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Occurrence of various types of penicillinase plasmid among 'hospital' staphylococci
Abstract:
The type of penicillinase plasmid carried by penicillin-resistant cultures of Staphylococcus aureus isolated from eight London hospitals has been determined. Among ;endemic' hospital staphylococci, cultures resistant to mercury salts and producing large amounts of A-type penicillinase, a high proportion of which is extracellular, are most common. C-type penicillinase is rarely associated with resistance to mercury salts.The majority of strains resistant to penicillin and at least one other antibiotic carried the alpha-plasmid. Possible reasons for the prevalence of the alpha-plasmid among endemic hospital staphylococci are discussed.
Insights
Penicillin-resistant Staphylococcus aureus strains in London hospitals commonly carry the alpha-plasmid, often associated with mercury resistance and A-type penicillinase production. This prevalence suggests the alpha-plasmid is significant in endemic hospital settings.
Area of Science:
- Microbiology
- Molecular Biology
- Epidemiology
Background:
- Penicillin resistance in Staphylococcus aureus is a significant healthcare concern.
- Hospital-acquired infections are often linked to antibiotic-resistant bacteria.
- Understanding the genetic basis of resistance, particularly plasmid-borne resistance, is crucial.
Purpose of the Study:
- To determine the types of penicillinase plasmids in penicillin-resistant Staphylococcus aureus from London hospitals.
- To investigate the association between specific plasmid types, antibiotic resistance profiles, and penicillinase activity.
- To explore the prevalence of different penicillinase types (A-type and C-type) and their correlation with other resistance markers.
Main Methods:
- Isolation and characterization of Staphylococcus aureus cultures from eight London hospitals.
- Determination of penicillinase plasmid types.
- Assessment of antibiotic resistance patterns, including resistance to mercury salts.
- Quantification and localization (extracellular vs. intracellular) of penicillinase production.
Main Results:
- A high proportion of endemic hospital staphylococci resistant to mercury salts produced large amounts of extracellular A-type penicillinase.
- C-type penicillinase was rarely associated with mercury salt resistance.
- The majority of strains resistant to penicillin and at least one other antibiotic carried the alpha-plasmid.
Conclusions:
- The alpha-plasmid appears to be prevalent among endemic hospital staphylococci, often linked to multi-drug resistance.
- The association of A-type penicillinase and mercury resistance with the alpha-plasmid suggests a common genetic element driving resistance in these strains.
- Further investigation into the reasons for the alpha-plasmid's prevalence is warranted to inform infection control strategies.