Serum antibodies study in recurrent urinary tract infectionVidya N Acharya, Neela H Mehta, Surangi K Jadav
Department-Division of Nephrology-Department of Medicine; K.E.M. Hospital, Bombay 400012, India
Correspondence Address: Source of Support: None, Conflict of Interest: None PMID: 501674
Source of Support: None, Conflict of Interest: None
Serum antibodies were studied in 187 cases of Urinary Tract Infection (UTI) divided into two groups. Group I consisted of 126 patients with 128 infections who had significant bacteriuria. 90 (70.3%) of these infections were associated with significant antibody response (> 1:320) at the beginning of the study. It was further observed that uropathogens of all kinds were capable of producing antibody titre response. In the follow up study of 105 infections, it was noted that in 40.9% of infections inspite o f negative urine culture, elevated antibody response persisted even after 3 months. In Group II, 61 patients with history of recurrent UTI with or without evidence of pyelonephritis were studied for responses again` various serotypes of E. coli which were found to be common uropathogens. In this group too, majority o f the patients manifested elevated antibody response even when they had sterile urine at the time o f the study.
Urinary tract infections caused by Coliform organisms in man elicit a measurable antibody response as has been noted by several workers. ,,, They have further stated that the level of antibody response would help in the localisation of the site of UTI. A critical antibody titre level of 1: 320 or more was obtained by
Over a period of two years (Nov. '75 to Oct. '77), a total of 187 cases were studied. These patients were divided into two groups.
Group I: It consisted of 126 patients who had significant bacteriuria (105 organisms/ml) which was determined by Dip-Slide inoculum method  from 3 consecutive mid-stream urine samples or on obtaining any growth from a single sample of urine drawn by suprapubic bladder aspiration method or by sterile disposable plastic catheter. In this group the antibody titre was determined against patient's own organisms by using indirect haemagglutination method.  The follow up study was done for a variable period of 3 to 12 months in 77 patients from Group I having 105 infections. The primary urinary pathogens were stored in a refrigerator and the subsequent antibody titres were determined against these primary cultures as well as against reinfecting organisms, if isolated.
Group II: The remaining 61 patients who had sterile urine at the time of the study were included in this group. However, this group of patients had several episodes of UTI over a period ranging from 1 to 10 years or were diagnosed to have chronic pyelonephritis, by the combined criteria established clinically, radiologically and histologically by kidney biopsy. In this group, the antibody titres were determined against E. coli serotypes 01,02,04,06, 07 and 09. These E. coli : strains were found to be the common urinary pathogen in the city of Bombay.  14 patients of this group were followed up for 3 to 12 months to detect antibody titre response against the E. coli serotypes
Group I: Out of 126 patients, 124 had UTI with single organism and two patients had multiple organisms. The antibody titre response against these 128 urinary pathogens is shown in [Table 1]. It is evident that majority of the organisms were able to produce significant levels of antibodies (> 1:320) in the serum indicating that the majority of uropathogens had antigenicity. Furthermore, it is noted that infections due to E. coli, Proteus group, Pseudomonas aeruginosa, A-D group and Staphylococcus aureus were able to produce antibodies in a large proportion of patients right at the beginning of the infection.
The follow up results of 105 infections were classified into two categories as follows.
Category I: There was recovery of primary infection with no relapse as judged by the conventional criteria of urine culture becoming negative and remaining persistently negative. This occured in 88 (83.8%) infections. In this category the results of antibody titre could be grouped as mentioned below.
(i) In 21 infections (23.9%) the high antibody titre returned to insignificant level.
(ii) Antibody titre remained elevated in 36 (40.9%) infections.
(iii) 31 infections (35.2%) were associated with insignificant level of antibody all throughout.
Category II: In this category, there were 17 infections (16.2%) which were persistent or were associated with relapse after initial recovery. In this category, the elevated antibody titres were found in 11 infections (64.8% ). [Figure 1] shows the over all results of 105 infections from follow up of 77 patients.
In group II, out of 61 patients, where cultures were sterile, the elevated antibody titres were observed in 15 patients against E. coli serotype 01, in 21 patients against E. coli-02, in 16 patients against E. coli-04, in 17 patients against E. coli 06, in 28 patients against E. coli-07 and in 19 patients against E. coli-09. These results revealed that several patients had elevation of antibodies against more than one serotype of E. coli. In this group 14 patients were followed up and majority of these patients had still persistent high antibody titres. The classical examples of two such patients, viz., (1) one patient (ZK) who had recurrent UTI but no evidence of pyelonephritis and (2) Second patient (B.S.) who had recurrent UTI in the past but had proved to have pyelonephritis are shown in [Table 2] and [Table 3].
The serum antibody response in UTI depends on the presence of specific antibodies in the patient's serum against the 0 antigen of their own infecting microorganisms causing the UTI. The present study revealed that significant levels of antibody titres were obtained against majority of the urinary pathogens. These included infections due to E. coli, Pseudomonas aeruginosa, Proteus group, A-D group and Staphylococcus aureus [Table 1]. Recently Johny et al  have studied the antibody titre responses in different clinical groups of UTIs which were caused by a variety of Gram negative bacteria. They also obtained significant levels of antibodies in these groups of patients.
It was interesting to observe from the follow up results of 105 infections in Group I that 40.9% of the infections continued to manifest elevated antibody levels over long periods of time even when primary infection had long cleared off. The same was also observed in 61 cases of Group II who had sterile urine, but high antibody titres were found against more than one strains of E. coli serotypes. The exact significance of these antibody elevation needs to be deciphered. It could be attributed in certain patients, to the presence of intermittent bacteriuria as observed by Faireley et a1  even after a period of years or by the presence of degraded bacterial forms as noted in 82% of cases with intractable symptoms and scarred kidneys.  Secondly, the above observation of elevated antibody titre in presence of sterile urine could be very enlightening on the basis of cross reacting antigen (lipopolysaccharide 0 antigens) in majority of urinary pathogens except Proteus and Pseudomonas strains. However, this observation is quite contrary to the routine belief that elevated antibodies against an infection is protective in nature as far as UTI is concerned. Is this the vulnerable group likely to develop sequelae of recurrent UTI? This is quite likely and could be proved only on very long term follow up of cases of UTI.
We are grateful to the Seth G. S. Medical College and K,E.M. Hospital Research Society for giving us a grant to carry out this work. We thank the Dean, Dr. C. K. Deshpande of Seth G.S. Medical College and K.E.M. Hospital for the permission to carry out the above study and to publish this paper.
[Table 1], [Table 2], [Table 3]