LAUSR

Abstract Background Neisseria gonorrhea (NG) has a long history of gaining resistance to nearly all antimicrobials used for treatment since the 1930s, which makes susceptibility to last-line cephalosporins of dire importance. Horizontal gene transmission is highly prevalent among the Neisseria genus, with genetic fragments from common commensal Neisseria having been found in resistant NG strains. Globally, NG disproportionately affects men-who-have-sex-with-men (MSM) and nearly all ceftriaxone-resistant cases have been reported from pharyngeal samples. Our study aims to assess the impact of antibiotic usage on the antimicrobial susceptibility of oropharyngeal Neisseria spp. Methods MSM from Hanoi, Vietnam, were surveyed regarding antibiotic usage. Pharyngeal swabs were collected and cultured on chocolate and modified-Thayer–Martin agar. Neisseria spp. were subcultured, identified using MALDI-TOF, and antimicrobial susceptibility determined by E-test using NG CLSI MIC breakpoints to ciprofloxacin (CIP), cefixime (CFM), ceftriaxone (CRO), and cefpodoxime (CPD). Results The 225 MSM surveyed were young (mean age 23.9 years, std 4.4). In the past 6 months: 41.6% participants used any antibiotics, among whom 62.4% did not have a prescription; 6.6% used CFM (16.4% more were unsure), among whom 55.6% did not have a prescription; and 4.5% received CRO. From 72 swabs, 102 Neisseria isolates were obtained; N. flavescens (n = 59), N. perflava (n = 14), N. macacae (n = 8), N. sublfava (n = 7), N. gonorrhoeae (n = 5), N. mucosa (n = 3), N. meningitides (n = 3), N. cinerea (n = 2), and N. lactamica (n = 1). 
“Reduced susceptibility” status for any Neisseria spp. was 35.3, 10, 8, and 30% to CIP, CFM, CRO, and CPD, respectively; 61.8% were “resistant” to CIP. MSM who took any antibiotics in the past 6 months were almost twice as likely to have Neisseria spp. with reduced susceptibility to cephalosporins (CFM, CRO, or CPD), RR 1.8 (95% CI 1.1–3.2; P = 0.026) compared with non-antibiotic users. Conclusion Many MSM in Hanoi used antibiotics recently, often without a prescription. Antibiotic use was associated with antimicrobial “reduced susceptibility” of commensal Neisseria spp. to cephalosporins, possibly potentiating resistance acquisition by NG. Disclosures All authors: No reported disclosures.