Naslov
Virulence of Escherichia coli uropathogenic strains producing extended-spectrum β -lactamases isolated in children

Autori
Bedenic, Branka ; Vranes, Jasmina ; Tonkic, Marija ; Natasa, Beader

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
The Book of abstracts of the 5th World Congress of the World Society for Pediatric Infectious Diseases - WSPID / - , 2007

Skup
5th World Congress of the World Society for Pediatric Infectious Diseases - WSPID

Mjesto i datum
Bangkok, Tajland, 15.11.2007. - 18.11.2007

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Escherichia coli; antibiotic; resistance; urinary tract infections; children

Sažetak
Background and aims: The bacteria producing extended-spectrum beta-lactamases (ESBL) have been increasingly reported in pediatric population, neonatal intensive care units in particular. The aim of the study was to investigate virulence factors of the uropathogenic ESBL-producing Escherichia coli strains in children, and to determine the possible differences in the characteristics of ESBL strains isolated in neonates and infants. Material and methods: From January 2002 until December 2003, fifty ESBL- producing E. coli strains were isolated in neonate and infant urine samples collected at Departments of Neonatology and of Pediatrics, Split University Hospital. Antibiotic susceptibilities were determined by broth microdilution method according to CLSI. ESBL production was determined by double-disk synergy test and confirmed by at least threefold reduction in ceftazidime minimal inhibitory concentration (MIC) by clavulanate. The presence of blaTEM, blaSHV and blaCTX-M genes was determined by polymerase chain reaction (PCR). Plasmids were digested with EcoRI, and plasmid fingerprinting patterns were compared by using GelCompare Program. Susceptibility to bactericidal serum activity was tested by Shiller and Hatch method, while adhesin expression was determined by the method of hemagglutination and hemagglutination inhibition in microtiter plates. Results. During the two-year study period, 20 (40%) and 30 (60%) of 50 ESBL- producing E. coli strains were isolated in neonates and infants, respectively. Adhesins were detected in 24 (48%) strains (5 in neonate and 19 in infant group), and difference in adhesin expression between the two groups was statistically significant (p=0.01). P-fimbriae were detected in only 7 strains, six of them in infant urine samples. Hemolysin was produced by 42 (84%) strains (19 in neonate and 23 in infant group), whereas 37 (74%) strains were resistant to serum bactericidal activity (16 in neonate and 21 in infant group) ; the difference was not statistically significant (p>0.05). All isolates were resistant to amoxicillin, 98% to cefazoline, 94% to gentamicin, 87% to cefuroxime and ceftazidime, 77% to netilmicin, 57% to ceftriaxone, 38% to cefepime, 23% to ceftibuten, 21% to cefotaxime, and 11% to co-amoxiclav. Resistance to carbapenems and ciprofloxacin was not observed. There was no statistically significant difference in bla gene detection between the neonate and infant groups (p>0.05). Forty-one strains were tested by PCR for the presence of blaTEM, blaSHV and blaCTX-M genes. The blaTEM gene was detected in five and blaSHV gene in 10 neonatal strains, and blaTEM gene was detected in 10 and blaSHV gene in 14 infant strains tested (p>0.05). The blaCTX-M gene was identified in only four strains. There was a statistically significant difference in adhesin expression between the strains with TEM and SHV  -lactamases because adhesins were detected in 14 of 16 blaTEM strains and only in 10 of 24 blaSHV strains (p=0.01). BlaESBL genes were encoded on related plasmids which contained resistance genes for tetracyclines and aminoglycosides in most cases. Conclusions. The ESBL strains isolated in neonates and infants predominantly produced hemolysin and were resistant to serum bactericidal activity, however, adhesin expression was detected in less than 50% of the strains and was especially rare in the strains isolated from neonatal urine samples. The association between the detection of blaTEM gene and expression of adhesins needs additional studies. Hospital hygiene measures should be employed and the consumption of expanded-spectrum cephalosporins in the Split University Hospital should be restricted in order to reduce the spread of ESBL producing E. coli isolates throughout paediatric units. Since plasmids encoding ESBLs also contain resistance genes for aminoglycosides it is possible that consumption of these antibiotics could also exert the selection pressure which favours the spread of plasmids with ESBL genes.

Izvorni jezik
Engleski

Znanstvena područja
Temeljne medicinske znanosti, Kliničke medicinske znanosti

POVEZANOST RADA