Skin Infections Flashcards
What are the microbial strategies to bypass skin defense ?
A) parenteral route
1- Break in skin ( cute and biting arthropods )
B) infecting hair follicles or sebaceous glands
( staphylococcus aureus which bind to accessory oranges and causes ( boils and abscesses )
What are the skin defense?
1)Stratified squamous epithelium- Tight junction b/t cell Keratinization for water proofing 2) normal flora :- Breaks down oils to fatty acids 3) lysozyme:- degrades peptidoglycan
Etiology of staphylococcus aureus ?
Gram positive ( staphylococcus)
Resistant to b- lactams ( penicillin)
Produce many toxin and tissue damaging enzymes
Causes Boils***
What causes Boils ( دمله) ?
Staphylococcus aureus
Gram positive
R to b-lactams ( pencillininc)
Produce many toxic and tissue damage enzymes
How does Boil ( staphylococcus aureus) transmitted and what kind of mode ?
Reservoir ( person or animal colonized with staphylococcus aureus, some chronically carry staphylococcus aureus in their nasal mucous)
Mode of transmission is contact mode ( direct or through fomites contact )
High solute called named as (—)? Which kills most of the bacteria expect staphylococcus aureus
Facultative Halophile
How does ( staphylococcus aureus) boil enter ? Attach ? Avoid ? Damage and exit ?
1-Enter- direct contact infected person or self inoculate (Nose reservoir )
2-Attach- to hair follicles
3-avoid- by Leukocidins ; coagulase ( white blood cells)
4- damage- inflammatory response
5- exist - By Rupture release pus
What is the signs and clinical symptoms of Boil ( staphylococcus aureus) ?
1- progressing edema at the site of infection ( coagulase form a blood clot ) 2- pain 3-redness 4-localized fever Inflammatory response (2-3-4) 5-pus 6- hard core
How you treat boil ( staphylococcus aureus) ?
Treatment choses are ( cloxacillin or Flucloxacillin )
You might use b-lactams that are not susceptible to B-lactamase
Used for MSSA ( methicillin-susceptible staphylococcus aureus not degraded by B-lactamase
Ampicillin binds to PBP ( penicillin-binding- protein ) which results on deactivate of PBP
What is PBP ?
Cell wall synthetase enzymes
How you prevent Boil ( staphylococcus aureus) ?
1-By treating chronic nasal carriers with antibiotics creams
2- good personal hygiene ( showers , washing hands)
Aureus mean =gold
Streptococcus pyogenes characters ?
- gram +
- Fermentation metabolism ( takes place on lack of Oxygen)
- B- hemolytic on blood agar
- group A protein on surface
- produces many tissues-damaging enzymes
Causes Cellulitis *****
What causes Cellulitis For immunocompent individual ( mean healthy person) ?
( most commonly staphylococcus aureus and group A strep ( streptococcus pyogenes )
What are these Predisposing Factors that causes Cellulitis ?
Diabetes
Immunodeficiency
Varicella
Impaired peripheral circulation
Lymphadenectomy following tumor excision , such as mastectomy
Postvenectomy status following vein stripping
Chronic steroids uses
How does Cellulitis ( streptococcus pyogenes) transmitted and what kind of mode ?
- reservoir ( symptomatic or asymptotic individuals ) :-( colonization with Staphylococcus aureus or streptococcus pyogenes is common )
- mode via contact mode ( direct or fomites contact)
What are the sign and clinical features of Cellulitis ? Uncomplicated
- Uncomplicated ( infection of the dermis and subcutaneous tissue resulting in ( Redness , edema, pain and local fever
What are the signs and clinical features of Cellulitis the potential complications?
1- potential complications:-
- May become a very serious illness by uncontrolled spread contiguous or VIA the Lymphatic or Circulatory system
- deep and rapidly spreading infection may develop into life -threatening emergencies
How does Cellulitis may be Diagnosed ? For Non- complicated
Normally specimen collection and lab tests are not done because non complicated Cellulitis in immunocompent individuals is Consistently caused by Strep and Staph and Is Treatable
How may Cellulitis diagnosed ? For immunocompent and complicated Cellulitis-
1) Specimen : Aspirate of Infected site
2) Test : Culture & Gram stain
How does Cellulitis treated?
Penicillinase -resistant synthetic Penicillin ( Diclixacillin ) or 1St generation Cephalosporins ( Cephazolin )
These antibiotics Will treat both Group A Streptococcu and MSSA (Methcillin-susceptible staphylococcus aureus)
** if allergic, Erythromycin is used as an alternative **
How does Cellulitis can be prevented?
1- educate pt regarding proper skin hygiene
2- wash , treat and cover cuts and skin abrasion
** patients with recurrent streptococcal Cellulitis may used Penicillin G Or Erythromycin
3- Support Stocking
Etiology of Pseudomonas aeruginosa ? very Common pathogens
Gram -
Monopolar Flagellum
Often Drug R
Resistant to Disinfectants
What are the Site of infection that Caused by Pseudomonas aeruginosa? Common Pathogens
1- Epidermis
2- Burns
3- Lungs ( purple Pus )
4- Nosocomial ( hospital ) UTIs ( urinary tract infections)
Etiology of Clostridium perfringens ? Uncommon Pathogens
-1-gram + , endospore -forming rod shape
2-obligate anaerobic ( they can grow with or without Oxygen)
( infect puncture wounds ,, wounds with poor blood supply)
- 3 Causes Gas Gangrene
