Susceptibility of enterococci to trimethoprim and trimethoprim-sulfamethoxazole.

The in vitro activities of trimethoprim (TMP), alone and in combination with sulfamethoxazole (SMX), against 131 clinical isolates of enterococci, 126 Streptococcus faecalis isolates, and 5 Streptococcus faecium isolates were determined by a broth microdilution method with Mueller-Hinton broth that was substantially free of inhibitory substances. The geometric mean MIC of TMP for strains of S. faecalis was 0.164 micrograms/ml (range, 0.03 to 8 micrograms/ml), with a geometric mean MBC of 0.298 micrograms/ml (range, 0.063 to 8 micrograms/ml). Although all strains were resistant to the sulfonamide alone, the inhibitory and bactericidal activities of TMP against strains of S. faecalis were markedly potentiated when TMP was combined in a fixed ratio of 1:19 with SMX; the geometric mean MIC of TMP was reduced to 0.016 micrograms/ml (range, 0.002 to 0.25 micrograms/ml), with a geometric mean MBC of 0.031 micrograms/ml (range, 0.004 to 0.25 micrograms/ml). The combination had no synergistic effect against strains of S. faecium; the geometric mean MICs and MBCs of both agents were ca. 0.06 micrograms/ml. The MBC/MIC ratios for TMP and TMP-SMX were less than or equal to 16 for all 131 strains. MICs and MBCs for TMP-SMX were unchanged, and for TMP they decreased when performed in broth supplemented with 50% heat-inactivated pooled human serum. For TMP and TMP-SMX, the susceptibilities of isolates with high-level resistance to gentamicin or streptomycin were the same as those of isolates susceptible to less than or equal to 2,000 micrograms of aminoglycoside per ml. These results suggest that TMP-SMX and TMP alone could prove useful in the treatment of serious enterococcal infections, including infections by strains with high-level resistance to aminoglycosides.

Cytotoxic lymphocytes generated in vivo with acute measles virus infection.

We studied the generation of cytotoxic lymphocytes in adults during an outbreak of acute measles virus infection. Nine patients were studied determining in particular whether virus-specific cytotoxic T lymphocytes could be directly detected in peripheral blood during this acute infection. The cytotoxicity of PBL was assayed against measles virus-infected and uninfected phytohemagglutinin-induced blast cells of matched and mismatched HLA, A, B, and C types, in a standard 4-h 51Cr release assay. There was greater cytotoxicity against measles virus-infected than uninfected target cells in at least one sample from every patient. In 4 patients this preferential lysis of virus infected cells was greater (a difference of more than 10% virus-specific lysis) against HLA-matched than mismatched targets. This preference for HLA A and B matched infected target cells was also clearly seen when the effector PBL were depleted of FC receptor bearing cells. The other 5 subjects exhibited no evidence of preferential lysis of HLA-matched measles virus-infected cells. All 9 patients limited the spread of measles virus infection and recovered equally from the acute infection. These studies provide some evidence to suggest that MHC-restricted virus-specific CTL are detectable in human peripheral blood during acute measles virus infection, albeit only with low frequency, but are not necessarily associated with recovery from disease.

Endogenous Aeromonas hydrophila endophthalmitis.

Aeromonas hydrophila as the etiologic agent of endophthalmitis is rare, having only been reported in association with a perforating injury of the eye. We describe a case of isolated spontaneous, endogenous endophthalmitis due to this agent, with no apparent source.

Treatment of penicillin-resistant Neisseria gonorrhoeae with oral norfloxacin.

Norfloxacin, an orally administered quinoline carboxylic acid that is structurally related to nalidixic acid, has been shown to be highly active in vitro against penicillinase-producing Neisseria gonorrhoeae. Ninety-two men with culture-proved gonococcal urethritis, 46 per cent with penicillinase-producing N. gonorrhoeae, and 27 per cent with non-penicillinase-producing N. gonorrhoeae that was resistant to penicillin were given either 1200 mg of norfloxacin divided into two equal oral doses four hours apart (59 patients) or 2 g of spectinomycin intramuscularly (33 patients). All patients in both treatment groups were cured. No adverse reactions were reported in either group. We conclude that a two-dose, single-day regimen of orally administered norfloxacin is effective therapy for uncomplicated urethritis caused by penicillin-resistant strains of N. gonorrhoeae.