Skin and Eye Infections PDF

Skin and Soft Tissue Chapter 33  Introductio n Skin Epidermis – outermost layer Dermis hair follicles, sebaceous glands, sweat glands Subcutaneous layer (fat) Fascia (fibrous tissue) Muscles Introduction  Wound Infections...

Skin and Soft Tissue Chapter 33  Introductio n Skin Epidermis – outermost layer Dermis hair follicles, sebaceous glands, sweat glands Subcutaneous layer (fat) Fascia (fibrous tissue) Muscles Introduction  Wound Infections Causes result of trauma (minor or severe) obstruction of oil or sweat glands inflammation of hair follicles Infecting organisms may be Endogenous – normal flora (scrape) Exogenous – outside the body (bite, knife) Single or polymicrobial infections Skill needed to recognize and separate colony types in mixed culture  Normal Skin Flora Staphylococci (S. epidermidis & S. aureus) Diphtheroids (Corynebacterium) Micrococci Streptococci (non-hemolytic) Propionibacterium acnes Anaerobes Yeast  Dermatitis: Inflammation of the Skin Candidia spp. S. aureus Coliforms Corynebacterium spp. Moulds (Dermatophytes)  Pyroderma: Inflammation with Pus Impetigo blister-like superficial skin infection Group A streptococci S. aureus Erysipelas Superficial but painful Group A streptococci S. aureus (rarely) Anthrax  Pyroderma: Inflammation with Pus Erysipeloid Superficial soft skin infection Associated with animal/meat/hides Erysipelothrix rhusiopathiae Cellulitis – diffuse infection in deep epidermis tissue and subcutaneous tissues Group A streptococci S. aureus  S. aureus and MRSA Folliculitis - infected hair follicle Sometimes P. aeruginosa (contaminated hot tubs) Furuncles (boils) – located deep in hair follicles Carbuncles – involve multiple hair follicles Other Skin Infections Abscesses collection of pus in skin and subcutaneous tissue  Soft Tissue (Wound) Infections Injured tissue (surgery, burns, bites) caused by many organisms Surgical wound infections S. aureus Streptococci Anaerobes Burn wounds S. aureus P. aeruginosa  Soft Tissue Infections Animal Bites Pasteurella multocida Capnocytophaga canimorsus S. aureus Anaerobes Rabies Human bite S. aureus alpha strep Myonecrosis Gas gangrene Severe muscle infection C. perfringens Necrotizing Fasciitis Infection of fascia Very severe Group A strep S. aureus  Decubitus Ulcers Bed sores or pressure sores caused by bacteria near the rectum Enterobacteriaceae Pseudomonas Enterococci  Diabetic Foot Ulcers Injuries heal slowly S. aureus streptococci enterococci Enterobacteriaceae Pseudomonas aeruginosa anaerobes  Nodular Lymphangitis Sporothrix schenckii Nocardia spp. Actinomyces spp. Mycobacteria  Dermatologic Manifestations of Systemic Infections Borrelia burgdorferi (erythema migrans) Rashes T. pallidum Rickettsiae Leptospira Mycobacterium leprae  Dermatologic Manifestations of Systemic Infections Viruses Measles (Rubeola and Rubella) Chickenpox/Shingles (Varicella-Zoster Virus) Herpes Simplex Virus Warts (HPV) Parasites Later!  Toxin-Mediated Skin Diseases Staphylococcal scalded-skin syndrome Toxin shock syndrome S. aureus and S. pyogenes Scarlet fever S. pyogenes  Specimen Collection and Transport Avoid surface contamination Skin or mucous membrane decontaminated before collection Tissue and pus aspirates preferred specimens Tissue should be kept moist  Specimen Collection and Transport Swabs are least desirable Swabs placed in transport medium For anaerobic infection use anaerobic transport media  Microscopic Examination Gram stain some clinically significant organisms can be detected determine specimen quality reject if many epithelial cells seen, similar to sputum evaluation Wet mount with KOH and calcofluor white Acid-fast stain  Cultures BAP, CHOC, MAC, PEA Routine media vary with setting, site, organisms suspected 35 C in CO2 Anaerobic Culture Recommended for closed wounds and abscesses Should be cultured aerobically also Other Cultures Lowenstein-Jensen, Middlebrook Viral culture, shell vials Sabouraud’s agar  Other Cultures Eye, Bone, BM, External Ear  Eye Cultures NF of mucous membrane covering eyeball and eyelids Corynebacterium Viridans strep Moraxella catarrhalis staphylococci (S. aureus and CoNS) Haemophlius influenzae anaerobes GNR  Diseases Conjunctivitis-inflammation of conjunctiva Eye drops in newborns prevent neisserial and chlamydial infection Haemophilus influenzae aegyptius, S. pneumoniae Keratitis- inflammation of cornea usually due to trauma, various organisms Endophthalmitis - rare inflammation of eyeball’s interior Specimens Conjunctival specimens collected with swab Corneal scraping by special platinum spatula inoculated at bedside Eye chamber fluid for endophthalmitis Processing Microscopic Examination of gram stain Cultures BAP, CHOC, enriched broth, MAC anaBAP in some situations (endophthalmitis) Osteomyelitis Infection of bone or bone marrow S. aureus (most common) Bone Cultures Placed in enriched broth Pieces inoculated onto agar media (CHOC) Bone Marrow Only in special situations detection of Brucella or Mycobacteria Media depends on organism sought External Ear Otitis externa - swimmer’s ear due to moisture in ear canal Malignant otitis externa severe invasive infection underlying conditions (diabetes) P. aeruginosa (most common) External Ear Cultures Diagnosed clinically Culture recommended for malignant and recurrent cases Debris removed from ear canal Collected with swab Gram stain Cultured on BAP, CHOC, MAC Agents of Bioterror 1  Bioterrorism The unlawful use, or threatened use, of microorganisms or toxins derived from living organisms to produce death or disease in humans, animals, or plants. The act is intended to create fear and intimidate governments or societies in the pursuit of political, religious, or ideological goals. 2 Types Overt Immediate impact Early recognition of event Covert Delayed response Recognized clinically 3  History 600 BC: rye ergot, produces a hallucinogen similar in chemistry and effects to LSD. WWI: Bacillus anthracis and Pseudomonas mallei (livestock) 1984: Oregon Salmonella (restaurant) 2001: New York & Florida, B. anthracis 4 Characteristics of Bioterror Agents Inexpensive / relatively easy to produce Cost: (1970 Study - Cost of 50% casualties over a 1sq/km area) Conventional weapons - $2,000 Nuclear - $800 Chemical - $600 Anthrax - $1 5  More Characteristics Threat alone may create panic Large attack areas may be covered Detection may be difficult: Odorless, Colorless, Tasteless First Sign of Attack is Human Illness Some pathogens are contagious Perpetrators may protect themselves and escape before effects are felt 6  Common Characteristics Can be a liquid or powder Successfully dispersed as aerosols when particle sizes are 1 to 5 microns Weather is a key factor May also be delivered orally through food or water contamination 7  Biological Delivery Methods Food / Water Air handling Aircraft sprayers systems Vehicle sprayers Human Vector Hand sprayers Animal Vector Mail 8  Laboratory Response Ne LRN Established by CDC in 1999 Network of labs that respond to biological and chemical public health threats Test according to consensus protocols Timely and accurate testing and reporting Linked with Local, State and Federal Agencies 9  LRN Laboratory Levels Sentinel Labs Clinical Labs (BSL2) Recognize, Rule out, Refer Reference Labs Public Health and Typing Labs Confirmatory testing National Labs CDC (BSL4), Military Bioforensics Definitive characterization 10  Potential Bioterrorism A Potentially thousands Respiratory Aerosolized agents Person-to-person spread Gastrointestinal Skin and mucous membranes CDC created Category A, B, & C Based on: Ease of dissemination Potential for Public Health Impact Potential for Public Panic and Social Disruption 11  Biological Agent Catego Category A Example: Yersinia pestis Spread person to person May cause panic and social disruption High mortality Require special action to insure preparedness 12  Biological Agent Catego Category B Example: E. coli 0157:H7 Moderately easy to spread Moderate illness rate, low death rate Require enhancement of CDC lab capacity 13 Biological Agent Catego 14 Category C 15  Anthrax Bacillus anthracis Bacillus anthracis Gram-positive, spore-forming bacillus 16  Anthrax Bacillus anthracis Three forms of human anthrax occur: Cutaneous Gastrointestinal Oropharyngeal Abdominal Inhalation 17  Anthrax Bacillus anthracis Cutaneous Exposure- Most common A skin lesion evolving during a period of 2 - 6 days from a papule, through a vesicular stage, to a depressed black eschar 18 Anthrax Lesion on Neck 19 Cutaneous Anthrax 20 Intense itching  Gastrointestinal Anthrax Ingestion of spores Incubation: 2 - 5 days Nausea and vomiting bloody diarrhea & spesis Mortality: 50% 21  Inhalation Anthrax Inhalation Anthrax 5,000 – 8,000 spores A brief prodrome resembling a viral respiratory illness Radiograph evidence of mediastinal widening 22  Inhalation Anthrax Flu-like symptoms – Fever, fatigue, muscle aches, difficulty breathing, headache, chest pain & non-productive cough 1 - 2 day improvement followed by respiratory failure, meningitis may develop No person-to-person spread 23  Anthrax Specimens Inhalational Cutaneous Sputum Vesicles Blood Eschars Swabs Gastrointestinal Environmental Blood Powder Stool Evidentiary 24  Lab Identification Gram stain GPR (spores) Aerobic growth Nonhemolytic, ground glass colonies Medusa-head Catalase positive, nonmotile 25  Plague Yersinia pestis Black Death Distribution Highest in 4 corners area – Western states Prairie dog, deer mice, ground squirrels 26  Plague Yersinia pestis Transmission Inhalation Direct contact Fleas 27  Plague Clinical presentations Bubonic Infected lymph nodes Septicemic Blood-borne organisms Necrotic changes (Black Death) Pneumonic Transmissible by aerosol; deadliest 28  Plague Bubonic Septicemic Flu-like with Similar to bubonic painful No swelling of buboes lymph nodes (lymph nodes) 29  Plague Pneumonic Highest mortality Rapid transmission Fever Hemoptosis Lymphadenopathy Cough 30  Plague Specimen Collect Specimen selection Pneumonic is Important!! Sputum Bronchial Bubonic washings/tracheal Bubo aspirate Lymph node aspirate Environmental Septicemic Fleas Blood Powder 31  Lab Identification GNR Safety-pin appearance sometimes Slow growth (~2 days) SBA: Nonhemolytic, fried egg colonies MAC: small NLF Nonmotile Oxidase, urea, indole negative 32  Tularemia Francisella tularensis Zoonotic Infection Rabbit - Tick Plague-like disease in rodents (California) Deer-fly fever (Utah) Glandular tick fever (Idaho and Montana) Market men’s disease (Washington, DC) Rabbit fever (Central States) O’Hara’s disease (Japan) Water-rat trappers disease (Russia) 33  Tularemia NO person-to-person transmission Infective dose 10 - 50 organisms Incubation period 1 - 21 days (avg. 3 - 5) Duration of Illness ~ 2 weeks 34  Tularemia Mortality low (treated), moderate (untreated) Persistence of organism months in moist soil Vaccine efficacy is good, ~80% 35  Tularemia Clinical Presentations Pneumonic Glandular Incubation 3 - 5 days Adenopathy w/o lesion Flu-like symptoms Mortality – Ulceroglandular 30% untreated Ulcer w/adenopathy 6 months Duration of illness weeks to months 40  Brucellosis Brucella species Fever, profuse sweating, malaise, headache and muscle/back pain. NO Person to person transmission Mortality =