Abstract:
The objective of this study was to investigate
the risks associated with the use of roof-harvested rainwater
(RHRW) and the implication of pigeons as the
most likely source of contamination by testing for antibiotic
resistance profiles of Escherichia coli. A total of
239 E. coli were isolated from thirty fresh pigeon faecal
samples (130 isolates), 11 RHRWtanks from three sites
in Pretoria (78) and two in Johannesburg (31). E. coli
isolates were tested against a panel of 12 antibiotics
which included ampicillin, amoxicillin, amikacin,
cefoxitin, ceftriaxone, chloramphenicol, ciprofloxacin,
cotrimoxazole, enrofloxacin, gentamicin, nalidixic acid
and tetracycline. In all samples, resistance to ampicillin
(22.7.9 %), gentamicin (23.6 %), amikacin (24 %), tetracycline
(17.4) and amoxicillin (16.9 %) were the most
frequently encountered form of resistance. However, a
relatively higher proportion of isolates from pigeon
faeces (67.3 %) were antibiotic resistant than those from
RHRW (53.3 %). The highest number of phenotypes
was observed for single antibiotics, and no single antibiotic
resistance was observed for chloramphenicol,
ceftriaxone, gentamicin, cefoxitin, cotrimoxazole, although
they were detected in multiple antibiotic resistance
(MAR) phenotypes. The highest multiple antibiotic
resistance (MAR) phenotypes were observed for a
combination of four antibiotics, on isolates from JHB
(18.8 %), pigeon faeces (15.2 %) and Pretoria (5.1 %).
The most abundant resistance phenotype to four antibiotics, Ak-Gm-Cip-T was dominated by isolates
from pigeon faeces (6.8 %) with Pretoria and Johannesburg
isolates having low proportions of 1.3 and 3.1 %,
respectively. Future studies should target isolates from
various environmental settings in which rainwater harvesting
is practiced and the characterisation of the antibiotic
resistance determinant genes among the isolates.
