MICRO: CH 14 Staphylococcus, Micrococcus and similar organisms

Micrococcus luteus produces a yellow pigment and is susceptible to

bacitracin

extracellular enzymes that inactivates several classes of antibiotics

beta lactamase

When should the tech should look for small colony variants (SVCs)

in persistent;, recurring infections;. if there are cocci in the gram stain;, but no growth on plates;. in presence of 2 colony types in positive blood cultures;. or in vitro activity shows susceptibility;. but treatment fails

Staph epidermidis is associated with

indwelling devices and prosthetics;. such as pertoneal dialysis catheters and valve endocarditis

Some strains of MRSA have become resistant to vancomycin; two new antibiotics that may be useful are

linezolid and daptomycin

Staph epidermidis; & other coagulase negative staph; have been dismissed as contamination; but may be

pathogenic

Oxacillin can destroy extracellular staph organisms but cannot

penetrate the host cell.

Daptomycin is the only negatively charged

antibiotic in use

Staph saprophyticus is differentiated from other nonhemolytic;, Cons (coag-neg staph) by its

resistance to novobiocin

Mannitol salt agar contains

10% salt mannitol; and pheno red as an indicator

Methicillin resistant Staph aureus is a multidrug resistant strain called

MRSA; which can only be treated with vancomycin

Micrococcus has two species

Micrococcus luteus and Micrococcus lylae; which are harmless saprophytes

Confirmation of oxacillin resistance in Staph aureus is done by testing for the presence of

Penicillin binding protein

Staph produce conlonies surrounded by a yellow halo. Species include

Staph aureus;. S. saprophyticus;. S. lugdunesis;. S. epidermidis;. S. haemolyticus;. and S. schleiferi

Endocarditis and soft tissue infections are associated with

Staph lugdumensis and Staph haemolyticus

In the family Micrococcaceae are the genera

Staphylococcus and Micrococcus

Staphs intrinsic resistance to beta lactam antibiotics is due to

a penicillin binding protein called PBP

Staph epidermidis produces exopolysaccharide slime;. which allows

adherence to the indwelling devices or prosthetics

test that detects cytochrome oxidase

catalase test

Staph aureus is differentiated from other species with a negative P Y R; and its production of

coagulase ; which is positive for the Voges Proskauer test;

Micrococci and staph contain

cytochrome enzymes; which is detected by catalase

Conditions that predispose a person to staph infections include

diabetes;. IV;. prosthetics;. chemotaxis disease; such as Chediak-Higashi;, neutrophil defects;. and complement defects

Toxic shock syndrome is a life threatening infection involving several organ systems that presents with

high temp;. diarrhea;. high blood pressure;. rash with desquamation;. and renal failure

Staph aureus is the most virulent species;. and Most staph secrete

enzymes and cytotoxins

Enzymes and cytotoxins secreted by staph include one of the 4

hemolysins;. nucleases;. proteases;. lipases;. hyaluronidase;. and collagenase

Chlorehexidine showers may be used to reduce Staph aureus colonization in

nasal pathways;. in situations of nasal carriers

Characteristics of staph

nonmotile; non spore forming; facultative anaerobes; and resistant to bacitracin.

Enzymes & cytotoxins secreted by staph convert host tissue into

nutrients required for growth

Staphylococcus and Micrococcus cocci are gram

positive

sloughing of epidermis usually seen in neonates

scalded skin syndrome

Staph lugdunesis and Staph schleifer are Cons isolated from colonized

shunts; prosthetic devices and catheters

Saprophytes inhabit

skin; mucosa; and oropharynx

The most common cause of food poisoning

staph aureus enterotoxin contamination

Some strains produce exoproteins; including TSS-1; which causes

toxic shock syndrome

Staph saprophyticus is a true

urinary tract pathogen

Small colony variants (SCVs) can evade destruction & proliferate; by hiding

within the host cell

Are staph able to grow in the presence of salt

yes.; This characteristic is used to isolate staphylcocci from clinical material.

Staph saprophyticus cause upper and lower UTI in

young; sexually active females