3 Normal Bacterial Flora (11) Flashcards
The term carrier implies that:
1 An individual is suffering from a disease
2 An individual harbors a potential pathogen and therefore can be a source of infection to others
3 An individual is recovering from a disease
4 An individual has an abnormal flora composition
An individual harbors a potential pathogen and therefore can be a source of infection to others
The term carrier is most frequently used in reference to asymptomatic infection or to a patient who has recovered from a disease but continues to carry the organism and may shed it for a long time.
The normal flora of the urogenital tract includes which of the following?
1 Pseudomonas aeruginosa
2 Proteus spp
3 Klebsiella spp
4 Corynebacterium spp
5 Enterococcus spp
Corynebacterium spp
Microorganisms usually found in the urogenital tract are Bacteroides, Borrelia spp., Corynebacterium spp., Clostridium spp., Lactobacillus spp. and Leptotrichia.
Pseudomonas aeruginosa, Proteus spp., Enterococcus spp., and Klebsiella spp are common pathogens that cause urinary tract infections.
Fusobacterium is a normal inhabitant of
1 Skin
2 Mouth
3 Eye
4 Ear
5 Nose
Mouth
Fusobacterium is anaerobic and can be found in mouth and intestine. Other anaerobes colonizing mouth includes Peptostreptococcus, Prophyromonas, Bacteroides, and Actinomyces.
At the time of birth, newborn girls’ vaginas are colonized with
1 Trichomonas vaginalis
2 Lactobacilli
3 Staphylococci
4 Enterococci
5 Streptococci
Lactobacilli
The vaginal microbial flora is influenced by hormonal factors. The vaginas of newborn girls are colonized with lactobacilli at the time of birth. Lactobacilli predominate for approximately 6 weeks, after which the maternal, estrogen level declines and the vaginal flora changes to include staphylococci, streptococci, and Enterobacteriaceae.
The oral cavity is home to many species of normal flora. Among these are bacteria and other microorganisms, which can often include potential pathogens such as:
1 Staphylococcus epidermidis
2 Escherichia coli
3 Staphylococcus aureus
4 Candida albicans
Candida albicans
Candida albicans is often associated with mucosal membranes and has a high potential for pathogenesis. Escherichia coli is a coliform found in the gastrointestinal tract. Both Staphylococcus aureus and Staphylococcus epidermidis are normal flora of the skin that can be involved with wound infections and other pathologic states.
Cognitive Level: Understand
During childbearing years the normal flora of the healthy vagina contains large numbers of which type of bacteria?
1 Streptococcus species
2 Haemophilus species
3 Lactobacillus species
4 Staphylococcus species
5 Candida albicans
Lactobacillus species
The normal flora of the healthy vagina is strongly influenced by the hormonal background of the host. Hence differences occur between prepuberty, childbearing and post-menopausal flora. During the childbearing period, lactobacillus species predominate the bacteria present. Candida albicans is often associated with vaginal infections during this time, but these organisms are yeast and not bacteria. Staphylococcus species are associated with skin surfaces and can be pathogenic or not. The same can be said for Streptococcus species within the nasopharynx and oral cavity. Haemophilus species are principally associated with respiratory infections.
Which one of the following bacteria is carried by about 20% of women of child-bearing age and is a cause of sepsis and meningitis of the newborn?
1 Lactobacilli species
2 Bacteroides
3 Bifidobacterium
4 Group B streptococci
5 Clostridium
Group B streptococci
Group B streptococci are carried by about 20% of women of childbearing age in their vagina and are a cause of sepsis and meningitis of the newborn and are acquired during passage through the birth canal. Lactobacilli, Bacteroides, Bifidobacterium and Clostridium are normally found in the colon and do not cause sepsis and meningitis of the newborn.
If a patient has subacute endocarditis caused by the viridans strain of Streptococcus, the most likely source of the organism is the:
1 Colon.
2 Skin.
3 Vagina.
4 Urethra.
5 Oropharynx.
Oropharynx.
The viridans group of Streptococci are normally found in the oropharynx and often enter the bloodstream during dental procedures and cause endocarditis. The viridans group of Streptococci are usually absent in the colon, skin, vagina and urethra.
Which of the following are a major group of bacteria commonly associated with the skin that are normal flora but can become opportunistic pathogens?
1 Escherichia coli
2 Salmonella species
3 Staphylococcus species
4 Streptococcus species
5 Haemophilus species
Staphylococcus species
Staphylococcus species are common normal flora of the skin. Although most of these bacteria are non-pathogenic, Staphylococcus aureus is associated with wound infections. Escherichia coli is normal flora associated with the gastrointestinal tract; although some strains can be pathogenic, most are not. Salmonella species are not normal flora and many are associated with pathological conditions. Streptococcus species are normal flora of the mouth and nasopharynx. Several species are associated with opportunistic infections. Haemophilus species are also found in the nasopharynx but are commonly pathogenic.
An elderly woman was admitted to the hospital for a septic wound treatment on her lower abdomen, which developed after a perforated colon operation. Her wound was 1.5-cm open and oozing a yellow exudate. Which of the following groups of microorganisms is most likely contaminating this operation following this colon procedure?
1 Gram positive anaerobes
2 Gram negative anaerobes
3 Gram negative aerobes
4 Gram positive aerobes
5 Yeasts
Gram negative anaerobes
Most likely contaminating bacteria will be the normal flora of colon following a colon perforation. Anaerobic bacteria represent more than 90% of the colon flora. Gram negative anaerobes are the most numerous species in the lower gastrointestinal tract and can make up to 80% of the dry weight of fecal contents.
The most common microorganisms in the colon flora are:
Bacteroides (gram-negative anaerobic bacilli) are the predominant species in the colon in two-thirds of the population.
Bifidobacterium (gram-positive bacilli) species predominate in the remaining third.
Clostridium perfringens (gram positive bacilli) is present in small numbers, but can be found in virtually every normal individual.
Facultative organisms (e.g., Escherichia coli, enterococci) and yeasts constitute the remainder of the flora.
A 34-year-old woman visits her physician for a urinary tract infection. Her doctor gives her a course of antibiotic to clear up the infection. She comes back to see her doctor again complaining of severe irritation, itchiness and whitish cheesy discharge from her vagina following the antibiotic treatment. Which of the following is the most possible mechanism causing this vaginitis?
1 Increased pH due to decreased lactobacillus population
2 Increased pH due to increased lactobacillus population
3 Decreased pH due to decreased lactobacillus population
4 Decreased pH due to increased lactobacillus population
5 Overgrowth of yeast due to increased lactobacillus population
Increased pH due to decreased lactobacillus population
During the reproductive years, the most numerous species in the vagina is Lactobacillus. These organisms generate lactic acid and help maintain an acidic environment in the vagina. The low pH inhibits the growth of other types of microorganisms.
Following an antibiotic treatment lowers the Lactobacillus population, increasing the pH of vagina, favoring the multiplication of yeast and other bacteria. Yeast overgrowth is a particular problem because they are unresponsive to antibiotic treatments.
