Orman Betina E, Piñeiro Silvia A, Arduino Sonia, Galas Marcelo, Melano Roberto, Caffer Maria I, Sordelli Daniel O, Centrón Daniela
Departamento de Microbiología, Parasitología e Inmunología, Facultad de Medicina, Universidad de Buenos Aires, Argentina.
Antimicrob Agents Chemother. 2002 Dec;46(12):3963-70. doi: 10.1128/AAC.46.12.3963-3970.2002.
Molecular evolution of multiresistance in nontyphoid Salmonella spp. was investigated with 155 isolates obtained in Argentina from 1984 to 1998. In 74 isolates obtained from 1984 to 1988 resistance was associated with the presence of Tn3, Tn9, class I (In0) and II (Tn7) integrons, and the aac(3)-IIa gene. Extended-spectrum cephalosporin (ESC) resistance in Salmonella spp. emerged in 1989, and 81 isolates resistant to at least one ESC and one aminoglycoside were collected thereafter. Among these, two patterns of antimicrobial resistance mechanisms were found: from 1989 to 1992, resistance was related to the spreading of Tn1331 and bla(CTX-M-2), in addition to the persistence of In0 and Tn7. From 1993 to 1998, several integrons were added to the first pattern and three integron groups (IG), namely, IG1 (38% of the isolates), IG2 (51%), and IG3 (11%), were identified. At least two beta-lactamase genes were detected in 65% of the isolates (after 1989) by PCR analysis. Furthermore, five beta-lactamase genes, bla(CTX-M-(2)), bla(OXA-9), bla(OXA-2), bla(TEM-1), and bla(PER-2), were found in two isolates. The bla(CTX-M-2) gene was found in several complex sulI-type integrons with different rearrays within the variable region of class I integrons, suggesting evolution of these integrons in nontyphoid Salmonella. In conclusion, progressive acquisition and accumulation of plasmid-mediated resistance determinants occurred from 1984 to 1998 in nontyphoid Salmonella isolates of the most prevalent serovars from Argentina. It is suggested that antimicrobial resistance mechanisms in these bacteria may have been the consequence of plasmid exchange between Salmonella enterica serovar Typhimurium and Escherichia coli or Shigella flexneri and/or spreading of mobile elements from the nosocomial environment.
对1984年至1998年在阿根廷获得的155株非伤寒沙门氏菌的多重耐药性分子进化进行了研究。在1984年至1988年获得的74株菌株中，耐药性与Tn3、Tn9、I类（In0）和II类（Tn7）整合子以及aac(3)-IIa基因的存在有关。沙门氏菌属对超广谱头孢菌素（ESC）的耐药性于1989年出现，此后收集了81株对至少一种ESC和一种氨基糖苷类耐药的菌株。在这些菌株中，发现了两种抗菌耐药机制模式：1989年至1992年，耐药性与Tn1331和bla(CTX-M-2)的传播有关，此外In0和Tn7持续存在。1993年至1998年，在第一种模式中增加了几个整合子，并鉴定出三个整合子组（IG），即IG1（占分离株的38%）、IG2（51%）和IG3（11%）。通过PCR分析，在65%的分离株（1989年后）中检测到至少两个β-内酰胺酶基因。此外，在两株分离株中发现了五个β-内酰胺酶基因，即bla(CTX-M-(2))、bla(OXA-9)、bla(OXA-2)、bla(TEM-1)和bla(PER-2)。bla(CTX-M-2)基因存在于I类整合子可变区内具有不同重排的几个复杂sulI型整合子中，表明这些整合子在非伤寒沙门氏菌中发生了进化。总之，1984年至1998年期间，阿根廷最常见血清型的非伤寒沙门氏菌分离株中发生了质粒介导的耐药决定因素的逐步获得和积累。有人认为，这些细菌中的抗菌耐药机制可能是肠炎沙门氏菌血清型鼠伤寒亚种与大肠杆菌或福氏志贺氏菌之间质粒交换和/或医院环境中移动元件传播的结果。
