Microbiology Toughest Exam: Quiz!

Gas gangrene (also known as "Clostridial myonecrosis"[1]:269, and "Myonecrosis"[2]) is a bacterial infection that produces gas tissues in gangrene. It is a deadly form of gangrene usually caused by Clostridium perfringens bacteria. It is a medical emergency.

Exfoliatin is a toxin produced by certain strains of bacteria, such as Staphylococcus aureus. This toxin causes scalded skin syndrome, a condition characterized by widespread redness, blistering, and peeling of the skin. Exfoliatin works by breaking down the proteins that hold skin cells together, leading to the detachment and shedding of the outer layers of the skin. This results in the characteristic symptoms of scalded skin syndrome.

Bacillus and Clostridium are both types of bacteria that belong to the gram-positive group. They are characterized by their rod-shaped (bacilli) structure and have the ability to form spores. This means that they can enter a dormant state, allowing them to survive in harsh conditions such as extreme temperatures or lack of nutrients. Therefore, the statement "Bacillus and Clostridium are gram-positive bacilli that form spores" is true.

Bacteroides are a type of bacteria commonly found in the oral cavity. They are known to be associated with periodontitis, which is an inflammatory disease that affects the gums and surrounding tissues. Bacteroides can contribute to the development and progression of periodontitis by producing harmful toxins and enzymes that damage the gums and bone supporting the teeth. Therefore, the statement that Bacteroides are associated with periodontitis is true.

All of the given statements are characteristics of Mycobacterium tuberculosis. The major virulence factors of this bacterium are cord factor and tuberuloproteins, which contribute to its ability to cause disease. The PPD skin test, which stands for purified protein derivative, is used to detect exposure to tuberculosis. It elicits a type IV delayed hypersensitivity reaction in individuals who have been previously exposed to the bacterium. Mycobacterium tuberculosis can cause both primary and secondary infections, depending on the individual's immune status and previous exposure to the bacterium.

The correct answer is "All of the above". This is because all three statements mentioned in the options are characteristics of Mycobacterium leprae. The tuberculoid type of leprosy is characterized by a cell-mediated immune response and the formation of granulomas in nerves. The lepromatous type of leprosy is characterized by the presence of foam cells containing bacteria in the skin. The major virulence factor of Mycobacterium leprae is lepromin. Therefore, all three statements are true and describe characteristics of Mycobacterium leprae.

Rickettsia rickettsii (abbreviated as R. rickettsii) is a unicellular, gram-negative coccobacillus (plural coccobacilli) that is native to the New World. It belongs to the spotted fever group (SFG) of Rickettsia and is most commonly known as the causative agent of Rocky Mountain spotted fever (RMSF). By nature, R. rickettsii is an obligate intracellular parasite that survive by an endosymbiotic relationship with other cells.
R. rickettsii is a non-motile, non-spore forming aerobic organism. Cells are typically 0.3-0.5 X 0.8-2.0 um in size. They lack a distinct nucleus and membrane bound organelles. Their outer membrane is composed mostly lipopolysaccharides.
RMSF is transmitted by the bite of an infected tick while feeding on warm-blooded animals, including humans. Humans are considered to be accidental hosts in the rickettsia–tick life cycle and are not required to maintain the rickettsiae in nature.

Streptolysin O, Streptolysin S, and Pneumolysin are all toxins produced by certain bacteria. These toxins cause the complete destruction of red blood cells, resulting in the release of hemoglobin and a clear zone around the bacterial colonies on blood agar plates. This type of hemolysis is known as beta-hemolysis.

The greatest risk of bloodborne infections among healthcare workers is HBV, which stands for Hepatitis B Virus. HBV is a highly contagious virus that is transmitted through contact with infected blood or bodily fluids. Healthcare workers are at an increased risk of exposure to HBV due to their close contact with patients and potential exposure to contaminated needles or other sharp objects. It is important for healthcare workers to follow strict infection control measures and get vaccinated against HBV to protect themselves and prevent the spread of the virus.

All Clostridium species are obligate anaerobic because they are unable to survive or grow in the presence of oxygen. These bacteria are adapted to environments with low oxygen levels and can only carry out their metabolic processes in the absence of oxygen. This characteristic is a defining feature of the Clostridium genus, making the statement true.

Staphylococcus aureus causes Scalded skin syndrome and Toxic Shock Syndrome. Scarlet Fever is caused by Streptococcus pyogenes, not Staphylococcus aureus. Rheumatic fever is also caused by Streptococcus pyogenes, not Staphylococcus aureus. Therefore, the correct answer is B and C.

Also is the most common STD
Forms cytoplasmic inclusions
Can be cotracted via swimming pool
Causes Trachoma and iinclusion conjuctivitis

Peptidoglycan is a cross-linked polysaccharide found in the cell walls of bacteria. It is composed of alternating N-acetylmuramic acid and N-acetylglucosamine residues. These two sugars are linked together by glycosidic bonds, forming a rigid structure that provides strength and protection to the bacterial cell wall. The cross-linking of peptidoglycan is essential for maintaining the integrity of the cell wall and preventing the bacteria from bursting due to osmotic pressure.

Streptococci species are known to be catalase-negative, meaning they do not produce the enzyme catalase. Additionally, they are gram-positive, which refers to their ability to retain the crystal violet dye during the Gram staining process. Therefore, the statement that all Streptococci species are catalase-negative and gram-positive is true.

Mycobacteria are known to be aerobic organisms, meaning they require oxygen to survive and grow. This is supported by their ability to utilize oxygen as a terminal electron acceptor in their metabolic processes. As such, they are able to thrive in environments with sufficient oxygen levels, such as in the lungs where they cause diseases like tuberculosis. Therefore, the statement "Mycobacteria are aerobic" is true.

Mycobacterium tuberculosis is a bacterium that causes tuberculosis, a highly contagious and potentially deadly disease. Disinfectant effectiveness is determined by its ability to kill or inactivate this bacterium. Since Mycobacterium tuberculosis is a particularly resilient and hardy bacterium, if a disinfectant is effective against it, it is likely to be effective against other less resistant bacteria as well. Therefore, the effectiveness of a disinfectant against Mycobacterium tuberculosis is a good indicator of its overall effectiveness as a disinfectant.

SIDE NOTE: Conjunctivitis is common in neonates (newborns), and silver nitrate or antibiotics are often applied to their eyes as a preventive measure against gonorrhoea.

NOTE: These plus Klebsiella, Pseudomonas, and Bacteroidies are classified as gram negative enteric bacteria. All of them are faculative with the exception of Pseudomonas and Baceroidies which are aerobic

They cant process O2 radicals and H2O2

It is the cause of "Fried Rice Syndrome". B. cereus bacteria are aerobes, and like other members of the genus Bacillus can produce protective endospores.

Pseudomonas aeruginosa is a common bacterial pathogen that often infects hospitalized patients, particularly those with burns or cystic fibrosis. This bacterium is known for its ability to colonize and infect damaged tissues, making it a frequent cause of infections in these patient populations. It is resistant to many antibiotics, making it difficult to treat, and can cause severe infections such as pneumonia, urinary tract infections, and bloodstream infections. Therefore, Pseudomonas aeruginosa is the most likely explanation for the given answer.

Conjugation - bacteria sex Transformation- uptake of random DNA, Transfection is a type of transformation. Transposon - transfer of DNA within the cell via moving DNA segments

Diphtheria (Greek διφθέρα (diphthera) "pair of leather scrolls") is an upper respiratory tract illness caused by Corynebacterium diphtheriae, a facultative anaerobic Gram-positive bacterium.[1][2] It is characterized by sore throat, low fever, and an adherent membrane (a pseudomembrane) on the tonsils, pharynx, and/or nasal cavityc

This lesion is often characterized as "wooden." "Sulfur" granules form in a central purulence surrounded by neutrophils. This conglomeration of organisms is virtually diagnostic of Actinomyces israelii.

Clostridium difficile is a bacterium that can cause antibiotic-associated pseudomembranous colitis. This condition occurs when the normal balance of bacteria in the colon is disrupted by antibiotic use, allowing Clostridium difficile to overgrow and release toxins that damage the lining of the colon. This can lead to symptoms such as severe diarrhea, abdominal pain, and fever. Clostridium tetani is the bacterium that causes tetanus, while Listeria monocytogenes is associated with foodborne illnesses. Therefore, the correct answer is Clostridium difficile.

Pseudomonas aeruginosa stains blue green in culture. This is because it produces a pigment called pyocyanin, which gives it a characteristic blue-green color. This staining pattern is useful in identifying the bacteria in laboratory settings.

Strep viridans is the correct answer because it is a type of bacteria that is commonly associated with dental caries, or tooth decay. It is often found in the oral cavity and can contribute to the formation of dental plaque, which leads to the demineralization of tooth enamel and the development of cavities. Strep pyogenes and Strep agalactae are not typically associated with dental caries, so they are not the correct answers.

Streptococcus pyogenes causes scarlet and rheumatic fever. Pyo, Red, Scarlet, Rheumatic
May also cause Toxic Shock Like Syndrome TSLS is people with preexisting infections.

Group A Beta Hemolytic Streptococci are distinguished by the presence of M protein on the outer surface of the cell. This protein is a major virulence factor and helps the bacteria evade the host immune response by inhibiting phagocytosis. The M protein also plays a role in the adherence of the bacteria to host cells and tissues. The presence of M protein is a characteristic feature of Group A Beta Hemolytic Streptococci and helps differentiate them from other types of streptococci.

Bacillus anthrasis is the correct answer because it is the only bacterium listed that has a D glutamate capsule. Clostridium perfringens and Clostridium difficle do not have this specific capsule.

Clostridium perfringens is the correct answer because it is known to produce Alpha toxin. Alpha toxin is a potent cytotoxin that can cause tissue damage and cell death. Clostridium perfringens is a common cause of food poisoning and gas gangrene, both of which are associated with the production of Alpha toxin. Bacillus anthrasis is the causative agent of anthrax and produces different toxins, while Clostridium difficile is associated with causing antibiotic-associated diarrhea but does not produce Alpha toxin.

IgA protease - degrades iga
Leukocidins - destroy PMNs
Protein A - inhibits complement

The major pathogens which can produce IgA proteases (extracellular enzymes capable of degrading IgA1) are Neisseria gonorrhoeae, N. meningitidis, Streptococcus pneumoniae, Haemophilus influenzae and bacteria associated with periodontal disease and dental plaque formation.

Rickettsia prowazekii is a species of gram negative, Alpha Proteobacteria, obligate intracellular parasitic, aerobic bacteria that is the etiologic agent of epidemic typhus, transmitted in the feces of lice. In North America, the main reservoir for R. prowazekii is the flying squirrel. R. prowazekii is often surrounded by a protein microcapsular layer and slime layer; the natural life cycle of the bacterium generally involves a vertebrate and an invertebrate host, usually an arthropod, typically the human body louse. A form of R.. prowazekii that exists in the feces of arthropods remains stably infective for months. R. prowazekii also appears to be the closest free-living relative of mitochondria, based on genome sequencing.

The correct answer is A and B. Both E. Coli and Staph Aureus are bacteria that are commonly associated with causing sepsis. E. Coli is a type of bacteria that is commonly found in the intestines and can cause infections if it enters the bloodstream. Staph Aureus is a type of bacteria that can cause various infections, including sepsis, if it enters the bloodstream. Strep Pyogenes and Clostridium Difficile are also bacteria that can cause infections, but they are not as commonly associated with sepsis as E. Coli and Staph Aureus.

Mycobacteria species have distinguishing features such as staining via acid fast staining and having mycolic acid in their cell wall instead of peptidoglycan. Acid fast staining is a special staining technique used to identify bacteria that have a waxy lipid layer in their cell wall, which makes them resistant to regular staining methods. Mycobacteria also have a unique cell wall composition with mycolic acid, a type of fatty acid, instead of peptidoglycan, which is found in the cell walls of most bacteria. These features help differentiate Mycobacteria from other bacterial species.

Diptheria - inhibits protein synthesis
Alpha toxin - lechinase (hydrolyzes lechin destroying plasma membrane)
Botulinum toxin - inhibit acetylcholine release

TSST stands for Toxic Shock Syndrome Toxin

Secondary TB has caseus granulomas

Stages of lyme disease:
Stage 1 - Erythema migrans
Stage 2 - Bells Palsy or neuropathies
Stage 3 - Arthritis and CNS disease

Stages of syphillis:
Primary - chancre at site of contact
Secondary - maculopapular rash and condyloma latum
Tertiary - Guma (granuloma) formation on tongue or palate

Brucella ap- Brucellosis (undulant fever)
Francsella tularenis - Tularemia vie rabbits
Yesternia pestis - Plague via fleas, rats and dogs
Pasturella multocida - Cellulitis

Haemophilus aegyptius, also known as Koch-Weeks bacillus, is the correct answer because it is a bacteria that causes acute conjunctivitis (pink eye). It is transmitted through hand to hand contact, making it highly contagious. Neisseria gonorrhoae is a bacteria that causes gonorrhea, not conjunctivitis. Haemophilus Influenzae is a bacteria that can cause various infections, but not specifically conjunctivitis. Listeria monocytogenes is a bacteria that causes foodborne illness, not conjunctivitis. Therefore, the correct answer is Haemophilus aegyptius.

Tetanus toxin inhibits glycine release. This means that it prevents the release of glycine, an inhibitory neurotransmitter in the central nervous system. By inhibiting glycine release, the toxin disrupts the balance between excitatory and inhibitory signals in the nervous system, leading to increased muscle stiffness and spasms characteristic of tetanus infection.

Rickettsia and Chlamydia are obligate intracellular bacteria because they are unable to replicate outside of a host cell. They rely on the host cell's machinery and nutrients to survive and reproduce. This characteristic allows them to evade the immune system and cause persistent infections. Spirochetes, such as Treponema pallidum, and Neisseria gonorrhoeae are not obligate intracellular bacteria as they can survive and replicate outside of host cells.

Cell wall not cell membrane

Beta Hemolytic Streptococci refers to a group of bacteria that are characterized by their ability to cause beta hemolysis, which is the complete lysis of red blood cells. Additionally, these bacteria have a specific carbohydrate composition in their cell wall known as C Carbohydrate. The Lancefield group is another name for Beta Hemolytic Streptococci, named after its discoverer, Rebecca Lancefield. Therefore, all of the given statements are true about Beta Hemolytic Streptococci.

Spirocettes have a flexible, thin cell wall
Mycoplasma lacks a cell wall

All are classified as Beta which means the undergo beta hemolysis.
Viridans and strep pneumaniae are classified as Alpha.

Mnemonic
SHESE

Possible mnemonic
STPH BEE