LOs: 15-16 Flashcards Preview

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Flashcards in LOs: 15-16 Deck (28):
1

15 Rhinitis:

Definition

Cardinal symptom

Usual etiologies (3)

Treatment

- Inflammation of nasal mucosa
- May be accompanied by sinusitis, pharyngitis, headache, & constitutional symptoms

“common cold”

- Rhinovirus
- Coronavirus
- Respiratory Syncytial Virus (RSV)

Symptomatic only (except RSV)

2

15 Sinusitis:

Definition

Usual etiology

Common bacterial etiologies (3)

Nasal discharge

- Inflammation of the sinuses
- Bacterial sinusitis may present w/ facial pain/tenderness & high fever

Rhinovirus

- Streptococcus pneumoniae (GPC)
- Haemophilus influenzae (GN)
- May have some anaerobic component

Presence of yellow or green nasal discharge DOES NOT distinguish viral from bacterial etiologies

3

15 Otitis Media:

Definition

Common in...

Usual etiology

Common bacterial etiologies (2)

- Middle ear infection
- May accompany the common cold

Children

Viruses

- Streptococcus pneumoniae (GPC)
- Haemophilus influenza (GN)

4

15 Pharyngitis/Tonsillitis:

Definition

Usual etiologies (2)

Most common bacterial etiology

- Inflammation of the pharynx/tonsils
- Presents w/ sore throat

Viral
- Rhinovirus
- Coronavirus

Streptococcus pyogens (GPC)
- AKA GroupA Streptococcus (GAS) as the cause of “Strep throat”

5

15 Acute Bronchitis:

Definition

Smoking

Exacerbations

Usual etiologies (3)

Usual bacterial etiologies (3)

- Presents w/ cough, typically productive of sputum
- May sometimes be associated w/ wheeze (bronchospasm)

Heavy smokers may develop emphysema or chronic bronchitis (cough productive of sputum throughout the year)

Viral or bacterial infections may cause exacerbations of bronchitis (“acute on chronic”)

Viral
- Rhinovirus
- Adenovirus
- Influenzavirus

- Streptococcus pneumoniae (GPC)
- Haemophilus influenzae (GN)
- Moraxella catarrhalis (GN)

6

15 Influenza:

Definition

Caused by...

Isolated from...

Treatment

Sudden onset of chills, accompanied by severe muscle aches, fever, & cough

Influenza virus (A or B)

Nose or pharynx

Specific anti-influenza drugs are available but only effective if give in the first 36-48 hours after the first onset of symptoms

7

15 Community-Acquired Pneumonia:

Cardinal symptoms

Most common cause

Other common causes (2)

Atypical causes (3)

Cough productive of sputum, pleuritic chest pain, shortness of breath and fever

Streptococcus pneumoniae

- Haemophilus influenzae
- Moraxella catarrhalis

- Chlamydophila pneumoniae
- Legionella pneumophila
- Mycoplasma pneumoniae

8

15 Hospital-Acquired Pneumonia:

Prone pts

Common causes (5)

Ventilator-associated penumonia (VAP): pts who are mechanically ventilated

- Pseudomonas aeruginosa
- Staphylococcus aureus
- Acinetobacter spp.
- Enterobacter cloacae
- Klebsiella pneumoniae

9

15 Urinary Tract Infection:

Common in...

Cystitis
- Symptoms
- Etiologies (2)

Acute pyelonephritis
- Symptoms
- Most common cause
- Catheterization causes (4)

Young women

- Dysuria (burning or stinging on passing urine) and increased frequency of passage of urine
- Escherichia coli
& Staphylococcus saprophyticus

- Fever & flank pain
- E. coli
- E. coli, Enterococcus faecalis, Proteus mirabilis and Candida albicans

10

15 Bloodstream Infection:

Bacteremia

Severe sepsis

Vascular line related bacteremia

Causes of vascular line related bactermia (2)

Cause of prolonged bacteremia

Bacteria in the bloodstream

Result of bacteremia, physiologic functions are affected

Intravascular lines or devices may become bacteremic because these foreign bodies serve as a ready portal for bacteria from skin to the blood

- Staphylococcus aureus
- Coagulase negative staphylococci

Endovascular source
- Intravascular device (catheter, pacemaker)
- Heart valve (endocarditis)

11

15 Meningitis and Encephalitis:

Encephalitis

Meningitis

Meningoencephalitis

Etiologies of encephalitis (2)

Causes of meningitis (4)

Inflammation of the brain

Inflammation of the meninges

Inflammation of both the brain and the meninges

- Herpes simplex virus
- Vector borne infections (for example, West Nile virus)

- Neisseria meningitidis
- Streptococcus pneumonia
- Listeria monocytogenes
- The enteroviruses

12

15 Sexually Transmitted Infections:

Causes of urethritis (2)

Causes of genital ulcers (2)

Causes of genital warts (1)

- Chlamydia trachomatis
- Neisseria gonorrhoeae

- Herpes simplex virus
- Syphilis (Treponema pallidum)

Human papillomavirus

13

15 Diarrhea:

Causes outside hospital
- Bacteria (4)
- Protozoa (2)
- Viruses (2)

Cause within hospital (1)

Bacteria
- Salmonella
- Campylobacter
- Shigella
- E. coli

Protozoa
- Giardia lamblia
- Cryptosporidium

Viruses
- Rotavirus
- Norovirus

Clostridium difficile

14

15 Cutaneous Infections:

Cauess of dermatitis (2)

Causes of superficial cellulitis (1)

Causes of abscesses (1)

Causes of systemic (generalized) infections (3)

Causes of chronic ulcers (diabetics) (3)

- Dermatophytes
- Candida

Streptococcus

Staphylococcus

Infective endocarditis
- Pseudomonas aeruginosa bacteremia
- Disseminated fungal infections

- First gram+ cocci (Staph/Strep)
- Then gram- (E. coli) & Enterococcus
- Then resistant gram- (Pseudomonas)

15

15 Infection Susceptibility & Immunodeficiencies:

Immunodeficiency definition

Opportunistic infections
- Definition
- Examples (4)

A state in which the response of the host to a foreign antigen is not normal (congenital or acquired)

- Normal colonizing organisms that exploit some weakness in the host defense

- Splenectomy
- Neutropenia
- T-cell depletion (HIV, transplant)
- Hypogammaglobulinemia

16

15 Opportunistic Organisms:

Abnormalities in opsonization and reticulo-endothelial system (RES)
- Complement deficiency: Lupus (SLE)
- Asplenia: liver cirrhosis, splenectomy, sickle cell disease

Encapsulated organisms (3)

Haemophilus influenzae

Neisseria meningitidis

Streptococcus pneumoniae

17

15 Opportunistic Organisms:

Granulocyte or neutrophil abnormalities
- Chronic granulomatous disease (CGD)
- Neutropenia (low # of neutrophils)

Catalase positive organisms (3)

Staphylococcus aureus

Aspergillus

Pseudomonas aeruginosa

18

15 Opportunistic Organisms:

Lymphocytes
- B cells
-- IgA deficiency
-- IgG deficiency (multiple myeloma, common variable imm-def. (CVID))
- T cells
-- HIV/AIDS
-- Immunosuppressant medications

Protozoa (1)

Encapsulated organisms (3)

Fungi & yeasts (3)

Parasites (1)

Mycobacteria (2)

Viruses (6)

Giardia

Neisseria meningitidis
Haemophilus influenzae
Streptococcus pneumonia

Cryptococcus
Candida
Pneumocystis jaroveci

Toxoplasma

Tuberculosis
MAC

HSV
VZV
CMV
KSHV
HPV
JC

19

16 Most common entry routes for pathogens causing exogenous infections (6)

Inhalation (respiratory)
- M. tuberculosis
- Influenza virus

Ingestion - Salmonella spp.
- Rotavirus

Blood - Hepatitis B virus

Arthropods - Borrelia burgdorferi
- Plasmodium spp.

STI - HIV virus
- N. gonorrhoeae

Wounds - C. perfringens

20

16 Intoxications vs. Infections:

Intoxications

Infections
- Invasive pathogens acquired by ingestion
- In vivo enterotoxin production by ingestion-acquired pathogens

Ingestion of preformed toxin is sufficient to obtain disease
- Often involve heat- and pH-stable toxins
- Symptoms develop quickly
- Symptoms often involve the GI tract: vomiting, diarrhea, cramps

Ingested pathogen must be present in the body
- Cause GI symptoms (EHEC also damages kidneys)
- Symptoms develop slowly

- Cause inflammation & GI symptoms
- Remain in GI tract or disseminate

- Produce toxins after becoming in present in GI tract
- Noninvasive (except Shigella)

21

16 Transmission & Initial Disease Symptoms:

Fecal-oral contamination

Food poisoning

Waterborne infections

Most ingestion-acquired pathogens are transmitted this way

- Symptoms: diarrhea, cramping, vomiting, sometimes fever
- Result from incomplete cooking, poor sanitation, & poor food storage

- From aging water or equipment breakdowns
- Pathogens highly resistant to chlorination
- Great potential public health threat

22

16 Most Common Food Poisoning Bacteria (6)

Nontyphoid Salmonella
Clostridium perfringens
Shigella spp.
Campylobacter jejuni
E. coli
Staphylococcus aureus

23

16 Defenses in the GI tract & how ingestion-acquired pathogens overcome these defenses (3)

(1) Physical & chemical defenses

GI tract: gastric acid, bile, intestinal proteases, mucus, intestinal motility

Pathogens: ingestion in large numbers, acid/bile resistance, ingested in food, produce urease to raise pH, shelter in mucus, adherence

(2) Immune defenses

GI tract: IgA, GALT

Pathogens: countermeasures against immune defenses

(3) Normal microbial flora

GI tract: protect against GI pathogens

Pathogens: produce pili to adhere to unoccupied sites in the GI tract

24

16 Campylobacter jejuni:

Biologic Characteristics

Reservoirs/Transmission

Pathogenesis

Prevention/Treatment

- Motile
- Curved/gull winged shaped
- Oxidase positive
- Gram-negative rods
- Fastidious
- Microaerophilic
- Grow best at 42*C

R: animal (zoonotic)
T: contaminated food (esp poultry) & water

Adhesions (attachment) & LPS (inflammation)

- Ingestion, attaches to intestine, invades, induces inflammation
- Symptoms start within a few days & resolve ~5 days later
- Symptoms: cramps, diarrhea, fever

P: hygiene, cooking, no vaccine
T: symptomatic therapy, fluid replacement, antimicrobials (severe)

25

16 Giardia spp.:

Biologic Characteristics

Reservoirs/Transmission

Pathogenesis

Prevention/Treatment

- Vegetative form (trophozoites) & infectious form (cysts)
- Ingested cysts transport to small intestines to become trophozoites
- Resistant to chlorination

R: wild animals
T: contaminated water & food, fecal-oral

- Infectious cysts are ingested, become trophozoites, & multiply in the duodenum
- Symptoms start within 1-3 weeks & resolve 1-4 weeks later
- Symptoms: explosive, sudden onset diarrhea involving a foul-smelling, greasy stool devoid of blood or mucus

P: water treatment, hygiene, no vaccine
T: metronidazole

26

16 Cryptosporidium parvum:

Biologic Characteristics

Reservoirs/Transmission

Pathogenesis

Prevention/Treatment

- Intracellular protozoan
- Multiplies in GI tract by sexual & asexual reproduction
- Sporozoites --> trophozoites --> merozoites --> oocysts
- Shed in stool

R: zoonotic (farm animals, pets)
T: contaminated water, fecal-oral

- Oocysts ingested & --> sporozoites
- Sporozoites invade enterocytes under brush border & --> trophozoites (inflammation)
- Symptoms start 1 week later & persist for 1-2 weeks
- More severe in immunocompromised (chronic --> death)

P: hygiene, water treatment
T: Nitazoxanide for immunocompetent, antiretroviral & supportive therapy in immunocompromised

27

16 Rotavirus:

Biologic Characteristics

Reservoirs/Transmission

Virulence Factors

Pathogenesis

Prevention/Treatment

- Reovirus (dsRNA, 11 segments)
- Icosahedral capsid
- No envelope
- Acid resistant

R: humans
T: fecal-oral, withstand acidity, winter

Nonstructural protein (NSP4): enterotoxin

- Ingestion, multiples in intestine
- Symptoms start within 48 hours & continue for days to a week
- Symptoms: diarrhea, vomiting, fever
- Most common diarrhea cause in children <2

P: new vaccine
T: restore fluid/electrolyte balance

28

16 Hepatitis A Virus (HAV):

Biologic Characteristics

Reservoirs/Transmission

Pathogenesis

Prevention/Treatment

- Picornavirus, +ssRNA
- Nonenveloped
- 1 serotype

R: humans
T: fecal-oral, common worldwide, Chi Chi's outbreak

- Ingestion, replicates in gut
- If sufficient HAV-neutralizing antibodies, no further development
- If not, HAV invades blood, spreads to liver, & causes acute inflammatory disease & jaundice
- Acute: completely recovers within 2 months, provides life-long immunity
- Fulminant hepatitis can be fatal

Hygiene, recent HAV exposure, HAV vaccine