Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive...
-
Upload
ashley-cook -
Category
Documents
-
view
218 -
download
2
Transcript of Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive...
![Page 1: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/1.jpg)
Staphylococcus
Dr Julian Ng
![Page 2: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/2.jpg)
General• About 40 known Staphylococcus spp.• Gram Stain: Gram positive coccus; 0.5µm-
1.5µm• usu. arranged in grape-like clusters but may
also be seen as pairs/tetrads or short chain
![Page 3: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/3.jpg)
• All except S. saccharolyticus and S. aureus subsp. anaerobius are facultative anaerobes
• Grows readily in most culture media and can grow in the presence of 10% NaCl
• Generally, they are catalase positive (rare exceptions)
![Page 4: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/4.jpg)
Clinical Significance
• Most are opportunists• Can colonize skin and mucous membranes• Breaks in the epithelial barrier may allow
them to becomes pathogenic
![Page 5: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/5.jpg)
S. aureus
• Clinically most important species• Can cause a wide variety of human diseases• Possess many virulence factors• Up to 35% of humans are persistent nasal
carriers• Easily transferrable from human to human via
skin contact– Importance in infection control esp. in Methicillin-
resistant Staphylococcus aureus (MRSA)
![Page 6: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/6.jpg)
• Most common cause of nosocomial pneumonia and skin and soft tissue infections
• 2nd most common staphylococcal spp. to cause primary bacteraemia in hospitals
• Typical colony: Pigmented (cream yellow to orange), haemolytic on blood agars
![Page 7: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/7.jpg)
• Biochemical characteristics: Catalase positive, Coagulase positive, slide agglutination (clumping factor) positive
![Page 8: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/8.jpg)
Key Test
![Page 9: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/9.jpg)
Clinical spectrum
• Any localised infection may become invasive and can lead to bacteraemia
• Systemic infections such as primary or secondary bacteraemia, endocarditis, meningitis can occur
• Toxin-mediated diseases includes staphylococcal toxic shock syndrome, staphylococcal food poisoning, staphylococcal scaled skin syndrome
![Page 10: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/10.jpg)
Localised infections• Very common cause of infection by
staphylooccal spp.• Often results in pus formation• Can result in skin, soft tissue infection or deep
abscesses
Impetigo
![Page 11: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/11.jpg)
Boil (Furuncle)
![Page 12: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/12.jpg)
Carbuncle
![Page 13: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/13.jpg)
Stye
![Page 14: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/14.jpg)
Surgical wound infections: many causes including S. aureus
![Page 15: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/15.jpg)
Oral infections
• Acute parotitis• Angular cheilitis• Mucositis• Etc
![Page 16: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/16.jpg)
Acute parotitis: various causes
Including bacteria …
Alpha-haemolytic strepsS. aureus
Haemophilus sppAnaerobes
And many more
![Page 17: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/17.jpg)
Angular cheilitis: multifactorial including …
Candida spp, S. aureus, beta haemolytic streps
![Page 18: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/18.jpg)
Staphylococcal mucositis
![Page 19: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/19.jpg)
Local staphlococcal infectionsinside oral cavity
![Page 20: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/20.jpg)
Toxin-mediated
• Toxic shock syndrome toxin (TSST-1) is a super-antigen capable of activating large number of T cells
• Was associated with use of tampons but is also known to be associated with postoperative wound or soft tissue infections
![Page 21: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/21.jpg)
![Page 22: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/22.jpg)
• Preformed, heat-resistant enterotoxin mediates staphylococcal food poisoning (symptoms in 2-6 hours; usu self-limiting)
• Exfoliative toxins A and B results in staphylococcal scalded skin syndrome; usu in infants and neonates
![Page 23: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/23.jpg)
• Panton-Valentine Leukocidin (PVL) consists of 2 components S and F, together with γ exotoxin lyses WBC resulting in massive release of inflammatory mediators responsible for necrosis and severe inflamation
• PVL is an important virulence factor in MRSA infections
![Page 24: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/24.jpg)
MRSA
• Methicillin-resistant S. aureus• Resistant to all penicillins, cephalosporins, and
penems• Usually multiply-resistant• Vancomycin resistance is very rare – so far• Hospital-acquired• Community-acquired cases now (CA MRSA)
![Page 25: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/25.jpg)
Coagulase-negative staphylococcal spp (CoNS)
• S. epidermidis – most frequently isolated staphylococcal spp.
• Colonises moist body areas such as auxillae, inguinal and perianal areas, anterior nares and toe webs
• Important cause of nosocomial infection esp. S. epidermidis
• Usu causes nosocomial infections in patients with predisposing factors such as immunodeficiency/ immunocompromised or presence of foreign bodies
![Page 26: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/26.jpg)
• Ability to form biofilm is most important factor in foreign body infections by CoNS– Important to remove/ replace foreign body in
treatment
![Page 27: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/27.jpg)
• S. saprophyticus frequently isolated in rectum and genitourinary tract of young women
• Can be causative agent in UTI in young healthy women
• 2nd most common urinary pathogen (other than E. coli) in uncomplicated cystitis in young women
• Colony counts of ≥ 105 CFU/ml usu. indicative of significant bacteriuria
![Page 28: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/28.jpg)
Line-related sepsis
• Frequently staphylococcal
• CNS common
• S. aureus particularly serious
![Page 29: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/29.jpg)
Line-related sepsis with S. aureus = get help from Infectious Disease
physician
![Page 30: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/30.jpg)
Antimicrobial susceptibility• MRSA can be due to 3 different resistance mechanisms
– Production of penicillin-binding protein 2a (PBP2a) encoded by mecA gene
– Production of beta-lactamase– Production of modified intrinsic PBPs
• Resistance due to mecA can be detected via cefoxitin disk diffusion or dilution methods according to CLSI breakpoints (≤ 21mm – resistant, ≥ 8µg/ml – resistant, respectively)
• Resistance due to beta-lactamase production can be detected via the use of beta-lactamase inhibitor such as clavulanic acid which would result in an increase in zone size (disk diffusion method) or decrease of 2 dilutions
![Page 31: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/31.jpg)
• Vancomycin-intermediate S. aureus (VISA) is thought to be due to changes in cell wall
• S. aureus with vancomycin minimum inhibitory concentration (MIC) of 4-8µg/ml are VISA according to CLSI guidelines
• VRSA due to acquisition of vanA gene was first reported in 2002 in US
• Vancomycin MIC ≥ 16µg/ml = VRSA
VRSA uncommon
![Page 32: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/32.jpg)
Treatment
• Drain pus, remove foreign material and dead tissue
• Methicillin – cloxacillin• (Erythromycin, clindamycin)• Vancomycin• Topical agents: e.g. mupirocin
![Page 33: Staphylococcus Dr Julian Ng. General About 40 known Staphylococcus spp. Gram Stain: Gram positive coccus; 0.5µm- 1.5µm usu. arranged in grape-like clusters.](https://reader035.fdocuments.in/reader035/viewer/2022062422/56649ef35503460f94c0593d/html5/thumbnails/33.jpg)
References
• Manual of Clinical Microbiology 10th Ed. Chap 19 pp 308-330
• Jawetz, Melnick, Adelberg’s Medical Microbilogy 25th Ed. Chap 13 pp 185-190