Bacteriological Analysis of Normal Flora of Skin, Nasal

and Ear Specimens

Sonia Akhtar, Xia Mujahid, Sobia Ishaque and Fareeha

26 April, 2012

Introduction: The human microbiome (or human microbiota) is the

aggregate of microorganisms that reside on the surface and in deep layers of skin, ear, in the saliva and oral mucosa, in the conjunctiva, and in the gastrointestinal tracts. They include bacteria, fungi, and protozoa. Some of these organisms perform tasks that are useful for the human host. Those that are expected to be present, and that under normal circumstances do not cause disease, but instead participate in maintaining health, are soul members of the normal flora.

It is estimated that 500 to 1000 species of bacteria live in the human gut and a roughly similar number on the skin.Bacterial cells are much smaller than human cells, and there are at least ten times as many bacteria as human cells in the body (approximately 1014 versus 1013).Though members of the flora are found on all surfaces exposed to the environment (on the skin and eyes, in the mouth, nose).

Different harmless microorganisms establish as commensals or mutualistic with the host.

Normal flora can be divided into two groups, residential flora and temporary flora.

The normal flora as well as host immune status both do not allow to infect the host.

The environmental conditions like pH, temperature, availability of oxygen, presence of moisture etc also influence their presence.

Aim: The basic aim of this study was to analyze the normal flora of Skin, Nose and Ear

Materials and Methods:

Samples of nose , ear & skin were collected by the normal healthy individuals by the help of swabs in aseptic conditions.

Media: which were used are nutrient agar, sheep blood agar, MacConkey agar, Manitol salt agar, Muller Hinton Agar and Salt Indol Motility agar.

Table 1. Colonial morphology, microscopic examination and hemolysis

SPECIMEN BLOOD AGAR MACCONKEY AGAR NUTRIENT AGAR GRAM REACTION MOTILITY

EAR 1 γ hemolysis Colorless colonies Small, rounded, opaque colonies

Gram positive cocci

Non-motile

EAR 2 β hemolysis Colorless colonies Small, rounded, golden yellow colonies

Gram positive cocci

Non-motile

NASAL 1 β hemolysis Colorless colonies Small, rounded, opaque colonies

Gram Negative diplococci

Non-motile

NASAL 2 β hemolysis Large, shiny, mucoid , pink colonies

Large, opaque colonies Gram Negative bacilli

Non-motile

SKIN 1 β hemolysis Colorless colonies Small, rounded, opaque colonies

Gram positive cocci

Non-motile

SKIN 2 γ hemolysis Colorless colonies Small, rounded, opaque colonies

Gram positive cocci

Non-motile

Table 2. Biochemical tests for Gram negative isolates

SPECIMEN TSI IMViC UREA LACTOSE ORGANISM

NASAL 2Butt Slant H2S Gas I MR VP C

+ve +ve Klebsiella pneumoniaeAcid Acid +ve -ve -ve +ve +ve +ve

Gram negative isolated colonies showing lactose fermentation and mucoid growth on Macconkey agar plate

TSI and Citrate results of Gram negative bacilli isolated from nasal specimen no.2

Table 3. Biochemical testsSPECIMEN GRAM

REACTION

UREA CAT. OXI. COAGULASESUGARS Organism

identifiedlac suc mal men

EAR 1Gram positive

cocci+ - + - + + + - Streptococcus viridans

EAR 2Gram positive

cocci - + - + + + - Staphylococcus aureus

NASAL 1Gram Negative

diplococci - + + - + + + - Niesseriaspp.

NASAL 2Gram Negative

bacilli + - + - + + + - Klebsiella pneumoniae

SKIN 1Gram positive

cocci- - + - + + + - Streptococcus epidermidis

SKIN 2Gram positive

cocci- - + - + + + - Streptococcus epidermidis

Table 4. aaantibiotic succeptibility

Culture codesAntibiotics

P Cl S Amp Be

EAR 1 - - - - -

EAR 2 3mm 6mm 9mm 1mm 2mm

NASAL 1 - - - - 2mm

NASAL 2 - - 2mm - -

SKIN 1 12mm 10mm 6mm 6mm 2mm

SKIN 2 11mm 10mm 5mm 6mm 3mm

Antibiotic susceptibility Isolated pure cultures from specimens

RESULTS:

The Ear specimens 1 and 2 were identified as Streptococcus viridans and Staphylococcus aureus

Nasal specimens 1 and 2 were identified as Niesseria spp.and Klebsiella pneumoniae

Nasal specimens 1 and 2 were identified as Niesseria sp

Non of the isolated organisms showed sensitivity against antibiotics

DISCUSSION:The varied environment of the skin results in locally

dense or sparse populations, with Gram-positive organisms (e.g., staphylococci, micrococci, diphtheroids) usually predominating.

S. epidermidis is a major inhabitant of the skin, and in some areas it makes up more than 90 percent of the resident aerobic flora.

Streptococci, especially β-hemolytic streptococci, are rarely seen on normal skin. The paucity of β-hemolytic streptococci on the skin is attributed at least in part to the presence of lipids on the skin, as these lipids are lethal to streptococci.

Gram-negative bacteria make up a small proportion of the skin flora.Gram-negative bacteria, is more common in the moist intertriginous areas.

• The nose and perineum are the most common sites for S. aureus colonization, which is present in 10 percent to more than 40 percent of normal adults. S. aureus is prevalent (67 percent) on vulvar skin. Its occurrence in the nasal passages varies with age, being greater in the newborn, less in adults. S. aureus is extremely common (80 to 100 percent) on the skin of patients with certain dermatologic diseases such as atopic dermatitis, but the reason for this finding is unclear.

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