The Materials And Methods Biology Essay

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Urinary tract infection (UTI) is the most common acute infection which occurs in females. Females are more frequently affected by UTI (particularly cystitis) due to (1) colonization of urethra by colonic Gram-negative bacilli (2) close proximity of urethra to anus. (3) short length of urethra (about 4cm) and (4) sexual intercourse (Introduction of bacteria into the bladder). Three quarter of Urinary tract infections occur in pregnant women and one quarter in non-pregnant women. 10,3,4

Pregnant women are more prone than non-pregnant women to develop U.T.I. because of physiological changes in urinary tract during pregnancy. Beginning in 6th week reaching peak by 22nd to 24th weeks approximately 90% of pregnant women develop urethral dilation, which will remain until delivery (Hydronephrosis of pregnancy). Increased bladder volume and decreased bladder tone, along with decreased urethral tone, contribute to increase in urinary stasis and urethero reflux. Physiological increase in plasma volume during pregnancy decreases urine concentration. Up to 70% of pregnant women develop glycosuria, which encourages bacterial growth in the urine. Increase in urinary progestins and estrogens, may elevate the pH of urine and may lead to a decreased ability of the lower urinary tract to resist invading bacteria. These physiologic changes may all contribute to the development of urinary tract infections during pregnancy. 3

Microbiologically, urinary tract infection exists when pathogenic microorganisms are detected in the urinary tract. The infection is considered significant and requires treatment when more than 100 microorganism per millilitre of urine in symptomatic patient or > 100,000 organisms per ml of urine in asymptomatic patients with accompanying pyuria (<7 WBCs/ml) are present in properly collected specimen.11,1

Gram negative bacteria such as E. coli, Klebsiella spp. Serratia spp., Enterobacter spp. Pseudomonas spp. and some Gram positive bacteria particularly Enterococcus faecalis. Group B Streptococcus and Staphylococcus saprophyticus are usually detected in urinary tract infection. 1

With an increasing trend of antibiotic resistance among organism causing urinary tract infections, especially E. coli which accounts for the maximum cases of resistance to antibiotics[6]. Keeping in view the above facts there in a need to further test antibiotics not commonly used in the treatment of urinary tract infections like Ciprofloxacin, Norfloxacin, Amoxicillin, Cefazolin, Erythromycin, Ofloxacin, Ampicillin, Cloxacillin, Amikacin and Gentamycin. 3

Materials and Methods:

100 female attending the OPD of Hayes Memorial Mission Hospital and Jeevan Jyoti Hospital Allahabad, showing symptoms of urinary tract infections.

Specimen collection - Clean catch midstream urine specimens were collected in sterile bottles preferably prior to administering antibiotics. Before collecting a sample, genitalia should be cleaned with soap and water. The first part of urine is allowed to pass then without interrupting the urine flow, mid-portion of the stream is collected. The first portion of urine adequately flushes out the normal urethral flora.12

Transport - As urine is a good culture medium, specimens after collection should reach the laboratory with minimum delay, if this is not possible, the specimen is to be refrigerated at 4°C. 12

Sample processing:

Wet Mount - Urine sample was transferred into a tube then centrifuged and a drop of centrifuged deposit was taken on clean microscopic slide and then covered with a coverslip and seen under low power (10x) objective then focused under high power (40x) objective. Presence of pus cells, epithelial cells and bacteria were noted.

Isolation - Urine samples were mixed properly and using standard calibrated loop which delivered 0.001 ml of urine was used to inoculate on Blood agar. The samples were also plated on MacConkey’s agar. The plates were incubated at 37oC for 48 hours.

Identification - Samples which showed >100 colonies were taken as significant and bacterial identification was done as follows

A colony was picked from the plate and a oval smear prepared on a slide, Grams staining was performed and the slide were observed under 100X (Oil immersion) objectives. The bacteria were differentiated accordingly as Gram positive or Gram negative cocci or bacilli and whether the were in chains or cluster.

Gram positive and Gram negative bacteria were identified by standard biochemical tests. Antibiotic sensitivity testing of bacteria was done by Kirby Bauer method.


Of the 100 female patients selected for the study, 10 patients were found to be suffering from urinary tract infection. Among this 3 (30%) were caused by Gram positive bacteria (Staphylococcus aureus and 7 (70%) patients were caused by Gram negative bacteria (Escherichia coli).

The patients included in the study were placed in 3 age groups viz. 16-20, 21-25 and 26-30 years, with maximum number of patients in 26-30 age groups. A significant increase in the urinary tract infection was observed with increasing age of the study groups.

Considering the income and living conditions of the study group about (15%) the patients belonged to the lower socioeconomic strata. These patients revealed a significantly higher incidence of urinary tract infection as compared to middle and higher socioeconomic strata.

Among the patients included in the study 5 had primary gravida, 9 had secondary and the rest 16 were multiple gravida. Higher incidence of Urinary tract infection was observed in patients had primary gravida (40%) followed by multigravida (12.50%) and secondary (11.11%) gravida.

Among the patients included in the study 6 had first trimester 15 second trimester and therest were third trimester higher incidence of urinary tract infection was observed in patients of third trimester (22.22%) followed by first trimester (16.67%) and then second trimester (13.33%).

On the basis of N.C.C. L.S. guidelines, bacteria isolated from Urine samples were foundto be sensitive to amikacin, ciprofloxacin, Amoxycilin, Erthmromycin oflaxacin, while its showed resistance to following drugs viz Norfloxicin and Amicillin.

Discussion - This study was carried out to find incidence of urinary tract infection in women and to find out the different factors influencing development of UTI. Total 100 women were included in the study, 70 non-pregnant and 30 pregnant women.

In our study it was seen that out of 10 cases of UTI, maximum cases i.e. 6 (60%) were in the age group of 26-30 years.

Also, maximum patients suffering from UTI i.e. 6 patients (60%) were from lower socio economic group.

Incidence of UTI was significantly high in pregnant females (16.67%) as compared to non-pregnant working (7.5%). This is in accordance with general finding that UTI is more common in pregnant women than in non-pregnant women. However our incidence rate is higher than reported by Nath et al. and Lavanya et al. 10, 4

In pregnant females the highest incidence of UTI was seen in primigravida i.e. (40%) and in females who were in third trimester i.e. (22.22%)

In our study 70% isolates from UTI patients were Escherichia coli which is in accordance with the study of Nath et al who reported E. coli as the commonest isolate responsible for causing UTI.

Also, in a study conducted by Lavanya and Jogalakshmi, E. coli was the most common organism isolated which was sensitive to cephalexin, nitrofurantoin, amoxicillin and norfloxacin in decreasing order. 4

Our study, E. coli isolates from U.T.I. showed maximum sensitivity to ampicillin + sulbactam, sparfloxacin and gatifloxacin whereas minimum sensitivity towards co-trimaxazole, tetracycline and ceftizoxime. S. aureus isolates showed maximum sensitivity to Ampicillin+Sulbactam, Co-trimaxazole, Cefotaxime, Ciprofloxacin, Levofloxacin, Linezolid, Cloxacillin and minimum to Gentamicin.


The incidence of UTI amongst women was 10% and 3 main factors which influenced development of UTI were:

1. Sexually active age group between 26 â€" 30 years.

2. Low socio economic status as this may directly be related to lack of hygiene.

3. Pregnancy

Amongst pregnant females primigravida and those in 3rd trimester were seen to be at higher risk.

Good sensitivity was seen for antibiotics like Ampicillin + Sulbactam, Co-trimaxazole, Sparfloxacin and Gatifloxacin which can be used as an alternative to drugs like Norfloxacin, Nalidixic acid and Nitrofurantoin which are usual drug of choice for UTI.