Microbiology Test 4

Epidemiology

Epidemiology

study of epidemics, distributions, causes of diseases in a population

Communicable Disease

transmitted from one host to another (measles, cold, flu)

Non-communicable disease

do not spread from host to host (CVD, cancer, COPD)

Attack Rate

percentage of people who become ill after exposure to an infectious agent

Incidence

new cases in a specific time period in a specific population

Prevalence

total new cases at any time or for a specific period in a given population (per 100k people)

Morbidity

illness rate, incidence of disease in a defined population

Mortality

overall death rate in a population

Case-fatality rate

percentage of population that dies from a specific disease

Endemic Disease

constantly present disease

Sporadic Disease

few cases from time to time

Outbreak

group of cases at a brief period of time

Epidemic

unusually large number of cases

Pandemic

when epidemic spreads world wide

Human vs Non Human Reservoirs

where pathogens live: animal, human, or environment

Portals of entry

where microbes gain access into host; mouth, nose, eyes, ears, reproductive tract, urinary tract, open wound

Portals of Exit

where microbes shed from; mouth, nose, anus, semen and vaginal secretions, reproductive tract, urinary tract

Vertical transmission

from woman to fetus or mother to infant during childbirth

Horizontal Transmission

all other types of transfer; person to person

Direct Transmission

direct contact, droplet transmission

Indirect Transmission

airborne, vehicle borne, vector borne

Virulence

those with more virulence factors spread more extensively

Infectious Dose

minimum number of pathogens required

Incubation Period

Long incubation period allows extensive spread

Selective Toxicity

cause greater harm to microbes than you, expressed at therapeutic index (lowest toxic dose/ dose youse for therapy)

Bacteriostatic

antimicrobial action; inhibits bacterial growth, relies on patient’s immune system to eliminate

Bactericidal

antimicrobial action; kills bacteria, sometimes only inhibitory

Broad Spectruma

affect a wide range, life- threatening illness (eliminates normal microflora too)

Narrow Spectrum

affect limited range, requires identification of pathogen and sensitivity testing

Antagonistic

effect of combination; interferes with each other

Synergistic

effect of combination; one enhances the other

Additive

effect of combination; neither antagonistic or synergistic

Intrinsic (innate) Response

ex: Mycoplasma species lack cell wall, making them resistant to penicillin and other drugs attacking cell wall

Acquired Resistance

spontaneous mutation and horizontal gene transfer

Antibacterial Medications target specific process and structures; such as…

cell wall synthesis, protein synthesis, nucleic acid synthesis, metabolic pathways, cell membranes

Mechanisms Inhibiting Cell Wall Synthesis

blocks formation of peptidoglycan in cell wall

Inhibiting Protein Synthesis

knows difference between prokaryote and eukaryote

Aminoglycosides

Mechanism Inhibiting Protein Synthesis; bind to 30S; blocking initiation of translation, used with B-Lactam

treat: Streptomycin, Gentamycin, Tobramycin

Tetrocyclines and Glycylcyclines

Mechanism Inhibiting Protein Synthesis; bind to 30S, used for gram positive and negative

Macrolides

bind to 50S, alternative to penicillin, prevent continuation of translation

Treats: erythromycin, clarithromycin, and azithromycin

Chloramphenicol

prevent peptide bond; wide spectrum, last resort, aplastic anemia

B- Lactam antibiotics

Penicillin, Cephalosporins - Gram Negative

Glycopeptide Antibiotics

vancomycin - Gram Positive

Bacitracin

topical, interferes with transport of PG precursors

Flouroquinolones

Blocks nucleic acid synthesis; inhibits topoisomerases (enzyme group that maintains DNA supercoiling), wide spectrum

Rifamycin

Blocks nucleic acid synthesis; inhibits bacterial RNA polymerase, prevents initiation of transcription, Gram Positive and Mycobacterium

Interfere with Metabolic Pathway

Folate Inhibitors and Sulfonamides/ Tremethoprim (inhibit steps in folate biosynthesis)

Daptomycin

interfere with cell membrane integrity; Gram positive

Polymyxin B

interfere with cell membrane integrity; gram negative, topical application

Effective against Mycobacterium Tuberculosis

waxy cell wall → prevent entry, 4 for 8, 2 for 18

Isoniazid (INH) = inhibits mycolic acid synthesis

Ethambutol = inhibits enzymes required to synthesis of other cell wall components

Pyrazinamide = blocks restart of stalled ribosomes

More toxic second line and less effective

Kirby - Bauer Disc Diffusion Test

bacteria on agar, drug diffuses outward, “zone of inhibition”

Antiviral Medications

Target: polymerase, specific to one virus

Ex: Amantadine and Rimantadine → Flu, prevent uncoating

Acyclovir and Ganciclovir → interfere with Nucleic Acid Synthesis

Entry Inhibitors and Protease Inhibitors → HIV and Hep C

Antifungal Medications

Difficult bc eukaryotic

Target: ergosterol → interfere with plasma membrane synthesis and fxn

ex: Polyenes → produced by streptomyces, toxic, systemic use

Azoles and Allylamines

Antiprotozoan and Antihelminitc Medication

interfere with biosynthetic pathwars, little research and development

Upper Respiratory Tract

lined by mucous membranes, lined with ciliated epithelium lines, mucociliary escalator

Nose and Nasal Cavity : warm, staphylococcus Aureus

Pharynx and Epiglottis

Eyes : conjunctiva

Ears : external, middle (sterile) and inner

Lower Respiratory Tract

usually sterile, larynx, trachea, bronchi, and lungs

Streptococcal Pharyngitis → “Strep Throat”

s/s : sore throat, difficulty swallowing, fever, patches of pus in throat, abdominal pain and headache

incubation : 2-5 days, recover after 1 wk

Causative Agent : Streptococcus pyogenes → antibiotic treatment

Diphtheria

s/s : sore throat, slight fever, extreme fatigue, swelling of neck, pseudomembrane (dead cells) on tonsil and throat

incubation : 2-6 days

causative agent : Corynebacterium diphtheriae → releases toxin which does the damage = antiserum + antibiotic

Pinkeye, Earache, and Sinus Infection

common, occur together w/ same causative agent : Haemophilus influenzae or Streptcoccus pneumoniae

conjunctivitis : tears, redness swollen eyelids, sensitivity to bright light, pus

Otitis Media : severe earache and pain from fluid and pus collection behind eardrum, preceded by infection of nasal chamber and nasopharynx

Sinusitis : facial pain, pressure, headache, nasal discharge

Uses antibiotics

Common Cold

s/s : sore throat, runny nose, cough, sneezing, runny nose, cough

incubation: 1-2 days, gone w/in wk

causative agent : rhinovirus, picornavirus family

Adenoviral Respiratory Tract Infection

s/s : runny nose, fever sore throat, gray/ white pus on pharynx and tonsils, severe cough and chest pain, conjunctivitis, diarrhea

causative agent : adenovirus → infectious long time, 1-3 wk recovery

Pneumococcal Pneumonia

s/s : runny nose (1-2 days), cough, fever, chest pain, sputum production, sudden temperature rise, intense chill

Causative agent : Streptococcus pneumoniae

treatment: penicillin and erythromycin, vaccine

Klebsiella Pneumonia

Signs and symptoms: similar to pneumococcal pneumonia,thick and bloody gelatinoussputum

Incubation time : 1-3 days

Causative agent : Klebsiellapneumoniae, causes lung abscesses

Treatment : antibiotics (if susceptible),surgery to drain abscesses

Mycoplasmal Pneumonia → “Walking Pneumonia”

Signs and symptoms: fever, headache, muscle pain, fatigue(gradual onset), dry cough

Incubation time 2–3 weeks

Causative agent: Mycoplasma pneumoniae (no cell wall)

Treatment:antibiotics (can shorten illness if given early)

Pertussis → “Whooping Cough”

s/s: 3 stages (1-2 wk incubation); 1. Catarrhal Stage (inflammation of mucous membranes) = like upper respiratory infection, most infectious; 2. Paroxysmal Stage (repeated sudden attacks) = sudden bursts of violent coughing; 3. Convalescent Stage = not contagious, coughing decrease

causative agent : Bordetella pertussis → releases toxin

treatment : antibiotics and vaccine

Tuberculosis (TB)

s/s : fever, weight loss, night sweating, persistent cough w/ bloody sputum

causative agent : mycobacterium tuberculosis

treatment : multiple drugs over long period of time

• granuloma (localized collection of inflammatory cells)

• Latent TB vs Active TB

Legionnaires’ Disease

s/s : headache, muscle ache, high fever, confusion, shaking chills, dry cough with sputum, GI tract symptoms

incubation : 2-10 days

causative agent : Legionella pneumophila - found in water systems and biofilms

treatment : antibiotics and oxygen therapy

• relatively new

Influenza

s/s : headache, fever, sore throat, muscle pain (abt 1 wk)

incubation time : 2 days

Causative Agent : influenza virus A, B, C, D, many different types of differentiation w/ antigenic drift and antigenic shift

Respiratory Syncytial Virus Infection

s/s : runny nose, cough, wheezing, difficulty breathing, croup

incubation : 1-4 days

Causative agent : respiratory syncytial virus (RSV), causes cells to clump together, die, and clog bronchioles

• heavily affects infants and young children

Hantavirus Pulmonary Syndrome

s/s : fever, muscle aches, nausea, vomiting, diarrhea, severe SOB and death within few days

incubation : 3 days to 6 wks

causative agent : hanta virus, infected rodents - inhalation of dust contaminated w/ urine, feces or saliva

no effective treatment

• Found in “Four Corners” region - AZ, CO, NM, UT

Coccidiodomycosis (Valley Fever)

causitive agent : Coccidioides Immitis (dimorphic fungus), exposure to dust and soil

s/s : flu like, joint paint, painful nodules

not worrisome for healthy people

Histoplasmosis (Spelunker’s Disease)

causitive agent : histoplasma capsulatum (dimorphic fungus), grows in soil or bat and bird droppings, high risk for cave explorers

s/s : fever, cough, chest pain, SOB, mouth sores

Pneumocystis Pneumonia (PCP)

causative agent : penumocystis jiroveci, attach to alveolar walls and fill them with fluid

s/s : SOB, low fever, discoloration

• common opportunistic infection for AIDS patients

• latent in healthy people

SKIN

3 layers (epidermis, dermis, subcutaneous tissue), normal microbiota (diptheroids, staphylococci, and fungi), route of invasion : strands of hair

Acne Vulgaris

s/s : increased sebum secretion, thickening of hair follicle epithelium, blockage produce black and whiteheads

causative agent: propionibacterium acnes

• inflammatory response damages follicle wall yielding an abscess

• typically arises at puberty bc rise in sex hormones

Hair Follicle Infection

3 outcomes:

1. folliculitis = inflammation, red bumps

2. Furuncle = redness, swelling, tenderness, pain

3. Carbuncle = large area of redness, swelling, pain, pus, fever

Causative Agent : staphylococcus aureus

treatment : minor surgery to drain

Staphylococcal Scalded Skin Syndrome

s/s : redness, fever, wrinkled skin, large blisters

causative agent : staphylococcus aureus ( toxin releases causing skin to split and peel)

Treatment : antibiotic

Streptococcal and Staphylococcal Impetigo

s/s : superficial inflammation, thin walled blisters, yellowish crust, little fever, enlargement of nearby lymph nodes

causative agent : streptococcus pyogenes and staphylococcus aureus

treatment : antibiotics and antiseptics

• pyoderma : superficial skin infection causing pus production

Rocky Mountain Spotted Fever (RMSF)

s/s : headache, muscle and join pain, fever, rash on palms, wrist, ankles and soles

causative agent : rickettsia ricketsii, transmitted via tick → inflammation response causes clotting in vessels

treatment : antibiotic

Lyme Disease

3 Stages

1. Early localized infection = erythema migrans (bullseye), flu like symptoms

2. Early Disseminated Infection = altered nervous system, face paralysis and headache

3. Late Persistent Infection = chronic nervous system impairment, joint pain

Causative Agent: borrelia burgorferi

treatment : antibiotics

Varicella (Chickenpox)

s/s : mostly mild, small red spots, progresses to little bumps and blisters, itchy lesions

causative agent : Varicella Zoster Virus

incubation : 2 weeks

Reactivation : Shingles

Treatment : antivirals and vaccine

Rubeola (measles)

s/s : fever, runny nose, swollen and red eyes, fine rash

causative agent : rubeola virus, respiratory route → suppressing immunity

treatment : no antiviral, vaccine

• many secondary infections including Subacute Sclerosing Panecencephalitis ( SSPE)

Rubella (German Measles)

s/s : slight fever, mild cold symptoms, faint rash, painful joints

causative agent : rubella virus

treatment : no treatment, vaccine

• Congenital Rubella Syndrom (CRS) : damages developing fetus

Warts

small tumors (papillomas), causative agent : papillomavirus, infect via abrasions, treat via killing/ removing

Superficial Cutaneous Mycoses

ex: Jock itch, athlete’s foot, ringworm

s/s : usually none, sometimes itching, odor, rash, scaly area w/ redness, nail seperating from skin

causative agent : dermatophytes → produces keritinase

Melassezia Furfur

generally harmless, scaly rash, dandruff

Candida Albicans

in normal microbiota, invading deep laters of skin and tissue, diaper rash

Wound

exposed normally protected tissue

Wound healing

1. blood clot

2. formation of granulation tissue

3. regrowth of blood vessels

4. formation of scar tissue

5. regeneration of epithelium

Abscess

localized pus surrounded by inflamed tissue, formed as a result of body’s defense

• must burst/ drain to heal

Pus

thick, yellowish fluid, living and dead leukocytes, tissue debris, and proteins which localize infection

Staphylococcal Wound Infection

s/s : production of pus, swelling, redness, pain

causative agent : staphylococcus species

• staphylococcus aureus = inflammatory reaction, Toxic Shock Syndrome, Systemic Abscesses

• Staphylococcus epidermidis = minor abscesses around stitches and colonize on medical devices

treatment : clean wounds from surgery, problematic bc MRSA

Flesh Eating Disease

s/s : severe pain at wound site, skin discoloration, fever, confusion

causative agent : streptococcus pyogenes → produces endotoxins that destroy)

treatment : immediate surgery to remove dead tissue, broad spectrum antibiotics

• generally easy to treats

• risks : diabetes, cancer, alcohol, cancer, surgery

Pseudomonas Aeruginosa

s/s : chills, fever, skin lesions, shock, green colored pus

Causative agent : Pseudomonas aeruginosa

treatment : only few antimicrobials, established infections are difficult, remove dead tissue

Tetanus (Lockjaw)

s/s : painful and uncontrollable muscle spasms, difficulty swallowing, difficulty breathing, abnormal heart rate rhythms

causative agent : Clostridium Tetani → releases tetanospasmin (exotoxin)

treatment : passive immunity and muscle relaxants

Clostridial Myonecrosis (gas gangrene)

s/s : severe pain, brownish fluid leaking form would, overlying skin stretched and turned black, delirium

causative agent : clostridium perfringens → releases a-toxin

treatment : prompt removal of tissue, antibiotics

Actinomycosis (Lumpy Jaw)

s/s : painful swelling under skin (burst, drain pus, heal and reappear) on jaw or neck

causative agent : actinomyces israelli

treatment : antibacterial medication over period of time

Human Bite Wound

s/s : wound that becomes painful, swells, leaks pus

causative agent : steptococci, fusiforms, sprichetes, staphylococcus aureus

treatment : antibaterial and cleaning

Pasteurella multocida bite wound (animal)

s/s : spreading redness, tenderness, tissue swelling, pus discharge, abscesses

causative agent : pasteurella multocida, carried by animals (cats)

treatment : antibacterial

Sporotichosis (Rose Gardeners Disease)

s/s : chronic ulcer at wound, enlargement of lymph nodes, red lesions that bleed easily, no pus

causative agent : Sporothrix Schenickii (dimorphic fungus)

Treatment : itra conazole and amphotericin B