Mlab 2534 Microbiology Midterm

Salmonella is one of the enterics because it belongs to the Enterobacteriaceae family, which is a group of gram-negative bacteria that commonly inhabit the human gastrointestinal tract. Enterics are known for their ability to ferment glucose and produce acid and gas. Salmonella is a well-known enteric pathogen that can cause foodborne illnesses such as salmonellosis. Staph Aureus, Strep Pneumo, and N. meningitidis are not enterics as they do not belong to the Enterobacteriaceae family and do not possess the characteristic features of enteric bacteria.

Proteus is a genus of bacteria that is known to be urea positive. This means that it has the ability to break down urea, a waste product of protein metabolism, into ammonia and carbon dioxide. This characteristic is used as a diagnostic tool in identifying Proteus species in the laboratory. Therefore, the given statement is true.

Strep pneumo (Streptococcus pneumoniae) appears as gram positive lancet shaped dipplococci on a gram stain. This means that when stained using the Gram staining technique, the bacteria will retain the purple color and appear as pairs of oval-shaped cells with pointed ends. This characteristic morphology helps in the identification of Strep pneumo in the laboratory. Gram positive rods, gram negative rods, and gull wings are not the typical appearances of Strep pneumo on a gram stain.

Blood Agar plates are primarily used for the detection of hemolysis. Hemolysis refers to the breakdown of red blood cells, and it is often used as an indicator for certain bacteria. Different types of hemolysis can be observed on Blood Agar plates, including alpha-hemolysis (partial breakdown resulting in a greenish discoloration), beta-hemolysis (complete breakdown resulting in a clear zone around the bacterial colonies), and gamma-hemolysis (no breakdown). By observing the type of hemolysis, it can help in the identification and differentiation of bacteria. Therefore, the correct answer is C. Hemolysis.

Staphylococcus saprophyticus is the most common cause of cystitis in healthy sexually active women after Escherichia coli. This bacterium is a common inhabitant of the genital tract and can cause urinary tract infections when it enters the urethra and travels up into the bladder. It is more frequently isolated from women than men, and it is often associated with sexual activity. Staphylococcus saprophyticus is resistant to many antibiotics commonly used to treat urinary tract infections, making it important to accurately identify and treat infections caused by this bacterium.

Staph Aureus appears on a gram stain as gram positive grape-like clusters. This means that when stained using the Gram staining technique, Staph Aureus bacteria retain the violet crystal stain and appear purple under a microscope. The bacteria are arranged in clusters that resemble grapes. This characteristic staining pattern helps in the identification and classification of Staph Aureus bacteria.

Salmonella is a type of bacteria commonly found in undercooked poultry and can cause food poisoning. When poultry is not cooked thoroughly, the bacteria may survive and cause illness when consumed. Symptoms of Salmonella poisoning include diarrhea, vomiting, abdominal pain, and fever. It is important to cook poultry to the appropriate internal temperature to kill any bacteria present and prevent foodborne illnesses.

An H2S producing Salmonella would most likely appear as a black colony because the production of hydrogen sulfide (H2S) by Salmonella leads to the formation of black precipitates. This black coloration is due to the reaction between H2S and iron compounds in the growth medium. Therefore, a black colony would indicate the presence of Salmonella that produces H2S.

Streptococcus pyogenes is the correct answer because it is a common bacterial pathogen known to cause sore throat, specifically strep throat. This bacterium is highly contagious and can be transmitted through respiratory droplets. It is responsible for a range of infections, including pharyngitis, tonsillitis, and scarlet fever. Staphylococcus aureus can also cause sore throat, but it is less common compared to Streptococcus pyogenes. Haemophilus spp and Mycoplasma pneumoniae are not typically associated with bacterial sore throat.

A bacteriocide is a substance that completely kills bacteria. Disinfectants are substances that kill or inhibit the growth of microorganisms, including bacteria, but they may not completely eliminate all bacteria. Bacterostatic substances inhibit the growth and reproduction of bacteria, but do not necessarily kill them. Alcohol can kill some bacteria, but it may not be effective against all types of bacteria. Therefore, the correct answer to the question is C. Bacteriocide.

The correct answer is B. Staph Aureus. The CAMP test is a microbiological test used to identify bacteria that produce a protein called CAMP factor. Staphylococcus aureus is one of the bacteria that produces this factor, so it is streaked down the center of the test plate to check for the characteristic arrowhead-shaped hemolysis that indicates a positive result. Strep A, E. Coli, and S. Sapro are not typically involved in the CAMP test.

E. Coli is the leading cause of UTIs in females. This is because E. Coli is a type of bacteria that is commonly found in the gastrointestinal tract and can easily travel from the anus to the urethra in females, leading to infection in the urinary tract.

The correct answer is D. S. Sapro. S. Sapro stands for Staphylococcus saprophyticus, which is a type of bacteria that commonly causes urinary tract infections (UTIs) in females. While E. coli is the most common cause of UTIs in females, S. sapro is the second leading cause. K. Pnuemo and Acintobactor are not commonly associated with causing UTIs.

Autoclave sterilization is a process used to kill microorganisms and sterilize lab media. The correct parameters for autoclave sterilization include a pressure of 15 lbs, a temperature of 121°C, and a time of 15 minutes. This combination of pressure, temperature, and time ensures that the lab media is effectively sterilized and free from any potential contaminants.

The IMViC test is a series of tests used to differentiate between members of the Enterobacteriaceae family. The results of the test are indicated by the symbols ++--, which represent the presence or absence of certain metabolic activities. In this case, the ++-- pattern is characteristic of E. Coli, indicating that it is the correct answer. PsA, Staph Aureus, and Citrobactor do not exhibit this specific pattern of results in the IMViC test.

A candle jar is a method for incubating anaerobes because it creates an anaerobic environment by burning a candle inside a sealed jar. As the candle burns, it consumes the oxygen inside the jar, creating a low-oxygen or oxygen-free environment suitable for the growth of anaerobic organisms. This method is commonly used in laboratories to culture anaerobic bacteria, as they cannot survive in the presence of oxygen.

If a K. Pneumo is found to be an ESBL, it means that it is producing extended-spectrum beta-lactamase enzymes, which can break down and inactivate certain antibiotics. Cephalosporins, aztreonam, and penicillins are all beta-lactam antibiotics, which means that they contain a beta-lactam ring structure that is susceptible to degradation by ESBL enzymes. Therefore, if a K. Pneumo is ESBL-positive, it would automatically be reported as resistant to these antibiotics.

Bordet-Gengou Agar is a selective medium that is specifically designed to isolate Bordetella pertussis, the causative agent of whooping cough. This agar contains potato infusion, glycerol, and agar, which provide the necessary nutrients for the growth of Bordetella pertussis. Additionally, it also contains blood, which provides essential factors for the growth of the bacteria. The selective agents, such as crystal violet and cephalexin, inhibit the growth of other organisms, allowing for the isolation of Bordetella pertussis. Therefore, Bordet-Gengou Agar is the appropriate medium for the isolation of Bordetella pertussis.

Vancomycin is the treatment of choice for MRSA (methicillin-resistant Staphylococcus aureus) because it is one of the few antibiotics that is effective against this resistant strain of bacteria. MRSA is resistant to penicillin and other beta-lactam antibiotics, so penicillin (option D) is not an appropriate choice. Gentamycin (option A) and tobramycin (option B) are aminoglycoside antibiotics that are not typically used as the first-line treatment for MRSA. Therefore, the correct answer is C. Vancomycin.

A positive tube Coagulase test for a gram positive cocci would be considered confirmed positive because the test specifically detects the presence of the enzyme coagulase, which is produced by certain bacteria such as Staphylococcus aureus. A positive result indicates the presence of this specific enzyme and confirms the identification of the gram positive cocci as Staphylococcus aureus.

The primary cause for concern for Strep B in a pregnant woman is that it can cause meningitis in the baby. Strep B is a type of bacteria that can be present in the vagina or rectum of a pregnant woman. During childbirth, the baby can come into contact with the bacteria, which can lead to infection. If the bacteria enters the baby's bloodstream, it can cause meningitis, which is a serious infection of the membranes surrounding the brain and spinal cord. Meningitis can result in long-term complications or even death in newborns, making it a significant concern for pregnant women.

Klebsiella and Shigella are both motility negative organisms. Motility refers to the ability of an organism to move or exhibit self-propulsion. In the case of Klebsiella and Shigella, they lack the ability to move on their own. This is an important characteristic to note when identifying and differentiating between different types of bacteria. Salmonella and Proteus, Enterobactor and Citrobactor, and Proteus and Serratia are not both motility negative, so they are not the correct answer.

Campylobactor is a type of bacteria that appears as spiral rods on a gram stain. The term "gull wings" is used to describe the shape of these spiral rods, resembling the wings of a seagull. Therefore, option B is the correct answer as it accurately describes the appearance of campylobactor on a gram stain.

Rheumatic Fever is caused by the streptolysin O (SLO) produced by Streptococcus pyogenes bacteria. SLO is a potent toxin that causes damage to red blood cells, white blood cells, and platelets. It also contributes to the development of inflammation and tissue damage in the body, leading to the characteristic symptoms of Rheumatic Fever. Streptolysin A (SLA) is another toxin produced by Streptococcus pyogenes, but it is not directly associated with the development of Rheumatic Fever.

Corynebacterium Diptheriae appears as palisades on a gram stain. Palisades are a characteristic arrangement of bacteria where the cells align in a parallel manner, resembling a row of fence posts. This arrangement is commonly seen in Corynebacterium Diptheriae, which is a gram-positive bacterium that causes the respiratory disease diphtheria. The palisades arrangement helps in the identification of this bacterium on a gram stain.

Obligate anaerobes are microorganisms that cannot survive in the presence of oxygen. Oxygen is toxic to them and can cause damage to their cellular structures and metabolic processes. Therefore, they are harmed by oxygen and require an oxygen-free environment to grow and survive.

Campylobacter is an example of a capnophile, which is an organism that thrives in environments with high levels of carbon dioxide. This bacterium is commonly found in the intestines of animals and can cause foodborne illnesses in humans. It is adapted to survive and grow in low-oxygen environments, such as the gastrointestinal tract, where carbon dioxide levels are higher. Campylobacter infections are typically caused by consuming contaminated food or water, and symptoms can include diarrhea, abdominal pain, and fever.

Thioglycollate is mainly used as a back-up in case an anaerobe is present. This is because thioglycollate broth is a reducing medium that creates an environment suitable for the growth of anaerobic bacteria. It contains sodium thioglycollate, which acts as a reducing agent to remove oxygen from the medium. This allows the growth of anaerobic bacteria that cannot tolerate oxygen. Therefore, thioglycollate is commonly used in microbiology laboratories to support the growth of anaerobes and to determine their presence in a sample.

IMViC is a mnemonic that stands for Indole, Methyl Red, Voges-Proskauer, and Citrate. These are a series of biochemical tests used to identify and differentiate between different species of bacteria. Indole test determines the ability of bacteria to produce indole from the amino acid tryptophan, Methyl Red test detects the ability of bacteria to perform mixed acid fermentation, Voges-Proskauer test identifies bacteria that can produce acetoin, and Citrate test determines whether bacteria can utilize citrate as a carbon source. Therefore, option A is the correct answer as it includes all the correct components of the IMViC test.

After gram staining a gram positive cocci, the next test to be done would be the Catalase test. This test is used to differentiate between catalase-positive and catalase-negative organisms. Catalase-positive organisms produce the enzyme catalase, which breaks down hydrogen peroxide into water and oxygen. This can be observed by adding hydrogen peroxide to the bacteria, and if bubbles are produced, it indicates a positive result for catalase.

Enriched media refers to a type of culture medium that contains additional nutrients to support the growth of fastidious organisms. Chocolate agar is an example of enriched media as it contains blood, specifically red blood cells, which provides essential nutrients for the growth of certain bacteria. This type of media is commonly used in the laboratory to cultivate bacteria that require specific growth factors or nutrients not found in basic culture media.

ESBL stands for Extended Spectrum Beta Lactamase. This term refers to a group of enzymes produced by bacteria that can break down and inactivate certain antibiotics, specifically beta-lactam antibiotics. These enzymes are able to hydrolyze a wider range of beta-lactam antibiotics, including penicillins and cephalosporins, making them less effective in treating infections caused by bacteria that produce ESBLs. It is important to be aware of ESBL-producing bacteria in order to choose the appropriate antibiotics for treatment and prevent the spread of these resistant bacteria.

Campylobacter is a bacteria that causes foodborne illness in humans. It is commonly found in undercooked poultry and unpasteurized milk. The preferred temperature for Campylobacter to grow and multiply is 42 degrees Celsius. At this temperature, the bacteria can thrive and reproduce rapidly, increasing the risk of contamination and infection if proper food handling and cooking practices are not followed.

Psychrophiles are microorganisms that thrive in extremely cold temperatures. They are adapted to survive and reproduce in environments with temperatures as low as 15 degrees Celsius. This is because their cellular processes and enzymes are specifically designed to function optimally at these low temperatures. Therefore, psychrophiles prefer and are most active at temperatures around 15 degrees Celsius.

The question is asking about the method used to test for inducible clindamycin resistance. The correct answer is D, which suggests that there is a specific test, referred to as the "D Test," that is used for this purpose. The explanation does not provide any further details about the D Test or how it is conducted, but it confirms that it is the correct answer to the question.

After gram staining the gram negative rod and identifying it as Pseudomonas Aeruginosa, the next test to be done would be the Oxidase test. This test is used to determine the presence of the enzyme cytochrome c oxidase, which is found in the electron transport chain of aerobic bacteria. Pseudomonas Aeruginosa is known to be oxidase positive, so performing the oxidase test would help confirm the identification of the bacteria. The other tests mentioned (Catalase, Coagulase, and Indole) are not specific for identifying Pseudomonas Aeruginosa.

Optichin is an antibiotic that is used to test for the susceptibility of Streptococcus pneumoniae, also known as Strep Pneumo, to the drug. Therefore, the correct organism to use an optichin disk with is Strep Pneumo.

The correct answer is B. Grows slow. A fastidious organism refers to an organism that has specific and strict nutritional requirements for growth. These organisms often grow slowly because they require specific conditions and nutrients to thrive.

Necrotizing fasciitis is caused by the bacteria Streptococcus pyogenes, also known as Group A Streptococcus (Strep A). This bacteria can invade the deep layers of the skin and soft tissues, causing severe infection and tissue death. Strep A is commonly found on the skin and throat, and can enter the body through cuts, burns, or surgical wounds. It releases toxins that destroy the surrounding tissue and can rapidly spread, leading to a life-threatening condition if not treated promptly.

Group D organisms, specifically Enterococcus faecalis and Enterococcus faecium, have been associated with colon cancer. These bacteria have been found to promote inflammation and contribute to the development of colorectal tumors. Additionally, they have been shown to produce certain enzymes that can damage DNA and increase the risk of cancer. Therefore, Group D organisms are considered to be a potential risk factor for colon cancer.

A Mueller Hinton Plate is mainly used for susceptibility testing of bacteria. It is a standardized medium that provides consistent and reproducible results. The plate contains a specific concentration of nutrients and inhibitors to support the growth of bacteria and inhibit the growth of unwanted organisms. Susceptibility testing is performed to determine the effectiveness of antibiotics against specific bacteria, helping in the selection of appropriate treatment options for bacterial infections.

Shigella appears green on a HE (Hektoen Enteric) plate. HE agar is a selective and differential medium used to isolate and identify enteric pathogens, such as Shigella. The green color is due to the fermentation of lactose by Shigella, resulting in the production of acid. This acid production causes a pH change in the agar, leading to the appearance of green colonies. Other organisms may appear blue, pink, or white on the HE plate, but Shigella specifically appears green.

E. Coli 0517:H7 carries Shiga toxin. Shiga toxin is a toxin produced by certain strains of E. Coli bacteria, including the 0517:H7 strain. This toxin is responsible for causing severe symptoms such as bloody diarrhea and kidney damage in individuals infected with this strain of E. Coli.

Pseudomonas is the correct answer because it is indole-negative and oxidase-positive. Indole is a compound produced by some bacteria as a byproduct of tryptophan metabolism, and a negative result indicates that the bacteria does not produce indole. Oxidase is an enzyme that helps bacteria break down certain compounds, and a positive result indicates that the bacteria produces this enzyme. Staphylococcus, Streptococcus, and Neisseria do not fit these characteristics, making Pseudomonas the only correct option.

Strep Sapro is the organism that is resistant to Novabiacin.

McFarland's is a standard measure of bacterial concentration used in microbiology. A 0.5 McFarland's solution is equivalent to 1.5 x 10^8 colony-forming units (CFU) per milliliter. Therefore, it contains approximately 10^12 bacteria.

One of the primary media used to isolate anaerobes is KV Laked Blood. This medium is commonly used in microbiology laboratories for the cultivation and isolation of anaerobic bacteria. It contains blood, which provides essential nutrients for bacterial growth, and is supplemented with a reducing agent to create an anaerobic environment. This medium supports the growth of anaerobes and inhibits the growth of aerobic bacteria, allowing for the isolation and identification of anaerobic organisms.

A catalase negative grey pinpoint colony that is PYR positive is most likely Enterococcus. This is because Enterococcus is known to be catalase negative and can produce grey pinpoint colonies. Additionally, the PYR test is commonly used to differentiate between Enterococcus and other streptococci, as Enterococcus is PYR positive while most streptococci are PYR negative. Therefore, the combination of a catalase negative result, grey pinpoint colony morphology, and a positive PYR test strongly suggests Enterococcus.

Undercooked hamburger is commonly associated with E.Coli food poisoning. E.Coli, or Escherichia coli, is a type of bacteria that can be found in the intestines of animals, including cattle. When meat is not cooked thoroughly, the bacteria can survive and cause illness when consumed. Symptoms of E.Coli food poisoning may include diarrhea, abdominal pain, and vomiting. It is important to cook ground beef to a safe internal temperature to kill any potential bacteria and prevent food poisoning.

Beta lactamases act by locking up the beta lactam. This enzyme is produced by bacteria and is responsible for breaking down the beta lactam ring structure found in many antibiotics, rendering them ineffective. By locking up the beta lactam, the enzyme prevents the antibiotic from binding to its target site and exerting its antimicrobial activity. This allows the bacteria to survive and continue to cause infection.