Benefits and harms of screening for and treatment of asymptomatic bacteriuria in pregnancy: a systematic review

Abstract

BackgroundMost European and North American clinical practice guidelines recommend screening for asymptomatic bacteriuria (ASB) as a routine pregnancy test. Antibiotic treatment of ASB in pregnant women is supposed to reduce maternal upper urinary tract infections (upper UTIs) and preterm labour. However, most studies supporting the treatment of ASB were conducted in the 1950s to 1980s. Because of subsequent changes in treatment options for ASB and UTI, the applicability of findings from these studies has come into question. Our systematic review had three objectives: firstly, to assess the patient-relevant benefits and harms of screening for ASB versus no screening; secondly, to compare the benefits and harms of different screening strategies; and thirdly, in case no reliable evidence on the overarching screening question was identified, to determine the benefits and harms of treatment of ASB.MethodsWe systematically searched several bibliographic databases, trial registries, and other sources (up to 02/2016) for randomised controlled trials (RCTs) and prospective non-randomised trials. Two authors independently reviewed abstracts and full-text articles and assessed the risk of bias of the studies included. As meta-analyses were not possible, we summarised the results qualitatively.ResultsWe did not identify any eligible studies that investigated the benefits and harms of screening for ASB versus no screening or that compared different screening strategies. We identified four RCTs comparing antibiotics with no treatment or placebo in 454 pregnant women with ASB. The results of 2 studies published in the 1960s showed a statistically significant reduction in rates of pyelonephritis (odds ratio [OR] = 0.21, 95 % confidence interval [CI] 0.07–0.59) and lower UTI (OR = 0.10, 95 % CI 0.03–0.35) in women treated with antibiotics. By contrast, event rates reported by a recent study were not statistically significantly different, neither regarding pyelonephritis (0 % vs. 2.2 %; OR = 0.37, CI 0.01–9.25, p = 0.515) nor regarding lower UTI during pregnancy (10 % vs. 18 %; Peto odds ratio [POR] = 0.53, CI 0.16–1.79, p = 0.357). Data were insufficient to determine the risk of harms. As three of the four studies were conducted several decades ago and have serious methodological shortcomings, the applicability of their findings to current health care settings is likely to be low. The recent high-quality RCT was stopped early due to a very low number of primary outcome events, a composite of preterm delivery and pyelonephritis. Therefore, the results did not show a benefit of treating ASB.ConclusionsTo date, no reliable evidence supports routine screening for ASB in pregnant women.Electronic supplementary materialThe online version of this article (doi:10.1186/s12884-016-1128-0) contains supplementary material, which is available to authorized users.

Bacteriúria assintomática na gravidez de baixo risco – qual a evidência do seu tratamento?

“…De acordo com os autores, a proporção de grávidas com pielonefrite, parto prematuro, ou ambos não diferiu entre as grávidas com BUA não tratadas ou tratadas com placebo e as grávidas sem BUA (6 [2,9%] de 208 versus 77 [1,9%] de 4035, razão de chances ajustada [OR] = 1,5; IC 95% 0,6-3,5) ou entre as grávidas com BUA tratadas com nitrofurantoína versus aquelas que não foram tratadas ou receberam placebo (1 [2,5%] de 40 vs. 6 [2,9%] de 208, diferença de risco = 0,4, IC 95% 3,6-9,4). As grávidas com BUA não tratadas e tratadas com placebo desenvolveram pielonefrite em cinco (2,4%) de 208 casos, em comparação com 24 (0,6%) de 4035 grávidas sem BUA (OR ajustado 9,9%, IC 95% 1, [4][5][6][7][8][9][10][11]4).…”

“…Concluem ainda que a redução do baixo peso ao nascer e parto prematuro com tratamento antibiótico é consistente com as teorias sobre o papel da infeção nos desfechos adversos da gravidez, mas afirmam que essa associação deve ser interpretada com cautela, dada a qualidade muito pobre dos estudos incluídos. Deste modo, tendo em conta que as conclusões desta revisão sistemática foram baseadas em estudos com importantes limitações metodológicas, sendo apesar de tudo orientados para o doente, atribuímos a este artigo um nível de evidência 2.Angelescu et al9 , em 2016, realizaram uma revisão sistemática tendo por objetivos avaliar os benefícios relevantes para o doente e os malefícios do rastreio da bacteriúria assintomática versus nenhum rastreio, comparar os benefícios e malefícios de diferentes estratégias de rastreio, e determinar os benefícios e malefícios do tratamento da bacteriúria assintomática. Dois revisores avaliaram independentemente os artigos para inclusão e o risco de viés.…”

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“…Antibiotics must therefore be given only when required and with adequate patient education on importance of compliance because failure to take antibiotic for the full period recommended also causes resistance [30]. Effective ASB treatment during pregnancy is expected to reduce risk of pyelonephritis and adverse birth outcomes including preterm birth and low birth weight [2,5]. Treatment and clearance of bacteria in the pregnant women requires that sensitive antibiotics be identified by culture sensitivity test where possible [6][7][8][9][10][11][12][13][14][15].…”

“…Several international and national guidelines recommend screening and treatment of ASB to reduce risk of pyelonephritis [6]. Several antibiotics are available for selection for treatment of ASB in pregnancy including, amoxil, ampicillin, cephasporin, nitrofurantoin, trimethoprim and sulfamethoxazole [2]. Treatment of ASB with antibiotics in pregnancy aims to clear the infection, which is only possible if the isolated bacterium is susceptible to it [6].…”

“…ASB is defined as growth of more than 100 000 colony forming units per millilitre (cfu/ ml) in culture of midstream urine obtained from an individual without signs and symptoms of asymptomatic bacteriuria [1,2]. ASB prevalence generally ranges from 2% to 10% [3].…”