Lab 3 Continuation of Stains

Gram Unknown Each student gets one unknown tube of bacteria Gram stain and record –Your name –Unknown number –Gram reaction (positive or negative) –Morphology –Arrangement

Capsule Stain Another negative stain Use K. pneumoniae Pg 96

Endospore Stain An endospore is a dormant form of a bacteria. If a bacteria is capable of producing endospores, it does so when environmental conditions are poor Steam is used to help stain penetrate the cell wall Stain B. cereus using procedure on page 99.

Acid-fast Stain Takes advantage of mycolic acid in the cell wall of slow growing mycobacterium Use M. smegmatis and S. aureus on the same slide using Ziehl-Neelsen method (pg 93)

Klebsiella pneumoniae Gram Negative Non-motile Rod shaped – bacilli Enterobacteria Causes Klebsiella pneumonia and urinary tract infections Pneumonia often found in alcoholics and UTI in older people

Bacillus Cereus Gram Positive Rod shaped – bacilli Can produce endospores Can cause foodborne illnesses –Diarrheal type syndrome –Emetic (vomiting) type syndrome Can cause skin infections that are difficult to eradicate Can cause keratitis (inflammation of cornea)

Mycobacterium Smegmatis Acid-fast bacteria Mostly considered a non-pathogenic organism Named for a similar organisms found in smegma (genital secretions)

Staphylococcus aureus Gram-positive Spherical – cocci “the golden cluster seed” Most common form of staph infections Frequently part of skin flora found in the nose and on the skin 20% of population are long-term carriers

Staphylococcus aureus – cont. –Pneumonia –Meningitis –Osteomyelitis –Endocarditis –Toxic shock syndrome –Septicemia –Post-surgical wound infections Causes: –Minor skin infections such as pimples –Impetigo –Boils –Cellulitis folliculitis –Furuncles –Carbuncles –Scalded skin syndrome –Abcesses

Methicillin-resistant S. aureus MRSA Endemic in hospitals Spread by human – to – human contact Resistant to penicillin Must be treated by specialized antibiotics