Penicillin

About: Penicillin is a research topic. Over the lifetime, 17916 publications have been published within this topic receiving 368480 citations. The topic is also known as: penicillin antibiotic & PCN.

Multiple changes of penicillin-binding proteins in penicillin-resistant clinical isolates of Streptococcus pneumoniae.

Abstract: Penicillin-binding properties and characteristics of penicillin-binding proteins (PBPs) were investigated in several clinical isolates of Streptococcus pneumoniae differing in their susceptibilities to penicillin (minimal inhibitory concentration [MIC], 0.03 to 0.5 microgram/ml) and compared with the penicillin-susceptible strain R36A (MIC, 0.07 microgram/ml). Several changes accompanied the development of resistance: the relative affinity to penicillin of whole cells, isolated membranes, and two major PBPs after in vivo or in vitro labeling decreased (with increasing resistance). Furthermore, one additional PBP (2') appeared in four of five relatively resistant strains with an MIC of 0.25 microgram/ml and higher. PBP 3 maintained the same high affinity toward penicillin in all strains under all labeling conditions.

Effect of Treatment Regimens for Neisseria gonorrhoeae on Simultaneous Infection with Chlamydia trachomatis

Abstract: We evaluated the effect of treatment of gonorrhea on simultaneous Chlamydia trachomatis infection by randomly assigning 293 heterosexual men and 246 heterosexual women with gonorrhea to receive one of the following treatment regimens: (1) 4.8 million units of aqueous procaine penicillin plus 1 g of probenecid, (2) nine tablets of trimethoprim-sulfamethoxazole daily for three days, or (3) 500 mg of tetracycline four times a day for five days. Among the men, gonococcal infection was cured in 99 per cent given penicillin plus probenecid, 96 per cent given trimethoprim-sulfamethoxazole, and 98 per cent given tetracycline. Among the women, only 90 per cent given tetracycline were cured, in contrast to 97 per cent given penicillin plus probenecid and 99 per cent given trimethoprim-sulfamethoxazole. Chlamydial infection, present in 15 per cent of the men and 26 per cent of the women, was cured in 30 of 32 patients given trimethoprim-sulfamethoxazole and 27 of 29 given tetracycline, but in only 10 of 23 given penicillin plus probenecid. Among chlamydia-positive patients, postgonococcal urethritis in men and cervicitis in women occurred more often in patients given penicillin plus probenecid. Salpingitis developed in 6 of 20 women given penicillin plus probenecid, but in only 1 of 26 given trimethoprim-sulfamethoxazole and in none of 24 given tetracycline. We conclude that the use of penicillin plus probenecid alone for gonorrhea in heterosexual patients carries an unacceptably high risk of postgonococcal chlamydial morbidity. Trimethoprim-sulfamethoxazole and tetracycline were highly effective against both pathogens and were well tolerated in men, but both drugs caused frequent side effects in women. The failure of tetracycline to cure gonorrhea in 10 per cent of women argues against its use alone; treatment with penicillin followed by tetracycline has been recommended for further trial.

Undescribed toxin in pseudomembranous colitis.

Abstract: A girl aged 12 developed pseudomembranous colitis after a short course of oral penicillin. She had no history of adverse reaction to penicillin before or after the illness. No pathogenic bacteria, mycoplasmas, or viruses were found in her faeces, but they did contain a toxin. Toxin was also found in four of five other patients with pseudomembranous colitis but not in six specimens obtained from patients with diarrhoea caused by other disorders. Further studies may show that pseudomembranous colitis is caused by a bacterial toxin.

Gonococci causing disseminated gonococcal infection are resistant to the bactericidal action of normal human sera.

Abstract: The susceptibility of strains of Neisseria gonorrhoeae to the bactericidal action of normal human sera was determined for isolates from patients with disseminated gonococcal infection and uncomplicated gonorrhea. Serum susceptibility was correlated with penicillin susceptibility and auxotype. 38 of 39 strains (97%) of N. gonorrhoeae from Seattle patients with disseminated gonococcal infection were resistant to the complement-dependent bactericidal action of normal human sera. 36 of these were inhibited by less than or equal to mug/ml of penicillin G and required arginine, hypoxanthine, and uracil for growth on chemically defined medium (Arg-Hyx-Ura- auxotype). 12 of 43 isolates from patients with uncomplicated gonorrhea were also of the Arg-Hyx-Ura-auxotype, inhibited by less than or equal to 0.030 mug/ml of penicillin G, and serum resistant. Of the 31 remaining strains of other auxotypes isolated from patients with uncomplicated gonorrhea, 18 (58.1%) were sensitive to normal human sera in titers ranging from 2 to 2,048. The bactericidal action of normal human sera may prevent the dissemination of serum-sensitive gonococci. However, since only a small proportion of individuals infected by serum-resistant strains develop disseminated gonococcal infection, serum resistance appears to be a necessary but not a sufficient virulence factor for dissemination. Host factors such as menstruation and pharyngeal gonococcal infection may favor the dissemination of serum-resistant strains. Since serum-resistant Arg-Hyx-Ura strains are far more frequently isolated from patients with disseminated gonococcal infection than serum-resistant strains of other auxotypes, Arg-Hyx-Ura-strains may possess other virulence factors in addition to serum resistance.