Antibiotic Resistance of Acinetobacter spp. Isolates from the River Danube: Susceptibility Stays High

Abstract

Acinetobacter spp. occur naturally in many different habitats, including food, soil, and surface waters. In clinical settings, Acinetobacter poses an increasing health problem, causing infections with limited to no antibiotic therapeutic options left. The presence of human generated multidrug resistant strains is well documented but the extent to how widely they are distributed within the Acinetobacter population is unknown. In this study, Acinetobacter spp. were isolated from water samples at 14 sites of the whole course of the river Danube. Susceptibility testing was carried out for 14 clinically relevant antibiotics from six different antibiotic classes. Isolates showing a carbapenem resistance phenotype were screened with PCR and sequencing for the underlying resistance mechanism of carbapenem resistance. From the Danube river water, 262 Acinetobacter were isolated, the most common species was Acinetobacter baumannii with 135 isolates. Carbapenem and multiresistant isolates were rare but one isolate could be found which was only susceptible to colistin. The genetic background of carbapenem resistance was mostly based on typical Acinetobacter OXA enzymes but also on VIM-2. The population of Acinetobacter (baumannii and non-baumannii) revealed a significant proportion of human-generated antibiotic resistance and multiresistance, but the majority of the isolates stayed susceptible to most of the tested antibiotics.

Bacterial isolates harboring antibiotics and heavy-metal resistance genes co-existing with mobile genetic elements in natural aquatic water bodies

“…We observed the domination of Acinetobacter sp. in contract with the previous findings ( Kittinger et al, 2017 ), reporting Acinetobacter sp., as in higher prevalence with antibiotic resistance in freshwater bodies of Austria. The 16S rRNA nucleotide sequences of bacterial isolates showed 99–100% homology with previously submitted clinical and environmental isolates indicating that bacteria in this study might have originated from domestic sewage and or hospital effluent.…”

Multidrug-Resistant and Clinically Relevant Gram-Negative Bacteria Are Present in German Surface Waters

“…The multidrug-resistance (MDR) status of seven clinically relevant species (Figure 2) of the isolates was evaluated and varied between 3.8% of a respective species ( A. baumannii complex) to 100% ( C. freundii, E. cloacae, E. coli, K. oxytoca , and K. pneumoniae , Figure 2). The low number of MDR A. baumannii is concordant to data from Austria (Kittinger et al, 2017) where only 4.4% of the A. baumannii isolates were MDR. These MDR-isolates were mostly third generation cephalosporin resistant, but also Carbapenem non-susceptible isolates were present within the characterized isolates ( n = 7) including two isolates of P. aeruginosa (9w-9, 10w-5), A. baumannii complex (6w-8, 8s-4), K. oxytoca (11w-2, 12w-10) and one E. cloacae complex isolate (12w-5) (Supplementary Table S4).…”

Antimicrobials and Antibiotic-Resistant Bacteria: A Risk to the Environment and to Public Health

“…One study found the abundance of tetracycline-resistant and fluoroquinolone-resistant bacteria to increase in river water samples further downstream [103]. Multi-drug resistant opportunistic bacteria carrying genes resistant to carbapenem, a last-resort antibiotic, have also been found in surface waters such as ponds, lakes, and rivers, representing a major challenge to public health [84,104,105]. The concentrations of ARBs and ARGs are usually higher at the point of effluent discharges from WWTWP but gradually become reduced downstream from the discharge point [106,107].…”