The most common bacterial pathogens isolated from patients in local hospitals are gram-negative bacilli and gram-positive cocci. Using the Kirby-Bauer sensitivities and multi-strip identification kits like enterotube, the most comon gram-negative lactose fermentors are E. coli, Proteus, and Klebsiella. These gram-negative rods are causes of about 40% of nosocomial infections (long term use of Foley catheter is major reason). Another gram negative bacillus isolated from burn patients and immunosuppressed patients is Pseudomonas.

The primary gram-positive cocci found in local patients are Staphylococcus and Streptococcus. Using media like PEA, mannitol salt agar, and blood agar, Staphylococcus and Streptococcus can be identified. Pathogenic Streptococcus is hemolytic and catalase negative (no bubbles from hydrogen peroxide) and can be confirmed by a gram stain (noting chains of gram- positive coccus).Staphylococcus is catalase positive and will often grow on the high salt Mannitol Salt Media with yellow zones aroung the white colonies. Staphylococcus is one of the known nosocomial microbes isolated form surgical patients. Other pathogens isolated from local patients include anaerobes (Clostridium, Bacteroides, and Eikinella), fastidious bacteria (Neisseria, Treponema, and Haemophilus), and opportunistic yeast (Candida). When handling potential pathogens, you must practice universal body substances precautions (UBSP) and recognize that many pathogens are develooping resistance to antibiotics. Vancomycin resistant enterococci (VRE) and methicillin resistant Staph aureus (MRSA) require that new antibiotics be developed and used. The drug cephazolin is one antibiotic with potential inhibiting effects.