Clinical relevance of bloodculture for anaerobes

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.SIRShypoperfusion -cardiovascular
(SHOCK) -renal -ARDS -icterus -CNS -lactacidaemia
-metabolic acidosis
- temperature lt36 or gt38oC - pulse rate gt 90
bpm - respiratory rate gt20/min or
hyperventilation - WBC lt4 000/mm3 or gt12 000 mm3
MODS
4
(No Transcript)
5
Mortality in sepsis

• SIRS 5-7
• Sepsis 10-15
• Sever sepsis 20-25
• Septic shock 40-60

6
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

7
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)

8
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

9
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
10
The best way to detect bloodstream infection is
to carry out blood cultures
Traditional systems
11
Automated blood culture systems
12
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

13
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 Fusobacteriu
m spp 10-15 P. acnes 2-5 ????
Dr. Sydney Finegold at work in an anaerobic
chamber in 1960s
14
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

15
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

16
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

17
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 gt2 blood cultures positive for
  the same anaerobic bacterium
• 4 patients had multiple anaerobes in their blood
  cultures
• Most common isolates
  
• Bacteroides (57) gt Peptostreptococcus (11) gt
  Clostridium (10)

18
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)
19
Do we need anaerobic blood cultures ? PROS

• Several unusual case reports prove the importance
  of isolation anaerobes from blood
• ODonnell 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.

20
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
21
Clinically significant anaerobic bloodstream
infections in our University Hospital

• Tercier-care hospital with 1314 beds
• 2004 2005 2006 (I-V months)
• Total no. of blood culture 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

22
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 ???

23
Propionibacterium spp isolated from blood culture

• Real pathogen
• ?
• colonizer
• ?
• contaminant
• (quantitative microbiology is needed to
  distinguish)

24
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

25
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

26
Gram-negative anaerobic bacteria induce cytokines
(Szöke, Nagy, Mandy, Kocsis 1997)

• Different Bacteroides species 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

27
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
28
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 !!

29
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)

30
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,
  Lemmiers 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)