Staphylococcus spp. and Micrococcus spp.

• Medically important bacteria/microorganism – microorganisms that are causing infection to human
• Workflow in Bacterial Identification:

  1. Specimen Collection
  2. Direct Microscopic Examination
  3. Culture
  4. Bacterial Identification (Macroscopic & Microscopic)
  5. Biochemical Test
  6. Anti-Susceptibility Testing
• STAPHYLOCOCCUS SPP

  • Family: Staphylococcaceae (ceae : family’s name)
  • Catalase (+)
  • Coagulase (+) and some are Coagulase (-)
• STAPHYLOCOCCUS SPP


  Gram (+) [purple] cocci in singly, in pairs, and in grapelike clusters
• Catalase - Common biochemical test that is associated with staphylococcus
• Coagulase Negative Staphylococcus (CoNS) - staphylococci that are coagulase negative
• what family does Staphylococcaceae resembles?

  micrococcaceae genus Micrococcus spp.
• characteristics of micrococcaceae that resembles staphylococcus spp.

  • Catalase (+)
  • Coagulase (-)
  • Gram (+) cocci in pairs, tetrads, and ultimately, irregular clusters
  • Found in environment and human skin
  • Colonies: yellow pigment
• Other normal flora that resembles staphylococcus:

  Kocuria spp. & Kytococcus spp.
• In terms of characteristics, the following species resembles staphylococci:

  Rothia mucilaginosa & Aerococcus spp. & Alloiococcus otitis
• difference of staphylococcus and micrococcus

  A) (-)

  B) (+)

  C) (+)

  D) Negative (-) [no growth; inhibited by furoxone]

  E) Positive (+) [not inhibited by furoxone]

  F) (+)

  G) (-)

  H) Resistance

  I) Sensitive

  J) Resistance

  K) Sensitive

  L) Sensitive

  M) Resistance

  N) (-) Except: M. kristinae and M. varians [facultative an

  
• Micrococci – Obligate Aerobe – Oxidation; requires oxygen to grow and for metabolism; use glucose with the presence of oxygen
• Staphylococci – Facultative Anaerobe – Fermentation; gumagamit ng organic compounds
• Disk Diffusion method

  • Gagamitan ng MHA or Blood Agar Plate
  • Magc-culture ng organism [first step]
  • Culture entirely; cover the entire media with bacteria - On top of the culture, maglagay ng antibiotic disk [bacitracin, lysosome, lysostaphin] (on top of the lawn [culture]) - Incubate it for about 18-24 hours - Result [hinahanap natin ‘yung zone of inhibition]
  • Measure the zone of inhibition
  • Method Interpretation (+): susceptible/sensitive [more than 10mm] ▪ Interpretation (-): resistant/resistance
• Not all staphylococcus are Microdase negative. The following bacteria are staphylococcus that are microdase positive:

  S. sciuri o Macrococcus caseolyticus o S. lentus o S. vitulus
• Staphle meaning “bunches of grapes”
• staphylococcus nonmotile, non–spore-forming, and aerobic or facultatively anaerobic except for S. saccharolyticus and S. aureus subsp. Anaerobius (obligate anaerobe and they may be catalase negative (-))
• Normal flora of skin and mucous membranes of humans and animals - staphylococcus & Micrococcus
• staphylococci - Colonies: medium-sized (4-to-8-millimeter [mm]) and appear cream-colored, white, or rarely light gold, and “buttery looking” [butyrous]
• staphylococci - Naga-appear daw ang golen yellow kapag older ang culture [more than 24 hours]
• Slime layer: glycocalyx - Staphylococcus aureus and Staphylococcus epidermidis

  • Polysaccharide; appearing as a slime layer & Kapag nagdikit dikit, nagfform ng biofilm
  • Biofilm [capable of adhering to inorganic surface and may be resistant or may overcome actions of antibiotic]
• Fastidious strains requirements:

  CO2, hemin [x-factor], or menadione with at least 48 hours of incubation
• S. aureus

  NORMAL FLORA

  1. Anterior nares
  2. Nasopharynx
  3. Perineal area
  4. Skin
  5. Colonizer of mucosa

  INFECTIONS

  • cutaneous infection (folliculitis, furuncles, carbuncles, and bullous impetigo)
  • food poisoning
  • Scalded skin syndrome (SSS)
  • Toxic shock syndrome (TSS)
  • Toxic epidermal necrolysis (TEN)
• S. epidermis

  NORMAL FLORA: Skin & Mucous membranes

  INFECTIONS: nosocomial infections
• S. haemolyticus

  NORMAL FLORA: Skin & Mucous membranes

  INFECTIONS:

  1. Wound
  2. Septicemia (bacterial in blood)
  3. UTIs
  4. native valve infections
• S. lugdunensis

  NORMAL FLORA: Skin & Mucous membranes

  INFECTIONS: catheter-related bacteremia and endocarditis
• S. saprophyticus

  NORMAL FLORA: Skin & Mucous membranes & Genitourinary tract

  INFECTIONS: UTI (in adolescent girls and young women)
• Micrococcus spp


  NORMAL FLORA: Skin

  INFECTIONS: Rarely implicated in infections
• Kocuria spp.


  NORMAL FLORA: Mucosa

  INFECTIONS: Rarely implicated in infections
• Kytococccus spp


  NORMAL FLORA: Oropharynx

  INFECTIONS: Rarely implicated in infections
• Cutaneous infection [skin and wound infection]

  o Folliculitis – inflammation or infection in the hair follicle [no systemic manifestation]

  o Furuncles – boil; formation of pus [no systemic manifestation]

  o Carbuncles – even larger; more invasive type of infection than the furuncle; can progress into deeper layer; systemic manifestation [fever, chills]

  o Bullous impetigo – these are like chicken pox lesions, but larger; erythema [redness]: pustule
• STAPHYLOCOCCUS AUREUS VIRULENCE FACTORS

  1. Enterotoxins
  2. Toxic Shock Syndrome Toxin-1
  3. Exfoliative Toxin
  4. Cytolytic Toxin or Cytotoxin
  5. Enzymes
  6. Protein A
  7. Peptidoglycan
  8. Teichoic Acid
• Enterotoxins

  • Groups A-E and G-J - Serologically identified
  • Infections associated with Enterotoxins:
  • Staphylococcal food poisoning [A-E] (tinitignan ‘yung on-set of manifestation; 2-6 hours after consuming the contaminated food
  • Toxic Shock Syndrome [B, C, G, I]
  • Staphylococcal pseudomembranous enterocolitis [B] [contaminated milk product]
  • Heat stable exotoxins (100°C for 30 minutes)
• Toxic Shock Syndrome Toxin-1

  • Toxic Shock Syndrome [TSS]
  • Previously known as enterotoxin F
  • Also known as pyrogenic exotoxin C - has systemic effect [fever, hypotension [decreased plasma volume; can lead to shock and death; more affected: women using tampons during menstruation], desquamation]
• Exfoliative Toxin

  • Epidermolytic toxin A & B
  • Staphylococcal SSS - Also known as Ritter disease
  • [Serine proteases splits the intracellular bridges of the epidermis, resulting to burn-like effect or extensive sloughing of epidermis producing “burn-like” effect]
• Cytolytic Toxin or Cytotoxin - Extracellular proteins that affect red blood cells and leukocytes

  • Lysins [hemolysin; RBC] and Leukocidins [WBC]
  • S. aureus: a, B, y, o hemolysin
• S. aureus, S. epidermidis, and S. haemolyticus have delta hemolysin.
• a-hemolysin: disrupts the smooth muscle in blood vessels and is toxic to erythrocytes, leukocytes, hepatocytes, and platelets
• B-hemolysin: also known as SPHINGOMYELINASE C or “HOT-COLD LYSIN”

  • acts on sphingomyelin in the plasma membrane of RBCs
  • act in CAMP test [Christie, Atkinson, Munch,Peterson] [identification of Streptococcus agalactiae]
  • Enhances hemolytic activity when exposed to hot [37 degree Celsius] and cold [4 degree Celsius] temperature (mas nakakasira ng RBC)
• ō-hemolysin: less toxic than ahemolysin or Bhemolysin