Common Causes of Infectious Diseases by organ.

Central Nervous System Infections

 Neonates(less than 1 month old)

• Streptococcus agalactiae (Group b streptococcus)
• Escherichia col

Children and adults

• Streptococcus pneumoniae
• Neisseria meningitidis

Elderly (>60 yrs old)

• Streptococcus pneumoniae
• Gram negative bacilli

Viral (aseptic) meningitis and encephalitis (90% of cases in patients under 30 years old)

• Enteroviruses (70%; late summer and early fall)
• Arboviral meningoencephalitis (summer via tick or mosquito; West Nile virus, Eastern Equine Encephalitis virus, Western Equine Encephalitis virus, St. Louis Encephalitis virus, California group Encephalitis viruses, Powassan Encephalitis virus)- are the most common cause of episodic encephalitis in the US.
• Mumps (late winter and early spring)
• Herpes simplex virus (sporadic)
• HIV (sporadic)
• Rabies virus (rare)

Granulomatous Meningitis (Chronic meningitis)

• Mycobacterium tuberculosis
• Cryptococcus neoformans

Spinal cord

• Clostridium tetanus*
• Polio virus

Skin (Integument) Infections

There are a huge number of infectious diseases of this the largest organ of the human anatomy. Therefore, only the more common bacterial, viral and fungal microbes are mentioned here.

Common Bacterial Infections.

• Staphylococcus aureus - impetigo, bullous impetigo, scalded skin syndrome, folliculitis, furuncles, carbuncles, cellulitis, myositis and toxic shock syndrome.
• Streptococcus pyogenes - impetigo, scarlet fever, erysipelas, necrotizing fasciitis, and streptococcal toxic shock syndrome. 
• Propionibacterium acne - acne

Common Viral Infections.

• Herpes Simplex 1 and 2 viruses- oral and genital herpes
• Papilloma viruses – warts, genital warts, cervical dysplasia and cervical carcinoma
• Common childhood rashes (exanthems) are caused by
  • Coxsackie viruses and Echoviruses (enteroviral rashes),
  • Erythrovirus B19 (formerly Parvovirus B19; Erythema Infectiosum)
  • Human Herpes virus 6B (Exanthem subitum or Roseola)
  • Human Herpes Virus-7 (Exanthem subitum or Roseola)
  • Varicella-Zoster virus (Chickenpox)
  • Measles virus (Rubeola)
  • Rubella virus (Rubella).

Common Fungal Infections.

• Malassezia furfur- Tinea versicolor
• The dermatophytes (Microsporum,Trichophyton and Epidermophyton) - Tinea pedis, Tinea corporis, Tinea capitis, Tinea manus and Tinea cruris.
• Candida albicans - intertrigo, perlèche, folliculitis, paronchyia and onychomycosis.

Ear Infections
Otitis Media

• Streptococcus pneumoniae
• Moraxella catarrhalis
• Haemophilus influenzae (nontypable)

Otitis externa

• Pseudomonas aeruginosa*
• Staphylococcus aureus