Serotype distribution and antimicrobial resistance in invasive Streptococcus pneumoniae isolates in Croatia

doctoral thesis

• Title (croatian): Distribucija serotipova i antimikrobna rezistencija u invazivnih izolata Streptococcus pneumoniae u Hrvatskoj
• Author: Iva Butić
• Mentor: Arjana Tambić Andrašević (mentor)
• Committee member: Ana Budimir (predsjednik povjerenstva)
• Committee member: Ivana Mareković (član povjerenstva)
• Committee member: Branka Bedenić (član povjerenstva)
• Granter: University of Zagreb; School of Medicine; Zagreb
• Defense date and country: 2022-06-13, Croatia
• Scientific / art field, discipline and subdiscipline: BIOMEDICINE AND HEALTHCARE; Clinical Medical Sciences; Medical Microbiology
• Universal decimal classification (UDC): 616 - Pathology. Clinical medicine

Abstract

Aims: The general aim was to observe the characteristics (serotypes, antimicrobial resistance) of invasive S. pneumoniae strains depending on the time period and patient age and to determine the extent of coverage by currently available vaccines. Specific aims were to determine the serotype distribution and antimicrobial susceptibility of invasive S. pneumoniae and to determine the resistance mechanisms in macrolide and quinolone-resistant isolates.
------ Materials and methods: Invasive pneumococcal strains were collected through the microbiological laboratories engaged in the national antibiotic resistance surveillance organised as the Croatian Committee for Antibacterial Resistance Surveillance. Capsular typing was performed by the capsular swelling method (the Quellung reaction). In vitro susceptibility testing was performed according to the CLSI and the EUCAST guidelines. The presence of macrolide and fluoroquinolone resistance genes was detected by PCR.
----- Results: The overall incidence of invasive pneumococcal disease (IPD) was 2.92 confirmed cases per 100 000 population. Analysis was done in 1666 out of 1854 consecutively collected, non-copy isolates. A total of 32.6% strains were isolated in children <18 years and 30.9% in adults ≥65 years of age. The most prevalent serotypes among children were 14, 6B, 19A, 23F, 18C and 1, while serotypes 3, 14, 19A, 9V, 23F and 7F were the most prevalent among adults. The trend in the serotype distribution was observed only for serotype 1, which was decreasing. Pneumonia was the most common clinical presentation, in the overall population and among adults. Penicillin non-wild type strains (22%) and macrolide-resistant strains (29.4%), mostly belonged to serotypes 14 and 19A. Resistance to fluoroquinolones was detected in 4 isolates only. The coverage by 10-, 13- and 23-valent vaccines was 69%, 74.5% and 90.6%, respectively, for the target population.
------ Conclusions: The incidence of IPD and serotype distribution varied with patient age. All available vaccines have high coverage for the target population and strains with acquired resistance to the antibiotic.

Abstract (english)

Ciljevi istraživanja: Analizirati karakteristike (serotipovi, antimikrobna rezistencija) invazivnih sojeva Streptococcus pneumoniae, utvrditi eventualne promjene ovisno o vremenskom razdoblju i dobi bolesnika, te opseg pokrivenosti trenutno dostupnim cjepivima. Specifični ciljevi su obuhvaćali distribuciju serotipova i antimikrobnu osjetljivost invazivnih pneumokoka, te mehanizme rezistencije među izolatima rezistentnima na makrolide i kinolone.
----- Materijali i metode: Invazivni sojevi Streptococcus pneumoniae su prikupljeni unutar mreže mikrobioloških laboratorija u sklopu Odbora za praćenje rezistencija bakterija na antibiotike u Hrvatskoj. Serotipizacija je učinjena metodom bubrenja kapsule (the Quellung reaction). Ispitivanje in vitro osjetljivosti na antibiotike je provedeno u skladu s američkim (CLSI) i europskim (EUCAST) laboratorijskim standardima. Metodom reakcije lančane polimeraze je ispitivana prisutnost gena rezistencije na makrolide i fluorokinolone.
----- Rezultati: Ukupna incidencija invazivne pneumokokne bolesti (IPB) je 2.92 dokazanih infekcija na 100 000 stanovnika. Analizom je obuhvaćeno 1666 od ukupno 1854 uzastopno prikupljenih izolata. Među pacijentima s dokazanom IPB 32.6% su bili djeca <18 godina i 30.9% odrasli ≥65 godina. Najčešće zastupljeni serotipovi među djecom su 14, 6B, 19A, 23F, 18C i 1, a među odraslima 3, 14, 19A, 9V, 23F i 7F. Promjena u distribuciji serotipova u promatranom razdoblju uočena je samo za serotip 1 koji je pokazao silazni trend. Pneumonija je bila najčešća klinička prezentacija u cijeloj populaciji i među odraslima. Pneumokoki smanjene osjetljivost na penicilin (22%) i rezistentni na makrolide (29.4%), većinom su pripadali serotipovima 14 i 19A. Rezistencija na fluorokinolone je dokaza u samo četiri izolata. Pokrivenost 10-, 13- i 23-valentnim cjepivima je iznosila 69%, 74.5% i 90.6% za ciljne dobne skupine.
----- Zaključci: Incidencija IPB i distribucija serotipova ovisi o dobi bolesnika. Sva dostupna cjepiva imaju visoku pokrivenost za ciljnu populaciju u Hrvatskoj i sojeve sa stečenom rezistancijom na antibiotike.

• Keywords: Serogroup; Anti-Bacterial Agents; Croatia; Drug Resistance; Bacterial; Pneumococcal Infections; Vaccines
• Keywords (croatian): Serogrupa; Antibakterijska sredstva; Hrvatska; Otpornost na lijekove; bakterija; Pneumokokne infekcije; Cjepiva
• Language: english
• URN:NBN: urn:nbn:hr:105:505808
• Study programme: Title: Biomedicine and Health Sciences; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti, područje biomedicine i zdravstvo (doktor/doktorica znanosti, područje biomedicine i zdravstvo)
• Type of resource: Text
• Extent: 80 str.
• File origin: Born digital
• Access conditions: Open access
• Public note: Sumentor: Waleria Hryniewicz
• Created on: 2022-09-19 10:48:46