Predominance of blaTEM and tetA genes in antibiotic-resistant Escherichia coli isolates from Laguna Lake, Philippines

Lakes are one of the sinks of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs); however, information on ARB and ARGs in lakes in the Philippines is scarce. In this study, Escherichia coli was isolated from the largest freshwater lake in the Philippines, Laguna Lake, to detect antibiotic resistance and the presence of ARGs. Broth microdilution assay (BMA) and molecular identification of five environmentally prevalent ARGs (strA, blaCTX-M, blaSHV, blaTEM, and tetA) were performed. The majority (75.70%) of the isolates harbored at least one of the targeted antibiotic genes. Multiplex PCR detected about 49.07% of the isolates had genes for extended-spectrum β-lactamases (ESBL), which were mostly represented by blaTEM (47.66%). The genes strA and tetA were observed in this study with detection frequencies of 29.91 and 45.33%, respectively. About 95.69% of thermotolerant E. coli isolates were non-susceptible to six different antibiotics using BMA. Nearly 37% of the isolates were found to be multidrug-resistant (MDR) with most isolates resistant to ampicillin (81.72%). Furthermore, the occurrence of ESBL genes was significantly correlated with tetA genes (P = 0.013). To date, this study is the first to report on the presence of MDR and thermotolerant E. coli in Laguna Lake, Philippines.

Distribution of carbapenemases and efflux pump in carbopenems-resistance Acinetobacter baumannii

Acinetobacter baumannii has emerged as an important pathogen related to serious infections and nosocomial outbreaks around the world. The aim of this study was to detect the distribution of carbapenemases and efflux pump in carbopenems-resistance Acinetobacter baumannii(CRAB). In this study, 100 isolates of CRAB were collected from clinical specimens. Agar dilution was conducted to determine the minimum inhibitory concentrations (MICs) to 15 kinds of antibiotic. Genes of carbapenemases and efflux pumps were amplified by PCR. The expression difference of pump genes was also analyzed by real-time PCR between CRAB and carbopenems- sensitive Acinetobacter baumannii (CSAB). We found that most antibiotics, including aminoglycosides, fluoroquinolones and cephalosporins showed high MIC values in CRAB. While, all isolates were sensitive to polymyxin B. Among CRAB, 54, 32 and 16 isolates were positive for SHV-12，PER-1 and TEM-1, respectively. 86 isolates were positive for OXA-23. 55, 33 and 5 isolates carried adeB, adeJ and adeE genes. The expression level of adeB in CRAB was ten times higher than that in CSAB. Moreover, isolates with single adeE gene were detected for the first time in Acinetobacter baumannii.

Distribution of carbapenemases and efflux pump in carbopenems-resistance Acinetobacter baumannii

Acinetobacter baumannii has emerged as an important pathogen related to serious infections and nosocomial outbreaks around the world. The aim of this study was to detect the distribution of carbapenemases and efflux pump in carbopenems-resistance Acinetobacter baumannii(CRAB). In this study, 100 isolates of CRAB were collected from clinical specimens. Agar dilution was conducted to determine the minimum inhibitory concentrations (MICs) to 15 kinds of antibiotic. Genes of carbapenemases and efflux pumps were amplified by PCR. The expression difference of pump genes was also analyzed by real-time PCR between CRAB and carbopenems- sensitive Acinetobacter baumannii (CSAB). We found that most antibiotics, including aminoglycosides, fluoroquinolones and cephalosporins showed high MIC values in CRAB. While, all isolates were sensitive to polymyxin B. Among CRAB, 54, 32 and 16 isolates were positive for SHV-12，PER-1 and TEM-1, respectively. 86 isolates were positive for OXA-23. 55, 33 and 5 isolates carried adeB, adeJ and adeE genes. The expression level of adeB in CRAB was ten times higher than that in CSAB. Moreover, isolates with single adeE gene were detected for the first time in Acinetobacter baumannii.

Antibiotic genes spread far and wide

The genes responsible for antibiotics can spread between the three domains of life—Archaea, Bacteria and Eukaryotes.