Lead, silver nitrate and antibiotic resistance in bacteria isolated from Nile tilapia (Oreochromis niloticus) in anthropogenically polluted Lake Chivero, Zimbabwe

Figures & data

Figure 1. Sample collection point (Kamba Caravan Park station, Lake Chivero, Zimbabwe).

Table 1. Different groups, primary biochemical tests conducted, and bacteria identified in O. niloticus in Lake Chivero

Table 2. Prevalence percentages of the isolated bacteria

Figure 2. Overall bacterial sensitivity to the tested antibiotics

Table 3. Isolated bacteria and their resistance rates

Organism	Number of isolates tested	Tested antibiotics and their resistance rates (%)
		Tetracycline	Streptomycin	Neomycin	Gentamycin	Erythromycin	Cloxacillin	Lincomycin	Rifampicin	MDR (+/–)	MAR index
Proteus	7	57.1	28.6	14.3	00	14.2	57.1	85.7	57.5	+	0.88
Escherichia	35	28.6	57.1	11.4	00	80	68.6	88.6	77.1	+	0.88
Bacillus	13	61.5	00	7.6	00	7.6	53.8	100	100	+	0.75
Listeria	3	00	100	100	00	100	00	100	100	+	0.63
Staphylococcus	46	8.7	8.7	00	00	34.8	6.5	45.7	76	+	0.75
Aeromonas	26	15.4	50	9.2	00	38.5	00	88.4	76.9	+	0.75
Edwardsiella	12	8.3	00	00	00	16.7	00	100	83.3	+	0.50
Shigella	15	20	6.7	00	00	00	13.3	93.3	86.7	+	0.63
Overall resistance rates		22.3	28	8.9	00	38.2	25.5	79.6	79.6

Table 4. Tolerance of the isolated bacterial spp. to lead and silver nitrate

Organism	n	Metal concentrations with the number of resistant isolates
		Lead concentration (µg/ml)							Silver nitrate concentration (µg/ml)
		100	200	400	800	1600	R isolates	R %	100	200	400	800	1600	R isolates	R %
Proteus	7	5	3	2	2	1	3	42.9	4	3	1	1	1	3	42.9
Escherichia	35	19	18	11	5	0	18	51.4	23	24	17	11	7	24	68.6
Bacillus	13	6	4	2	1	0	4	30.8	5	3	1	0	0	3	23.1
Listeria	3	3	2	1	0	0	2	66.7	2	2	1	1	1	2	66.7
Staphylococcus	46	27	19	5	2	1	19	41.3	31	29	5	2	2	29	63
Aeromonas	26	21	18	12	3	0	18	69.2	24	23	17	13	3	23	88.5
Edwardsiella	12	9	5	2	0	0	5	41.7	7	4	2	2	1	4	33.3
Shigella	15	10	6	2	0	0	6	40	11	13	11	5	2	13	86.7
E. coli ATCC 25922		*							*
S. aureus ATCC 33862		*							*
Negative control		NG	NG	NG	NG	NG			NG	NG	NG	NG	NG

KEY: NG-no growthKEY: NG-no growth