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

Abstract

Aeromonas species are well distributed in freshwater environments, and their natural susceptibility to antimicrobials renders them interesting candidates for the survey of antimicrobial resistance in freshwater milieu. Water samples were collected from Kat and Tyume rivers in the Eastern Cape province of South Africa, and a total of 45 isolates identified as Aeromonas species were recovered from the two rivers. All Aeromonas isolates were resistant to oxacillin, penicillin, clindamycin, cephalothin, vancomycin, and rifamycin, while appreciable susceptibilities (89.3 : 94.1%, 82.1 : 94.1%, 85.7 : 88.2%, and 92.9 : 88.2%) were observed against ciprofloxacin, chloramphenicol, nitrofurantoin, and gentamicin from Kat and Tyume rivers, respectively. Multiple antibiotic resistance (MAR) indices ranged from 0.016 to 0.044 for the two rivers. Class 1 integron was detected in about 20% of the isolates, and all the isolates except one showed ability to produce biofilm in vitro as weak producers (53.33%), moderate producers (15.56%), and strong producers (28.9%). This investigation provides a baseline data on antibiotic resistance as well as the adhesive characteristics of Aeromonas isolates from Tyume and Kat rivers in the Eastern Cape province of South Africa.

Detection of antibiotic resistance, virulence gene determinants and biofilm formation in Aeromonas species isolated from cattle

“…The recognition of Aeromonas as an emerging foodborne pathogen is on the increase (Igbinosa, 2014), hence the focus of the study. The animal farms sampled were governmental and commercial farms comprising of different farm animals including cattle.…”

“…Phenotypically, yellow colonies were picked as presumptive Aeromonas species and purified. Aeromonas were identified based on morphological, cultural and biochemical characteristics (Quinn et al 2002;Igbinosa and Okoh 2012). The isolates were confirmed by examining Gram staining characteristics and performing oxidase, catalase and biochemical reactions.…”

“…The cycling conditions (Bio-Rad My Cycler™ Thermal Cycler) were as follows: pse1 -PSE-1/ CARB-2 (blaP1 class A β-lactamase) (initial denaturation at 96°C for 5 min, followed by 30 cycles of denaturation at 96°C for 30 s, annealing at 60°C and a single extension of 5 min at 72°C); bla TEM (3 min at 93°C, 40 cycles of 1 min at 93°C, 1 min at 55°C, 1 min at 72°C and, finally, 7 min at 72°C) (Igbinosa and Okoh 2012).…”

“…Virulence factors in Aeromonas are associated with the establishment of infection and are thought to be involved in the development of disease (Nawaz et al 2010;Nagar et al 2011). Aeromonas causes disease in both humans and animals (Dashe et al, 2013;Igbinosa 2014). The presence of Aeromonas in the faeces of animals could be symptomatic or asymptomatic.…”

Biofilm formation of <i>Salmonella</i> species isolated from fresh cabbage and spinach

“…Isolates were sub-cultured on nutrient agar plates incubated for 24 h at 37 o C. Colonies were picked from the agar plates, and suspended in normal saline (0.85% w/v), and the density of the suspension was adjusted to 0.5 McFarland standard. The bacterialsuspension was spread on the Mueller Hinton agar plates using a sterile swab stick, allowed to dry, and impregnated with antibiotic disk (Igbinosa et al, 2013 (Cevahir et al, 2008). …”