Convergent acquisition of antibiotic resistance determinants amongst the <i>Enterobacteriaceae</i> isolates of the Mhlathuze River, KwaZulu-Natal (RSA)

Abstract

The Mhlathuze River has become a major reservoir for antibiotic-resistant microbes and a wide pool of antibiotic resistant genes with the environmental isolates exists in this water system. The ability of commensal organisms to carry resistant genes of clinical importance and their ability to transfer such genes to other bacteria are of greater concern than phenotypic measurements. Forty-three Enterobacteriaceae isolates, which were capable of resisting more than 4 different classes of antibiotics, were used for the molecular characterisation of antibiotic resistances. It was found that 58% of these multiple antibiotic-resistant isolates possess the Class 1 integron. Amongst these 25 isolates with positive detection of the Class 1 integron, the beta-lactamase gene (pse) was the most common, being present in 44% of these integrons. The aminoglycoside-resistant gene was detected in 16% of these integrons and 24% of Class 1 integrons contained two genes coding for sulphonamide resistance and for quaternary ammonium compounds resistance. A high degree of genotypic diversity and the lack of correlation between antimicrobial resistance patterns and molecular types of the isolates suggest convergent acquisition of resistance determinants by genetically unrelated strains rather than epidemic spread of resistant isolates in the community. Of the tested environmental isolates, 56% transferred their plasmids as well as their antibiotic resistance profiles to the recipient cells. The possibility of transmission of resistant genes between bacteria (especially pathogenic) which invade human and animal populations within this river poses a health risk to the communities who are dependent on this river for water consumption.

High prevalence of multiple-antibiotic-resistant (MAR) Escherichia coli in river bed sediments of the Apies River, South Africa

“…From the first sampling point (DAS) to the last one (AP9), the river flows through areas with WWTWs, agricultural settings, informal settlements and urban areas, each of which could contribute directly (WWTWs) or indirectly (agriculture) through run-offs to the presence of MAR in the Apies River. The results of the water column observed in this study agree with the high prevalence of ABR E. coli in surface waters reported by previous studies carried out in South Africa (Lin et al 2004;Lin and Biyela 2005;Kinge et al 2010). The highest contribution to the prevalence of ABR E. coli obtained in this study could have originated from the WWTWs situated along the river.…”

“…As a result, river water is a main alternative water source and might be used for drinking without prior treatment. Water quality research studies including the occurrence of antibiotic-resistant strains of bacteria have focused mainly on the water column (Lin et al 2004;Lin and Biyela 2005;Kinge et al 2010). Information on microbial sediment quality in general is highly lacking, and subsequently, studies on the occurrence of antibiotic-resistant strains of bacteria in sediment are very few.…”

Incidence of diverse integrons and β-lactamase genes in environmental Enterobacteriaceae isolates from Jiaozhou Bay, China

“…This proportion is slightly higher than what was found in some aquatic environments (Lin and Biyela 2005), but much higher than other aquatic environments (Rosser and Young 1999;Roe et al 2003;Henriques et al 2006;Ozgumus et al 2007). It has been found that there is a strong correlation between the presence of integrons and multidrug resistance ).…”

Antibiogram, Adhesive Characteristics, and Incidence of Class 1 Integron inAeromonasSpecies Isolated from Two South African Rivers

“…Lukkana et al [41] has documented the presence of class 1 integron in Aeromonas hydrophilia isolated from Nile Tilapia, in Thailand. Rosser and Young [48] documented the incidence of class 1 integrons in 3.6% of bacteria isolated from the Tay estuary, and Lin and Biyela [49] reported the presence of class 1 integron in 58% of Enterobacteriaceae isolated from Mhlathuze river in KwaZulu-Natal, Republic of South Africa, and this may imply a wide distribution and persistence of class 1 integron in South African aquatic milieu. The presence of integron in a wide variety of bacteria and in different habitat substantiates the horizontal mobility and stability of this gene capture system [50].…”