Transcript S. aureus nasal carraige

S. aureus nasal carraige
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Post – operative wound infection
Pneumonia
Line infection
CAPD/HD infection
Infections in immunocompromised host
Kluytmans, J. Infect Dis 1995; 171:216
Majority of infections are
endogenous
Weinstein, NEJM 1959; 260: 1303
Luzar, NEJM 1990; 322: 505
Yu, NEJM 1986; 315:91
Von Eiff; NEJM 2001; 344: 11
Staph aureus nasal carraige
• Nasal carraige appears to be natural
ecologic niche, though axilla and
groin/perineum can also be common
 Elimination from nares appears to result in
subsequent disappearance from other sites
Moss, Lancet 1948; 1: 320
Noble, J Hyg (lond) 1967; 65: 567
Doebbeling, J Chemother 1994; 6 (supple 2):11
Casewell, J Antimicrob Chemother 1986; 17: 365
Reagan, Ann Intern Med 1991; 114: 101
Longitudinal surveys of Staph aureus carraige
in healthy adults
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Nasal carraige in 20-55%
Persistent carraige: 10-35%, often same clone
Intermittent carraige: 20-75%, dif. clones
Never carry: 5-50%
More common in children, reasons for pattern
shift unknown
Gould, J Hyg (lond) 1954; 52: 304. Hu; J Med Microbiol 1995; 42: 127
Armstrong-Esther, Ann Hum Biol 1976; 3: 221. Goslings, Arch Int Med 1958; 102: 691
Hoffler, Med Microbiol Immunol 1978; 164: 285. Maxwell , Am J Surg 1969; 118: 849
Riewerts Eriksen, 1995; 115:51
Persistent carraige
• Higher numbers than in intermittent carriers
• Persistent carraige seems to exclude other
staph strains as clone is stable. Better
match, specific receptors?
• 2 quantitative cultures needed to predict
carrier state
• 7 cultures needed to discern none vs
intermittent carriers (Nouwen, 2001)
Bacterial Determinants of S.aureus Nasal
Carraige
• Lipoteichoic acid
• Protein A
• MSCRAMM..microbi
al surface components
recognizing adhesive
matrix molecules
• Mucin
• IgA, glycolipids,
gangliosides
• Surfactant protein A
• Hydrophobic
interactions
• Surface charge
• Bacterial interference:
coag neg staph,
coryneforms, other S
aureus
• Agr, Sar
Host factors
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Ethnicity
Males>females
Young> old
Hormonal status
Carrier epithelial cells
> non-carrier
epithelial cells
• Eczema pt cells >
normals
• Hospital exposure
• Paired
partners/concordance
• DM,ESRD, IVDU,
allergies, liver dis,
HIV, WBC dysf’n,
Wegeners, sinusitis
• Defensins
• Cigarettes (-)
Intranasal mupirocin to prevent post surgical
infection: systematic review. JAC 2008 61; 254
Randomized untreated
controls
Randomized to receive
mupirocin intra nasally
(Double-blind in ¾
studies)
46/686 (6.7%) subjects
25/688 (3.6%) subjects
developed post operative developed post operative
wound infection
wound infection
RR 0.55, 95% CI 0.34-0.89, p <0.02
CHG,mupirocin,Rif/Doxy for
decolonization. Simor et al, CID 2007; 44:178
Randomized to
No. MRSA
Negative at 3
months
112 patients randomized and
followed post decolonization
No Decol Decol
8/25 (32%) 64/87(74%) P
<.0001
Why consider decolonization or suppression?
• “decolonization” = to
change carraige status,
based on cultures
• Decolonization isn’t
eradication
• “suppression” = to
temporarily reduce
skin shedding and
microbial ‘load’
• All of these
manoeuvres to reduce
body carraige are still
experimental.
Variables that affect
carraige are not all
known at present
• Use of these strategies
should be part of an
investigative program
Screen for MRSA Admission screen
colonization
Prevalence screen
Isolate, barrier, cohort
Suppression, arrest
transmission, ?
decolonize
Decolonization clinic
Outpatient referrals
Rationale for decolonization
• Reduce recurrent infection in carriers
• If body is decolonized, where other normal flora is
able to return to various sites, then these persons
will not continue to be a source of organisms to
colonize others
• Decolonization may be too laborious in
hospitalized acute care patients. In this setting, a
more limited objective of load reduction might be
attempted.
• Transmission and reduced case rates, reduced
isolation needs are to be determined.
Components of MRSA decolonization
• Persistent carriage is
documented
• Risk factors for failure:
elderly, wounds, skin
conditions, DM (treat)
• Compliance
• Nasal mupirocin [fucidin,
0.2% CHG] x 7-10 d
• Body baths CHG 4% x 710 days
• Systemic Rx: SxT,
Doxycycline,
Clinda, Rifampin
• Linen changes
• Under/clothes
changes
• House cleaning
quats or bleach
• Household
contacts
Cultures
• Confirm persistent carraige at various sites
• Nares, throat, body Z/axillae,
groin/perirectal/vaginal, hands, lesions
• 1+ to 4+ on agar surface (semi Q, also broth
amplification)
• Screen of household contacts, if positive
include as new subject
• PFGE, molecular testing re virulence
markers
Overall strategy in CHR
• Relatively closed system, AcuteLTC/
community (bi-directional)
• Increase screening to targeted admission screens,
prior point prevalence to cohort patients
• Investigate strategy of microbial load reduction to
determine if this would limit transmission. Can it
allow modification of barrier techniques?
• After discharge, stable  refer to decolonization
clinic to attempt clearance of carraige, as a study
program.
What’s been done so far in CHR?
• Dialogue with
administration to
indicate that rates are
rising despite ‘regular’
infection control
approach
• [prior assessment that
we are failing to
contain rising rates]
• Obtain high level
support / funds to
conduct wider
screening
• Model
screening/search and
suppress approach
(1000 pts)
• Establish clinic for
discharged MRSA pts
to study
decolonization
The clinic…
• Temporary UCMC 6, AGW5, HPTP FMC, two
½ days/ week 0.25 RN/ID staff, needs 1.0 FTE
NP, needs a physician of note.
• 0.5 FTE Secretarial/ Patient scheduler, needs to be
increased to 1.0 FTE
• Cultures: SemiQ at all sites, low count broth
cultures
• Bacterial interference as possible last resort mode
of treatment
• Supplies: CHG scrubs/baths, Nasal Rx, Quats,
Info,
Follow up
• After confirmation of persistent carraige, family
contact cluster, book for start of decolonization
• Treat for 7 days with topicals Nasal / skin if no
lesions, treat with added antimicrobials if lesions.
Arbitrary re duration. 2-3 weeks if deep seated.
• Follow up cultures 1, 4, 12 weeks, if possible 6
months. General concensus re 12 weeks/90 days
as reasonable breakpoint for duration of followup
Results of Decolonization in CHR
• 314 persons referred
for screening
including family
clusters
• 76 different families
• Variable compliance
• Aim for 1 week, 1 mo,
3 mo, 6 mo. F/U
• Uncomplicated, no
ulcers, normal skin ,
mup S = good success
rate ~75%
• If mup R, high
failure/recurrence
• Psoriasis, eczema is
high risk of failure
• caMRSA 10 appears
more difficult to clear,
more recurrences.
Summary of decolonization
• Labour intensive for
patients, esp. cleaning
household/laundry
• Dermatology
consultative care
essential for patients
with skin disorders
• Still do not have a
formula that
guarantees success.
Novel therapies?
Photoactive
destruction of MRSA?
• Need for
susceptibilities
• Need to study ecology
of nose/skin,
adherence factors,
strain differences.
• CHG and nasal
treatments to
suppress/eradicate,
also deplete normal
flora.