Microbiology for the Healthcare Professional Test Answers – Flashcards

The genus Streptococcus is composed of spherical gram-positive bacteria well known for being responsible for "strep throat," but also capable of causing meningitis, pneumonia,  endocarditis, erysipelas, necrotizing fascilitis, and toxic shock syndrome.

The virulence of group A Streptococcus seems to be increasing worldwide.

• ORGANISM: Group A Streptococcus
• TARGET OF INFECTION: Pharynx
• TRANSMISSION: Nasal or salivary secretions; person-to-person contact
• This is the most common bacterial infection of the throat. It occurs mostly in children 5-15 years of age and is seen mainly during late fall, winter, and early spring
• Although most pharyngitis is viral, a throat culture should be obtained being that Group-A Strep in some forms can lead to rheumatic fever

• ORGANISM: Streptococcus pyogenes
• TARGET OF INFECTION: Pharynx, tongue
• TRANSMISSION: Direct contact with infected person; nasal droplets; fomites such as shared drinking glasses
• Is an upper respiratory disease also caused by an infection with a group A B-hemolytic streptococcus (Streptococcus pyogenes)
• Begins with fever and sore throat, might exhibit chills, vomiting, abdominal pain, and malaise
• The exotoxins produced by the bacterial is responsible for the "strawberry" tongue along with a fine rash on the chest, neck, groin, and thighs

• ORGANISM: Streptococcus pneumoniae
• TARGET OF INFECTION: Pharynx, lungs, alveoli
• TRANSMISSION: Person-to-person contact
• Is a gram-positive, encapsulated a-hemolytic diplococcus
• Also known as pneumococcus, common cause of mild respiratory illness, but also a major source of pneumonia
• Capable of causing: pharyngitis, sinusitis, otitis media, meningitis, osteomyelitis, septic arthritis, endocarditis, peritonitis, pericarditis, cellulitis, and brain abscess
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• ORGANISM: Mycoplasma pneumoniae
• TARGE OF INFECTION: Lungs; mucous membranes
• TRANSMISSION: Nasal secretions among people in croweded environments
• Causes a typical pneumonia
• A mild form of pneumonia that occurs in people less than 40
• Spreds via person-to-person by droplet contact
• Epidemics are seen in crowded places like schools, military, homeless shelters and among families
• Small baacterium that lacks a cell wall
• DO NOT treat with penicillin because of the lack of a cell wall

• ORGANISM:  Clamydia pneumoniae
• TARGET OF INFECTION: Lungs
•  TRANSMISSION: Inhalation of respiratory droplets
• NOW CALLED CHLAMYDOPHILA PNEUMONIAE
• A major cause of bronchitis and pneumonia
• Begins with a cough and progresses into pneumonia with little or no fever
• Pretty common with all age groups but seen mostly in school children
• Treated with the antibiotic  erythromycin

• ORGANISM: Bordetella pertussis
• TARGET OF INFECTION:  Trachea-ciliated epithelial cells
• TRANSMISSION: Inhalation of respiratory droplets
• Gram-negative
• An extremely small, aerobic coccobacillus
• Highly contagious disease
• A very serious disease that can cause permanent disability or even death
• Vaccine is available
• Treatment with antibiotics to shorten the infectious period

• ORGANISM:  Mycobacterium tuberculosis
• TARGET OF INFECTION: Lungs
• TRANSMISSION: Inhalation of respiratory droplets
• A deadly disease
• It can infect other parts of the body as well as the lungs
• Most people infected with the organism DO NOT show symptoms
• The elderly, immigrants entering the United States, failure to complete antibiotic regimes and HIV/AIDS patients are at high risk
• Antibiotic treatment is available 

• ORGANISM: Staphylococcus aureus; S. pneumoniae
• TARGET OF INFECTION:  Lungs
• TRANSMISSION: Nosocomial; complication after influenza
• Gram-positive coccus
• Causes only 2% of community-acquired pneumonias; 10% to 15% of hospital-aacquired pneumonias
• Occurs in people who are hopitalized with another disease often very young, the old and dibilitating illness
• 15%-40% leading to death
• Treatment is usually a type of penicillin

• ORGANISM: Haemophilus influenzae
• TARGER OF INFECTION: Pharynx, bronchi, lungs
• TRANSMISSION: Inhalation of respiratory droplet
• Gram-negative coccobacillus
• Part of the normal flora in the upper airways of children and adults rarely cause disease
• Common infection in children is bronchitis and in adults chronic bronchitis; occasionally meningitis
• H. influenzae and S. pneumoniae are sometimes isolated from the same individual
• Children are vaccinated against Haemophilus influenzae type b especially meningitiss

• ORGANISM: Klebsiella pneumoniae
• TARGET OF INFECTION: Lungs
• TRANSMISSION: Nosocomial
• Gram-negative, encapsulated bacillus 
• Found in normal flora of the mouth, skin, and intestines
• Mainly effects patients in hospitals and nursing homes
• Infection is serious and persons are treated with antibiotics, supplemental oxygen, and intravenous fluids
• Despite treatment the death toll ranges from 25% to 50% of infected patients

• ORGANISM: Corynebacterium diptheriae
• TARGET OF INFECTION: Respiratory membranes
• TRANSMISSION: Inhalation of respiratory droplet
• Gram-positive, facultative anaerobic
• Characterized by: sore throat, low-grade fever, and the formation of pseudomembrane on the tonsils and pharynx which can lead to life threatening obstruction of airways
• Highly contagious
• Bacterium produces exotoxins that can spread through the bloodstream to other organs and cause significant damage
• Vaccine  is available; treatment includes antitoxins to eliminate the toxin and antibiotice to eliminate the toxin-producing bacteria

 Viral Infection 

Although many bacteria are part of the resident normal flora of the upper respiratory system, a large number of viruses are probably part of the transient flora of he nasopharyngeal cells.

Most virions that are able to reach the lungs are destroyed by alveolar macrophages.

An estimated 90% of acute upper respiratory and approximately 50% of lower respiratory infections are caused by viruses.

Fungal Infection

Fungi can cause infections of the skin, hair, nails, and also of the respiratory system.

Respiratory diseases caused by fungi most commonly involve the lungs and are referred to as deep mycoses.

Dimorphism in some fungi can aid in infection as the single-celled yeast can more easily spread throughout the body via the bloodstream.

• ORGANISM: Influenza virus
• TARGET OF INFECTION: Lungs; respiratory tract
• TRANSMISSION: Inhalation of airborne viruses; via fomites
• RNA viruses designated as types A, B, and C
• Caused by orthomyxoviruses
• Flu viruses are the primary causes of epidemics and endemics of the respiratory system
• Because influenza kills epithelial cells, it leaves the host susceptible for secondary bacterial infections especially in the lungs

• ORGANISM: can be caused by serveral viruses including: influenza viruses, parainfluenza, adenovirus, rhinovirus, herpes simplex virus, respiratory syncytial virus, hantavirus and cytomegalovirus
• TRANSMISSION: Person-to-person contact; respiratory droplets
• Just about half of all pneumonias are caused by viruses
• Generally these viruses are rather mild, except if the individual is immunosuppressed
• Antibiotics are ineffective against viruses

• ORGANISM: Hantaviruses
• Carried by rodents; CDC has placed emphasis on being able to control the rodent population
• Deadly disease
• Person-to-person contact is likely but HAS NOT been reported
• Primarily spread by urine and droppings by rodents
• Infection at first appears similar to a severe cold or influenza and is accompanied by fever and muscle achess
• Quickly progresses to severe respiratory difficulties and to acute respiratory distress syndrome (ARDS)

• The causative virus with SARS is the coronaviruse.
• SARS was thought to have originated out of mainland China  (Novemeber 2002); spread worldwide over several months
• SARS is spread by close person-to-person contact in which droplet formation is transferred to mucous membrane contact
• SARS can be life-threatening
• Symptoms: high fever, headache, body aches, dry cough, followed by pneumonia

• Histoplasma capsulatum infections are generally acute respiratory infections that occur in all age groups and in both sexes
• Disease affects primarily the lungs and occasionally other organs
• Transmission occurs by inhalation of airborne conidia of the the fungus
• Reserviors of he organism can be found in soil around old chicken houses, starling bird roosts, and bat caves
• Spread primarily by bird dropping
• Acute infection shows symptoms that resemble those of tuberculosis; including fever, headache, and nonproductive cough

• Causative agent is Coccidioides immitis
• This fungus resides in the southwestern part of the United States mainly in desert regions
• Usually breathed in via dust, rodent borrows, and archeological sites
• Exposure often occurs after natural disasters such as dust storms and earthquakes
• Only 40% lead to symptoms ranging in degree from mild to severe
• Symptoms present as cough, chest pain, fever, chills, night sweats, headache, muscle stiffness, muscle aches, joint stiffness, neck and shoulder stiffness, rash, blood-tinged sputum, loss of appetite, weight loss, wheezing, excessive sweating, change in mental status, and sensitivity to light

• Caused by one or more species of Aspergillus, a mold commonly found in decaying plants, stored hay, compost piles, bird dropping, and any site where excess dust accumulates, also in hospital environment
• Areas like shower heads, and hospital water storage tanks are susceptible
• The elderly, immigrants entering the United States, patients who fail to finish antibiotic regimens, and HIV/AIDS
• At present time no person-to-person transmission evident