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Clinical relevance of blood-culture for anaerobes

Clinical relevance of blood-culture for anaerobes. Elisabeth Nagy MD, PhD, DSc Institute of Clinical Microbiology, Faculty of Medicine, University of Szeged, Hungary 5th ESCMID School Santander, 10-16 June, 2006. Changing concept of sepsis. Earlier concept of sepsis :

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Clinical relevance of blood-culture for anaerobes

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  1. Clinical relevance of blood-culture for anaerobes Elisabeth Nagy MD, PhD, DSc Institute of Clinical Microbiology, Faculty of Medicine, University of Szeged, Hungary 5th ESCMID School Santander, 10-16 June, 2006

  2. Changing concept of sepsis Earlier concept of sepsis: - detectable primary focus of the infection + - positive blood cultures Sepsis (new definition since 1992): - SIRS (systemic inflammatory response syndrome), which is an acute physiological response to any insult - sepsis if SIRS is caused by infection - septic shock: hypotension, perfusion abnormalities - severe sepsis organ dysfunctions, hypotension - multiple organ dysfunction syndrome (MODS) requires rapid intervention for prevention of homeostasis

  3. In sepsis a series of events occurs Infection SIRS Sepsis Sever sepsis infection+SIRS infec.+SIRS+hypoperfusion -cardiovascular (SHOCK) -renal -ARDS -icterus -CNS -lactacidaemia -metabolic acidosis - temperature <36 or >38oC - pulse rate > 90 bpm - respiratory rate >20/min or hyperventilation - WBC <4 000/mm3 or >12 000 mm3 MODS

  4. Mortality in sepsis • SIRS 5-7% • Sepsis 10-15% • Sever sepsis 20-25% • Septic shock 40-60%

  5. Types of bloodstream infections • Bacteraemia / fungaemia • Transient • mechanical or surgical manipulation of infected tissue • tooth brushing or bowel movements • Intermittent • typically seen with undrained abscesses • localized infections such as pneumonia, urinary tract infection CNS infection • Continuous • intravascular infections such as infective endocarditis, septic thrombophlebitis, mycotic aneurysm

  6. Transient bacteraemia after tooth extraction involving anaerobes • Important in patients with artificial valves or having vitium and for patients with no hart problems as case of distant infections • 47 patients were involved • Blood samples were taken after 10 minutes of the extraction. • 35 patients had transient bacteraemia. 28 of them had poor or medium oral hygiene Blood culture results Number of patients Only aerobes 2 Only anaerobes 15 Aerobes + anaerobes 18 All with positive blood culture 35 Szonthág, Méray, Nagy (1994)

  7. Transient bacteraemia after tooth extraction involving anaerobes • Two blood culture systems were compared • Oxoid Signal system • Bio-Merieux Vital system Blood culture results Percentage of all patients Negative in both systems 26% Positive in both systems 42% Positive only in Bio-Merieux system 28% Positive only in Oxoid system 4% No. of anaerobic isolates in Oxoid system : 27 isolates No. Of anaerobic isolates in bio-Merieux system: 50 isolates

  8. Bacteraemia after plate removal and tooth extraction (Rajasou et al.: 2004) • 6 of 10 patients had at least 10 minutes after extraction transient bacteraemia. • 4 had only anaerobic bacteria and 2 aerobic and anaerobic bacteria • Altogether 14 different species were isolated 12 anaerobes and 2 aerobes The mortality rate of anaerobic endocarditis is 21-43% (Brook 2002) bacteria involved most frequently are anaerobic cocci, P. acnes, B. fragilis

  9. The best way to detect bloodstream infection is to carry out blood cultures Traditional systems

  10. Automated blood culture systems

  11. Anaerobic infections • ”Classical” infections caused by clostridia • exogenous • clinical diagnosis • ”Modern” infections caused by non-spore-forming anaerobes • endogenous • mixed infection • normal flora members are involved

  12. The ”golden” era of anaerobes (1960-80) Recognition of the role of non-spore forming anaerobes in severe infections Understanding the role of anaerobes in the normal flora Incidence of anaerobes in bacteraemia:5-15%(Finegold 1977, Brook 1989) B. fragilis group : 60-75% Clostridium spp: 10-20% Peptostreptococcus spp: 10-15% Fusobacterium spp: 10-15% P. acnes: 2-5% ???? Dr. Sydney Finegold at work in an anaerobic chamber in 1960s

  13. Decrease of the incidence of anaerobes in bloodstream infections • Decreased enthusiasm about anaerobes world-wide, but especially in the US • Due to the cost of the procedures • Due to time-consuming methods • Increased use of metronidazole (and other anti-anaerobic antibiotics) for prophylaxis • Potent antibiotics were developed for empiric treatment of infections involving anaerobes • Development in surgical procedure and more understanding about situation where anaerobes can be potential pathogens

  14. Do we need anaerobic blood cultures ? CONS Low incidence of positivity • Ortiz et al. 2000: Routine use of anaerobic blood cultures: are they still indicated? • During a 3-year period 0.4% of the patients with a positive blood culture had true anaerobic bacteraemia • All 7 patients with anaerobic bacteraemia had an obvious source of anaerobic infection • Gené et al. 2005: Value of anaerobic blood cultures in paediatrics • During 2 year period 9,165 paediatric blood samples were processed 497 (5.4%) overall positivity and 2 (0.02%) positive for anaerobe • Lee at al. 2000: The assessment of anaerobic blood culture in children • During 4 year period 9886 paired blood cultures in children • 618 aerobic isolates and 3 anaerobic isolates

  15. Do we need anaerobic blood cultures ? CONS • Chandler et al. 2000: Re-evaluation of anaerobic blood cultures in a veteran population • 5-year retrospective study • 22,175 anaerobic blood cultures, significant anaerobic bacterium was isolated only in 0.14% • in 92% of these patients anaerobic infection could be suspected • selective rather than routine use of anaerobic blood culture in a veteran population • Senda et al.: Anaerobic bacteraemia: the yield of positive anaerobic blood cultures: patient characteristics and potential risk factors • During a two year period in Japan 34/6,215 university hospital patients and 35/838 community hospital patients had an anaerobic bacteraemia • Because of the low positivity anaerobic blood cultures should be used selectively

  16. Do we need anaerobic blood cultures ? PROS • Clinical significance and outcome of anaerobic bacteraemia (Salonen JH, Eerola E, Meurman O: CID 1998) • The study was carried out in Turku (Finland), University hospital which is a 1000-bed tertiary-care teaching hospital • Between 1991 and 1996 40 000 blood cultures were performed • 5% overall positivity • 81 patients 111 samples (4% of all positive blood cultures) yielded anaerobic bacteria • 0.18 cases / 1,000 admission • 21 patients had >2 blood cultures positive for the same anaerobic bacterium • 4 patients had multiple anaerobes in their blood cultures • Most common isolates: Bacteroides (57%) > Peptostreptococcus (11%) > Clostridium (10%)

  17. Clinical significance and outcome of anaerobic bacteraemia(Salonen JH, Eerola E, Meurman O: CID 1998) Blood cultures positive for anaerobes 81 patients Clinically insignificant bacteraemia 24 patients Clinically significant bacteraemia 57 patients Initial treatment effective 28 patients (49%) Initial treatment ineffective, not changed 11 patients (19%) Initial treatment ineffective, changed to affective 18 patients (32%) Died 5 patients (18%) Died 6 patients (55%) Died 3 patients (17%)

  18. Do we need anaerobic blood cultures ? PROS • Several unusual case reports prove the importance of isolation anaerobes from blood: • O’Donnell et al: Bacteroides fragilis bacteraemia and infected aortic aneurysm presenting as fever of unknown origin: diagnostic delay without routine anaerobic blood cultures. (1999) • Ha G.Y. et al: Case of sepsis caused by Bifidobacterium longum. (1999) • Matsukawa et al.: Multibacterial sepsis in an alcohol abuser with hepatic cirrhosis. (2003) (B. thetaiotaomicron, F. mortiferum, S. constellatus) • Elsaghier et al.: Bacteraemia due to Bacteroides fragilis with reduced susceptibility to metronidazole (2003) • Candoni et al.: Fusobacterium nucleatum: a rare cause of bacteraemia in neutropenic patients with leukemia and lymphoma (2003) • C. septicum positive blood culture is strongly associated with neutropenic colitis and colonic malignancy (G.P Bodey 1991) • Etc.

  19. Use of molecular techniques to improve identification of anaerobic bacteria originating from blood • Lau et al.: Anaerobic, non-sporulating, Gram-positive bacilli bacteraemia characterized by 16S rRNA gene sequencing. Journal of Medical Microbiology 2004. • 165 blood culture isolates of anaerobic Gram-positive bacilli were tested • 51 C. perfringens • 75 P. acnes • the remaining 39 isolates were subjected to 16S rRNA sequencing: • Clostridium spp (17), Eggerthella spp (10), Lactobacillus spp (8), Eubacterium tenue (2), Olsenella uli (1), Bifidobacterium pseudocatenulatum (1) • Out of these 39 isolates 36 was considered clinically significant. conventional method

  20. Clinically significant anaerobic bloodstream infections in our University Hospital Tercier-care hospital with 1314 beds 2004 2005 2006 (I-V months) Total no.of bloodculture sets 3320 5432 2560 No. of positive anaerobic bottles 49 72 33 No. of clinically relevant anaerobe isolate 24 25 20 No. of patients with anaerobic 19 (1)* 18 9 (1)* bloodstream infection Case/1000 hospital admission 0.06 0.1 0.08 *No. of patients with polymicrobial anaerobic bloodstream infection

  21. Distribution of anaerobic species among positive patients 2004 2005 2006 B. fragilis B. fragilis B. fragilis B. ovatis B. capillosus B. capillosus B. thetaiotaomicron F. nucleatum F. necrogenes B. uniformis Pr. denticola Prevotella sp B. urealyticus Pr. oralis C. perfringens Pr. oralis A. meyeri Micromonas micros F. nucleatum C. carnis Pst. assacharolyticus C. perfringens C. innocuum P. acnes ??? A. meyeri C. perfringens A. odontolyticus Clostridium sp E. lentum L. acidophilus Micromonas micros Pst. assacharolyticus P. acnes ??? V. parvula P. acnes ???

  22. Propionibacterium spp isolated from blood culture Real pathogen ? colonizer ? contaminant (quantitative microbiology is needed to distinguish)

  23. Primary infections of proven P. acnes aetiology(in previously healthy individuals) • Purulent folliculitis distinct from acne vulgaris (Maibach, 1967) • Acute meningitis (Schlessinger, 1977) • Acute osteomyelitis (Suter et al., 1992) • Primary infections of eye • endophthalmitis (acute / chronic) - canaliculitis • conjunctivitis - peri-orbital cellulitis • blepharitis - abscesses • keratitis

  24. Secondary or opportunistic infections caused by P. acnes • Rare (USA hospital: 94 proven infections in 10 years, Brook et al., 1991) • Predisposing conditions: • foreign bodies • diabetes • previous surgery • invasive diagnostic procedure • immunodeficiency or immunosupression • malignancy • Most frequently observed infections: • abscess formation, • meningitis due to CNS shunt • osteomyelitis, arthritis, endocarditis

  25. Gram-negative anaerobic bacteria induce cytokines (Szöke, Nagy, Mandy, Kocsis 1997) • Different Bacteroidesspecies were isolated from infections • Human mononuclear cells and whole blood cultures were used for the induction • TNF release was detected by the WEHI 164 bioassay • IL-6 production was detected by the B-9 bioassay • Besides the whole cells of anaerobic bacteria, isolated LPS was also used in the induction experiments

  26. TNF levels measured by bioassay in the supernatants of human mononuclear cells stimulated with heat-killed S. aureus and B. fragilis Nagy et al.: Anaerobe 1998

  27. Induction of TNF and IL-6 by LPS of B. fragilis and E. coli Amount of TNF (U/ml) IL-6 (pg/ml) MN cells whole blood MN cells whole blood B. fragilis LPS 1x102 5x102 1x105 1x105 E. coli LPS 2.5x102 7.5x102 1x106 1x106 B. fragilis was a clinical isolate obtained from an abscess Anaerobes can easily be involved in the development of sepsis !!

  28. Conclusions 1. • Risk factors for anaerobic bacteraemia • Elderly age • Haematological malignancy with or without therapy, such as febrile neutropenia, bone marrow transplant recipients • Solid tumour as underlying disease • Underlying disease in the gastrointestinal tract • Poor oral hygiene • Same facultative anaerobic bacteria grow better in the anaerobic bottle that in the aerobic one (earlier detection)

  29. Conclusions 2. • Increasing number of publications proves the presence of anaerobic bacteraemia during FUO • Uncommon anaerobic infections may result in bacteraemia (diabetic foot ulcer, oral cancer, Lemmier’s syndrome, etc.) • Antibiotics used for empiric treatment of anaerobic mixed infections may fail to treat the patients due to antibiotic resistance in anaerobes (Bacteroides fragilis and related species)

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