing ability. *Bile solubility* - *S. pneumoniae* is characteristically **bile-soluble** due to the presence of autolysin enzymes that are activated by bile salts, leading to cellular lysis. - This property is a **species characteristic** present in both virulent and avirulent strains, thus it would not explain the inability to cause disease. *Optochin sensitivity* - *S. pneumoniae* is universally **sensitive to optochin**, a chemical agent that inhibits its growth and is used for laboratory identification. - This characteristic is used for **species identification** but does not correlate with strain virulence or disease-causing ability. *Motility* - *Streptococcus pneumoniae* is a **non-motile** bacterium; it lacks flagella. - This characteristic is consistent across all strains and is not a virulence factor for this species.

Normal flora Flashcard 1 of 6

Question: _____ lack the enzymes Superoxide Dismutase and Catalase

Answer: Obligate Anaerobes (Obligate Aerobes or Anaerobes)

Normal flora Flashcard 2 of 6

Question: Which bacteria is normal flora of the vagina?_____

Answer: Lactobacillus

Normal flora Flashcard 3 of 6

Question: Which bacteria is seen cultured from the vagina below?_____

Answer: Gardnerella vaginalisepithelial cell covered with bacteria (clue cell)

Normal flora Flashcard 4 of 6

Question: Gram Negative Algorithm:Diplococci are _____ organisms

Answer: aerobic (aerobic/anaerobic)

Normal flora Flashcard 5 of 6

Question: In which type of immunity (innate or adaptive) does microbial resistance persist through generations?_____

Answer: Innate immunity

Normal flora Flashcard 6 of 6

Question: Describe the characteristic appearance of microglia.

Answer: small irregular nuclei and sparse cytoplasm mnemonic: microglia have mico-nuclei and micro-cytoplasm