Bacterial Respiratory Infections

Bacterial Pneumonia

• Streptococcus pneumoniae is the most common cause of bacterial pneumonia.
• Mycoplasma pneumoniae often causes atypical pneumonia.
• Klebsiella pneumoniae can cause a severe form of pneumonia, particularly in immunocompromised patients; this is known as nosocomial pneumonia
• "Walking pneumonia" is caused by Mycoplasma pneumoniae.

Whooping Cough

• Bordetella pertussis is the causative agent of whooping cough.

Tuberculosis

• Mycobacterium tuberculosis is the primary cause of tuberculosis; transmitted primarily through airborne droplets
• A patient with a persistent cough, blood-tinged sputum, and night sweats may have a Mycobacterium tuberculosis infection.

Diphtheria

• Corynebacterium diphtheriae infection presents with a grayish-white pseudomembrane in the throat.
• The toxin produced by Corynebacterium diphtheriae primarily affects the heart and nerves.

Lung Infections from Water Sources

• Legionella pneumophila is tied to bacterial lung infections from contaminated water sources.
• Legionella pneumophila causes Pontiac fever.

COPD Exacerbations

• Haemophilus influenzae is a common cause of acute exacerbations in COPD.

Syphilis

• Treponema pallidum causes syphilis.
• A painless ulcer (chancre) characterizes primary syphilis.
• A widespread rash, including on the palms and soles, characterizes secondary syphilis.

Gonorrhea

• Neisseria gonorrhoeae causes gonorrhea, it is a gram-negative diplococcus.
• Neisseria gonorrhoeae can cause a bacterial STI which may lead to pelvic inflammatory disease (PID).

STIs and Complications

• Haemophilus ducreyi causes a STI resulting in soft, painful genital ulcers (chancroid).
• Chlamydia trachomatis can cause a severe STI complication known as pelvic inflammatory disease (PID); associated with a "strawberry cervix".
• Fitz-Hugh-Curtis syndrome is most commonly caused by Chlamydia trachomatis; the most common bacterial STI worldwide is Chlamydia.

Bacterial Meningitis

• Streptococcus pneumoniae is the most common cause of bacterial meningitis in adults; Group B Streptococcus is the most likely cause of meningitis in newborns.
• Neisseria meningitidis is a gram-negative bacterium that commonly causes meningitis in college students.
• Listeria monocytogenes is a foodborne pathogen causing meningitis in neonates and immunocompromised individuals.
• Neisseria meningitidis is primarily transmitted via respiratory droplets.
• In bacterial meningitis, Kernig's sign involves pain on knee extension when the hip is flexed.

Preventable Blindness

• Chlamydia trachomatis is the leading cause of preventable blindness worldwide.

Eye Infections

• Neisseria gonorrhoeae causes ophthalmia neonatorum
• For contact lens wearers, Pseudomonas aeruginosa is a bacterial eye infection causing corneal ulceration.
• Staphylococcus aureus is the most common bacterial cause of blepharitis;causes conjunctivitis and a systemic infection in newborns; causes red eyes, purulent discharge, and eyelid swelling.
• Gonococcal keratitis is a bacterial infection of the eye that can rapidly progress to corneal perforation if left untreated.
• Neisseria gonorrhoeae can cause a neonatal eye infection, prevented by prophylactic erythromycin drops.
• Haemophilus influenzae is a common bacterial cause of orbital cellulitis.
• Herpes simplex virus is not a bacterial cause of keratitis.
• Practicing proper hand hygiene is the best way to prevent bacterial eye infections.

Other Bacterial Infections

• Klebsiella pneumoniae causes lung abscesses; associated with alcohol abuse.
• Streptococcus pyogenes causes scarlet fever, typically associated with pharyngitis.
• Clostridium tetani causes lockjaw (tetanus) through toxin production.
• Clostridium botulinum produces a toxin that leads to flaccid paralysis.
• Streptococcus pneumoniae is the most common bacterial cause of brain abscesses.