Practicum B Exam Micro Flashcards
Enterobacteriaceae members can be indigenous microflora and can be….
Opportunistic pathogens
Salmonella and shigella are not indigenous microflora and are always…
pathogenic
Enterobacteriaceae are associated with what kind of human diseases….
Abscesses
GI Tract infections
Meningitis
Pneumonia
Septicemia
UTIs
Wound infections
Enterobacteriaceae are the most common causes of ….
nosocomial infections
Extra intestinal infections by enterobacteriaceae family can be…
UTIs, respiratory infections, wound infections, bloodstream infections, and CNS infections
What enterbacteriaceae cause the most GI tract infections?
- Escherichia
- Salmonella
- Shigella
- Yersinia
List phenotypic characteristics of enterobacteriaceae
- Gram negative bacilli or cococcobacilli
- Facultative anaerobes
- Nonspore forming
- Glucose fermenters
- Catalase positive - except shigella dysenteriae
- Oxidase negative except plesiomonas shigelloides
- Reduce nitrate to nitrite
- Growth on MacConkey agar
- Most motile by peritrchous flagella
What are the non motile members of enterobacteriaceae?
Klebsiella and shigella
List lactose fermenter of enterobacteriaceae
E. coli
Klebsiella
Pantoea
Enterobacter
Citrobacter
Serratia
List non lactose fermenter of enterobacteriaceae
Salmonella
shigella
Proteus
Morganella morganii
Providencia
Yersinia
List nonmotile and non H2S producers of enterobacteriaceae that are nonlactose fermenter
Shigella and yersinia
List motile and H2S producer of enterobacteriaceae that are non lactose fermenter
Proteus and Salmonella
What are the antigens of enterobacteriaceae?
O - Outer membrane
H - Flagella
K - Capsule
Vi - Capsule of Salmonella
List organisms of enterobacteriaceae that would produce (TSI Test) A / A with gas no H2S.
Escherichia, klebsiella, and enterobacter
List organisms of enterobacteriacea that would produce (TSI test) K / A, no gas, and no H2S
Shigella and Serratia
List organisms of enterbacteriaceae that would produce (TSI test) K / A, with gas and H2S.
Salmonella and Proteus
What organism from enterobacteriaceae would produce (TSI test) K / K, no gas and no H2S?
Pseudomonas
What sugars are in KIA medium?
1 part glucose and 10 part lactose
What kind of decarboxylase enzymes are tested in the decarboxylase test?
Lysine, ornithine, and arginine
What indicators are used in the decarboxylase test?
bromocresol purple and cresol red that can result in color change from orange to purple or red.
The decarboxylase test is not only useful for the enterobacteriaceae family but for differentiating which two members of the enterobacteriaceae?
Salmonella ( +vVE) and shigella (=VE)
What is produced by decarboxylation of amino acids?
Urea. If there is decarboxylation of amino acids the urease test will be positive (pink color). The process alkalinizes the medium leading to a pink color
What is the principle of the indole test?
To determine if the organism possesses tryptophanase that will deaminate tryptophan into indole, pyruvic acid, ammonia, and energy. A positive result will be a red color. A negative result will be no red color.
What is the reagent of the indole test?
Kovac’s reagent.
The MR of IMViC test uses what reagent and what does a positive test look like?
MR reagent; A positive test is a red color. A negative result is a yellow color.
What reagents are used in the VP test of IMViC?
KOH and naphthol. A positive result will be a red color. A negative result will be a yellow color.
What does the citrate determine about the bacteria?
Determines if the organism has the ability to use sodium citrate as its sole carbon source and inorganic ammonium salts as its only nitrogen source.
A positive result will be a color change from green to blue. A negative result will be no growth and a green medium color.
What is the IMViC for E. coli?
+ / + / = / =
What is the IMViC for E. aerogenes?
= / = / + / +
What is the IMViC for E. cloacae?
= / = / + / +
What is the IMViC for K. pneumoniae?
= / = / + / +
What is the MUG test?
Fluorogenic assay to detect the presence of the enzyme beta glucuronidase. A disk containing 4-methylumbelliferyl-𝝱-D-glucuronide (MUG) is dampened with water, the organism is applied, and the disk is incubated at 35℃ for up to 2 hours.
A positive result will fluoresce meaning the presence of 4-methyllumbelliferyl.
What is the biochemical rxn of E. coli?
Gram negative
Catalase positive
Oxidase negative
Nitrate reduction positive
Indole Positive
MR positive
VP negative
Citrate negative
The virulence factor Lipid + polysaccharide gives E. coli an advantage how?
Makes phagocytosis difficult for WBCs
Lipid A virulence factor of E. coli givens an advantage how?
Its an endotoxin component that causes fever and shock
What is the K - antigen for E. coli?
Capsule
What is the O - antigen for E. coli?
Component of LPS in outer membrane
What is the H - antigen for E. coli?
Flagella
E. coli virulence factor adhesins is advantageous b/c…?
It allows the bacteria to bind to cell lining of bladder
E coli virulence factor hemolysin or HlyA is advantageous b/c?
It lyses erythrocytes
What antigen is present in neonatal meningitis (mother too) when E. coli is causing it?
K 1 capsular antigen
Enteropathogenic E. coli (EPEC) is associated with what disease?
Classic infant diarrhea
Enterotoxigenic E. coli (ETEC) is associated with what disease?
Traveler’s diarrhea
Enteroaggregative E. coli (EAEC) is associated with what disease?
Watery diarrhea, mainly in infants
Enterohemorrhagic E. coli (EHEC) is associated with what disease?
Hemorrhagic colitis (large intestine)
Enterinvasive E. coli (EIEC) is associated with what disease?
Dysentery (verocytotoxins present)
What kind of plate can be used to isolate O157 shiga toxin producing E. coli STEC strains?
SMAC plates also known as sorbitol containing MAC
Describe Klebsiella biochemical rxn + gram stain characteristic
Gram Negative, encapsulated, and non-motile.
Lactose fermenters
Indole Negative
MR Negative
VP Positive
Citrate positive
Oxidase negative
Nitrate positive
Klebsiella colonizes which part of the human body?
Nasopharynx and GI tract
Klebsiella are associated with what kind of infection?
Nosocomial infections such as…
UTI
Blood stream
Lower respiratory tract
Cardiovascular infection
Wound infection
Ear infection
Nose infection
Throat infection
K. oxytoca can be isolated where in the human body?
Blood, urine, respiratory tract, and stool
What two bacterias cause chronic granulomatous disease of upper respiratory tract in tropical areas?
K. rhinoslceromatis -> rhinoscleroma
K. ozaenae -> rhinitis
What kind of antibiotic resistance is common in K. pneumoniae strains?
ESBL also known as extended - spectrum beta - lactamases
What antibiotic is E. coli and klebsiella resistant to?
CRE also known as carbapenem resistant. The antibiotic is part of a class of Beta - lactam antibiotics which inhibit cell wall syntehsis
What biochemical tests differentiates K. pneumoniae and K. oxytoca?
Indole test. Pneumoniae is indole negative. Oxytoca is indole positive
What biochemical test could differentiate K. ozaenae and K. rhinoscleromatis from each other?
ONPG test. Ozaenae is variable but K. rhinoscleromatis is ONPG negative.
Both are indole, Orn. decarboxylase, and VP negative.
What biochemical test could differentiate K. pneumoniae and K. ozaenae?
VP also known as Voges - Proskauer test. K. pneumoniae is positive while K. ozaenae is negative.
Both are Indole and Ornith. decarboxylase negative. K. pneumoniae is ONPG positive while K. ozaenae is variable.
What is the purpose of the ONPG test?
Detect late lactose fermentor usually requiring more than 24 hours of incubation to be lactose positive. The test utilizes a chemical similar to lactose (ONPG) to detect the enzyme beta - galactosidase. The enzyme will convert the lactose similar structure into galactose and o-nitrophenol both being yellow colored.
A positive test will be a yellow color.
