Deliberations on the impact of antibiotic contamination on dissemination of antibiotic resistance genes in aquatic environments

Abstract

The great success of antibiotics in treating bacterial infectious diseases has been hampered by the increasing prevalence of antibiotic resistant bacteria. Not only does antibiotic resistance threaten to increase the difficulty in treating bacterial infectious diseases, but it could also make medical procedures such as routine surgery and organ transplantations very dangerous to perform. Traditionally, antibiotic resistance has been regarded as a strictly clinical problem and studies of the problem have mostly been restricted to a clinical milieu. Recently, non-clinical environments, and in particular aquatic environments, have been recognised as important factors in development and dissemination of antibiotic resistance. Elevated concentrations of antibiotics in an environment are likely to drive a selection pressure which favours resistant bacteria, and are also believed to promote horizontal gene transfer among the indigenous bacteria. Antibiotic resistance genes are often located on mobile genetic elements such as plasmids and integrons, which have the ability to disseminate among taxonomically unrelated species. The environmental bacteria can thus serve as both reservoirs for resistance and hot spots for the development of new antibiotic resistance determinants.There is still a lack of data pertaining to how high antibiotic concentrations are necessary to drive a selection pressure in aquatic environments. The aim of this thesis is to determine the effect of high and low concentrations of antibiotics on environmental bacterial communities from different aquatic environments. In the studies performed, antibiotics were measured using liquid chromatography-mass spectrometry. Bacterial diversity and evenness were assessed using molecular fingerprints obtained with 16S rRNA gene-based denaturing gradient gel electrophoresis, and antibiotic resistance genes and class 1 integrons were quantified using real-time PCR.Water and sediment samples were collected from different rivers and canals in Pakistan. The environments differed in anthropogenic exposure from undisturbed to heavily contaminated. A general trend could be observed of high concentrations of antibiotics correlating to elevated concentrations of antibiotic resistance genes and integrons. Extremely high concentrations of antibiotic resistance genes and integrons were found in the sediments downstream of an industrial drug formulation site, which likely correlated to the high load of antibiotics found in the water. Antibiotic and antibiotic resistance gene concentrations were also shown to increase downstream of Ravi river, which flows through Lahore, a city of more than 10 million inhabitants. Rivers not impacted by anthropogenic contamination were found to contain antibiotics and resistance gene concentrations of similar levels as in Europe and the U.S. Similar measurements were performed in the Swedish river Stångån. The concentrations of antibiotic resistance genes and class 1 VI integrons were shown to increase in the river after it had passed...

Prevalence and classification of high antimicrobial resistant Staphylococcus aureus in wastewater eluted from poultry slaughterhouse

“…Vancomycin-resistant S. aureus (VRSA) is emerging rapidly in the environment since 1996 and, this has been highlighted in studies conducted by Lowy (2003) and Berglund (2014). In some cases, these strains might be MRSA and they are fully resistant to vancomycin.…”

“…Genes transfer can also occur through bacteriophage. It was reported that mecA gene encoded for the methicillin resistance in MRSA was found in the DNA of the bacteriophage (Colomer-Lluch et al, 2011;Berglund, 2014) through the transduction process. Bacteriophage acts as vehicles for antibiotic resistance genes.…”

“…Antibiotics are commonly placed in food animals for therapeutic use, prophylactic use, and subtherapeutic use (Landers et al, 2012). However, the overuse and misuse of antibiotics (Wright, 2010;Berglund, 2014) due to the widespread adoption of antibiotic use in food animals (Sarmah et al, 2006) had exacerbated the matter. This had caused the decreased efficiency of the antibiotics and reduced the therapeutic options (Appelbaum, 2012;Berglund, 2014 Nevertheless, the spread of MRSA among the general population -those not recently associated in a healthcare setting had been reported and increasing (CDC, 2013).…”

“…However, the overuse and misuse of antibiotics (Wright, 2010;Berglund, 2014) due to the widespread adoption of antibiotic use in food animals (Sarmah et al, 2006) had exacerbated the matter. This had caused the decreased efficiency of the antibiotics and reduced the therapeutic options (Appelbaum, 2012;Berglund, 2014 Nevertheless, the spread of MRSA among the general population -those not recently associated in a healthcare setting had been reported and increasing (CDC, 2013). The possibility of the general population contracting MRSA maybe from the food from animals that are fed with antibiotics, environment or direct human-animal contact.…”

“…Antibiotic resistant bacteria have become the biggest threats, creating outbreaks and increasing mortality rates. Berglund (2014) mentioned that in the European Union, there are over 25,000 deaths every year caused by antibiotic resistant bacteria. While Centers of Disease Control and Prevention (CDC) (2017) reported that at least 23,000 deaths were caused by antibiotic resistance in the United States.…”