Coccus

Tao Chuan-min Tel:85422618

E-mail:taochuanmin@sina.com.cn

Outline

Staphylococcus

Streptococcus

Enterococcus

Neisseria and Branhamella

Classification 、 Clinical Significance 、 Microbial

Characters 、 Microbial diagnostics

Staphylococcus Gram-positive cocci that occur singly and in pairs, tetrads, and irregular grape-like clusters

Common description Widespread in nature

Mainly found living on the skin, skin glands

and mucous membranes of mammals and

birds

Also found in the environment

Sometimes found in the mouth, blood, and

intestinal, and upper respiratory tracts

ClassificationCurrently composed of 32 species and 15 subspecies

Important StaphylococcusS. aureus

S. epidermidis

S. capitis

S. hominis

S. saprophyticus

CoagulaseCoagulase positive Staphylococci

Coagulase negative Staphylococci

Clinical significantS. aureus Important pathogen

Enzymes:catalase, coagulase,staphylokinase, et al Toxin: exotoxin, enterotoxin, et al

Community- and hospital acquired infection Acute pyogenic infection

Common infection ： boil 、 cellulitis 、 postoperative wound infections

Serious infection ： bacteremia 、 pneumonia 、 osteomyelitis 、 meningitis ， acute endocarditis, et al

BoilsInfection of hair follicles by S. aureusImpetigo

School sores; common mostly among children

Abscess

Osteomyelitis

Food poisoning: enterotoxinToxic shock syndrome(TSS) ：

toxic shock syndrome toxin 1(TSST-1)

Scaled skin syndrome

Coagulase negative staphylococcus, CONS Normal flora of human Causing nosocomial infections S. epidermidis

Prosthetic valve endocarditis

Intravascular catheter-related infection

Peritoneal dialysis-related infection 　　　　　　 Prosthetic joint infection

Why The increase in the use of prosthetic and indwelling devices Immunocompromised patients in hospitals

S. saprophyticus Urinary tract infection

Microbial CharactersGram positive coccus arranged ： single 、 pairs 、 tetrads, short chains and grape-like

clusters

Facultatively anaerobe

Colonial appearance Color, smooth, entire, heamolytic characters

Chemical reaction: active metabolism, fermenting carbohydrates

Catalase ： +(differentiates from streptococcus)

Coagulase: +/-

Microbial diagnostics

procedure

　　　　　　 specimen

Smear and stain culture 　 direct examination

　　　　　　　 colony

Smear and stain biochemical serology 　 antibiotic

identification 　 identification susceptibility

Isolated cultureBroth culture

Specimen collection Routine method

Avoid normal flora contamination Surface swab, pus, blood, spinal fluid,

sputum, et al

Specimen direct diagnostics Smear and Gram stain report

Culture and identification Media selection

Blood agar Broth Selective agar 　

Colonial appearance

S. epidermidis Small, smooth, entire, sli

ghtly raised, white, nonheamolysis

S. aureus Large,smooth,entire, sligh

tly raised, pigment from cream-yellow to orange, β heamolysis

Catalase

Staphylococcus produce catalase

Convert hydrogen peroxide into water and oxygen

(formation of bubbles)

Coagulase productionAbility to clot plasma

Rapid and economical test

Dehydrated rabbit plasma containing EDTA

Slide test Bound coagulase ＋ plasma 　　　 clot(10s)

+: S. aureus and S. intermedius

Tube test Free coagulase

Other: latex agglutination test

Heat-stable nuclease

+ ： S. aureus, S. schleiferi , S. intermedius and S. carnosus

Heat-stable staphylococcal nuclease (thermonuclease[TNase])

Method: metachromatic agar diffusion procedure and DNA-t

oluidine blue agar

Phosphatase activity

+ ： S. epidermidis, S. aureus, S. schleiferi and S. intermedius

Pyrrolidonyl arylamidase activity (PYR test)

principle:　　　　　　　　　　　　　 bacteria

L-pyrrolidonyl-β-naphthylamide 　　　　　　 β-naphthylamine

　　　　　　　　　　　　　　　 　＋

　　　　　　　　　　　　　　　　 N,N-dimethylaminocinnamaldehyde

　　　　　　　　　　　　　　　　　　　　 　 red color

OtherOrnithine decarboxylase activity

β-galactosidase activity

Novobiocin resistance

Antibiotic susceptibilities

A class （ routine antibiotic ）oxacillin,penicillin

B class （ use mainly antibiotic in clinical ）azithromycin,clindamycin,TMP/SMZ,vacomycin

C class （ resistant to A class ）ciprofloxacin,gentamicin,chloramphenicol

U class （ bacteria from urine ）norfloxacin, nitrofurantoin

Methecillin resistant Staphylococcus, MRS

MRSA 、 MRSE 、 MRSCO

Main pathogen in nosocomial infection

Resistant to oxacillin

resistant ： high resistant

heteroresistant ： borderline

Two subpopulations coexist: one susceptible and the other resist

ant

MRS

Detection methods

The presence of NaCl （ 2 to 4% ）cooler temperatures (30 to 35 )℃prolonged incubation(up to 48h)

mecA gene probe

PCR

MRS

Resistant mechanism chromosome mecA gene mediated, produce low affinity

penicillin binding protein(PBP), PBP2’ or PBP2a

characters

Multidrug-resistant

Resistant to all β － lactams

Clinical use

Vacomycin, teicoplanin, ciprofloxin, TMP-SMZ, et al

Summary

Gram stain ＋ colonial appearance 　　　　　

Catalase +

　　　　　　　　　　 + 　　　　 S. aureus

　　　　　　　　　　 _ 　　　　　　　　　　　　 coagulase 　　　　　 CONS

Attention: MRS