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Concept Dis. Ch 6

Pathogenic Microorganisms

Lyme disease is caused by a bacterium of what shape? spiral
is an example of an acid-fast organism tuberculosis
enzyme that antibiotic-resistant bacteria produce to inactivate penicillin Penicillinase
hypersensitivity to antibiotics can produce fatal reaction in some patients
Rickettsiae and Ehrlichieae are transferred to humans through insects
mycoplasmas cause primary atypical pneumonia
most fungal infections occur after disruption of the natural bacterial flora of the body
host a number of animal parasites capable of causing illness/disability human body
shape, Gram-stain reaction, biochemical/cultural characteristics & antigenic structure four major factors used to classify bacteria
coccus spherical bacterium
bacillus rod shaped bacterium
staphylococci cocci bacterium growing in clusters
diplococci cocci bacterium growing in pairs
streptococci cocci bacterium growing in chains
staining procedure where bacteria stained w/crystal violet, treated w/strong iodine solution, decolorized w/ethanol/ethanol-acetone, & counterstained w/contrasting dye Gram-stain method
gram-positive those retaining the stain during Gram-stain method
gram-negative those losing the stain but staining with the counterstain
aerobic organisms grow best in presence of oxygen
anaerobic organisms grow only in absence of oxygen, or extremely low oxygen tension
some bacteria grow well under aerobic/anaerobic conditions
flagellum whip-like process that propels organism/sperm
organisms that lake flagella are non-motile
spores highly resistant spherical structure produced by some bacteria to assure survival under adverse conditions
extremely resistant bacterial modification that forms under adverse conditions may be considered dormant
contains large #s of antigens associated w/cell body, capsule & flagella (if motile) each type of bacterium
defining system of antigens unique for each group of bacteria antigenic structure
found in gastrointestinal tract & capable of causing a typhoid-like febrile illness Salmonella
gram-positive cocci staphylococci, streptococci, pneumococci
gram-negative cocci gonococci, meningococci
gram-positive bacilli corynebacteria, Listeria, bacilli, clostridia
gram-negative bacilli hemophilus, Gardnerella, Francisella, yersinia, brucella, legionella, salmonella, shigella, campylobacter, cholera bacillus, colon bacillus (Escherichia coli)
gram-positive spiral organisms treponema pallidum, Borrelia burgdorferi
gram-positive acid-fact organisms tubercle bacillus, leprosy bacillus
normal inhabitants of skin & nasal cavity staphylococci
pathogenic/non-pathogenic staphylococci can be distinguished by appearance of colonies on media containing blood
produce zones of hemolysis around growing colonies pathogenic staphylococci
do not hemolyze red cells non-pathogenic staphylococci
pathogenic staphylococci are common causes of boils, other skin infections & post-op wound infections
pose serious problem in hospitals were organisms are widely distributed & patients susceptible to infection staphylococci infections
streptococci are classified on the basis of their serological group & type of hemolysis produced when grown on solid medium containing blood
Lancefield system classification of hemolytic streptococci into groups on basis of serologic action
20 major groups are based on differences in carbohydrate antigens present in cell walls Lancefield system
Lancefield system groups are designated A through H & K through V
streptococci groups of most medical importance A, B & D
Lancefield system classification is based on alpha hemolysis, beta hemolysis or no hemolysis on blood agar platelets
produce green discoloration of blood immediately around colony alpha hemolytic/alpha streptococci
alpha streptococci named because of its growth characteristic Streptococcus viridans
alpha streptococci are inhabitants of throat & mouth
alpha streptococci cannot be classified by Lancefield system because lack carbohydrate antigen possessed by other streptococci
produce narrow zone of complete hemolysis around growing colony beta hemolytic/beta streptococci
one of most important beta streptococci in Lancefield group group A /group A beta streptococci
group A beta streptococci are extremely pathogenic, cause streptococcal sore throat, scarlet fever, serious skin infections & intrauterine infection after birth
infection with the group A type of hemolytic streptococci "fleshing eating bacteria" necrotizing fasciitis
may cause serious urinary tract & wound infections, & serious infections in newborns group B beta streptococci
closely related to group D streptococci, classified separately, inhabit intestinal tract enterococci
enterococci are resistant to multiple antibiotics
grow in pairs & short chains, common cause of bacterial pneumonia Streptococcus pneumoniae - pneumococci
most gram-negative cocci, which inhabit the upper respiratory path, are nonpathogenic & members of genus Neisseria
Neisseria meningitidis cause of type of meningitis that occurs in epidemics
Neisseria gonorrhoeae causes STD gonorrhea
Corynebacteria & Listeria two important groups of gram positive bacilli, non-spore-forming aerobic bacteria
member of aerobic spore-forming gram-positive organisms, which is highly pathogenic Bacillus anthracis, causes anthrax
inhalation of anthrax spores from contaminated wool, yarn, or animal products allows for spores germinate within pulmonary alveoli, actively proliferate & produce lethal toxins causing tissue destruction
anthrax spores are ingested by macrophages & transported to regional lymph nodes continuing germination & toxin production
antibiotics effective against germinated form of anthrax are not effective against spore of organism
prolonged course of antibiotics are needed for exposure to inhaled anthrax because spores transported to lymph nodes may continue to germinate up to 2 months
anaerobic spore-forming bacilli are called Clostridia
Clostridia inhabit intestinal tract of humans/animals & found in soil
Clostridia in known to cause gas gangrene, tetanus & botulism
caused by Clostridia perfringens & related organisms, developing in dirty, spore-contaminated wounds gas gangrene
Clostridia produce large amounts of gas by fermenting in necrotic tissue
Clostridia also release powerful toxins that destroy tissues & cause widespread systemic effects
Clostridia tetani, tetanus, produces potent toxin causing spasm of voluntary muscles
"lockjaw" comes from marked rigidity of jaw muscles that is common feature of tetanus
botulism is "food poisoning" caused by ingestion of neurotoxin produced by anaerobic spore forming bacillus Clostridium botulinum growing improperly in canned/preserved food
antibiotic-associated colitis intestinal infection caused by Clostridium difficile
meningitis in infants/young children & respiratory infections in patients with chronic lung disease Hemophilus influenzae
one member of Yersinia is responsible for bubonic plague
Legionella causes serious respiratory illness Legionnaires disease
gram-negative bacteria that cause febrile illness & gastroenteritis Salmonella, Shigella, Campylobacter, & cholera bacillus
Helicobacter causes chronic inflammation of stomach lining & stomach ulcers
best know enteric bacterium colon bacillus Escherichia coli
Treponema pallidum is spiral organism causing syphilis
Borrelia burgdorferi is spiral organism causing Lyme disease
tick-borne systemic infection characterized by neurologic, joint, & cardiac manifestations Lyme Disease
waxy capsule stained by difficult means of certain red dyes acid-fast bacteria
substance that destroy bacteria or inhibit growth antibiotic
antibiotics are useful clinically because of ability to injure bacterial cells without significant injury to patient
bacterial genetic material is arranged as circular DNA molecule attached to cell membrane
some bacteria contain plasmids which have gene coding useful to bacteria & harmful to people because resistance to antibiotics, toxin production, formation soluble factors to inhibit normal bacterial floral
deficient in certain enzymes & can live only as parasites inside of cells of infected individual nonmotile bacteria
spherical, densely staining structures; masses of virus/products of virus multiplication inclusion bodies
inclusion bodies spherical structures in nucleus/cytoplasm of virus-infected cells
small, gram-negative, nonmotile bacteria; inhibited by sulfonamide drugs chlamydiae
small intracellular bacteria that can only multiply within cells of infected person Rickettsiae
Rickettsiae is transmitted to human by insect bites
Rickettsiae multiply in endothelial cells of small blood vessels
Rickettsiae can lead to thrombosis, rupture & necrosis
rickettsial infections usually causes a febrile illness, associate w/skin rash
Typhus & Rocky Mt Spotted Fever are the most common rickettsial infections
organisms transmitted by ticks, which infect WBC are called Ehrlichieae
when Ehrlichieae infects WBCs they contain compact clusters of organisms called morulae
morulae are able to be identified with blood smear tests
febrile illness, similar to rickettsiae, & may be associated w/skin rash ehrlichiosis
rickettsial infections respond to tetracyclines & chloramphenicol antibiotics
ehrlichiosis infections respond to tetracycline antibiotic
very small & fragile bacteria, lacking a cell wall mycoplasmas
mycoplasmas respond to the antibiotics tetracycline & erythromycin
small infectious agents are viruses
protein covering central nucleic acid core of a virus capsid
one of the subunits that make up the capsid of a virus capsomere
capsomeres are arranged are the genome in precise geometric fashion
nucleic acid of virus genome can be arrange in single/double strand
viruses have few metabolic enzymes so they must rely on cells of infected person to carry out their activities
classification based on portion of body/organ system in which viral infection produced most prominent clinical manifestations older classification of viruses
classification based on nucleic structure, size, structural configuration & biological characteristics modern classification of viruses
condition in which virus infects cell w/out causing evidence of cell injury latent viral infection
more virulent viruses which regularly cause cell injury, manifested by necrosis & degeneration of infected cell cytopathogenic effect
some viruses with a cytopathogenic effect induce cell hyperplasia & proliferation rather than cell necrosis
under certain circumstances, latent symptomatic viral infections may become activated leading to actual disease
member of herpes group, which causes chicken-pox & shingles varicella-zoster virus
after the initial infection w/varicella-zoster virus, it remains dormant in the sensory nerve ganglia
characteristic band-like vesicular skin rash in segment of upper skin supplied by sensory nerve, along the course of a spinal nerve shingles
inclusion bodies aide in diagnosis by recognizing viral infection/type of viral disease present
group carbohydrate-containing proteins produced by cells in response to viral infection & able to interfere w/viral multiplication interferon
immunity associated w/formation of antibodies produced by plasma cells humoral immunity
defense against foreign antigens provided by population of T lymphocytes that can attach/destroy foreign antigens cell-mediated immunity
primary sources of interferon monocytes & lymphocytes
filamentous branching structures formed by fungi hyphae
matted mass of hyphae forming fluffy colony characteristic of fungi mycelium
plantlike organisms w/out chlorophyll fungi
two subdivisions of fungi yeasts & molds
small ovoid/spherical cells that reproduce by budding yeasts
form large colonies composed of hyphae molds
disturbance in normal bacterial flora & impaired immunological functions predispose person's to systemic fungal infection
cancer patients treated w/cytotoxic drugs may develop systemic fungal infections
group of fungi that cause superficial infections of skin; symptoms include itchy, scaling skin lesions on scalp & other body parts dermatophytes
superficial fungal infection of mucous membranes caused by yeast-like fungus Candida infection
fungi can be identified by biopsy or culture of infected tissue
fungal infection causing acute, self-limited respiratory infection due to inhalation of spores histoplasmosis
fungal infection usually manifests as an acute pulmonary infection due to inhalation of spores; can lead to chronic/severe progressive systemic disease coccidiomycosis
less common fungal infection due to inhalation of spores from Cryptococcus neoformans, which causes cryptococcosis blastomycosis
yeast-like organism w/large mucoid capsule; initially pulmonary infection but if transported to blood stream & meninges of brain causing chronic meningitis Cryptococcus neoformans
Cryptococcus neoformans can be identified in smears/cultures of spinal fluid
chronic/progressive systemic fungal infections are treated with various antifungal antibiotics
can follow the use of broad-spectrum antibiotics anti-biotic associated colitis
Impaired immunity, antibiotic-related change of normal bacterial flora, drugs that impair functions of the immune system, & chronic diseases in which immunity is impaired factors rendering patient susceptible to infection by fungus of low pathogenicity