Cases in Medical Microbiology and Infectious Diseases. Melissa B. Miller
especially those in whom the duration of neutropenia is prolonged, not only have a risk of infection with routine bacteria but have a very high risk of invasive aspergillosis and other invasive fungal infections.
TABLE II SELECTED RESPIRATORY TRACT PATHOGENS
| ORGANISM | GENERAL CHARACTERISTICS | PATIENT POPULATION | DISEASE MANIFESTATION |
| Bacteria | |||
| Acinetobacter baumannii | Glucose-nonfermenting, Gram-negative bacillus | Hospitalized adults | Ventilator-associated pneumonia |
| Actinomyces spp. | Branching, Gram-positive bacilli, usually anaerobic | Adults with aspiration | Lung abscess |
| Bacillus anthracis | Spore-forming, Gram-positive bacillus | Victims of bioterrorism due to exposure to spores; woolsorters in endemic areas | Inhalation anthrax with widened mediastinum, high-grade bacteremia |
| Bordetella pertussis | Fastidious, Gram-negative bacillus | Children, adults | Whooping cough, chronic cough |
| Chlamydia trachomatis | Obligate intracellular bacterium; does not Gram stain | Neonatal | Conjunctivitis, pneumonia |
| Chlamydiophila pneumoniae | Obligate intracellular bacterium; does not Gram stain | Children, adults | Pneumonia, bronchitis |
| Chlamydiophila psittaci | Obligate intracellular bacterium; does not Gram stain | Children and adults with exposure to birds | Pneumonia, ornithosis (psittacosis) |
| Corynebacterium diphtheriae | Catalase-positive, Gram-positive, club-shaped bacillus | Unvaccinated adults and children, improperly vaccinated adults | Diphtheria |
| Enterobacter spp., Escherichia coli | Lactose-fermenting, Gram-negative bacilli | Hospitalized adults | Health care-associated pneumonia |
| Fusobacterium necrophorum | Anaerobic, Gram-negative bacillus | Adolescents, adults | Pharyngitis, Lemierre’s syndrome |
| Group A streptococci (Streptococcus pyogenes) | Catalase-negative, Gram-positive cocci in chains | Children >2 years, adults | Pharyngitis, pneumonia with empyema |
| Group B streptococci (Streptococcus agalactiae) | Catalase-negative, Gram-positive cocci in chains | Neonates | Pneumonia |
| Haemophilus influenzae | Pleomorphic, Gram-negative bacillus | Children; adults, especially with COPDa | Otitis media, conjunctivitis, epiglottitis, bronchitis, pneumonia |
| Klebsiella pneumoniae | Lactose-fermenting, Gram-negative bacillus | Adults | Community-acquired and health care-associated pneumonia |
| Legionella pneumophila | Poorly staining, fastidious, Gram-negative bacillus | Adults, especially immunocompromised | Pneumonia |
| Moraxella catarrhalis | Oxidase-positive, Gram-negative diplococcus | Children; adults with COPD | Otitis media, conjunctivitis, bronchitis |
| Mycobacterium tuberculosis | Acid-fast bacillus | Children and adults, especially HIV-infected | Tuberculosis |
| Mycoplasma pneumoniae | Fastidious; does not Gram stain | Children, adolescents, adults | Walking pneumonia |
| Neisseria gonorrhoeae | Oxidase-positive, Gram-negative diplococcus | Individuals with oral-genital contact, neonates | Pharyngitis, conjunctivitis |
| Neisseria meningitidis | Oxidase-positive, Gram-negative diplococcus | Adults | Pneumonia |
| Nocardia spp. | Partially acid-fast, aerobic, branching, Gram-positive bacilli | Adults, especially with defects in cell-mediated immunity | Pneumonia with brain abscess |
| Nontuberculous mycobacteria (many species) | Acid-fast bacilli | Adults with chronic lung disease, CFb patients | Granulomatous lung disease |
| Prevotella spp., Porphyromonas spp. | Anaerobic, Gram-negative bacilli | Adults with aspiration | Lung abscess |
| Pseudomonas aeruginosa | Glucose-nonfermenting, Gram-negative bacillus | Adults and children, diabetic adults, hospitalized patients, CF patients (mucoid variant) | External otitis (swimmer’s ear), malignant external otitis, ventilator-associated pneumonia, chronic bronchitis with mucoid strains |
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