Microbiology in Clinical Medicine
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Questions and Answers

What type of ulcers are caused by S.aureus and other bacteria?

  • Dermatologic Manifestations
  • Nodular Lymphangitis
  • Decubitus Ulcers
  • Diabetic Foot Ulcers (correct)

Which organism is primarily associated with nodular lymphangitis?

  • Pseudomonas
  • Sporothrix schenckii (correct)
  • Enterobacteriaceae
  • Staphylococcus aureus

What is the least desirable specimen collection method?

  • Blood samples
  • Pus aspirates
  • Swabs (correct)
  • Tissue samples

Which stain is commonly used for microscopic examination to detect significant organisms?

<p>Gram stain (C)</p> Signup and view all the answers

What type of media is used for anaerobic culture?

<p>Anaerobic transport media (D)</p> Signup and view all the answers

Which organism is associated with scarlet fever?

<p>Streptococcus pyogenes (A)</p> Signup and view all the answers

What method should be used for specimen transportation to avoid contamination?

<p>Decontaminate skin or mucous membrane before collection (B)</p> Signup and view all the answers

Which bacterium is commonly found in eye infections?

<p>Corynebacterium (B)</p> Signup and view all the answers

Which organism is most commonly associated with osteomyelitis?

<p>Staphylococcus aureus (B)</p> Signup and view all the answers

What method is used to collect conjunctival specimens?

<p>Swab (C)</p> Signup and view all the answers

Which condition is associated with trauma to the cornea?

<p>Keratitis (B)</p> Signup and view all the answers

What is a common cause of malignant otitis externa?

<p>Pseudomonas aeruginosa (B)</p> Signup and view all the answers

What is the initial processing method for bone cultures?

<p>Inoculated onto enriched broth (A)</p> Signup and view all the answers

What type of bioterrorism involves immediate impact and early recognition of an event?

<p>Overt (D)</p> Signup and view all the answers

What media is most likely used for culturing endophthalmitis?

<p>anaBAP (A)</p> Signup and view all the answers

Which event involved an outbreak of Salmonella in a restaurant?

<p>1984 Oregon case (B)</p> Signup and view all the answers

What layer of the skin is the outermost layer?

<p>Epidermis (B)</p> Signup and view all the answers

Which of the following is considered an endogenous organism that can lead to wound infections?

<p>Staphylococcus aureus (C)</p> Signup and view all the answers

What type of infection is characterized by inflammation accompanied by pus?

<p>Impetigo (B)</p> Signup and view all the answers

Which organism is primarily associated with gas gangrene?

<p>C.perfringens (B)</p> Signup and view all the answers

Which type of infection involves dermal and subcutaneous diffuse infection?

<p>Cellulitis (A)</p> Signup and view all the answers

What is a common cause of folliculitis?

<p>S. epidermidis (B)</p> Signup and view all the answers

Which organism is known for causing serious infections from animal bites?

<p>Pasteurella multocida (D)</p> Signup and view all the answers

Which condition is characterized by inflammation of the fascia and is considered very severe?

<p>Necrotizing Fasciitis (B)</p> Signup and view all the answers

What is a significant characteristic of anthrax as a bioterror agent?

<p>It is tasteless and odorless. (C)</p> Signup and view all the answers

Which method is NOT commonly associated with biological delivery methods?

<p>Land mines (D)</p> Signup and view all the answers

Which factor is essential for the successful dispersal of aerosols of bioterror agents?

<p>Particle sizes of 1 to 5 microns (D)</p> Signup and view all the answers

What is the primary first sign of a bioterror attack involving biological agents?

<p>Human illness (D)</p> Signup and view all the answers

Which laboratory level is responsible for confirmatory testing of biological agents?

<p>Reference Labs (D)</p> Signup and view all the answers

What is one of the criteria for categorizing biological agents?

<p>Ease of dissemination (A)</p> Signup and view all the answers

Which of the following is an example of a Category A biological agent?

<p>Yersinia pestis (C)</p> Signup and view all the answers

What impact can the threat of a biological attack create?

<p>Panic among the population (A)</p> Signup and view all the answers

What delivery method involves the use of animals in the spread of biological agents?

<p>Animal Vector (A)</p> Signup and view all the answers

Which type of pathogen may be involved in bioterror attacks and can be contagious?

<p>Pathogenic bacteria (A)</p> Signup and view all the answers

What is the most common form of human anthrax?

<p>Cutaneous anthrax (D)</p> Signup and view all the answers

What is the mortality rate associated with gastrointestinal anthrax?

<p>50% (D)</p> Signup and view all the answers

Which anthrax form has the highest mortality rate?

<p>Inhalation anthrax (A)</p> Signup and view all the answers

Which of the following is NOT a symptom of inhalation anthrax?

<p>Nausea (D)</p> Signup and view all the answers

What is the characteristic appearance of colonies when identifying Bacillus anthracis in the lab?

<p>Medusa-head (C)</p> Signup and view all the answers

Which vector is primarily responsible for the transmission of Yersinia pestis?

<p>Fleas (D)</p> Signup and view all the answers

What is a distinguishing symptom of bubonic plague?

<p>Painful buboes (B)</p> Signup and view all the answers

Which clinical presentation of plague is transmissible by aerosol?

<p>Pneumonic plague (B)</p> Signup and view all the answers

What is the common incubation period for gastrointestinal anthrax after ingestion of spores?

<p>2-5 days (D)</p> Signup and view all the answers

Which spore count is associated with the onset of inhalation anthrax?

<p>5,000 – 8,000 spores (B)</p> Signup and view all the answers

What is the infective dose for Tularemia?

<p>10 - 50 organisms (A)</p> Signup and view all the answers

Which of the following is NOT a clinical presentation of Tularemia?

<p>Chronic fatigue syndrome (D)</p> Signup and view all the answers

Which diagnostic agar shows small non-lactose fermenting colonies for a specific organism?

<p>MAC (C)</p> Signup and view all the answers

What is the mortality rate of untreated Tularemia?

<p>30% (B)</p> Signup and view all the answers

Which of the following is a zoonotic infection associated with a rabbit?

<p>Tularemia (D)</p> Signup and view all the answers

What is the duration of illness typically seen in patients with Tularemia?

<p>2 weeks (D)</p> Signup and view all the answers

Which method is NOT typically associated with diagnosing Tularemia?

<p>Bone marrow biopsy (A)</p> Signup and view all the answers

What is the expected incubation period for Tularemia?

<p>1 - 21 days (D)</p> Signup and view all the answers

Flashcards

Dermatitis

Inflammation of the skin, often caused by various bacteria like Staphylococcus aureus, Candida spp., and Dermatophytes.

Folliculitis

An infected hair follicle, often caused by bacteria like Staphylococcus aureus and sometimes Pseudomonas aeruginosa.

Furuncle (boil)

A deeper infection than folliculitis, occurring within hair follicles, caused by Staphylococcus aureus.

Carbuncle

A severe infection involving multiple hair follicles, often caused by Staphylococcus aureus.

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Abscess

A localized collection of pus within the skin and subcutaneous tissue, often caused by various bacteria.

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Gas Gangrene

Severe infection of muscle tissue, commonly caused by Clostridium perfringens, leading to gas production.

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Necrotizing Fasciitis

A very severe infection affecting the fascia (connective tissue), often caused by Group A Streptococcus and Staphylococcus aureus.

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Endogenous Skin Infection

Infection of the skin caused by bacteria that normally inhabit the skin, such as Staphylococcus epidermidis and Staphylococcus aureus.

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Conjunctivitis

Inflammation of the conjunctiva, the clear membrane lining the inner surface of the eyelid and the white part of the eye.

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Osteomyelitis

Infection of the bone or bone marrow, often caused by Staphylococcus aureus.

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Bioterrorism

The unlawful use, or threatened use, of microorganisms or toxins to cause death or disease.

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Overt bioterrorism

Rapidly noticed and immediate impact.

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Covert bioterrorism

Delayed effects, usually recognized through clinical symptoms.

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Immediate impact

A type of bioterrorism where the immediate impact is clear and recognizable.

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Delayed response

A type of bioterrorism where the effects are delayed and often recognized through clinical symptoms.

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Decubitus Ulcers (Bed Sores/Pressure Sores)

A bacterial infection that causes bed sores or pressure sores, commonly found near the rectum. The bacteria involved include Enterobacteriaceae, Pseudomonas, and Enterococci.

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Diabetic Foot Ulcers

Ulcers on the feet of diabetic patients, which heal slowly due to impaired blood flow and nerve sensation.

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Dermatologic Manifestations of Systemic Infection

Skin eruptions or rashes caused by systemic infections, meaning the infection is affecting the whole body. Examples include Lyme disease (Borrelia burgdorferi) causing erythema migrans (bulls-eye rash), syphilis (T. pallidum) causing chancres, and leprosy (Mycobacterium leprae) causing skin lesions.

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Dermatologic Manifestations of Systemic Infection: Viral

Viral infections that can cause skin eruptions and rashes. Examples include Measles (Rubeola and Rubella), Chickenpox/Shingles (Varicella-Zoster Virus), Herpes Simplex Virus, and Warts (Human Papillomavirus).

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Toxin-Mediated Skin Diseases

Toxin-mediated skin diseases caused by bacterial toxins. Examples include Staphylococcal scalded-skin syndrome and Toxic Shock Syndrome (caused by S. aureus and S. pyogenes).

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Specimen Collection and Transport

The process of collecting and transporting specimens for microbiological analysis. Emphasizes avoiding contamination, using appropriate methods, and selecting appropriate media for culturing bacteria.

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Microscopic Examination

Microscopic examination using techniques like Gram staining to detect bacteria, KOH and calcofluor white staining to identify fungi, and acid-fast staining for Mycobacteria.

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Cultures (Bacterial)

Cultivating bacteria on different growth media to isolate and identify the specific organism causing the infection.

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Cutaneous Anthrax

A bacterial infection that causes a skin lesion, often starting as a small bump and eventually becoming a black, dead, flesh area.

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Gastrointestinal Anthrax

A bacterial infection that starts with the ingestion of spores. It can cause a wide range of symptoms, including nausea, vomiting, diarrhea, and bloody stools.

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Inhalation Anthrax

A potentially fatal bacterial infection that starts with inhaling spores. Symptoms start similar to the flu but worsen rapidly, leading to breathing difficulties and sometimes meningitis.

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Bacillus anthracis

A bacterium responsible for Anthrax infections. It is a gram-positive, spore-forming bacillus.

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Plague

A bacterial infection known as the Black Death, transmitted by fleas, direct contact with infected animals, or inhalation of infected droplets.

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Bubonic Plague

One of the 3 major types of plague. It is characterized by swollen, painful lymph nodes called 'buboes.'

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Septicemic Plague

A severe form of plague where the bacteria spread through the bloodstream. It can cause necrosis and skin damage.

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Pneumonic Plague

The most dangerous form of plague, spread through the air (aerosol). It can cause lung infection and is highly contagious.

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E. coli O157:H7

A specific type of E. coli bacteria that produces toxins causing severe diarrhea and other health problems.

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Category C Agents

A category of potential biological threats that require enhanced lab capacity and can cause moderate illness with a low but not insignificant mortality rate.

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Tularemia

A bacterial infection characterized by slow growth on culture media, often producing colonies with a "fried egg" appearance, known for its ability to survive in the environment for months.

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Francisella tularensis

The causative agent of tularemia, this bacterium is known for its ability to infect a wide range of hosts, including rabbits, ticks, and even water rats.

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Incubation period of Tularemia

The time it takes for symptoms to appear after exposure to F. tularensis, typically ranging from 1 to 21 days with an average of 3 to 5 days.

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Infective Dose of Tularemia

The number of F. tularensis organisms required to cause infection, usually a small amount, only 10-50 organisms.

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Glandular Tularemia

The most common form of tularemia, characterized by swollen lymph nodes (adenopathy) without an ulcer.

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Ulceroglandular Tularemia

A severe form of tularemia, characterized by an ulcer at the site of infection and swollen lymph nodes.

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Pneumonic Tularemia

A rare form of tularemia that affects the lungs, causing flu-like symptoms, and potentially fatal if untreated.

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Persistence of Francisella tularensis

The ability of F. tularensis to survive for months in moist soil, highlighting the potential for environmental transmission.

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Anthrax

A biological agent that can be easily produced and dispersed, causing widespread panic and potential for high casualties. Known for its relatively low cost compared to other weapons.

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Laboratory Response Network (LRN)

A network of laboratories established by the CDC to respond to biological and chemical public health threats. LRN labs provide timely and accurate testing and reporting to local, state, and federal agencies.

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Sentinel Lab

A type of LRN laboratory that provides initial testing and recognition of potential biothreats. They rule out common diseases and refer samples to specialized labs if necessary.

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Reference Lab

A type of LRN laboratory that focuses on confirming the presence of specific biothreat agents and performing detailed analysis. They provide definitive identification and characterization of threats.

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Contagious spread

The ability of a biological agent to spread from person to person, either through direct contact or through airborne droplets. This makes it difficult to contain and can cause widespread outbreaks.

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Aerosol delivery

The deliberate release of biological agents into the air, targeting a large population area. This is a common method in bioterrorism attacks, as it can affect many people quickly.

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Food or water contamination

The intentional contamination of food or water supplies with biological agents. This can cause large-scale illness and disruption, making it a very effective method of attack.

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Category A Bioterrorism Agents

Biological agents that pose the highest risk to public health due to their ease of dissemination, potential for high mortality, and potential for panic and social disruption.

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Category B Bioterrorism Agents

Biological agents that pose a less serious threat than Category A agents, but still have the potential for public health impact. They are easier to acquire and use, which makes them concerning threats.

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Study Notes

Skin and Soft Tissue

  • Skin is composed of the 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 (external).
  • Single or polymicrobial infections are possible, and skill is needed to differentiate colony types in mixed cultures.
  • Common normal skin flora includes staphylococci (S. epidermidis & S. aureus), diphtheroids (Corynebacterium), micrococci, streptococci (non-hemolytic), Propionibacterium acnes, anaerobes, and yeast.
  • Dermatitis is skin inflammation, and causes can include Candidia spp., S. aureus, coliforms, Corynebacterium spp., and moulds (dermatophytes).
  • Pyoderma is inflammation with pus. Examples include impetigo (blister-like superficial skin infection caused by Group A streptococci or S. aureus), erysipelas (superficial, painful infection caused by Group A streptococci or rarely S. aureus), erysipeloid (superficial soft skin infection associated with animal products and caused by Erysipelothrix rhusiopathiae), and cellulitis (deep infection of epidermis and subcutaneous tissues caused by Group A streptococci or S. aureus).
  • S. aureus and MRSA infections can cause folliculitis (infected hair follicle, sometimes due to P. aeruginosa), furuncles (boils, deep hair follicles), and carbuncles (multiple hair follicles).
  • Abscesses are collections of pus in skin and subcutaneous tissues.
  • Soft tissue (wound) infections are caused by many organisms, including S. aureus, streptococci, and anaerobes.
  • Burn wounds can result from S. aureus and P. aeruginosa infections.
  • Animal bites can cause infections from Pasteurella multocida, Capnocytophaga canimorsus, or S. aureus; also, rabies.
  • Myonecrosis (gas gangrene) is a severe muscle infection caused by C. perfringens.
  • Necrotizing fasciitis is a severe infection of fascia.
  • Decubitus ulcers (bed sores) are pressure sores caused by bacteria near the rectum (e.g., Enterobacteriaceae, Pseudomonas, Enterococci).
  • Diabetic foot ulcers are slow-healing injuries caused by S. aureus, streptococci, enterococci, Enterobacteriaceae, Pseudomonas aeruginosa, and anaerobes.
  • Nodular lymphangitis is caused by Sporothrix schenckii, Nocardia spp., Actinomyces spp., or Mycobacteria.
  • Dermatologic manifestations of systemic infections can include rashes from Borrelia burgdorferi (erythema migrans), T. pallidum, Rickettsiae, Leptospira, or Mycobacterium leprae.
  • Examples of viral infections that cause dermatologic manifestations include measles, chickenpox/shingles (varicella-zoster virus), herpes simplex virus, and warts (HPV).
  • Toxin-mediated skin diseases include staphylococcal scalded-skin syndrome, and toxin shock syndrome caused by S. aureus and S. pyogenes.
  • Scarlet fever is caused by S. pyogenes.
  • Skin specimen collection should avoid surface contamination, decontaminate skin/mucosa before collection, and preferably use tissue and pus samples. Swabs are least desirable, but if used, should be placed in transport medium. Anaerobic transport media are needed for anaerobic infections.
  • Gram stain is done for microscopic examination to detect clinically significant organisms. The quality of the specimen is assessed, rejecting those with many epithelial cells.
  • KOH and calcofluor white wet mounts, and acid-fast stains are also used in microscopic examination.
  • Culture processes may use BAP, CHOC, MAC, PEA, and media may vary based on setting, site, and organisms suspected.
  • Anaerobic cultures are recommended for closed wounds and abscesses.
  • Additional cultures may include Lowenstein-Jensen and Middlebrook media, viral cultures, shell vials, and Sabouraud's agar. cultures can be done for eye, bone, bone marrow, and external ear samples.
  • Conjunctivitis is an eye inflammation, and is often caused by Haemophilus influenzae aegyptius, S. pneumoniae in newborns. Keratitis of the cornea is often caused by trauma, and endophthalmitis is a rare infection of the eyeball's interior. Conjunctival specimens are collected with a swab, corneal scrapings use a platinum spatula, and specimens are inoculated at bedside.
  • Processing methods include microscopic examination of gram-stained cultures, BAP, CHOC, enriched broth (with anaBAP for some situations like endophthalmitis), and CHOC media.
  • Osteomyelitis is a bone or bone marrow infection; S. aureus is the most common cause. Bone cultures use enriched broth and agar media. Bone marrow cultures are done, if necessary, for detecting Brucella or Mycobacteria, depending on the organism sought.
  • Otitis externa, swimmer's ear, is due to moisture in the ear canal. Malignant otitis externa is a severe, invasive infection, often seen with underlying conditions like diabetes, and P. aeruginosa is the most common cause.
  • Diagnosed cases are assessed clinically, and malignant or recurrent cases require culturing of debris removed from the ear canal. Gram stains are taken, and cultures are performed using BAP, CHOC, and MAC media.
  • Bioterrorism involves the unlawful use of microorganisms or toxins derived from living organisms to incite fear and intimidate. These agents of bioterriorism may be covert and overt, and their delivery methods include aerosolization, food/water contamination, and vectors. Common characteristics of bioterror agents include inexpensive production, large attack area capability, difficult detection, and quick onset. These agents can be delivered through food or water contamination, aircraft sprayers, vehicle sprayers, hand sprayers, or mail systems. The Laboratory Response Network (LRN) was established for responding to biological and chemical public health threats.

Other Topics (refer to specific sections for details)

  • Category A, B, C bio-defense agents
  • Anthrax
  • Plague
  • Tularemia
  • Botulism
  • Q fever
  • Smallpox
  • Viral hemorrhagic fevers

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Test your knowledge on the various microorganisms associated with different medical conditions. This quiz covers topics related to bacterial infections, specimen collection methods, and culture media, specifically in a clinical context. Ideal for students and professionals in microbiology or healthcare.

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