Antibiotic Resistance Pattern of Uropathogens: An Experience from North Indian Cancer Patient.

Empirical treatment of urinary tract infections (UTIs) can be made evidence based if it is governed by the resistance pattern of common uropathogens. A retrospective study was carried out at a tertiary care cancer institute to identify the common uropathogens and to know their resistance profile. 20.82% of the outpatients' urine samples (community-acquired urinary tract infection (CA-UTI)) and 24.83% of the indoor patients' urine samples (hospital-acquired urinary tract infection (HA-UTI)) grew uropathogens. Escherichia coli was the predominant pathogen both in CA-UTI (68%) and HA-UTI (45%) followed by Klebsiella spp and Enterococcus spp. High level of resistance to fluoroquinolones and third generation cephalosporins was noted. Nitrofurantoin was found to be a reliable oral drug for treatment of most of the uropathogens.

INTRODUCTION

Urinary tract infections (UTIs) are the most commonly encountered infections in medical practice.[1] It is a major public health problem with an estimated 150 million cases per annum worldwide and with a financial burden of over 6 billion US dollar.[2] About 35% of all the UTIs are of nosocomial origin.[3] Most of the UTIs are treated empirically, the criteria for the selection of antimicrobial agent should be determined on the basis of the most likely pathogen and its expected resistance pattern in a geographical area.[4] Knowledge of infection epidemiology and the institutional resistance pattern can help physicians to select the optimal empirical treatment in critically-ill patients.[5] This retrospective study was designed to know the antibiotic resistance pattern of the uropathogens and to suggest an appropriate empirical treatment.

MICROBIOLOGY REPORT

It was a retrospective study carried out at a tertiary care cancer institute. Patient records were assigned into two categories. The first group comprising of urine samples from patients admitted in the hospital for at least 48 h (hospital-acquired UTI (HA-UTI)) and the second group from patients visiting the hospital on outpatient basis or admitted less than 48 h (community-acquired-UTI (CA-UTI)). Records of 13 months (15/7/2013-15/8/2014), of patients having UTI were studied and the uropathogens were recognized. Nonfermenters isolated were confirmed with repeat sample and were recorded when the same isolate with similar antibiotic susceptibility pattern was seen. Identification and antibiotic susceptibility of the bacterial pathogens was done using VITEK® 2 Compact (C) system version: 06.01 (Biomeriux, North Carolina, USA). Antibiotic susceptibility results were expressed according to the Clinical Laboratory Standards Institute M100-S23 (2013).[6]

Statistical analysis was done using Fisher's exact test.

The study involved a total of 1,530 consecutive urine samples, over a period of 13 months. A total of 1,028 (67.19%) samples were from suspected CA-UTI patients, of which 214 (20.82%) grew uropathogens. Four hundred and two (26.27%) samples were from suspected HA-UTI patients of which 98 (24.38%) grew uropathogens.

Gram negative bacilli accounted for 194 (90.65%), gram positive cocci for 12 (5.6%), and Candida spp for eight (3.74%) of the CA-UTI. Among the HA-UTI, 54 (55.10%) were gram negative bacilli, 18 (18.37%) were gram positive cocci, and 13 (13.27%) were Candida species.

Table 1 shows the uropathogens isolated from CA-UTI and HA-UTI patients.

Table 1

Frequency, percentage, and P-value of resistance of uropathogens isolated from CA-UTI versus HA-UTI patients

Escherichia coli was the predominant pathogen both in CA-UTI (68%) and HA-UTI (45%) followed by Klebsiella spp (18% in CA-UTI and 24% in HA-UTI) and Enterococcus spp (6% in CA-UTI and 21% in HA-UTI).

Among Escherichia coli, resistance to piperacillin tazobactum, third generation cephalosporins, carbapenems, ciprofloxacin, ampicillin, amoxycillin-clavulinic acid, and cefepime was more significantly associated with HA-UTI than CA-UTI [Table 1]. A comparison of resistance pattern of HA-UTI and CA-UTI among uropathogenic Escherichia coli from various studies in India is shown in Table 2. In case of Klebsiella spp and Enterobacter spp, resistance to piperacillin tazobactum; third generation cephalosporins, carbapenem, gentamicin, amikacin, ciprofloxacin, cefepime, trimethoprim, and sulfamethoxazole were more significantly associated with HA-UTI than CA-UTI [Table 1].

Table 2

Comparison of resistance pattern ofHA-UTI and CA-UTI amonguropathogenic Escherichia coli from various studies in India

Among nonfermenters, 80% isolates were resistant to aztreonam in HA-UTI compared to 25% of the isolates being resistant to aztreonam in CA-UTI. 25% of isolates were resistant to piperacillin tazobactumin CA-UTI when compared to 60% in HA-UTI.

None of the Enterococcus spp isolated in CA-UTI was resistant to nitrofurantoin compared to 28% of resistant isolates in HA-UTI.

CONCLUSION

Our data indicates that Escherichia coli is still the most frequent uropathogen, both in HA-UTI and CA-UTI. Ampicillin, cefuroxime, ceftriaxone, nalidixic acid, ciprofloxacin, and cotrimoxazole did not have good in vitro coverage for many of the uropathogens in this study. High level resistance against fluoroquinolones and third generation cephalosporins is a matter of concern, especially in CA-UTI where these are the drugs of choice. This could be due to indiscriminate use and availability of over-the-counter antibiotics. Nitrofurantoin still remains the best oral drug for treatment of most of the uropathogens. Updates on the knowledge of antibiotic resistance pattern of uropathogens is important for timely modifying the drugs of choice for empirical therapy which is required for early and effective treatment of the infection.[12]