Staphylococcus aureus

Juanita Escobar Martínez

Rodrigo Herrera Caro

III Semestre

PATRÓN DE RESISTENCIA ANTIBIÓTICA -

STAPHYLOCOCCUS AUREUS

INTRODUCTION

Staphylococcus:

• Bacteria Gram-positive cocci formed in grape-like clusters.

• Facultative anaerobes.

• Resistant to hostile conditions.

• Rapid development.

• Ferments carbohydrates and produce pigments (white • to yellow).

• Catalase positive.

• At least 40 species S. epidermidis, S. saprophyticus, S. aureus.

• Commensal nostrils, skin and mucous membranes.

INTRODUCTION

S. aureus:

• "Golden staph" or Oro staphira.

• Stationary and non-spore.

• Capsule slime or mucoid (polysaccharid).

• Coagulase positive.

• Pathogen polymorphic mucocutaneous infections, shock toxic syndromes, toxic food-borne infections, nosocomial infections.

INTRODUCTIONProduct Effect

Capsule Inhibits phagocytosis

Coagulase May prevent the progression of leukocytes in the infected area produce

clots in neighboring capillaries

Exfoliatin Separates the layers of the epidermis, causing Scalded skin Syndrome

Hyaluronidase Decomposes hyaluronic acid of tissues and promotes spread of

infection

Leukocidin Destroys leukocytes producing holes in the cytoplasmic membrane

Lipase Descomposes fats hydrolyzing the bond between glycerol and fatty acids

Proteases Degrades collagen and other tissue proteins

INTRODUCTIONProduct Effect

A Protein Binds to the Fc portion of the antibody inhibiting phagocytosis

Septic shock Syndrome Toxin

Causes rash, diarrhea and shock

Clumping factor Binds bacteria to fibrin, fibrinogen and plastic elements

Fibronectin binding protein

Binds bacteria to the acellular tissue substance, epithelium, endothelium, blood

clots, plastic elements to stay.

α, β, γ and δ toxins Dermonecrotic effect

Leukocidin Destroys neutrophils or cause release of their enzymes

Enterotoxins Superantigens. Cause food poisoning if they are ingested

TSST-1 Superantigen. If they are systemic causes toxic shock

INTRODUCTION

MRSA resistance:•Methicillin-resistant Staphylococcus aureus.

•SCCmec mecA, psm-mec, ccrA and ccrB genes.

•Strains, ACME, mecA.

•mecA encodes PBP2a.

•HA-MRSA and CA-MRSA.

•Any strain of S. aureus that has developed resistance to beta-lactam antibiotics (penicillins and cephalosporins).

OBJECTIVE

“To detect antibiotic resistance pattern,

MRSA, SCCmec types and accessory gene

regulator (agr)

groups among isolates of S. aureus.”

MÉTODOSAislamiento de bacterias :

• Funda

Prueba Fundamento Objetivo Imagen

Catalasa Descomposición del peróxido de hidrógeno

Distinguir de especies de Streptococcus, Enterococcus y Lactococcus.

Coagulasa Reacciona con protrombina fibrinógeno

se convierte en fibrina

Diferenciar de Staphylococcus

coagulasa- negativa

MSA Alta concentración de NaCl, manitol y rojo de

fenol (pH)

Identificar Staphylococcus

coagulasa-positivos

Test Dnasa Agar

Detección de enzimas desoxirribonucleasas.

Diferenciación entre especies de

Staphylococcus

MÉTODOS

Prueba de susceptibilidad antibiótica

• AST Método de Kirby Bauer.

• Fundamento determina la sensibilidad de un agente microbiano frente a un antibiótico o quimioterápico.

• Antibiograma o prueba de susceptibilidad bacteriana frente a drogas específicas.

• Objetivo determinar a cuál de los antibióticos es resistente la bacteria.

• Sensible (S), Intermedio o Moderadamente sensible (I) y Resistente (R).

MÉTODOS

Extracción de DNA genómico

1. Lisis de bacterias Gram-positivas lisostafina.2. Degradación del RNA opcional.3. Precipitación de proteínas ácido acético.4. Precipitación de DNA isopropanol.5. Almacenamiento en TE buffer ácido etilendiaminotetraacético (EDTA).6. Marcación con FISH hibridación fluorescente in situ.

MÉTODOSPCR

• Obtención de muchas copias de una fragmento de DNA particular amplificación de un fragmento de DNA.

• Fundamento propiedad natural de los ADN polimerasas para replicar hebras de ADN ciclos de altas y bajas temperaturas alternadas separar hebras de ADN recién formadas dejar que las hebras de ADN vuelvan a unirse para poder duplicarlas nuevamente.

• Sensibilidad, Especificidad, Eficiencia, Fidelidad.

• Desnaturalización, alineamiento, extensión, elongación final, conservación.

SCCmec III

325 pb

280pb94,2%

SCCmec V

5,8%

RESULTADOS

RESULTADOS

Tetraciclina Eritromicina

ClindamicinaTrimetoprim

Gentamicina

Ciprofloxacina

Amoxicilina

RESULTADOS

Author Conclusion Yes or not

Shittu All of the isolates were susceptible to vancomycin and linezolid.

YES

Sharma All clinical isolates were susceptible to vancomycin YES

Japoni 74.3% of isolates in south of Iran were SCCmec type III

YES

Ho 91.6% of clinical isolates belonged to arg group I YES

DISCUSSION

• Staphylococcus aureus has particular ways of manifestations and resistances that could complicate a infection´s treatment.

• Strain type is determinant in the expression of resistant genes that are a challenge when a treatment will be developed.

CONCLUSIONS

• Although there are two antibiotics which can treat the infection by S. aureus could cause a resistance because of chronic use.

• The knowledge of the kind of Strain that cause the infection is important to guide a treatment plan, avoiding the use of ineffective antibiotics.

CONCLUSIONS

• COSSART, Pascale; BOQUET, Patrice; NORMARK, Staffan; RAPPUOLI, Rino. Cellular Microbiology. 2nd edition. ASM Press. Washington, DC. 2005. Pags 22-

23.

• NESTER, Eugene; ANDERSON, Denise; ROBERTS, C. Evans Jr; NESTER, Martha. Microbiología humana. 5ta edición (traducción). Manual Moderno. México. 2007. Pags 317-318, 562-563, 582-585, 613-614, 912-913.

BIBLIOGRAFÍA