Respiratory and AFB

Most common bacterial causes of otitis media

"Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis"

Moraxella catarrhalis hallmark colony feature

'Hockey puck' sign; colony slides across agar

Moraxella catarrhalis biochemical test

Butyrate positive

HACEK organisms

"Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella"

Most common causes of acute maxillary sinusitis

"S. pneumoniae, H. influenzae, Moraxella catarrhalis, viruses"

Hallmark bacterial cause of pharyngitis

Streptococcus pyogenes (Group A Strep)

Most acute pharyngitis cases are caused by?

Viruses (>90%)

Common viral causes of pharyngitis

"Rhinovirus, adenovirus, influenza, parainfluenza, RSV, coronavirus"

Scarlet fever is caused by?

GAS pyrogenic exotoxins (SpeA)

Scarlet fever findings

Strawberry tongue and sandpaper-like rash

Major sequelae of untreated GAS

Rheumatic fever and acute glomerulonephritis

GAS Gram stain morphology

Gram-positive cocci in chains/pairs

GAS hemolysis

Beta-hemolytic

Rapid GAS test performance

"High specificity, lower sensitivity"

Children with negative RADT should have?

Confirmatory throat culture

Why is routine GAS susceptibility testing not needed?

GAS remains susceptible to penicillin

Alternative antibiotic in severe penicillin allergy

Clindamycin

What test detects inducible clindamycin resistance?

D-zone test

Group C and G streptococci can cause?

Pharyngitis and poststreptococcal glomerulonephritis

Arcanobacterium haemolyticum age group

Teenagers and young adults

Arcanobacterium CAMP reaction

Reverse CAMP positive

Neisseria gonorrhoeae pharyngitis diagnosis

NAAT preferred

Lemierre syndrome organism

Fusobacterium necrophorum

Lemierre syndrome definition

Septic thrombophlebitis of the internal jugular vein after pharyngitis

Fusobacterium morphology

Fusiform anaerobic Gram-negative rods

Hallmark sign of diphtheria

Pseudomembrane

Diphtheria medium #1

Loeffler agar

Diphtheria medium #2

Potassium tellurite agar

Diphtheria toxin confirmation

Elek test

Bordetella pertussis disease

Whooping cough

Preferred Bordetella pertussis test

PCR

Bordetella culture medium

Regan-Lowe agar

Bordetella colony appearance

Mercury-drop colonies

Most common cause of bronchiolitis

RSV

Community-acquired pneumonia (CAP) definition

Pneumonia acquired outside the hospital

Hospital-acquired pneumonia (HAP) definition

Pneumonia ‚48 h after admission

Ventilator-associated pneumonia (VAP) definition

Pneumonia ‚48 h after intubation

Most common bacterial cause of CAP

Streptococcus pneumoniae

Typical CAP pathogens

"S. pneumoniae, H. influenzae, Moraxella, S. aureus, Klebsiella, E. coli"

Atypical CAP pathogens

"Mycoplasma, Legionella, Chlamydia pneumoniae"

Walking pneumonia organism

Mycoplasma pneumoniae

Mycoplasma key characteristic

Lacks a cell wall

Legionella source

Contaminated water systems

Legionella diagnostic test

Urine antigen test

Legionella culture medium

BCYE agar

Chlamydia psittaci exposure

Bird droppings (parrot fever)

Coxiella burnetii disease

Q fever

Most common AIDS-defining pneumonia

Pneumocystis jirovecii pneumonia

Pneumocystis diagnosis

Direct fluorescent antibody (DFA)

Good sputum specimen criterion

<10 squamous epithelial cells/LPF

Poor sputum specimens should be rejected except when?

AFB or Nocardia culture requested

BAL stands for?

Bronchoalveolar lavage

Protected brush specimen advantage

Minimizes upper airway contamination

Semiquantitative culture significance

Moderate (3+) or heavy (4+) growth

Quantitative culture purpose

Differentiate colonization from infection via CFU/mL

Mycobacterial cell wall component

Mycolic acids

Why are mycobacteria acid-fast?

Mycolic acid-rich waxy cell wall resists decolorization

Gram stain appearance of mycobacteria

Faintly staining/beaded Gram-positive rods

Two classic acid-fast stains

Ziehl-Neelsen and Kinyoun

Modified acid-fast stain organisms

"Nocardia, Gordonia, Tsukamurella"

Fluorescent AFB stain

Auramine-rhodamine or Auramine-O

Runyon Group I

Slow-growing photochromogens

Runyon Group II

Slow-growing scotochromogens

Runyon Group III

Slow-growing nonchromogens

Runyon Group IV

Rapid growers

Photochromogen example

Mycobacterium marinum

Scotochromogen example

Mycobacterium gordonae

Nonchromogen example

Mycobacterium avium complex

Rapid grower example

Mycobacterium abscessus or M. fortuitum

AFB respiratory specimen collection

3 first-morning sputum specimens

AFB specimen decontamination method

NALC-NaOH

AFB broth incubation duration

6 weeks

AFB solid media incubation duration

6-8 weeks

Common solid AFB media

Middlebrook 7H10/7H11 and Lowenstein-Jensen

M. tuberculosis colony appearance

"Rough, buff colonies with cording"

Pyrazinamidase test result for M. tuberculosis

Positive

Niacin test result for M. tuberculosis

Positive

Nitrate reduction test result for M. tuberculosis

Positive

Latent TB

Contained infection; not infectious

IGRA stands for

Interferon-gamma release assay

MDR-TB definition

Resistant to isoniazid and rifampin

MAC stands for

Mycobacterium avium complex

M. kansasii Runyon class

Photochromogen

M. marinum exposure

Aquariums/fish tanks or saltwater exposure

M. ulcerans disease

Buruli ulcer

M. leprae disease

Leprosy (Hansen disease)

M. leprae culture characteristic

Cannot be cultured in vitro