OBJECTIVES: To assess and compare the effects of different antibiotic regimens for treatment of scrub typhus.

SEARCH METHODS: We searched the following databases up to 8 January 2018: the Cochrane Infectious Diseases Group specialized trials register; CENTRAL, in the Cochrane Library (2018, Issue 1); MEDLINE; Embase; LILACS; and the metaRegister of Controlled Trials (mRCT). We checked references and contacted study authors for additional data. We applied no language or date restrictions.

SELECTION CRITERIA: Randomized controlled trials (RCTs) or quasi-RCTs comparing antibiotic regimens in people with the diagnosis of scrub typhus based on clinical symptoms and compatible laboratory tests (excluding the Weil-Felix test).

DATA COLLECTION AND ANALYSIS: For this update, two review authors re-extracted all data and assessed the certainty of evidence. We meta-analysed data to calculate risk ratios (RRs) for dichotomous outcomes when appropriate, and elsewhere tabulated data to facilitate narrative analysis.

MAIN RESULTS: We included six RCTs and one quasi-RCT with 548 participants; they took place in the Asia-Pacific region: Korea (three trials), Malaysia (one trial), and Thailand (three trials). Only one trial included children younger than 15 years (N = 57). We judged five trials to be at high risk of performance and detection bias owing to inadequate blinding. Trials were heterogenous in terms of dosing of interventions and outcome measures. Across trials, treatment failure rates were low.Two trials compared doxycycline to tetracycline. For treatment failure, the difference between doxycycline and tetracycline is uncertain (very low-certainty evidence). Doxycycline compared to tetracycline may make little or no difference in resolution of fever within 48 hours (risk ratio (RR) 1.14, 95% confidence interval (CI) 0.90 to 1.44, 55 participants; one trial; low-certainty evidence) and in time to defervescence (116 participants; one trial; low-certainty evidence). We were unable to extract data for other outcomes.Three trials compared doxycycline versus macrolides. For most outcomes, including treatment failure, resolution of fever within 48 hours, time to defervescence, and serious adverse events, we are uncertain whether study results show a difference between doxycycline and macrolides (very low-certainty evidence). Macrolides compared to doxycycline may make little or no difference in the proportion of patients with resolution of fever within five days (RR 1.05, 95% CI 0.99 to 1.10; 185 participants; two trials; low-certainty evidence). Another trial compared azithromycin versus doxycycline or chloramphenicol in children, but we were not able to disaggregate date for the doxycycline/chloramphenicol group.One trial compared doxycycline versus rifampicin. For all outcomes, we are uncertain whether study results show a difference between doxycycline and rifampicin (very low-certainty evidence). Of note, this trial deviated from the protocol after three out of eight patients who had received doxycycline and rifampicin combination therapy experienced treatment failure.Across trials, mild gastrointestinal side effects appeared to be more common with doxycycline than with comparator drugs.

METHODS: We did a systematic review and meta-analysis of primary antibiotic resistance to H pylori and the efficacy of first-line regimens in the Asia-Pacific region. We searched PubMed, Embase, and the Cochrane Library for articles published between Jan 1, 1990, and Sept 30, 2016; we also searched abstracts from international conferences. Both observational studies and randomised controlled trials were eligible for inclusion in the analysis of primary antibiotic resistance, but only randomised controlled trials were eligible for inclusion in the analysis of efficacy of first-line therapies. Meta-analysis was by the random-effects model to account for the substantial variations in resistance across the region. We did subgroup analyses by country and study period (ie, before 2000, 2001-05, 2006-10, and 2011-15) to establish country-specific prevalences of primary antibiotic resistance and first-line eradication rates. This study is registered with PROSPERO, number CRD42017057905.

FINDINGS: 176 articles from 24 countries were included in our analysis of antibiotic resistance. The overall mean prevalences of primary H pylori resistance were 17% (95% CI 15-18) for clarithromycin, 44% (95% CI 39-48) for metronidazole, 18% (95% CI 15-22) for levofloxacin, 3% (95% CI 2-5) for amoxicillin, and 4% (95% CI 2-5) for tetracycline. Prevalence of resistance to clarithromycin and levofloxacin rose significantly over time during the period investigated, whereas resistance to other antibiotics remained stable. 170 articles from 16 countries were included in analysis of efficacy of first-line therapies. We noted unsatisfactory efficacy (ie, <80%) with clarithromycin-containing regimens in countries where the clarithromycin resistance rates were higher than 20%.

INTERPRETATION: The prevalence of primary antibiotic resistance varied greatly among countries in the Asia-Pacific region, and thus treatment strategy should be adapted relative to country-specific resistance patterns. Clarithromycin-containing regimens should be avoided in countries where the prevalence of clarithromycin resistance is higher than 20%.