Американский Научный Журнал EVELUATION OF PREOPERATIVE NASOPHARYNGEAL COLONISATION OF STAPHYLOCOCCUS AUREUS IN ORTHOPAEDIC IMPLANT SURGERY

Abstract. Staphylococcus aureus (S. aureus) is an independent risk factor for orthopaedic surgical site infection (SSI). There is a strong epidemiologic association between nasopharyngeal carriage of S. aureus and development of S. aureus SSIs. Carriers are two to nine times more likely to acquire S. aureus SSIs than noncarriers . Staphylococcus colonizing nasal or pharyngeal sites can become virulent and cause severe infections. In this study, We retrospectively studed both pharyngeal and nasal colonisation of St.aureus in 59 outpatients who visited TSMU the first university clinic traumatology department for screening purposes before orthopedic implant surgery. One swab was taken from the nostrils which was rotated gently in both nostrils, and one swab was taken from the pharynx by sweeping both tonsils. Specimens were inoculated onto manitol-salt and 5% sheep blood agar palate, which were incubated for 20 to 28 hours at 35°C to 37°C. After 24 hours negative plates were incubated for an additional 24 hours. The absolute S. aureus carriage was 25.42%, as 15 out of the 59 patients had S. aureus in the nose. 2 patients had SA both in the throat and nose. 1 patient had Candida albicans in the throat swab. Screening does not yielded positive nasal cultures MRSA . Thus, the nasal carrier rate was marginally significantly higher than that in the pharynx. We also eveluated antibiotic susceptibility test results which showed resistance to erythromycin, tetracycline,clindamycin and clarithromycine. Скачать в формате PDF
4 American Sci entific Journal № ( 28) / 20 19
ИММУНОЛОГИЯ И МИКРОБ ИОЛОГИЯ

EVELUATION OF PREOPERATIVE NASOPHARYNGEAL COLONISATION OF
STAPHYLOCOCCUS AUREU S IN ORTHOPAEDIC IMPLANT SURGERY

Tamar Didbari dze1, George Obgaidze 2, Inga gvasalia 3 ,Nino Gogokhia 4
1.TSMU Microbiology Department, associate profe ssor,MD,PhD(Tbilisi,Georgia)
2.Head of Traumatology Department,TSMU The First University Clinic,MD,PhD(Tbilisi,Georgia)
3.TSMU The First University Clinic , Physician of infectious diseases,MD,PhD(Tbilisi,Georgia)
4.Head of Laboratory at TSMU The First Univ ersity Clinic,TSMU Laboratory Medicine Department, Full
professor,MD,PhD(Tbilisi,Georgia)

Abstract . Staphylococcus aureus (S. aureus) is an independent r isk factor for orthopaedic surgical site
infection (SSI). There is a strong epidemiologic association b etween nasopharyngeal carriage of S. aureus and
development of S. aureus SSIs. Carriers are two to nine times more likely to acquire S. aureus SSIs than noncarriers
. Staphylococc us colonizing nasal or pharyngeal sites can become virulent and cause severe infections. In this
study, We retrospectively studed both pharyngeal and nasal colonisation of St.aureus in 59 outpatients who visited
TSMU the first uni versity clinic traumat ology department for screening purposes before orthopedic implant
surgery. One sw ab was taken from the nostrils which was rotated gently in both nostrils, and one swab was taken
from the pharynx by sweeping both tonsils. Specimens wer e inoculated onto man itol -salt and 5% sheep blood agar
palate, which were incubated for 20 to 28 hours at 35°C to 37°C. After 24 hours negative plates were incubated
for an additional 24 hours. The absolute S. aureus carriage was 25.42%, as 15 out of the 5 9 patients had S. a ureus
in the nose. 2 patients had SA both in the throat and nose. 1 patient had Cand ida albicans in the throat swab.
Screening does not yielded positive nasal cultures MRSA . Thus, the nasal carrier rate was marginally significantly
high er than that in t he pharynx. We also eveluated antibiotic susceptibility test results which showed resi stance to
erythromycin, tetracycline,clindamycin and clarithromycine.
Keywords: Staphylococcus aureus, antibiotics, screening, imp lant, surgery.

Introd uction:
Staphylococcus aureus is among the most
common causes of surgical site infection (SSI) in
orthop aedic patients ( 1). The association between
Staphylococcus aureus (SA) nasal colonization and
infection was first reported in 1931 ( 2). Since then, it
has been well established that development of SSI
involving SA is associated with preoperative nasal
colo nization with the organism ( 2,3,4 ). Nasal
colonization with SA was the most powerful
independent risk factor for SSI after cardiothoracic
surgery ( 5), a nd in another study of patients undergoing
orthopaedic surgery with prosthetic im plants, nasal
colonizat ion with SA was the most important
independent risk factor for development of a SSI.
Carriers of SA were nine times more likely to have an
SSI develop v ersus noncarriers (95% confidence
interval, 1.7 –45.5) ( 6). The Centers for Diseas e Control
and Preventio n (CDC) describes preoperative nasal
colonization with SA as a risk factor for SSI ( 7).
Methicillin -resistant Staphylococcus
aureus (MRSA) in the commu nity is believed to add to
the burden of SA colonization, and its prevalence is
increasing (8). Furtherm ore, Ellis et al. reported a 3.1 -
fold risk (95% confidence interval, 1.5 –6.5) for
acquiring MRSA infection in MRSA carriers compared
with noncarriers (9 ). It is unknown how these data can
be applied to a preoperative orthopaedic surg ery
population and whet her MRSA colonization status
should play a role in perioperative antibiotic selection
and empiric treatment regimens(10 -
11 ). Staphylococcus aureus is th e most important cause
of orthopaedic infection worldwide. Despite the known
asso ciation between preoper ative colonization with SA
and SSI, little is known about the epidemiology of the
nasal carriage in an orthopaedic surgery
population(12). Nasal coloniz ation can cause
opportunistic and sometimes life -threatening infections
such as s urgical site infections or other infections in
non -surgical patients that increase morbidity, mortality
as well as healthcare costs(13). Up to 30% of the human
population are asymptomatically and permanently
colonized with nasal Staphylococcus aureus . To
successfully colonize hu man nares, S. aureus needs to
establish solid interactions with human nasal epithelial
cells and overcome host defense mechanisms(14).
The aim of our s tudy was to determine the
prevalence of asymptomatic nasopharyngeal
colonization with SA, including MRSA , among healthy
preoperative orthopaedic implant surgery outpatients at
TSMU the First University clinic.
Material and Methods: We performed a
retrospe ctive study of 59 outpatients who visited
TSMU the first university clinic traumatology
department in 20 19 for screening purposes two to
4 weeks before orthopaedic implant surgery. The
presence of MSSA and MRSA, was determined by
microbiological analysis o f nasopharyngeal exudate
and antimicrobial susceptibility was determined. We
collected both pharyngeal a nd nasal exudates . One
swab was taken from the nostrils which was rotated
gently in both nostrils, and one swab was taken from
the pharynx by sweeping bo th tonsils. The protocol
consisted of preoperative screening for S. aureus nasal
carriage and, in carr iers, preoperative use of intranasal
mupirocin with chlorhexidine body wash. Specimens
were inoculated onto manitol -salt and 5% sheep blood
agar palate, which were incubated for 20 to 28 hours at
35°C to 37°C. After 24 hours negative plates were
incubated for an additional 24 hours. The colonies
present on either medium at 48 hours were verified as
S. aureus by Gram’s stai n and coagulase testing

American Scientific Journal № ( 28) / 20 19 5

(Pastorex staph, BioRad). Approximately a week
before surgery, patients with nasal cultures positive for
MSSA or MRSA were educated about the rationale for
the decolonization protocol, which was initiated in the
outpatient setting. We plated both swabs directly on
selective media for SA select medium(Bio -Rad)) and
MRSA (ChromID MRSA; Bio -Rad)). Antibiotic
susceptibil ity testing was performed according to the
European Committee on Antimicrobial
SusceptibilityTesting guidelines release d in 2019 ,
using the Kirby -Bauer disk -diffusion method. From
isolated colonies on selective medium for SA
(ChromID S.aureus, Bio -Rad) an d MRSA (ChromID
MRSA, Bio -Rad). The inoculum 0.5 MacFarland was
streaked into Muller Hinton agar plates (Bi0 -Rad). We
placed the antibiotic disks (Bio -Rad, France) . The
plates were then incubated at 37°C for 18 h and the
following day the inhibition zone diameters were
measured using an electronic caliper for maximum
precision of the measurement. For the quality control of
the Muller Hinton agar plates a nd antibiotic disks, we
used the Kirby -Bauer method with the Culti -Loops SA
control strains ATCC 25923 ( Thermo Fisher Scientific)
Results: The absolute S. aureus carriage was
25.42%, as 15 out of the 59 patients had S. au reus in the
nose. 2 patients had SA both in the throat and nose. 1
patient had Candida albicans in the throat swab.
Screening does not yiel ded positive nasal cultures
MRSA . Thus, the nasal carrier rate was marginally
significantly higher than that in t he pharynx. We also
eveluated antibiot ic susceptibility test results which
showed resistance to erythromycin,
tetracycline,clindamycin and cla rithromycine.
Conclusion: The overall prevalence of S.aureus
nasal carriage varies different countries is repo rted 30%
.Our data is close to the studie s(25,42%). Being a
carrier is an independent risk factor for orthopaedic
surgical site infection (SSI) . We therefore
hypothesized use of a decolonization protocol would
lower the SSI. The antibiotic resistance pa ttern of SA
strains demonstrated a high res istance of St.aureus
probably driven by antibiotic use. Resistance to
erythromycin, tetracycline, clinda mycin and
clarithromycin was high and consequently, these drugs
are not recommended for the empirical therap y of S.
aureus infections. S. aureus is a pathogen with
constantly changing trends in resistance and
epidemiology, and thus requires constant
bacter iological monitoring in healthcare facilities.

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