Resistenze batteriche e
terapia delle infezioni
postoperatorie
 Fausto
de Lalla,Vicenza
Postoperative infection 2006
Despite
the great advances in
surgical technique and
antibiotic prophylaxis, and
ongoing research in this field,
wound infection remains
a considerable cause of
morbidity and mortality
among surgical patients
Antibiotic Resistance
The knowledge of sensitivity patterns
of the most likely etiological agents of
postoperative infections is pivotal for
the success of both
- perioperative prophylaxis, and
- empiric treatment of SSIs
TRADITIONAL CLASSIFICATION
Clean
surgery
Clean-contaminated surgery
Contaminated surgery
Dirty surgery
Pathogens Causing Surgical Site Infections
Are different, in respect to the surgical procedure and
the site of infection.
Infections following:
- CLEAN SURGICAL PROCEDURES
(with or without implantation of vascular grafts or
prosthetic devices)
- SUPERFICIAL,INCISIONAL SSIs (i.e. simple infection
of the surgical incision, involving only skin and
subcutaneous tissue) :
are most often caused by
Staph. aureus or coag. negative staphylococci
(patient’s skin flora, surgical team, exogenous environment)
Pathogens Causing Surgical Site
Infections
Deep and “organ space”
infections following
CLEAN- CONTAMINATED SURGERY :
- are more often polymicrobial infections
- are caused by the normal endogenous
microflora of the structure which has
been transected
Most Likely SSI Pathogens according
to Operation Type
Operation
 Appendectomy
colorectal
 Gastroduodenal




Biliary tract
OB/GYN.
Urologic
Head and neck
negative
Likely pathogens
- gram-negativi bacilli + anaerobes
(B.fragilis)
- gram-negativi bacilli  oropharingeal
anarobes; streptococci
- gram-negativi bacilli±Enterococcus spp
- gram-negativi bacilli + anaerobes (B.
fragilis)± enterococcus spp; streptococc
- gram-negative bacilli
- oropharingeal anarobes ± grambacilli; streptococci;
Eziologia delle infezioni postoperatorie
-Resistenze
-gram positivi
- gram negativi
- microrganismi in situazioni
particolari
Emerging Gram-positive Microorganisms in Postoperative Infections
MR
staphylococci
VR
enterococci
Surgical Infection with Antibiotic-resistant
Microorganisms
Surgical patients with infections by
MR staphylococci or VRE have:
 a significantly higher mortality rate
 longer hospitalization
 longer treatment before the discharge
than patients with infections by MS staphylococci or
glycopeptide sensitive enterococci
Nichols RL, Am J Med 1998;
Gleason et al, Arch Surg 1999;
Mekontso DA, et al. CID 2001; Edmond MB, et al. CID 1996
Significance of Enterococci in
Surgical Infections
 Enterococcal
bacteremia carries a serious
prognosis
 Patients
with intra-abdominal infection and an
initial isolation of enterococci have a
significant higher treatment failure rate *

VRE infections, and particularly VRE bacteremia, are
associated with high morbidity and mortality**
* Burnett RJ, Dellinger EP, et al. Surgery 1995
** Edmond MB, et al. CID 1996
Microbiologia delle peritoniti secondaria(comunitaria) e
postoperatoria (ospedaliera)
microrganismo
comunitaria (%) ospedaliera(%)
-
Enterococchi
E. coli
Enterobacter spp.
Bacteroides spp
Klebsiella spp
S.aureus
S.coagulasi neg.
Streptococcus spp
Pseudomonas spp
-
Roehrborn A. CID 2001;33:1513-9
-
-
5
36
3
10
7
1
1
14
2
21
19
12
7
7
6
5
4
6






p
0,001
0,005
0,05
NS
NS
0,05
0,05
0,005
NS
VRE: isolamenti per materiale
ANNO
2001
2002
MATERIALE
N° ISOLAMENTI
Feci
24
Urine
7
Ferita chir.
3
Sangue
2
Liquor
1
Drenaggio bil.
1
Feci
85
Urine
3
Piaga decubito
Bile
1
1
MR Staphylococci in Surgical Site Infections
(S.Bortolo Hospital)
Dept.
S.aureus
MR/ tot S.aureus (%)
- Neurosurg.
- Cardiosurg.
- Orthoped.
TOTAL
35/39 (89.7)
11/18 (61.1)
32/58 (55.2)
78/115 (67.8)
de Lalla F. J Hosp Infect 2002
Coag. Neg. staph.
MR/ tot. CNS (%)
18/26 (69.2)
11/15 (73.3)
12/18 (66.7)
41/59 (69.5)
MR Staphylococci in Surgical Site
Infections in Italy
 Ancona and Pesaro Hospitals (676 patients) *
- MR S. aureus/total S.aureus = 104/191 (54%)
- MR CNS/total CNS
= 71/138 (51%)
 S.Bortolo Hospital,Vicenza **
- MR S. aureus/total S.aureus = 78/115 (67.8%)
- MR CNS/total CNS = 41/59 (69.5)
 86 orthopedic centers (2,013 isolates from
SSIs following TH or TK arthroplasties) ***
- MR S. aureus/total S.aureus = 212/463 (46%)
- MR CNS/total CNS
= 156/304 (51%)
* Giacometti A et al. J Clin Microbiol 2000; de Lalla et al,J Hosp Infect
2002;*** Mini E et al, J Chemother 2001
Implications of Resistance for
Selection of Antibiotics in Surgery (1)
TREATMENT OF ESTABLISHED
INFECTIONS:
1) SSIs following clean surgery:
- the high frequency of MR staphylococci as
causative agents should be kept in mind,
AND
glycopetides should be administered in
the empiric treatment of the most serious
of these infections (e.g. prosthetic
infections)
-
PERIOPERATIVE PROPHYLAXIS:
- The administration of glycopeptides as
prophylactic agents in clean prosthetic major
surgery is suggested by some Authors (at least
for those cardiovascular and
orthopedic Depts. in which the
prevalence of MR staphylococci is
considerably high)
- prophylactic glycopeptides are
in clinical practice
extensively used
If the proportion of postoperative S.
aureus infection caused by MRSA (in major
vascular
and
orthopedic
surgical
prostheses) were to rise to 20%, we would
probably advise using
vancomycin or
teicoplanin as prophylactic agents in both
of these areas.
Adam P Fraise, J Antimicrob Chemother 1998;
42:287-289
Antibiotic of choice in clean surgery
prophylaxis
Vancomycin may be the agent of choice in certain
clinical circumstances,such as a cluster of
MRSA mediastinitis or incision infection due to
MR coag.neg staphylococci. A threshold has not
been scientifically defined that can support the
decision to use vancomycin. The decision should
involve local considerations.
CDC Guidelines
Clinical consequences and cost of limiting use of
vancomycin for perioperative prophylaxis:example of
coronary artery bypass surgery (CABS) *
-
-
-
-
-to compare clinical results and cost-effectiveness of no
prophylaxis, cefazolin and vancomycin in CABS
-Decision-analytic models
-Vancomycin resulted in 7% fewer surgical infections
and 1% lower all-cause mortality and saved $ 117 per
procedure,compared with cefazolin.
-Cefazolin resulted in substantially fewer infections
and deaths and lower costs than no prophylaxis
-Data on vancomycin’s impact on resistance are needed
to quantify……..the future long term-consequences to
society
* Zanetti,Goldie, Platt, Emerg Infect Dis 2001;820-7
Glycopeptides Are No More Effective than ß-Lactam Agents
for Prevention of Surgical Site Infection after Cardiac
Surgery: a Meta-analysis (Bolon et al,CID 2004)



7 trials published between 1988-2002 on 5,761 subjects
Glycopeptide : vancomycin (4 studies) or teicoplanin (3 trials)
Comparators: cefazolin (3),cefuroxime (1),ceftriaxone (1),fluc+tobra (1)
 Prevalence of MRSA: low (6
 Blinded: No (5 trials), yes (2studies)
trials), high (1 study)
RESULTS : neither agent proved to be superior for prevention
of occurrence of SSI (primary outcome at 30 days !!)
In subanalyses:
- ß-lactams were superior to glycopeptides for prevention of chest
SSIs, and
- glycopetides were superior for prevention of SSIs caused by MR
gram + bacteria.
Implications of Resistance for
Selection of Antibiotics in Surgery (2)

during treatment with 3rd gen cephalosporins
enterococcal superinfection can occurs

the use of 3rd gen ceph.s is an important risk factor for
VRE colonization and infection in surgical patients *

in the hospitals with high rates of VRE, limitation of
3rd gen ceph.s use, with an increase of penicillins -LI
combinations, is followed by a significant decrease in
the VRE infection **

Dahms RA et al, Arch Surg 1998;

** May AK, Shock 2000
Implications of Resistance for Selection of
Antibiotics in Surgery (3)
- The particular role of Enterococcus spp. as an etiological
agent of tertiary peritonitis (hospital acquired peritonitis)
should be kept in mind (use of extended spectrum
penicillins and penicillin- LIs combinations in the
treatment of abdominal and pelvic surgical infections)
- Postoperative infections in patients who have been
hospitalized for a prolonged period prior to surgery,
and/or have received prior antibiotic treatment are more
likely to involve antibiotic resistant Gram negative
bacilli(ESBL producing Klebsiella pneumoniae, E.coli,
C.freundi, E.cloacae, S. marcescens …..).: the possible
administration of carbapenems should be kept in mind