Thesis etd-03312023-171554 |
Link copiato negli appunti
Thesis type
Tesi di laurea magistrale
Author
MAUCERI, ROBERTA
email address
r.mauceri1@studenti.unipi.it, robertamauceri94@gmail.com
URN
etd-03312023-171554
Thesis title
Batteri produttori di β-lattamasi ad ampio spettro in latte ovino massale
Department
SCIENZE AGRARIE, ALIMENTARI E AGRO-AMBIENTALI
Course of study
BIOSICUREZZA E QUALITÀ DEGLI ALIMENTI
Supervisors
relatore Prof.ssa Turchi, Barbara
Keywords
- antibiotico resistenza
- antimicrobial resistance
- ESBL
- ESBL
- escherichia coli
- escherichia coli
- stenotrophomonas malthophilia
- stenotrophomonas malthophilia
- β-lactamase
- β-lattamasi
Graduation session start date
17/04/2023
Availability
Withheld
Release date
17/04/2093
Summary
L'utilizzo di antibiotici β-lattamici nell'allevamento da latte ha portato alla comparsa di batteri resistenti, soprattutto Gram-negativi, grazie alla produzione di enzimi specifici come β-lattamasi a spettro esteso (ESBL). Ciò rappresenta un problema di salute pubblica a causa del potenziale rischio di trasferimento orizzontale dei geni codificanti questi enzimi, attraverso elementi genetici mobili, nei prodotti di origine animale come il latte. Sebbene siano molti gli studi sulla presenza di germi produttori di ESBL nel latte bovino, sono minori le informazioni riguardanti il latte ovino. Per tale motivo, l'obiettivo di questo studio è stato quello di verificare la presenza di batteri produttori di ESBL in campioni di latte ovino provenienti da due regioni del centro Italia e valutarne alcune caratteristiche quali antibiotico resistenza e patogenicità. Il 66% (64/ 97) dei campioni di latte analizzati è risultato positivo per la presenza di microrganismi in grado di sviluppare su terreno ESBL medium. Di questi, solo il 3% (2/64) era presumibilmente riconducibile a E. coli per il tipico colore rosso magenta delle colonie, mentre il 97% (62/64) era ascrivibile a Pseudomonas spp, Acinetobacter spp. o altri batteri Gram-negativi non fermentanti. Successivamente, il sequenziamento del gene 16S rRNA, effettuato su un gruppo di isolati selezionati (n=25) e affiancato a prove biochimiche, ha permesso di rilevare la presenza di Strenotrophomonas malthophilia (20%) e Stenotrophomonas pavanii (16%), seguiti da Pseudomonas aeruginosa (20%) e altre specie di Pseudomonas di minor interesse (16%), E. coli e Proteus terrae (8% entrambi), Achromobacter mucicolens e Achromobacter xylosoxidans (4% entrambi), e infine Hafnia paralvei (4%). I risultati dell'antibiogramma hanno evidenziato una spiccata resistenza nei confronti dei β-lattamici da parte di alcune specie di interesse clinico quali E. coli e S. malthophilia. Soltanto la specie S. malthophilia ha mostrato resistenza nei confronti dei carbapenemi, mentre nel caso di Pseudomonas spp. l'unica resistenza riscontrata è stata quella nei confronti di sulfametossazolo/trimetoprim. In seguito, le PCR condotte sugli isolati di E. coli, risultati essere commensali, non hanno evidenziato la presenza di geni codificanti enzimi ESBL. Solo nel caso di S. malthophilia è stato possibile rilevare geni codificanti β-lattamasi a spettro esteso come L1 e L2.
The use of β-lactam antibiotics in dairy farming has led to the emergence of resistant bacteria, especially Gram-negative ones; Thanks to the production of specific enzymes such as extended spectrum β-lactamases (ESBL). This represents a public health concern due to the potential risk of horizontal transfer of the genes encoding these enzymes, via mobile genetic elements, in products of animal origin such as milk. Although there are many studies on the presence of ESBL-producing germs in bovine milk, there is less information on sheep's milk. For this reason, the aim of this study was to verify the presence of ESBL-producing bacteria in sheep milk samples from two regions of central Italy and to evaluate some characteristics such as antibiotic resistance and pathogenicity. Sixty-six percent (64/97) of milk samples tested were positive for the presence of microrganisms able to growth on ESBL medium. Of these, only 3% (2/64) was presumably attributable to E. coli due to the typical magenta red colour of the colonies, while 97% (62/64) was attributable to Pseudomonas spp, Acinetobacter spp. and other non-fermenting Gram-negative bacteria. Subsequently, the sequencing of the 16S rRNA gene, carried out on a group of selected isolates, (n=25) with others biochemical tests, allowed us to detect the presence of Stenotrophomonas malthophilia (20%) and Stenotrophomonas pavanii (16%), followed by Pseudomonas aeruginosa (20%) and others Pseudomonas species of minor interest (16%), E. coli and Proteus terrae (8% both), Achromobacter mucicolens and Achromobacter xylosoxidans (4% both), and finally Hafnia paralvei (4%). The results of antibiogram test showed a marked resistance against β-lactams in some species of clinical interest such as E. coli and S. malthophilia. Only S. malthophilia showed resistance against carbapenems, while in the case of Pseudomonas spp. the only resistance found was against sulfamethoxazole/trimethoprim. Subsequently, PCR carried out on E. coli isolates, which were commensal, did not show the presence of genes encoding ESBL enzymes. Only in the case of S. malthophilia it was possible to detect genes encoding extended-spectrum β-lactamases such as L1 and L2.
The use of β-lactam antibiotics in dairy farming has led to the emergence of resistant bacteria, especially Gram-negative ones; Thanks to the production of specific enzymes such as extended spectrum β-lactamases (ESBL). This represents a public health concern due to the potential risk of horizontal transfer of the genes encoding these enzymes, via mobile genetic elements, in products of animal origin such as milk. Although there are many studies on the presence of ESBL-producing germs in bovine milk, there is less information on sheep's milk. For this reason, the aim of this study was to verify the presence of ESBL-producing bacteria in sheep milk samples from two regions of central Italy and to evaluate some characteristics such as antibiotic resistance and pathogenicity. Sixty-six percent (64/97) of milk samples tested were positive for the presence of microrganisms able to growth on ESBL medium. Of these, only 3% (2/64) was presumably attributable to E. coli due to the typical magenta red colour of the colonies, while 97% (62/64) was attributable to Pseudomonas spp, Acinetobacter spp. and other non-fermenting Gram-negative bacteria. Subsequently, the sequencing of the 16S rRNA gene, carried out on a group of selected isolates, (n=25) with others biochemical tests, allowed us to detect the presence of Stenotrophomonas malthophilia (20%) and Stenotrophomonas pavanii (16%), followed by Pseudomonas aeruginosa (20%) and others Pseudomonas species of minor interest (16%), E. coli and Proteus terrae (8% both), Achromobacter mucicolens and Achromobacter xylosoxidans (4% both), and finally Hafnia paralvei (4%). The results of antibiogram test showed a marked resistance against β-lactams in some species of clinical interest such as E. coli and S. malthophilia. Only S. malthophilia showed resistance against carbapenems, while in the case of Pseudomonas spp. the only resistance found was against sulfamethoxazole/trimethoprim. Subsequently, PCR carried out on E. coli isolates, which were commensal, did not show the presence of genes encoding ESBL enzymes. Only in the case of S. malthophilia it was possible to detect genes encoding extended-spectrum β-lactamases such as L1 and L2.
File
Nome file | Dimensione |
---|---|
Thesis not available for consultation. |