Veterinary Microbiology Flashcards

Vocabulary flashcards based on lecture notes about veterinary microbiology.

Lytic Phage

Lytic phages take over machinery of the cell to make phage components, then destroy the cell to release new phage.

Lytic Cycle Steps

Attachment → Tail binds to receptors on cell on bacterial cell, Penetration → phage injects DNA into cytoplasm of bacteria, Biosynthesis → phage DNA replicates and phage proteins are made, Maturation → assembly of new phage, Release → cell lysis

Lysogenic Phage

Lysogenic phages incorporate their nucleic acid into the host chromosome and replicate without destroying the cell.

Lysogenic Cycle Stages

Attachment, Penetration, Prophage, Cell division

Clostridia

Large, gram (+) rods/bacilli with one exception → c.piliforme is gram (-), produce endospores, anaerobic, catalase (-), oxidase (-), Present in soil, alimentary tract if animals & faeces.

Neurotoxic Clostridia

c.tetani, c.botulinum

Histotoxic Clostridia

c.chauvoei, c.perfringens (type A)

Enteropathogenic & enterotoxaemia-producing clostridia

c.perfringens (types A-E)

Atypical Clostridia

c.piloforme

Bordetella

Gram (-) rods, catalase (+), oxidase (+), symptoms usually relate to upper respiratory tract infections, young animals are most susceptible, infections in adults are usually mild or subclinical, stress and concurrent infections are predisposing factors to outbreaks, morbidity rates are high yet mortality rates are low

b.bronchiseptica

atrophic rhinitis in su, kennel cough in dogs

b.avium

birds, turkey coryza rhinotracheitis

b.pertussis

humans whooping cough

b.parapertusis

humans & lambs, mild whooping cough, chronic pneumonia in lambs

Superficial & Cutaneous Mycoses

affect skin, hair, nails

Examples of Superficial & Cutaneous Mycoses

Pityriasis versicolor, Tinea nigra, White/Black piedra, Seborrheic dermatitis

Agents of Superficial & Cutaneous Mycoses

Malassezia, Candida, Trichosporon, Hortaea, Dermatophytes, environmental moulds

Mucosal Mycoses

affect mucous membranes

Agents of Mucosal Mycoses

Candida, Trichosporon, Rhodotorula

Subcutaneous Mycoses

chronic local infections of deeper skin layers

Agents of Subcutaneous Mycoses

Sporothrix schenckii, environmental molds/yeasts; may follow trauma or spread

Opportunistic Systemic Mycoses

in immunocompromised hosts

Agents of Opportunistic Systemic Mycoses

Candida, Cryptococcus neoformans, Aspergillus

Invasive Systemic Mycoses

often generalised, may affect healthy or weak hosts

Agents of Invasive Systemic Mycoses

Dimorphic fungi (endemic), Cryptococcus (opportunistic)

Antibiotic resistance

Means that bacteria have a mechanism making therapeutic treatment impossible despite high doses of antibiotics. The resistance can be innate (chromosomally encoded) → decreased cell permeability or acquired (random mutation) → degradation of beta lactams antibiotics by genes encoded on plasmid in some bacteria.

Virulence

is the ability to cause disease. It is measured by the number of infectious agents to cause disease or death.

Examples of virulence factors

pili, fimbriae & Protection against phagocytosis → capsules, toxins

Gram stain

a differential stain that allows us to distinguish Gram (+) from Gram (–) bacteria. Add crystal violet stain 2 mins → stains both gram (+) and (–) purple, Wash and add iodine for 2 mins → both stay purple, Wash and add alcohol for 30 secs → decolourises gram (-) due to thin cell wall, gram (+) still purple due to thick cell wall, Wash and add fuchsin for 30 secs → gram (-) goes pink/red, gram (+) stays purple

Mycobacteria

Gram (+) rods, non-motile, aerobic, catalase (+), acid fast, non-spore forming. High lipid content in the cell wall, particularly mycolic acids, which is responsible for their acid-fast staining properties

M.bovis

the causative agent of bovine tuberculosis. It causes a chronic respiratory disease characterized by granuloma formation in the lungs and lymph nodes.

M.avium subsp. paratuberculosis

causes Johne’s disease, a chronic granulomatous enteritis in ruminants, leading to diarrhea, weight loss, and malabsorption over time.

Endotoxins

LPS of outer membrane in gram (-) bacteria, release upon lysis, weaker effect, non-specific symptoms, heat stable

Exotoxins

released outside the cell, polypeptides released by growing bacteria - mainly gram (+), stronger effect, specific symptoms, most are not heat stable, high toxicity and immunogenicity

Horizontal gene transfer

the transfer of genetic material from one organism to another which is not an offspring

Conjugation

transfer of genetic material (usually bacterial plasmid) between bacteria via direct cell-cell contact

Transformation

uptake of "free" DNA in environment, which is encorporated into bacterial genome

Transduction

phage mediated transfer of host bacteria genetic material, during a viral infection the virus can pick up genetic information from the bacterial cell, which is then transferred to another cell when phage infects it

Cell wall synthesis antibiotics

Target: peptidoglycan, Class: β-lactams (penicillins), glycopeptides (vancomycin)

Cell membrane antibiotics

Disrupt integrity, Class: polymyxins, lipopeptides

Protein synthesis antibiotics

Target ribosomes, 30S: aminoglycosides, tetracyclines, 50S: macrolides, lincosamides, chloramphenicol

Nucleic acid synthesis antibiotics

Block replication/transcription, Class: fluoroquinolones (DNA gyrase), rifamycins (RNA pol)

Folic acid pathway antibiotics

Block metabolic enzymes, Class: sulfonamides, trimethoprim

Staphylococcus

Gram (+) cocci in clusters, Oxi (-), Cat (+) → except s.aureus subsp., facultative anaerobe, non-spore forming, non-fastidious, round, medium sized white-yellow colonies

S. aureus subsp. Aureus

food poisoning in humans, mastitis

S. aureus subsp. Anaerobius

morels disease

S. pseudintermedius

pyoderma and otitis externa in dogs

S. hyicus

arthritis in pigs

Bacillus

Large gram (+) rods, endospore fomring, non-fastidious, most are motile, catalase (+), oxidase (-), aerobic or facultatively anaerobic. Found in soil, water, environment → many are saprophytic

Bacillus anthracis

obligate, causes anthrax in cattle, sheep, goats. Spores enter via wounds, inhalation, ingestion. Virulence factors: capsule (antiphagocytic), tripartite exotoxin (protective antigen, edema factor, lethal factor)

Bacillus cereus

opportunistic pathogen. Causes food poisoning in humans. Occasionally causes mastitis in cattle.

Pasteurella

gram (-) rods/ coccobacilli, non-motile, facultatively anaerobic, catalase (+), oxidase (+), fastidious, ferment sugars, grow on MacC, present in mucous membranes, upper respiratory tract & GIT.

P.multocida

causes fowl cholera.

Manhaemia

gram (-) rods, non-motile, facultatively anaerobic, catalase (+), oxidase (+), fastidious, ferment sugars, don't grow on MacC, present in mucous membranes, upper respiratory tract & GIT, mainly isolated from ruminants, upper respiratory tract disorders.

M.haemolytica

bovine pneumonic pasteurelliosis (shipping fever).

M.granulomatis

bronchopneumonia, conjunctivitis.

Dermatomycoses

general term for fungal infections of the skin, hair, and nails. Caused by various fungi, including yeasts and molds (not limited to dermatophytes).

Etiological Agents of Dermatomycoses

Candida spp. → opportunistic yeast infections (e.g. Candida albicans), Malassezia spp. → common in dogs (e.g. otitis externa, dermatitis), Aspergillus spp. → can cause cutaneous aspergillosis, Other environmental molds

Dermatophytoses/Ringworm

contagious superficial fungal infections of keratinized tissues (skin, hair, claws)

Etiological Agents of Dermatophytoses

Microsporum spp. (M.canis → cats and dogs), Trichophyton spp. (T.mentagrophytes)

Animal viruses

Unique infectious agent, that is very small, only contains DNA or RNA and has absolute dependence on a host cell for survival.

Characterize prokaryotic cells

Cell wall, some have capsule → protect and maintain shape, Singular circular chromosome as nucleoid in cytoplasm (not membrane bound), DNA in plasmids → carry extra gene that can enhance cell survival such as one for antibiotic resistance, Mesosomes in cell membrane → cellular respiration, Ribosomes → synthesis proteins, Some have flagella and fimbriae → locomotion, Lack ER and GA

Aim of PCR

PCR (Polymerase Chain Reaction) is used to amplify specific DNA sequences, allowing rapid detection of pathogens in diagnostic microbiology, monitoring of lab animals, contamination screening in cell cultures, and disease diagnosis.

Antibiotic

Means that bacteria have a mechanism making therapeutic treatment impossible despite high doses of antibiotics.

Streptococci

Gram (+) cocci in chains, Catalase (-), non-spore forming, fastidious, facultative anaerobes, small, usually haemolytic, translucent colonies.

Enterococcus

enteric streptococci that live in the intestinal tracts of humans & animals, cells are bigger & oval compared to streptococci.

E. coli

pathotypes group strains that have the same pathogenicity in host.

E. Coli Pathotypes

ETEC – enterotoxigenic e.coli, EPEC – enteropathogenic e.coli, EIEC – enteroinvasive e.coli, EAEC - enteroaggregative e.coli, EHEC – enterohaemorrhagic e.coli.

Virulence factors of E. coli

Capsule, LPS, Adhesins → fimbriae, Toxins.

Virulence factors of p. aeruginosa

Pili, flagella, LPS, Exopolysaccharides, exotoxin S, T, A, Y, U Enzyme for bacterial cell to cell interaction, serine protease, zinc metalloprotease, phospholipase C

Opportunistic Infections of Pseudomonas Aeruginosa

They are an etiological agent for opportunistic infections as they can adapt & survive in a wide range of environments, & can utilise a wide range of nutrients. They can also survive in liquids which has become problematic in hospitals and vet clinics.

Yeast

unicellular fungi, replicate by binary fission or budding, cause superficial and deep mycoses as well as opportunistic infections.

Mycelial

multicellular forms, colonies formed of many hyphae, molds low virulence, dermatophytes cause dermatophytoses

Dimorphic fungi

they can be both morphological forms; yeast and mycelium depending on environmental conditions.

Moulds Virulence factors and predisposing factors

Immune system is compromised → AIDs, Diabetes, cancer, Environmental spp gets into wounds, Warm and damp environments enhance the growth of molds meaning more of them present.

Viral replication

Attachment & entry to cell, Synthesis of viral specific proteins, Production of new viral nucleic acids, Assembly of new viral particles, Release by cell lysis.

Catalase test

is used to determine if a bacteria has catalase

Bacterial plasmid

Small, circular piece of DNA that exists independently of the bacterial chromosome. It helps bacteria by carrying genes that can provide advantages, such as Ab resistance, toxin production, or the ability to metabolize unusual substances, aiding in survival and adaptation.

Bacteria causing bovine mastitis

Contagious mastitis → staph. Aureus, strep. Agalactiae, Environmental mastitis → strep. Dysgalactiae & agnetis, e. coli, Summer mastitis → trueperella pyogenes

Animal virus

Unique infectious agent, that is very small, only contains DNA or RNA and has absolute dependence on a host cell for survival.

Yeast

unicellular fungi, replicate by binary fission or budding, cause superficial and deep mycoses as well as opportunistic infections.

Mycelial

multicellular forms, colonies formed of many hyphae, molds low virulence, dermatophytes cause dermatophytoses

Dimorphic fungi

they can be both morphological forms; yeast and mycelium depending on environmental conditions. True pathogenic dimorphic fungi → yeast in the host and mycelium in the environment or at 24ºC. → eg. Histoplasma capsulate, Blastomyces dermatidis, coccidiodes immitis, Opportunistic dimorphic fungi – fungi that are able to invade host by changing from saprophyte to parasite due to change in morphological form

Horizontal gene transfer & methods

Horizontal gene transfer is the transfer of genetic material from one organism to another which is not an offspring. Conjugation → transfer of genetic material (usually bacterial plasmid) between bacteria via direct cell-cell contact, Transformation → uptake of "free" DNA in environment, which is encorporated into bacterial genome, Transduction → phage mediated transfer of host bacteria genetic material, during a viral infection the virus can pick up genetic information from the bacterial cell, which is then transferred to another cell when phage infects it.

E. Coli

coliforms are defined as lactose fermenters with the production of acid and gas

Pasteurella

gram (-) rods/ coccobacilli, non-spore forming, non-motile, facultatively anaerobic, Oxi (+), Cat (+), fastidious, ferment sugars, doesn't grow on MacC!!, present in mucus membranes, upper RT & GIT.

MIC and MBC

MIC = Minimal inhibitory Concentration → The lowest concentration of antibiotic required to inhibit the growth of bacteria, MBC = Minimum Bactericidal Concentration → The lowest concentration of antibiotic required to kill 99.9% of original inoculum.

clostridium tetani

causative agent of tetani

Replication of viruses in animal cells

Viruses replicate by: Attachment & entry to cell, Synthesis of viral specific proteins, Production of new viral nucleic acids, Assembly of new viral particles, Release by cell lysis.

Dimorphism in fungi

They can be both morphological forms; yeast and mycelium depending on environmental conditions. True dimorphic fungi are yeast in the host and mycelium in the environment or when cultured at 24ºC. → E.g. histoplasma capsulata, coccidiodes immits and Blastomyces dermatiditis, Opportunistic dirmorphic fungi are ones which invade the host by changing from saprophytic to parasite, along with a change in morphology. → E.g. candida albicans.

Oxidase test

used to determine if bacteria contains cytochrome c oxidase

Methods of gene modification

Transformation → uptake of foreign DNA (often plasmids) from the environment by a bacterial cell, Transduction → transfer of DNA from one bacterium to another via a bacteriophage (virus), Conjugation → direct transfer of DNA between bacteria through a pilus (usually involves plasmids like F-plasmid)

Pasteurella

Pasteurella → Gram (-) rods/ coccobacilli, non-spore forming, non-motile, facultatively anaerobic, Oxi (+), Cat (+), fastidious, ferment sugars, doesn't grow on MacC!!, present in mucus membranes, upper RT & GIT. p. multocida → fowl cholera, snuffles in rabbits, pneumonia and septicaemia in cattle., p. caballi → pneumonia in horses

Components of prokaryotes and describe their roles

Cell wall, some have capsule → protect and maintain shape, Singular circular chromosome as nucleoid in cytoplasm (not membrane bound), DNA in plasmids → carry extra gene that can enhance cell survival such as one for antibiotic resistance, Mesosomes in cell membrane → cellular respiration, Ribosomes → synthesis proteins, Some have flagella and fimbriae → locomotion, Lack ER and GA.

Endotoxins

LPS of outer membrane in gram (-) bacteria, release upon lysis, weaker effect, non-specific symptoms, heat stable

Exotoxins

released outside the cell, polypeptides released by growing bacteria - mainly gram (+), stronger effect, specific symptoms, most are not heat stable, high toxicity and immunogenicity

Qualitative

to determine if a bacteria is susceptible or resistant to an antibiotic

Quantitative

to determine MIC

How ability to ferment lactose can distinguish Gram (–) rods and how

Ability of gram (-) rods to ferment lactose can useful in reducing the number of possibilities a bacteria could be as only some Gram (-) rods have the ability to ferment lactose. MacConkey agar contains bile salts and crystal violet which are inhibitors of gram (+) bacteria, thus prevents their growth, so only Gram (-) will grow. It also contains lactose, AAs and a pH indicator → used to determine if a bacteria is lactose (+) or (-)

Staphylococci

Gram (+) cocci in clusters, Oxi (-), Cat (+) → except s.aureus subsp. anaerobius, facultative anaerobe, non-spore forming, non-enriched media, round, medium sized white-yellow colonies