Distribucija fenotipova i gena rezistencije na makrolide i linkozamide kod gram-pozitivnih koka
Distribution of resistance phenotypes and genes to macrolides and lincozamides in gram-positive cocci
Докторанд
Mišić, MilenaМентор
Baskić, DejanЧланови комисије
Kocić, BranislavaRanin, Lazar
Medić, Deana
Метаподаци
Приказ свих података о дисертацијиСажетак
Uvod/cilj U poslednjoj deceniji zabeleženo je povećanje rezistencije Grampozitivnih koka na antibiotike iz grupe makrolida, linkozamida i streptogramina
A/B (MLSa/b). Složeni mehanizmi rezistencije na MLS antibiotike uključuju:
modifikaciju ribozoma, aktivno izbacivanje antibiotika i modifikaciju
antibiotika. Porodica gena odgovornih za kodiranje enzima koji vrše metilaciju
ribozoma je označena skraćenicom erm (od engl. erythromycin resistance methylase) i
dovode do pojave unakrsne rezistencije na makrolide, linkozamide i streptogramine
grupe B (MLSb). Profil rezistencije poznat kao MLSb fenotip može biti:
inducibilan (iMLSb) i konstitutivan (cMLSb). Sojevi sa erm posredovanom
eritromicin rezistencijom mogu se pokazati osetljivim na klindamicin u rutinskom
disk difuzionom testiranju osetljivosti.
Ciljevi Utvrditi učestalost fenotipova i gena rezistencije na MLS antibiotike kod
Gram-pozitivnih koka na području jugoistočne Srbije.
Metode MLS fenotipovi rezistencije: konstitut...ivni (cMLSb), inducibilni (iMLSb),
M/MSb i LSa/b, bili su utvrđeni dupli-disk difuzionom metodom (D-testom).
Ispitano je 2366 kliničkih izolata Gram-pozitivnih koka, sakupljenih u toku
jednogodišnjeg perioda u Centru za mikrobiologiju Zavoda za javno zdravlje Vranje.
Geni koji kodiraju MLSb rezistenciju (ermA, ermB, ermC, msrA, msrB, mefA/E, lnuA,
lnuB, lsaA i lsaC) su identifikovani korišćenjem multipleks PCR-a.
Rezultati Najveću učestalost rezistencije na eritromicin imali su izolati
meticilin-rezistentnih koagulaza-negativnih stafilokoka (MRCNS, 91,5%), zatim
meticilin-rezistentnih S. aureus (MRSA, 86,4%) i enterokoka (80,8%). Niža, ali još
uvek visoka stopa rezistencije na eritromicin je bila prisutna i kod drugih izolata
Gram-pozitivnih koka. Nasuprot makrolidima, izuzev za izolate Enterococcus spp.
(96,7%), Streptococcus pneumoniae (35,9%) i MRSA (28,4%), drugi izolati Grampozitivnih koka su pokazali značajno nižu rezistenciju na klindamicin. Otkrili smo
da je iMLSb fenotip najučestaliji kod stafilokoka, kod enterokoka i bakterija S.
agalactiae i S. pnemoniae bio je dominantan cMLSb fenotip, dok je M/MSb fenotip bio
najčešće prisutan kod bakterija S. pyogenes. Od ukupnog broja izolata četiri soja suV
pokazala novi "keyhole" fenotip. Najčešći pojedinačni geni i njihove kombinacije
detektovane kod stafilokoka su bile msrA/B, ermC i ermS+msrA/B, dok su kod
enterokoka i ß-hemolitičkih streptokoka bile lsaA, ermB i ermB+lsaA.
Zaključak Utvrdili smo visoku stopu rezistencije na eritromicin kod Grampozitivnih koka. Meticilin-rezistentne stafilokoke su bile značajno rezistentnije
na MLS antibiotike u odnosu na meticilin-senzitivne stafilokoke. Najčešće
identifikovani gen MLS rezistencije među stafilokokama bio je ermC, dok je među
enterokokama i ß-hemolitičkim streptokokama bio ermB gen. Utvrđena je jasna razlika
u obrascu MLS osetljivosti među stafilokokama i enterokokama/streptokokama i
potvrđena je neophodnost uvođenja D testa u rutinskom testiranju antimikrobne
osetljivosti kod izolata stafilokoka.
Introduction The increase of resistance to macrolide, lincosamide, and streptogramin a/b
antibiotics (MLSa/b) among Gram-positive cocci has been reported in the last decade. The
complex mechanisms of resistance to MLS antibiotics include: modification of ribosome,
active efflux of antibiotics and antibiotic inactivation. The gene family called erm
(erythromycin resistance methylase) that encoding enzymes responsible for
ribosome methylation leads to cross- resistance to macrolides, lincosamides and streptogramin
b (MLSb resistance phenotype). The antimicrobial resistance profile known as MLSb
resistance phenotype can be either inducible (iMLSb) and constitutive (cMLSb). Macrolide
resistant strains carrying erm gene can show false sensitivity to clindamycin, using routine
antimicrobial susceptibility test.
Objective This study investigated the prevalence of MLS resistance phenotypes and genes in
Gram-positive cocci in region of the Southeast Serbia.
Methods MLS resistance ph...enotypes: constitutive (cMLSb), inducible (iMLSb), M/MSb, and
LSa/b, were determined by the double-disk diffusion method. We have analyzed 2366 clinical
isolates of Gram-positive cocci, collected during 1-year period at the Center for Microbiology
of the Public Health Institute in Vranje, Serbia. The MLS resistance genes (ermA, ermB, ermC,
msrA, msrB, mefA/E, lnuA, lnuB, lsaA, and lsaC) were identified by multiplex PCR.
Results The highest frequencies of isolates resistant to erythromycin were found among
methicillin-resistant coagulase-negative staphylococci (MRCNS, 91.5%), methicillin-resistant
S. aureus (MRSA, 86.4%) and Enterococcus strains (80.8%). Lower, but still high resistance
rate to erythromycin was found among other Gram-positive cocci. Contrary to macrolides,
except for Enterococcus spp. (96.7%), S. pneumoniae (35.9%), and MRSA (28.4%), other
Gram-positive cocci showed significantly lower resistance to clindamycin. We have found that
iMLSb is the most prevalent phenotype in staphylococci, the cMLSb is predominantly in
enterococci, S. agalactiae, and S. pnemoniae, whereas the M/MSb phenotype is the most
frequent in S. pyogenes. LSa/b phenotype was the most common in enterococci and beta
haemolytic streptococci, but nearly or totally absented among staphylococci, S. pneumoniae,
and S. pyogenes. The novel keyhole zone phenomenon was detected in four out of total number
of clinical isolates. The most prevalent MLS resistance genes and their combinations detectedVII
in staphylococci were msrA/B, ermC and ermС+msrA/B, whereas lsaA, ermB и ermB+lsaA
were predominantly found in enterococci and beta haemolytic streptococci.
Conclusion Generally, high rates of erythromycin resistance in Gram-positive cocci was
found. The methicillin-resistant staphylococci were significantly more resistant to MLS
antibiotics than methicillin-sensitive staphylococci. The most frequent MLS resistance gen
among staphylococci isolates was ermC, whereas the ermB gen was the most prevalent in
enterococci and ß-haemolytic streptococci. We have also discovered a clear differences of MLS
resistance pattern in staphylococci and enterococci/streptococci, and confirmed the necessity
of routine D-testing of all clinical isolates of staphylococci.
Факултет:
Универзитет у Крагујевцу, Факултет медицинских наукаДатум одбране:
30-09-2019Пројекти:
- Преклиничка испитивања биоактивних супстанци (RS-MESTD-Integrated and Interdisciplinary Research (IIR or III)-41010)
- Истраживање савремених биотехнолошких поступака у производњи хране за животиње у циљу повећања конкурентности, квалитета и безбедности хране (RS-MESTD-Integrated and Interdisciplinary Research (IIR or III)-46012)
- Синтеза, моделовање, физичко-хемијске и биолошке особине органских једињења и одговарајућих комплекса метала (RS-MESTD-Basic Research (BR or ON)-172016)