High Rate of Reduced Susceptibility to Ciprofloxacin and Ceftriaxone among Nontyphoid Salmonella Clinical Isolates in Asia

Abstract

This multinational study from Asia revealed that reduced susceptibility to ciprofloxacin (MIC, 0.125 to 1 g/ml) in nontyphoid Salmonella isolates was common in Taiwan (48.1%) and Thailand (46.2%) and in S. enterica serotype Choleraesuis (68.8%) and S. Virchow (75.0%) from all countries. Reduced susceptibility to ceftriaxone (MIC, 2 to 8 g/ml) remained uncommon in Asia, except in Taiwan (38.0%) or in S. Typhimurium (25.0%) from all countries.Nontyphoid Salmonella bacteria, with more than 2,500 serotypes, usually cause diarrheal diseases in humans that may be complicated by extraintestinal infections, such as bacteremia, meningitis, and osteomyelitis (11). Resistance to antimicrobial agents, including fluoroquinolones and expanded-spectrum cephalosporins, has been a serious problem worldwide. Nontyphoid salmonellosis has been rampant in Asia (7); however, data on the antimicrobial susceptibilities, as well as the prevalence, of various serotypes in many Asian countries after 2000 have been lacking.During 2003 to 2005, 400 clinical isolates of nontyphoid Salmonella bacteria were randomly collected from 11 medical centers in seven Asian countries (Table 1) and transported to the central laboratory in Samsung Medical Center, Seoul, Korea, for serogrouping and serotyping using O and H antisera, respectively (Difco Laboratories, Detroit, MI). Susceptibilities to ciprofloxacin, tetracycline, ceftriaxone, ampicillin, chloramphenicol, and trimethoprim-sulfamethoxazole were determined by a broth microdilution method, and the results were interpreted according to the breakpoints for MICs suggested by the NCCLS (10). For statistical analysis, isolates in the "intermediate" category were deemed "resistant" in this study. Concomitant resistance to at least three of the six antibiotics tested was defined as multidrug resistance (MDR). Isolates with ciprofloxacin MICs of 0.125 to 1 g/ml were defined as having "reduced susceptibility" to ciprofloxacin (9). Similarly, "reduced susceptibility" to ceftriaxone was defined as isolates showing ceftriaxone MICs of 2 to 8 g/ml (14). These definitions were proposed in previous reports to reflect the clinical therapeutic responses (9, 14). The 2 test and Student's t test were used to determine the significance of differences, and a P value of Ͻ0.05 was considered statistically significant.A total of nine serogroups (B, C1, C2, D, E, G, I, K, and M) and 82 serotypes were identified among the isolates tested. Serogroups B (34.8%) and D (25.0%) were the two leading serogroups in all areas except Philippines, where serogroup E (25 isolates, 53.2%) was most prevalent. The distribution of major serotypes among the countries is shown in Table 1. Overall, S. enterica serotype Enteritidis and S. Typhimurium were the two most-prevalent serotypes except in Philippines, Singapore, and Thailand, where S. Weltevreden was either the most-or second-most-prevalent serotype. In Sri Lanka and Thailand, the most-prevalent serotypes were S. Agona and S. Stanley, respectively. S. Choleraesuis was relatively mor...

Prevalence and antimicrobial resistance of Salmonella serotypes isolated from retail chicken meat and giblets in Iran

“…Antimicrobial resistance in Salmonella serotypes has been a global problem, with rates increasing from between 20% and 30% in the early 1990s to as high as 70% in some countries at the turn of the century [43,44]. The results of antimicrobial resistance tests of 111 Salmonella isolates to 16 antimicrobials are shown in Table 3.…”

Serotyping and Antimicrobial Susceptibility of <i>Salmonella</i> spp.: Nationwide Multicenter Study in Korea

“…In Asia, S. Enteritidis is also the most common in Hong Kong, Singapore, and Korea, whereas Salmonella serotypes Typhimurium, Weltevreden, and Stanley are the most prevalent in Taiwan, the Philippines, and Thailand (20). In Korea, serogroup D has been the most common among Salmonella spp.…”

Ceftriaxone Resistance and Genes Encoding Extended-Spectrum ^|^beta;-Lactamase among Non-Typhoidal Salmonella Species from a Tertiary Care Hospital in Kuala Lumpur, Malaysia

“…A study in Taiwan (7) showed that between January 1999 and December 2002, only 1.02z of nontyphoidal Salmonella isolates were resistant to ceftriaxone. On the other hand, a multinational study (10) involving randomly collected non-typhoid isolates during 2003 to 2005 from 7 Asian countries (not including Malaysia) showed that reduced susceptibility to ceftriaxone (defined in that study as an MIC of 2-8 mg/ml) was uncommon in Asian countries, except Taiwan (38z), and in S. Typhimurium (25z) in all countries. It also reported a ceftriaxone resistance rate of 3.0z, compared with 10.8z in Taiwan (10).…”

“…On the other hand, a multinational study (10) involving randomly collected non-typhoid isolates during 2003 to 2005 from 7 Asian countries (not including Malaysia) showed that reduced susceptibility to ceftriaxone (defined in that study as an MIC of 2-8 mg/ml) was uncommon in Asian countries, except Taiwan (38z), and in S. Typhimurium (25z) in all countries. It also reported a ceftriaxone resistance rate of 3.0z, compared with 10.8z in Taiwan (10). When comparing ceftriaxone resistance rates, the criteria used for interpretation as``resistant'' should be noted because the CLSI published revised ceftriaxone breakpoints in 2010 (14).…”

“…(1). Ceftriaxone resistance among Salmonella spp., however, has been reported worldwide (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13), and common resistance mechanisms include the production of plasmid-mediated AmpC b-lactamases and extended-spectrum b-lactamases (ESBLs) (2)(3)(4)(5)(7)(8)(9). A previous study involving 78 clinical isolates of Salmonella spp.…”