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114 terms

Microbiology Test 6

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major functions of the skin - 4
prevents excessive water loss, temperature regulation, involved in sensory phenomena, provides barrier against microbial invaders (prevents biological molecules)
microbes that live on the skin
YEAST: Malassezia; BACTERIA: Staphylococcus, Micrococcus, diptheroids
what makes normally harmless microbes that live on the skin produce disease
if they penetrate epidermis or if immune system is suppressed
folliculitis
infection of the hair follicle (pimple)
folliculitis on eyelid base
sty
what produces furuncles (boil)
folliculitis infection that has spread to surrounding tissues
what is a carbuncle
multiple furuncles that have grown together
what is the most common cause of folliculitis
staphylococcus in grapelike arrangements isolated from pus, blood, or other fluids
what are the two species of staphylococcus commonly found on skin
staphylococcus epidermidis, staphylococcus aureus
characteristics of staphylococcus - 3
bacteria that are facultatively anaerobic, Gram-positive cocci arranged in clusters
what are staphylococcus tolerant of
salt, desiccation, sebum, keratin
what does S. aureus production of beta-lactamase cause
resistance to penicillin
what are virulence factors of S. aureus
enzymes, antiphagocytic capsule, protein A, toxins
diseases caused by S. aureus - 8
skin disease - folliculitis, sty, furuncle, carbuncle; staphylococcal scalded skin syndrome; impetigo; staphylococcal toxic shock syndrome; bacteremia; endocarditis; pneumonia; food poisoning
what causes SSSS
one or two different staphylococcus aureus strains that secrete exfoliative toxins, which dissolve proteins that hold cell membranes together
what is characteristic of SSSS
epidermis peels off in sheets
what causes impetigo
80% S. aureus; 20% S. pyogenes
what is S. pyogenes often called
Group A Streptococcus
what causes all cases of Erysipelas
S. pyogenes
what is Erysipelas the result of
impetigo infections which have spread through the lymph nodes
who is most likely to get impetigo
children
who is most likely to have impetigo turn into erysipelas
elderly
what causes necrotizing fasciitis
S. pyogenes, which invade tissues through breaks in the skin and secrete Exotoxin A and streptolysin S
characteristics of necrotizing fasciitis
flulike symptoms, digestion of connective tissue around muscles, toxemia, and death
what causes acne
dead Propionibacterium acnes (normal microbiota) and/or S. aureus combined with living leukocytes
what is used to treat acne
doxycycline and benzoyl peroxide; accutane for severe acne
what is cat scratch disease caused by
Gram-negative Bartonella henselae
how is G(-) Bartonella henselae transmitted
by cat bites or scratches
what causes pseudomonas infection
pseudomonas aeruginosa
who is likely to get pseudomonas infection
burn victims (bacteria grow under the surface of the burn)
why is pseudomonas difficult to treat
P. aeuruginosa is resistant to multiple drugs and disinfectants, and it is widespread
what is Rocky Mtn. Spotted Fever (RMSF) caused by
Rickettsia rickettsii
who carries Rickettsia rickettsii
ticks
what does RMSF cause
petechiae hemorrhages and sometimes encephalitis
what causes cutaneous anthrax
bacillus anthracis that infects a cut in the skin
what is produced as a result of cutaneous anthrax
crusty ulcer on the skin called black sore-eschar
what are poxviruses that cause human disase
smallpox; orf (sheep and goat), cowpox, monkeypox - rarely cause disease in humans
what was first human disease to be eradicated
smallpox
what causes chickenpox
herpes virus (varicella-zoster virus - VZV)
characteristics of poxvirus
produce lesions that progress through stages and then dry to form crust and possibly scar; fever
stages of pox - 6
macules (flat), papules (raised), vesicles (fluid-filled), pustules or pox (pus filled), crust, scar
what is shingles
chickenpox virus (varicella-zoster virus) that has been latent and dormant for many years and then reactivated
what causes warts
papillomaviruses that spread via direct contact or fomites
what causes almost all cervical cancers
genital warts
what causes rubella
togaviridae: rubivirus
what is rubella also known as
German measles, rubeola, 3-day measles
what virus causes birth defects
rubella (German measles)
who are primary rubella patients
child, fetus
how bad is skin rash associated with rubella
mild
are Koplik's Spots present with rubella
no
what causes measles
paramyxoviridae: morbillivirus
primary measles patients
child
what is measles also called
rubeola and red measles
what are complications of measles - 3
pneumonia, encephalitis, subacute sclerosing panencephalitis
extent of skin rash associated with measles
extensive
are Koplik's Spots present with measles
yes
what causes erythema infectiosum
Parvoviridae: erythrovirus
what is Erythema infectiosum
respiratory disease that also manifests as a rash
what is Erythema infectiosum also called
fifth disease
what are mycoses
fungal diseases
what are superficial mycoses
mycoses that produce keritinase and dissolve keratin of the hair, nails and skin
what are cutaneous mycoses
mycoses that grow in the skin and manifest as cutaneous lesions, caused by dermatophytes
what are systemic mycoses
mycoses affecting numerous systems
what is piedra
superficial mycoses infection on hair shafts caused by Piedraia hortae (black piedra) and Trichosporon beigelii (white piedra)
what is pityriasis
skin infection caused by Malassezia furfur, which feeds on oil produced by the skin
what is rose gardner's disease (sporotrichosis)
subcutaneous infection usually limited to arms and legs, but can enter lymphatic system near the site of the primary lesion, giving rise to secondary lesions on the skin surface along the course of lymphatic vessels
what causes rose gardener's disease
Sporothrix schenckii, which resides in soil and is most commonly introduced in wounds by thorn pricks or wood splinters
what is rose gardner's disease that has entered lymphatic system
lymphocutaneous sporotrichosis
what are common dermatophytoses - 5
tinea pedis (athlete's foot); tinea cruris (jock itch); tinea unguium or onchomycosis(nail fungus); tinea corporis (ringworm); tinea capitis (scalp)
what type of environment is the CNS
axenic
axenic
free of normal microbiota
how do pathogens access the CNS - 4
breaks in bones and meninges, medical procedures, traveling in peripheral neurons to CNS, infecting and killing cells of meninges (meningitis)
what two ways does bacteria cause disease in nervous system
1. infect cells of nervous system; 2. bacteria growing elsewhere release toxins that affect neurons
what results from infected cells in nervous system
meningitis, leprosy
what are the two forms of meningitis
cranial (encephalitis), spinal
what are the bacteria that cause meningitis
streptococcus pneumoniae, neisseria meningitides, haemophilus influenzae, listeria monocytogene, streptococcus agalactiae
listeria monocytogen characteristics - 3
disease in fetuses, pregnant women, immunocompromised individuals; least common bacterial meningitis; transmitted by contaminated foods
streptococcus pneumoniae characteristics - 2
leading cause of adult bacterial meningitis, but present in throat of 75% of humans without causing harm
neisseria meningitidis (meningococcal meningitis) characteristics - 3
causes 100% mortality if left untreated; only bacterial meningitis that becomes epidemic; virulancy depends on capsule and fimbriae
causes most cases of newborn meningitis (acquired during birth)
streptococcus agalactiae
how are most species of bacterial meningitis transmitted
respiratory droplets
how is bacterial meningitis diagnosed
based on symptoms and culturing of bacteria from CSF from spinal tap
bacterial meningitis s/s - 6
RAPID, sudden high fever; severe meningeal inflammation - cranial meninges (headache, vomiting, pain) and spinal meninges (stiff neck, altered muscle control); infection of the brain (encephalitis) can result in behavioral changes, coma, death
medical name for leprosy
Hansen's disease
nonprogressive leprosy, in patients with strong immune response
tuberculoid leprosy
leprosy resulting in progressive tissue destruction, in patients without strong immune response
lepromatous leprosy
causative agent of leprosy
mycobacterium leprae
MOST deadly bacterial toxin
clostridum botulinum
what does clostridum botulinum manifest as - 3
foodborne, infant or wound botulism
what causes tetanus, and how
clostridum tetani, by releasing neurotoxin tetanospasmin, which blocks inhibitory neurotransmitters in CNS, resulting in severe muscular contractions
what is the most mild form of meningitis?
viral meningitis
what causes 90% of viral meningitis?
enterovirus
how is viral meningitis spread
respiratory droplets and feces
conditions of poliomyelitis(polio)
asymptomatic infections, minor polio, nonparalytic polio, paralytic polio
90% of polio cases
asymptomatic infections
least common type of polio
paralytic polio
postpolio syndrome
muscle deterioration that affects 80% of polio patients 30-40 years after initial illness
what causes polio
poliovirus
how is polio transmitted most often
drinking contaminated water
what are the only hosts for leprosy (Hansen's disease)
armadillos and humans
what two diseases of the nervous system are causted by protozoa
African sleeping sickness, primary amebic meningoencephalopathy
what causes African sleeping sickness, how?
Trypanosoma brucei, through bite of an infected Tsetse fly
what causes primary amebic meningoencephalopathy
protozoans Acanthamoeba and Naegleria
what is primary amebic meningoencephalopathy
rare, but usually fatal disease found in contact lens solution, dialysis units, swimming pools
how does an infant get infected with botulism
through inhalation or ingestion of C. bolulinum endospores, particularly in honey
where do bacteria due to infant botulism grow
intestines
first symptom of infant botulism
constipation
other signs and symptoms of infant botulism
muscle weakness (floppy baby syndrome) causes weak cry, poor feeding (weak suckling), loss of head control, respiratory distress; may also experience lethargy and descending paralysis
what causes arboviral encephalitis
blood sucking arthropods (mosquitos)
what is rabies
degenerating brain and spinal cord disease that is zoonotic
spongiform encephalopathies
caused by prion (infectious protein); includes scrapie, mad cow disease, Creutzfeldt Jacob disase
how is spongiform encepphalopathy contracted
eating meat from infected cattle
what causes trachoma (conjunctivitis, pink eye)
chlamydia trachomatis that multiplies in the conjunctiva
what does untreated trachoma cause
blindness