A clinically orientated procedure for the workup of anaerobic bacteria in the era of MALDI-TOF: feasible or fiction?

A clinically orientated procedure for the workup of anaerobic bacteria in the era of MALDI-TOF: feasible or fiction? Author: apr. Bart Peeters Supervisor: dr. Reinoud Cartuyvels Date: 19/05/2015

Content of this presentation Introduction Questions and methods a. Survey on anaerobic identification, reporting and AST procedures b. Multi-center retrospective case study of anaerobic cultures General conclusions To do/actions

Introduction Pathogenic role well established but often neglected Varying interest in anaerobic microbiology: 1960s: 1970s: 1980s: 2010s: Introduction of MALDI-TOF: Revolution -> Increasing amount of reported species and unfamiliar organisms -> Ignoring clinically significant results? -> Over-treating insignificant results?

Content of this presentation Introduction Questions and methods a. Survey on anaerobic identification, reporting and AST procedures b. Multi-center retrospective case study of anaerobic cultures General conclusions To do/actions

Questions and methods How do Belgian laboratories organize anaerobic ID, reporting and AST procedures? Web-based survey Are clinical decisions influenced by anaerobic culture results? Multi-center retrospective case study

Content of this presentation Introduction Questions and methods a. Survey on anaerobic identification, reporting and AST procedures b. Multi-center retrospective case study of anaerobic cultures General conclusions To do/actions

a. Survey on anaerobic identification, reporting and AST procedures 53 questioned laboratories (response degree 64%): Q1: From which samples do you perform anaerobic cultures? Q2: Do you use other rejection criteria besides sample type for performing anaerobic culture? Q3: In which documents do you mention rejection criteria for anaerobic culture? Q4: Do you use specific anaerobic collection or transport media? Q5: When do you perform a full identification (species level) of cultured anaerobic colony types? Q6: What is reported to the clinician if limited workup of an anaerobic culture is applied? Q7: Which identification methods are available for anaerobic bacteria in your laboratory? Q8: Which identification method is used for the vast majority of anaerobic bacteria? Q9: When do you report a full identification (species level) of strictly anaerobic bacteria to the clinician? Q10: When do you perform an anti-microbial susceptibility test for strictly anaerobic bacteria? Q11: On which agar do you perform susceptibility testing for strictly anaerobic bacteria? Q12: Which method is used for testing susceptibility of strictly anaerobic bacteria? Q13: Which breakpoints do you use for the interpretation of anaerobic susceptibility testing? Q14: Which anti-microbial agents do you test for anaerobic bacteria? Q15: Do you use non-selective reporting for tested anti-microbial agents? Results and literature review will be discussed

Number a. Survey on anaerobic identification, reporting and AST procedures Q1: From which samples do you perform anaerobic cultures? Results 28 26 24 22 20 18 16 14 12 10 8 6 4 2 0 Always, even if not requested by the clinician If not requested, depending on the clinical context after contacting the clinician Only if requested by the clinician Only if requested by the clinician with additional information Never/Rejection -> Generally accepted sample types for anaerobic culture (rejection 10%)

Number a. Survey on anaerobic identification, reporting and AST procedures Q1: From which samples do you perform anaerobic cultures? Results 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 0 Always, even if not requested by the clinician If not requested, depending on the clinical context after contacting the clinician Only if requested by the clinician Only if requested by the clinician with additional information Never/Rejection -> Generally rejected sample types for anaerobic culture (rejection 50%)

Number a. Survey on anaerobic identification, reporting and AST procedures Q1: From which samples do you perform anaerobic cultures? Results 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Broncho-alveolair lavage Middle ear swab Middle ear aspirate Superficial wound aspirate/biopsy Always, even if not requested by the clinician If not requested, depending on the clinical context after contacting the clinician Only if requested by the clinician Only if requested by the clinician with additional information Never/Rejection -> Different opinions exist for these sample types (10% < rejection > 50%)

a. Survey on anaerobic identification, reporting and AST procedures Q1: From which samples do you perform anaerobic cultures? Literature and guidelines 4 important questions (Garcia): 1. Correct sample type? 2. Relevant body site?

a. Survey on anaerobic identification, reporting and AST procedures Q1: From which samples do you perform anaerobic cultures? Literature and guidelines 4 important questions (Garcia): 3. Correct transport device? 4. Transported timely?

a. Survey on anaerobic identification, reporting and AST procedures Q5: When do you perform full ID (species level) of anaerobic colony types? Results Absolute number (%) A full identification is carried out depending on the anatomical origin of the sample 19 (56) A full identification is carried out depending on the number of anaerobic colony types A full identification is carried out of every colony type of which there is a strong suspicion that it is a strictly anaerobic bacteria (comparing aerobic and 13 (38) 13 (38) A full identification is carried out depending on the total ratio of aerobic and anaerobic colony types 6 (18) Other 3 (9) A full identification is carried out of every anaerobic colony type 1 (3)

a. Survey on anaerobic identification, reporting and AST procedures Q5: When do you perform full ID (species level) of anaerobic colony types? Literature and guidelines Pure anaerobic cultures or samples from anatomically sterile sites: CONSENSUS to identify all anaerobic colony types (Garcia; Wadsworth; CLSI M56A) Serious infections: CONSENSUS to identify all anaerobic colony types (Cumitech; Citron et al.; CLSI M56A) Poly-microbial cultures or cultures from non-sterile body sites samples: NO CONSENSUS -> Suggested workup schemes based on Gram stain, biochemical systems and/or rapid disk and spot tests (Baron et al.; Garcia) Using MALDI-TOF: less justifiable to limit anaerobic identifications? -> Figure out workup schemes centralizing MALDI-TOF method -> Introducing restrictive reportage

a. Survey on anaerobic identification, reporting and AST procedures Q9: When do you report full ID of strictly anaerobic bacteria to the clinician? Results Absolute number (%) The full identification is reported depending on the anatomical origine of the sample 18 (53) The full identification is reported depending on the kind of isolated strictly anaerobic bacteria 14 (41) The full identification is reported depending on the number of isolated strictly anaerobic bacteria 14 (41) The full identification is always reported to the clinician 10 (29) The full identification is reported depending on the total ratio of isolated anaerobic and strictly anaerobic bacteria 6 (18) Other 3 (9)

a. Survey on anaerobic identification, reporting and AST procedures Q9: When do you report full ID of strictly anaerobic bacteria to the clinician? Results Which fully identified anaerobic bacteria would you certainly report? (n=14) Absolute number (%) Clostridium species (histolyticum, novyii, perfringens, septicum, sordelii, tertium, botulinum, tetani) Bacteroides fragilis group Fusobacterium species (necrophorum, nucleatum, mortiferum, avium) Actinomyces species Prevotella species (disiens, bivia, dentalis, melaninogenica) Bacteroides non-fragilis group 12 (86) 12 (86) 11 (79) 11 (79) 10 (71) 10 (71) Propionobacterium species 9 (64) Gram positive cocci 2 (14)

a. Survey on anaerobic identification, reporting and AST procedures Q9: When do you report full ID of strictly anaerobic bacteria to the clinician? Literature and guidelines No validated standards for reporting anaerobic bacteria Existing reporting strategies based on knowledge of local and international experts No answer on how and what to report from anaerobic cultures in literature and guidelines Isolation, identification and reportage of anaerobic bacteria justified: 1. Information about potential primary site of infection ( sample origin?) 2. Information about potential resistance ( when performing AST?) 3. Information about virulence ( species matters)

a. Survey on anaerobic identification, reporting and AST procedures Q10: When do you perform AST for strictly anaerobic bacteria? Results Absolute number (%) Depending on the kind of isolated strictly anaerobic bacteria Depending on the anatomical origine of the sample Depending on the number of isolated strictly anaerobic bacteria 13 (38) 13 (38) 10 (29) Always 6 (18) Never Depending on the total ratio of isolated anaerobic and strictly anaerobic bacteria 4 (12) 4 (12) In consultation 2 (6) Depending on clinical data 1 (3)

a. Survey on anaerobic identification, reporting and AST procedures Q10: When do you perform AST for strictly anaerobic bacteria? Results From which anaerobic bacteria would you certainly perform AST? (n=13) Absolute number (%) Bacteroides fragilis group Fusobacterium species (necrophorum, nucleatum, mortiferum, avium) Bacteroides non-fragilis group 11 (85) 9 (69) 9 (69) Prevotella species (disiens, bivia, dentalis, melaninogenica) 7 (54) Clostridium species (histolyticum, novyii, perfringens, septicum, sordelii, tertium, botulinum, tetani) 6 (46) Actinomyces species 5 (38) Propionobacterium species 4 (31) In consultation 2 (15)

a. Survey on anaerobic identification, reporting and AST procedures Q10: When do you perform AST for strictly anaerobic bacteria? Literature and guidelines Major indications for anaerobic AST (CLSI M11-A8): 1. Known resistance of a particular organism or species 2. Persistence of the infection despite adequate treatment with an appropriate therapeutic regimen: manageable? 3. Difficulty in making empirical decisions based on precedent cultures 4. Confirmation of appropriate therapy for severe infections or for those that may require long-term therapy

a. Survey on anaerobic identification, reporting and AST procedures Q10: When do you perform AST for strictly anaerobic bacteria? Literature and guidelines Periodic monitoring of resistance (CLSI M11-A8; Wybo et al.): Resistance especially in Bacteroides and Parabacteroides spp. Amoxicillin-clavulanic acid, piperacillin-tazobactam, meropenem and metronidazole suitable for empirical use Penicillin, clindamycin and moxifloxacin not suitable for empiric use Unclear correlation between in vitro susceptibility and clinical response (Brook et al.; Hecht et al): Cure without antibiotics or surgery Cure with surgery Cure with eradication of the aerobic component in poly-microbial infections

Content of this presentation Introduction Questions and methods a. Survey on anaerobic identification, reporting and AST procedures b. Multi-center retrospective case study of anaerobic cultures General conclusions To do/actions

b. Multi-center retrospective case study of anaerobic cultures Demonstrated clinical impact of anaerobic culture results in Bacteroides fragilis bacteremia (Redondo et al; Nguyen et al.; Salonen et al.; Robert et al.) Clinical impact of anaerobic culture results other than blood unclear -> no studies evaluating body fluids, biopsies, abscess drainages, Multi-center retrospective case study conducted: 1. How long does it take to report ID and AST results of anaerobic cultures to clinicians? 2. Is therapy influenced by anaerobic culture reporting practices? 3. Is patient outcome influenced by anaerobic culture reporting practices?

b. Multi-center retrospective case study of anaerobic cultures 7 hospital laboratories documented anaerobic cultures between February 16 and April 5 Inclusion criteria for samples: 1. Aspirate, drainage, biopsy, sterile fluid, surgically obtained deep swabs 2. Anaerobic growth on lab report 3. First isolation of anaerobic bacteria Anonymized reports and coded survey forms 51 relevant samples from 49 different patients

Number b. Multi-center retrospective case study of anaerobic cultures General results Sample types and origin (n=51): 14 12 10 17 deep swabs (33%) 27 aspirates (53%) 8 6 4 2 0 7 tissues (14%)

Number b. Multi-center retrospective case study of anaerobic cultures General results Number of reported species per sample (n=51): 14 12 10 8 6 4 2 0 one two anaerobic anaerobic bacteria bacteria three anaerobic bacteria four aerobic bacteria three aerobic bacteria two aerobic bacteria one aerobic bacteria no aerobic bacteria

Number b. Multi-center retrospective case study of anaerobic cultures General results Isolated anaerobic bacteria (n=63): 14 12 10 8 6 4 2 0

Number b. Multi-center retrospective case study of anaerobic cultures General results Isolated aerobic bacteria (n=93): 25 20 15 10 5 0

Number Number b. Multi-center retrospective case study of anaerobic cultures 1. How long does it take to report ID and AST results of anaerobic cultures to clinicians? 35 30 25 20 15 10 5 0 Reporting time anaerobic bacteria Reporting time ID Reporting time AST Late anaerobic reportage : ID > day 5 AST > day 7 60 50 40 30 20 10 0 Reporting time aerobic bacteria Reporting time ID Reporting time AST Late aerobic reportage : ID > day 3 AST > day 4

b. Multi-center retrospective case study of anaerobic cultures 2. Is therapy influenced by anaerobic culture reporting practices? Anti-microbial therapy in 49 patients: - 7 unknown - 4 none - 38 anti-microbial therapy Documented anti-microbial therapy in 38 patients: - In 7 patients (18%) therapy adjusted based on anaerobic culture results - In 10 patients (26%) therapy adjusted based on aerobic culture results - In 29 patients (76%) empirical therapy whiteout changes afterwards Anaerobic culturing results reported early, completely and with AST results Anaerobic culturing results not reported early, completely or with AST results Anti-microbial therapy not adjusted based on anaerobic ID or AST 15 20 Anti-microbial therapy adjusted based on anaerobic ID or AST 6 1 28% 5% χ 2 -test: p = 0,04

b. Multi-center retrospective case study of anaerobic cultures 3. Is the outcome of patients with anaerobic infections affected by results of anaerobic cultures? 42 (86%) Patient outcome 1 (2%) 3 (6%) 3 (6%) Discharged Still hospitalized with anti-anaerobic therapy Still hospitalized without anti-anaerobic therapy Died Anaerobic culturing results reported early, completely and with AST results Anaerobic culturing results not reported early, completely and with AST results Patient died 2 1 Patient survived 21 25 9% 4% χ 2 -test: p = 0,41

Content of this presentation Introduction Questions and methods a. Survey on anaerobic identification, reporting and AST procedures b. Multi-center retrospective case study of anaerobic cultures General conclusions To do/actions

General conclusions a) Survey on anaerobic identification, reporting and AST procedures: No uniform Belgian laboratory approach concerning anaerobic microbiology practices Suggested evidence-based clinically orientated work-up centralizing MALDI-TOF

General conclusions b) Multi-center retrospective case study of anaerobic cultures: Little use of anaerobic culture results observed Anti-microbial therapy adjusted significantly more, based on anaerobic culture results if reportage was early, completely and with AST Impact on patient outcome, duration of hospitalization or antimicrobial therapy not demonstrated Cave: impact of negative culture result not assessed in this study

Content of this presentation Introduction Questions and methods a. Survey on anaerobic identification, reporting and AST procedures b. Multi-center retrospective case study of anaerobic cultures General conclusions To do/actions

To do/actions Implementation of the clinically orientated workup of anaerobic cultures using MALDI-TOF Continuation of the multi-center retrospective case study in order to demonstrate clinical impact of anaerobic cultures? Literature follow-up ESCMID Study Group for Anaerobic Infections (ESGAI) interested in these results