Biology of Disease Exam 3

opportunistic infection

infection by an organism that would not be pathogenic in someone with a normal immune system

prion

abnormal forms of host protein normally found in neurons; undergoes a conformational change with resistance to proteases which promotes conversion of normal to abnormal proteins; spread through instruments, organ donation, autopsy, surgery, or blood transfusion

virus

intracellular parasite that depends on host energy/cell organelles for replication

gram positive

bacteria with thick wall that retains crystal violet

gram negative

bacteria with thin cell wall

mycoplasma

bacteria with no cell wall

parasite

sexual (host) and asexual reproduction (vector)

fungi

thick cell walls (chitin); yeast, hyphae, or both

protozoa

single cell eukaryocytes

ectoparasites

insects or arachnids that attach to skin

physical, microbiological, chemical and immunologic

host barriers to infection

skin, respiratory tract, urinary tract, gastrointestinal tract, trauma

portals of entry

mucociliary action, phagocytosis by lung macrophages

respiratory tract defenses

mucociliary action

lung disease, tobacco smoke, and virulent bacteria and viruses inhibit

mycobacteria

inhibit phagocytosis by lung macrophages

urinary flow, normal vaginal bacteria

urogenital tract defenses

indiscriminate antibiotic therapy

inhibits normal vaginal bacteria inhibiting pathogen growth

chemical, immunologic, microbiologic

gastrointestinal tract defenses

gastric acid, bile salts, pancreatic enzymes

chemical gastrointestinal tract defenses

IgA

immunoglobulin secreted by intestinal mucosa

local, lymphatic, hematogenous, peritoneal, neural

spread of infectious organisms

local

spread of streptococcal cellulitis and staphylococcal abscesses

neural

spread of rabies, varicella-zoster, herpes

fecal-oral

transmission of hepatitis A, vibrio cholerae

respiratory

transmission of tuberculosis, legionella

bloodborne

transmission of hepatitis B and C, HIV

sexual

transmission of neisseria gonorrheae, chlamydia

vector

transmission of malaria, typhus

zoonotic

transmission of trichinella, rabies

viruses

smallest of all microorganisms

viruses

obligate intracellular parasites

outer protein coat, inner nucleic acid (DNA or RNA)

virus structure

margination, multinucleation, molding

3Ms of herpes

bacteriophages, plasmids, transposons

virus-like nucleic acid particles that invade bacteria and increase virulence

toxin production, antibiotic resistance

bacteriophages, plasmids, and transposons increase bacterial virulence by enabling

prions

infective protein particles

prions

only infectious agents that do not contain nucleic acid

prions (CNS degenerative diseases)

creutzfeldt-jakob disease, bovine spongioform encephalopathy

bacteria

smallest, simplest organisms that are capable of independent existence

prokaryotic

bacteria with cell envelope, no nucleus, 0.1-10 microns, universally susceptible to antibiotics

chlamydiae, rickettsiae, mycoplasma

infectious organisms that have some properties of bacteria but lack others, smaller than other bacteria (<1 micron)

pyogenic cocci

staphylococcus, streptococcus, pneumococcus, neisseria meningitidis, n. gonorrhoeae

pyogenic cocci

bacteria that produce pneumonia, cellulitis, abscesses, pharyngitis, meningitis, gonorrhea/PID

pyogenic cocci

treated with penicillins, cephalosporins, erythromycin, vancomycin, quinolones, surgical drainage of abscesses

gram negative bacteria

escherichia coli, klebsiella, enterobacter, pseudomonas

gram negative bacteria

cause pneumonia, septicemia, wound infection, abscesses, urinary tract infection

gram negative bacteria

treated with cephalosporins, quinolones, TMP/SMX, aminoglycosides, antibiotic susceptibility testing

pseudomonas

treated with piperacillin, aminoglycosides, quinolones

hemophilus influenzae

most common pediatric infection

hemophilus influenzae

causes meningitis, pharyngitis, pneumonia

hemophilus influenzae

treated with cephalosporins, TMP/SMX, macrolides

enteric infections

salmonella spp., shigella, enteropathogenic e. coli, helicobacter, vibrio cholerae

enteric infections

cause enterocolitis, gastritis

enteric infections

treated with symptomatic support (hydration, electrolytes), cephalosporins, quinolones

macrolides

helicobacter treatment

obligate anaerobes

what type of bacteria are clostridium spp.

clostridial infections

cause tetanus, botulism, gas gangrene (c. perfringens), antibiotic-associated colitis (c. difficile)

clostridial infections

treated with toxoids, penicillin, clindamycin, debridement (c. perfringens), metronidazole, d/c offending antibiotic (c. difficile)

chlamydia

genital infections, conjunctivitis, pneumonia

chlamydia

treated with azithromycin, tetracyclines

rickettsia

rocky mountain spotted fever, typhus

rickettsia

treated with doxycycline, rifampin, quinolones

mycoplasma

atypical pneumonia

erythromycin

mycoplasma treatment

mycobacteria

tuberculosis, leprosy

tuberculosis

lung disease characterized by caseating granulomas, offten affects other organs

tuberculosis

treated with isoniazid, rifampin, pyrazinamide

atypical mycobacteria

M. avium/intracellulare (MAI), M. kansasii, lung, lymph node, skin infections, disseminated infection in HIV patients

leprosy

treated with dapsone, rifampin

fungi

eukaryotic organisms capable of sexual reproduction, larger than bacteria (2-200 microns)

yeast

fungi with rounded, budding structures

hyphae

fungi with filamentous, branching structures

candida

vaginitis, oral thrush, pneumonia, normal flora in mouth and vagina

dermatophytes

skin and nail infections (“athlete’s foot”, tinea)

aspergillus

allergic bronchitis, pneumonia in immunocompromised patients

histoplasma, coccidioides

pulmonary granulomatous disease

cryptococcus

meningitis, pneumonia, usually in immunocompromised patients

pneumocystis

pneumonia in HIV patients

imidazoles/triazoles

ketoconazole, itraconazole, fluconazole, topical preparations for dermatophytosis/candida vaginitis, oral tablets/suspensions for esophagitis/granulomatous diseases, parenteral for some deep infections

nystatin

topical or oral treatment of candidiasis

amphotericin B

disseminated fungal infection treatment

pneumocystis

treated with TMP/SMX, pentamidine

parasites

animal or animal-like disease-causing organisms

protozoa, helminths, ectoparasites

three categories of parasites

protozoa

single-celled, usually motile parasites; blood, lymph node, and mucosal surface infections

protozoan intestinal infection

giardia lamblia

protozoan vaginitis

trichomonas vaginalis

malaria

plasmodium Sp.

protozoan intestinal/liver infections, eye infections, meningitis

entameba, acanthameba, naegleria

protozoan sleeping sickness

trypanosoma sp.

helminths

roundworms, flatworms, tapeworms, flukes

pinworm

intestinal/anal helminth

strongyloides

large intestinal roundworm

tapeworms

intestinal parasites

schistosomes

blood flukes, ova seen in intestine or urinary bladder

ectoparasites

arthropod parasites that attack to skin, often serve as vector for viral or bacterial disease

ectoparasites

fleas, lice, ticks, mites

scabies

ectoparasite example

most viruses, some bacteria

infect through direct invasion and injury of cells

many bacteria

infect through release of toxins and enzymes