Summary Comprehensive Study of Staphylococcus: Laboratory Diagnosis, Virulence Factors, and MRSA Detection

Staphylococcus
Introduction

Staphylococcus is a group of Gram-positive bacteria commonly found on the skin and in the
nose of humans. While many species are harmless, some can cause serious infections.

Morphology

 Gram-positive cocci (round-shaped bacteria)

 Arranged in clusters (grape-like appearance)

 Non-motile.

 Facultative anaerobes (can survive with or without oxygen)

 Catalase-positive

Important Species

 Staphylococcus aureus – most pathogenic, causes many infections.

 Staphylococcus epidermidis – part of normal skin flora, opportunistic.

 Staphylococcus saprophyticus – causes urinary tract infections.

Diseases Caused

 Skin infections (boils, pimples, abscesses)

 Food poisoning

 Pneumonia

 Blood infections (sepsis)

 Toxic shock syndrome

Transmission

 Direct contact with infected person

 Contact with contaminated surfaces

 Through cuts or wounds

, Laboratory Diagnosis of Staphylococcus

1. Specimen Collection

The type of specimen depends on the site of infection:

 Pus / wound swab → skin infections, abscess

 Blood → suspected septicemia

 Sputum → pneumonia

 Urine → urinary tract infection

 Nasal swab → carrier detection

Procedure:

 Collect samples using sterile techniques

 Use sterile swabs or containers

 Transport immediately to the laboratory

Avoid contamination

2. Direct Microscopy

Gram Staining:

 Smear is prepared from specimen

 Stained using Gram stain

Result:

 Purple (Gram-positive) cocci

 Arranged in grape-like clusters

This gives a preliminary identification.

3. Culture

Media used:

 Blood agar

 Nutrient agar

 Mannitol salt agar (selective medium)