Loading presentation...

Present Remotely

Send the link below via email or IM

Copy

Present to your audience

Start remote presentation

  • Invited audience members will follow you as you navigate and present
  • People invited to a presentation do not need a Prezi account
  • This link expires 10 minutes after you close the presentation
  • A maximum of 30 users can follow your presentation
  • Learn more about this feature in our knowledge base article

Do you really want to delete this prezi?

Neither you, nor the coeditors you shared it with will be able to recover it again.

DeleteCancel

Staphylococci

No description
by

mariam kavtaria

on 30 September 2018

Comments (0)

Please log in to add your comment.

Report abuse

Transcript of Staphylococci

gram positive cocci
Catalase test
Staphylococci
Streptococci
Coagulase/Protein A
+
_
S. aureus
Coagulase negative staph
Novobiocin
Resistant
Susceptible
S. epidermidis
S. Haemoliticus
S. Hominis
S. Lugdunensis
S. Schleiferi
S. Saprophyticus
S. Xylosus
-
+
S. aureus produces 3 types of toxin:
predisposing factors :
chronic skin conditions (e.g., eczema)
skin damage
injections (diabetes, injection drug use)
poor hygiene

X-rays may be normal for up to 14 days
99mTc-phosphonate scanning detects early infection


respiratory
Nosocomial
S. aureus pulmonary infections - seen in
intubated
patients
Community-acquired respiratory tract infections -
usually follow viral infections
—most commonly
influenza.
Bacteremia and Endocarditis
Transesophageal echocardiography - more invasive
Transthoracic echocardiography - less sensitive
Toxin-producing S. aureus
into food
- colonized by food handlers
Toxin is elaborated in food as
custards, potato salad, or processed meats.
Toxin is
heat stable
Survives conditions that kill the bacteria.
Ingestion of preformed toxin

Short
Incubation period
(1–6 h)
.

The skin is
fragile and tender
,
thin-walled, fluid-filled
bullae
Nikolsky's sign
- Gentle pressure results in rupture of the lesions, leaving denuded underlying skin
Coagulase - Negative Staphylococcus
Elaborates the
extracellular polysaccharide
(glycocalyx or slime)
Forms the
biofilm

on the device surface.
Biofilm
- protects bacteria from WBCs and antibiotics
Provides a suitable
environment
for bacterial survival
ANTIBIOTICS:
Penicillin sensitive:
Penicillin G
only <5% of isolated strains are susceptible
Methicillin sensitive:

Oxacillin
Cloxacillin
Dicloxacillin
Nafcillin
Methicillin resistant (MRSA):
Vancomycin
Staphylococcal infections
Gram Positive Cocci
Staphyle -
bunch of grapes
Kokkos -
berries
The most common cause of
surgical wound infections
.
Enzymes:
Serine Proteases, Hyaluronidases, Thermonucleases, Lipases. They facilitate survival and local spread.
S. AUREUS:
Forms grapelike clusters on Gram's stain
Non - motile
Catalase +
Coagulase + (converts fibrinogen to fibrin)
Is a part of the
normal human flora;

Protein A,
unique to S. aureus, binds the
Fc portion of IgG -
prevents opsonization and phagocytosis by PMNs.
Skin and Soft Tissue Infections
Toxic Shock Syndrome Toxin 1
(TSST-1)
Cytotoxin
Exfoliative Toxin
Toxic Shock Syndrome Toxin 1 (TSST-1)

REASON:
use of a highly absorbent tampon that had recently been introduced to the market.

Superantigen
-
excessive activation of immune cells
Massive release
of inflammatory cytokines:
interferon alfa , IL-1, IL-6, TNF-alfa
damage to almost all tissues - Multisystem failure and shock;
1. Fever:
temperature of 38.9°C
(102°F)
2.
Systolic blood pressure < 90 mmHg
, or
orthostatic hypotension

3. Diffuse
macular
rash
, with
desquamation in 1–2 weeks

4. Multisystem involvement:
Hepatic:
bilirubin or aminotransferase levels 2 times normal,
Hematologic
: platelet count < 100,000/L,
Renal:
blood urea nitrogen or creatinine level 2 times the normal upper limit
Mucous membranes:
vaginal, oropharyngeal, or conjunctival hyperemia,
GI:
vomiting, diarrhea
Muscular
:
myalgias
, serum
creatine phosphokinase
2X the upper limit,
CNS:
disorientation, alteration in consciousness
5.Negative cultures for organisms other than S. aureus
Supportive therapy; reversal of hypotension - mainstay of therapy for TSS.
The Enterotoxins
Disease
Treatment - Supportive
The toxin stimulates vomiting center of the brain and peristaltic activity
Nausea
Vomiting
Diarrhea
Hypotension
Dehydration
Carbuncles
-
coalescence of other lesions;
even more severe and painful, extend
to
deeper layer of the subcutaneous tissue
.
Folliculitis
- superficial infection of
hair follicles
, with a
central area of purulence
(pus) surrounded by erythema.
Furuncles (boils) -
Larger, painful lesions - at hairy, moist regions of the body.
BONE INFECTIONS
Osteomyelitis in Children
S. aureus - the most common cause
long bones - most commonly
symptoms:
Fever
Bone pain
Inability to bear weight.
May be clinically occult: chronic back pain and low-grade fever
Diagnosis:
White blood cell (WBC) count is elevated
Erythrocyte sedimentation rate (ESR) - elevated.
Blood cultures - positive in 50% of cases.
MRI - The most sensitive radiological test
S. Aureus
- The most common cause of
septic arthritis
May be associated with
joint destruction
.
Symptoms:
Intense
pain
on motion of the affected joint
Swelling
Fever
Endocarditis,
Hemodialysis,
Diabetics
IV drug use
Risk in Adults:
Diabetic ulcers, surgery, trauma.
Draining fistula
Continued drainage
Contiguous Spread
Bone biopsies and culture - THE MOST ACCURATE
S. aureus

- most common cause
Can result in
neurologic compromise
If the neurologic symptoms develop,
Surgical intervention is a medical emergency
.
Aspiration of the joint fluid:
Turbid fluid,
>50,000 PMNs
Gram-positive cocci
in clusters.
Labs:
The most commonly involved joints:
the knees, shoulders, hips, and phalanges
Mri - most sensitive radiologic test
Fever
Cough
Bloody sputum
symptoms:
Best Initial Test:
Chest X- ray
Most accurate test:
Sputum Gram's stain and culture
Pneumatoceles
Patchy infiltrates.
diagnosis:
Predisposing Factors:
Diabetes,
HIV infection
Renal insufficiency
S. aureus
-
leading cause of endocarditis
. (25–35% of cases)
Mortality rate - 20 to 40%
Complications: cardiac
valvular insufficiency
, peripheral
emboli
, metastatic
seeding
, and CNS involvement - embolic strokes
New or changing cardiac murmur
Cutaneous evidence - vasculitic lesions

Hemodynamic changes — beginning with respiratory alkalosis, hypotension and fever
Duke's criteria For endocarditis
Major:
Positive blood cultures
Valvular vegetations on Ultrasound
minor:
Fever >38 C
Predisposing Lesion
IV drug abuse
Embolic phenomena
Immunologic phenomena
Oslers Nodes
Roth spots
DEFINITE Endocarditis:

2 Major Criteria
1 Major Criteria and 3 Minor Criteria
5 Minor Criteria
High fever
Toxic clinical appearance
Pleuritic chest pain
Production of purulent (sometimes bloody) sputum
NO HISTORY OF VALVE DAMAGE
suspect in every patient with:
tricuspid valvular endocarditis - in IV drug users
Previously affected valve
.
Patients tend to be
older
Prognosis is worse
left-sided endocarditis
More acute presentation
Successful Management - removal of the device.
S. aureus device-related infections
diagnostic tests:
best initial test:
Blood culture - 95-99% sensitive
S. epidermidis
The
most abundant on the normal skin

Normal flora
of the oropharynx and vagina.
Novobiocin-resistant
Causes Urinary Tract Infections (UTI)
The Most common cause of prosthetic-device Infections
Since these organisms are present on the skin, they
often contaminate cultures
.
Multiple isolation of the same strain
is suggestive of true bacteremia
approach:
Fever
Leukocytosis
Evidence of local infection (erythema or purulent drainage at the IV catheter site)
Systemic signs of sepsis
S. saprophyticus
Penicillin Allergic Patients:
Erythromycin
Clarithromycin
Azithromycin
Lynezolid
Daptomycin
Ceftaroline
vancomycin resistant:
Lynezolid
Quinupristin/dalfopristin
Daptomycin
REFERENCES:

1. Harrison's Principles of Internal Medicine, 19Th Edition

2. Merck Manual of Clinical Diagnosis, 19Th Edition

3. Master the Boards USMLE Step 2 CK, 3rd Edition

Anterior nares
Sites of colonization:
In early 1980s - an outbreak of Toxic Shock Syndrome occurred among young, healthy women.
EXFOLIATIVE TOXIN - Staphylococcal Scalded-Skin Syndrome (SSSS)
Toxins disrupt the desmosomes
Epidermis
splits at the granular layer
Superficial
desquamation

SSSS most often affects
newborns and children.
Skin
Vagina
Axilla
Perineum
Oropharynx
Right- or left-sided embolic disease;
History suggesting a risk
POSSIBLE Endocarditis:
1major +1 minor
3 minor symptom
Full transcript