Skin and Soft Tissue Infections PDF

Skin and Soft Tissue Chapter 33 Introduction 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 (min...

Skin and Soft Tissue Chapter 33 Introduction 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 Respiratory Tract Chapter 32 Introduction URT – infections of the oral cavity and neck nose, mouth, throat, epiglottis, larynx contains NF middle ear and paranasal sinuses connected LRT trachea, bronchi, bronchioles, lung alveoli below larynx is normally sterile Respiratory Tract  Normal Flora of URT Staphylococci Diphtheroids CoNS Neisseria spp. S. aureus Haemophilus Streptococci Anaerobes viridans Spirochetes pneumococci Candida spp. Micrococcus spp.  Infections of the URT Thrush Sinusitis Laryngitis Otitis media Epiglottitis Diphtheria Phayngitis Pertussis (Whooping Tonsillitis cough) URT Pathogens Respiratory viruses Influenza, parainfluenza, RSV, adenovirus, rhinovirus, coronavirus, coxsackie A, EBV, CMV S. pyogenes ß-hemolytic strep group C, F and G Arcanobacterium haemolyticum URT Pathogens H. influenzae and parainfluenzae N. gonorrhoeae Corynebacterium diphtheriae Bordetella pertussis and parapertussis Yeast URT Specimen Collection Specimens Swab Syringe and needle Biopsy Diphtheria (C. diphtheriae) cultured on BAP, Loeffler, tellurite media Pertussis (Bordetella pertussis) cultured on Bordet-Gengou blood agar Specimen Collection Posterior pharynx and tonsils swabbed Placed in transport media Most labs seek only group A strep antigen testing performed first, enough if positive (high specificity, low sensitivity) If negative, some labs set up strep confirmation culture Microscopic Examination Gram stain not appropriate not diagnostic Lots of NF Cultures Mainly for group A strep Other organisms may be sought in certain situations upon request groups B, C, F, G N. gonorrhoeae Arcanobacterium haemolyticum C. diphtheriae Throat Culture Epiglottitis 2-6 years of age H. influenzae type b (almost exclusive) Life threatening disease airways can become obstructed Becoming rare due to Hib vaccine Diagnosed clinically Epiglottal specimen collection is hazardous Blood cultures performed (bacteremia) Sinusitis Preceded by a viral URTI Acute sinusitis S. pneumoniae, H. influenzae others: M. catarrhalis, group A strep, anaerobes, S. aureus, GNR Chronic sinusitis anaerobes, S. aureus in adults S. pneumoniae, S. aureus, viridans streptococci in children Specimen Collection Diagnosed clinically or radiographically Collected when patient not responding to therapy Sinus aspirate or sinus opening (sinus ostium) Collected in anaerobic transport medium Specimen Collection Processing Sinus Aspirate Gram stain and culture aerobically and anaerobically BAP, CHOC, MAC, anaBAP Identification and susceptibility performed Sinusitis Otitis Media Middle ear infection Children 25 epithelial/LPF Under oil immersion, record quantity (rare, moderate, many) and type of bacteria Unacceptable Gram Stain LPF HPF Acceptable Gram Stain Routine Cultures For sputum, tracheal aspirates, bronchial washings, bronchial brushings, bronchial biopsies BAP, CHOC, MAC Incubated at 35 C in CO2 For Cystic Fibrosis patients special media for B. cepacia, MRSA, and Pseudomonas Anaerobic Cultures Lung aspirates (Pleural Fluid) and open- lung biopsies Only specimens collected in a way that bypasses oral cavity are cultured anaerobically Work-Up Depends on type and quality of specimen Gram stain evaluation very important 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 Characteristic ◼ 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 N 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 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  Gastrointestinal Anthra ◼ 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 buboes ◼ No swelling of (lymph nodes) lymph nodes 29  Plague ◼ Pneumonic ◼ Highest mortality ◼ Rapid transmission ◼ Fever ◼ Hemoptosis ◼ Lymphadenopathy ◼ Cough 30  Plague Specimen Colle ◼ 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 =