Bacterial skin infections

Bacteria such as some Staphylococcus species, Corynebacterium spp., Brevibacterium spp and Acinetobacter live on normal skin and cause no harm. Propionibacteria live in the hair follicles of adult skin and contribute to acne.

Some bacteria invade normal skin, broken skin from eczema/dermatitis or wounds (causing wound infection). Bacteria, like viruses, may also sometimes result in exanthems (rashes). The most common bacteria to cause skin infections are:

• Staphylococcus aureus
  • Folliculitis
  • Furunculosis (boils)
  • Impetigo (school sores)
  • Methicillin (meticillin) resistant Staph. aureus
  • Staphylococcal scalded skin syndrome
  • Toxic shock syndrome
  • Tropical pyomyositis
  • Botryomycosis (pyoderma vegetans)
• Streptococcus pyogenes
  • Cellulitis
  • Erysipelas
  • Impetigo
  • Necrotising fasciitis
  • Scarlet fever
  • Rheumatic fever, erythema marginatum
• Overgrowth of Corynebacterium spp. (erythrasma, pitted keratolysis & trichomycosis axillaris)

Less commonly, other bacteria may also cause infection with skin signs. These include:

• Neisseria species, cause of gonorrhoea and meningococcal disease
• Erysipelothrix insidiosa, cause of erysipeloid (usually an animal infection)
• Haemophilus species, cause of chancroid and cellulitis in young children
• Helicobacter pylori, a stomach infection, which may be associated with some cases of chronic urticaria and rosacea
• Klebsiella rhinoscleromatis, cause of rhinoscleroma
• Mycoplasma pneumoniae, a cause of pneumonia, causes non-specific erythema, bullous eruptions, urticarial rashes, erythema multiforme, mucositis and rarely, SJS/TEN
• Pseudomonas aeruginosa causes wound infections, athlete's foot, gram negative folliculitis, chronic paronychia, spa pool folliculitis and ecthyma gangrenosum
• Calymmatobacterium granulomatis, cause of granuloma inguinale
• Bacillus anthracis, cause of anthrax
• Clostridium perfringens and other species cause gas gangrene
• Treponema species cause syphilis, yaws and pinta
• Bartonella species cause cat scratch fever, bacillary angiomatosis and bartonellosis
• Mycobacterium species cause tuberculosis, leprosy and atypical mycobacterial infections including Buruli ulcer
• Leptospira, cause of leptospirosis, which may cause bleeding into the skin (purpura)
• Nocardia, cause of nocardiosis
• Yersinia pestis, cause of bubonic plague, which causes swollen lymph glands and pustules, ulcers and scabs on the skin
• Serratia marcescens, a facultative anaerobic gram-negative bacillus that may rarely cause skin infections such as cellulitis, abscesses and ulcers; usually in patients with immunodeficiency.
• Fusibacterium species, Bacillus fusiformis, Treponema vincenti and other bacteria may result in tropical ulcer
• Burkholderia species, cause of melioidosis and glanders, in which abscesses may be associated with systemic symptoms.
• Actinomcyes species, cause of actinomycosis, in which granular bacteriosis occurs i.e. abscesses and sinus tracts draining sulphur-yellow granules.
• Vibrio vulnificus, a cause of septic shock characterised by blood-filled blisters.
• Brucella species, cause of brucellosis, a febrile illness caught from unvaccinated animals or their unpasteurised milk.

Tick-borne bacterial infections include:

• Lyme disease, due to Borrelia burgdorferi
• Relapsing fever, due to Babesia microti
• Tularaemia, due to Francisella tularensis
• Rickettsial diseases.

Other conditions sometimes caused by bacterial infection include:

• Kawasaki disease (mucocutaneous lymph node syndrome)
• Pseudofolliculitis barbae (shaving bumps)
• Sarcoidosis
• Scalp folliculitis
• Osler nodes and Janeway lesions (bacterial endocarditis)
• Vaginitis