Hacek

HACEK group of infection, causing endocarditis and their lab diagnosis

1. HACEK Group of Infections Dr Vishal Kulkarni MBBS MD (Microbiology)

2. The acronym HACEK refers to a group of fastidious slow growing bacteria, normally resident in the mouth, which can sometimes cause severe infections, particularly endocarditis. Introduction

3. Haemophilus species- They are H. parainfluenzae , H. aphrophilus & H.paraphrophilus H. parainfluenzae - B eside endocarditis causes bacteremic epiglotitis , bronchitis, sinusitis, otitis media, COPD, pneumonia, empyma , brain abscess, vertebral osteomyelitis, neonatal sepsis . Joint infections, genital & biliary tract infection, H. aphrophilus & paraprophilus - Minor component of healthy periodontal flora. Causes endocarditis, head & neck infections, haematogenous disseminated infections, abdominal infections & wound infections. Immunocompromised state is predisposing factor

4. Sample collection & transport- Preparation of site Antisepsis Precautions Specimen volume -Adult -Children Number of blood cultures Timing of collection Transport

5. Lab Diagnosis- Gram stain- -small, pale staining gram negative coccobacilli . Culture- Grows on chocolate agar & Haemophilus isolation agar ( X & V factors) Temp-35°C,in moist environment with 3-5% CO₂. Colonies of H. Parainfluenzae are small, light grey & matt appearance. Colonies of H. aphrophilus & H. paraphrophilus are convex, granular & have yellowish pigment

6. H. parainfluenzae colonies H. a phrophilus & paraphrophilus colonies

7. H. parainfluenzae & H. paraphrophilus require only V factor for growth. H. aphrophilus requires the X factor . T his principle can be used in identification of these species. Staphylococcal Streak Technique- Satellitism . ALA Porphyrin agar method δ -ALA- porphyrin disc method Biochemical reactions- Oxidase + ve Catalase – ve Produces acid from sugars ALA test + ve .

8. Staphylococcal streak technique Growth of haemophilus aphrophilus sp . on Trypticase soy agar

9. ALA Porphyrine agar method for H. parainfluenzae δ -ALA disc method for H. parainfluenzae

10. Antimicrobial susceptibility test- These 3 species are generally susceptible to- 3 rd generation cephalosporins Quinolones Tetracyclines Aminoglycosides.

11. Actinobacillus actinomycetemcomitans - Is a part of normal flora of oral cavity, particularly in gingival, supragingival crevices. Is a/w actinomycotic infections, endocarditis, bacteremia, wound infection, dental infections. Native valve endocarditis occurs in individuals with prior valve damage. Complications - pericarditis, paraventricular abscess, CCF, septic emboli, hematogenous dissemination. Predisposing factors - poor dentition, recent dental manipulation

12. Clinical features- Fever, weight loss, chills, cough, night sweats are common along with heart murmur. Hepatosplenomegaly , splinter haemorrhages . Localized OR Generalized juvenile periodontitis. May cause severe head & neck infections

13. Gram stain- Pale staining Gram negative coccobacilli Cultural characteristics- Grows slowly on chocolate agar Colonies are small, smooth, transluscent , nonhemolytic & have slightly irregular edges. Lack of growth on Mac Conkey & other enteric agar. Biochemical Reactions- Oxidase - ve Catalse + ve Acid from sugars

14. Molecular methods- Polyacrylamde Gel Electrophoresis Antimicrobial susceptibility test- Sensitive to 3 rd generation cephalosporines Fluoroquinolones Tetracycline, doxycycline, azithromycine , septran , rifampin, aminoglycosides T/t for periodontal disease - Subgingival debridement, scaling, root canal with antimicrobial therapy.

15. Cardiobacter hominis - Is a part of normal respiratory tract flora . Enters blood stream & attacks previously damaged heart valves Poor dentition & recent dental procedures are predisposing factors. Forms large friable vegetations in endocarditis. Complications- embolisation , mycotic aneurysm, CCF

16. Cultural charactristic & identification- Grow slowly with no visible change in subculture. Forms small opaque glistening colonies after 48 hrs at 35°C in 5-7% CO₂. Gram stain from colonies reveales gram variable organism with tendency to retain crystal violet at ends.( ‘ teardrop’ or ‘ dumbell shaped’ ) Biochemical reactions- Oxidase + ve Catalase, nitrate & urease - ve . Indole + ve Produce H₂S & acid in TSI.

17. Antimicrobial susceptibility test- Susceptible to most antibiotics like p enicilline , ampicilline , 3 rd Generation cephalosporines , imipenem , meropenem , fluoroquinolones , aminoglycosides. For endocarditis, recommended T/t is third generation cephalosporines .

18. Eikenella Corrodenes It is a part of mouth & upper respiratory tract. Plays role in periodontal diseases, oral infections (gingivitis, periapical abscess, root canal infections). Other infections includes ocular infections, head neck infections, pleuropulmonary infections, intraabdominal infections & skeletal infections. E. corrdenes bacteremia & endocarditis are seen in immunocompromised pts , IV drug abusers, individuals with previously valvular damage & recent dental work.

19. Cultural characteristics & identifiation - Grows on both blood & chocolate agar but not on Mac Conkey agar. Colonies are small grey moist & may ‘pit’ the agar. On G ram stain from colonies, they are regular GNB & not seen like coccobacilli . Biochemical reactions- Oxidase + ve Catalase – ve Reduces nitrates to nitrites They are asaccharolytic Lysine & ornitine decarboxylase positive.

20. Eikenella corrodenes colonies

21. Molecular methods- For detection, identification & typing of E. corrodens . Done with specific DNA probes for gingivitis, periodontitis. Epidemological methods include SDS-PAGE, Pulse field gel electrophoresis, PCR, restriction endonuclease analysis.

22. Antimicrobial susceptibility- Susceptible to ampicilline , amoxicilline , tetracyclines , imipenem , meropenem . A re resistant to penicillinase resistant penicillins , clindamycin, vancomycin, erythromycin, metronidazole & aminoglycosides. Most isolates are susceptible to 1 st generation cephalosporines with cephazoline being most active & also to 3 rd generation cephalosporines .

23. Kingella kingae Although they are part of normal upper respiratory & genitourinary tract flora of humans, they are increasingly recognised as human pathogens. Besides endocarditis, causes bacteremia & osteoarticular infections in pediatric patients . Age group - 6months to 4 years. K . Kingae has essentially replaced H. influenzae as the most common GNBs causing osteoarticular infections in kids less than 3 yrs of age.

24. They also cause Bone & joint infections Osteomyelitis of long bones Bacteremia CVS complications d/t endocarditis (pericarditis, pericardial abscess, mycotic aneurysm, infarction, CCF) Predisposing factors- Poor oral hygiene, pharyngitis, dental manipulation, immunocompromised states.

25. Gram stain – Plump, short, gram negative coccobacilli . Cultural characteristics- Grows slowly on chocolate & blood agar but not on Mac Conkey agar. Grows selectively on trypticase soy agar (contains 5-7% sheep blood & vancomycin 2ug/ml) Biochemical reactions- Oxidase + ve Catalase - ve Acid from glucose & maltose

26. PCR can be used for direct detection of kingella kingae in joint fluid. Antimicrobial susceptibility- Are susceptible to penicillin, ampicillin, oxacillin , all generation cephalosporins , chloramphenicol, aminoglycoside & septran . Resistant to erythromycin, clindamycin & vancomycin.

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