GENERALITIES Flashcards
Mechanism of Resistance in some Antibiotics

• Reducing microbial contamination to an acceptable “safe” level (terminology used in food safety)
Sanitization
• Heating cutlery
(e.g. at KFC!)
the only bacteria WITH sterols.
mycoplasma
• Rapid cell division occurs
• b-Lactam antibiotics act during this phase
• Constant growth rate
• Continues until either one or more nutrients in the medium become exhausted, or toxic metabolites accumulate and inhibit growth.
PHASE 2: LOG OR EXPONENTIAL PHASE

Protein A is found in
S. aureus
Appearance of the vacuolated neurons, as well as their loss of function and the lack of an immune response or inflammation
SPONGIFORM ENCEPHALOPATHIES
- Most of the cells die because nutrients have been exhausted
- Negative growth rate
PHASE 4: DECLINE OR DEATH PHASE

o induces the overproduction of cytokines, such as TNF & IL-1
o activates the complement cascade
o activates the coagulation cascade, resulting in disseminated intravascular coagulation
Lipid A
Which of the following is the OLDEST acid-fast staining method, which requires heating the specimen during the procedure?
Ziehl-Neelsen
- Noncellular infectious proteins
- Naked proteins that have the same amino acid sequence as certain normal human cell surface proteins but have folded differently
- These are misfolded proteins with the ability to transmit their misfolded shape onto normal variants of the same protein. They characterize several fatal and transmissible neurodegenerative diseases in humans and many other animals
- Pathology: dysfunction due to protein misfolding
PRIONS
• Physical removal of microorganisms by using such things as soaps or detergents
Degerming or Cleaning
- Handwashing with soap and running water
Destroys or eliminating ALL forms of microbial life, including spores
Sterilization
- Steam sterilization (autoclaving)
- Note that prions require anadapted form ofsterilization because of their high resistanceto any form of sterilization.
Xylose-McCullough-Johnson-Harris (EMJH) / Fletcher’s Medium
Leptospira Interrogans
A–B subunit of Exotoxins
o A subunit is the active (toxic) subunit
o B subunit is the binding subunit
completely dependent on oxygen for ATP-generation
Obligate Aerobes
- • Nocardia, Bacillus cereus, Neisseria, Pseudomonas, Bordetella, Legionella, Brucella, Mycobacterium, Leptospira, Mycoplasma pneumoniae
mediate attachment of bacteria
pili
What are the non-essential components of bacteria?

DNA is transfered from one bacterium to another
Conjugation
Spore: formed by gram-positive rods, especially ______
Bacillus and Clostridium spp
Prokaryotic ribosomes
50S + 30S = 70S
Bordet-Gengou Agar
Bordetella pertussis
Eukaryotic Ribososmes
60S + 40S = 80S
Purified DNA is taken up by a cell
Transformation
BACTERIA WITH IGA PROTEASE
SHiNe My Gong
Streptococcus pneumoniae
Haemophilus influenzae
Neisseria Meningitidis
Neisseria Gonorrhoeae
What are the essential components of bacteria

utilize oxygen if it is present, but can use fermentation in its absence
Facultative Anaerobes
• Staphylococcus, Bacillus anthracis, Corynebacterium, Listeria, Mycoplasmas (in general)
Barbour-Stoenner-Kelly (BSK)
Borrelia burgdorferi
All bacterial capsules are composed of polysaccharide EXCEPT
Bacillus anthracis (polypeptide of D-glutamate)
Lowenstein Jensen Agar
M. Tuberculosis
Tellurite Agar
Corynebacterium diphtheriae
M Protein is found in
S. pyogenes
Bile Esculin Media
group D streptococci
Bacterial reproduction occurs via
binary fission
Which group of infectious agents does not require DNA as genetic material?
Prions
allows adherence to mucous membranes
immunoglobulin A (IgA) protease
What king of sterols do these organisms have?
Protozoa and animals – ______
Fungi – _______
Protozoa and animals – cholesterol
Fungi – ergosterol
Which component of the susceptibility to lysozymes?
Outer membrane
CHOCOLATE AGAR + FACTORS X and V
Haemophilus influenzae
mediates strong adherence to surface of human cells
glycocalyx
Endotoxin Shock is caused by presence of __
Lipid A
Thiosulfate Citrate Bile Salts (TCBS) Agar
Vibrio cholera
exclusively anaerobic but insensitive to the presence of oxygen
Aerotolerant Anaerobes
• Propionibacterium (Cutibacterium), Lactobacillus
All bacteria have a cell wall composed of peptidoglycan except ____
Mycoplasma – Mycoplasma do not have cells walls!
All exotoxins are HEAT-LABILE EXCEPT
Staphylococcal Enterotoxin
Gram Staining Steps

Colon normal flora
Bacteroides, Escherichia coli
Exotoxin vs Endotoxin

Dental plaque normal flora
Streptococcus mutans
surface proteins called _____ mediate binding to endothelium and to extracellular proteins such as fibronectin
curli
Eaton
Mycoplasma pneumoniae
accelerates formation of a fibrin clot coating the organisms with a layer of fibrin
coagulase
BLOOD-BRAIN BARRIER PENETRABILITY

Unique to Gram (-) organisms
Endotoxin/lipopolysaccharide
Periplasmic space
Outer membrane
autoclave must reach and maintain a temperature of ______ for around ______ by using saturated steam under at least _____ of pressure.
121° C
15-20 minutes
15 psi
Vagina normal flora
- Lactobacillus vaginalis
- Escherichia coli
- Streptococcus agalactia
Lipopolysaccharide on the outer membrane of gram-negative bacteria consists of ___
Lipid A and O antigen → induction of IL-1 & TNF
spread through subcutaneous tissue
collagenase and hyaluronidase
use fermentation but can tolerate low amounts of oxygen because they have SOD
Microaerophiles
• Streptococcus, spirochetes (Borreliella, Treponema), Campylobacter, Helicobacter
Examples of Bacterial Toxins

Bacteria not seen in Gram Stain

Eliminates many or all pathogenic microorganisms, except bacterial spores, on inanimate objects
Disinfection
- • Application ofrubbing alcohol – to inanimate objects
Unique to Gram (+) organisms
Teichoic Acid
Charcoal-yeast extract
Legionella pneumophila
- Exhaustion of nutrients or the accumulation of toxic products cause growth to cease completely (zero growth rate)
- Spores are formed
PHASE 3: STATIONARY PHASE

PROPHAGE-CODED BACTERIA
Lysogenized strains of ABCDE
- shigA – like toxin: EHEC
- Botulinum
- Cholera
- Diphtheria
- Erythrogenic toxin
*genetic mechanism responsible for the conversion of a nontoxigenic strain to a toxigenic strain is Lysogenic phage conversion
toxic component of LPS
Lipid A
Bacterial Growth Cycle
- Cells are depleted of metabolites as the result of unfavorable condition
- Adaptation to new environment
- Nutrients are incorporated
- Vigorous metabolic activity occurs but cells do not divide
- Zero growth rate
PHASE 1: LAG PHASE

Chocolate Agar
N. meningitidis and N. gonorrhea from STERILE SITES
All gram-positive bacteria have NO endotoxin EXCEPT
Listeria monocytogenes
destroys both neutrophilic leukocytes and macrophages (e.g. Panton-Valentine leucocidin or PVL)
leucocidin
Antibiotics that have activity against P. aeruginosa include:
- Aminoglycosides (Gentamicin, Amikacin, Tobramycin, but not Kanamycin)
- Quinolones (Ciprofloxacin, Levofloxacin, but not Moxifloxacin)
- Cephalosporins (Ceftazidime, Cefepime, Cefoperazone,Cefpirome, Ceftobiprole, but not Cefuroxime, Cefotaxime, or Ceftriaxone)
- Antipseudomonal Penicillins: Carboxypenicillins (Carbenicillin and Ticarcillin), and Ureidopenicillins (Mezlocillin, Azlocillin, and Piperacillin). P. aeruginosa is intrinsically resistant to all other Penicillins.
- Carbapenems (Meropenem, Imipenem, Doripenem, but not Ertapenem)
- Polymyxins (Polymyxin B and Colistin)
- Monobactams (Aztreonam)
cannot grow in the presence of oxygen because they lack SOD, peroxidase and catalase
Obligate Anaerobes
• Actinomyces, Bacteroides, Clostridium
Skirrows Medium
Campylobacter, helicobacter
DNA is transferred by a VIRUS from one cell to another
Transduction
Egg Yolk agar
Clostridium perfringens
- microorganisms that are the permanent residents of the body
- low-virulence organisms in their usual anatomic site
- colonization resistance occurs when normal flora occupy receptor sites preventing pathogens from binding
NORMAL FLORA
Cetrimide Culture medium
Pseudomonas aeruginosa
Mannitol Salts
Staphylococci
Mouth normal flora
viridans Streptococci
Thayer Martin Agar
N. gonorrhea from NONSTERILE sites
- a.k.a. “transposable” elements
- Mobile genetic elements
- DNA pieces that move readily from one site to another either within or between the DNA of bacteria, plasmids, and bacteriophages
- “Jumping genes”
- “Cut and paste” or “copy and paste”
- Code for drug-resistant enzymes, toxins, or metabolic enzymes
- Cause mutations in genes into which they insert (via a mutation) or alter the expression of nearby genes (e.g. causing the activation or repression of antibiotic resistance genes).
TRANSPOSONS
- Patient related: Disinfection or living tissue or skin
- Healthcare worker related: Reduction or removal of transient microbial flora
Antisepsis
- Preoperative skin prep
- Hand rubbing
Lysozymes are enzymes that kill bacteria by cleaving which part of the cell wall?
β 1→ 4 glycosidic bond between NAG and NAM
a.k.a. Neufeld reaction, a biochemical reaction in which antibodies bind to the bacterial capsule
Quellung reaction
ACID FAST staining steps
- Primary Stain - CArbol Fuchsin
- Mordant - Steam Heating
- DEcolorizing Agent - Acid
- Counterstain - Malachite Green / Blue