Sources and Normal Flora

Question 1

Eye

Answer 1

Coagulase negative staph and diphtheroids normally
Less commonly can have saprophytic Neisseria or viridans group strep

Typically the same flora as the skin but but the washing effect of eye secretions containing bacteriolytic enzymes limit the population of microorganisms found on the eye

Question 2

Ear

Answer 2

Coagulase negative staph and diphtheroids
Less frequently Bacillus, Micrococcus, saprophytic Neisseria, and mycobacteria
Normal fungi include Aspergillus, Alternaria, Penicillium, and Candida

External ear microbiota is pretty similar to that of the skin
Middle ear is normally sterile and protected by epithelium of eustachian tubes

Question 3

Nares (upper respiratory tract)

Answer 3

Staph aureus as well as normal flora of the skin

Question 4

Nasopharynx (upper respiratory tract)

Answer 4

Similar flora of the mouth
Site of carriage for potentially pathogenic bacteria like Neisseria meningitidis, Streptococcus pneumoniae, and Haemophilus influenzae

Question 5

Middle Ear (upper respiratory tract)

Answer 5

Normally sterile and protected by epithelium of eustachian tubes (tubes that connect middle ear to the nasal-sinus cavity)

Question 6

Mouth

Answer 6

Changes as people mature from babies to adults
For the first couple months the mouth is dominated by streptococci as well as some Neisseria, Veilonella, Lactobacillus, and Candida
As dental plaque forms Actinomyces, Bacteroides, Capnocytophaga, and Eikenella start to take over
With hormonal changes in teens and young adults, Prevotella increases as Actinomyces and Capnocytophaga decrease
Healthy adults have around 200 Gram positive and Gram negative bacterial species in their mouths

Question 7

Urethra

Answer 7

Enterobacteriaceae (usually E. coli), Lactobacillus, diphtheroids, alpha and non-hemolytic strep, enterococci, coagulase negative staph, Staphylococcus, Peptostreptococcus and Bacteroides spp.
Mycoplasma hominis, Ureaplasma urealyticum, Mycobacterium smegmatis, and Candida spp can also be recovered

The only portion of the urinary tract that harbors normal flora is the distal 1-2 cm of the urethra, the rest should be sterile

Question 8

Vagina

Answer 8

Saprophytic organisms like diphtheroids, micrococci, nonhemolytic strep, and Lactobacillus

Normal flora varies according to hormonal influences at different ages

Question 9

Esophagus

Answer 9

Normal mouth and nasal flora are common to occur in the esophagus
Unknown if these organisms represent transient colonization or if they are an established microflora