Site of Action of Nitrofurantoin in Experimental Urinary Tract Infection

The effectiveness of nitrofurantoin in suppressing bacterial growth in the urinary tract was evaluated by using two different experimental models. Pyelonephritis was produced in rats by direct inoculation of 10(4)Escherichia coli in the medulla of left kidney. Ascending urinary tract infection was induced by inoculation into the urinary bladder of 10(7)Proteus mirabilis, after a partial cystectomy. Nitrofurantoin was shown to be effective in suppressing bladder bacteriuria, in preventing ascending pyelonephritis, and also in preventing bacterial multiplication in kidney tissue following direct inoculation.     

Macrophages Subvert Adaptive Immunity to Urinary Tract Infection

Urinary tract infection (UTI) is one of the most common bacterial infections with frequent recurrence being a major medical challenge. Development of effective therapies has been impeded by the lack of knowledge of events leading to adaptive immunity. Here, we establish conclusive evidence that an adaptive immune response is generated during UTI, yet this response does not establish sterilizing immunity. To investigate the underlying deficiency, we delineated the naïve bladder immune cell compartment, identifying resident macrophages as the most populous immune cell. To evaluate their impact on the establishment of adaptive immune responses following infection, we measured bacterial clearance in mice depleted of either circulating monocytes, which give rise to macrophages, or bladder resident macrophages. Surprisingly, mice depleted of resident macrophages, prior to primary infection, exhibited a nearly 2-log reduction in bacterial burden following secondary challenge compared to untreated animals. This increased bacterial clearance, in the context of a challenge infection, was dependent on lymphocytes. Macrophages were the predominant antigen presenting cell to acquire bacteria post-infection and in their absence, bacterial uptake by dendritic cells was increased almost 2-fold. These data suggest that bacterial uptake by tissue macrophages impedes development of adaptive immune responses during UTI, revealing a novel target for enhancing host responses to bacterial infection of the bladder.     

Transurethral Induction of Mouse Urinary Tract Infection

Uropathogenic bacterial strains of interest are grown on agar. Generally, uropathogenic E. coli (UPEC) and other strains can be grown overnight on Luria-Bertani (LB) agar at 37°C in ambient air. UPEC strains grow as yellowish-white translucent colonies on LB agar. Following confirmation of appropriate colony morphology, single colonies are then picked to be cultured in broth. LB broth can be used for most uropathogenic bacterial strains. Two serial, overnight LB broth cultures can be employed to enhance expression of type I pili, a well-defined virulence factor for uropathogenic bacteria. Broth cultures are diluted to the desired concentration in phosphate buffered saline (PBS). Eight to 12 week old female mice are placed under isoflurane anesthesia and transurethrally inoculated with bacteria using polyethylene tubing-covered 30 gauge syringes. Typical inocula, which must be empirically determined for each bacterial/mouse strain combination, are 10⁶ to 10⁸ cfu per mouse in 10 to 50 microliters of PBS. After the desired infection period (one day to several weeks), urine samples and the bladder and both kidneys are harvested. Each organ is minced, placed in PBS, and homogenized in a Blue Bullet homogenizer. Urine and tissue homogenates are serially diluted in PBS and cultured on appropriate agar. The following day, colony forming units are counted.Download video file.^{(109M, mp4)}     

Asymptomatic Urinary Tract Infection in Gynaecological Outpatients

In this study mid-stream specimens of urine were collected from all new patients attending a gynaecological outpatient department and tested for significant bacteriuria. Those having an asymptomatic infection were folloWed up, treated, and investigated adiologically.Of 1,506 women screened for bacteriuria 82 (5·4%) were found to have a persistent infection. The predominant organism was Escherichia coli, present in 83% of infections. Treatment with sulphonamides produced a good cure rate, which was improved by ampicillin given to failures. Some patients, however, had infections that persisted or recurred despite several antibiotics. The radiological investigations showed that a high proportion of women with asymptomatic urinary infection had severe renal disease which was quite symptomless. This was more pronounced in those with persistent or recurrent infections.     

Evaluation of New Urinary Tract Infection Screening Devices

Several new methods for detection of bacteriuria were studied to evaluate their usefulness as screening procedures. A new filter paper device incorporating dehydrated media and tetrazolium was found to be reliable when compared with the standard pour plate method in the laboratory and with the dip-slide method in a field test. It failed to detect yeasts and slowly growing streptococci. Antibiotics blocked the test when susceptible organisms were present. An agar-cup method was found to be quite reliable, but could be improved by use of differential media. The Griess test was confirmed in a small trial to be highly specific when used in conjunction with a first morning specimen, but of little value with random specimens. Phenzopyridine was found to give false positive reactions. The subnormal glucose test, although highly sensitive and specific, gave too many false positive tests to be useful other than as a screening method.     

儿童泌尿系感染的病原学分析

探讨目前儿童泌尿系感染病原体的变化趋势,为临床治疗提供实验依据。分析2008年1月至2009年10月住院治疗的357例尿细菌培养、支原体体外培养、衣原体检测阳性的泌尿系感染患儿病原体的分布情况。结果显示,尿细菌培养和支原体体外培养、衣原体检测前未应用过抗生素的患儿其阳性率为82.2%,而应用过抗生素的患儿其阳性率为31.8%,两者相比具有统计学意义(P0.01)。在检测的357例阳性标本中,革兰阴性杆菌占74.7%,其中以大肠埃希菌为主,占46.2%;革兰阳性球菌占14.8%,其中肠球菌占10.9%;真菌占3.1%,支原体占4.8%,衣原体占2.5%。临床要密切关注儿童泌尿系感染病原体的分布变迁情况,以便于为临床的诊断和治疗提供可靠的实验依据。     

Study of Childhood Urinary Tract Infection in General Practice

A study of bacteriuria was conducted among 426 of the 436 children under the age of 13 in a general practice in north-west London. Three girls and one boy were found to have asymptomatic bacteriuria, and a further girl with bacteriuria presented with abdominal pain and fever. The calculated incidence of urinary tract infection was 1·4% per annum. Most of the childhood urinary infections in this practice occurred before the age of 5 years, and the incidence of significant bacteriuria in this age group was 4·9% per annum. Five other children (four girls and one boy) in the practice were known to have had proved urinary tract infection. Of the total of eight children known to have had significant bacteriuria and investigated radiologically, three girls and two boys had radiological abnormalities in the urinary tract.Pyuria and proteinuria did not prove to be useful in the prediction of asymptomatic bacteriuria. Urinary tract infection with renal tract abnormality was found in this practice to be at least five times as common as diabetes in childhood.     

Suprapubic Bladder Aspiration in Diagnosis of Urinary Tract Infection

Suprapubic aspiration of the bladder has proved a safe and reliable method of collecting urine for culture. It avoids contamination of the specimen and dispenses with the need for colony counts, because the isolation of any organism indicates bladder bacteriuria. In addition, urine collected in this way can be kept at 4°C. or at room temperature for up to 10 days before it is cultured.     

Probiotic Therapy: Immunomodulating Approach Toward Urinary Tract Infection

Urinary tract infection (UTI) is an extremely common health problem, with an unpredictable history. Members of enterobacteriaceae family such as Escherichia coli, which are normal inhabitants of human intestines, account for the majority of these uncomplicated infections. Rarely, UTI can result from virus or fungus. There is a close correlation between loss of the normal genital microbiota, particularly Lactobacillus species, and an increased incidence of genital and bladder infections. Although antimicrobial agents are generally effective in eradicating these infections, there is a high incidence of recurrence. Use of Lactobacillus species to combat UTI is now giving modern concept of modern genitourinary vaccine with the facts that it not only maintains low pH of the genital area, produces hydrogen peroxide and hinders the growth of E. coli but also activates Toll-like receptor-2 (TLR2), which produces interleukin-10 (IL-10) and myeloid differentiation factor 88 (MyD88). E. coli activates TLR4, which is responsible for the activation of IL-12, extracellular signal–regulated kinase (ERK) and c-Jun N-terminal kinase (JNK). This process downregulates inflammatory reactions caused due to pathogens. Current review covers the probiotics-based TLR therapy and shed some knowledge for the use of Lactobacillus species as probiotics.