THE SPREAD OF NEOMYCIN-RESISTANT STAPHYLOCOCCI IN A HOSPITAL

Antimicrobial resistance of Staphylococcus aureus: genetic basis

Images

Systemic metronidazole combined with either topical povidone-iodine or ampicillin in acute appendicitis

One-hundred consecutive patients undergoing appendicectomy either electively or for clinically diagnosed acute appendicitis were studied to examine the difference between the use of topical povidone-iodine (PVP-I) and ampicillin in the wound given at the time of closure. All patients were treated with metronidazole suppositories for 48 h starting at the time of pre-medication in addition to a topical agent. The overall wound infection rate was 14%. If the appendix was histologically normal or inflamed, the rate fell to 10% whereas if gangrenous or perforated it rose to 24%. Sixty-six per cent of the patients with a perforated appendicitis developed a wound infection. There was no significant difference in the wound infection rate between those treated with PVP-I and those with ampicillin. Topical antisepsis using PVP-I is preferable to ampicillin as it abolishes the risk of antibiotic resistance or allergy developing and since it is comparatively more cost-effective.

Stability of aminoglycoside resistance in vitro in gentamicin-resistant Staphylococcus aureus

Stability of aminoglycoside resistance has been investigated in 20 strains of Staphylococcus aureus resistant to gentamicin (16 strains were also resistant to methicillin). In view of previous reports that incubation at elevated temperatures can hasten the loss of unstable antibiotic resistance, we passaged strains daily in a liquid medium for 24 days at 43 degrees C. The nine strains which were resistant to neomycin kept their aminoglycoside resistance virtually intact, whereas most of the other 11 strains (sensitive to neomycin) lost almost all their resistance to gentamicin and kanamycin after 5 days. It thus appears that the stability of aminoglycoside resistances in Staph. aureus is closely linked to the resistance of the strains to neomycin. This finding has important possible consequences in terms of the advisability of the clinical usage of preparations containing neomycin or framycetin for topical application and bowel sterilization.

Genetic basis, epidemiology, and future significance of antibiotic resistance in Staphylococcus aureus: a review

Images

Binding of neomycin and analogues by fatty acids in vitro

Neomycin forms insoluble complexes with long-chain fatty acids in vitro. This reduces the diffusion of neomycin but does not directly neutralize its antibiotic activity. Possible effects in vivo are discussed.

Cultural characters of a newly recognized group of hospital staphylococci

Members of a newly recognized group of hospital staphylococci, which are believed to have arisen from 83A staphylococci by lysogenization, differ from them in several cultural characters. Some but not all of these characters appear to be determined by the carriage of phage.