World Diseases Exam 2

antibiotics

chemical compounds synthesized by one microbe to selectively kill other microbes

Kirby-Bauer assay

disk diffusion test to measure the zone of inhibition around filtered-paper disks impregnated with antibiotics

antibiotics that target cell wall synthesis

penicillins, cephalosporins, bacitracin, vancomycin

antibiotics that target cell membrane integrity

polymyxins, gramicidin (antibacterial), amphotericin, imadazoles (anti-fungal)

antibiotics that target mycolic acid synthesis

isoniazid (mycobacterium tuberculosis)

antibiotics that target DNA replication and integrity

quinolones, metronidazole, nitrofurantoin, some antiviral compounds

antibiotics that target transcription

rifampin, fidaxomicin (clostridioides dificile)

antibiotics that target protein synthesis

chloramphenicol, tetracyclines, aminoglycosides, macrolides, lincosamides

antibiotics that target intermediary metabolism

sulfonamides, trimethoprim (inhibit folic acid synthesis), bedaquiline (inhibits ATP synthase in M. tuberculosis), platensimycin (inhibits bacterial fatty acid synthesis)

What URT viral infection has 200 viral subtypes?

the common cold

What is the most common cause of common colds (70-80%)?

rhinoviruses

viral sinusitis

infection of the upper airways, inflammation/congestion of the sinuses, resolves on its own

respiratory syncytial virus (RSV)

transmitted from person to person, most common cause of bronchiolitis and pneumonia among infants and children under 1 age

How does RSV occur?

comes in contact with mucous membranes of eyes, with the mouth or nose, through inhalation of droplets from a sneeze or cough

What are influenza virus types based on?

antigenic determinants

Type A influenza

cause of epidemics and occasional pandemics, can infect animals and people, constantly changing

Type B influenza

found mostly in humans and results in milder illness, doesn’t cause pandemics

Type C influenza

causes only mild disease, doesn’t cause epidemics or pandemics

Hemagglutinin

transmembrane protein that forms the spikes on the viral surface, binds to N-acetylneuraminic (sialic) acid on the surface of the respiratory cells to gain entry

neuraminidase

on surface releases budding virus from host cell

M2

releases viral genome into host cell cytoplasm

antigenic shift

eight RNA segments of each flu genome will uncoat, mix in the cytoplasm, resort to form a new influenza virus containing a new form of the hemagglutinin gene

antigenic drift

smaller mutations in the HA and NA genes

What does coronavirus look like?

single-stranded, positive-sense, enveloped RNA virus

severe cases of covid include a

cytokine storm

many cases of covid are

asymptomatic and can be transferred in asymptomatic form

what is croup also known as

laryngotracheobronchitis (LTB)

what age group is at the highest risk for contracting croup?

6 months - 5 years old

what causes croup

parainfluenza virus types 1 & 2

symptoms of croup are

fever, running nose, “barking” cough (caused by swelling of larynx)

viral URT infections

common cold, viral sinusitis

viral LRT infections

RSV, influenza, COVID, croup

bacterial URT infections

otitis media, bacterial sinusitis, diphtheria, whooping cough, bronchitis, pharyngitis, tonsilitis, laryngitis, peritonsillar abscess

bacterial LRT infections

pneumonia, Legionnaire’s disease, tuberculosis

otitis media can be caused by both

viruses and gram negative/positive bacteria

what is the most common sick child visit?

otitis media

3 bacterial species that frequently cause acute otitis media?

streptococcus pneumoniae, haemophilus influenzae, moraxella catarrhalis

bacterial sinusitis

often accompanies middle ear infection in children and pneumonia in adults, inflammation/congestion obstructs the sinuses and mucus flow, treated with antibiotics

bacterial sinusitis symptoms

pressure behind the eyes, pain in the face, foul-smelling nasal discharge/breath

streptococcal pharyngitis

strep throat

streptococcal pharyngitis transmission

spreads through person to person contact and indirect contact with items contaminated by secretions

streptococcal pharyngitis symptoms

sudden onset of high fever and sore throat, tender enlarged cervical lymph nodes, exudate on tonsils, absence of a cough

streptococcal pyogenes

produces exotoxins called streptococcal pyogenes exotoxins (SPEs)

what do SPEs cause

scarlet fever: fever and red rash (head and neck, trunk, then legs) and strawberry tongue

streptococcal pharyngitis diagnosis

rapid strep test - immunoassay technology and highly specific for S. pyogenes

acute rheumatic fever (sequalae of post streptococcal infections)

young children (4-9 years old), high fever, damage to heart, joints, skin, or nervous system, cross reactive antibodies, T-cells, and complement, glomerulonephritis (kidney disease)

what causes diptheria

corynebacterium diphtheria, gram-positive rod

diphtheria characterization

presence of pseudomembrane

how is diphtheria treated

simultaneous antibiotics and antitoxins

diphtheria vaccine

inactivated diphtheria toxin that is part of DTap vaccinations

what causes whooping cough

gram-negative bacillus Bordetella pertussis

whooping cough transmission

inhalation of acquired droplets coughed by someone with illness

how long is whooping cough incubation period

7-21 days

whooping cough stages

catarrhal, paroxysmal, convalescent

catarrhal stage

symptoms of upper respiratory infection

paroxysmal stage

violent paroxysmal (rapidly repeatedly) cough, followed by a deep breath that makes a whooping noise

convalescent stage

paroxysms gradually disappear during the next 2-3 weeks as patient recovers

whooping cough (pertussis) vaccine for young children

DTap: 2, 4, & 6 months, 15-18 months, 4-6 years

whooping cough (pertussis) vaccine for preteens

TDap: 11-12 years

whooping cough (pertussis) vaccine for pregnant women

TDap: 27-36th week of each pregnancy

whooping cough (pertussis) vaccine for adults

TDap: anytime for those who have never received it, includes adults with COPD or asthma

bronchitis is

acute and self-limiting and has multiple viral and bacterial etiologies

productive cough

only presenting symptom of bronchitis

acute bronchitis

suspected when patient’s cough persists for more than 5 days

pneumonia

infection that causes lung inflammation

community acquired pneumonia

acquired outside of a hospital

atypical pneumonia

affect multiple organs, usually produce a normal WBC count, and symptoms gradually appear and mimic URT infections at the onset

atypical pneumonia pathogens

mycoplasma pneumonia, legionella, chlamydophila

typical pneumonia pathogen

streptococcus pneumoniae

legionellosis (Legionnaire’s disease) pathogen

legionella pneumophila; gram-negative bacterium

what does legionella pneumophila cause

atypical pneumonia

legionellosis transmission

contaminates water sources (lakes, hot water/AC systems of large buildings, etc), transmission via inhalation of contaminated water droplets

characteristic of legionellosis

after phagocytosis, bacterium prevents the fusion of the phagosome with the lysosome

mycoplasma pneumoniae

lacks a rigid cell wall and usually exist in filamentous form; smallest known species of bacteria

mycoplasma pneumoniae symptoms

headache, malaise, low-grade fever, progression to nonproductive cough, chills

most common cause of hospital aquired pneumonia

pseudomonas aeruginosa

pseudomonas aeuroginosa features

opportunistic, gram negative pathogen; large # of virulence factors; major contributor to pneumonia and mortality in cystic fibrosis patients

mycobacterium tuberculosis

acid-fast bacteria, cases are on the rise in developed nations due to HIV and a growing indigent population

multidrug resistant (MDR) tuberculosis

produces rapid onset (fulminant) and fatal disease among patients with HIV; highly infectious even to healthy people without HIV

tuberculosis transmission

person to person (no animal reservoir); aersolizing of respiratory tracts

tuberculosis pathogenesis

bacteria enter lung, are phagocytized by macrophages, and survive sheltered within modified phagolysosomes

how does a delayed-hype hypersenstitivity reaction to TB develop?

small hard tubercules (granulomas) form around the site of infection, tubercules develop into caseous lesions that have a cheese-like consistency and can calcify into hardened Ghon complexes seen on x-rays

latent tuberculosis

bacilli contained by immune systems; not infectious

primary/active TB

characterized by a productive cough that generates sputum, fever, night sweats, and weight loss

patients with active TB are

contagious

TB identification features

calcified Ghon complex in x-rays, cavity formations in the lungs on x-ray

gastritis

inflammation of stomach lining

gastroenteritis

inflammation along the GI tract

enteritis

inflammation of the small intestine

enterocolitis

inflammation of the colon and small intestine

colitis

inflammation of the colon

osmotic diarrhea

intestinal osmolarity is higher than internal osmolarity, causing water to leave cells

what kind of pathogens cause osmotic diarrhea

that prevent nutrient absorption

secretory diarrhea

increased in secretion causes electrolytes to leave, leading to imbalance

secretory diarrhea pathogen

pathogens that cause ion secretion cause secretory diarrhea

inflammatory diarrhea

inflammatory cytokines damage mucosal cells and prevent absorption of nutrients and water

inflammatory diarrhea pathogens

shigella and salmonella

motility related diarrhea

food moves too quickly through the intestinal tract and nutrients aren’t absorbed

motility related diarrhea pathogens

enterotoxins and rotavirus