Medical Bacteriology: Pathogens and Infections

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A patient presents with severe cellulitis. Which of the following pathogens is the MOST likely cause of this infection?

Proteus mirabilis
Klebsiella pneumoniae
Aliivibrio vulnificus (correct)
Salmonella enterica

A hospital is experiencing an outbreak of pneumonia among its patients. Cultures reveal a Gram-negative bacterium resistant to multiple antibiotics. Which of the following organisms is MOST likely responsible for this outbreak?

Shigella spp.
Klebsiella pneumoniae (correct)
Helicobacter pylori
Yersinia pestis

A patient is diagnosed with a urinary tract infection (UTI). The causative agent is identified as a bacterium known to produce urease. Which of the following organisms is MOST likely responsible for this patient's infection?

Bdellovibrio spp.
Proteus mirabilis (correct)
Campylobacter jejuni
Borrelia burgdorferi

Several people who attended a poultry cookout develop severe intestinal enteritis. Which of the following bacteria is the MOST likely cause of this outbreak?

Campylobacter jejuni (A) Signup and view all the answers

A researcher is studying a bacterium capable of parasitizing other Gram-negative bacteria. This bacterium attaches to the outer membrane of its prey, eventually killing it. Which of the following organisms exhibits this predatory behavior?

Bdellovibrio spp. (B) Signup and view all the answers

A patient presents with symptoms of headache, fever, and rash after a recent tick bite. Which of the following organisms is the MOST likely causative agent?

R. rickettsii (C) Signup and view all the answers

A lab technician is tasked with culturing Neisseria spp.. Which of the following media would be MOST appropriate for this purpose?

Chocolate agar (A) Signup and view all the answers

Which of the following mechanisms is primarily responsible for the pathogenesis of Bordetella pertussis?

Paralysis of the movement of cilia (C) Signup and view all the answers

A hospital patient undergoing treatment for cystic fibrosis develops a severe respiratory infection. Cultures reveal the presence of a Gram-negative bacterium known for its antibiotic resistance. Which of the following organisms is the MOST likely culprit?

Buckholderia cepacia (C) Signup and view all the answers

A burn patient develops a severe wound infection characterized by bluish-green pus and a fruity odor. Which of the following organisms is the MOST likely cause?

Pseudomonas aeruginosa (A) Signup and view all the answers

A researcher isolates a bacterial strain capable of degrading xenobiotics. Which of the following organisms is MOST likely to exhibit this capability?

P.putida (C) Signup and view all the answers

Following a dog bite, a patient develops a localized skin infection with rapid onset. Which of the following organisms is the MOST likely causative agent?

Pasteurella multocida (A) Signup and view all the answers

A patient presents with severe diarrhea and dehydration after consuming contaminated seafood. The stool sample reveals a comma-shaped bacterium. Which of the following organisms is the MOST likely cause?

Vibrio parahaemolyticus (B) Signup and view all the answers

How does Staphylococcus epidermidis contribute to the health of human skin?

By producing antibacterials, creating an environment where other bacteria struggle to survive. (C) Signup and view all the answers

Lactobacillus spp. plays a crucial role in maintaining vaginal health. What is the primary mechanism through which it achieves this?

Producing lactic acid, which lowers the vaginal pH and inhibits the growth of pathogenic yeast and bacteria. (B) Signup and view all the answers

Which characteristic is shared by both Rickettsia spp. and Chlamydia trachomatis?

Both are intracellular parasites. (B) Signup and view all the answers

What distinguishes Rickettsia prowazekii from other species of Rickettsia?

It is transmitted by lice and causes epidemic typhus. (A) Signup and view all the answers

How does Bacteroides thetaiotaomicron benefit humans?

By breaking down complex polysaccharides that humans are unable to digest. (C) Signup and view all the answers

Which characteristic of Mycobacterium contributes most to its antibiotic resistance and slow growth?

The presence of mycolic acid in its cell wall. (B) Signup and view all the answers

Why is Escherichia coli considered both a mutualist and a parasite?

Because some strains produce vitamin K, while other strains cause diseases like hemolytic uremic syndrome. (B) Signup and view all the answers

A patient presents with difficulty breathing due to pseudomembranes in their throat. Which bacterium is the MOST likely cause?

Corynebacterium diphtheriae (B) Signup and view all the answers

What is the key characteristic of Rhizobium that makes it beneficial in agriculture?

Its ability to fix atmospheric nitrogen in the roots of legumes, increasing soil fertility. (D) Signup and view all the answers

A newborn develops pneumonia, sepsis, and meningitis shortly after birth. Which bacterium is the MOST likely causative agent?

Streptococcus agalactiae (C) Signup and view all the answers

How is Chlamydia trachomatis typically transmitted?

Through sexual contact or from mother to child during birth. (C) Signup and view all the answers

Which of the following is a key characteristic differentiating phototrophic bacteria?

Their differentiation based on proteo/nonproteo,sulfur/nonsulfur usage,and color pigments. (B) Signup and view all the answers

Which genus of bacteria is known for its role as a probiotic in yogurt and for competitively excluding harmful bacteria in the GI tract, vagina, and mouth?

Bifidobacterium (D) Signup and view all the answers

A patient who recently completed a course of strong antibiotics develops severe diarrhea. Which bacterium is MOST likely responsible?

Clostridium difficile (B) Signup and view all the answers

Which of the following bacterial species is MOST associated with dental caries (cavities)?

Streptococcus mutans (C) Signup and view all the answers

How does Clostridium tetani cause spastic paralysis?

By producing toxins that prevent the stopping of muscle contractions. (B) Signup and view all the answers

Which of the following characteristics is NOT associated with Staphylococcus epidermidis?

Production of enterotoxins. (B) Signup and view all the answers

Which scientist is credited with popularizing the idea that 'all cells come from other cells,' even though they weren't the originator?

Rudolf Virchow (D) Signup and view all the answers

What is the primary function of peptidoglycan in bacterial cell walls?

Protecting the cell from osmotic lysis and providing structural support. (C) Signup and view all the answers

Which of the following arrangements is NOT a recognized form for bacilli bacteria?

Staphylobacillus (A) Signup and view all the answers

In Gram staining, what is the purpose of using iodine?

To act as a mordant, forming a complex with crystal violet and trapping it in the cell wall. (B) Signup and view all the answers

How do non-photosynthetic bacteria obtain energy?

By utilizing energy from organic and inorganic chemical compounds. (B) Signup and view all the answers

What is the significance of the Rayleigh Criterion in microscopy?

It specifies the conditions under which two points of light are just resolvable as distinct entities. (C) Signup and view all the answers

Which of the following inclusions found in prokaryotic cells is associated with buoyancy?

Gas vacuoles (B) Signup and view all the answers

What role did Ignaz Semmelweis play in the history of microbiology and medicine?

He demonstrated that hand washing prevents disease transmission. (B) Signup and view all the answers

Which of the following describes secondary active transport in bacteria?

Relies on the electrochemical gradient established by another molecule's transport to move a different molecule against its concentration gradient. (C) Signup and view all the answers

Which of the following is NOT a unique characteristic of prokaryotic cells compared to eukaryotic cells?

70S ribosomes. (C) Signup and view all the answers

Which of the following scientists provided evidence supporting the endosymbiotic theory?

Lynn Margulis (A) Signup and view all the answers

Considering the electromagnetic spectrum, where does visible light fall in relation to infrared and ultraviolet radiation?

Visible light falls between infrared and ultraviolet radiation in terms of frequency. (B) Signup and view all the answers

What is the function of Nucleoid-Associated Proteins (NAPs) in prokaryotic cells?

To hold and compact DNA within the nucleoid region. (C) Signup and view all the answers

What is the correct way to write a species name using binomial nomenclature?

Genus species (D) Signup and view all the answers

Rhizobium

Nitrogen-fixing bacteria that live in legume roots.

Bacteroides thetaiotamicron

Mutualist in human gut that breaks down complex polysaccharides.