Circulation in Italy of beta-lactamase-producing strains within the major groups of bacterial pathogens.

A multicenter study was undertaken in Italy to assess the circulation of beta-lactamase-producing organisms and their current incidence within the major groups of bacterial pathogens. Almost four thousand strains, all freshly isolated from clinical material, were examined at four centers serving different areas of Italy. Despite some significant center-to-center differences, this survey documented the occurrence of a large overall circulation of beta-lactamase-producing organisms among clinical bacterial isolates. In particular, ampicillin resistance was recorded in one third to one half of the isolates of some Enterobacteriaceae, including Escherichia coli, Proteus, and Citrobacter species, and 80-90% of these resistant strains proved to be beta-lactamase producers. Both ampicillin resistance and beta-lactamase production were almost the rule in other Enterobacteriaceae, including Klebsiella, Enterobacter, and Serratia species. beta-lactamase was also produced by about 80% of glucose-non-fermenting gram-negative bacteria and Aeromonas hydrophila strains, by all of the isolates of Branhamella catarrhalis manifesting ampicillin resistance (i.e. more than half the total number of isolates), and by about two thirds of the ampicillin-resistant Haemophilus strains (which accounted for 20-25% of all Haemophilus isolates examined). In contrast, no beta-lactamase producers were observed among Neisseria gonorrhoeae isolates.

Susceptibility in vitro of gram-positive aerobe and anaerobe bacteria to ofloxacin.

Ofloxacin is a new fluoroquinolone derivative active against Gram-positive and Gram-negative bacteria including obligate anaerobes. In this study the in vitro activity of ofloxacin was evaluated against 325 Gram-positive organisms freshly isolated from clinical specimens, in comparison with that of ampicillin, erythromycin, clindamycin and ceftazidime. Susceptibility tests indicated that the MIC90 was 2 mg/l (range 0.25-2) against both methicillin-susceptible (MS) and methicillin-resistant (MR) Staphylococcus aureus. A value of 2 mg/l (range 0.5-4) was also found for all other staphylococci. The MIC of ofloxacin was 8 mg/l for 90% of Streptococcus faecalis (range 1-16), Str. faecium (range 2-8) and members of JK group (range 0.5-16). Propionibacterium acnes strains were all inhibited by 2 mg/l and 90% of Clostridia spp. (range 2-16) by 8 mg/l. Ofloxacin activity compared favourably with that of ampicillin, erythromycin, clindamycin and ceftazidime determined on the same isolates. MBC and time-kill studies indicated that this compound is rapidly bactericidal against enterococci. The great intrinsic activity against MS and MR staphylococci, refractory enterococci and JK bacteria may make ofloxacin a useful adjunct to the therapeutic arsenal.