Bacteria

Bacteria US Medical PG Question 1: A 42-year-old woman comes to her primary care physician with 2 days of fever and malaise. She also says that she has a painful red lesion on her left hand that she noticed after shucking oysters at a recent family reunion. Physical exam reveals a well-demarcated swollen, tender, warm, red lesion on her left hand. Pressing the lesion causes a small amount of purulent drainage. The material is cultured and the causative organism is identified. Which of the following characteristics describes the organism that is most associated with this patient's mechanism of infection?

• A. Gram-negative facultative anaerobe (Correct Answer)
• B. Gram-negative aerobe
• C. Gram-positive clusters
• D. Gram-positive chains
• E. Gram-negative anaerobe

Bacteria Explanation: ***Gram-negative facultative anaerobe*** - This clinical presentation, including oyster exposure and a painful, red hand lesion with purulent drainage, is highly suggestive of infection with **Vibrio vulnificus**. - **Vibrio vulnificus** is a classic **Gram-negative facultative anaerobe** that thrives in warm, brackish water and is known to cause severe wound infections and sepsis, particularly in individuals who consume raw seafood or have open wounds exposed to contaminated water. *Gram-negative aerobe* - While some Gram-negative bacteria are aerobes, a purely aerobic organism would not fit the typical growth characteristics of **Vibrio vulnificus**, which is **facultative anaerobic**. - No common obligate Gram-negative aerobes are primarily associated with the rapid, severe wound infection seen after oyster exposure. *Gram-positive clusters* - **Staphylococcus** species are Gram-positive bacteria that grow in clusters and can cause skin infections, but they are generally not associated with oyster exposure or the rapid progression described. - The mechanism of infection via oyster shucking points away from typical staphylococcal wound infections. *Gram-positive chains* - **Streptococcus** species are Gram-positive bacteria that grow in chains and can cause various infections, including cellulitis, but they are not typically linked to seafood-related wound infections like **Vibrio vulnificus**. - The clinical context strongly favors a different causative agent. *Gram-negative anaerobe* - While there are Gram-negative anaerobes, such as **Bacteroides**, they are primarily found in the gut flora and are less commonly implicated in acute wound infections acquired from environmental exposure like oysters. - **Vibrio vulnificus** is a **facultative anaerobe**, meaning it can grow with or without oxygen, which is distinct from obligate anaerobes.

Bacteria US Medical PG Question 2: A 42-year-old woman with a history of multiple sclerosis and recurrent urinary tract infections comes to the emergency department because of flank pain and fever. Her temperature is 38.8°C (101.8°F). Examination shows left-sided costovertebral angle tenderness. She is admitted to the hospital and started on intravenous vancomycin. Three days later, her symptoms have not improved. Urine culture shows growth of Enterococcus faecalis. Which of the following best describes the most likely mechanism of antibiotic resistance in this patient?

• A. Increased efflux across bacterial cell membranes
• B. Production of beta-lactamase
• C. Alteration of penicillin-binding proteins
• D. Alteration of peptidoglycan synthesis (Correct Answer)
• E. Alteration of ribosomal targets

Bacteria Explanation: ***Alteration of peptidoglycan synthesis*** - **Vancomycin** targets the **D-Ala-D-Ala terminus** on the peptidoglycan precursor, preventing cross-linking during bacterial cell wall synthesis. - **Vancomycin resistance in Enterococcus faecalis** occurs through acquisition of resistance genes (vanA, vanB) that encode enzymes modifying the peptidoglycan precursor from **D-Ala-D-Ala to D-Ala-D-Lac**. - This structural change reduces vancomycin's binding affinity by approximately 1000-fold, rendering the antibiotic ineffective. - The mechanism directly involves **alteration of the peptidoglycan synthesis pathway**, specifically the terminal amino acid residues of the pentapeptide precursor. *Increased efflux across bacterial cell membranes* - This mechanism involves **efflux pumps that actively transport antibiotics out of the bacterial cell**, reducing intracellular concentration. - While efflux pumps contribute to resistance for antibiotics like **tetracyclines, fluoroquinolones, and macrolides**, this is not the primary mechanism of vancomycin resistance in Enterococcus. *Production of beta-lactamase* - **Beta-lactamase enzymes** hydrolyze the **beta-lactam ring** of antibiotics like **penicillins and cephalosporins**, rendering them inactive. - **Vancomycin is a glycopeptide antibiotic, not a beta-lactam**, so its efficacy is not affected by beta-lactamase production. *Alteration of ribosomal targets* - This mechanism confers resistance to antibiotics that target **bacterial ribosomes** to inhibit protein synthesis, such as **macrolides, aminoglycosides, and tetracyclines**. - **Vancomycin acts on cell wall synthesis**, not protein synthesis, so alteration of ribosomal targets is not relevant to vancomycin resistance. *Alteration of penicillin-binding proteins* - **Penicillin-binding proteins (PBPs)** are the targets of **beta-lactam antibiotics** (penicillins, cephalosporins, carbapenems). - Alterations in PBPs cause resistance to beta-lactams, not to vancomycin. - **Vancomycin does not interact with PBPs**; it binds directly to the D-Ala-D-Ala terminus of peptidoglycan precursors in the cell wall.

Bacteria US Medical PG Question 3: An investigator is studying the chemical structure of antibiotics and its effect on bacterial growth. He has synthesized a simple beta-lactam antibiotic and has added a bulky side chain to the molecule that inhibits the access of bacterial enzymes to the beta-lactam ring. The synthesized drug will most likely be appropriate for the treatment of which of the following conditions?

• A. Folliculitis (Correct Answer)
• B. Nocardiosis
• C. Atypical pneumonia
• D. Erythema migrans
• E. Otitis media

Bacteria Explanation: ***Folliculitis*** - The bulky side chain provides **steric hindrance** that prevents **staphylococcal beta-lactamases** from accessing and degrading the **beta-lactam ring**. - This modification creates an **anti-staphylococcal penicillin** (similar to methicillin, nafcillin, or oxacillin), which is effective against **methicillin-sensitive *Staphylococcus aureus* (MSSA)**. - **Folliculitis** is most commonly caused by *S. aureus*, making this modified beta-lactam an appropriate treatment choice for MSSA-related folliculitis. - The bulky side chain specifically protects against the **penicillinase** (beta-lactamase) produced by staphylococci. *Otitis media* - Otitis media is commonly caused by beta-lactamase-producing organisms like *Haemophilus influenzae* and *Moraxella catarrhalis*. - However, the beta-lactamases produced by these gram-negative organisms are **not inhibited by bulky side chains** alone. - Treatment of beta-lactamase-producing *H. influenzae* and *M. catarrhalis* requires **beta-lactamase inhibitors** (such as clavulanic acid combined with amoxicillin), not steric hindrance. - The mechanism of protection differs: beta-lactamase inhibitors **suicide inhibitors** that bind to the enzyme, whereas bulky side chains provide **physical blocking**. *Nocardiosis* - Nocardiosis is caused by *Nocardia* species, which are **aerobic actinomycetes**. - These bacteria are typically treated with **sulfonamides** (trimethoprim-sulfamethoxazole) for prolonged periods. - Beta-lactam antibiotics are generally not first-line treatment, as *Nocardia* species often show intrinsic resistance or require specific antibiotic combinations. *Atypical pneumonia* - Atypical pneumonia is caused by organisms like *Mycoplasma pneumoniae*, *Chlamydophila pneumoniae*, and *Legionella pneumophila*. - These organisms lack a **peptidoglycan cell wall**, which is the target of all **beta-lactam antibiotics**. - Beta-lactams (regardless of modifications) are completely ineffective against atypical pneumonia pathogens. - Treatment requires **macrolides** (azithromycin), **tetracyclines** (doxycycline), or **fluoroquinolones**. *Erythema migrans* - Erythema migrans is the characteristic rash of early **Lyme disease**, caused by *Borrelia burgdorferi*. - While *Borrelia* is sensitive to certain beta-lactam antibiotics (amoxicillin, ceftriaxone), it does **not produce beta-lactamases**. - The bulky side chain modification is unnecessary for treating *Borreria* infections, as there is no beta-lactamase to protect against. - Standard treatment uses doxycycline, amoxicillin, or ceftriaxone—not anti-staphylococcal penicillins.

Bacteria US Medical PG Question 4: A 59-year-old man presents to the emergency room for a fever that has persisted for over 4 days. In addition, he has been experiencing weakness and malaise. His past medical history is significant for a bicuspid aortic valve that was replaced 2 years ago. Physical exam reveals nailbed splinter hemorrhages, tender nodules on his fingers, and retinal hemorrhages. An echocardiogram shows aortic valve vegetations and culture reveals a gram-positive alpha-hemolytic organism that grows as cocci in chains. The organism is then exposed to optochin and found to be resistant. Finally, they are seen to ferment sorbitol. The most likely cause of this patient's symptoms is associated with which of the following?

• A. Pneumonia
• B. Colon cancer
• C. IV drug use
• D. Dental procedures (Correct Answer)
• E. Sexual activity

Bacteria Explanation: ***Dental procedures*** - The patient's presentation with **infective endocarditis** (fever, weakness, malaise, splinter hemorrhages, Osler nodes [tender nodules], Roth spots [retinal hemorrhages], and valve vegetations) is caused by a gram-positive alpha-hemolytic, optochin-resistant, sorbitol-fermenting coccus in chains. - These microbiologic characteristics identify **viridans group streptococci** (such as *Streptococcus mutans* or *S. sanguinis*), which are **normal oral flora**. - The patient's **prosthetic aortic valve** makes him particularly susceptible to endocarditis, and **dental procedures** can introduce these oral bacteria into the bloodstream, leading to bacteremia and valve seeding. - This is why patients with prosthetic valves require **antibiotic prophylaxis** before dental procedures. *Pneumonia* - While pneumonia can cause fever and malaise, it doesn't lead to the characteristic peripheral stigmata of **endocarditis** like splinter hemorrhages, Osler nodes, or Roth spots, nor valve vegetations. - The organism isolated (alpha-hemolytic, optochin-resistant viridans streptococci) is normal oral flora, not a typical cause of pneumonia. *Colon cancer* - **Colon cancer** is strongly associated with endocarditis caused by ***Streptococcus gallolyticus* (formerly *S. bovis* biotype I)**. - However, the microbiologic description in this case (particularly optochin resistance and sorbitol fermentation) identifies **viridans streptococci**, not *S. gallolyticus*. - If this were *S. gallolyticus* endocarditis, colonoscopy would be indicated to screen for colorectal malignancy. *IV drug use* - **IV drug use** is a major risk factor for **right-sided endocarditis**, particularly involving the **tricuspid valve**, typically caused by ***Staphylococcus aureus***. - This patient has **left-sided** (aortic) **prosthetic valve endocarditis** caused by viridans streptococci, which is not the typical pattern for IV drug use. *Sexual activity* - **Sexual activity** is not a risk factor for **infective endocarditis** caused by viridans streptococci. - While certain sexually transmitted pathogens can rarely cause systemic complications, they do not predispose to endocarditis with oral flora organisms.

Bacteria US Medical PG Question 5: A 71-year-old woman presents with high-grade fever and chills, difficulty breathing, and a productive cough with rust-colored sputum. She complains of a sharp left-sided chest pain. Physical examination reveals increased fremitus, dullness to percussion, and bronchial breath sounds on the lower left side. A chest X-ray shows left lower lobe consolidation. The offending organism that was cultured from the sputum was catalase-negative and had a positive Quellung reaction. The organism will show which gram stain results?

• A. Gram-negative diplococci
• B. Cannot be seen with gram staining since the organism lacks a cell wall
• C. Gram-positive cocci in clusters
• D. Gram-negative rod
• E. Gram-positive diplococci (Correct Answer)

Bacteria Explanation: ***Gram-positive diplococci*** - The clinical presentation (high fever, chills, productive cough with **rust-colored sputum**, sharp chest pain, signs of **consolidation**) is classic for **pneumococcal pneumonia**. - The organism responsible for pneumococcal pneumonia, *Streptococcus pneumoniae*, is a **Gram-positive, catalase-negative diplococcus** that exhibits a **positive Quellung reaction** due to its polysaccharide capsule. *Gram-negative diplococci* - This describes organisms such as **Neisseria meningitidis** or **Neisseria gonorrhoeae**, which cause meningitis or gonorrhea, respectively, not typical pneumonia. - While *Moraxella catarrhalis* is a Gram-negative diplococcus that can cause respiratory infections, it typically causes otitis media or sinusitis and less commonly severe pneumonia with rust-colored sputum. *Cannot be seen with gram staining since the organism lacks a cell wall* - This description typically refers to **Mycoplasma pneumoniae**, which causes **atypical pneumonia** and lacks a cell wall, rendering it unstainable by Gram stain. - Mycoplasma pneumonia usually presents with a more indolent course, a non-productive cough, and rarely causes rust-colored sputum or lobar consolidation seen on X-ray. *Gram-positive cocci in clusters* - This morphology is characteristic of **staphylococci**, such as *Staphylococcus aureus*, which can cause pneumonia, often in immunocompromised individuals or as a complication of influenza. - However, *Staphylococcus aureus* is **catalase-positive**, and its pneumonia presentation can be more fulminant, often leading to abscess formation, differing from the typical presentation of pneumococcal pneumonia. *Gram-negative rod* - This morphology is characteristic of various bacteria including **Klebsiella pneumoniae**, **Pseudomonas aeruginosa**, or **Haemophilus influenzae**. - **Klebsiella pneumoniae** can cause severe pneumonia with **currant jelly sputum** but is a Gram-negative rod and would not exhibit a Quellung reaction in the same manner as *S. pneumoniae*.

Bacteria US Medical PG Question 6: A 35-year-old female presents to the emergency room complaining of diarrhea and dehydration. She has been experiencing severe watery diarrhea for the past 3 days. She reports that she has been unable to leave the bathroom for more than a few minutes at a time. The diarrhea is profuse and watery without visible blood or mucus. She recently returned from a volunteer trip to Yemen where she worked at an orphanage. Her past medical history is notable for psoriasis for which she takes sulfasalazine. The patient drinks socially and does not smoke. Her temperature is 99°F (37.2°C), blood pressure is 100/55 mmHg, pulse is 130/min, and respirations are 20/min. Mucous membranes are dry. Her eyes appear sunken. Capillary refill is 4 seconds. The patient is started on intravenous fluid resuscitation. Which of the following processes is capable of transmitting the genetic material for the toxin responsible for this patient's condition?

• A. Transposition
• B. Conjugation
• C. Endospore formation
• D. Transduction (Correct Answer)
• E. Transformation

Bacteria Explanation: ***Transduction*** - The patient's symptoms are highly suggestive of **cholera**, caused by *Vibrio cholerae*, which produces **cholera toxin**. - The genes for cholera toxin are carried on a **bacteriophage (CTXφ)**, and their transfer between bacteria occurs via **transduction**. *Transposition* - **Transposition** involves the movement of **transposons ("jumping genes")** within a genome or between DNA molecules. - While transposons can carry antimicrobial resistance genes or virulence factors, this mechanism is not typically associated with the transfer of the primary cholera toxin genes. *Conjugation* - **Conjugation** is the transfer of genetic material between bacteria through direct cell-to-cell contact, often involving a **pilus** and the transfer of **plasmids**. - While *Vibrio cholerae* can engage in conjugation, the cholera toxin genes are predominantly acquired via specialized transduction with the CTXφ phage, not typically plasmid-mediated conjugation. *Endospore formation* - **Endospore formation** is a survival mechanism used by certain bacteria (e.g., *Clostridium*, *Bacillus*) to withstand harsh environmental conditions. - It is not a mechanism for **horizontal gene transfer** or the transmission of toxin-encoding genetic material between bacteria. *Transformation* - **Transformation** is the uptake of **naked DNA** from the environment by a bacterial cell. - While *Vibrio cholerae* can be naturally competent for transformation, the cholera toxin genes are primarily acquired through **phage-mediated transduction**, not free DNA uptake.

Bacteria US Medical PG Question 7: A 62-year-old man is brought to the emergency department from a senior-care facility after he was found with a decreased level of consciousness and fever. His personal history is relevant for colorectal cancer that was managed with surgical excision of the tumor. Upon admission, he is found to have a blood pressure of 130/80 mm Hg, a pulse of 102/min, a respiratory rate of 20/min, and a body temperature 38.8°C (101.8°F). There is no rash on physical examination; he is found to have neck rigidity, confusion, and photophobia. There are no focal neurological deficits. A head CT is normal without mass or hydrocephalus. A lumbar puncture was performed and cerebrospinal fluid (CSF) is sent to analysis while ceftriaxone and vancomycin are started. Which of the following additional antimicrobials should be added in the management of this patient?

• A. Trimethoprim-sulfamethoxazole (TMP-SMX)
• B. Ampicillin (Correct Answer)
• C. Amphotericin
• D. Meropenem
• E. Clindamycin

Bacteria Explanation: ***Ampicillin*** - This patient is a 62-year-old, indicating an increased risk for **Listeria monocytogenes** meningitis, which is typically susceptible to ampicillin. - Given his age and presentation with **meningeal signs** and fever, empirical coverage for Listeria with ampicillin is crucial, especially before CSF culture results are known. *Trimethoprim-sulfamethoxazole (TMP-SMX)* - While TMP-SMX can cover Listeria, it is generally considered a **second-line agent** for severe infections like meningitis due to slower bactericidal activity and potential for higher rates of treatment failure compared to ampicillin. - Ampicillin is the **preferred first-line treatment** for Listeria meningitis unless there is a specific contraindication. *Amphotericin* - Amphotericin is an **antifungal agent** used for fungal meningitis. - Although fungemia can occur in immunocompromised individuals or those with indwelling catheters, the initial presentation with bacterial meningitis symptoms and absence of specific risk factors for fungal infection do not support its empirical use. *Meropenem* - Meropenem is a **carbapenem** with a broad spectrum of activity, including many gram-negative and gram-positive bacteria, and some anaerobes. - While it has good CNS penetration and could cover some organisms like penicillin-resistant S. pneumoniae or gram-negative rods, it is not the primary empirical choice specifically for **Listeria monocytogenes**, and there's no indication for its broad-spectrum coverage over standard empirical therapy currently. *Clindamycin* - Clindamycin is primarily active against **gram-positive bacteria**, especially anaerobes and some staphylococci and streptococci. - It has **poor penetration into the CNS** and is therefore not effective for meningitis treatment, especially for common bacterial pathogens or Listeria.

Bacteria US Medical PG Question 8: A 27-year-old man presents to the emergency department with weakness and a fever for the past week. The patient is homeless and has a past medical history of alcohol and IV drug abuse. His temperature is 102°F (38.9°C), blood pressure is 107/68 mmHg, pulse is 120/min, respirations are 17/min, and oxygen saturation is 98% on room air. Physical exam is notable for a tremulous patient with antecubital scars and a murmur over the left lower sternal border. Blood cultures are drawn and the patient is started on vancomycin and ceftriaxone and is admitted to the ICU. The patient's fever and symptoms do not improve despite antibiotic therapy for which the initial identified organism is susceptible. Cultures currently reveal MRSA as one of the infective organisms. Which of the following is the best next step in management?

• A. Transesophageal echocardiography (Correct Answer)
• B. Obtain new blood cultures
• C. CT scan of the chest
• D. Nafcillin and piperacillin-tazobactam
• E. Vancomycin and gentamicin

Bacteria Explanation: ***Transesophageal echocardiography*** - The patient's history of **IV drug abuse**, **fever**, **new murmur**, and identification of **MRSA** strongly suggest **infective endocarditis**. - A Transesophageal echocardiography (TEE) is the **most sensitive and specific imaging modality** to detect vegetations, abscesses, or valvular damage, which is crucial for guiding further management. *Obtain new blood cultures* - While repeating blood cultures can be useful to confirm eradication or identify new pathogens, the initial blood cultures already revealed MRSA, which is a common cause of **endocarditis in IV drug users**. - The immediate priority given the lack of improvement and high suspicion of endocarditis is to visualize the heart valves for vegetations. *CT scan of the chest* - A CT scan of the chest would be useful to look for complications such as **septic emboli in the lungs** or other pulmonary pathologies. - However, it would not provide the detailed visualization of heart valves necessary to diagnose or rule out valvular vegetations characteristic of endocarditis. *Nafcillin and piperacillin-tazobactam* - **Nafcillin** is active against **methicillin-susceptible Staphylococcus aureus (MSSA)**, but the patient's cultures already identified **MRSA**. - **Piperacillin-tazobactam** is a broad-spectrum antibiotic but not a first-line treatment for MRSA infections and would not be appropriate given the identified pathogen. *Vancomycin and gentamicin* - The patient is already on **Vancomycin**, which is appropriate for MRSA, but adding **gentamicin** without clear indication would not be the best next step. - While gentamicin is sometimes used as an adjunct in specific endocarditis regimens (e.g., enterococcal), the primary concern here is the lack of clinical improvement despite appropriate MRSA coverage, pointing towards a structural cardiac issue.

Bacteria US Medical PG Question 9: A group of microbiological investigators is studying bacterial DNA replication in E. coli colonies. While the cells are actively proliferating, the investigators stop the bacterial cell cycle during S phase and isolate an enzyme involved in DNA replication. An assay of the enzyme's exonuclease activity determines that it is active on both intact and demethylated thymine nucleotides. Which of the following enzymes have the investigators most likely isolated?

• A. DNA ligase
• B. Telomerase
• C. Primase
• D. DNA topoisomerase
• E. DNA polymerase I (Correct Answer)

Bacteria Explanation: ***DNA polymerase I*** - **DNA polymerase I** possesses **5' to 3' exonuclease activity**, which is crucial for removing **RNA primers** (intact nucleotides) laid down by primase during DNA replication. - This 5' to 3' exonuclease activity also allows it to excise damaged DNA, including DNA containing **demethylated thymine nucleotides**. - It also has 3' to 5' exonuclease activity for proofreading. - **Key distinction:** While DNA polymerase III (the main replicative enzyme) only has 3' to 5' exonuclease activity, DNA polymerase I has **both** 3' to 5' and 5' to 3' exonuclease activities, making it essential for primer removal and DNA repair. *DNA ligase* - **DNA ligase** functions to form a **phosphodiester bond** between adjacent nucleotides to seal nicks in the DNA backbone, but it does not have exonuclease activity. - Its primary role is in joining Okazaki fragments and repairing single-strand breaks. *Telomerase* - **Telomerase** is a specialized reverse transcriptase that extends the telomeres at the ends of eukaryotic chromosomes, but is not present in prokaryotes like *E. coli*. - It uses an RNA template to synthesize DNA, and it lacks exonuclease activity. *Primase* - **Primase** is an RNA polymerase that synthesizes short **RNA primers** on the DNA template, providing a starting point for DNA synthesis. - It is involved in synthesizing primers, not in removing or excising nucleotides, and has no exonuclease activity. *DNA topoisomerase* - **DNA topoisomerases** relieve supercoiling in DNA during replication and transcription by cutting and rejoining DNA strands. - While they act on DNA, their function is to manage topological stress, and they do not exhibit exonuclease activity on nucleotides.

Bacteria US Medical PG Question 10: 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)

Bacteria 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.

Bacteria Flashcard 1 of 10

Question: _____ lack the enzymes Superoxide Dismutase and Catalase

Answer: Obligate Anaerobes (Obligate Aerobes or Anaerobes)

Bacteria Flashcard 2 of 10

Question: _____ can generate lots of energy through cellular respiration using O2

Answer: Obligate Aerobes (Obligate Aerobes or Anaerobes)

Bacteria Flashcard 3 of 10

Question: Vancomycin-intermediate staphylococcus aureus (VISA) has an unusually thickened _____

Answer: cell wall

Bacteria Flashcard 4 of 10

Question: Bunches/Clusters of cocci bacteria are known as _____

Answer: Staphylococci

Bacteria Flashcard 5 of 10

Question: _____ of High Frequency bacterial strains allows us to perform genetic mapping

Answer: Conjugation

Bacteria Flashcard 6 of 10

Question: Beta-lactamases are synthesized by _____ genes

Answer: plasmid

Bacteria Flashcard 7 of 10

Question: Yersinia enterocolitica is _____, protecting the bacteria from phagocytosis

Answer: encapsulated

Bacteria Flashcard 8 of 10

Question: Staphylococcus saprophyticus infections spread via _____

Answer: bodily fluids

Bacteria Flashcard 9 of 10

Question: Rocky Mountain spotted fever

Answer: Ricketsia rickettsii

Extra Information: headache; fever; rash beginning in wrists and ankles, progresses to trunk, palms, and solesdoxycycline

Bacteria Flashcard 10 of 10

Question: epidemic typhus

Answer: Rickettsia prowazeckii

Extra Information: rash that begins centrally and spreads but spares palms and solesdoxycycline