Fenotipske i genotipske karakteristike makrolid rezistentnog Streptococcus pneumoniae / Phenotypic and genotypic characterization of macrolide resistant Streptococcus pneumoniae

Description

<p><em>Streptococcus pneumoniae</em> (pneumokok) je&nbsp; jedan&nbsp; od&nbsp; vodećih&nbsp; uzroka morbiditeta i mortaliteta &scaron;irom sveta, kada su u pitanju infektivne bolesti. Pretežno izaziva infekcije gornjih respiratornih puteva (sinuzitis, otitis) i konjunktivitis. Vodeći je uzročnih vanbolničkih pneumonija, bakterijskog meningitisa i sepse. Lekovi izbora u terapiji pneumokoknih bolesti su beta laktamski antibiotici i makrolidi. Iako se makrolidni antibiotici uveliko koriste u lečenju pneumokoknih infekcija &scaron;irom sveta, porast rezistencije na makrolide&nbsp; bi&nbsp; mogao&nbsp; da&nbsp; kompromituje&nbsp; njihovu&nbsp; upotrebu. Rezistencija pneumokoka na makrolide je posredovana putem dva glavna mehanizma: modifikacija ciljnog mesta delovanja leka&nbsp; i aktivni efluks leka. Metilaciju 23S ribozomalne ribonukleinske kiseline (rRNK) obavlja enzim metilaza, čiju sintezu kodira<em> ermB</em> gen. Kod ovog tipa rezistencije dolazi do ukr&scaron;tene rezistencije na makrolide (M), linkozamide (L) i streptogramine B (Sb). Ovakav vid rezistencije se ispoljava kao MLS_b - fenotip i karakteri&scaron;e ga visok nivo rezistencije. Može se javiti kao konstitutivni (cMLS) i inducibilni (iMLS). Drugi mehanizam rezistencije na makrolide je aktivni efluks leka, kodiran od strane <em>mefA</em>&nbsp; gena. Efluks antibiotik a determini&scaron;e rezistenciju samo na 14-člane i 15-člane makrolide, bez ukr&scaron;tene rezistencije. Ispoljava se kao M-fenotip, a karakteri&scaron;e ga niži stepen rezistencije. Cilj ove studije je bio&nbsp; da&nbsp; se&nbsp; odredi u čestalost&nbsp; makrolidne&nbsp; rezistencije <em>Streptococcus pneumoniae</em> među invazivnim i neinvazivnim izolatima kod dece i odraslih, da se odrediti u čestalost korezistencije i multiple rezistencije kod makrolid rezistentnih sojeva&nbsp; <em>Streptococcus pneumoniae</em>, da se fenotipski odredi tip rezistencije na makrolide i da se ispita genska osnova makrolidne rezistencije (detektovati prisustvo <em>ermB</em> i <em>mefA</em> gena). Analizirani su podaci o 326 sojeva <em>Streptococcus pneumoniae</em> rezistentnih na makrolide (MRSP) sakupljenih &scaron;irom&nbsp; Srbije&nbsp; u&nbsp; periodu&nbsp; od&nbsp; januara&nbsp; 2010.&nbsp; do&nbsp; decembra&nbsp; 2012.&nbsp; godine. Sakupljeni&nbsp; MRSP&nbsp; izolati&nbsp; su&nbsp; transportovani&nbsp; u&nbsp; Nacionalnu&nbsp; referentnu laboratoriju za streptokok radi daljih ispitivanja. Identifikacija je vr&scaron;ena na osnovu mikroskopskih, kulturelnih i biohemijskih osobina. Konzervacija je vr&scaron;ena u moždano-srčanom bujonu sa 10% sadržajem glicerola na -80&deg;C. Dvostruki&nbsp; disk&nbsp; difuzioni&nbsp; test,&nbsp; kombinovani&nbsp; difuzion odilucioni&nbsp; test&nbsp; i automatizovani VITEK 2 sistem su kori&scaron;ćeni za određivanje fenotipova rezistencije na makrolide. Geni koji kodiraju rezistenciju na makrolide su detektovani PCR metodom. Ukupna rezistencija sojeva <em>S.pneumoniae</em> na makrolide u Srbiji je iznosila 34%. Sojevi <em>S.pneumoniae</em> rezistentni na makrolide su če&scaron;će bili izolovani kod dece (36%) u odnosu na odrasle (29%) osobe, i če&scaron;će su izolovani iz neinvazivnih (35,5%) u odnosu na invazivne (27,4%) materijale. Dominantan fenotip rezistencije na makrolide je bio MLS_b fenotip (78,5%). Konstitutivan MLS fenotip je bio zastupljen kod 73,9%, a inducibilan MLS kod 4,6% MRSP izolata. Potvrđena je udruženost <em>mefA</em>&nbsp; gena i M fenotipa; <em>ermB</em> gena i iMLS fenotipa, kao i <em>ermB</em> gena i cMLS fenotipa. Prisustvo oba ermB i mefA gena rezistencije je potvrđeno kod 43,9 % izolata. Svi izolati sa koji su imali oba gena rezistencije su ispoljili&nbsp; MLS_b fenotip.&nbsp; Istovremena&nbsp; neosetljivost&nbsp; na&nbsp; penicilin&nbsp; je bila zastupljena kod 16% MRSP sojeva. Visok nivo rezistencije na penicilin je imalo svega 5,8% MRSP izolata. Među MRSP sojevima je bio prisutan visok nivo&nbsp; rezistencije&nbsp; na&nbsp; tetraciklin&nbsp; (81,3%)&nbsp; i&nbsp; trimetoprim-sulfametoksazol (74,3%). Multirezistenti sojevi, koji su bili rezistentni na tetracikline i trimetoprim-sulfametoksazol su predstavljali dve trećine (66,1%) MRSP izolata.&nbsp; Zastupljenost&nbsp; udružene&nbsp; rezistencije&nbsp; MRSP&nbsp; na&nbsp; tetraciklin i trimetoprim-sulfametoksazol je bila veća kod sojeva sa MLS fenotipom (73,1%)&nbsp; u&nbsp; odnosu&nbsp; na&nbsp; sojeve&nbsp; sa&nbsp; M&nbsp; fenotipom&nbsp; (36,7%). Zastupljenost istovremene rezistencije na makrolide i druge antibiotike među kojima su penicilin, amoksicilin, cefotaksim, tetraciklin, trimetoprim-sulfametoksazol, kao&nbsp; i&nbsp; multirezistentnih&nbsp; sojeva&nbsp; je&nbsp; bila&nbsp; veća&nbsp; kod pedijatrijskih&nbsp; izolata pneumokoka&nbsp; u&nbsp; odnosu&nbsp; na&nbsp; sojeve&nbsp; dobijene&nbsp; kod&nbsp; odraslih.&nbsp; U čestalost istovremene rezistencije na makrolide i druge antibiotike među kojima su tetraciklin i ofloksacin je bila vi&scaron;e prisutna među neinvazivnim u odnosu na invazivne MRSP izolate. Invazivni MRSP izolati iz likvora su pokazivali veću rezistenciju na beta laktamske antibiotike u odnosu neinvazivne sojeve. MRSP sojevi su pokazali veoma visok nivo osetljivosti na levofloksacin (99,6), telitromicin (98,4%), cefotaksim (93,5%), i mipenem (97,3%). MRSP sojevi su u potpunosti bili osetljivi na vankomicin, linezolid, moksifloksacin, sparfloksacin, rifampicin&nbsp; i&nbsp; pristinamicin.&nbsp; Među&nbsp; invazivnim&nbsp; sojevima <em>S.pneumoniae</em> rezistentnim na makrolide je nađeno 12 različitih serotipova. Polovina izolata je pripadala serotipovima 19F (25%) i 14 (23%), dok su sledeći po učestalosti bili 6A (10,4%) i 23F (8,3%). Istovremena rezistencija na makrolide, penicilin, tetracikline i trimetoprim-sulfametoksazol je nađena kod serotipova 19F, 14 i 23F, dok su serotpovi 12F i 31 bili neosetljivi samo na makrolide. Na&scaron;e istraživanje predstavlja prvu detaljnu analizu fenotipskih i&nbsp; genotipskih&nbsp; osobina&nbsp; sojeva&nbsp; pneumokoka&nbsp; rezistentnih&nbsp; na&nbsp; makrolidne antibiotike u Srbiji. Dobijeni rezultati ukazuju na&nbsp; potrebu za aktivnim nadzorom nad pneumokoknim infekcijama u Srbiji.</p> / <p><em>Streptococcus pneumoniae</em> (pneumococcus) is one of the leading morbidity and&nbsp; mortality&nbsp; causes&nbsp; all&nbsp; over&nbsp; the&nbsp; world&nbsp; with&nbsp; respect&nbsp; to&nbsp; infectious&nbsp; diseases. <em>Streptococcus&nbsp; pneumoniae</em> is&nbsp; a&nbsp; leading&nbsp; cause&nbsp; of upper&nbsp; respiratory&nbsp; tract infections&nbsp; (&nbsp; sinusitis,&nbsp; otitis)&nbsp; and&nbsp; conjunctivitis. It&nbsp; is&nbsp; also&nbsp; the&nbsp; most&nbsp; common cause&nbsp; of&nbsp; community-acquired&nbsp; pneumonia, bacterial&nbsp; meningitis&nbsp; and&nbsp; sepsis. Beta lactam and&nbsp; macrolide antibiotics remained a first choice for empirical treatment of pneumococcal infections. Although macrolides are widely used for&nbsp;&nbsp; treatment&nbsp;&nbsp; of&nbsp;&nbsp; pneumococcal&nbsp;&nbsp; infections, an&nbsp;&nbsp; increase&nbsp;&nbsp; in&nbsp;&nbsp; macrolide resistance&nbsp; might compromise&nbsp; their use. Pneumococcal&nbsp; macrolide resistance is&nbsp; mediated&nbsp; by&nbsp; two&nbsp; major&nbsp; mechanisms:&nbsp; target&nbsp; site&nbsp; modification&nbsp; and&nbsp; active drug&nbsp; efflux.&nbsp; Methylation&nbsp; of&nbsp; the&nbsp; 23S&nbsp; ribosomal&nbsp; ribonucleic&nbsp; acid&nbsp; (rRNA)&nbsp; is performed&nbsp;&nbsp; by&nbsp;&nbsp; the&nbsp;&nbsp; enzyme&nbsp;&nbsp; methylase,&nbsp;&nbsp; encoded&nbsp;&nbsp; by&nbsp;&nbsp; the<em> ermB </em>gene. Modification&nbsp; of&nbsp; ribosomal&nbsp; targets&nbsp; leads&nbsp; to&nbsp; cross-resistance to&nbsp; macrolides (M),&nbsp; lincosamides&nbsp; (L)&nbsp; and&nbsp; streptogramins&nbsp; B&nbsp; (Sb). It&nbsp; is&nbsp; expressed&nbsp; as&nbsp; the MLS_b &ndash;phenotype,&nbsp; which&nbsp; confers&nbsp; a&nbsp; high-level&nbsp; resistance. This&nbsp; phenotype&nbsp; can&nbsp;&nbsp; be&nbsp;&nbsp; either&nbsp;&nbsp; constitutively&nbsp;&nbsp; (cMLS)&nbsp;&nbsp; or&nbsp;&nbsp; inducibly&nbsp;&nbsp; (iMLS). expressed. Another macrolide resistance mechanism is the active drug efflux, encoded by&nbsp; the <em>mefA&nbsp;</em> gene.&nbsp; The&nbsp; drug&nbsp; efflux&nbsp; confers&nbsp; resistance&nbsp; to&nbsp; 14-&nbsp; and&nbsp; 15-membered&nbsp; macrolides&nbsp; only,&nbsp; with&nbsp; no&nbsp; cross-resistance.&nbsp; It&nbsp; is&nbsp; expressed&nbsp; as&nbsp; the M-phenotype,&nbsp; which&nbsp; confers&nbsp; low-level&nbsp; resistance.&nbsp; The&nbsp; objective of&nbsp; this study&nbsp;&nbsp; was&nbsp;&nbsp; :&nbsp;&nbsp; 1) to&nbsp;&nbsp; examine&nbsp;&nbsp; the&nbsp;&nbsp; prevalence of&nbsp;&nbsp; macrolide&nbsp;&nbsp; resistant <em>Streptococcus&nbsp;&nbsp; pneumoniae </em>(MRSP) among&nbsp;&nbsp; invasive&nbsp;&nbsp; and&nbsp;&nbsp; noninvasive isolates in children and adults, 2) to examine the prevalence of coresistance and multiple-resistance among MRSP strains, 3) to examine the prevalence of&nbsp; macrolide&nbsp; resistant&nbsp; phenotypes,&nbsp; and&nbsp; 4)&nbsp; to&nbsp; examine&nbsp; the&nbsp; prevalence&nbsp; of macrolide&nbsp; resistant&nbsp; genotypes&nbsp; (detect&nbsp; the&nbsp; presence of&nbsp; the <em>ermB</em>&nbsp;&nbsp; and <em>mefA</em> gene).&nbsp; A&nbsp; total&nbsp; of&nbsp;&nbsp; 326&nbsp; MRSP&nbsp; strains&nbsp; were&nbsp; analyzed,&nbsp; which&nbsp; were&nbsp; collecte dall&nbsp; over&nbsp; Serbia&nbsp; in&nbsp; the&nbsp; period&nbsp; from&nbsp; January,&nbsp; 2010&nbsp; - December,&nbsp; 2012.&nbsp; The collected&nbsp;&nbsp; MRSP&nbsp;&nbsp; isolates&nbsp;&nbsp; were&nbsp;&nbsp; referred&nbsp;&nbsp; to&nbsp;&nbsp; the&nbsp;&nbsp; National&nbsp; Reference Laboratory&nbsp; for&nbsp; streptococci&nbsp; and&nbsp; pneumococci for&nbsp; further&nbsp; investigation. Identification based on microscopic, culture and biochemical features of the isolates. Conservation was performed in the brain-heart infusion broth with a&nbsp; 10%&nbsp; glycerol&nbsp; content&nbsp; at&nbsp; -80&deg;C.&nbsp; Macrolide&nbsp; resistance&nbsp; phenotypes&nbsp; were determined by a double disc diffusion test, combine d diffusion-dilution test and&nbsp;&nbsp; automatized&nbsp;&nbsp; VITEK&nbsp; 2 system. Macrolide&nbsp;&nbsp; resistance&nbsp;&nbsp; genes&nbsp;&nbsp; were&nbsp; determined by PCR. Overall, macrolide nonsusceptibility rate in Serbia was 34%.&nbsp; MRSP&nbsp; isolates&nbsp; were&nbsp; more&nbsp; prevale nt&nbsp; among&nbsp; children&nbsp; (36%)&nbsp; than adults&nbsp; (29%),&nbsp; and&nbsp; were&nbsp; more&nbsp; prevalent&nbsp; among&nbsp;&nbsp; noninvasive&nbsp; (35.5%)&nbsp; than invasive&nbsp; (27.4%)&nbsp; samples.&nbsp; Predominant&nbsp; macrolide&nbsp; resistance&nbsp; phenotype was&nbsp; the&nbsp; MLS b&nbsp; phenotype&nbsp; (78.5%),&nbsp; from&nbsp; which&nbsp; 73.9 %&nbsp; belonged&nbsp; to&nbsp; cMLS and&nbsp; 4.6%&nbsp; to&nbsp; iMLS&nbsp; phenotype.&nbsp; All&nbsp; the&nbsp; strains&nbsp; assigne d&nbsp; to&nbsp; the&nbsp; MLS_b phenotype harbored<em> ermB</em> gene, while all the strains with M phenotype had the mefA gene.&nbsp; The&nbsp; presence&nbsp; of&nbsp; both ermB and mefA resistance&nbsp; genes&nbsp; was confirmed&nbsp; in&nbsp; 43.9&nbsp; %&nbsp; of&nbsp; isolates. All&nbsp; the&nbsp; isolates&nbsp; which&nbsp; harbored&nbsp; both resistance genes expressed the MLS_b phenotype. Among macrolide resistant strains,&nbsp; penicillin&nbsp; nonsusceptiblility&nbsp; was&nbsp; observed&nbsp;&nbsp; in&nbsp; 16% .&nbsp; A&nbsp; high&nbsp; level resistance was confirmed in 5. 8% of MRSP isolates. MRSP strains showed high&nbsp; resistance rates to tetracyclin&nbsp; (81.3%) and&nbsp; trimethoprim-sulfamethoxazole&nbsp; (74.3%).&nbsp; Multiresistant&nbsp; strains,&nbsp; resistant&nbsp; to&nbsp; tetracyclines and&nbsp; trimethoprim-sulfamethoxazole,&nbsp; made&nbsp; two&nbsp; thirds&nbsp; (66.1&nbsp; %)&nbsp; of&nbsp; MRSP isolates.&nbsp; Among&nbsp; MRSP,&nbsp; co-resistance&nbsp; to&nbsp; tetracycline&nbsp; and&nbsp; trimethoprim-sulfamethoxazole&nbsp; was&nbsp; more&nbsp; prevalent&nbsp; among&nbsp; MLS&nbsp; phenotypes&nbsp; (73.1%) than&nbsp; M&nbsp; phenotypes&nbsp; (36.7%).&nbsp; Co-resistance&nbsp; strains&nbsp; to&nbsp; macrolides&nbsp; and&nbsp; other antibiotics including&nbsp;&nbsp;&nbsp; penicillin,&nbsp;&nbsp; amoxicillin,&nbsp;&nbsp;&nbsp; cefotaxime,&nbsp; tetracyclin, trimethoprim-sulfamethoxazole and multiresistant&nbsp; strains&nbsp; were more prevalent among children than adult. Coresistance to macrolides and other antibiotics&nbsp; including&nbsp; tetracycline&nbsp; and&nbsp; ofloxacin&nbsp; was&nbsp; more&nbsp; prevalent&nbsp; among noninvasive&nbsp;&nbsp; than&nbsp;&nbsp; invasive&nbsp;&nbsp; strains.&nbsp;&nbsp; Invasive&nbsp;&nbsp; MRSP&nbsp;&nbsp; isolates&nbsp;&nbsp; from&nbsp;&nbsp; the cerebrospinal fluid showed a higher resistance rate to beta lactam antibiotics than&nbsp; noninvasive&nbsp; strains.&nbsp; MRSP&nbsp; strains&nbsp; had&nbsp; a&nbsp; high&nbsp; susceptibility&nbsp; rates&nbsp; to levofloxacin&nbsp;&nbsp; (99.6),&nbsp;&nbsp; telithromycin&nbsp;&nbsp; (98.4%),&nbsp;&nbsp; cefotak sime&nbsp;&nbsp; (93.5%)&nbsp;&nbsp; and imipenem&nbsp; (97.3%).&nbsp; MRSP&nbsp; strains&nbsp; were&nbsp; fully&nbsp; susceptible&nbsp; to&nbsp; vancomycin, linezolid, moxifloxacin, sparfloxacin, rifampicin a nd pristinamycin. Among macrolide&nbsp;&nbsp; resistant <em>S.pneumoniae</em> strains,&nbsp;&nbsp; 12 different&nbsp;&nbsp; serotypes&nbsp;&nbsp; were identified.&nbsp; One&nbsp; half&nbsp; of&nbsp; these&nbsp; isolates&nbsp; belonged&nbsp; to the&nbsp; 19F&nbsp; (27.1%)&nbsp; and&nbsp; 14 (22.&nbsp; 9%)&nbsp; serotype,&nbsp; followed&nbsp; in&nbsp; frequency&nbsp; by&nbsp; the&nbsp; 6A&nbsp; (10.41%)&nbsp; and&nbsp; 23F (8.3%)&nbsp; serotype .&nbsp; Multiresistant&nbsp; strains&nbsp; (macrolides,&nbsp; penicillin,&nbsp; tetracyclines and&nbsp; trimethoprim-sulfamethoxazole)&nbsp; belonged&nbsp; to&nbsp; serotypes 19F,&nbsp; 14&nbsp; and 23F, while the 12F and 31 serotype were resistant to macrolides only. This in vestigation&nbsp;&nbsp; represents&nbsp;&nbsp; the&nbsp;&nbsp; first&nbsp;&nbsp; detailed&nbsp;&nbsp; analysis of&nbsp;&nbsp; phenotypes&nbsp;&nbsp; and genotypes&nbsp; of&nbsp; macrolide&nbsp; resistant&nbsp; pneumococcal&nbsp; strains&nbsp; in&nbsp; Serbia.&nbsp; The obtained&nbsp; results suggest&nbsp; the need for an active surveillance&nbsp; of pneumococcal infections in Serbia.</p>

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Identifer	oai:union.ndltd.org:uns.ac.rs/oai:CRISUNS:(BISIS)94344
Date	24 July 2015
Creators	Hadnađev Mirjana
Contributors	Perin Branislav, Vučković Opavski Nataša, Milošević Vesna, Andrijević Ilija, Mihajlović-Ukropina Mira, Ranin Lazar, Kopitović Ivan
Publisher	Univerzitet u Novom Sadu, Medicinski fakultet u Novom Sadu, University of Novi Sad, Faculty of Medicine at Novi Sad
Source Sets	University of Novi Sad
Language	Serbian
Detected Language	Unknown
Type	PhD thesis