Neisseria gonorrhoeae strains isolated in Hong Kong: in vitro susceptibility to 13 antibiotics

Ro 13-9904 has high in vitro activity, as does cefotaxime, against 57 Haemophilus influenzae and 60 Neisseria gonorrhoeae strains, including 5 and 11 filactamase-producing strains in each group, respectively.The appearance of 8i-lactamase-producing Haemophilus influenzae (2, 9) and Neisseria gonorrhoeae strains (1, 7) resistant to ampicillin and penicillin has prompted the search for alternative safe and effective drugs which are not affected by the enzyme. The second-and thirdgeneration cephalosporins, including cefamandole, cefuroxime, cefoxitin, and cefotaxime, have shown promising results in this respect. Recently, a new semisynthetic cephalosporin, Ro 13-9904 (W.H.O. approved generic name, ceftriaxone), has also been shown to have high in vitro activities against many gram-negative bacteria (8, 10). We therefore determined, by the agar dilution technique, the in vitro susceptibility of 57 H. influenzae and 60 N. gonorrhoeae strains to Ro 13-9904, and the results were compared with those of penicillin, ampicillin, and six other cephalosporins.H. influenzae strains were identified by their morphology, growth characteristics, and X-and V-factor requirements. All strains except two were isolated from sputum specimens of patients with respiratory tract infections, mostly exacerbation of chronic bronchitis. A total of five ,Blactamase-producing Haemophilus strains, identified by the filter-paper chromogenic cephalosporin test (6), were found among the sputum isolates, and two type B H. influenzae strains isolated from cerebrospinal fluid were non-,B-lactamase producers. The strains were kept at -20°C in tryptic soy broth (Difco) containing 0.5% yeast extract, 0.5% soluble hemoglobin (Oxoid), and 20% glycerol (vol/vol) until ready for susceptibility testing. The 60 N. gonorrhoeae strains, including 11 ,B-lactamase-producing strains, the sources of the antibiotics, and the agar dilution technique have been described in a previous report (5). Ro 13-9904 was supplied by F. Hoffmann-La Roche Co. A standardized inoculum of 103 colony-forming units per ml was used for all bacterial strains throughout this study. The test medium was Mueller-Hinton agar (Difco) supplemented with 1% hemoglobin (Oxoid) and 1% supplement B (Difco) for both Haemophilus and gonococcal strains.The activity of Ro 13-9904 and eight other ,Blactam antibiotics against H. influenzae and N. gonorrhoeae strains is shown in Table 1. Ro 13-9904 and cefotaxime were the most active compounds tested. Both drugs showed extremely high in vitro activities (minimal inhibitory concentration, -0.125,g/ml) against all Haemophilus and gonococcal strains, including the 5 and 11 /8-lactamase-producing strains of each group, respectively. All of the H. influenzae and N. gonorrhoeae strains were susceptible to the second-generation cephalosporins cefuroxime, cefamandole, and cefoxitin, and none of the strains required minimal inhibitory concentrations of >4 ,ug/ml. In contrast, a great proportion of H. influenzae strains were resistant to the firstgeneration cephalosp...

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In Vitro Susceptibility of Haemophilus influenzae and Neisseria gonorrhoeae to Ro 13-9904 in Comparison with Other β-Lactam Antibiotics

Ng¹,

Chau

Arnold

1981

“…The appearance of strains of Neisseria gonorrhoeae resistant to penicillin as well as to other commonly used antibiotics (1,2,4,5,8,(10)(11)(12)(13)(14)(15)(16)18) has stimulated research for newer compounds with potential antimicrobial activity. The 2-acetylpyridine thiosemicarbazones, a newly synthesized group of compounds with in vitro antimalarial activity (7), have also shown antibacterial activity in vitro against some strains of N. gonorrhoeae and N. meningitidis (3).…”

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confidence: 99%

“…Twenty-five clinical isolates of N. gonorrhoeae obtained from the Latin American Center for Sexually Transmitted Diseases in San Juan, P.R., were studied. The identity of the isolates was confirmed by standard methods (9,11). The isolates were routinely tested for the presence of P-lactamase by the nitrocefin chromogenic test (Glaxo Laboratories, Greedford, Middlesex, U.K.) (12).…”

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confidence: 99%

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In vitro susceptibility of Neisseria gonorrhoeae to 2-acetylpyridine thiosemicarbazones

Christenson¹,

Rodriguez²,

Gorbea³

et al. 1985

MICs of 20 2-acetylpyridine thiosemicarbazones and penicillin were determined for 25 clinical isolates of I8-lactamase-positive and P-lactamase-negative Neisseria gonorrhoeae strains. The compounds most active against the I8-lactamase-producing strains were the N4,N4-disubstituted derivatives and the thiosemicarbazone derivatives of the 2-acetylpyridines, followed by the other compounds related to the 2-acetylpyridine thiosemicarbazones.

“…There have been numerous studies reporting on the in vitro susceptibility of gonococci to antimicrobial agents (3,4,(12)(13)(14). In virtually all such studies, however, there is no mention of the colonial type(s) selected for this study; it is assumed that no specific selection has been made as to particular colony type.…”

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confidence: 99%

Gonococcal opacity variants: susceptibility to antimicrobial agents

Salit¹,

Bond²

1982

We tested the susceptibility of 34 pairs of isogenic opaque and transparent colony variants of gonococci to nine antimicrobial agents. Only 20% of the opaque and transparent minimal inhibitory concentrations were discordant, and the mean minimal inhibitory concentrations were not significantly different. Selection of opacity variants is, therefore, not necessary for routine susceptibility testing.