Infectious Diseases Quiz

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Questions and Answers

What common presentation is associated with tularemia?

Neurological symptoms

Hemorrhagic fever

Bone marrow suppression

Glandular adenopathy without lesion (correct)

What is the primary reservoir for Francisella tularensis?

Rabbits (correct)

Dogs

Birds

Bats

Which of the following symptoms is NOT associated with brucellosis?

Profuse sweating

Muscle and back pain

High fever

Respiratory distress (correct)

What kind of disease does tularemia cause in rodents?

Plague-like disease Signup and view all the answers

Which method is used for lab identification of Francisella tularensis?

Culture on blood agar Signup and view all the answers

What is the incubation period for tularemia?

1 - 21 days Signup and view all the answers

What is the mortality rate for untreated tularemia?

30% Signup and view all the answers

Which of the following is a characteristic feature of the organism causing brucellosis?

Nonhemolytic in culture Signup and view all the answers

Which bacteria is commonly associated with decubitus ulcers?

Staphylococcus aureus Signup and view all the answers

What is a major pathogen in diabetic foot ulcers?

Pseudomonas aeruginosa Signup and view all the answers

Which organism is specifically associated with nodular lymphangitis?

Sporothrix schenckii Signup and view all the answers

Which organism causes erythema migrans?

Borrelia burgdorferi Signup and view all the answers

What type of stain can determine the quality of a specimen?

Gram stain Signup and view all the answers

Which medium is recommended for culturing anaerobic infections?

Anaerobic transport media Signup and view all the answers

Which type of swab is identified as least desirable for specimen collection?

Swabs in transport medium Signup and view all the answers

What is the primary method for culturing mycobacteria?

Middlebrook agar Signup and view all the answers

What is the primary function of the epidermis?

Act as a barrier to the environment Signup and view all the answers

Which organism is commonly associated with causing erysipelas?

Group A streptococci Signup and view all the answers

Which of the following is NOT considered a part of normal skin flora?

Bacillus anthracis Signup and view all the answers

Which type of infection is characterized by the presence of pus in the skin and subcutaneous tissue?

Abscess Signup and view all the answers

What type of organism is most associated with animal bites leading to skin infections?

Pasteurella multocida Signup and view all the answers

Which of the following infections is characterized by severe muscle infection known as gas gangrene?

Myonecrosis Signup and view all the answers

What is the primary causative agent in cellulitis?

Group A streptococci Signup and view all the answers

What type of infection involves multiple hair follicles?

Carbuncles Signup and view all the answers

What is the most common organism associated with osteomyelitis?

S. aureus Signup and view all the answers

Which organism is commonly responsible for malignant otitis externa?

Pseudomonas aeruginosa Signup and view all the answers

What type of specimen is collected for endophthalmitis diagnosis?

Eye chamber fluid Signup and view all the answers

What culture medium is used for culturing bone specimens?

CHOC Signup and view all the answers

Which type of bioterrorism event is characterized by immediate impact?

Overt Signup and view all the answers

What is the main method for diagnosing otitis externa?

Clinical diagnosis Signup and view all the answers

Which organism is associated with keratitis?

Variety of organisms, often due to trauma Signup and view all the answers

Which type of culture is commonly used for conjunctival specimens?

CHOC Signup and view all the answers

What is one of the primary characteristics of anthrax as a bioterror agent?

Cost-effective at $1 per attack Signup and view all the answers

What is the first sign of an anthrax attack?

Human illness Signup and view all the answers

In what particle size range is anthrax most effectively aerosolized?

1 to 5 microns Signup and view all the answers

Which delivery method is not commonly associated with bioterrorism strategies?

Social media campaigns Signup and view all the answers

What role does the Laboratory Response Network (LRN) play in public health?

Facilitates testing for biological threats Signup and view all the answers

Which of these is categorized as a Category A biological agent?

Yersinia pestis Signup and view all the answers

What factor may complicate the detection of a bioterror attack?

Agents being odorless and tasteless Signup and view all the answers

What is a main characteristic of Category B biological agents?

Spread through vectors Signup and view all the answers

Which delivery method involves using sprayers in a vehicle?

Vehicle sprayers Signup and view all the answers

What is a common effect of bioterrorism intended to be achieved by its perpetrators?

Creation of widespread panic Signup and view all the answers

What is the most common form of anthrax exposure?

Cutaneous Signup and view all the answers

What are the symptoms of inhalation anthrax?

Flu-like symptoms and respiratory failure Signup and view all the answers

Which of the following is NOT a form of human anthrax?

Septicemic Signup and view all the answers

What is the mortality rate of gastrointestinal anthrax?

50% Signup and view all the answers

What type of specimen is collected for inhalation anthrax identification?

Sputum Signup and view all the answers

Which strain of bacteria causes anthrax?

Bacillus anthracis Signup and view all the answers

What is the lethal dose of spores for inhalation anthrax infection?

5,000 – 8,000 spores Signup and view all the answers

Which form of plague is known to have the highest mortality rate?

Pneumonic Signup and view all the answers

What is a common symptom of bubonic plague?

Painful swollen lymph nodes Signup and view all the answers

How is Yersinia pestis primarily transmitted?

Inhalation and flea bites Signup and view all the answers

Study Notes

Skin and Soft Tissue

Skin consists of epidermis (outermost layer), dermis (hair follicles, sebaceous glands, sweat glands), subcutaneous layer (fat), fascia (fibrous tissue), and muscles.
Wound infections can result from trauma, gland obstruction, or follicle inflammation.
Infecting organisms can be endogenous (normal flora) or exogenous (outside the body).
Infections can be single or polymicrobial.
Skill is needed for recognizing and separating colony types in mixed infections.
Examples of normal skin flora include staphylococci (S. epidermidis & S. aureus), diphtheroids (Corynebacterium), micrococci, streptococci (non-hemolytic), Propionibacterium acnes, anaerobes, and yeast.

Dermatitis

Dermatitis represents skin inflammation.
Examples of agents causing dermatitis include Candida spp., S. aureus, coliforms, Corynebacterium spp., and molds (dermatophytes).

Pyoderma

Pyoderma is inflammation associated with pus.
Examples include Impetigo (blister-like skin infection, Group A streptococci and S. aureus), Erysipelas (superficial, painful infection with Group A streptococci and S. aureus; rarely, anthrax), and Erysipeloid (superficial skin infection of animal/ meat origin, with Erysipelothrix rhusiopathiae).

S. aureus and MRSA

Folliculitis involves infected hair follicles (sometimes due to P. aeruginosa contamination).
Furuncles (boils) are located deep in hair follicles.
Carbuncles involve multiple hair follicles.
Abscesses are pus collections in skin and subcutaneous tissue.

Soft Tissue (Wound) Infections

Soft tissue infections are caused by many organisms, such as S. aureus, Streptococci, and anaerobes, following injury, surgery, burns, or bites.
Burn wounds can be infected by S. aureus and Pseudomonas aeruginosa.
Animal bites can involve Pasteurella multocida, Capnocytophaga canimorsus, S. aureus, anaerobes, and rabies.
Human bites may result in S. aureus infection.

Myonecrosis

Gas gangrene, a severe muscle infection, is caused by C. perfringens.

Necrotizing Fasciitis

Necrotizing fasciitis is a very severe infection of the fascia, caused by Group A strep and S. aureus.

Decubitus Ulcers

Decubitus ulcers (bed sores or pressure sores) are caused by bacteria near the rectum (such as Enterobacteriaceae, Pseudomonas, and Enterococci).

Diabetic Foot Ulcers

Diabetic foot ulcers heal slowly, are prone to infections with S. aureus, streptococci, enterococci, Enterobacteriaceae, Pseudomonas aeruginosa, and anaerobes.

Nodular Lymphangitis

Nodular lymphangitis is caused by Sporothrix schenckii, Nocardia spp., Actinomyces spp., and mycobacteria.

Dermatologic Manifestations of Systemic Infections

Systemic infection dermatologic manifestations include rashes associated with Borrelia burgdorferi (erythema migrans), T. pallidum, Rickettsiae, Leptospira, and Mycobacterium leprae.
Viral infections can cause rashes with Measles (Rubeola and Rubella), Varicella-Zoster Virus (chicken pox/shingles), Herpes Simplex Virus, and Warts (HPV).
Parasites can also cause rashes that are discussed later, if needed.

Toxin-Mediated Skin Diseases

Staphylococcal scalded-skin syndrome and toxin shock syndrome result from toxins.
Scarlet fever is due to S. pyogenes toxins.

Specimen Collection and Transport

Avoid surface contamination of skin or mucus membranes before specimen collection.
Tissue and pus aspirates are preferred .
Specimens should remain moist.
Swabs are undesirable. Swabs, if used, should be placed in transport medium. Proper media is important for anaerobic infections.

Microscopic Examination

Gram staining detects many clinically significant organisms and determines specimen quality (reject if many epithelial cells are present—similar to sputum analysis).
Wet mount with KOH and calcofluor white and acid-fast stains are also used.

Culture

Bacterial isolates are common for skin infections (BAP, CHOC, MAC, PEA).
Growth media may vary based on site and presumed microbe.
CO2 may be required for growth.
Anaerobic cultures are necessary for closed wounds and abscesses.
Additional cultures (Lowenstein-Jensen, Middlebrook, for mycobacteria, viral culture in shell vials, and Sabouraud's agar) are available for diverse organisms.
Bone, BM, external ear, and eye cultures use appropriate samples and methods to detect organisms.

Eye

Eye cultures look for normal flora (C. Corynebacterium, viridans strep, Moraxella catarrhalis, staphylococci [S. aureus and CONS], Haemophilus influenzae, anaerobes, GNR).
Eye infections may be caused by H. influenzae aegyptius or S. pneumoniae.
Keratitis is cornea inflammation. Endophthalmitis is rare eyeball interior inflammation.
Specimen include conjunctival swab, corneal scraping, and eye chamber fluid.

Osteomyelitis

Osteomyelitis is a bone infection, most commonly caused by S. aureus.
Bone cultures are in enriched broth and inoculated onto agar media (CHOC) media.
Bone marrow cultures are only necessary in specific situations, for detecting Brucella or Mycobacteria. Media depends on organism.

External Ear

Otitis externa often results from moisture in the ear canal.
Malignant otitis externa is a severe infection, often with underlying conditions (diabetes). P. aeruginosa is usually the cause.
Specimens (debris) are removed with a swab for gram stain and cultures (BAP, CHOC, MAC).

Bioterrorism

Bioterrorism involves the unlawful use (or threat of use) of microorganisms or toxins from living organisms to cause death or disease in humans, animals, or plants for political or ideological reasons.
Biological agents can be overt (immediate impact, early event recognition) or covert (delayed response, clinically recognized).
Examples of historically used agents: 600 BC rye ergot (hallucinogen similar to LSD), WWI (anthrax, livestock disease), 1984 salmonella (restaurant outbreak), 2001 anthrax (NY & FL).
Cost-effectiveness is a key characteristic (e.g. anthrax, compared to nuclear weapons)
Threats can invoke panic, large areas are susceptible, & detection may be hard (agents are odorless, colorless, and tasteless).
Methods of delivery include liquid or powder aerosols, particulate (1–5 micron size) dispersed by weather patterns, and contamination of food or water.
Examples of delivery methods: food/water, aircraft sprayers, vehicle sprayers, hand sprayers, and mail.
The CDC’s Laboratory Response Network (LRN) responds to bioterrorism and chemical public health threats. LRN Labs: sentinel (clinical, recognize & refer), reference (confirm), national (CDC, military, definitive characterization).
Examples of agents for category A: Yersinia pestis (bubonic plague), Variola major (smallpox), Bacillus anthracis (anthrax), Clostridium botulinum.
Category B: E. coli O157:H7 (foodborne illness), other toxins, psittaci (parrot fever).
Category C agents include; emerging threats and are not yet prominent.

Anthrax

Anthrax is caused by Bacillus anthracis, a gram-positive, spore-forming bacterium.
Anthrax causes cutaneous, gastrointestinal, and inhalational forms of illness.
Cutaneous anthrax is characterized by a skin lesion that evolves from a papule through a vesicular stage to a depressed black eschar (scar).
Gastrointestinal anthrax is caused by spore ingestion and presents with nausea, vomiting, bloody diarrhea, and potentially fatal sepsis.
Inhalation anthrax begins with flu-like symptoms, leading to respiratory failure, and high mortality. Samples for each subtype are distinctly different. Lab tests are available for identification, but each requires varied and specific tools and techniques.

Plague

Plague is caused by Yersinia pestis.
Transmission methods are via inhalation, direct contact, and fleas.
The illness can be in bubonic, septicemic, or pneumonic forms.
Bubonic occurs via infected lymph nodes, septicemic via the bloodstream, and pneumonic via aerosol transmission.

Tularemia

Tularemia is caused by Francisella tularensis.
Transmission methods include contact with infected animals or their vectors.
Transmission is not person-to-person and has a low mortality rate (depending on type and treatment).
Subtypes of tularemia include; pneumonic, glanular, ulceroglandular, oculoglandular, and septicemic.
A variety of samples may be taken, including; blood, tissue, lesion aspirate, sputum, and serum.
Identification is by slow growth, typically pleomorphic small gram-negative rods, characteristic growth on certain media (SBA, CHOC, MTM & buffered charcoal yeast-extract), nonmotility, and negative catalase, oxidase, or urea tests.

Brucellosis

Brucellosis is an illness caused by Brucella species.
The most common transmission methods are unpasteurized dairy products and direct contact with infected animals. Other transmission methods include aerosols.
The symptoms include fever, profuse sweating, malaise, headache, and muscle/back pain.
The disease has a very stable organism persistence, and low mortality rate (less than 5%).
Specimens may include blood, bone marrow, serum, tissue, spleen, liver, and abscesses.

Burkholderia Species

Burkholderia species include B. mallei (glanders), and B. pseudomallei (meliodosis).
Transmission involves direct animal contact.
Incubation time is typically 1-2 weeks and illness presentations include cutaneous, systemic and pneumonia infections.
Specific specimens needed may include blood, bone marrow, sputum, and bronchial alveolar lavage, abscess material, urine, and serum.

Q Fever

Q Fever is caused by Coxiella burnetii.
Transmission occurs through inhalation of infected animals.
Spore-like bodies are present and symptoms typically include flu-like symptoms, pneumonia, or hepatitis.
Mortality is low (2%).

Smallpox

Smallpox is caused by the orthopox virus Variola major.
Symptoms include an initial incubation period (8–16 days), followed by initial symptoms (prodrome), and rash development and spread over 7 days.
The rash progresses through macules, vesicles, and pustules before finally forming scabs.
Smallpox was eradicated from most of the world by 1977, but it remains a potential bioweapon threat.
Specimens for diagnostics will vary based on the stage of the disease, but care for smallpox should be carried out with a high degree of safety.

Viral Hemorrhagic Fever

Viral hemorrhagic fevers are caused by various viruses (e.g., Ebola, Marburg, Lassa, Hantavirus, Flaviviruses [Tick-borne Encephalitis, dengue, Yellow Fever]).
The symptoms vary depending on the specific virus, but some common symptoms include fever, general weakness, muscle pains, and bleeding problems.
Specimens may include; blood, serum, body fluids, visceral tissues, biopsies, and autopsies.

Botulism

Botulism is caused by Clostridium botulinum.
There are seven types of botulinum toxins; A, B, C, D, E, F and G.
The resulting illness is a neuroparalytic one, likely due to toxin action.
4 main types are associated with human illness.
Foodborne botulism symptoms are rapid progression of diplopia (double vision), blurred vision, flaccid, symmetric paralysis.
Infant botulism is often associated with constipation, poor feeding, and respiratory failure.
Wound botulism symptoms are similar to those of foodborne botulism, only that infections are through wounds.
Other botulism presentations are in non-infant cases with no suspected food or wound origin.
Specimen selection depends on suspicion (food, wound, or possible terroristic action), but includes blood serum, gastric contents or vomit, stool, food, and autopsy samples (tissue from GI tract) .

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Description

Test your knowledge on infectious diseases, focusing on tularemia, brucellosis, and related pathogens. This quiz covers various aspects including reservoirs, symptoms, laboratory identification methods, and culturing techniques. Sharpen your understanding of these critical health topics.