Flashcards
Bacteriology
Cards in this deck (139)
- 1Koch's postulates1. Must find the same pathogen in each diseased pathogen
2. Isolate pathogen in culture
3. Infect healthy pathogens
4. Re-culture the same pathogen in the newly diseased animals
Exceptions: immuno-suppressed animals - 2Bacterial classificationsProtists
Usually unicellular
Prokaryotes - 3ProtistsAll bacteria, protozoa and fungi
- 4Higher vs lower protistsHigher: eukaryotic
Lower: prokaryotic - 5EukaryotesHave a true nucleus
. - 6ProkaryotesNo true nucleus, condensed chromatin
- 7Sub-division of bacteriaGenus and species
Morphologt
Stain
Oxygen requirement
spore formation - 8Typical bacteria sizeMost extra-cellular
1-5 microns by 0.2-2 microns - 9Two principle morphologiescocci - round
(diplo, strepto, staph, and sarcinae)
bacilli - rod like
(coccobacilli, vibrio, spirilla, spirochete) - 10Bacterial structureCell wall: shape, protection and antigens
-rigid
-surrounds cytoplasmic membrane
-anchors pili, flagella and capsule
Gram - or + - 11Gram +2 layers: cell membrane and pep.
Thick peptidoglycan with teichoic and lipoteichoic acids - 12Gram -3 layers
cell membrane
thin peptidoglycan later
phospholipids, lipoproteins and lipopolysaccharide layer - 13Space in gram + bacteria wallperiplasmic space
- 14LPSNon permeable structure
In gram - bacteria
Actively creates transmembrane pores for transport of substances
Has lipid A molecules - cause septic shock. Don't lyse cells for treatment, prevent replication instead - 15Gram stainingMake smear
heat fix and dry
Stain with crystal violet
Fix stain with iodine
Decolourise with alcohol (removes LPS)
Counter stain with safranin red
Most accurate in exponential growth phase - 16Gram positive stained bacteriaPurple
retain crystal violet
PURPLE POSITIVE - 17Gram negative stained bacteriaStain pink/red
- 18Cytoplasmic membraneLipid bilayer between the two protein laters
Semi permeable
Involves in cell processes
Involved in endospore production! - 19Cytoplasmic contentsDNA haploid chromosome
Inclusion bodies: storage
Ribosomes: protein synthesis
Plasmids - circular non chromosomal DNA
(used to exchange genes) - 20Additional structures on bacteriaFlagellum: increase movement
Capsule or slime layer: allows for adhesion
Pilus / fimbria: stick between tight junctions of cells
Conjugation pili: movement of plasmids - 21CapsulesGlycocalyx
Slime layer attached to cell wall that is gelatinous. Comprised of polysaccharides and polypeptides
Allows for adhesion
Protects against phagocytosis
Present in biofilms (such as plaque) - 22FlagellaWhip like structures for locomotion
Can visualise motility in liquid or semi-solid medium
Can have multiple flagella - 23Pili/fimbriaeFine filamentous appendages to anchor between cell junctions
Mostly in gram negative bacteria
Long conjugation pilli for exchange of genetic material (plasmid) - 24EndosporesResistant, dormant survival form of the bacteria produced in bacillus and clostridium species
Highly resistant to high temperatures, boiling, disinfectants and drying
Can stay in dormant spore for ages until a suitable environment is available - 25AntigensProteins: exotoxins or enzymes
Lipopolysaccharies on cell wall
Carbohydrates on capsules
Used for identification and for stimulating the host immune system (vaccines) - 26ExotoxinsProtein secreted from a living bacterium released on lysis and injected into cells by the bacteria
Damage the host by destroying cells and disrupting cell metabolism.
Highly potent and causes systemic disease - 27EndotoxinsLPS in the cell wall of gram negative bacteria (Lipid A)
Results in fever, leukopenia and DIC
Stimulates macrophages, induces cytokines, TNF and IL-1 release
C. tetani and C. botulinum - 28EnterotoxinsHost cell dealth or damage from nacteria that bind the small intestine cells. Cause electyolyte loss and enzymes
C. perfringens - 29Hydrolytic enzymesActively destroy RBC membranes causing inflammation
Strep pyogenes
Staph. aureus - 30Binary fissionCell elongates
Transverse membrane formed
New cell grows inward and nuclear material distributed
Cell membrane constricts forming new cells or chains/clumps (partial or full cleavage) - 31Bacterial growth in ideal conditionsGrowth is increase in numbers rather than size
double every 20 minutes
grow in liquid or semi-solid media - 324 phases of bacterial growthLag: environmental suitability and prep for replication
Log / exponential: active replication
Stationary: equal number of cells replicating and dying
Death: more bacteria dying then replicating - 33Bacterial coloniesStart as a single organism and form a small heap of organisms
- 34Requirements for growthCarbon: carbs, lipids and peptides
Nitrogen
Growth Factors: coenzymes
Inorganic salts: Phosphate, N, S, K, Mg, Fe, Ca - 35Enrichment mediaBlood agar
Additional growth factors have been added
WIll grow most things - 36Selective mediaDesigned to suppress the growth of some microbes and allowing others. Can add antimicrobials, salts and dyes.
Eg. restrict gram - or gram + - 37Differential mediaAllows growth of more than one microbe. Morphologically distinguishable colonies
- 38Physical conditions for growthOxygen required for aerobes
Obligate anaerobes: grow only with no oxygen (gut and rumen)
Facultative anaerobes: can grow with or without oxygen - 39Temperature for growthMesophile: grow best at 25-45 degrees
Thermophile: optimum growth between 45-70 degrees - 40Methods of controlling infectionHeat (autoclaves)
Moist cycles: can't kill capsuled organisms or spores. Use dry cycle for these. - 41AntisepticNon selective chemical applied to skin or surfaces to kill micro-organisms
- 42Intrinsic resistanceProperty of the organism which involves chromosomal genes resulting in an impermeable cell wall or development of an alternative biochemical pathway
- 43Acquired resistanceOccurs after exposure to a drug and is due to a mutation in the bacterial DNA sequence or the acquisition of foreign DNA via plasmids
- 44Disc susceptibility testDiscs with different antibiotics and concentrations placed over plates with bacteria on them
Antibiotic diffuses through the agar
Measure the diameter of nil growth to measure the susceptibility - 45Factors of normal skin that prevent unwanted colonisationDry
Lactic acid produced in sweat and by normal skin flora
Lipids, lysozymes and defensins
Physical removal via sloughing dead keratinocytes
Skin is normally cooler than inner body temp - 46Role of normal skin floraSkin flora outcompetes pathogens and better at replicating
Secrete chemicals against pathogens
Stimulate the skin's immune system - 47Important bacteria+: staphylococcus and streptococcus (resident)
-: E. coli, pseudomonas (transient)
Yeast: candida and malasezzia - 48StaphylococciGram positive, In pairs or clumps
Catalase positive
Non motile and non spore forming
Coagulase test correlates with pathogenicity
Normally in skin and mucus membranes, opportunistic infections - 49Staphylococci infectionsMastitis
UTIs
Greasy pig
Septic arthritis
Toxaemia due to enterotoxins: severe diarrhoea, nausea and vomiting - 50Diagnosis of staphylococcus infectionSample
Gram stain
Catalyse test
coagulase: positive is pathogenic
Haemolysis of blood agar indicates a pathogenic staphylococci - 51Treatment of staphylococcusMethicillin or B-lactam
MRSA is common - needs Vancomycin - 52StreptococcusColonise mucus membrane in nose and throat
Gram positive chains
Catalase negative
Haemolysis in blood agar: partial, complete or non - 53Streptococcus habitatsLactic - in cheese
Viridans: resident of resp and GI tract
Pyogenic: pathogenic - 54Streptococcus infectionsMastitis
Stangles
Septicaemia and respiratory infection
Meningitis - 55Diagnosis of streptococcusGram stain
Catalase negative
Biochemical tests
Haemolysis: indicates pathogenic - 56Treatment of sreptococcusLess resistant than staph
Use penicillin or B lactams
Isolate sick animals
Decontaminate the environment - 57Common gram negative bacteriaSalmonella and E.coli
Enterobacteriaceae
Live in the gut - 58Enterobacteriaceae characteristicsGram negative
Rods,Facultative anaerobes
Motile via flagella, Non spore forming
+/- capsules and pili (pathogenicity traits)
Resistant in environment susceptible to disinfectants, grow at 37 degrees
Oxidase negative
Ferment glucose -> acid and gas (TSI slants) - 59Transmission of disease in enterobacteriaceaeIngestion of contaminated food and water
Endogenous UTI
Environmental - mastitis - 60Selective and differential mediaMacConkey - will grow gram -ve
Selective: inhibits gram positive
Differential: lactose fermenters are pink and non lactose fermenters are creamy
XLD - black colonies are salmonella - 61EndotoxinsLPS (Lipid A) component of cell wall stimulates immune system and causes septic shock, DIC and fever
- 62EnterotoxinsCytotonic and cytotoxic
- 63Cytotonic enterotoxinsDo not damage cell integrity
Secreted into the intestinal lumen and absorbed by cells resulting in severe fluid loss - 64Cytotoxic enterotoxinsDamages cell and vascular endothelium resulting in oedema, haemorrhage and thrombosis
Bloody diarrhoea - 65Virulence factorsCapsules
Attachment pilli (overcome peristalsis)
Iron uptake systems - lyses RBCs to use iron - 66Antibiotics, management and treatmentResistance from plasmids
Use antibiotics that do not cause lysis - prevents excess release of Lipid A and shock
Improve husbandry, reduce stress and improve immunity via colostrum and vaccines - 67Host immunity to gram negative bacteriaBacteriostatic antibiotics best, allows host immune system to remove the infection
Humoral immunity - IgA - 68E. coliGram - rids
Ferment lactose
Pink on XLD
Commensal in intestines and rumen
Found in the environment and soil
opportunistic infections from faecal contamination. Mastitis, septicaemia and UTI - 69ETECTrue E.coli pathogens
Neonatal diarrhoea - calf scours - 70VTECE.coli
Food borne disease and bloody diarrhoea - 71Calf ETEC diarrhoeaCalf scours: Watery diarrhoea caused by E.coli K99, Usually in first 5 days of life
- milk reduces stomach pH, allows establishment of bacteria in the gut
-Immature intestinal flora
-Enterocytes have K99 receptor when immature
Diagnosis via ELISA or post mortem - 72E.coli diagnosisGram stain
Oxidase negative - 73Treatment of calf scoursIsolation of sick animals
Rehydration
Appropriate antibiotics - 74Prevention of calf scoursVaccinate Dams
Ensure adequate passive transfer via colostrum - 75Coliform mastitisRapid onset acute systemic illness
Environmental cause of mastitis
Common for indoor housed cattle
Common during calving and drying off
Udder swelling, watery milk and white flakes in the milk
High fever, endotoxaemia and diarrhoea - 76Diagnosis of coliform mastitisMastitis score +3
Coliform culture from milk
SCC - 77Treatment of coliform mastitisBroad spectrum IV antibiotics
NSAIDs
Fluids
Strip infected quarter
teat seal
Improve environment hygiene - 78SalmonellaGram negative, facultative anaerobes
Do not ferment lactose
Motile and non spore forming
ZOONOTIC
Colonises the intestinal tract
Sub-clinical animals are carriers and reservoirs of salmonella
Persist in the environment for 9 months - 79Transmission of salmonellaCalves: from other calves in poor hygiene
Contaminated feed via rodents, birds and insects
Humans, equipment and vehicles can introduce salmonella to animals - 80Salmonella diseaseEnteritis and foul smelling watery diarrhoea. Death from dehydration
Meningitis and polyarthritis
Septicaemia: fever inappetence, depression and rapid death
Abortion in pregnant animals that develop septicaemia - 81DiagnosisFaecal material or tissue
Gram stain
Oxidase negative
TSI
XLD media: black colonies - 82VISERTherapy control method
Vaccination of dams
Isolation of sick
Stress to be reduced
Eliminate infection sources
Reduce exposure to faecal contamination (feed and water soures) - 83Salmonella treatmentBroad spectrum antibiotics - culture and sensitivity
Fluid therapy
Leave calves on milk but supplement electrolytes - 84VaccinationsVaccinate dams 2-4 weeks pre parturition
Vaccinate neonates for E.coli if desperate - 85Leptospira characteristicsHelical, coiled bacteria
Gram negative but doesn't stain well
Visualised by antibodies and fluorescence
Aerobic, facultative and obligate anaerobes
Complex nutrition requirements so hard to culture - 86Leptospira structureInternal flagella that run the length of the organism
Movement and coiling via contraction and relaxation of flagella - 87Where are leptospira foundZoonotic: in humans and animals
Common in pigs, cattle, sheep, horse, goats and dogs
Maintains in host adapted environment: each lepto has a specific host and will only cause mild disease.
Non-host adapted serovar: significant clinical disease in unintended host - 88Non-host adapted acute diseaseSEVERE
Septicaemia, organ failure, abortion, hepatitis, meningitis - 89Chronic diseaseAn issue in host adapted serovars
Abortion and stillbirth
Acute disease symptoms not present - 90Epidemiology of leptospiraEach serovar has a host-adapted maintenance host that it causes limited disease in (nephritis and fertility)
Maintenance host transmission to accidental host causes significant, acute disease - 91HardjoCattle
- 92PomonaPigs
- 93CopenhageniRats
- 94Lepto in dogsCopenhageni
Accidental host, pick it up from rats
Acute interstitial nephritis and liver damage - 95Diagnosis of leptoClinical signs
Microscopy - multiple sections
Serology: agglutination and increasing titre across multiple samples - 96TreatmentStreptomycin to clear maintenance animals and reduce lesions + clinical signs
Penicillin in humans - 97PreventionPPE!
Reduce contact with urine - 98ControlIdentify and eliminate maintenance hosts of non host adapted
Increase herd immunity and reduce transmission of host adapted
Good hygiene to prevent environment contamination
Isolate infected animals and prevent mixing
Rodent control - 99Campylobacter characteristicsGram negative, helical, motile, micro-aerophilic
Pathogenic or a commensal of the reproductive, oral and intestinal tract
Zoonotic! common in birds - 100C. jejuniChickens are a reservoir, common in companion animals who eat raw chicken
Diarrhoea that is watery, can last 15 days and also become chronic. May also contain blood and mucus
Also test for giardia (dogs) and toxoplasma (cats)
May cause immunosuppression - 101C. fetus fetusSheep
Causes abortion storms in late pregnancy
Oral transmission from pasture and water
Also from contact with the foetus, membranes and placenta
Can survive in the environment for 20 days - 102C. fetus and infertilityCan be C. fetus fetus or C. fetus veneralis
Bulls are the carriers and transmit via semen. Treat the bulls!!
Established infection is most common in bulls 3-4YO
Vagina of cows can become chronically infected over pregnancy and abort
Will clear infection if not pregnant - 103Affects on cow fertility from C fetus infectionEndometritis and late return to service
Further fertility issues from irregular cycling and a prolonged luteal phase
Most common in replacement heifers who are naive
Bulls appear normal clinically and produce normal semen - 104Diagnosis of Campylobacter foetusStrawberry lesions of the uterus, foetus and liver
Excessive fluid in the peritoneum and chest of the foetus on necropsy - 105Samples for diagnosis of campylobacterEnteritis - faeces
Abortion - placenta, foetal stomach contents, liver and lung
Infertility - semen, sheath lavage, vag mucus - 106Diagnostic tests for campylobacterGram stain (negative)
Fluorescent antibody test
Vag mucus agglutination - 107Campylobacter treatmentC. fetus: antibiotics for bulls only
C. jejuni: self limiting in humans but treat other animals - 108Campylobacter control (7)Avoid contaminated pasture
Reduce stock density
Remove aborted material
Segregate affected ewes
Hygiene to avoid transmission
Vaccination
Screen AI semen before use - 109Clostridium characteristicsGram positive
Obligate anaerobe
Spore forming
Drumstick shape
Normally in soil, putrefaction. Disease is not contagious! Opportunistic infection
Can be in GI tract - 110Groups of clostridium sp.Histotoxic: gas gangrene
Infection introduced to tissue, actively repliates and invades. Toxins produced. (Blackleg, malignant oedema, black disease).
Neurotoxic and enterotoxic
Endogenous infections, imbalance of commensal bacteria that are producing toxins: absorption via the GI tract causing illness. (Tetanus and botulinum). - 111TetanusTetanospasmin is the neurotoxin, released when bacteria lyse
Blocks inhibitory impulses and interferes with release of neurotransmitter release
Causes muscle spasms and seizures
"Sawhorse" presentation - 112Phase 1 of clinical diseaseConstricted pupils
Tight lips
erect ears
can't open jaw
Photosensitivity - 113Phase 2Same as phase 1 plus erect tail
Sawhorse stance
trouble swallowing
Stiff walking - 114Phase 3Same as phase 2 plus
Muscle tremors
Inability to walk
Seizures - 115Phase 4Bradycardia or tachycardia
Hypertension or hypotension
Respiratory arrest - 116Risk factors cor C.tetani infectionContamination of deep, penetrating wounds like after castration or tail docking
10-20 day incubation period (must be anaerobic - wound must heal first) - 117Treatment of C.tetaniDepends on stage
Administer antitoxin/antibodies to neutralise the toxins
Control muscle spasms
Large dose of antibiotics - non lysing e. doxycycline
Vaccinate for prevention! - 118C.botulinum characteristicsFoodborne but not zoonotic
Causes irreversible flaccid paralysis - 119Clinical presentation of botulism in cattleAcute: sudden death
Sub-acute: Stiff gait, rumen atony, ataxia, dropped head, sternal recumbency, lolling tongue and salivating - 120Clinical presentation of botulism in birdsTwisted necks and dropped heads
- 121Prevention of botulism infectionPrevent contamination of feed from dead birds or rodents
Immunise with type specific toxoid
Add nitrates to preserved food to prevent germination of spores - 122Clostridial histologic diseasesBlack leg: C. chauvoei
Malignant oedema: C. novyi and C sordelli
Black disease: C. novyi type B - 123Blackleg (C. Chauvoei)Acute infection causing gangrenous myositis
Spores are ingested then in macrophages via latent infection
Injury to muscle causes toxaemia and death - 124Malignant oedemaC.novyi, C.sordelli
Necrosis, thrombosis, bloody oedema and gas in connective tissue
Puncture wounds resulting in oedema within hours.
Pyrexia, inappetence, dullness, discolouration and coldness - 125Black diseaseC.nobyi type B, also associated with liver fluke as it causes an anaerobic environment
Causes necrotic hepatitis and toxaemia
Rapid onset with depression and reluctance to move, white/yellow lesions
Death within 48 hours - 126Enterotoxic clostridial diseaseC.perfringens: Pulpy kidney and gas gangrene
- 127Enterotoxaemia type DPulpy kidney: Overeating disease
C.perfringens normal in GI tract
Sudden change in feeds imbalances gut flora causing C.perfringens to grow uncontrolled, causing toxaemia - 128Presentation of enterotoxaemiaSudden death
Pericardial effusion
Gelatinous clots
Autolysis of kidneys
Haemorrhagic enteritis
Grain in rumen - 129Control of clostridial diseaseVaccination
Prophylactic antibiotics
Prevent contamination of wounds - 130Antibiotic mechanism of actions (5)1. Inhibition of cell wall synthesis in replicating bacteria (B lactams)
2. Disrupt cell membranes (Polymixins)
3. Inhibit protein synthesis (Streptomycin [30s], Erythromycin [50s], Tetracycline [30s]).
4. Inhibition of nucleic acid synthesis (Ciprofloxacin)
5.Inhibition of metabolism - sulfonamides - 131Causes for antibiotic resistanceRaised MIC compared to normal strain
MIC too high for clinical use
Expressing a resistance mechanism or gene - 132Intrinsic resistanceInherent property of the organism, such as a cell wall impermeable to the drug
- 133Acquired resistanceOccurs after exposure to the drug such as mutation in DNA or acquisition of foreign DNA
- 134Mechanisms of antibiotic resistance (6)1. Drug alteration or inactivation
2. Target site is insensitive
3. Decreased drug accumulation
4. Bypassing drug sensitive step
5. Overproduction of target
6. Absence of target metabolic pathway - 135Beta lactam resistanceAntibiotic inactivation
Bacteria hydrolyse the drug so it can't bind to the target - 136Tetracycline resistanceDecreased accumulation of drug via Enhanced efflux: porins
Target site insensitive due to protection proteins - 137Resistance in sulfonamidesBy-passing antibiotic sensitive step
Modified version of the enzyme binds antibiotic 1000x less well than the typical enzyme.
Overproduction of target: hyperproduction of enzyme to overcome drug effectiveness - 138Resistance to IsoniazidAbsence of metabolic pathway
Gene lacking to produce enzyme that activates the antibiotic. - 139Why is resistance an issue?Treatment failure
Repeated or prolonged courses needed
Use of broad spectrum drugs promotes resistance
Expensive
Cross infection resulting in superbugs
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- Infectious disease Flashcards on Bacteriology , created by Kelly Scott on 13/07/2020.
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- Kelly Scott
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