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Saudi Journal of Kidney Diseases and Transplantation
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Year : 2015  |  Volume : 26  |  Issue : 3  |  Page : 599-601
The effect of induced urinary tract infection during gestation in mother rats on infection in the neonates

1 Jahrom University of Medical Sciences, Jahrom, Iran
2 Department of Pediatrics, Jahrom University of Medical Sciences, Jahrom, Iran
3 Department of Microbiology, Jahrom University of Medical Sciences, Jahrom, Iran

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Date of Web Publication20-May-2015

How to cite this article:
Zarepour M, Moradpoor H, Emamghorashi F, Solhjo K, Rouhi R. The effect of induced urinary tract infection during gestation in mother rats on infection in the neonates. Saudi J Kidney Dis Transpl 2015;26:599-601

How to cite this URL:
Zarepour M, Moradpoor H, Emamghorashi F, Solhjo K, Rouhi R. The effect of induced urinary tract infection during gestation in mother rats on infection in the neonates. Saudi J Kidney Dis Transpl [serial online] 2015 [cited 2021 Jun 14];26:599-601. Available from: https://www.sjkdt.org/text.asp?2015/26/3/599/157412

To the Editor,

Urinary tract infection (UTI) is a common bacterial infection during pregnancy and the neonatal period. It is reported that UTI involves 0.07-2.23% of women during pregnancy and that pyelonephritis occurs commonly in the second half of pregnancy. [1],[2],[3],[4] The available literature regarding the impact of UTI during pregnancy on maternal complications and outcome of pregnancy is not consistent. [5],[6] Our previous study had shown that maternal UTI is a risk factor for the occurrence of neonatal UTI. [7] This earlier study was on humans, and many factors such as antibiotic consumption during pregnancy could have influenced the results. The present study was designed to determine the association between maternal and neonatal UTI in an animal model.

Fourteen pregnant rats (Sprague Dawley) weighing 254.33 ± 42.72 g obtained from the Laboratory Animal House of the Shiraz University of Medical Sciences, Shiraz, Iran were divided into two groups. In the first group, pyelonephritis was induced in the third trimester of pregnancy and the second group without infection served as the control group.

The bacterial strain used to induce pyelonephritis was Escherichia coli (H2O6, pap+), which was obtained from patients with pyelonephritis. After anesthetizing the rats, a small incision was made at the level of the kidney. The left kidney was exposed and 0.05 mL of an inoculum containing 10 [8] bacteria was injected into it. This technique, described earlier by Kaye, [9] produces severe pyelonephritis with extensive inflammation and abscess formation.

After the induction of pyelonephritis, the animals were locked up in separate cages. Following delivery, their neonates were divided into three groups based on days after birth on which the study was performed (first, third and seventh days after birth). In each group, two neonates of each mother were killed and both kidneys were aseptically removed using a midline abdominal incision. On the seventh day, rat mothers were also killed and their kidneys were removed. The kidney samples were transferred in sterile bottle for microbiologic study.

The study samples were homogenized in 3 mL of sterile saline at 4°C. Appropriate dilutions of homogenized kidneys were made and 10 μL samples were placed in triplicate on MacConkey agar. The types of organisms in the kidneys were determined after an incubation period of 18 h at 37°C. The kidneys were considered sterile when no colony-forming units (CFU) were detected.

The 14 pregnant rats had a mean weight of 254.33 ± 42.72 g. Overall, 101 neonates were born. Eight neonates were born dead and their kidneys were also evaluated for infection.

Sixty-one (53%) of the 115 kidney samples, including the mother's kidneys, were positive for infection. The most common organism was E. coli (39.1%), followed by non-hemolytic Streptococcus (12.2%) and coagulase-positive Staphylococcus (1.7%). E. coli was detected in all mothers and their neonates in the UTIinduced group. In the control group, three mothers showed a positive culture for E. coli. Two neonates of the control group had positive culture for coagulase-positive Staphylococcus.

Our results showed that the rate of UTI was significantly higher in neonates of mothers with UTI than in the control group [61.1% vs. 38.3%, P = 0.018; OR was 2.532 (95% CI 1.134-5.65)]. There was no difference in the rate of infection in the neonates tested on the first, third and seventh days after birth [Table 1].
Table 1: Results of kidney cultures based on days after birth in neonates of rats.

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The present study showed that UTI during pregnancy increases the risk of occurrence of neonatal UTI. Thus, it is recommended that urine culture should be a part of work-up in the post-partum follow-up of neonates of pregnant women with UTI. Acute antepartum pyelonephritis and asymptomatic bacteriuria are risk factors for pre-term delivery. [1],[9] Maternal UTI is associated with pre-eclampsia and intra-uterine growth retardation. [2] There is also a possible association between maternal UTI and cardiovascular malformations, and maternal infections contribute to about 40% of all adverse perinatal outcomes. [10],[11]

There are some risk factors for UTI in the neonatal period. Gender, formula-fed infants and use of vitamin D supplements increase the risk for UTI. [12],[13] Use of parenteral nutrition, intravascular catheter and associated infectious diseases contribute to increasing the frequency of neonatal UTI. [14]

In our study, UTI was induced in pregnant rats with uropathogenic strain (pap+). Uropathogenic strains of E. coli causing infection during pregnancy affect fetal outcome. Kaul et al presented a mouse model of pyelonephritisinduced pre-term birth. In the E. coli Dr + infected group, all fetuses (10 of 10) showed positive bacterial cultures compared with only 33% fetuses (four of 12) in the E. coli Dr infected group, indicating limited dissemination of E. coli Dr to the developing fetus compared with the E. coli Dr + group. [15]

We conclude that UTI during pregnancy can increase the risk of infection in neonates. We recommend proper evaluation and close follow-up of the neonates of mothers with UTI during pregnancy.

Conflict of Interest: None.

   References Top

Farkash E, Weintraub AY, Sergienko R, Wiznitzer A, Zlotnik A, Sheiner E. Acute antepartum pyelonephritis in pregnancy: A critical analysis of risk factors and outcomes. Eur J Obstet Gynecol Reprod Biol 2012;162: 24-7.  Back to cited text no. 1
Mazor-Dray E, Levy A, Schlaeffer F, Sheiner E. Maternal urinary tract infection: Is it independently associated with adverse pregnancy outcome? J Matern Fetal Neonatal Med 2009; 22:124-8.  Back to cited text no. 2
Sharma P, Thapa L. Acute pyelonephritis in pregnancy: A retrospective study. Aust N Z J Obstet Gynaecol 2007;47:313-5.  Back to cited text no. 3
Hill JB, Sheffield JS, McIntire DD, Wendel Jr GD. Acute pyelonephritis in pregnancy. Obstet Gynecol 2005;105:18-23.  Back to cited text no. 4
Chen YK, Chen SF, Li HC, Lin HC. No increased risk of adverse pregnancy outcomes in women with urinary tract infections: A nationwide population based study. Acta Obstet Gynecol Scand 2010;89:882-8.  Back to cited text no. 5
Bolton M, Horvath DJ Jr, Li B, et al. Intrauterine Growth Restriction Is a Direct Consequence of Localized Maternal Uropathogenic Escherichia coli Cystitis. PLoS One 2012;7:e33897.  Back to cited text no. 6
Emamghorashi F, Mahmoodi N, Tagarod Z, Heydari ST. Maternal urinary tract infection as a risk factor for neonatal urinary tract infection. Iran J Kidney Dis 2012;6:178-80.  Back to cited text no. 7
Sheiner E, Mazor-Drey E, Levy A. Asymptomatic bacteriuria during pregnancy. J Matern Fetal Neonatal Med 2009;22:423-7.  Back to cited text no. 8
Kaye D. The effect of water diuresis on spread of bacteria through the urinary tract. J Infect Dis 1971;124:297-305.  Back to cited text no. 9
Cleves MA, Malik S, Yang S, Carter TC, Hobbs CA. Maternal urinary tract infections and selected cardiovascular malformations. Birth Defects Res A Clin Mol Teratol 2008;82: 464-73.  Back to cited text no. 10
Andrews WW, Hauth JC, Goldenberg RL. Infection and preterm birth. Am J Perinatol 2000;17:357-65.  Back to cited text no. 11
Levy I, Comarsca J, Davidovits M, Klinger G, Sirota L, Linder N. Urinary tract infection in preterm infants: The protective role of breastfeeding. Pediatr Nephrol 2009;24:527-31.  Back to cited text no. 12
Katikaneni R, Ponnapakkam T, Ponnapakkam A, et al. Breastfeeding does not protect against urinary tract infection in the first 3 months of life, but vitamin D supplementation increases the risk by 76%. Clin Pediatr (Phila) 2009;48: 750-5.  Back to cited text no. 13
Falcão MC, Leone CR, D'Andrea RA, Berardi R, Ono NA, Vaz FA. Urinary Tract Infection in Full-term newborn infants: Risk factor analysis. Rev Hosp Clin Fac Med Sao Paulo 2000;55:9-16.  Back to cited text no. 14
Kaul AK, Khan S, Martens MG, Crosson JT, Lupo VR, Kaul R. Experimental Gestational Pyelonephritis Induces Preterm Births and Low Birth Weights in C3H/HeJ Mice. Infect Immun 1999;67:5958-66.  Back to cited text no. 15

Correspondence Address:
Dr. F Emamghorashi
Department of Pediatrics, Jahrom University of Medical Sciences, Post code: 7415713597, Jahrom
R Rouhi
Department of Microbiology, Jahrom University of Medical Sciences, Jahrom
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DOI: 10.4103/1319-2442.157412

PMID: 26022038

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