ORIGINAL ARTICLE
ANTIMICROBIAL SUSCEPTIBILITY OF COMMUNITY-ACQUIRED UROPATHOGENS IN GENERAL PRACTICE
Interpretation of culture results
Culture results were interpreted according to the guidelines of the Infectious Disease Society of America.5 The urinalysis results were used to assist in the diagnosis of UTI for those cultures showing <105 colony forming units/ml (cfu/ml). We referred to the studies of Stamm and other workers, who had redefined the acute urethral syndrome (women who experience symptoms of cystitis but who have urine cultures with <105 cfu/ml) as part of a spectrum of lower UTI in women.6-8
The diagnosis of UTI was made with the culture of a single bacterial species from the urine sample at a concentration of ≥ 105 cfu/ml. In compliance with the guidelines, females with uncomplicated acute cystitis have infection if the urine cultured between 103 and 105 cfu/ml, plus pyuria [defined as >10 leucocytes/μL of unspun urine]. A contaminated sample was defined as urine culture with < 103 cfu/ml or mixed growth.
Uncomplicated acute cystitis in women refers to an infection occurring in young, healthy, non-pregnant adult women without structural or renal dysfunction. Women older than 65 years of age with UTI were considered to have complicated infection as data of possible urologic dysfunctions were often not available to us during the study.
RESULTS
Demographic data
Two hundred and twenty-five urine samples (225 patients) fulfilled the criteria during the study period and were accepted for urinalysis, culture and sensitivity testing. The mean age of the respondents was 43 years (range 12-88 years). Of the respondents 78% were Chinese, followed by Malays 15%, and Indians and others 7%. Females made up 79% of the respondents. Fifty-two percent (117 cases) of the samples were positive for UTI by the criteria defined above. Age distribution of the cases is shown in Table 1.There was no growth of pathogens in 44.9% (101 cases) of the samples, and 3.1% (7 cases) of the samples were contaminated.
Table 1. Demographic data of patients with urinary tract infections
| Age groups (years) | Females, No. (%) | Males, No. (%) |
10 – 19 |
4 (3.4) | 1 (0.8) |
20 –29 |
29 (24.8) |
3 (2.6) |
30 – 39 |
16 (13.7) |
1 (0.8) |
40 –49 |
14 (12.0) |
3 (2.6) |
50 –59 |
18 (15.3) |
0 (0.0) |
| > 60 | 25 (21.4) | 3 (2.5) |
| Total | 106 (90.6) | 11(9.4) |
Uropathogens
E. coli was isolated from 77% (90 cases) of the positive samples. Other uropathogens isolated include Klebsiella spp. (10 cases), Proteus spp. (4 cases), Staphylococcus epidermidis (4 cases), Staphylococcus saprophyticus (4 cases), Streptococcus spp. (3 cases), Enterococcus spp(2 cases), and Citrobacter spp. (1 case).
Antimicrobial susceptibility
Overall, antimicrobial resistance was most common to ampicillin with 63.0% and ST with 40.1%. The pathogens were highly susceptible to most of the other antimicrobial tested (>90%) with the exception of pipemidic acid (see Table 2).
Subgroup Analysis
Sixty-four percent (75 cases) of the UTI patients were females with acute uncomplicated cystitis (see interpretation above). This constituted the largest group of patients. Sixty out of the 75 (80%) of the samples grew E. coli. Considering the acute uncomplicated cystitis in women alone, resistance of E. coli to ampicillin constituted 61%, and S-T resistance was 45%.
