What are the normal microbiota of the skin?
Gram-positive, salt-tolerant bacteria: Staphylococci, Micrococci, and Diphtheroids
Name several Staphylococcal skin infections.
S. epidermis
S. aureus: folliculitis (infections of the hair follicles); impetigo (vesicles on skin, treat with penicillin); toxic shock syndrome (fever, vomiting, sunburn-like rash, follows with shock and possible organ failure, originally associated wit
Name several Pseudomonad infections
Pseudomonas aeruginosa
Otitis externa, "swimmer's ear"
Common and serious in severe burn victims (Infection: blue-green pus caused by pigment pyocyanin)
How is acne classified? When does it occur? How is it treated?
Classified by type of lesion: comedonal, inflammatory, nodular
Comedonal acne occurs when sebum channels are blocked with shed skin cells
Treated with topical agents; do not affect sebum formation
From where does inflammatory acne originate? How is it treated?
Inflammatory acne-from bacterial effects: Propionibacterium acnes; Gram-positive, anaerobic rod; found on skin
Treatment: Preventing sebum formation (isotretinoin); drug is teratogenic (causes birth defects in fetus); Antibiotics
What causes warts? How are they treated?
Papillomaviruses; generally benign skin growths; viruses
Treatment: removal through Cryotherapy, electrodesiccation, burning with acid, prescription topical agents (stimulate production antiviral interferons), lasers; Some cancers are associated with papi
Describe several features of herpes viruses
Varicella-zoster virus (human herpes virus 3)
Transmitted by the respiratory route
Causes pus-filled vesicles
Virus may remain latent in dorsal root ganglia
Describe several features of shingles (Herpes zoster)
Reactivation of latent HHV-3 releases viruses that move along peripheral nerves to skin
Burning or stinging type of pain is a symptom
How is herpes simplex 1 and 2 transmitted? What are the physical signs of herpes simplex 1 and 2?
Human herpes virus 1 and HHV-2; transmitted orally/respiratory and sexually respectively
Cold sores or fever blisters (vesicles on lips)
HHV-2 usual cause of genital warts
Describe several features of measles
Measles virus
Transmitted by respiratory route
Humans only reservoir; can be potentially eliminated
Macular rash and Koplik's spots
Prevented by vaccination
Describe several features of rubella (German measles)
Milder than rubeola
Sx: Macular rash and fever
Congenital rubella syndrome causes severe fetal damage
Prevented by vaccination
Describe several features of cutaneous mycoses
Dermatomycoses, aka tineas or ringworm
Metabolize keratin
Tinea capitis, tinea cruris, tinea pedis (ringworm of scalp, groin and feet)
Treatment: non-Rx topical agents (miconazole), antibiotics (griseofulvin)
Describe several features of candidiasis
Candida albicans (yeast)
Candidiasis may result from suppression of competing bacteria by antibiotics
Occurs in skin; mucous membranes of genitourinary tract and mouth
Thrush is an infection of mucous membranes of mouth
Topical treatment with miconazole o
Describe the bacterial diseases of the eye
Conjunctivitis (pinkeye): Haemophilus influenza - most common bact. Cause; Various microbes; Associated with unsanitary contact lenses
Neonatal gonorrheal ophthalmia: Neisseria gonorrhoeae; Transmitted to a newborn's eyes during passage through the birth
How do microbes enter the nervous system?
Skull or backbone fractures
Medical procedures
Along peripheral nerves
Blood or lymph
What are two types of microbial diseases of the nervous system?
Meningitis: Inflammation of meninges.
Encephalitis: Inflammation of the brain.
Describe several features of bacterial meningitis
Fever, headache, and stiff neck
Followed by nausea and vomiting
May progress to convulsions and coma
Diagnosis by Gram stain or latex agglutination of CSF
3 species: S. pneumoniae (G+), H. influenzae, N. meningititis (both G-). All have a capsule
Treated
Describe several features of haemophilus influenza meningitis
Occurs mostly in children
Caused by normal throat microbiota
Describe several features of Neisseria Meningitis, Meningococcal Meningitis
N. meningitidis
Begins as throat infection, rash
Describe several features of Streptococcus pneumoniae Meningitis (Pneumococcal Meningitis)
70% of people are healthy nasopharyngeal carriers
Causes meningitis, pneumonia and otitis media
Most common in children (1 month to 4 years)
Describe several features of Listeriosis
Listeria monocytogenes
Gram-negative aerobic rod
Usually foodborne; it can be transmitted to fetus
Reproduce in phagocytes
Describe several features of Tetanus
Clostridium tetani
Grows in deep wounds.
Tetanospasmin released from dead bacteria blocks relaxation pathway in muscles (early sx: lockjaw)
Prevention by vaccination with tetanus toxoid (DTP) and booster (dT) shots
Describe several features of botulism
Clostridium botulinum
Intoxication comes from ingesting botulinal toxin.
Botulinal toxin blocks release of neurotransmitter causing flaccid paralysis.
Prevention: Proper canning; Nitrites prevent endospore germination in sausages.
Infant botulism results
Describe several features of rabies virus (Rhabdovirus)
Transmitted by animal bite.
Virus multiplies in skeletal muscles, then brain cells causing encephalitis.
Initial symptoms may include muscle spasms of the mouth and pharynx and hydrophobia.
Postexposure treatment: Vaccine plus immune globulin.
Describe several features of Cryptococcus Neoformans Meningitis (Cryptococcosis)
Soil fungus associated with pigeon and chicken droppings.
Transmitted by the respiratory route; infection of the lungs but can spread through blood to the CNS
Expressed as chronic meningitis
Define sepsis, severe sepsis, and septic shock
Sepsis: Bacteria growing in the blood
Severe sepsis: Decrease in blood pressure
Septic shock: Low blood pressure cannot be controlled
What are the two types of sepsis?
Gram-negative sepsis: Endotoxins caused blood pressure decrease; Antibiotics can worsen condition by killing bacteria.
Gram-positive sepsis: Nosocomial infections (Staphylococcus aureus, Streptococcus pyogenes, Group B streptococcus, Enterococcus faecium
Describe the bacterial infections of the heart
Endocarditis: Inflammation of the endocardium
Subacute bacterial endocarditis: Alpha-hemolytic streptococci from mouth (released by tooth extraction, tonsilectomy)
Acute bacterial endocarditis: Staphylococcus aureus from mouth; rapid destruction
Pericardi
Describe several features of cutaneous anthrax
Anthrax lesion
The swelling and formation of a black scab around the point of infection
Describe several features of gangrene
Ischemia: Loss of blood supply to tissue
Necrosis: Death of tissue
Gangrene: Death of soft tissue
Gas gangrene: Clostridium perfringens, gram-positive, endospore-forming anaerobic rod, grows in necrotic tissue; Gas in tissue, swells up; ultimately systemi
Describe several features of lyme disease
Borrelia burgdorferi (spirochete)
Reservoir: Deer
Vector: Ticks
Only 1% of tick bites result in Lyme disease
What are the stages of lyme disease?
First symptom: Bull's eye rash
Second phase: Irregular heartbeat, encephalitis
Third phase: Arthritis
Spotted Fevers (Rocky Mountain Spotted Fever)
Rickettsia rickettsii
Measles-like rash except that the rash appears on palms and soles too.
Human Herpes Virus 4 Infections
Epstein-Barr virus (HHV-4)
Infectious Mononucleosis: Childhood infections are asymptomatic; Transmitted via saliva; Characterized by proliferation of monocytes
Malaria
Plasmodium vivax, P. ovale, P. malariae, P. falciparum
P. falciparum most dangerous
Anopheles - mosquito - infection initiated by mosquito bite
Mosquito control and breaking the chain of transmission by using bed nets
Symptoms include chills and fever, vo
What are the microbial diseases of the upper respiratory system?
Laryngitis: S. pneumoniae, S. pyogenes, viruses
Tonsillitis: S. pneumoniae, S. pyogenes, viruses
Sinusitis: Bacteria
Epiglottitis: H. influenza
Streptococcal Pharyngitis (Strep Throat)
Streptococcus pyogenes (G+), Group A strep
Resistant to phagocytosis
Diagnosis by indirect agglutination
Diphtheria
Corynebacterium diphtheriae: Gram-positive rod
Diphtheria membrane of fibrin, dead tissue, and bacteria; can block airway
Diphtheria toxin produced by lysogenized C. diphtheriae
Prevented by DTaP and Td vaccine (Diphtheria toxoid)
Cutaneous diphtheria: In
What viruses cause the common cold?
Rhinoviruses (50%)
Coronaviruses (15-20%)
What are the microbial diseases of the lower respiratory system?
Bacteria, viruses, and fungi cause: Bronchitis; Bronchiolitis; Pneumonia
Tuberculosis
Mycobacterium tuberculosis: transmitted from human to human.
M. avium-intracellulare complex infects people with late stage HIV infection.
Considered to be emerging disease in US due to recent increase in number of cases.
Treatment of tuberculosis: Prolon
Pneumomoccal Pneumonia
Sx: fever, difficulty breathing, chest pain
Streptococcus pneumonia
Viral Pneumonia
Viral pneumonia as a complication of influenza, measles, or chickenpox.
Viral etiology suspected if no cause determined.
Influenza
Chills, fever, headache, and muscle aches (no intestinal symptoms)
1% mortality due to secondary bacterial infections
Vaccine for high-risk individuals
Differentiate antigenic shift from antigenic drift in influenza
Antigenic shift: Changes in H and N spikes; Probably due to genetic recombination between different strains infecting the same cell
Antigenic drift: Mutations in genes encoding H or N spikes; May involve only 1 amino acid.; Allows virus to avoid mucosal I
Influenza Serotypes
A: Causes most epidemics
B: Moderate, local outbreaks
C: Mild disease
What are the normal microbiota of the large intestine?
Bacteroides
E. coli
Enterobacter
Klebsiella
Lactobacillus
Proteus
Staphylococcal Food Poisoning
Staphylococcus aureus enterotoxin is a superantigen.
Salmonellosis
Salmonella enterica serovars such as S. typhimurium
Mortality (<1%) due to septic shock caused by endotoxin
Helicobacter Peptic Ulcer Disease
Causes peptic ulcer disease; gastric and duodenal ulcers
H. pylori causes stomach cancer
Clostridium Infections
Clostridium perfringens Gastroenteritis: Grow in intestinal tract, producing exotoxin; Associated with meats contaminated with intestinal contents
Clostridium difficile (G+, endo forming)-associated diarrhea: Grow following antibiotic therapy; Associated
Mumps
Mumps virus
Enters through respiratory tract
Infects parotid glands
Prevented with MMR vaccine
Hepatitis
Inflammation of the liver
5 different viruses of cause: A, B, C, D, E
Hepatitis may result from drug or chemical toxicity, EB virus, CMV, or the hepatitis viruses
HBV high incidence in healthcare, drug users because of blood contact
Describe several features of normal microbiota of the urinary and reproductive systems?
Urinary bladder and upper urinary tract sterile
Lactobacilli predominant in the vagina
>1,000 bacteria/ml or 100 coliforms/ml of urine indicates infection
Gonorrhea
Neisseria gonorrhoeae
Attaches to oral or urogenital mucosa by fimbriae
Females may be asymptomatic; males have painful urination and pus discharge
Treatment is with antibiotics
If left untreated, may result in: Endocarditis; Meningitis; Arthritis; Ophtha
Pelvic Inflammatory Disease (PID)
Umbrella term for infection of female pelvic organs; complications can develop
Polymicrobial: N. gonorrhoeae; C. trachomatis; Can block uterine tubes; Chronic abdominal pain
Syphilis
Treponema pallidum
Invades mucosa or through skin breaks.
Primary stage: Chancre at site of infection
Secondary: Skin and mucosal rashes
Latent period: No symptoms
Tertiary: Gummas on many organs; local destruction, not fatal
Congenital: Neurological dama
Genital Warts
Human papillomaviruses HPV
HPV 16 causes cervical cancer and cancer of the penis.
DNA test is needed to detect cancer-causing strains.
Vaccination against 4 HPV strains
Candidiasis
Candida albicans, infection a result of opportunistic action
Grows on mucosa of mouth, intestinal tract, and genitourinary tract
Commonly heard "Yeast infection