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Questions and Answers
Which of the following infections is primarily associated with animal exposure?
Which of the following infections is primarily associated with animal exposure?
Which additional organism is commonly related to contaminated hot tubs in folliculitis cases?
Which additional organism is commonly related to contaminated hot tubs in folliculitis cases?
What type of infection is characterized by a diffuse infection in deep epidermis tissue and subcutaneous tissues?
What type of infection is characterized by a diffuse infection in deep epidermis tissue and subcutaneous tissues?
Which of the following is a key bacterial cause of necrotizing fasciitis?
Which of the following is a key bacterial cause of necrotizing fasciitis?
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Which type of infection could result from surgical wounds and commonly involves S.aureus?
Which type of infection could result from surgical wounds and commonly involves S.aureus?
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Which bacteria is primarily responsible for gas gangrene, a severe muscle infection?
Which bacteria is primarily responsible for gas gangrene, a severe muscle infection?
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Which of the following organisms are considered normal flora of the skin?
Which of the following organisms are considered normal flora of the skin?
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What is the correct term for inflammation associated with pus formation in the skin?
What is the correct term for inflammation associated with pus formation in the skin?
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What is the most common microorganism associated with osteomyelitis?
What is the most common microorganism associated with osteomyelitis?
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Which specimen collection technique is used for corneal scraping in cases of keratitis?
Which specimen collection technique is used for corneal scraping in cases of keratitis?
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In the context of external ear infections, what is commonly referred to as swimmer's ear?
In the context of external ear infections, what is commonly referred to as swimmer's ear?
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What type of bioterrorism event involves an immediate impact and early recognition of an event?
What type of bioterrorism event involves an immediate impact and early recognition of an event?
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What culture media is commonly used for the diagnosis of malignant otitis externa?
What culture media is commonly used for the diagnosis of malignant otitis externa?
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What form of bioterrorism relates to the use of microorganisms for fear rather than immediate physical harm?
What form of bioterrorism relates to the use of microorganisms for fear rather than immediate physical harm?
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Which organism is the most commonly associated risk factor for malignant otitis externa?
Which organism is the most commonly associated risk factor for malignant otitis externa?
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Which specimen is collected specifically for detecting endophthalmitis?
Which specimen is collected specifically for detecting endophthalmitis?
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What is the primary characteristic of Brucella species in terms of transmission?
What is the primary characteristic of Brucella species in terms of transmission?
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Which organism is primarily associated with causing diabetic foot ulcers?
Which organism is primarily associated with causing diabetic foot ulcers?
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Which of the following symptoms is NOT associated with Tularemia?
Which of the following symptoms is NOT associated with Tularemia?
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Which of the following organisms is most commonly involved in the formation of decubitus ulcers?
Which of the following organisms is most commonly involved in the formation of decubitus ulcers?
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What is the typical incubation period for Tularemia?
What is the typical incubation period for Tularemia?
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Which method of specimen collection is least desirable for anaerobic infections?
Which method of specimen collection is least desirable for anaerobic infections?
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Which laboratory identification feature characterizes the organism causing Tularemia?
Which laboratory identification feature characterizes the organism causing Tularemia?
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What is the approximate mortality rate of untreated Tularemia?
What is the approximate mortality rate of untreated Tularemia?
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Which of the following stains can determine the quality of a specimen?
Which of the following stains can determine the quality of a specimen?
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What is the characteristic colony appearance of Tularemia on sheep blood agar?
What is the characteristic colony appearance of Tularemia on sheep blood agar?
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What is the preferred culture medium for anaerobic cultures?
What is the preferred culture medium for anaerobic cultures?
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Which organism is associated with scalded skin syndrome?
Which organism is associated with scalded skin syndrome?
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What is the role of fleas in relation to the Bubonic plague?
What is the role of fleas in relation to the Bubonic plague?
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What is the average duration of illness for untreated Tularemia?
What is the average duration of illness for untreated Tularemia?
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Which of the following is a common manifestation of systemic infections in dermatology?
Which of the following is a common manifestation of systemic infections in dermatology?
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What should be done to tissue before collection for optimal specimen quality?
What should be done to tissue before collection for optimal specimen quality?
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What is the reported cost of causing 50% casualties over a 1 sq/km area using anthrax?
What is the reported cost of causing 50% casualties over a 1 sq/km area using anthrax?
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Which of the following characteristics is NOT associated with anthrax as a bioterror agent?
Which of the following characteristics is NOT associated with anthrax as a bioterror agent?
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Which of the following statements is true regarding the delivery methods for biological agents?
Which of the following statements is true regarding the delivery methods for biological agents?
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In the context of bioterrorism, what is the main reason for classifying agents into Categories A, B, and C?
In the context of bioterrorism, what is the main reason for classifying agents into Categories A, B, and C?
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Which level of the Laboratory Response Network (LRN) is responsible for confirmatory testing?
Which level of the Laboratory Response Network (LRN) is responsible for confirmatory testing?
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What is a significant factor that affects the dispersion of biological agents like anthrax?
What is a significant factor that affects the dispersion of biological agents like anthrax?
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Which biological agent is listed as Category A due to its potential for high mortality and social disruption?
Which biological agent is listed as Category A due to its potential for high mortality and social disruption?
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What type of laboratory is categorized as BSL4 and is involved in bioforensics?
What type of laboratory is categorized as BSL4 and is involved in bioforensics?
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What is a common initial indication of a bioterrorism attack involving biological agents?
What is a common initial indication of a bioterrorism attack involving biological agents?
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Which delivery method is NOT typically associated with anthrax dissemination?
Which delivery method is NOT typically associated with anthrax dissemination?
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What is the mortality rate associated with gastrointestinal anthrax?
What is the mortality rate associated with gastrointestinal anthrax?
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Which form of anthrax is characterized by a skin lesion evolving into a black eschar?
Which form of anthrax is characterized by a skin lesion evolving into a black eschar?
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What is the primary method of transmission for Yersinia pestis in its pneumonic form?
What is the primary method of transmission for Yersinia pestis in its pneumonic form?
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What laboratory identification technique can indicate the presence of Bacillus anthracis?
What laboratory identification technique can indicate the presence of Bacillus anthracis?
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Which symptom is NOT typically associated with inhalational anthrax?
Which symptom is NOT typically associated with inhalational anthrax?
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Which type of anthrax has the highest mortality rate and is characterized by respiratory symptoms?
Which type of anthrax has the highest mortality rate and is characterized by respiratory symptoms?
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What is the primary vector for the transmission of plague?
What is the primary vector for the transmission of plague?
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Which of the following specimens is NOT typically used for diagnosing inhalation anthrax?
Which of the following specimens is NOT typically used for diagnosing inhalation anthrax?
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What is the incubation period for gastrointestinal anthrax after ingestion of spores?
What is the incubation period for gastrointestinal anthrax after ingestion of spores?
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What type of anthrax is characterized by flu-like symptoms followed by severe respiratory failure?
What type of anthrax is characterized by flu-like symptoms followed by severe respiratory failure?
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Study Notes
Skin and Soft Tissue
- Skin is composed of epidermis (outermost layer), dermis (containing hair follicles, sebaceous and sweat glands), subcutaneous layer (fat), fascia (fibrous tissue), and muscles.
- Wound infections can be caused by trauma, obstruction of glands, or inflammation of hair follicles.
- Infecting organisms can be endogenous (normal flora) or exogenous (outside the body).
- Skill is needed to distinguish different colony types in mixed cultures.
- Common skin flora includes staphylococci (S. epidermidis & S. aureus), diphtheroids (Corynebacterium), micrococci, streptococci (non-hemolytic), propionibacterium acnes, anaerobes, and yeast.
- Dermatitis is skin inflammation caused by Candida spp., S. aureus, coliforms, Corynebacterium spp., and moulds (dermatophytes).
- Pyoderma is inflammation with pus, including Impetigo (blister-like superficial skin infection caused by Group A strep and S. aureus), Erysipelas (superficial but painful infection caused by Group A strep or rarely S. aureus), and Anthrax (also caused by S. aureus rarely).
- Erysipeloid is a superficial soft skin infection associated with animal products, hides, and meat caused by Erysipelothrix rhusiopathiae.
- Cellulitis is a diffuse deep epidermis and subcutaneous tissue infection.
- Folliculitis is an infected hair follicle, sometimes caused by P. aeruginosa (contaminated hot tubs).
- Furuncles (boils) are deep hair follicle infections.
- Carbuncles involve multiple hair follicles.
- Abscesses are collections of pus in skin and subcutaneous tissues.
- Soft tissue (wound) infections involve injured tissue (surgery, burns, bites) caused by many organisms including S. aureus, streptococci, and anaerobes.
- Burn wounds are often caused by S. aureus and P. aeruginosa.
- Animal bites can cause infection with Pasteurella multocida, Capnocytophaga canimorsus, S. aureus, or anaerobes. Human bites can cause infection from S. aureus or alpha-haemolytic streptococci.
- Myonecrosis is a severe muscle infection caused by Clostridium perfringens.
- Necrotizing fasciitis is a severe fascia infection caused by Group A strep and S. aureus.
- Decubitus ulcers (bed sores) are caused by bacteria near the rectum (Enterobacteriaceae, Pseudomonas, and Enterococci).
- Diabetic foot ulcers have slower-healing injuries, caused by S. aureus, streptococci, enterococci, Enterobacteriaceae, Pseudomonas aeruginosa, and anaerobes.
- Nodular lymphangitis is caused by Sporothrix schenckii, Nocardia spp., Actinomyces spp., and Mycobacteria.
- Systemic infections can cause dermatological manifestations, such as rashes from Borrelia burgdorferi (erythema migrans), T. pallidum, Rickettsiae, Leptospira, and Mycobacterium leprae.
- Viral infections, such as measles, chickenpox/shingles (Varicella-Zoster Virus), Herpes Simplex Virus, and warts (HPV), can also manifest in the skin.
- Toxin-mediated skin diseases include staphylococcal scalded-skin syndrome and toxic shock syndrome, both caused by S. aureus and S. pyogenes. Scarlett fever is caused by S. pyogenes.
- Specimen collection and transport should avoid surface contamination, and skin or mucous membranes should be decontaminated. Tissue and pus aspirates are preferred specimens, and tissue should be kept moist.
- Swabs are the least desirable specimens. When swabs are needed, they should be placed in transport media.
- Anaerobic infection analysis uses anaerobic transport media.
- Microscopic examination for infections uses gram staining, KOH, calcofluor white, or acid-fast staining to determine specimen quality and evaluate the presence of clinically relevant organisms.
Other Topics
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Cultures - Routine media (BAP, CHOC, MAC, PEA) vary based on setting, site, and suspected organisms. - Grow in 35°C in CO2. - Anaerobic cultures are necessary for closed wounds and abscesses. - Other cultures (Lowenstein-Jensen, Middlebrook, viral culture, Sabouraud's agar, eye, bone, BM, external ear) are used as well.
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Eye - Conjunctivitis: inflammation of the conjunctiva, potentially due to neisserial or chlamydial infections (prevented with eye drops in newborns) or haemophilus influenzae aegyptius or S. pneumoniae. - Keratitis: inflammation of the cornea, often due to trauma. - Endophthalmitis (rare): inflammation of the eyeball's interior. - Specimens: conjunctiva (swab), cornea (scraping), eye chamber fluid. - Processing: gram stain and cultures (BAP, CHOC, enriched broth, MAC, anaBAP).
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Osteomyelitis: infection of bone or bone marrow (most commonly caused by S. aureus) - Specimen collection: placed in enriched broth and pieces inoculated onto agar media (CHOC) - Bone marrow cultures are utilized only when Brucella or Mycobacteria are suspected, media choice depends on suspected organism.
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External Ear - Otitis externa (swimmer's ear): ear canal infection due to moisture. - Malignant otitis externa: severe invasive infection, sometimes linked to diabetes, and often caused by P. aeruginosa. - Specimens: debris from ear canal, collected with swab, gram stain cultures on BAP, CHOC, MAC
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Bioterrorism - The unlawful use (or the threat) of microorganisms or toxins from living organisms to cause death or disease in humans, animals, or plants. Intended to intimidate and instill fear. - Types include overt (immediate impact, early recognition) and covert (delayed response, recognized clinically). - History includes rye ergot (600 BC), WWI pathogens, Oregon salmonella, 2001 anthrax in the US. - Characteristics include low costliness, spread to large areas, and difficulty detecting. Common delivery methods include food/water, aircraft sprayers, vehicle sprayers, hand sprayers, and mail. - CDC developed the LRN (Laboratory Response Network) system in 1999 with sentinel labs (recognize, rule out, refer), reference labs (typing, confirmatory testing), and national labs (definitive characterization). - Categorization of potential bioterror threats (Category A, B, and C) depends on dissemination ease and impact (panic and social disruption).
- Anthrax (Bacillus anthracis) - Gram-positive, spore-forming bacillus. - Three forms of anthrax in humans: cutaneous, gastrointestinal, inhalation. - Cutaneous anthrax is most common, characterized by a skin lesion evolving to an eschar. - Gastrointestinal anthrax causes nausea, vomiting, bloody diarrhea, and significant mortality. - Inhalation anthrax begins with flu-like symptoms, leading to respiratory failure and sometimes meningitis. - Specimens: sputum, blood, stool, eschars, environmental samples. - Lab identification: gram stain (GPR spores), aerobic growth, nonhemolytic colonies, medusa-head colonies, catalase-positive, nonmotile.
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Plague (Yersinia pestis) - Distribution: highest in western states. Animal reservoir: prairie dog, deer mice, ground squirrels. - Transmission: inhalation, direct contact, fleas. - Clinical presentations include: bubonic (infected lymph nodes), septicemic (bloodborne organisms), necrotic changes, and pneumonic (aerosol, deadliest). - Specimens: bubo, lymph node aspirate, blood, sputum, bronchial washings, environmental, fleas, powder. - Lab identification: gram-negative bacilli, sometimes safety-pin appearance, slow growth (approx 2 days), nonhemolytic, fried egg colonies. nonmotile, Oxidase, urea and indole negative.
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Tularemia (Francisella tularensis) - Zoonotic infection spread through animals, including ticks and deer flies. - No person-to-person transmission. - Low to moderate mortality. - Clinical presentations include: glandular (adenopathy w/or w/out lesion), ulceroglandular (ulcer with adenopathy), oculoglandular (purulent conjunctivitis), typhoidal (sometimes presenting with flu-like features), and septicemia. - Specimens for lab: blood, tissue, lesion aspirate/swab, sputum, serum, environmental samples. - Lab ID: pleomorphic, small gram-negative rod, slow growth, grows on SBA, CHOC, and MTM buffered charcoal yeast-extract, nonmotile, catalase, oxidase, urea negative, BSL-2/3.
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Brucellosis (Brucella species) - Transmission is mainly through unpasteurized dairy products, direct skin contact with animals or contaminated aerosols. - Clinical symptoms include fever, profuse sweating, malaise, and muscle/back pain. - Low mortality rate (<5%). - Specimens: blood/bone marrow, serum, tissue, spleen, liver, abscesses, environmental/evidentiary samples. - Lab ID: slow growth, aerobic growth on BAP and CHOC, some strains grow on MAC, nonmotile, catalase, and oxidase, urea, positive.
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Burkholderia species (B. mallei/B. pseudomallei) - Transmission: direct contact with animals/occupational hazard. - Incubation period: 1 day - 2 weeks. - Clinical presentation: cutaneous, systemic, pneumonia. - Specimens: blood, bone marrow, sputum, bronchial alveolar lavage, abscess material, urine, serum. - Lab ID: growth after ~ 48 hours in CO2, larger nonpigmented colonies, becoming wrinkled.
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Q Fever (Coxiella burnetii) - Acquired through inhalation or contact with infected animals. - Characteristic spore-like bodies are found. - Clinical presentation: flu-like symptoms with pneumonia, hepatitis. - Mortality: around 2%. - Specimens for laboratory testing: blood, serum, body fluids, visceral tissue, biopsies, autopsies. Store at 4°C and use isolation and direct detection at reference labs.
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Botulism (Clostridium botulinum) - Neuroparalytic illness caused by a potent toxin. Seven types of botulinum toxin exist. - Types A, B, E, and F primarily affect humans, C and D birds and mammals, and Type G is undetermined. - Clinical symptoms can vary depending on source but include rapid progressive paralysis, double vision, and in severe cases, respiratory failure. - Infection can originate from food, wounds, or intentional release (bioterrorism). - Specimens for lab identification include serum, gastric contents, stool, food samples, autopsy specimens.
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Ricin
- Derived from castor bean waste.
- Various forms (powder, mist, pellet).
- Delivery methods primarily via inhalation.
- Highly stable substance.
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Description
Test your knowledge on infectious diseases, particularly those associated with animal exposure and skin infections. This quiz covers various pathogens, types of infections, and their characteristics. Evaluate your understanding of bacterial causes, inflammation, and specimen collection techniques related to dermatologic and systemic infections.
