capitis Oral Streptococcal species Viridans group Streptococcus oralis/mitis Streptococcus sanguinis/mutans group Most common cause in CHD.. Difficult to treat due to relative tolerance
Trang 1S hominis
S lugdunensis
S capitis
Oral Streptococcal
species (Viridans
group)
Streptococcus
oralis/mitis
Streptococcus
sanguinis/mutans
group
Most common cause in CHD
Often sensitive to penicillin and third-generation cephalosporin, but resistance to both agents has been observed
Enterococci
E faecalis
E faecium
More common in adults
Difficult to treat due to relative tolerance to β-lactam antimicrobials and increasing
resistance in E faecium.
Nutritionally
variant organism
Abiotrophia spp.
Granulicatella spp.
Difficult to isolate and culture Concerns over relative resistance to β-lactams High relapse rate, need to treat as for enterococcal IE
Other
streptococcal
species
Streptococcus
pneumoniae
Streptococcus
pyogenes
Streptococcus milleri
group
Infrequent but very aggressive cause if IE with severe tissue destruction requiring surgical intervention
HACEK
Haemophilus spp.
Aggregatibacter spp.
Cardiobacterium spp.
Eikenella corodens
Kingella spp.
Affects both prosthetic valves and native valves Generally better prognosis than some causes of IE
Some strains are β-lactamase positive
Hard to grow in laboratory, often require prolonged culture Good pick-up on resected material by molecular methods
Gram negative
Enterobacteriaceae
(Coliforms)
Pseudomonas spp.
More likely in immune-compromised and neonates
Antimicrobial resistance an issue
Specialist advice on combination therapy and length
Fungal Candida spp Cause of both NVE and PVE; very difficult to treat, requiring surgical
resection in most cases, apart from mural IE in neonates
Filamentous fungi Very difficult to manage, almost always requires surgical debridement and aggressive antifungal therapy
Other causes
Bartonella sp.
Coxiella burnetii
Tropheryma whipplei
Mycoplasma spp.
Brucella spp.
Often part of noncultivable or culture-negative endocarditis Serologic testing available for some
Good rate of pick-up on molecular testing of resected material
Combine with epidemiologic exposure for optimal diagnosis
Emerging
pathogens
Mycobacterium
chimaera
M chimaera recently identified as a cause of IE due to contaminated heater cooler units
and bypass circuits used in cardiac surgery
CHD, Congenital heart disease; IE, infective endocarditis; NVE, native valve endocarditis; PVE,
prosthetic valve endocarditis
Trang 2Summary of Pediatric-Specific Cohort Studies Evaluating Changes
in Incidence, Risk Factors and Causative Agents of IE
Study
Time
Period,
Study Type
Number of IE Episodes
% of Patients With Preexisting Cardiac Disease/None
Findings/Comments
Day et
al93
2000 and
2003, US
retrospective
cohort
N = 1588 (causative
organisms in 662 cases)
42%/58% IE episodes with coded organisms, n =
622
■ Staphylococcus aureus, 362 (57%)
■ Viridans Streptococcus, 124 (20%)
■ Coagulase-negative Staphylococcus, 91
(14%)
■ Mortality highest in tetralogy of Fallot with PA and TOF
■ In non-CHD cases, highest mortality in infants, especially premature ones and
with S aureus infections
Gupta et
al94
2000–2010,
US CHD
Retrospective
cohort
N = 3840
estimated
53.5%/46.5% ■ 30.2% no organism (culture negative)
■ S aureus, 36.6% (of those, 46.9% had no
underlying cardiac defect, 28.1% with no defect)
■ Other Staphylococcus spp., 6.5% equally
distributed between those with and without preexisting cardiac defect
■ Viridans Streptococcus, 26% (32.7% in
children with underlying cardiac defects, 17.9% in those without)
■ Trend over study period for increase in streptococcal IE
■ Highest mortality in S aureus IE
Sakai
Bizmark
et al95
2001–2012,
interrupted
time series
retrospective
cohort
N = 3748 (weighted
according to whether IE appears in any primary, secondary, or tertiary discharge code)
50.2%/49.8% ■ Staphylococcus IE, 33.6%
■ Streptococcus, 27.4% (VGS 20.4)
■ Culture negative, 30.4%
■ Main finding was that incidence has not changed but decrease in staphylococcal
and increase in streptococcal IE in the 10-to 17-year-old age group post–2007 guideline
CHD, Congenital heart disease; IE, infective endocarditis; PA, pulmonary atresia; TOF, tetralogy
of Fallot; VGS, viridans group streptococci
Laboratory Diagnostic Procedures
BC remains the gold standard investigation for patients with suspected IE;
however, optimal sampling techniques, volumes (based on age of child), and
Trang 3following volumes and frequency are recommended:
Volumes:
1 Infants and young children: 1 to 3 mL per bottle
2 Older children: 5 to 7 mL per bottle (up to 30 mL blood/day).
Frequency:
1 Three sets of separate venipunctures over 24 hours, ideally with one set
12 hours apart, but with at least the first and last set 1 hour apart
2 If the patient is unstable and presentation is acute, take two BCs at
separate sites immediately and a third at least 1 hour later and
commence empiric therapy as soon as feasible.
New Laboratory Diagnostic Techniques
Techniques such as broad-range bacterial (16S rDNA) and fungal (18s rDNA) polymerase chain reactions (PCRs), pathogen-specific real-time PCRs, and proteomics (matrix-assisted laser desorption/ionization time-of-flight analysis [MALDI-TOF]) have become widely available and should be used in
conjunction with standard culture techniques Gene-specific primers and
amplification are more sensitive and do not always require a sequence step and
so are more rapid.
1 Molecular methodologies can detect bacterial DNA directly in blood, and, although they have advanced in recent years,
■ They are still somewhat insensitive,96 the likely reason due to the low circulating load of bacteria in IE.
■ Broad-range PCR techniques, bacterial (16S rDNA) and fungal (18S rDNA), are designed to amplify both conserved and variable regions of ribosomal DNA but in general are rather insensitive and in addition require a sequencing step to identify the pathogen.
■ Contamination with environmental DNA can be problematic, particularly for fungal 18S DNA Optimal sampling,