Detection of intracellular bacterial communities and biofilms in urinary tract infections with Escherichia coli using staining protocols

Table 1 Demographic characteristics of the study participants, n (%)

Variables	Overall (n = 73)
Age (range) years
Male	24-70
Female	23-70
Gender
Male	29 (39.8)
Female	44 (60.2)
Number of UTI episodes in the past
NIL	73 (100)
> 1	0 (0)
Urine culture identification for E. coli
Positive	73 (100)
Negative	0 (0)

UTI: Urinary tract infection; NIL: Nothing; E. coli: Escherichia coli.

Table 2 Performance evaluation of staining protocols for intracellular bacterial community detection (n = 73), n (%)

Method	Number of samples with IBCs	Interpretation
Sternheimer-Malbin stain	15 (20.6)	Highlighted the urine sediment morphology, but the visualization of the intracellular bacteria against the background was vague
Wright-Giemsa stain	19 (26.0)	Better than Sternheimer-Malbin and Safranin stains for visualization of intracellular clusters
Safranin stain	11 (16.4)	Weak staining for intracellular bacteria; lowest sensitivity among the stains
Immunofluorescence (anti-E. coli)	27 (37.0)	Highest sensitivity due to specific antigen targeting

IBC: Intracellular bacterial community; E. coli: Escherichia coli.

Table 3 Scoring of intracellular bacterial communities within uroplakin cells by the four staining methods

Scoring1	Sternheimer-Malbin stain (n = 15)	Wright-Giemsa stain (n = 19)	Safranin stain (n = 11)	Immunofluorescence staining (n = 27)
Occasional	2	3	1	2
Few	4	1	2	9
Mild	1	2	2	1
Moderate	1	3	1	2
Plenty	7	10	5	13

¹Based on the number of intracellular bacterial communities within uroplakin cells, scoring was defined as: Occasional: < 5, few: 6-10, mild: 11-30, moderate: 31-60, plenty: > 61.

Table 4 Analysis of Biofilm formation by Escherichia coli urinary tract infection patients

	Strong/moderate biofilm	Weak/no biofilm
IBC positive (n = 27)	21	6
IBC negative (n = 46)	17	29

IBC: Intracellular bacterial community.