Microbiology Flashcards
Main locations containing anaerobes
skin, oral cavity, gut, female genital tract
Claustridia spp lead to these types of diseases
Botulism, tetanus, gas gangrene, invasive skin infections, food poisoning, pseudomembranous colitis
Key characteristics of Clostridia spp (gram?, aero/anaero, etc)
Anaerobic, gram +, spore-forming rods
Type of Clostridia that is the most common cause of invasive infections?
C. perfringens
Clostridia virulence factor, what does it do?
Lecithinase- phospholipase that kills cells and hemolyzes RBCs –> muscle necrosis
Actinomyces key characteristics
Anaerobic, non-spore forming, gram + rods
Propionibacterium key characteristics
Anaerobic, non-spore forming, gram + rods
Gross and microscopic appearance of Actinomyces
Colony - molar appearance
G+ rods form chains
In abscesses, form “sulfur granules”
Where and when do actinomyces infections typically occur?
Lumpy Jaw!
Chronic suppurative and granulomatous infections of the cervico-facial area. Usually associated w/ poor oral hygiene or invasive dental surgery)
Most common cause of acne
Propionibacterium
Key characteristics of Baceroides
Anaerobic, gram (-), non-spore forming rods, catalase +, SOD +, can grow in bile, and beta-lactamase +
Bacteroides has a _________ that makes it anti-phagocytic.
Polysaccharide capsule
Keys in lab Dx of Bacteroides (resistance, plating, etc).
Makes beta-lactamases, can grow in bile
Manifestations of cat bites vs dog bites
Cats: hands/upper extremities, deep abscess/osteomyelitis
Dogs: depressed/open skull fx, severe scalp and intracranial bleeding
Capnocytophaga canimorsus
Normal flora in dogs and cats
Can cause myocarditis, endocarditis, meningitis
Resistant to TMX/SMX and aminoglycosides
Pasteurella multocida
Nasopharynx of cats
Causes local cellulitis, low-grade fever
Sensitive to beta-lactams, azithromycin
Avoid erythromycin, clindamycin
Oral drug of choice in dog/cat bites
Amoxicillin-clavulanate
IV drug of choice in dog/cat bites
B-lactam + B-lactamase inhibitors
Cat scratch disease pathogen
Bartonella henselae
Cat scratch disease symptoms
Papule or pustule, fever, lymphadenopathy (1-3 wks after exposure), most cases resolve spontaneously
Common pathogens in human bites
Staph, strep, Eikenella, Fusobacterium, Peptostrep, Prevotella, Porphyromonas
Boar/pig bite treatment
amoxicillin +/- ciprofloxacin
Rat bite fever pathogen
Streptobacillus moniliformis, Spirillum minus
Symptoms: fever, migratory polyarthralgias
Treat w/ penicillin
Endocarditis is most common complication
Seal finger pathogen
Mycoplasma spp causes a papular lesion
Treat w/ tetracyclines
Herpes B Virus characteristics
Endemic in macaques, persists in sensory ganglia for lifetime
Vesicular lesion, paresthesias –> seizures, ascending paralysis, respiratory failure
1st Phase of rabies
Flu-like
Discomfort, prickling/pruritic sensation at bite site
2nd Phase of rabies
Anxiety, confusion, agitation
Delerium, abnormal behavior, hallucinations, insomnia, hydrophobia
3rd Phase of rabies
Coma, death
What are the 4 sample sites required by the CDC to rule out rabies
Saliva, neck biopsy, serum, CSF
Name the fish that causes UTI problems
Candiru - crawls up urethra
Clinical presentation of tetanus
Painful muscular contractions of masseter, neck muscles, trunk muscles, abdomen, generalized spasms, seizures
Treatment of tetanus toxin
Tetanus immune globulin, toxoid booster, antibiotics, ventilation, sedation, muscle relaxants
Definition of wound infection
1 of the following: Organisms cultured, purulent drainage, abscess, and 2 of the following: localized pain/tenderness, redness, swelling, or heat
Major wound pathogen in Iraq
Actinetobacter baumannii
Predominate type of infection to come out of Afghanistan
Invasive fungal infections
Preferred antibiotic used in infected wounds (except burns)
Cefazolin
Key characteristics of Bacillus anthracis
Gram +, aerobic/facultatively anaerobic, spore-forming, rods forming long fillaments
List Bacillus anthracis virulence factors
Polypeptide capsule, toxins: edema toxin (EF+PA), lethal toxin (LF+PA). PA is protective antigen
How does B. anthracis’s lethal factor work?
Cleaves MAPKK to inhibit the MAPK signal transduction pathway in macrophages
How is B. anthracis transmitted to humans
Herbivores infected after grazing in infected soil, anthracis is then transmitted via contact w/ infected animal products, during inhalation-industrial settings
Also used as a bioterror weapon
Cutaneous anthrax clinical description
Most common type, contracted via exposure to animals, forms a black eschar (painless, edema), 80-90% complete resolution, can progress to bacteremia and death
GI anthrax clinical description
Rare, comes from ingestion of spore-contaminated meat. Ulcers form at site of invation –> regional lymphadenopathy, edema, and sepsis
Mortality >50%
Inhalational anthrax clinical description
Incubate 1-43 days, non-specific symptoms 3-5 days, then terminal phase
Terminal phase of inhalational anthrax symptoms
Hemorrhagic mediastinitis –> dyspnea, stridor, cyanosis, chest pain, chest wall edema, shock and death
Meningitis in 50%, GI hemorrhage in 90%
Chest X-ray features of B. anthracis
Widened mediastinum w/ pleural effusions w/out infiltrates
Inhalational anthrax treatment
Ciprofloxacin + Clindamycin + Rifampin
Anthrax vaccine
Inactivated - supernatant of attenuated, non-encapsulated strain, composed primarily of protective antigen
Yersinia pestis key characteristics
Gram (-) coccobacillus, rows well on MacConkey’s agar, facultative intracellular
MOA of tentani toxin
Interferes with NT release, blocking inhibitory impulses leading to unopposed spasms
What is Woolsorter’s disease
Inhalation of anthrax spores from contaminated wool
How do you diagnose Bubonic plague?
Wayson stain showing light blue bacteria
Rhabdoviridae (rabies) causes ____________ in infected neurons
Negri bodies
Rabies viral characteristics
Enveloped, -ssRNA, bullet shaped
Poxvirus characteristics
Big, brick shaped particle, ds-linear DNA, only DNA virus that replicates solely in the cytoplasm
How is smallpox spread
Secretions from mouth and noes and by material from pocks or scabs
Molluscum contagiosum (poxvirus) symptoms
Wart-like papular lesions on the face, back, and butt. Spread via towels in swimming pools and gyms. Self limiting after 4-6 months
What is an Orf lesion?
Vesicular lesion caused by poxvirus of sheep or goats
Post exposure prophylaxis for rabies should always include _______ and ________.
Passive antibody (HRIG) and vaccine
Important arenaviruses
Lymphocytic choriomeningitis virus, Lassa, and S. American hemorrhagic fevers
Key bunyavirus
Hantavirus
Lassa Virus reservior
Multimammate rate
Lassa Virus symptoms
Sore throat, facial swelling, deafness, “Swollen Baby Syndrome”
Lassa virus genome
Eneveloped ambisense RNA, grainy appearance
LCMV clinical picture
Presents as aseptic meningitis or encephalitis
Biphasic illness:
1. Fever, malaise, anorexia, muscle aches, HA
2. Meningitis or encephalitis
Mortality <1%
Hanta virus genome and transmission
3 -ssRNA segments (L, M, S)
Transmitted via inhalation of infected rodent excrement or direct skin contact
Hantavirus symptoms
Renal syndrome: fever, headache, hemorrhage, acute renal failure
or
Pulmonary syndrome: fever, chills, HA, nausea, blurred vision, pulmonary edema
What type of vaccine is the smallpox vaccine?
Live attenuated vaccine
SARS (coronavirus) genome
Enveloped ss+RNA
SARS clinical pictures
ARDS, history of travel to Asia, atypical pneumonia w/out alt. diagnosis
Arbovirus (VEE, EEE, WEE, West Nile etc) symptoms
Non-specific, flu-like, fever, rash, aches, chills, may go on to develop encephalitis
Japanese encephalitis symptoms
Rare to develop symptoms
Symptoms:
Fever, headache, vomiting, symptoms of an encephalitis, seizures in children
Yellow fever geographical distribution
West Africa, South America; two forms, urban and jungle
Yellow fever symptoms
Chills, fever, headache, generalized myalgias, nausea, vomiting
GI hemorrhage –> black vomit
Jaundice
50% mortality
Yellow fever vaccine
Live Attenuated Virus
Dengue virus geographical distribution
SE Asia, Africa, the Caribbean, and S. America
Transmitted by Aedes mosquitoes
Dengue virus symptoms
High fever, lymphadenopathy, myalgias, bone and joint pains, headache, and a maculopapular rash
La Crosse Virus
Bunyavirus
Most important cause of pediatric arbovirus encephalitis in US (Midwest)
Most infections are subclinical
Colorado Tick Fever structure and genome
Reovirus
Icosahedral, non-enveloped
dsRNA, 12 segments
Colorado Tick Fever transmission is from
Wood tick during spring/autum in west and northwest US, mostly CO
Pathogenesis of Colorado Tick Fever
Infects erythroid precursor cells and persists
Serious hemorrhagic disease results from infection of vascular endothelium
Symptoms: fever, chills, headache, myalgia, arthralgia, photophobia, lethargy
Rabbit fever pathogen
Francisella tularensis –> Tularemia
F. tularensis key characteristics
Facultatively intracellular in macrophages, gram (-), coccobacilli, needs cysteine media
Modes of transmission of Tularemia
Ingestion, inhalation, arthropod bites, mucous membranes
Types of tularemia infections
Ulceroglandular, Oculoglandular, Pneumonic, Typhoidal
Ulceroglandular tularemia
Follows primary infection of the skin, demarcated necrotic lesion, fever, locally inflamed and painful, 5% fatality
Oculoglandular tularemia
Contaminated eye w/ infected material, small % of cases
Pneumonic tularemia
Transmission via aerosol or via 2nd degree spread to the lungs, 30% fatality
Typhoidal tularemia
Follows ingestion of the organism, resembals typhoid: fever, malaise, cough, bloody nose, leukopenia, delirium, abdominal pain and distention, intestinal hemorrhage
Brucella/Undulate fever key characteristics
Facultative intracellular parasite of RES, multiplies w/in macrophages, Gram (-) rod
Brucella symptoms and mode of transmission
Ingestion of infected unpasteurized milk products or direct contact w/ infected animals, causes fever, night sweats, head ache, chills, myalgias, weight loss
Complications of chronic Brucella
Hepatic lesions arthritis, meningitis, endocarditis
Classic trench fever is caused by…
Bartonella quintana
Bartonella quintana causes ________ in immunocompetent patients and ________ in immunocompromised patients.
- Febrile bacteremia
2. Bacillary angiomatosis and endocarditis
Bartonella bacilliformis causes
Carrion’s disease
1st phase: Hemolytic anemia
2nd phase: Verruga peruana (leg lesions)
Carried by sandfly
Bartonella henselae (cat scratch disease) causes __________ in immunocompromised.
Bacillary angiomatosis - endothelia colonization and proliferation
Members of the family Rickettsiaceae are obligate __________ bacteria that are usually transmitted by ____________.
- intracellular
2. arthropods, usually tics
Rocky mountain spotted fever pathogen, vector, and reservior
Rickettsia rickettsia
Dog ticks are the vector
Wild rodents are the reservior
Rickettsia spp. key characteristics
obligate intracellular, gram (-), coccobacilli, visible on Giemsa stain
Spread of Rickettsia from cell-to-cell involves _____________
Actin polymerization
Clinical manifestations of Rickettsial diseases
Skin rash, fever, severe headache, malaise, prostration, and hepatosplenomegaly
Pathophys of Rickettsial diseases
Vasculitis caused by proliferation of the organisms in the endothelial lining of small blood vessels
Epidemic typhus pathogen
Rickettsia prowazekii
Rickettsia typhi
Cause of endemic or murine typhus, occurs worldwide, flea borne, rarely fatal
Erlickia and Anaplasma live in ___________ cells
Mammalian hematopoetic cells
Anaplasma phagocytophilum primarily infects?
Granulocytes
Erlichia symptoms
Rocky mountain spotted fever w/out a rash
Q-fever pathogen
Coxiella burnetii
Q-fever symptoms
Atypical pneumonia w/ flu-like symptoms, sometimes endocarditis
Infection is from cattle, goats, and sheep
Coxiella virulence factors
Endospore/pseudospore form
Name and describe the stages of Lyme disease
Stage 1: Localized infection - erythema migrans at bite site
Stage 2: Disseminated infection - secondary annular skin lesions an systemic symptoms such as severe malaise and fatigue, Bell’s palsy
Stage 3: Persistent infection - characterized by arthritis, meningoencephalitis, neuropathies
Lyme disease clinical case definition
Either
- erythema migrans or
- one late manifestation (MSK, Nervous system, CV involvement) and lab confirmation
Diagnostic tests for Lyme
Giesma stain, biopsy of erythema migrans, acute vs convalescent serum
Lyme treatment
Oral doxycycline or IV antibiotics for arthritis or neurological abnormalites
Causative agent of Southern Tick Associated Rash Illness (STARI) and symptoms
Amblyomma americanum causes a Lyme like disease
Relapsing fever
Caused by other spp of Borrelia, characterized by recurrent episodes of fever separated by asymptomatic intervals, vector is body louse or soft shelled tick
Louse-borne relapsing fever
Borrelia recurrentis, epidemic form
Endemic relapsing fever
Tick-borne, has animal reserviors
Leptospirosis clinical picture
Stage 1:
Acute febrile illness, conjunctival suffusion, photophobia, severe muscle aches
Stage 2:
Immune phase w/ IgM appearance and meningismus, WBCs in CSF
Transmission of Leptospirosis
Humans come into contact with infected animal urine in water or soil
Treatment of Leptospirosis
Doxycycline or penicillin
Weil’s disease
Most severe form of Leptospirosis caused by serogroup icterohaemorrhagiae –> renal failure, hepatitis, haundice, altered mental status, multi-organ hemorrhage
