Staphylococcus

Classificação

Características Gerais e Epidemiologia

Principais características do Staphylococcus Staphylococcus Staphylococcus is a medically important genera of Gram-positive, aerobic cocci. These bacteria form clusters resembling grapes on culture plates. Staphylococci are ubiquitous for humans, and many strains compose the normal skin flora. Staphylococcus

• Cocos gram-positivos
  • Cresce em clusters
  • Assemelha-se a um cacho de uvas
• Imóvel
• Não formador de esporos
• Aeróbios e anaeróbios facultativos
• Catalase-positivos:
  • Enzima que cliva o peróxido de hidrogénio → água e oxigénio
  • Característica distintiva dos estreptococos (que são catalase-negativos)

Espécies clinicamente relevantes

As espécies clinicamente relevantes podem ser classificadas com base na presença (ou ausência) de coagulase Coagulase Enzymes that cause coagulation in plasma by forming a complex with human prothrombin. Coagulases are produced by certain staphylococcus and yersinia pestis. Staphylococci produce two types of coagulase: staphylocoagulase, a free coagulase that produces true clotting of plasma, and staphylococcal clumping factor, a bound coagulase in the cell wall that induces clumping of cells in the presence of fibrinogen. Staphylococcus:

• Estafilococos coagulase-positivos: S. aureus S. aureus Potentially pathogenic bacteria found in nasal membranes, skin, hair follicles, and perineum of warm-blooded animals. They may cause a wide range of infections and intoxications. Staphylococcus
• Espécies de estafilococos coagulase-negativos ( CoNS CoNS Staphylococcus) (geralmente agrupadas):
  • S. epidermidis S. epidermidis A species of staphylococcus that is a spherical, non-motile, gram-positive, chemoorganotrophic, facultative anaerobe. Mainly found on the skin and mucous membrane of warm-blooded animals, it can be primary pathogen or secondary invader. Staphylococcus
  • S. saprophyticus S. saprophyticus A species of gram-positive bacteria in the family staphylococcaceae. It commonly causes urinary tract infections in humans. Staphylococcus
  • Agentes patogénicos pouco frequentes (a lista não é exaustiva):
    • S. lugdunensis
    • S. hominis
    • S. capitis
    • S. haemolyticus

Características distintas

Epidemiologia

• S. aureus S. aureus Potentially pathogenic bacteria found in nasal membranes, skin, hair follicles, and perineum of warm-blooded animals. They may cause a wide range of infections and intoxications. Staphylococcus:
  • Coloniza aproximadamente 30% da população geral
  • Principais causas de infeções adquiridas na comunidade e nosocomiais
• S. epidermidis S. epidermidis A species of staphylococcus that is a spherical, non-motile, gram-positive, chemoorganotrophic, facultative anaerobe. Mainly found on the skin and mucous membrane of warm-blooded animals, it can be primary pathogen or secondary invader. Staphylococcus:
  • Espécies de Staphylococcus Staphylococcus Staphylococcus is a medically important genera of Gram-positive, aerobic cocci. These bacteria form clusters resembling grapes on culture plates. Staphylococci are ubiquitous for humans, and many strains compose the normal skin flora. Staphylococcus mais MAIS Androgen Insensitivity Syndrome frequentemente identificadas na pele humana
  • Causa comum de bacteriemia nosocomial
• S. saprophyticus S. saprophyticus A species of gram-positive bacteria in the family staphylococcaceae. It commonly causes urinary tract infections in humans. Staphylococcus: causa comum de infeções do trato urinário (ITUs) em mulheres jovens sexualmente ativas

Patogénese

Reservatório

As espécies de Staphylococcus Staphylococcus Staphylococcus is a medically important genera of Gram-positive, aerobic cocci. These bacteria form clusters resembling grapes on culture plates. Staphylococci are ubiquitous for humans, and many strains compose the normal skin flora. Staphylococcus fazem parte da flora humana normal:

• Mucosa nasal
• Trato respiratório
• Pele
• Trato GI
• Trato genitourinário ( S. saprophyticus S. saprophyticus A species of gram-positive bacteria in the family staphylococcaceae. It commonly causes urinary tract infections in humans. Staphylococcus)

Transmissão

Staphylococcus aureus Staphylococcus aureus Potentially pathogenic bacteria found in nasal membranes, skin, hair follicles, and perineum of warm-blooded animals. They may cause a wide range of infections and intoxications. Brain Abscess pode ser transmitido por aerossóis e contacto com:

• Indivíduos infetados
• Fluidos corporais
• Objetos contaminados

Fatores de risco

Os fatores de risco para infeção grave por Staphylococcus Staphylococcus Staphylococcus is a medically important genera of Gram-positive, aerobic cocci. These bacteria form clusters resembling grapes on culture plates. Staphylococci are ubiquitous for humans, and many strains compose the normal skin flora. Staphylococcus incluem:

• Hospitalização
• Tratamento cirúrgico
• Procedimentos de ambulatório (por exemplo, diálise)
• Material implantado ou protésico:
  • Pacemakers/desfibrilhadores
  • Cateteres intravasculares
  • Cateteres uretrais
  • Implantes cirúrgicos
  • Válvulas protésicas
• Indivíduos imunodeprimidos
• Residentes em lares
• Utilizadores de drogas injetáveis

Fatores de virulência

Comuns à maioria dos estafilococos:

• Desoxirribonuclease (DNase): despolimeriza o DNA DNA A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine). DNA Types and Structure, componente das armadilhas extracelulares de neutrófilos → ↓ viscosidade do pús
• Fibrinolisina: lisa as paredes de fibrina usadas para conter a infeção → ajudam na disseminação
• Proteases Proteases Proteins and Peptides: degradam proteínas de células-alvo, como componentes de:
  • Matriz extracelular (MEC)
  • Imunidade inata
• Biofilme:
  • Matriz polissacarídica extracelular que envolve a bactéria após ligar-se ao material estranho
  • Funciona como uma barreira protetora contra os antibióticos e o sistema imune do hospedeiro

Staphylococcus aureus Staphylococcus aureus Potentially pathogenic bacteria found in nasal membranes, skin, hair follicles, and perineum of warm-blooded animals. They may cause a wide range of infections and intoxications. Brain Abscess:

• Hialuronidase:
  • Desdobra o ácido hialurónico
  • Facilita a invasão de agentes patogénicos nos tecidos
• Lipase Lipase An enzyme of the hydrolase class that catalyzes the reaction of triacylglycerol and water to yield diacylglycerol and a fatty acid anion. It is produced by glands on the tongue and by the pancreas and initiates the digestion of dietary fats. Malabsorption and Maldigestion e hidrolase:
  • Degradam lípidos
  • Desempenham um papel na invasão
• Hemolisinas e leucocidinas: provocam a morte das células-alvo, incluindo glóbulos vermelhos e células imunes
• Fator de agregação A:
  • Liga-se ao fibrinogénio e a outras proteínas
  • Causa a aglomeração de bactérias no plasma Plasma The residual portion of blood that is left after removal of blood cells by centrifugation without prior blood coagulation. Transfusion Products
  • Particularmente importante na patogénese da endocardite e infeções endovasculares
• Coagulase Coagulase Enzymes that cause coagulation in plasma by forming a complex with human prothrombin. Coagulases are produced by certain staphylococcus and yersinia pestis. Staphylococci produce two types of coagulase: staphylocoagulase, a free coagulase that produces true clotting of plasma, and staphylococcal clumping factor, a bound coagulase in the cell wall that induces clumping of cells in the presence of fibrinogen. Staphylococcus:
  • Converte o fibrinogénio em fibrina para formar uma parede em redor do local da infeção (pseudocápsula)
  • Promove a formação de abcessos
• Toxinas esfoliativas A e B:
  • Exotoxinas
  • Causam SSSS SSSS Staphylococcal scalded skin syndrome (SSSS), also known as Ritter disease and staphylococcal epidermal necrolysis, is a toxin-mediated condition caused by Staphylococcus aureus. The exfoliative toxin produced disseminates and cleaves desmoglein 1 in the epidermis, causing separation and detachment of the skin. Staphylococcal Scalded Skin Syndrome (SSSS)
    • Clivagem do complexo desmogleína-1 no estrato granuloso
    • Interrompem a adesão queratinócitos-queratinócitos
    • Separação e descolamento da epiderme superficial
• Superantigénios:
  • Englobam as exotoxinas:
    • Toxina da síndrome do choque tóxico tipo 1 ( TSST-1 TSST-1 Toxic Shock Syndrome)
    • Enterotoxina B
  • Causam síndrome do choque tóxico ( TSS TSS Toxic shock syndrome (TSS) is an acute, multi-systemic disease caused by the toxin-producing bacteria, Staphylococcus aureus and Streptococcus pyogenes. Staphylococcal TSS is more common and associated with tampons and nasal packing. Toxic Shock Syndrome):
    • Ligam-se ao MHC classe II das células apresentadoras de antigénio → reticulações com a região β do recetor de células T ( TCR TCR Molecules on the surface of T-lymphocytes that recognize and combine with antigens. The receptors are non-covalently associated with a complex of several polypeptides collectively called CD3 antigens. Recognition of foreign antigen and the major histocompatibility complex is accomplished by a single heterodimeric antigen-receptor structure, composed of either alpha-beta or gamma-delta chains. Adaptive Cell-mediated Immunity)
    • Estimulam a ativação de células T e levam à libertação exagerada de citocinas
    • Resultam numa resposta inflamatória excessiva
• Outras enterotoxinas:
  • Exotoxinas termoestáveis
  • Modo de ação desconhecido
  • Podem causar gastroenterite (intoxicação alimentar)

CoNS CoNS Staphylococcus:

• Adesinas: auxiliam na adesão de CoNS CoNS Staphylococcus às células hospedeiras
• Urease Urease An enzyme that catalyzes the conversion of urea and water to carbon dioxide and ammonia. Nocardia/Nocardiosis:
  • Produzida por S. saprophyticus S. saprophyticus A species of gram-positive bacteria in the family staphylococcaceae. It commonly causes urinary tract infections in humans. Staphylococcus
  • Hidrolisa a ureia → C0₂ e amónia → ↑ pH pH The quantitative measurement of the acidity or basicity of a solution. Acid-Base Balance da urina
  • Torna-o particularmente virulento no trato urinário

Doenças Causadas por S. aureu s

Infeções

A espécie Staphylococcus aureus Staphylococcus aureus Potentially pathogenic bacteria found in nasal membranes, skin, hair follicles, and perineum of warm-blooded animals. They may cause a wide range of infections and intoxications. Brain Abscess pode causar uma ampla gama de infeções, incluindo (mas não limitado a):

• Infeções da pele e dos tecidos moles Moles Primary Skin Lesions
  • Foliculite
  • Impetigo Impetigo Impetigo is a highly contagious superficial bacterial infection typically caused by Staphylococcus aureus (most common) and Streptococcus pyogenes. Impetigo most commonly presents in children aged 2 to 5 years with lesions that evolve from papules to vesicles to pustules, which eventually break down to form characteristic “honey-colored” crusts. Impetigo
  • Celulite
  • Abcesso
  • Fasceíte necrotizante
  • Infeção da ferida cirúrgica
• Infeção da circulação sanguínea → pode propagar a infeção para outros tecidos
• Endocardite infeciosa (EI)
  • Formação de vegetações valvulares cardíacas
  • Pode libertar êmbolos sépticos → complicações embólicas e/ou infeção metastática
  • O S. aureus S. aureus Potentially pathogenic bacteria found in nasal membranes, skin, hair follicles, and perineum of warm-blooded animals. They may cause a wide range of infections and intoxications. Staphylococcus está associado à infeção aguda e rapidamente progressiva.
• Pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia
  • O S. aureus S. aureus Potentially pathogenic bacteria found in nasal membranes, skin, hair follicles, and perineum of warm-blooded animals. They may cause a wide range of infections and intoxications. Staphylococcus causa pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia bacteriana secundária em indivíduos com influenza Influenza Influenza viruses are members of the Orthomyxoviridae family and the causative organisms of influenza, a highly contagious febrile respiratory disease. There are 3 primary influenza viruses (A, B, and C) and various subtypes, which are classified based on their virulent surface antigens, hemagglutinin (HA) and neuraminidase (NA). Influenza typically presents with a fever, myalgia, headache, and symptoms of an upper respiratory infection. Influenza Viruses/Influenza.
  • Complicações:
    • Infeção necrosante → destruição tecidual → cavitação pulmonar
    • Abcesso pulmonar
    • Empiema
• Artrite séptica
• Osteomielite
  • Infeção do osso
  • Pode desenvolver-se por disseminação hematogénica ou não hematogénica
• Infeções de dispositivos médicos, como:
  • Cateteres IV
  • Válvulas protésicas
  • Articulações protésicas
  • Pacemakers

Doenças mediada por toxinas

Doenças Causadas por ECN

Os estafilococos coagulase-negativos podem causar muitas das mesmas condições que S. aureus S. aureus Potentially pathogenic bacteria found in nasal membranes, skin, hair follicles, and perineum of warm-blooded animals. They may cause a wide range of infections and intoxications. Staphylococcus. Dentro das principais infeções estão incluídas:

• Infeções de dispositivos médicos (particularmente S. epidermidis S. epidermidis A species of staphylococcus that is a spherical, non-motile, gram-positive, chemoorganotrophic, facultative anaerobe. Mainly found on the skin and mucous membrane of warm-blooded animals, it can be primary pathogen or secondary invader. Staphylococcus)
  • Cateteres IV
  • Válvulas protésicas
  • Pacemakers
  • Articulações protésicas
  • Derivações do SNC
  • Implantes mamários
• Infeção da ferida cirúrgica
• EI (válvula nativa e protésica)
• Osteomielite
• ITUs (particularmente S. saprophyticus S. saprophyticus A species of gram-positive bacteria in the family staphylococcaceae. It commonly causes urinary tract infections in humans. Staphylococcus )

Antibióticos e Resistência

Suscetibilidade aos antibióticos

As espécies de Staphylococcus Staphylococcus Staphylococcus is a medically important genera of Gram-positive, aerobic cocci. These bacteria form clusters resembling grapes on culture plates. Staphylococci are ubiquitous for humans, and many strains compose the normal skin flora. Staphylococcus podem desenvolver resistência a antibióticos, sendo necessária a identificação da suscetibilidade para o tratamento adequado. As espécies são frequentemente designadas como:

• Sensíveis à meticilina
• Resistentes à meticilina
• Resistentes à vancomicina

Mecanismo de resistência

• Meticilina: resistência mediada pela proteína de ligação à penicilina (PBP)
  • Mutações nas PBPs PBPs Bacterial proteins that share the property of binding irreversibly to penicillins and other antibacterial agents derived from lactams. The penicillin-binding proteins are primarily enzymes involved in cell wall biosynthesis including muramoylpentapeptide carboxypeptidase; peptide synthases; transpeptidases; and hexosyltransferases. Penicillins (codificadas pelo gene Gene A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. Basic Terms of Genetics mecA ) → ↓ afinidade das penicilinas para a PBP
  • Apesar das mutações, estas PBPs PBPs Bacterial proteins that share the property of binding irreversibly to penicillins and other antibacterial agents derived from lactams. The penicillin-binding proteins are primarily enzymes involved in cell wall biosynthesis including muramoylpentapeptide carboxypeptidase; peptide synthases; transpeptidases; and hexosyltransferases. Penicillins ainda são capazes de produzir uma parede celular.
• Vancomicina: alteração na síntese de peptidoglicano
  • Conferido pelo gene Gene A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. Basic Terms of Genetics vanA (no plasmídeo)
  • Adquirido por Enterococcus Enterococcus Enterococcus is a genus of oval-shaped gram-positive cocci that are arranged in pairs or short chains. Distinguishing factors include optochin resistance and the presence of pyrrolidonyl arylamidase (PYR) and Lancefield D antigen. Enterococcus is part of the normal flora of the human GI tract. Enterococcus resistente à vancomicina (VRE)
  • Altera o alvo de peptidoglicano D-alanil-D-alanina para D-alanil-D-lactato ou D-alanil-D-serina → ligação pobre de glicopeptídeos e sem interrupção da síntese da parede celular

Escolhas de antibióticos

O agente de escolha e a duração do tratamento para infecção por Staphylococcus Staphylococcus Staphylococcus is a medically important genera of Gram-positive, aerobic cocci. These bacteria form clusters resembling grapes on culture plates. Staphylococci are ubiquitous for humans, and many strains compose the normal skin flora. Staphylococcus dependem da área do corpo afetada, da gravidade da infecção e da sensibilidade antibiótica da cepa.