Bacteriology I

Front 1

Gram-positive bacteria

Back 1

Gram-positive organisms are able to retain crystal violet stain because of high amount of PEPTIDOGLYCAN (and teichoic acid) in cell wall.
Gram(+) cell walls typically lack outer membrane found in Gram-negative bacteria.

Front 2

What would you use for treating Rhodococcus equi pneumonia in horses?

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Macrolide drug Erythromycin is used in combination with rifampin

(Macrolides mainly effective against Gram+, mycoplasma)
BUT above all, know that MACROLIDES EFFECTIVE AGAINST CAMPY.

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Which macrolide is effective against mycoplasma?

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Tylosin

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For Avian chlamydiosis : Chlamydophila psittaci

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Tetracyclines effective

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Example of Fluoroquinolones?

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* ciprofloxacin
* enrofloxacin (Baytril): Broad spectrum (except for anaerobes)

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Enrofloxacin+silver sulfadiazine is used for?

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(‘Baytril Otic’ useful against canine OTITIS EXTERNA due to PSUEDOMONAS aeruginosa

Enrofloxacin is a fluoroquinolone, usually for UTI
Sulfadiazine is also usually for UTI

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Which TETRACYCLINES used primarly in cattle?


Which TETRACYCLINES used primarly in dogs?

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Oxytetracycline


Doxycycline (used in dogs)
> D for "dogs"

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Drug for pink eye in cattle ?

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Oxytetracyline LA (long acting) for pink eye in cattle (given as single IM injection)

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Name SULFONAMIDE + TRIMETHOPRIM drugs and animals used in:

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SulfadiaZine + trimethoprim for dogs
SulfadOXine + trimethoprim for large animals

~for UTI, upper resp., work by inhibiting DNA synth.

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what's good about enrofloxacin?

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enrofloxacin well distributed in dogs
(UTI, respiratory infections, pyoderma)

~ fluoroquinolones usually good for treating pseudomonas, gram-&+, mycoplasma, but not anaerobes

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Streptomycin is example of?

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AMINOGLYCOSIDES

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Best AMINOGLYCOSIDES?

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Gentamicin – for gram - incl. Pseudomonas aeruginosa

Amikacin & Tobramycin: better than gentamcin, incl. Pseudomonas, but only used in human infection.

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Beta-lactam Drugs (name 5)

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* PENICILLINS
* ampicillin
* amoxycillin
* ceftiofur (3rd gen.)??
* cefadroxil (1st gen.)

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3rd generation Cephalosporins

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Broad spectrum including Pseudomonas and some anaerobes. Longer duration, injected. e.g. Ceftazidime

note: interfer with cell wall synth. like all B-lactams

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Risk when using tetracyclines?

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- could destroy all normal flora in intestine; super infection with Candida (yeast) possible in all species when using tetrac. for long time

Front 16

What antibacterial drugs inhibit nucleic acid synthesis?

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* Fluoroquinolones (Enrofloxacin)
* Sulfonamides (SULFONAMIDE & TRIMETHOPRIM)

* Quinolones

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Polymyxins act how?

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damage to cell membrane function

- Effective against Gram- only
e.g. Polymyxin B – used topically or locally

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Nitroimidazoles used for?

Examples:

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Effective against anerobes
* Metronidazole
* Rifampin – used for Tb, combined with erythromycin for R. equi

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Example of Mycobacterium

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Mycobacterium tuberculosis

- waxy coating makes cells impervious to Gram staining so acid-fast used instead
- highly aerobic, so req. high levels of oxygen

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What is an example of an anaerobic bacteria?

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Clostridium perfringens

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Classify Clostridium:

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Gram-positive, rod-shaped, all anaerobic, spore-forming bacterium
(all Clostridium form spores)

Front 22

Name a bacteria with a capsule.

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Streptococcus pneumoniae:
Gram-positive, anaerobic

- more virulent than non-capsulated streptococcus

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Name a gram negative coccobacilli:

Where is this bacteria usually found?

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Pasteurella

* found in cat saliva or mouth. If cat get's wound, licking the cut will lead to infection with Pasteurella.

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Psychrophilic

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term for bacteria that grow at 4 degrees C, like Listeria and Yersinia enterocolitica

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Microaerophilic bacteria ?

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Some bacteria such as Campylobacter jejuni need reduced oxygen (5% instead of 20%).

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What is an example of an obligate anaerobe?

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Fusobacterium necrophorum

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What is a secondary pathogen?

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A pathogen that complicates the problem of the primary pathogen. Example Staphylococcus

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What causes accumulation of fluid in the intestines resulting in diarrhea in neonatal pigs?

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E.coli enterotoxin

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Example of thermophilic bacteria ?

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bacteria that grow at 45 degrees C, like C. jejuni

Front 30

How does Staph aureus resist action of penicillin?

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It produces beta-lactamase which destroys the beta-lactam ring of penicillin --> inactivation.

Front 31

What are some immunological techniques used to diagnose bacterial disease?

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* Bacterial agglutination for antibodies.
Latex particle agglutination for bacterial antigens. Fluorescent Ab testing. ELISA Stereotyping of bacteria.
Delayed hypersensitivity.

Front 32

Name components of bacterial outer envelope.

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Capsules,Flagella,
Adhesins (pili and non pili)
Outer membrane (gram negative only)
Periplasmic space (lipoprotein and peptidoglycan)
Cell wall,
Inner membrane (cytoplasmic membrane)
Spores

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What bacteria produce spores?

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Clostridium and Bacillus (oblig. or facultative anaerobes)

Front 34

Catalase test

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If possess catalase (i.e.catalase +), when a small amount of bacteria is added to H2O2 bubbles of oxygen are observed.

* If bubbles or froth forms, the organism is said to be catalase-positive. Staphylococci and Micrococci are catalase-positive.
* If not, the organism is catalase-negative. Streptococci and Enterococci are catalase-negative.

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What medium is most commonly used, is enriched, and helps to recognize hemolytic reactions?

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Blood agar (BA)

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What is an example of a primary pathogen?

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Chlamydophilia felis (conjunctivitis in cats)
* Primary pathogens cause disease in normal, healthy host,

Front 37

What large capsulated rod has spores that are highly resistant and inhalation can lead to a rapidly fatal disease?

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Bacillus anthracis:
* Gram-positive spore-forming, rod-shaped bacterium
* grown in ordinary medium under aerobic or anaerobic conditions

Front 38

What can be used to test for tuberculin in cattle?

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Delayed hypersensitivity.

Tuberculin is a protein extract from Tuberculosis; injected subcutaneously, macrophages will rush to area if have been exposed to it. (expand on this)

Front 39

What drugs are not suitable for taking orally?

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Penicillin G (destroyed in stomach) Aminoglycosides like Gentamicin (not absorbed from GI)

Front 40

What part of the cell wall gets stained with Gram staining and how does this effect the color?

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peptidoglycan

Peptidoglycans are stained. Gram + bacteria have thick layer which retains stain, while the Gram - bacteria which has thin layer making it ____

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These are slender and don't stain well with Gram. They are usually visualized with Giemsa or silver stain.

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Spirochetes (like Leptospira)

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The cell wall contains lipids and wax-like substances (mycolic acids) that make Gram stains poor. This group is visualized with acid-fast stain methods.

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Spirochetes (like Leptospira)

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What chemical sterilization agents kill spores?

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Formaldehyde (disinfectant gas)
Iodines (halogen) at right pH.
Ethylene oxide (sterile gas) to some extent.

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How are bacterial capsules visualized?

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Negative staining protocol such as:
India ink
Nigrosin

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What kind of media does M. tuberculosis require?

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Egg media with supplements. NOT blood agar.

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What disease is caused by E.coli and belongs to different serotypes which produce "Shinga toxin" which damaged blood vessels and kidneys?

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Hamburger disease

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What are two antibiotic sensitivity test that involves disc diffusion?

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1. disk diffusion (Kirby-Bauer) method

2. Disk diffusion method: Mueller-Hinton agar w/o blood and with blood

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How can you visualize bacteria with no cell wall like mycoplasma?

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Giemsa stain (rings) Electron micrograph Silver stain

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Is broth media used for routine culture?

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No

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Are peracetic acid and chlorine dioxide tuberculocidal?

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Yes

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What are four penicillin susceptible organisms?

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Corynebacterium
Streptococcus (most)
Erysipelothrix (obscure gram+ rod)
Clostridium (most)

Front 52

How can Amoxicillin be made resistant to beta lactamase enzyme?

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Amoxacillin-clavulanic or "Clavamox" (potentiated amoxicillin)

note: Clavamox no good for pseudomonas

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What is known as a selective/differential medium and selectively grows enteric and other Gram negative bacteria?

How does it differentiate between gram negative bacteria?

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MacConkey agar

can differentiate those bacteria that are able to ferment lactose.

Can differentiate between bacteria able to ferment lactose, Bacteria able to ferment lactose, create acidic pH, turn pink (neutral is red or natural color).
Examples of lactose ferm. genera include Escherichia, Klebsiella, Enterobacter.

Pseudomonas turns green for some reason

Front 54

What are two examples of contagious diseases?

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Strangles in horses (Streptococcus equi Pneumonic plague (Yersinia pestis) in cats --> contagious to other cats and humans.

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What is the order of bacteria in terms of survival in a favorable environment?

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Mycoplasma (3 days), Leptospira (10 days), Mycobacterium bovis (6 months)
Salmonella (8 months)
Brucella (8 months)
Fungal spores (10 months), Bacillus anthracis (over 50 yrs in soil).

Front 56

What methods can be used for susceptibility testing of antibiotics?

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Broth dilution Kirby-Bauer disc diffusion method E-test (gives MIC)

Front 57

What kind of transmission occurs with spread due to contact, food, water, etc.?

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Horizontal transmission

Front 58

What is the term for the degree of pathogenicity, which a bacteria may lose or gain?

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Virulence Example: capsules

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During this phase many bacteria remain viable, but non-culturable.

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Death/decline phase

Front 60

What is a commercial disinfectant that is bactericidal and fungicidal, to which mycobacteria and clostridial spores may be resistant?

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Virkon

Front 61

Give an examples of branching bacteria.

What do they have in common?

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Actinomyces (gram +) Nocardia (gram +)

Also Dermatophilus, (gram +), skin disease causing organism, may appear like “railroad track’

Front 62

Identification of antibody against Brucella done via ?

Name of other agglutination test ?

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Bacterial agglutination test e.g. for Brucella (gr- rod)
-> not something like otitis external which is easily assessable

Latex bead agglutination test: beads coated with aB or antigen and it's counterpart in sample "agglutinates"

Front 63

Give 2 examples of spiral bacteria

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Leptospira
Borellia burgdorferi (lyme disease)

Front 64

What broad spectrum penicillin is susceptible to the beta-lactamase enzyme?

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Amoxicillin

Front 65

What __ do not need susceptibility testing because they are predicatable (susceptible to penicillin)?

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Cornyebacterium Erysipelothrix Bacillus

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Anthrax.sterilization

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Formalin 5% spray should be exposed for 4 hours

Front 67

These are slender and don't stain well with Gram. They are usually visualized with Giemsa or silver stain.

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Spirochetes (like Leptospira)

Front 68

What bacteria show bipolar staining?

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Pasteurella

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Gram+ cocci which grows in bunches?

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Staphylococcus aureus

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What type media for Staphylococcus ?

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Blood agar

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What is used to differentiate between Staphylococcus and Streptococcus?

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Catalase test: H2O2 added, only see bubbling with Staphylococcus, not with Streptococcus!

(both are gram+ cocci; staph in bunches and strep in chains)

Front 72

Is blood agar a selective medium?

Back 72

No, because many bacteria grow on this, but Stephy

Front 73

Pleomorphic gram positive rods that look like “Chinese letters”?


Drug of choice?

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Corynebacterium, can be curved, clubbed shaped, etc


Penicillin (even Penicillin G)

Front 74

Are Dry swabs are suitable for sample collection?

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NO

Front 75

What is direct smear used for?

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Staining (gram or acid-fast), b/c anaerobic bacteria will not grow on standard blood agar. Need to fix and stain immediately.

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Klebsiella can cause ____ in dogs, and ___ in horses

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Klebsiella can cause otitis externa in dogs, and genital tract infections in horses

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Rappaport or selenite broth is used for?

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* isolate organisms such as Salmonella from fecal sample
* The ingredients in these media suppress E. coli and enterics other than Salmonella.
* After 18 hrs incubation subculture is done on BA and Mac agar plates.

Front 78

Name some virulence factors:

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Pilli
LPS (in gram-)
capsule (Streptococcus pneumoniae)

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What are some methods by which bacteria can acquire virulence factos?

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- Transformation
- Transduction
- Conjugation
- via bacteriophage (e.g. shiga toxin)
- from free DNA floating

Front 80

Do all anaerobic bacteria form spores?

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No, Fusobacterium do not.

Front 81

Fusobacterium are resistant to?

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Enrofloxacin (Fluoroquinolones) resistant
- in fact all anarobes are!

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After isolation and identification of bacteria, ____ is done

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After isolation and identification of bacteria, antibiotic sensitivity testing is done.

Front 83

If dog will be used for breeding and you want to test for Brucella canis, but its not showing symptoms and cannot be diagnosed via culture. What do you do?

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serological tests, take serum and look for antibody

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Obligate pathogen?

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Bacillus anthracis
Mycobacterium tuberculosis

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Opportunistic pathogen

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commensal bacteria which is normally not pathogenic, but can be under right conditions
e.g. Staphlococci as eye mucosa destroyed by mycoplasma or Chlamydia, staph cause sec.infection. OR streptococcus in GI when Chlamydia infects down there.
OR if bacteria from GI gets into UT

opportunistic = secondary

Front 86

Where does Brucella usually infect?

Back 86

urogenital tract, more specifically uterus, epididymis, testicles

Front 87

What should never be given to rabbits?

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penicillin

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What is risk of using drugs like Penicillin and Cephalosporins?

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Lyse cell wall, so if use on cow which has mastitis (infection of mammary gland) from E.coli infection or any gram (-) bacteria endotoxins get into circulation, kills animal.

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Narrow spectrum penicillin?

Broad spectrum penicillin?

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penicillin G

Ampicillin
Amoxicillin

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Beta- lactamase enzymes inhibitor?

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Sulbactam and Clavulanic acid
inactivate β lactamase of bacteria

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Good for Rickettsia or Ehrlich?

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Tetracycline (Doxycycline)

note: these are bacteria commonly associated with ticks

Ehrlichiae are a group of small, gram-negative, pleiomorphic, obligate intracellular cocci that infect different blood cells in various animal species and in humans.

Front 92

Brucella canis

Back 92

Tetracycline