Identification of β-lactamases in human and bovine isolates of Staphylococcus aureus strains having borderline resistance to penicillinase-resistant penicillins (PRPs) with proteomic methods.
Methicillin and oxacillin-hydrolyzing enzymes of 6 borderline methicillin-resistant and 1 methicillin-resistant Staphylococcus aureus strains isolated from human clinical samples and 4 borderline methicillin-resistant S. aureus strains isolated from bovine mastitis were investigated. As previous studies suggested the involvement of an additional enzyme besides the penicillinase BlaZ in the determination of borderline resistance, we analyzed the expressed extracellular and membrane-bound β-lactamases with 2-D gel electrophoresis and mass spectrometry. Our analysis showed that the penicillin-hydrolyzing BlaZ alone was responsible for the hydrolysis of both methicillin and oxacillin. All supernatant and membrane fractions contained the same enzyme with slight sequence variations. The size and pI of the proteins were also variable, probably due to spontaneous hydrolysis and/or posttranslational modifications. Interestingly, we found also cytotoxins and other virulence factors in some nitrocefin-hydrolyzing dots, suggesting that those proteins might have a role in the reduction of local antibiotic concentration.
Keseru
Judit Szilvia
JS
Department of Human Genetics, University of Debrecen, Debrecen, Hungary. kevia@freemail.hu
Szabó
István
I
Gál
Zsuzsanna
Z
Massidda
Orietta
O
Mingoia
Marina
M
Kaszanyitzky
Eva
E
Jánosi
Szilárd
S
Hulvely
Julianna
J
Csorba
Attila
A
Buzás
Krisztina
K
Hunyadi-Gulyás
Eva
E
Medzihradszky
Katalin F
KF
Biró
Sándor
S
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002417:Cattle; D002511:Cephalosporins / Q000378:metabolism; D024881:Drug Resistance, Bacterial; D005260:Female; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism; D055624:Methicillin-Resistant Staphylococcus aureus / Q000201:enzymology / Q000302:isolation & purification; D010405:Penicillinase / Q000378:metabolism; D010406:Penicillins / Q000494:pharmacology*; D040901:Proteomics; D013203:Staphylococcal Infections / Q000382:microbiology; D013211:Staphylococcus aureus / Q000187:drug effects / Q000201:enzymology* / Q000302:isolation & purification*; D001618:beta-Lactamases / Q000302:isolation & purification* / Q000378:metabolism*
D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D008565:Membrane Proteins; D010406:Penicillins; D010405:Penicillinase; D001618:beta-Lactamases; C021720:nitrocefin