Abstract
BackgroundThe defense mechanisms of the urinary tract are attributed mainly to the innate immune system and the urinary tract urothelium which represent the first line of defense against invading pathogens and maintaining sterility of the urinary tract. There are only a few publications regarding cathelicidin (LL-37) and a urinary tract infection (UTI). This study was done to investigate the plasma and urine levels of human LL-37 in patients with UTI.MethodsA case-control study was conducted at Omdurman Hospital, Sudan during the period from August 2014 to May 2017. The cases were patients with confirmed UTI and the controls were healthy volunteers without UTI. Sociodemographic and clinical data were obtained from each participant using questionnaires. Urine cultures and antimicrobial susceptibility were tested. Plasma and urine levels of LL-37 were determined using an enzyme-linked immunosorbent assay (ELISA) kit. SPSS (version 16.0) was used for analyses.ResultsCases and controls (87 in each arm) were matched according to their basic characteristics. Compared with controls, the median (inter-quartile) LL-37 level in plasma [2.100 (1.700–2.700) vs. 1.800 (1.000–2.200) ng/ml, P = 0.002] and in urine [0.900 (0.300–1.600) vs. 0.000 (0.000–1.000) ng/mg creatinine, P < 0.001] was significantly higher in cases. There was no significant difference in the median plasma [2.1 (1.7–2.9) vs. 2.000 (1.700–2.400) ng/ml, P = 0.561] and urine [0.850 (0.275–2.025) vs. 0.900 (0.250–1.350) ng/mg creatinine, P = 0.124]. The uropathogenic Escherichia coli (UPEC) was the predominant isolate, n = 38 (43.7%). LL-37 levels between the E. coli isolates and the other isolated organisms. There was no significant correlation between plasma and urine LL-37 levels (r = 0.221), even when the data of the cases were analyzed separately.ConclusionLL-37 is notably increased among patients with UTI compared with normal control subjects. Severity of UTI increases the levels of LL-37. The increased level was not only in the patient’s urine, but has also been observed in the patient’s plasma. Detection of increased levels of LL-37 could help to differentiate subjects with suspected UTI. Accordingly, LL-37 could act as a good marker for diagnosing UTIs.
Highlights
The defense mechanisms of the urinary tract are attributed mainly to the innate immune system and the urinary tract urothelium which represent the first line of defense against invading pathogens and maintaining sterility of the urinary tract
The common organisms isolated from the 87 cases were Escherichia coli (38, 43.7%), Klebsiella pneumoniae (16, 18.4%), Enterobacter cloacae (4, 4.6%), Pseudomonas aeruginosa (4, 4.6%), Proteus mirabilis (3, 3.4%), Acinetobacter baumannii (3, 3.4%), Acinetobacter lwoffii (3, 3.4%), Klebsiella oxytoca (2, 2.3%), Morganella morganii (2, 2.3%), Pantoea agglomerans (3, 3.4%), Pseudomonas luteola (2, 2.3%), Enterococcus faecalis (2, 2.3%), Enterococcus faecium (2, 2.3%), Staphylococcus aureus (2. 2.3%), Staphylococcus saprophyticus (1, 1.1%)
Our findings provide the first evidence in adult and young children of both genders that the level of LL-37 correlates with positive urine culture in cases of urinary infections
Summary
The defense mechanisms of the urinary tract are attributed mainly to the innate immune system and the urinary tract urothelium which represent the first line of defense against invading pathogens and maintaining sterility of the urinary tract. There are many routes by which microbes can reach the urinary tract and the kidneys [6, 7], the defensive mechanisms of the innate immune system, in addition to the urinary tract urothelium, represent the first line of defense against these invading pathogens helping the urinary tract to remain sterile [1] Dysfunction in these immune mechanisms may lead to acute disease, massive infection and tissue destruction, which may turn the ‘friendly’ host defense into troublesome and disturbing enemies and give rise to disease, in addition to long-term complications such as hypertension and chronic kidney disease [1, 8]. Progression to renal scarring and permanent impairment of renal function and tissue destruction may occur [9, 10]
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