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Abstract
Background: Acinetobacter baumannii (A. baumannii) is an important bacterium due to its frequent recovery as a multidrug-resistant pathogen in hospital settings. Its antimicrobial resistance capacities made it an important challenge to health care. Colistin has been adopted as the last resort drug for managing infections associated with A. baumannii and many other multidrug-resistant Gram-negative bacteria (MDR-GNB). Because of the rise in the use of colistin for the treatment of MDR-GNB, the evolution and spread of colistin-resistant bacteria is possible thus raising a potential threat to public health. However, we have chosen to focus on A. baumannii, a member of the ESKAPE pathogen group, because of its importance in infectious cycles and the paucity of information on this pathogen from the community in Mexico. This study aimed to assess the distribution of the class 1 integron (int1), antimicrobial resistance genes, and virulence genes in A. baumannii isolates collected from rivers, along the hydrological sub-region of the Soto La Marina water system in Tamaulipas, Mexico.
Methods: Thirty-two aquatic samples, including one control from the San Fernando River, were analyzed for A. baumannii using culture methods with CHROMagar™ Acinetobacter and orientation media. Presumptive species identification was performed using the VITEK® 2 Compact system (bioMérieux). Antimicrobial susceptibility was tested using the VITEK® 2 Compact system (broth microdilution) and Kirby-Bauer disc diffusion on Mueller–Hinton agar. In addition, the data were analyzed using descriptive statistics. Isolates were screened for mobile colistin resistance (mcr) gene variants (mcr-1, mcr-2, and mcr-3), virulence genes, and int1 using Polymerase Chain Reaction.
Results: Eight Acinetobacter spp. were recovered from five rivers. including five. A. baumannii strains and three. A. iwoffi strains. A. baumannii isolates showed resistant and intermediate resistance profiles to antimicrobials most frequently used to treat Acinetobacter infections such as colistin, meropenem ceftazidime, cefepime, ampicillin/sulbactam and piperacillin/tazobactam. The Multiple Antibiotic Resistance (MAR) index of three bacterial strains (60%) was >0.2 meaning they originated from high-risk sources of antibiotic contamination. A. baumannii strains in this study were found to carry int1 (20%), mcr-3 (40%), the standard virulence gene fimH (20%), and the dangerous virulence gene rmpA (20%). Moreover, MDR A. baumannii (20%) was detected in the San Fernando River.
Conclusions: The findings of this study show that A. baumannii harbors the colistin-resistant gene (mcr-3), which is associated with resistance to colistin, an antibiotic regarded as a last-resort treatment for MDR infections. Detecting int1 and virulence genes in extra-hospital environments poses a significant risk to human health. Additionally, the MAR index of some A. baumannii is >0.2 showing the importance of this water system as a possible reservoir and source of transmission of pathogenic A. baumannii.
Recommended Citation
Olaniyan, Tunde Olarinde; Martínez Vázquez, Ana Verónica; Fernández Dávila, Susana Silvia; Escobedo Bonilla, Cesar Marcial; and Garcia, Virgilio Bocanegra, "Virulence analysis, characterization of integron, and antimicrobial resistance genes in strains of Acinetobacter baumannii recovered from the hydrological sub-region of Soto La Marina, Tamaulipas" (2025). Research Symposium. 166.
https://scholarworks.utrgv.edu/somrs/2025/posters/166
Included in
Biotechnology Commons, Environmental Microbiology and Microbial Ecology Commons, Pathogenic Microbiology Commons
Virulence analysis, characterization of integron, and antimicrobial resistance genes in strains of Acinetobacter baumannii recovered from the hydrological sub-region of Soto La Marina, Tamaulipas
Background: Acinetobacter baumannii (A. baumannii) is an important bacterium due to its frequent recovery as a multidrug-resistant pathogen in hospital settings. Its antimicrobial resistance capacities made it an important challenge to health care. Colistin has been adopted as the last resort drug for managing infections associated with A. baumannii and many other multidrug-resistant Gram-negative bacteria (MDR-GNB). Because of the rise in the use of colistin for the treatment of MDR-GNB, the evolution and spread of colistin-resistant bacteria is possible thus raising a potential threat to public health. However, we have chosen to focus on A. baumannii, a member of the ESKAPE pathogen group, because of its importance in infectious cycles and the paucity of information on this pathogen from the community in Mexico. This study aimed to assess the distribution of the class 1 integron (int1), antimicrobial resistance genes, and virulence genes in A. baumannii isolates collected from rivers, along the hydrological sub-region of the Soto La Marina water system in Tamaulipas, Mexico.
Methods: Thirty-two aquatic samples, including one control from the San Fernando River, were analyzed for A. baumannii using culture methods with CHROMagar™ Acinetobacter and orientation media. Presumptive species identification was performed using the VITEK® 2 Compact system (bioMérieux). Antimicrobial susceptibility was tested using the VITEK® 2 Compact system (broth microdilution) and Kirby-Bauer disc diffusion on Mueller–Hinton agar. In addition, the data were analyzed using descriptive statistics. Isolates were screened for mobile colistin resistance (mcr) gene variants (mcr-1, mcr-2, and mcr-3), virulence genes, and int1 using Polymerase Chain Reaction.
Results: Eight Acinetobacter spp. were recovered from five rivers. including five. A. baumannii strains and three. A. iwoffi strains. A. baumannii isolates showed resistant and intermediate resistance profiles to antimicrobials most frequently used to treat Acinetobacter infections such as colistin, meropenem ceftazidime, cefepime, ampicillin/sulbactam and piperacillin/tazobactam. The Multiple Antibiotic Resistance (MAR) index of three bacterial strains (60%) was >0.2 meaning they originated from high-risk sources of antibiotic contamination. A. baumannii strains in this study were found to carry int1 (20%), mcr-3 (40%), the standard virulence gene fimH (20%), and the dangerous virulence gene rmpA (20%). Moreover, MDR A. baumannii (20%) was detected in the San Fernando River.
Conclusions: The findings of this study show that A. baumannii harbors the colistin-resistant gene (mcr-3), which is associated with resistance to colistin, an antibiotic regarded as a last-resort treatment for MDR infections. Detecting int1 and virulence genes in extra-hospital environments poses a significant risk to human health. Additionally, the MAR index of some A. baumannii is >0.2 showing the importance of this water system as a possible reservoir and source of transmission of pathogenic A. baumannii.
