Chapter 1 - Bacteriology Flashcards
Fermentation end-products are often used to aid the identification of bacteria. Fermentation results in:
Conversion of glucose to pyruvate
The exchange of cellular DNA between two living bacterial cells that involves an intercellular bridge is called
Conjugation
End-products of aerobic respiration
Carbon dioxide and water
This mechanism involves cell-to-cell contact, a series of complex chemical signals between cells, and usually the formation of a BRIDGE or SEX PILUS
Conjugation
This mechanism involves the uptake of free DNA by a recipient cell
Transformation
This mechanism involves the acquisition of DNA through the action of a BACTERIOPHAGE.
> mediated by VIRUSES, by which DNA from two bacteria may come together in one cell, RECOMBINATION
Transduction
A mordant that is applied after the primary stain to chemically bond the alkaline dye to bacterial cell wall
Gram’s iodine
Bacteria considered as important pathogens when reading gram-stained smears of SOFT TISSUE ABSCESS
Staphylococcus aureus
3% to 5% CO2
Aerobes
5% O2, 10% CO2, 85% N
Microaerophilic
85% N2, 10% H2, 5% CO2
Anaerobic
This medium is very selective for enteric pathogens and is differential for Salmonella and Shigella
Hektoen Enteric Agar
HEA: Yellow-orange colonies
Lactose fermenters (E. Coli)
HEA: colorless/green colonies with unchanged medium
Non-lactose fermenter (Shigella, Providencia)
If w/ Black colonies: h2s production (Salmonella)
Coagulase bound to the surface of the cell
Clumping factor
The slide coagulase test is a rapid screening tesr for the production of
Free coagulase
The Staphylococcus sp. that is more likely to cause uncomplicated urinary tract infections in nonhospitalized hosts, especially sexually active young women
Staphylococcus saprophyticus
Toxic Shocks syndrome toxin-1 is an important virulence factor in staphylococcal disease. This toxin is classified into which group of toxins
Enterotoxin
Mannitol Salt Agar is selective and differential for which organism
Staphylococcus
The toxins of this organism are preformed in contaminated food
> the organism doesnt need to grow in the host and therefore the action is very rapid
Staphylococcus aureus
Susceptible to bile and optochin, a-hemolytic, and major cause of bacterial meningitis, often carrying an antiphagocytic capsule
Streptococcus pneumoniae
Susceptible to penicillin and bacitracin, B-hemolytic, PYR positive, major cause of bacterial pharyngitis, and often carrying an antiphagocytic M protein
Streptococcus pyogenes
Hippurate hydrolysis-positive, B-hemolytic, a major cause of neonatal meningitis and sepsis, producer of CAMP factor
Streptococcus agalactiae
Appearance of a Green band of RBCs around a colony (conversion of hemoglobin to methemoglobin)
Alpha hemolysis
A pathogenic, gram-positive bacilli that grows well at Refrigerator temperature
Listeria monocytogenes
This organism grows on tellurite medium, grows as black colonies with brown halos in Tinsdale medium, and shows gram-positive bacilli in irregular clublike shapes
Corynebacterium diphteriae
Clinical disease that shows gray pseudomembrane covering the oropharynx
Diptheria
Gram-positive bacillus, catalase-negative, H2S producer, nonmotile, nonsporeformer that can be found in a skin lesion
Erysipelothrix spp.
CAMP test positive, H2S negative and esculin negative
Listeria spp.
CAMP test negative, H2S positive, Esculin positive
Erysipelothrix spp
This is used in decontaminating sputum samples for the successful isolation of Mycobacterium tuberculosis
N-acetyl-L-cysteine (NALC)- NaOH mixture
This Mycoplasma organism is AFB positive but potentially noncultivable
Mycoplasma leprae
Mycoplasma tuberculosis complex consists of these 4 organisms:
1) M. tuberculosis
2) M. Bovis (in cattle)
3) M. bovis BCG (vaccine strain for the BCG vaccine)
4) M. africanum (in Western Africa and clinically similar to M. tuberculosis)
Runyon group that is slow growing, and produce a yellow-orange pigment when exposed to light
Runyon 1- Photocromogens
Runyon group that is slow growing, and produces a yellow-orange pigment in LIGHT or in DARK
Runyon 2- Scotochromogens
Runyon group that is slow growing, and do not produce pigment. Although some may produce very pale yellow, buff or tan pigment but do not intensify upon light exposure
Runyon 3- Nonchromogenic
Runyon group consisting of rapid growers
Runyon 4
The Tween 80 test involves Lipase that is able to hydrolyze _____ _____ _____ into ____ _____ and ______ _____
Polysorbate 80 ➡️ Oleic Acid + polyoxyethylated sorbitol
Ph Indicator of Tween 80 test
Phenol red
They are resistant to heat, cold, drying, most chemicals and boiling
Spores
The gram negative bacillus that can be described as oxidase-negative, nitrate-positive, indole-negative, citrate -positive, methyl red-positive, urease-negative, and H2S-positive
Salmonella enteritidis
The swarming gram-negative bacillus that can be described as oxidase-negative, nitrate-positive,indole-negative, and H2S-positive (SIM: + - +)
Proteus mirabilis
Profuse water diarrhea “rice water stools”, leading to dramatic fluid loss, severe dehydration, and hypotension that frequently leads to death, is the hallmark of what toxin?
Cholera toxin
The selective medium thiosulfate citrate bile salts sucrose (TCBS) agar is especially formulated for isolating which pathogen from stool cultures?
Vibrio spp.
The majority of human infections with Campylobacter spp. are caused by?
Contamination of food, milk or water with animal feces
In the test for urease production, the presence of the enzyme hydrolyzes urea to ___ and ____
ammonia + CO2
A cytotoxin that causes inflammation and ulcerative lesions, destroys epithelial cells, and results in bloody, mucous-laden stools
Shiga Toxin
One of the most common causes of food-borne, human bacterial gastroenteritis in the US.
Campylobacter jejuni
This organism grows well on XLD agar and is a nonfermenting organism that produces H2S, resulting in black pigment
Salmonella enteritidis
This organims appears as clear colonies on XLD agar
Shigella sonnei
Both of these organisms are lactose fermenting and appear as yellow colonies on XLD agar
Serratia and Klebsiella
Decarboxylation of the amino acids lysi\ne, ornithine, and arginine results in the formation of what end-products
amines
Identify the organism: TSI reaction: K/A H2s - negative Gas - not produced
Shigella spp.
The best specimen for the isolation of bordetella pertussis
Nasopharyngeal swabs
Gram-stain morphology of Brucella spp.
Gram - negative coccobacilli
this organism is seen on patients with pneumonia and this requires specialized medium for growth, 35*C, CO2, and extended incubation, hold for 2 weeks
Legionella pneumophila
Whic medium provides the NAD necessary for the growth of Haemophilus spp.
Chocolate agar (has X and V factors required for growth of Haemophilus spp.)
Growth around the only the X and V factor disks on the agar surface in FactorRequirement Test supports the identification of what species
Haemophilus
One of the HACEK group of bacteria known to cause subacute bacterial endocarditis. It is asaccharolytic, oxidase- positive bacilli that do not grow on MacConkey Agar and produces a BLEACH-LIKE odor. It is often assoc. with wounds of the mouth or teeth
Eikenella corrodens
The bacterial species that can be described as oxidase-positive, glucose-positive, maltose-positive, sucrose-negative, lactose-negative, and a major cause of bacterial meningitis
Neisseria meningitidis
The bacterial species that can be described as oxidase-positive, glucose-positive, maltose-negative, sucrose-negative, lactose-negative, and a major cause of venereal disease
Neisseria gonorrhea
Gram stained appearance of the genus Neisseria
Gram-negative diplococci
The Hugh-Leifson oxidative fermentative (OF) test shows a pH shift in the open glucose tube and no pH in the closed tube. this indicates this organism is an:
Oxidizer or Nonoxidizer?
Oxidizer
This is a critical test when attempting to identify nonfermenting gram-negative bacilli
Oxidase Test
The oxidase test is designed to determine the presence of this enzyme. This enzyme is also a part of the energy transfer cascade of intermediate metabolism.
Cytochrome oxidase
The blood culture of a patient with a central venous catheter yielded a gram- negative bacillus (NLF) growing on MacConkey agar, green-lavender or yellow pigment on chocolate agar and blood agar, oxidase (-), catalase (+), and esculin (+). This organism strongly oxidizes maltose but only weakly oxidizes glucose
Stenotrophomonas maltophila
This organism is associated with Meliodosis
Burkholderia pseudomallei
Differentiation of Stenotrophomonas maltophila and Burkholderia cepacia is best accomplished by which test?
Oxidase test
Stenotrophomonas: Oxidase (-)
Burkholderia: Oxidase (+)
The respiratory culture of a patient with cystic fibrosis yielded a gram-negative bacillus, Oxidase (+), Soluble green pigment on TSA slant, Motility (+)
Pseudomonas aeruginosa
Which test group best differentiates Acinetobacter baumannii from Pseudomonas aeruginosa
Oxidase, Motility, Nitrate reduction
Pseudomonas: Oxidase (+), Motile
Acinetobacter: Oxidase (-), Nonmotiel
Cystic tryptic Agar (CTA) sugar reactions are used to differentiate Neisseria spp. If Moraxella catarrhalis is tested in this system, the isolate will be
Glucose, Maltose, Lactose, and Sucrose NEGATIVE
A soluble, bright green pigment produced by Pseudomonas aeruginosa is known as
Pyocyanin
A small portion of a colony of a gram-negative bacilli was smeared onto a filter paper test system. One percent tetramethyl-p-phenylenediamine dihydrochloride was added. At 10 secs, a dark purple color developed. What does this test result exhibit?
Positive oxidase Test
Characteristics of both Mycoplasma and Ureaplasma genera
They only have a cell membrane with no cell wall
What organism causes Nongonococcal Urethritis (NGU)
Ureaplasma urealyticum
This is the most sensitive method for the diagnosis of Chlamydia trachomatis
Nucleic Acid amplification
This is the most common rickettsial disease in US and characterized by abrupt onset of fever headache and muscle aches, rash beginning on hands and feet spreading toward the trunk. Diagnosis includes fluorescent antibody or PCR
Rocky Mountain spotted fever
Which stage of venereal syphilis is characterized by the appearance of a chancre that typically heals within 6 weeks?
Primary syphilis
It is nontreponemal serologic test in which soluble antigen particles are coalesced to form larger particles that are visible as clumps when they are aggregated by antibody?
Venereal Disease Research Laboratory (VDRL) test
Lyme disease with signs of partial facial paralysis and painful joints is caused by which infectious agent
Borrelia burgdorferi
A lesion in the groin area, lack of demonstable organism in the lesion by gramstained smear, and reactive in RPR test can be diagnosed as syphilis caused by?
Treponema pallidum
Under anaerobic incubation conditions, it grew as smooth, white nonhemolytic colonies. This organism was not inhibited by colistin, kanamycin, or vancomycin, and hydrolyzed esculin.
Bacteroides fragilis
Pseudomembranous colitis caused by Clostridium difficile is best confirmed by what laboratory finding?
Presence of the toxin in stool
Lecithinase production, double zone hemolysis on SBA and gram-stained morphology are all useful criteria in the identification of?
Clostridium perfringens
The most common way to confirm that an anaerobic system has the correct gas mixture
Change in color of the methylene blue indicator.
In a clinical specimen from neck, mouth or resp tract, the presence of sulfur granules strongly indicates the presence of which anaerobic bacterium?
Actinomyces spp.
These are a common element between using the E test and agar disk diffusion (Kirby-Bauer) for antimicrobial susceptibility testing
Both establish an antibiotic gradient in agar
What clinical condition would most benefit from having quantitative (MIC) testing rather than quantitative (Sensitive, Intermediate, Resistant categories) data from the laboratory?
Bacterial meningitis (from CNS)
The lowest concentration of an antibiotic in dilution series that inhibits growth
Minimium Inhibition Concentration
The higher the MIC of the drug for that organism; The _____ is the zone of inhibition
The larger is the zone of inhibition
Infection and/or inflammation of the terminal portion of the lower urinary tract
Urethritis
Strptococcus pneumoniae commonly associated with Otitis Media is positive with
Optochin
Organism most often responsible for Impetigo
Streptococcus pyogenes
How do staphylococci spread so easily when infecting the skin?
They produce Hyaluronidase, which hydrolyzes hyaluronic acid in the intracellular ground substance that makes up connective tissue
Routine culture media for use with a specimen of CSF should include whic sets of media?
5% SBA, Chocolate Agar Thioglycolate broth
Clinical symptoms include fever, intense headache, stiff neck, sensitivity to light and low WBCs. This is diagnosed as meningitis. What tests hould be ordered next?
CSF Gram Stain and culture
What cells are found in bacterial vaginosis?
Clue cells
Which term is used to describe an increase of lymphocytes and other mononuclear cells (pleocytosis) in the CSF and negative bacterial and fungal cultures?
Aseptic meningitis
The culture of which sample routinely uses quantitation or the counting of bacterial cells present to assist in the interpretation? This is done to aid the differentiation of true infection from contamination
Urine
These practices are done to ensure that the test results are accurate.
Quality Control
The overall process of ensuring the quality of the results reported by the laboratory and includes quality control, employee training, and certification.
Quality Assurance
Substances known or reasonably expected to contain pathogens
Infectious substances
An example of inappropriate specimen or condition that would warrant rejection for microbiology culture
A 24-hr urine sample for bacteriology culture
