Inthe present study the prevalence of stones with infection was 68(30.7%).
Hamidshafi et al has reported a Positive stone culture as 10(22.2%) . Sohshany HL et al has reported 47%culture positivity in calculi and urine specimens.(15)Mariappan et al hasshowed a stone culture positivity of 35.2%. Wealso compared the culture positivity rate of infection stone with the urinesamples collected from the same patients and 49 samples (72.05%) showed culturepositivity in their respective midstream urine specimens also.
Urinary calculi can obstructthe urine outflow pathway leading onto stasis of urine which in turn can leadto attachment and multiplication of bacteria on to the epithelium leading toinfection. Studies have indicated that positivity in calculi culture and Midstream urine specimen can be indicatorsfor urospesis indicating the importance of culturing both the specimens forbacterial pathogens.(ref to be added). .
(16). Studies havefound that Patients with positive urinary calculi culture are more prone for postoperative sepsis. Theincidence of infection stones ranging from 2.7 % in Asian region to 42.9% in SubsharanAfrican region (9).Various studies have also reported high level of concordancebetween the bacteria isolated from the stone and urine culture.
(10,11,12). Studieshave indicated the association of various risk factors like age, sex, Diabetes,Hypertension,previous history of renal stones and family history of renalstones with positive stone culture(ref???) . In the present study significantassociation between Stones with infection and Diabetes mellitus, Hypertension,obesity , age and family history of renal stones were observed similar to astudy by Arias Vegaz R et al and A.
triencheiri(13,14). Among the gram negative isolates frominfected calculi good susceptibility was observed for Amikacin andofloxacin.Among the gram positive bacteria good susceptibility was observed foramikacin and nitrofurantoin .we also observed the presence of drug resistantbacteria like MRSA (11 isolates) and ESBL (25 isolates) among the urinarystones with infection by phenotypic and genotypic methods.(Drug resistancegenes for ESBL like SHV and TEM identification by Polymerase chain reaction )Wealso observed the presence of drug resistant organism like ESBL, MRSA amongboth the isolates obtained from the urine culture as well as from the calculi.Such finding is alarming as the presence of such drug resistant organism canlead on to treatment failure if not treated appropriately. Hence performingculture of the urinary stone determining the antibiotic susceptibility patternalong with the detection of drug resistance by phenotypic or genotypic methodsbefore initiating therapy will be of immense value for adequately treating theinfection. The information regarding the resistance pattern can help thephysicians in selecting an appropriate drug for therapy and the therapy can beindividualised taking into account the risk factors and chances of drugresistance for better treatment outcomes and hospital infection control(17).
Regularlyupdated surveillance of local microbial prevalence and resistance patterns areneeded to guide the empiric therapy for UTIs.Asresistance is becoming more widespread, prudent use of antimicrobials isimperative and, as asymptomatic bacteriuria is typically benign in the elderly,antibiotics should not be prescribed without clinical signs of UTI. The use ofantibiotics as suppressive therapy or long-term prophylaxis may no longer bedefensible.Urinary tract infections (UTIs) are one of themost common bacterial infection encountered in a health care setting(1).Urolithiasis is also a commonly encountered condition among adults with aprevalence of 3-5% and they may occur as an outcome of alteredmetabolic conditions or concomitant urinary tract infection(2). Urolithiasiscan cause obstructive symptoms leading onto stasis of urine which in turn leadson to adhesion and multiplication of bacteria to the uroepithelium leading ontourinary tract infection.
Urinary calculi that occur following urinary tractinfection are known as infection stone and those stones that are complicated asa result of UTI are the metabolic stones . These metabolic stones trap bacteriafrom co existent UTI (3,4). Urolithiasis associated with infection can resultin persistant bacterial infectionDue to extensive use of antibiotics the multidrugresistant bacteria are being isolated from urinary tract infections and urinarycalculi cuture which are difficult to eradicate leading onto increasedmortality and morbidity and posing a serious threat. Identification of bacteriain the calculi and therapy with appropriate antibiotic will also preventrecurrence.(4)The present study aims to isolate the bacterialagents from urinary calculi and from midstream urine specimen, to study theantibiotic susceptibility pattern,to identify the drug resistant phenotypeslike MRSA and ESBL.
The present study also aims at identifying the associationbetween various risk factors and positive stone culture.Urinarycalculi were thoroughly washed in sterile saline and crushed with asepticprecautions. The crushed particles were inoculated into 5ml thioglycollatebroth and incubated at 37?cfor 18-24 hours. After incubation Subcultures were done onto Blood agar andMacConkey agar. The growth of the bacterial isolates were identified as perstandard microbiological techniques.PhenotypicConfirmatory testThe isolates that showed resistance forceftazidime and cefotaxime wereconfirmed to be ESBL producer by testing along with the combination of 10 mgclavulanic acid and the isolates with a 5mm increase in zone of inhibition forthe combination ceftazidime / clavulanic acid (30µg/10µg) were confirmed asESBLs. MIC Reductiontest(Agar dilution method): The MIC of the isolates were tested forvarious concentrations of 3rd generation cephalosporin (cefotaxime and ceftazidime) from 0.
5µg to 2048µg / ml of agar and the MICdetermined. Minimum inhibitory concentration (MIC) was the lowest concentrationat which no visible growth occurs.MIC reduction test wasperformed by combining the third generation cephalosporin (cefotaxime andceftazidime) with 4ug/ml of clavulanic acid from 0.5ug to 2048ug / ml of agarand the MIC was determined. More than or equal to three doubling dilutionreduction in the MIC of 3rd generation cephalosporins in thepresence of clavulanic acid indicates production of ESBL.