Typization of Klebsiella pneumoniae strains collected from a immature pediatric ward by Mass Spectrometry using MALDI-TOF

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Roberto Degl’Innocenti *
Tamara Brunelli
Daniele Ferri
Lorenzo Pellegrini
Mayra Sosa
Cristiano Chiaramonti
Antonella Conti
(*) Corresponding Author:
Roberto Degl’Innocenti | microbiologia@usl4.toscana.it


Introduction. Klebsiella pneumoniae is often associated with nosocomial infections, especially in immature pediatric wards and intensive care, where the prolonged hospitalization and invasive procedures increase the risk.In this study we investigated the possibility of using MALDI-TOF mass spectrometry for the rapid identification of bacteria and to be able to be used for epidemiological circulation of a particular strain of Klebsiella pneumoniae in a pediatric ward immature at Mercy hospital of Prato and Dolce. Materials and Methods. Twenty Klebsiella pneumoniae strains were isolated and analyzed The isolates were collected from clinical specimens (7 urine, 12 stool samples, 1 skin swab) from 15 patients (9 females and 6 males) of the Department of Pediatrics, Hospital Misericordia and Dolce during the period from May to November 2010. Samples were collected using eSwab containers for urine and swab the skin FecalSwab, for fecal samples, and processed on suitable culture media with theWasp system (Copan Italy Spa distributed by ada Ltd.). Of all isolates were performed identification and susceptibility testing with the automatic Vitek2 (bioMérieux) at the time of isolation, then frozen at -20 °C in Trypticase Soy Broth with 20% Glycerol (Becton Dickinson). Subsequently, the bacterial strains were thawed, subcultured on Columbia Blood Agar with 5% sheep (BioMerieux), typed by means of MALDI-TOF (Shimadzu Axima - Biomerieux) and performed an antibiogram by Kirby-Bauer method (Table 3) on Agar Mueller-Hinton (Liofilchem S.r.l.) and diskettes Bio-Rad. The spectra obtained by MALDI-TOF were analyzed and compared with software-AgnosTec SARAMIS, used in our laboratory, both for the identification of the strains for the construction of a dendrogram. Results.Twenty strains of Klebsiella pneumoniae were studied.They were isolated from clinical specimens (7 urine, 12 stool samples, 1 skin swab) from 15 patients (9 females and 6 males) of the Department of Pediatrics. Of all isolates was performed to identify and sensitivity with automaticVitek2 (bioMérieux) samples from Italian patients and divided stranieri così: 570 endocervical swabs (71.2%), 98 urethral swabs (12.2%), 78 seminal fluids (9.8%), and 54 urine (6.8%).The number of female subjects was higher than those of males [629 (78.5%) vs 172 (21.5%)], the average age of females was 38.4 ± 12.2 years while that of males was 47.7 ± 13.3 years. The prevalence of urogenital pathogens was: 13 T.vaginalis positive (1.6%), 52 for M.hominis (6.5%), 64 for M.genitalium (8.8%), 18 for C.trachomatis (2.2%), 2 for N.gonorrheae (0.2%) and 79 for U.urealyticum (9.9%): of all the 18 positive subjects were positive for more than one pathogen, namely: 1 totaled 4 pathogens, pathogens 5 for 3 and 9 for 2 pathogens. Conclusions.This study provides data on the prevalence of sexually transmitted diseases in the hospital in Prato.


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