Gram-Positive Cocci Infections & Fever PDF

Gram-positive Cocci Infections & Fever Robert M. Taylor, PhD, FCCM (He/Him) Division Head (Interim), Microbiology - NL Health Services Clinical Microbiologist, Public Health Microbiology Laboratory Assistant Professor, Laboratory Medicine, Memorial University Jan 9t...

Gram-positive Cocci Infections & Fever Robert M. Taylor, PhD, FCCM (He/Him) Division Head (Interim), Microbiology - NL Health Services Clinical Microbiologist, Public Health Microbiology Laboratory Assistant Professor, Laboratory Medicine, Memorial University Jan 9th 2025 1 Disclosures No disclosures… 2 Treaty Land Acknowledgment We acknowledge that the lands on which Memorial University’s campuses are situated are in the traditional territories of diverse Indigenous groups. We also acknowledge with respect the histories and cultures of the Beothuk [bee- oth-uck], Mi’kmaq [mee-gum-maq], Innu [in- new] and Inuit [in-new-eet] of this province. Demasduit (1796 – 1820), one of the last Beothuk woman from NL 3 Case A 52-year-old female with a history of diabetes mellitus and recent left knee arthroscopy presents to the emergency department with severe left knee pain, swelling, and redness for 3 days. She reports fever, chills, and difficulty bearing weight on the affected leg. She denies any recent trauma or travel history. Vitals Temperature: 38.9°C, Heart Rate: 105 bpm, Blood Pressure: 125/80 mmHg, Respiratory Rate: 18/min. Knee: Marked swelling, erythema, warmth, and tenderness over the left knee. Painful and restricted range of motion. Other Systems: No rash, no signs of endocarditis, lungs and heart normal. 4 Case Laboratory Findings WBC: 15,000/µL (neutrophilic predominance) ESR: Elevated CRP: Elevated Blood cultures: Pending Joint aspiration: Turbid yellow fluid, leukocyte count 85,000/µL (90% neutrophils). Gram stain: Polymorphonuclear cells and Gram-positive cocci What’s on your differential for bacterial cause of septic arthritis? 5 Case What’s on your differential for bacterial cause of septic arthritis? Staphylococcus aureus Staphylococcus lugdunensis Group A Streptococcus Group B Streptococcus Streptococcus anginosus Enterococcus faecalis/faecium Broad empiric therapy could be ceftriaxone and vancomycin 6  = important to remember Objectives Recognize components that differentiate a pathogen versus a contaminant Define the role of the total testing process in bacteriology (pre-analytics, analytics and post-analytics) Describe the process and features of a Gram stain Distinguish key characteristics among varying species of: Staphylococci = question for fun Streptococci Enterococci Predict organism identity based on select diagnostic findings, for Staphylococcus aureus, S. lugdunensis, S. saprophyticus, Streptococcus pneumoniae, Group A Streptococci (S. pyogenes), Group B Streptococci (S. agalactiae), and Enterococcus spp. Discover and learn about other important characteristics for each organism regarding; epidemiology, pathogenesis, disease manifestations, diagnostic techniques, first line treatment and public health response 7 Humans are DIRTY! When is it a pathogen?  Depends on SITE Ex. Skin wound..contam? V.S. CSF…likely real 8 What is infection? Infection  Invasion and growth of germs in the body However, it’s not that simple. You need to take many factors into play: Epidemiology of pathogen Patient Risk Factors Pre-analytics Analytics Post-analytics 9 What is infection? Infection  Invasion and growth of germs in the body However, it’s not that simple. You need to take many factors into play: Epidemiology of pathogen How was patient exposed? Patient Risk Factors What is the pathogen? Where does patient live/present? Pre-analytics What is the patients' demographics? Analytics Post-analytics 10 What is infection? Infection  Invasion and growth of germs in the body However, it’s not that simple. You need to take many factors into play: Epidemiology of pathogen Is patient immunocompromised (IC-)? Patient Risk Factors Any co-morbidities? What is patient’s age? Gender? Pre-analytics Social history, sexual history, living arrangements? Analytics Vaccination history? Post-analytics 11 What is infection? Infection  Invasion and growth of germs in the body However, it’s not that simple. You need to take many factors into play: Epidemiology of pathogen How was specimen collected? Patient Risk Factors Was the appropriate container used? Appropriate volume? Sterile technique? Pre-analytics Was the specimen labelled properly? Was it transported quickly? If not, was proper Analytics storage media used? Post-analytics 12 What is infection? Infection  Invasion and growth of germs in the body However, it’s not that simple. You need to take many factors into play: Epidemiology of pathogen What was done with the specimen? Patient Risk Factors Agar plates used? Gram stain? PCR? Serology? What growth is seen? How much is there? Pre-analytics Any contamination? What is the identification (ID)? Analytics What is the susceptibility report (AST)? Does it make sense? Should any be confirmed? Post-analytics 13 What is infection? Infection  Invasion and growth of germs in the body However, it’s not that simple. You need to take many factors into play: Epidemiology of pathogen How was the culture reported? Patient Risk Factors Was public health informed if notifiable disease? Pre-analytics Is the report clear to inform clinicians? How will report affect patient management? Analytics Public health interventions as needed Post-analytics 14 What is infection? Infection  Invasion and growth of germs in the body However, it’s not that simple. You need to take many factors into play: Epidemiology of pathogen Total Testing Process: Patient Risk Factors o Pre-analytics have highest rate of errors o Analytics/Post-analytics are Lab controlled Pre-analytics Analytics Post-analytics 15 Pre-Analytics Specimen Collection Crucial procedure to the microbiology lab More is always better! Ex. Blood cultures 2 sets (Aerobic + Anaerobic), >1 sites Largest factor in accurate results = volume! volume More Better is 16 Analytics (Bacteriology) Depends on specimen type! Gram stain? Helps guide work up and Tx Media? Enriched – extra growth factors Selective – antibiotics added to suppress Differential – indicators added to see Chrom agar for Urines Chrom agar for MRSA 17 Analytics (Bacteriology) S. pneumoniae S. aureus E. faecalis Depends on specimen type! Morphology? Hemolysis patterns? α – Greening (ex. Streptococcus pneumoniae) β – Clearing (ex. Staphylococcus aureus) γ – None (ex. Enterococcus faecalis) Colour? Ex. S. aureus (gold) Ex. E. coli (grey) Ex. Chryseobacterium (orange) Shape? Ex. Pseudomonas aeruginosa (metallic) Ex. Klebsiella (mucoid) Ex. Streptococcus anginosus (tiny, 90% of all S. aureus are R to Penicillin (penicillinases) MRSA – Methicillin Resistant S. aureus 1st line therapy MSSA is intrinsically susceptible; MRSA intrinsically resistant to: Local measures (debridement, catheters, etc.) β-lactam combination agents (amox-clav, pip-tazo) Antibiotics selected based on Oral cephems (cephalexin, cefuroxime) Most cephalosporins I-IV (cefazolin, ceftriaxone, cefotaxime) Infections site Carbapenems (meropenem, ertapenem, imipenem) Severity Probability of resistance tatttite canada MRSA? in Ceftaroline/Ceftobiprole (bind to PBP-2a directly) TMP-SMX, Clindamycin, Doxycycline, Vancomycin, Linezolid, Daptomycin 37 Question 4) What protein does ceftrobiprole bind to in MRSA? a) PBP-1a b) PBP-2a c) PBP-3a d) PBP-4a 38 Question 4) What protein does ceftrobiprole bind to in MRSA? a) PBP-1a b) PBP-2a c) PBP-3a d) PBP-4a 39  s aureus virulent like less Treat ignore completely S. lugdunensis can't Epidemiology Worldwide | Transmission - Direct Normal flora?  Yes, skin lessin rose Most similar CNST to S. aureus  Think endocarditis (mainly native valve), bacteremia, joint infections S Canstill cause other aureus symptoms 40 S. lugdunensis Diagnosis Same methods as S. aureus Biochemicals slightly different Catalase POS Coagulase (slide) POS Coagulase (tube) NEG 1st line therapy Warranted to treat when in sterile site, similar to S. aureus >90% Pen R Treat similar to MSSA (Oxacillin, Cefazolin, etc.) 41 Question 5) A 45-year-old patient presents to the emergency department with a painful skin abscess on the forearm. Upon examination, the abscess is warm, erythematous, and fluctuant. A sample is obtained for culture, and laboratory results reveal the presence of Staphylococcus lugdunensis. What clinical feature is often associated with S. lugdunensis infections? lugderensis causes by a) Superficial skin infections commonly b) Rapid onset of pneumonia more c) Native valve endocarditis d) Asymptomatic urinary tract colonization 42 Question 5) A 45-year-old patient presents to the emergency department with a painful skin abscess on the forearm. Upon examination, the abscess is warm, erythematous, and fluctuant. A sample is obtained for culture, and laboratory results reveal the presence of Staphylococcus lugdunensis. What clinical feature is often associated with S. lugdunensis infections? a) Superficial skin infections b) Rapid onset of pneumonia c) Native valve endocarditis d) Asymptomatic urinary tract colonization 43 Other Coagulase Negative Staphylococci (CNST) (S. epidermidis, S. hominis, S. haemolyticus, etc.) Clinical Disease Have to weigh decisions of Contam v.s. pathogen! When seen ¼ bottles in blood culture = Contam! Common manifestations: S. epidermidis – Prosthetic valve endocarditis, surgical wounds S. haemolyticus – medical device implantation infection 44 S. saprophyticus Epidemiology Worldwide. Normal flora? Yes, skin Pathogenesis Opportunistic, colonize skin Virulence  Biofilms, exotoxins, enzymes, drug resistance AND Protein hemagglutinin/fimbrae (to bind uroepithelial cells) Urease (to invade bladder wall) Clinical Disease CA-UTIs, commonly 16-35 F, late summer season Usually community acquired 45 S. saprophyticus Diagnosis Same methods as S. aureus Biochemicals: Catalase POS Coagulase (slide/tube) NEG Urease POS Seen in urine pos for saprophyticus 1stline therapy negfor allotherstaph >90% Pen R AST is NOT usually done – low resistance trends Treat like classic UTI – Nitrofurantoin, TMP-SMX, Cephalexin 46 Question 6) A 65-year-old patient undergoes knee joint replacement surgery, and postoperatively, a superficial wound culture of the knee reveals the presence of Staphylococcus hominis. What is the most likely explanation for the isolation of S. hominis in this case? a) True infection b) Contamination during sample collection c) Surgical site infection d) Hematogenous spread from another infection site 47 Question 6) A 65-year-old patient undergoes knee joint replacement surgery, and postoperatively, a superficial wound culture of the knee reveals the presence of Staphylococcus hominis. What is the most likely explanation for the isolation of S. hominis in this case? a) True infection b) Contamination during sample collection c) Surgical site infection d) Hematogenous spread from another infection site 48 Question 7) Lab calls you to report a Gram stain on a blood culture, 2/2 sets are positive and show this morphology. Whis pathogens are you concerned about? Would you initiate treatment, and if yes, which agent(s)? 49 Question 7) Lab calls you to report a Gram stain on a blood culture, 2/2 sets are positive and show this morphology. Whis pathogens are you concerned about?  S. aureus, S. lugdunensis…potentially other CNST Would you initiate treatment, and if yes, which agent(s)?  Yes. Bacteremia with potential S. aureus. Vancomycin commonly used in case of MRSA, narrowing therapy after confirmation 50 Streptococci Lancefield “Grouping” (Antigen test to type Streptococcus species) Beta-Hemolytic: A – S. pyogenes Streptococcus pyogenes (GAS)* B – S. agalactiae C – S. dysgalactiae/anginosus S. agalactiae (GBS)* D – S. anginosus group G – S. dysgalactiae/canis/anginosus Viridans Group Strep: Alph hemolytic S. mitis group (resp tract) Causes pneumonia S. pneumoniae* S. anginosus group* S. salivarius group (skin) S. bovis group (GI tract, linked to colorectal cancer) S. mutans group (oral cavity) 51  GAS Epidemiology Worldwide. Normal flora?  Yes, skin/throat Mostin really young or really old Pathogenesis Opportunistic, colonize skin Virulence: M-protein (adherence and evasion) reportable Inhibits opsonization sease to Capsule (prevents phagocytosis) type Toxins! impure others Exotoxins, superantigens 0 Streptolysin O & S 52  GAS Clinical Disease – Part 1 Acute pharyngitis ‘Strep Throat’ 15-30% in children Abrupt sore throat, fever, H/A Self-limited Scarlet Fever IF strep throat was untreated and its a strain that produces exotoxins Red rash on body, red “strawberry tongue” Acute Rheumatic Fever Ag-Ab complexes in tissues causing inflammation, immune system attacks itself Occurs in 0.3-3% of untreated GAS infections Streptococcal Toxic Shock Syndrome Risks are diabetes, IC- (HIV, PWID, alcoholism) “Strawberry tongue” Main Streptococcus strains carry virulence factor – M1 and M3 53  GAS Clinical Disease – Part 2 Impetigo Skin concerns (Pyoderma, Impetigo) Purulent lesions Cellulitis Spreading rash, from surgical infections mainly Necrotizing fasciitis MOST of these are polymicrobial! Extensive and rapid necrotic spread, gangrene of skin, 20-70% mortality Others – Septicemia, Meningitis, Pneumonia, etc. 54 GAS Diagnosis chaining Iftering Gram stain - Coccoid, pairs/chains Media - Blood agar (NEED blood to grow) Morphology – White, β-hemolytic Biochemicals Catalase NEG PYR POS Antigen testing (low sensitivity) PCR, serology (for Rheumatic fever, streptolysin O) 1st line therapy iGAS is reportable and usually ‘typed’ for M proteins AST is NOT usually done – low resistance trends Treat with  Penicillin (macrolide if allergic) 55 GBS Epidemiology Worldwide | Transmission – Direct/Droplet, Congenital! Normal flora?  Yes, GI and urogenital tract Pathogenesis Opportunistic Virulence: Capsule Hemolysins Fibronectin binding proteins Other selective enzymes 56  GBS Clinical Disease Most Severe form – Neonatal disease Early Onset 3 months Rare, when low birth weight Risk – Colonize maternal urogenital tract (30%) 50% chance to transfer to newborns Prevention – Chemoprophylaxis near birth Given penicillin to during childbirth 57 ensure GBS is cleared and not passed to neonate causingmeningitis GBS Clinical Disease Adults: Bacteremia Female genital tract Postpartum endometritis Pneumonia, sepsis Pneumonia Meningitis – very rare in adults Endocarditis Osteomyelitis Soft skin tissue infections 58 GBS Diagnosis Gram stain - Coccoid, pairs/chains Media - Blood agar (NEED blood to grow) Morphology – White, β-hemolytic Biochemicals Catalase NEG PYR NEG Pregnant screening – Rectal swab 36-38 weeks (carrot broth) PCR 1st line therapy Neonatal GBS is reportable AST is NOT usually done – low resistance trends Treat with  Penicillin (macrolide if allergic) 59 Question 8) A newborn infant (5 days old) presents with lethargy, poor feeding, and irritability. Lumbar puncture reveals elevated white blood cell count and culture confirms the presence of Group B Streptococcus (GBS). What is the most likely source of GBS infection in this case? a) Maternal breast milk b) Intrauterine infection c) Early-onset neonatal sepsis d) Postnatal environmental exposure 60 Question 8) A newborn infant (5 days old) presents with lethargy, poor feeding, and irritability. Lumbar puncture reveals elevated white blood cell count and culture confirms the presence of Group B Streptococcus (GBS). What is the most likely source of GBS infection in this case? a) Maternal breast milk b) Intrauterine infection c) Early-onset neonatal sepsis d) Postnatal environmental exposure 61 S. pneumoniae Epidemiology Worldwide | Transmission – Droplet Normal flora?  Yes, throat resp tract years Pathogenesis Opportunistic Virulence: Capsule (target for vaccines, ~90 serotypes) Pneumolysin (cytotoxin, causes α-hemolysis) C protein (activates cytokines) Autolysin (cell lysis, can see on agar) Other enzymes 62  S. pneumoniae Clinical Disease Meningitis - #1 cause patients >3 months Fever, H/A, neck stiffness, high mortality Bacteremia Otitis media Common peds 6 m. to 3 years Infection of middle ear Sinusitis Mostly viral, but S. aureus/S. pneu #1 bacteria cause Acute H/A, fever, purulent drainage Lower respiratory tract infection Community acquired pneumoniae - #1 cause! CAP acute fever, SOB Lobar pneumonia, Empyema - #1 cause Accumulation of fluid in pleural space Endocarditis Rare 63 S. pneumoniae Diagnosis Gram stain - Coccoid, pairs/chains, ‘lancet’ Media - Blood agar (NEED blood to grow) Morphology – Grey, α-hemolytic Biochemicals Catalase NEG Optochin susceptible Bile solubility POS Antigen, PCR, serology Used to specifySpneumoniae Autolysin effect 1st line therapy Reportable disease confident to identify Use Oxacillin as screening for Pen susceptibility DIFFERENT breakpoints of MICs for dosing Treat with  Penicillin, ceftriaxone, doxycycline, etc. Vaccines 23-valent – Elderly 13-valent – Children, more immunogenic 64 S. anginosus group Epidemiology Commensal flora (GI, oral, genital tracts) Pathogenesis Opportunistic Less virulent than S. pneumoniae Capsule and other enzymes Clinical Disease Bacteremia Subacute endocarditis Deep tissue abscesses!  Commonly seen with Anaerobic bacteria Diagnostics Enhances anaerobic bacteriagrowth ability Coccoid, pairs and chains α OR β – hemolytic green colour Greening off Catalase NEG, Optochin resistant, Bile solubility NEG Treatment Penicillin or Ceftriaxone is common 65 Enterococci Common Enterococcus faecalis* More common E. faecium* less common most resistant Intrinsic Resistance to Vancomycin: E. casseliflavus & E. gallinarum 66 E. faecium/E. faecalis Epidemiology Worldwide | Transmission – Direct/Droplet Normal flora?  Yes, GI tract noton skin Pathogenesis Opportunistic Virulence: Surface adhesions Hemolysins, proteases, etc. A LOT on intrinsic resistance! treat due to resistance 67 Not as virulent infectious but VERY difficult to  E. faecium/E. faecalis Clinical Disease Bacteremia Common cause Usually seeded from GI tract Endocarditis 2nd most common cause HA-IE 3rd most common cause CA-IE UTIs Associated with indwelling catheters commonly Other rare findings: meningitis, SSTIs, pelvic infections, etc. 68 E. faecium/E. faecalis Diagnosis Gram stain - Coccoid, pairs/chains Media - Blood agar Morphology – Grey, α/γ-hemolytic Biochemicals Catalase NEG PYR POS Growth in 40% bile, high salt/temp PCR E. faecalis E. faecium - γ-H - α-H - grey - opaque 69 Susceptibility Enterococcus spp. have A LOT of intrinsic resistance: Most cephalosporins ex. Cefazolin β-lactams Aminoglycosides Clindamycin Ertapenem TMP-SMX (Septra) 70  Therapy Options Ampicillin (95% E. faecalis are Susceptible BUT