Microbiology Ch 24 review

• -nose
• -Pharynx (throat)
• -Middle ear
• - Eustachian tubes

• -Larynx
• -Trachea
• -Bronchial tubes
• -Alveoli
• -Pleura 

-Suppress pathogens by competitive inhibition in upper respiratory system

-Lower respiratory system is sterile  

• -Pharyngitis
• -laryngitis
• -tonsillitis
• -sinusitis
• -epiglottitis   H.influenzae tybe b 

• -Also called strep throat
• -Streptococcus pyogens
• -resistant to phagocytosis
• -streptokinases lyse clots
•  -streptolysins are cytotoxic
• -Diagnosis by enzyme immunoassay (EIA) tests  

• Streptococcus pyogenes
• -pharyngitis
• -Erythrogenic toxin produced by lysogenized S. pyogenes

• -Corynebacterium diphtheriae: gram-positive rod
• -Diphtheria toxin produced by lysogenized C.diphtheriae

 

Fibrin, tissue, bacteria cells

• Preventd by DTap vaccine
•    -Diptheria toxoid

• Cutaneous diphtheria
•    -infected skin wounds leads to slow-helaing ulcer  

50%

15-20% 

• -Bronchitis
• -Bronchiolitis
• -Pnemonia 

• -Bordetella pertussis: gram-negative coccobacillus
• -Capsule
• -tracheal cytotoxin of cell wall damaged ciliated cells
• -pertussis toxin
• -prevented by DTaP vaccine (acellular pertussis cell fragments)  

Stage 1: Catarrhal stage, like common cold

Stage 2: Paroxysmal stage: violent couphing sieges

Stage 3: Convalescense stage 

• Mycobacterium tuberculosis
•      acid-fast rod: transmitted from human to human 

Less than 1% U.S. cases

not transmitted from human to human 

infects people with late-stage HIV infection

Treatment: prolonged  treatment with multiple antibiotics

Vaccines: BCG, live, avirulent M.bovis;   not widely used in the United States  

Tuberculin skin test screening

• -positive reaction means current or previous infection
• -followed by x-ray or CT exam, acid-fast staining of sputum, culturing of bacteria  

• Streptococcus pneumoniae
•   -gram-positive encapsulated diplococci 

Symptoms: infected alveoli of lung fill with fluids; interferes with oxygen uptake

Diagnosis: Optochin-inhibition test or bile solubility test, serological typing of bacteria

Treatment: penicillin, fluoroquinolones

Prevention: Pneomococcal vaccine 

• -Gram-negative coccobacillus
• -predisposing factors: alcoholism, poor nutrition, cancer, or diabetes
• -Symptoms: Resemble those of pneumococcal pneumonia
• -Diagnosis: Isolation, special media for nutritonal requirements

-Treatment: cephalosporins  

-Primary atypical pneumonia; walking pneumonia

-Mycoplasma pneumoniae; pleomorphic wall-less bacteria

-Common in children and young adults 

Symptoms: mild but persistent respiratory symptoms; low fever, cough, headache

Diagnosis: PCR and serological testing

Treatment: Tetracyclines  

-Legionella pneumophila: gram-negative rod

• -found in water
• -transmitted by inhaling aerosols; not transmitted from human to human 

Symptoms: potentially fatal pneumonia that tends to affect older men who drink or smoke heavily

Diagnosis: Culture on selective media, DNA probe

Treatment: Erythromycin  

-Chlamydophila pneumoniae

-transmitted from human to human 

Symptoms: Mild respiratory illness common in young people; resembles mycoplasmal pneumonia

Diagnosis: serological tests

• Treatment: tetracyclines
•  

Causative agent: Coxiella burnetii

• Reservoir: Large mammals
• -Tick vector
• -can be transmitted via unpasteurized milk 

Symptoms: Mild respiratory disease lasting 1-2 weeks; occasional complications such as endocarditis occur

Diagnosis: Growth in cell culture

Treatment: Doxycycline and Chloroquine 

Viral Pneumonia: occurs as a complication of influenza, measles, or chickenpox

Viral etiology suspected if no other cause is determined 

• Common in infants; 4500 deaths annually
• -causes cell fusion (syncytium) in cell culture
• -Symptoms: pneumonia in infants
• -Diagnosis: serological test for viruses and antibodiess
• -treatment: Ribavirin, palivizumab 

• Symptoms: chills, fever, headache, and muscle aches
•      -NO INTESTINAL SYMPTOMS

-1% mortality, very young and very old

-Treatment: Zanamivir and oseltamivir inhibit neuraminidase

Prophylaxis: multivalent vaccine 

Causative agent: Pneumocystis jirovecii

Reservoir: unknown, possibly humans or soi

Symptoms: pneumonia

Diagnosis: Microscopy

treatment: Trimethoprim  

• -Systemic
• -prediposing factors:
•      :immunocompromised state
•      :cancer
•      :diabetes
• -Aspergillus fumigatus
• -Mucor
• -Rhizopus 

Hemagglutinin (HA) spikes used for attachment to host cells 

Neuraminidase (NA) spikes used to release virus from cell 

• -Changes in HA and NA spikes
• -probably due to genetic recombination between differernt strains infecting the same cell  

• -Point mutations in genes encoding HA or NA spikes
• -May involve only 1 amino acid
• -Allows virus to avoid mucosal IfA antibodies  

-Histoplasma capsulatum, dimorphic fungus, flu like symptoms