TAILIEUCHUNG - Chapter 137. Gonococcal Infections (Part 3)

Gonococcal Resistance to Antimicrobial Agents It is no surprise that N. gonorrhoeae, with its remarkable capacity to alter its antigenic structure and adapt to changes in the microenvironment, has become resistant to numerous antibiotics. The first effective agents against gonorrhea were the sulfonamides, which were introduced in the 1930s and became ineffective within a decade. Penicillin was then employed as the drug of choice for the treatment of gonorrhea. By 1965, 42% of gonococcal isolates had developed lowlevel resistance to penicillin G. Resistance due to the production of penicillinase arose later. Gonococci become fully resistant to antibiotics either by chromosomal mutations. | Chapter 137. Gonococcal Infections Part 3 Gonococcal Resistance to Antimicrobial Agents It is no surprise that N. gonorrhoeae with its remarkable capacity to alter its antigenic structure and adapt to changes in the microenvironment has become resistant to numerous antibiotics. The first effective agents against gonorrhea were the sulfonamides which were introduced in the 1930s and became ineffective within a decade. Penicillin was then employed as the drug of choice for the treatment of gonorrhea. By 1965 42 of gonococcal isolates had developed low-level resistance to penicillin G. Resistance due to the production of penicillinase arose later. Gonococci become fully resistant to antibiotics either by chromosomal mutations or by acquisition of R factors plasmids . Two types of chromosomal mutations have been described. The first type which is drug specific is a singlestep mutation leading to high-level resistance. The second type involves mutations at several chromosomal loci that combine to determine the level as well as the pattern of resistance. Strains with mutations in chromosomal genes were first observed in the late 1950s. As recently as 2004 chromosomal mutations accounted for resistance to penicillin tetracycline or both in 12 of strains surveyed in the United States. P-Lactamase penicillinase -producing strains of N. gonorrhoeae PPNG carrying plasmids with the Pcr determinant had rapidly spread worldwide by the early 1980s. N. gonorrhoeae strains with plasmid-borne tetracycline resistance TRNG can mobilize some P-lactamase plasmids and PPNG and TRNG occur together sometimes along with strains exhibiting chromosomally mediated resistance CMRNG . Penicillin ampicillin and tetracycline are no longer reliable for the treatment of gonorrhea and should not be used. Third-generation cephalosporins have remained highly effective as single-dose therapy for gonorrhea. Even though the minimal inhibitory concentrations MICs of ceftriaxone for certain strains may .

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