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Staphylococci
 Facultative, non-sporulating, non-motile, Gram positive
cocci
 Cell Division  3 planes
– Daughter cells don’t fully separate  form clusters
 Greek nouns
– Staphyle – “ a bunch of grapes
– Coccus – “grain or berry”

Disease Manifestations due
to Staphylococcus aureus
 Skin and soft tissue
infections
 Impetigo

 Osteomyelitis

 Endocarditis
 Septic phlebitis
 Catheter infections

 Toxic shock syndrome
 Septicemia


Disease Manifestations due
to Staphylococcus aureus
 Skin and soft tissue
infections
 Impetigo
 Cellulite
 Osteomyelitis
 Pneumonia
 Endocarditis
 Septic phlebitis
 Catheter infections
 Surgical site infections
 Toxic shock syndrome
 Septicemia
 Septic arthritis

Staphylococci
27 species  Three Important Species
 Staphylococcus aureus
– Important human pathogen
 Staphylococcus epidermidis
– Normal skin flora, disease under special circumstances
 Staphylococcus saprophyticus
– UTI’s in young females

S. aureus - Epidemiology
 Reservoir – Humans
 Asymptomatic Carriage Sites:
–
–
–
–
 Skin Colonization - Brief, Repeated
 Transmission -

S. aureus - Epidemiology
 Reservoir – Humans
 Asymptomatic Carriage Sites:
– Nares
– Rectum
– Perineum
– Pharynx
 Skin Colonization - Brief, Repeated
 Transmission - Person to Person

S. aureus Carriage Rates
Population Carriage Rate (%)
General Population 25
Hemodialysis 75
Diabetic on insulin 50
Patients receiving 50
allergy shots
Intravenous Drug Users 40

Staphylococcal Infections - Risk Factors
 Skin Disease
– Increased colonization
 Trauma
– Expose binding sites
 Viral Respiratory Tract
Infection (Influenza)
– Expose binding sites
– Decreased clearance
 Foreign Body
 Liver disease
 Neoplasia
 Diabetes
 Renal Failure
 Leukocyte &
Immunoglobulin Defects
 Elevated Serum IgE
Levels
 Narcotics Addiction
 Broad Spectrum Antibiotic
Therapy
In general  Healthy people don’t get serious Staph infections

Patterns of Disease - S. aureus
1) Invasion with Tissue Destruction
2) Toxin Mediated
–
–
–

Patterns of Disease - S. aureus
1) Invasion with Tissue Destruction
2) Toxin Mediated
– Toxic Shock Syndrome
– Scalded Skin Syndrome
– Staphylococcal Food Poisoning

Anterior Nares
Skin Trauma Localized
Colonization Infection
Bacteremia
Metastatic
Foci
Lungs
Endocarditis Liver/Spleen
CNS
Kidneys

Folliculitis
 Starts as
infection of hair
follicle 
Folliculitis

 A 22-month-old boy with a
staphylococcal folliculitis on the buttocks.
The lesions have been excoriated. Diaper
occlusion may have been related to onset
of the rash.

Furuncle
 Often starts as infection of
hair follicle  Folliculitis
 Firm, tender red nodule 
Painful
 Fluctuant with time  Drain
spontaneously

Carbuncle
Larger than furuncle
 Extends into
subcutaneous fat
 Interconnected
 Firm, inelastic skin

Impetigo
• The most common skin infection in
children.
• Causative agent is carried in the nasal area.
• Bacteria invade the superficial skin.

Impetigo
 Superficial infection of skin
 Usually
– S. aureus
– Streptococcus pyogenes
 Children
 Hot Weather
 Minor Trauma
 Initially  vesicles

Impetigo
 Later: Crusted with
yellow  dark brown
material

Interventions
•Good general hygiene
•Wash gently with soap and water
•Topical antibiotic therapy
•Wash hands
•Systemic antibiotics only if severe
and does not respond to topical.
(keflex po)

Erysipelas
 Strep pyogenes or S.
aureus
 Sharp, raised borders

Erysipelas
Streptococcal Skin Infections

Cellulitis
 A full-thickness skin infection
involving dermis and underlying
connective tissue.
 Any part of the body can be
affected.
 Cellulitis around the eyes is usually
an extension of a sinus infection or
otitis media.

Cellulitis
 Acute, spreading
Infection
 Prior trauma to skin
 Warm and
erethematous

Assessment
 History and physical exam
 WBC count
 Blood culture
 Culturing organism from lesion
aspiration.
 CT scan with peri-orbital cellulitis

Clinical Manifestations
 Characteristic reddened or lilac-
colored, swollen skin that pits when
pressed with finger.
 Borders are indistinct.
 Warm to touch.
 Superficial blistering.

Periorbital swelling and Fever after dental abscess

Imaging Air, edema and collection in orbital
cavity
More than ½ of orbit is anterior to orbital cavity
(proptosis)
Bilateral Ethmoid
sinusitis

Bilateral Maxillary
sinusitis
Bilateral Ethmoidal
sinusitis
Soft tissue swelling and
edema

Bilateral Maxillary
Bilateral Ethmoidal
sinusitis
Soft tissue swelling ,
edema & collection
intraorbital cavity
Congested Nasal
conchea

Interventions
 Hospitalization if large area involved
or facial cellulitis.
 IV antibiotics.
 Pain management.
 Warm moist packs to area if ordered.
 Assess for spread
 If peri-orbital test for ocular
movement and vision acuity

Epiphysis
Marrow
Cartilage
Cortex
Epiphyseal plate
Capillary loop
Micro-abscess
Cortex
Periosteum
Marrow
Bone trabeculae
Metaphysis
Pyogenic osteomyelitis -pathogenesis

Cortex
Abscess
Periosteal reactive bone
Bone resorption: osteoclast
Organisation: fibrosis
Trabeculae
New reactive bone: osteoblasts

Expansion of abscess
Periosteal elevation
Shearing of arteries
Subperiosteal
abscess
Reactive bone
Ischemia = osteonecrosis (sequestrum)

Pus in joint
Extension into soft tissue
Draining sinus
Skin
Cortical necrosis =
sequestrum
Reactive bone surround
sequestrum: involucrum
Continuous resorption
Continuous new bone
and fibrosis of marrow
sequestrum

TOXIC SHOCK SYNDROME
 Acute Febrile Illness
 Subsequent Development of Hypotension
and Shock.
 Noted association with S. aureus phage
group I
 Named the illness "Toxic Shock Syndrome“

TOXIC SHOCK SYNDROME
1990 - More than 3,300 cases have been
reported
 95% in women
 90% occurred during menstruation in
women who were using tampons
1989 - 61 cases of TSS reported

Toxic Shock Syndrome -
Epidemiology
1. Menstrual
 Colonization of the Vagina and Cervix
with TSST-1 producing strains of S.
aureus
– Tampon Associated
• Risk proportional to the absorbancy of Tampon
– Not tampon associated

Epidemiology
2. Non-menstrual
 Post-surgical
 Influenza associated
 Contraceptive device associated
– Diaphragm
– Sponge
 Postpartum

Pyrogenic Toxin
 Family of Proteins secreted by
– S. aureus
– Strep pyogenes
 Include
– TSST-1
– Staphylococcal Enterotoxins A, B,C
– Pyrogenic Exotoxin A & B
– Streptococcal Scarlet Fever Toxins A, B,C

Toxic Shock Syndrome
- Clinical Manifestations
1. High Fever (>39.9oC)
2. Scarlatiniform Eruption
3. Hypotension and Shock
4. Desquamation during
convalescence

Staphylococcal toxic shock
syndrome
Toxic shock syndrome (TSS)
Toxic shock syndrome toxin
(TSST-1)
Super antigen
Tampon or infected wound, TSST-
1 enters blood stream and cause
fever, rash, exfoliation of skin and
shock (death rate 3%)

Manifestations of Specific Organ
Involvement
 Mucous Membranes: hyperemia
 Gastrointestinal Tract: vomiting and diarrhea
 Muscle: severe myalgias
 Central Nervous System: disorientation
 Kidney: azotemia, pyuria urinary tract infection
 Liver: elevation of serum bilirubin and SGOT
 Blood: Thrombocytopenia

Diagnosis
• Isolation of toxin producing S. aureus
from a patient with a compatible
clinical illness.

Treatment
1) Treatment of Hypotension and Shock
– Vigorous Fluid Replacement
2) Attention to the Site of S. aureus Colonization
– Removal of Tampons
– Drainage of Staphylococcal Abscess
3) Anti-Staphylococcal Antibiotic Therapy

STAPHYLOCOCCAL SCALDED SKIN SYNDROME
 A Disease of Infants
– Localized Infection with Diffuse Skin Rash
 S. aureus (Phage group II) recovered from:
– Nose
– Pustules
– Eye
– Umbilicus
 Exfoliative Toxin
– Two Serologically and Biologically Distinct Proteins
• Exfoliatin A
• Exfoliatin B
– Inter-Epithelial Splitting of Stratum Granulosum Layer

Staphylococcal Scalded Skin Syndrome -
Clinical Features
 Starts Abruptly
– Perioral erythema
– Sunburn like, tender rash 
spreads over entire body
 Bullae Appear Rapidly
– Nikolsky sign
– Flaccid bullae slough off 
Denuded areas

Staphylococcal Scalded Skin Syndrome -
Clinical Features
 Exfoliated Areas Eventually Dry
– Flaky desquamation lasting 3-5
days
 Within 10 days After Onset
Complete Recovery
– New epidermis has replaced the
denuded areas

Scalded skin syndrome – toxin

Staphylococcal scalded skin syndrom (SSSS)
Exfoliative toxin (epidermolytic toxin)
Bullous exfoliative dermatitis

Staphylococcal Food Poisoning
 20% of Outbreaks of Acute Food
Poisoning
 Toxigenic Strain of S. aureus growing in
contaminated food
– Produces Enterotoxin B (Heat Stable)
 Person to Person Transmission
– Responsible organism usually isolated from person
involved meal preparation

Staphylococcal Food Poisoning
 Commonly implicated foods
– Custard filled bakery good
– Canned food
– Potato salad
– Ice cream
 Food appears normal in
appearance, odor and taste

Staphylococcal Food Poisoning -
Clinical Features
 Incubation period 2-6 hours
 Enterotoxin stimulates intestinal
peristalsis and CNS
– Abrupt onset:
• Salivation
• Nausea and vomiting
• Abdominal cramps
• Watery diarrhea
 Afebrile
 Self limited, symptoms disappear in 8 hours

S. aureus
Evolution of Drug Resistance in S. aureus
Methicillin
[1970s]
Methicillin-
resistant
S. aureus (MRSA)
S. aureus
Penicillin
[1950s]
Penicillin-resistant
Vancomycin-resistant
enterococci (VRE)
Vancomycin
[1990s]
[1997]
Vancomycin
intermediate-
resistant
S. aureus
(VISA)
[ 2002 ]
Vancomycin-
resistant
S. aureus

Bone5:
7%–13%
Vancomycin Penetration
Sternal Bone1:
57%
Heart Valve4:
12%
CNS:
<10%
Fat4:
14%
Muscle4:
9%
Epithelial
lining fluid3:
18%
Lung tissue2:
17%–24%
1. Massias L et al. Antimicrob Agents Chemother. 1992;36:2539-2541; 2. Cruciani M et al. J Antimicrob
Chemother. 1996;38:865-869. 3. Lamer C et al. Antimicrob Agents Chemother. 1993;37:281-286;

MRSA in Europe.
In England and Wales, from
January to December 1999
methicillin resistance was
37% of the S.aureus reports.
Except Scandinavia and
Netherlands most countries
have high rates of MRSA.

0
10
20
30
40
50
60
1
9
7
5
8
7
8
8
8
9
9
0
9
1
9
2
9
3
9
4
9
5
9
6
9
7
9
8
9
9
2
0
0
0
2
0
0
2
Resistant
isolates
(%)
CDC. MMWR. 1997;46:624-628, 635. (1975 data); Lowy FD. N Engl J Med. 1998;339:520-532.
Progression of Methicillin Resistant
S aureus – United States 13%



Staphylococcus aureus
(N0=224)
CD
ER
LZD
PG
TS
RP
OX
CIP
C
KF
AK
T
VA
QD
GM
FU
R 53
(24)
80
(36)
4
(2)
215
(96)
92
(41)
20
(9)
78
(35)
72
(32)
5
(2)
71
(32)
70
(31)
102
(45)
0
(0)
0
(0)
72
(32)
8
(4)
S 170
(76)
130
(58)
220
(98)
9
(4)
131
(58)
203
(90)
146
(65)
148
(66)
218
(97)
151
(67)
150
(68)
122
(55)
224
(100)
224
(100)
152
(68)
216
(96)
IR 1
(0.5)
14
(6)
0
(0)
0
(0)
1
(.5)
1
(.5)
0
(0)
4
(2)
1
(.5)
2
(1)
3
(1)
0
(0)
0
(0)
0
(0)
0
(0)
0
(0)
CD=Clindamycin, ER=erythromycin, LZD=linezolid, PG=PenicillinG, TS=Co-trimoxazol, RP=Rifampin,
OX=Oxacillin, CIP=Ciprofloxacin, C=Chloramphenicol, KF=Cephalothin, AK=Amikacin, T=Tetracycline,
VA=Vancomycin, QD=Quinupristin-dalfopristin, GM=Gentamycin, FU=Fusidic acid

Reservoir for the Spread of
Antibiotic Resistant Pathogens
clinical
infections
colonized
(asymptomatic)

Standard Precautions for Health
Care workers include:
 Hand hygiene / handwashing- before and after
patient contact and after touching contaminated
items
 Gloving - when touching blood, body fluids,
secretions, excretions,and contaminated items
 Masking – if aerosol of infectious material
expected
 Gowning
 Appropriate handling of laundry

Most common mode of
transmission of pathogens is via
hands!
So Why All the Fuss About
Hand Hygiene?

The Inanimate Environment Can
Facilitate Transmission
~ Contaminated surfaces increase cross-transmission ~
Abstract: The Risk of Hand and Glove Contamination after Contact with a
VRE (+) Patient Environment. Hayden M, ICAAC, 2001, Chicago, IL.
X represents VRE culture positive sites

Staphylococcus epidermidis
 Normal Flora
– Virtually all humans carry S. epidermidis on the skin
and in and around body orifices
 Hospital Acquired Infection
– Contamination by S. epidermidis carried by the patient
• most important event in infections associated
with foreign bodies

Staphylococcus epidermidis
• opportunistic infection
- less common than S.aureus
• nosomial infections
- shunts, catheters
• artificial heart valves/joints

S. epidermidis - Patterns of Infection
 Nosocomial Bacteremia -most common cause
 Endocarditis
A. Native Valve
– Uncommon- 5% of cases
B. Prosthetic Valve
– Single most common cause (40% of cases)
– Probably caused by inoculation at the time
of surgery
– Indolent course

S. epidermidis - Patterns of Infection
 Intravenous Catheters
-Single most common cause (50-75% of cases)
 Cerebrospinal Fluid Shunts
 Peritoneal Dialysis Catheter
 Vascular Grafts
 Prosthetic Joints

S. epidermidis Infection -
Treatment
1. Antimicrobial Therapy
 Usually resistant to multiple antibiotics
– Beta lactams
– Erythromycin, Clindamycin, Tetracycline
 Require therapy with Vancomycin
2. Removal of Foreign Body

Staphylococcus saprophyticus
 Colonizes the genitourinary mucosa of some young
women
 Causes both upper and lower urinary tract disease
– 95% of cases are in females 16-35 years old
– Responsible for 20% of the UTI's in this age group
• Second only to E. coli
 Pathogen of young, sexually active females
– 70% sexual intercourse within 24 hours preceding onset of
symptoms

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