Comparative effectiveness of azithromycin for treating scrub typhus: A PRISMA-compliant systematic review and meta-analysis

Open-labeled Randomized Controlled Trial on Efficacy of Azithromycin Versus Doxycycline in Pediatric Scrub Typhus

BACKGROUND

Doxycycline (DX) is the first-line therapeutic agent for scrub typhus. Macrolides, especially azithromycin (AZ), have been found to be equally efficacious as DX for treating scrub typhus in adults. We conducted this study to compare the efficacy of AZ versus DX in pediatric scrub typhus.

STUDY DESIGN

Open-label randomized controlled trial.

METHODS

Children 1-14 years of age suffering from acute febrile illness of ≥5 days and with a positive scrub IgM serology were randomized to receive either DX (2.2 mg/kg/dose twice daily in <40 kg; 100 mg BD in >40 kg for 7 days) or AZ (10 mg/kg/day for 5 days). The primary outcome was defervescence within 7 days of DX or 5 days of AZ.

RESULTS

We had 75 children randomized and analyzed using an intention-to-treat approach and 60 children analyzed via per-protocol analysis. The proportion of children achieving defervescence was comparable in 2 groups [per-protocol analysis: 90.9% in the DX group vs. 96.3% in the AZ group, RR: 0.94 (95% CI: 0.83-1.08)]. On Kaplan-Meier curves, AZ showed a significantly higher probability of defervescence at any time point during treatment as compared with DX (log-rank test P value 0.035).

CONCLUSION

AZ and DX had comparable rates of defervescence among children with scrub typhus. Trial registration No.: CTRI/2020/01/022991.

Macrolides versus other antibiotics in pediatric scrub typhus: A meta-analysis

BACKGROUND

While Doxycycline is the recommended drug for treating scrub typhus, there is a growing trend of using Macrolides and Other antibiotics due to their perceived advantages. In this study, we compared the efficacy of Macrolides versus Other antibiotics in the treatment of pediatric scrub typhus.

METHODS

Meta-analysis of randomized controlled trials (RCTs) with GRADE (Grading of Recommendations, Assessment, Development and Evaluation) application. Major databases were searched till 30th December 2022. Children of all age groups were included. Primary outcomes included mortality rate and time to defervescence (h).

RESULTS

Of the 103 citations retrieved, 5 trials, including 383 children up to 15 years of age with probable and confirmed cases of scrub typhus, were included. None of the trials reported mortality rate. The pooled results from the trials found no significant difference between Azithromycin and Other antibiotics for any of the outcome measures. The certainty of evidence for the primary outcome was deemed to be of "very low certainty", while the certainty of evidence for the secondary outcomes ranged from "low to moderate certainty".

CONCLUSIONS

The current meta-analysis revealed that there was no significant difference between Azithromycin and Other antibiotics (such as Doxycycline and Chloramphenicol) in the treatment of scrub typhus in children. However, it's important to note that the evidence generated for the primary outcome was of "very low certainty".

PROSPERO REGISTRATION NUMBER

CRD42021276577.

Intravenous Doxycycline, Azithromycin, or Both for Severe Scrub Typhus

BACKGROUND

The appropriate antibiotic treatment for severe scrub typhus, a neglected but widespread reemerging zoonotic infection, is unclear.

METHODS

In this multicenter, double-blind, randomized, controlled trial, we compared the efficacy of intravenous doxycycline, azithromycin, or a combination of both in treating severe scrub typhus. Patients who were 15 years of age or older with severe scrub typhus with at least one organ involvement were enrolled. The patients were assigned to receive a 7-day course of intravenous doxycycline, azithromycin, or both (combination therapy). The primary outcome was a composite of death from any cause at day 28, persistent complications at day 7, and persistent fever at day 5.

RESULTS

Among 794 patients (median age, 48 years) who were included in the modified intention-to-treat analysis, complications included those that were respiratory (in 62%), hepatic (in 54%), cardiovascular (in 42%), renal (in 30%), and neurologic (in 20%). The use of combination therapy resulted in a lower incidence of the composite primary outcome than the use of doxycycline (33% and 47%, respectively), for a risk difference of -13.3 percentage points (95% confidence interval [CI], -21.6 to -5.1; P = 0.002). The incidence with combination therapy was also lower than that with azithromycin (48%), for a risk difference of -14.8 percentage points (95% CI, -23.1 to -6.5; P<0.001). No significant difference was seen between the azithromycin and doxycycline groups (risk difference, 1.5 percentage points; 95% CI, -7.0 to 10.0; P = 0.73). The results in the per-protocol analysis were similar to those in the primary analysis. Adverse events and 28-day mortality were similar in the three groups.

CONCLUSIONS

Combination therapy with intravenous doxycycline and azithromycin was a better therapeutic option for the treatment of severe scrub typhus than monotherapy with either drug alone. (Funded by the India Alliance and Wellcome Trust; INTREST Clinical Trials Registry-India number, CTRI/2018/08/015159.).

Treatment outcomes of oral doxycycline versus intravenous azithromycin in adults hospitalized with scrub typhus: A retrospective study using inverse probability treatment weighting (IPTW) propensity analysis

OBJECTIVE

Only a few well-designed studies that have investigated the effectiveness of azithromycin in treating adult patients hospitalized with scrub typhus are currently available. The purpose of our study was to compare the effects of intravenous azithromycin administration with those of oral doxycycline, and to evaluate cardiovascular death associated with intravenous azithromycin in adult patients hospitalized with scrub typhus.

METHODS

This retrospective study investigated Korean National Infectious Disease Cohort Collaborative-registered scrub typhus-infected patients who were hospitalized between January 1, 2013, and December 31, 2021, and who were ≥18 years old. The primary outcome was time to fever clearance and the secondary outcomes were treatment failure, relapse, scrub typhus-related death, or azithromycin-related cardiovascular death. To address any indication bias, inverse probability of treatment weighting (IPTW) analysis was performed. Times to fever clearance between the doxycycline and azithromycin groups were compared using log-rank tests and Kaplan-Meier curves.

RESULTS

A total of 326 consecutive patients with laboratory-confirmed scrub typhus were included in this study of whom 109 were treated with azithromycin and 217 with doxycycline. Using IPTW, there were no statistically significant differences in the following end points between the azithromycin and doxycycline groups: median time to fever clearance (3 days vs. 3 days, P = 0.649), treatment failure (0.71% vs. 0.42%, P = 0.702), relapse (0.0% vs. 0.0%), and scrub typhus-related death (5.12% vs. 0.0%, P = 0.155). No azithromycin-related cardiovascular deaths occurred. In the sensitivity analyses, there were no significant changes in effect size.

CONCLUSIONS

Our study showed that the therapeutic effects and safety of intravenous azithromycin are comparable to those of oral doxycycline administration in patients hospitalized with scrub typhus. A well-designed randomized controlled trial may help further evaluate the most adequate route of administration, dose and duration of treatment with azithromycin.

Evaluation of the Therapeutic Effect of Antibiotics on Scrub Typhus: A Systematic Review and Network Meta-Analysis

Background

To explore the efficacy and safety of drugs in patients with scrub typhus.

Methods

For this systematic review and network meta-analysis, we searched PubMed, Embase, Web of Science, Cochrane Central Register of Clinical Trials, China National Knowledge Infrastructure (CNKI), and Wanfang data (WF) up to December 2021. All randomized controlled trials (RCTs) of antibiotics used to treat scrub typhus were included without language or date restrictions. The overall effectiveness was evaluated from 4 perspectives: cure rate (CR), defervescence time (DT), gastrointestinal symptoms–adverse events (GS-AD), and abnormal blood count–adverse events (ABC-AD). The quality of evidence was evaluated using the Cochrane Risk of Bias tool and GRADE system.

Results

Sixteen studies involving 1,582 patients were included to evaluate 7 drugs, namely, azithromycin, doxycycline, chloramphenicol, tetracycline, rifampin, moxifloxacin, and telithromycin. In this network meta-analysis, rifampicin (82%) and chloramphenicol (65%) were more effective in terms of CR, and moxifloxacin (3%) from the quinolone family was the worst. Azithromycin caused the fewest events in terms of ABC-AD. No differences were found in this network meta-analysis (NMA) in terms of DT and GS-AD.

Conclusions

Rifampicin was associated with the highest CR benefit and the lowest risk of DT when used to treat patients with scrub typhus, except in areas where tuberculosis (TB) was endemic. Azithromycin was found to be better in CR and was associated with a lower probability of GS-AD and ABC-AD; therefore, it may be considered to treat pregnant women and children. Moxifloxacin had a much lower CR than other drugs and is, therefore, not recommended for the management of scrub typhus.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/, identifier: CRD42021287837.

Oral Azithromycin Versus Doxycycline in the Treatment of Children With Uncomplicated Scrub Typhus: A Randomized Controlled Trial

OBJECTIVES

To compare the efficacy of azithromycin versus doxycycline in treatment of children with uncomplicated scrub typhus in terms of percentage of children who attained remission of fever after 72 hours of administration of first dose of the study drug, mean time taken to attain fever defervescence, normalization of laboratory parameters, resolution of hepatosplenomegaly and lymphadenopathy.

DESIGN

Interventional, open-labeled randomized controlled trial.

STUDY METHODS

Patients admitted with undifferentiated fever in the In-Patient Department (IPD), Department of Paediatrics, All India Institute of Medical Sciences, Bhubaneswar, India, as per the inclusion criteria were randomized and was treated with azithromycin at 10 mg/kg/d in one group and doxycycline at 4.4 mg/kg/d for 5 days in the other group and was assessed based on the primary and secondary objectives.

RESULTS

There was no statistically significant difference between the percentage of children who attained remission of fever after 72 hours of administration of azithromycin (98.2%) and doxycycline (96.5%) (P value 0.47) and the average time taken for fever defervescence (azithromycin: 24.53 hours; doxycycline: 25.82 hours; P value 0.36). The odds of attaining fever remission in the doxycycline group as compared with the azithromycin group was 1.01 (95% confidence interval -0.60 to -1.71), which was also statistically not significant. There was less incidence of adverse drug events in the azithromycin group (1.78%) as compared with the doxycycline group (8.6%), which was statistically significant (P value 0.02).

CONCLUSION

Azithromycin is equally efficacious in terms of fever defervescence, resolution of clinical signs and laboratory parameters as doxycycline, is safer and better tolerated in children.

Massive Tick Bites Causing Spotted Fever Rickettsial Infection: A Hazard in a Tea Plantation, Sri Lanka

Tea plantations in Sri Lanka cover the central hills of the island, where spotted fever group (SFG) rickettsial infection is common. In most cases, the history of tick bite is obscure and eschars are not present. A 45-y-old female experienced massive tick bites while working in her tea plantation. She developed fever 2 d after exposure, but the diagnosis of SFG infection was not considered until a skin rash appeared on the eighth day. She had a very high titer of antirickettsial antibodies detected by immunofluorescence assay and responded to doxycycline. Here, we highlight the high risk of exposure to ticks and tick bites within tea estates and its causal relationship to SFG infection, which is increasing in Sri Lanka. Active case detection, notification, surveillance, and community awareness are imperative. Possible preventative measures for tick bites have to be introduced. There is a need to explore the effectiveness of local remedies currently in use.

Antibiotic Response to Pediatric Scrub Typhus in South India: Is Clinical Failure to Azithromycin to be Worried?

BACKGROUND

Scrub typhus is typically associated with a rapid defervescence and clinical improvement within 48 h of initiation of appropriate antibiotics. But increasing reports of resistance to anti-rickettsial medications in scrub typhus are being reported in the literature.

METHODS

This is a retrospective observational study of children up to the age of 14 years admitted between July 2017 and March 2020, to a private medical college hospital in southern part of India. The aim of this study was to compare the clinical response to antibiotic therapy with doxycycline and azithromycin in pediatric scrub typhus infection.

RESULTS

One hundred thirty-eight children with scrub typhus infection were included for analysis. The median fever control time (h) was 12 (IQR = 6-29) and 24 (IQR = 10-52) with doxycycline and azithromycin respectively (p < 0.001*). Rapid fever control within 48 h was observed in 92% with doxycycline and in 74% with azithromycin (p < 0.001*). The clinical failure rate (defined by the necessity to change the antibiotics due to: (i) worsening of symptoms and signs of scrub typhus despite 48 h of antibiotics or (ii) persistence of fever and other symptoms of scrub typhus beyond 72 h), was significantly less with doxycycline (1%) compared with azithromycin (9.6%).

CONCLUSION

There has been a significant delayed clinical response to azithromycin in the treatment of scrub typhus in India, when compared to doxycycline. Hence it is preferable to use doxycycline as the first line of antibiotic for undifferentiated fever in scrub typhus endemic areas.

LAY SUMMARY

This retrospective study aims to compare the clinical response to doxycycline or azithromycin in the treatment of scrub typhus infection in children. The median fever control time, clinical failure rate and the proportion of children with rapid defervescence of fever within 48 h were significantly superior with doxycycline as compared to azithromycin. The findings of this study and those of similar studies in India represent a spectrum of delayed clinical response of Orientia tsutsugamushi to azithromycin as compared to doxycycline in this region.

Scrub Typhus and Other Rickettsial Infections

Scrub typhus and other rickettsial infections contribute to 25 - 50% of acute undifferentiated febrile illnesses in endemic regions. Delayed recognition and therapy increase the morbidity and mortality. The constellation of fever with eschar or rash and multisystem involvement should facilitate the diagnosis and initiation of appropriate therapy. The pathological hallmark of rickettsial infections is endothelial infection and inflammation causing vasculitis. Endothelial inflammation results in microvascular dysfunction and increased vascular permeability. Immune and endothelial activation may worsen microvascular dysfunction, predisposing to multi-organ failure. Serology is the mainstay of diagnosis, although false negatives occur early in the disease. Point-of-care rapid diagnostic tests and molecular techniques, such as quantitative polymerase chain reaction (qPCR), can hasten diagnostic processes. Intravenous doxycycline with a loading dose is the most widely used antibiotic in critically ill patients, with azithromycin as a suitable alternative. Early appropriate treatment and organ support can decrease the duration of illness and be life-saving. How to cite this article: Gunasekaran K, Bal D, Varghese GM, et al. Scrub Typhus and Other Rickettsial Infections. Indian J Crit Care Med 2021;25(Suppl 2):S138-S143.

Efficacy and Safety of Antibiotics for Treatment of Scrub Typhus: A Network Meta-analysis

IMPORTANCE

Antibiotics have been used for many years to treat scrub typhus, but their efficacy and safety have not been studied thoroughly.

OBJECTIVE

To compare and rank different antibiotics to identify which one can safely eliminate Orientia tsutsugamushi and efficiently alleviate fever in patients with scrub typhus.

DATA SOURCES

An electronic search of PubMed and Embase was conducted, from database inception to July 12, 2019. The study was conducted from July 12 to September 2, 2019.

STUDY SELECTION

Randomized clinical trials and retrospective studies that evaluated the use of antibiotics for treatment in patients diagnosed with scrub typhus caused by O tsutsugamushi were included. Records of articles in English were considered eligible. Studies were assessed independently by 2 reviewers, with disagreement resolved by consensus. Of 6408 studies initially identified, 10 randomized clinical trials and 4 retrospective study met the criteria for further analysis.

DATA EXTRACTION AND SYNTHESIS

This study followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses extension statement for systematic reviews incorporating network meta-analyses of health care interventions. Data were independently extracted by 2 reviewers and synthesized with frequentist random-effects network meta-analyses.

MAIN OUTCOMES AND MEASURES

The primary outcome was efficacy of the antibiotic, considered as the number of patients who achieved complete healing with an antibiotic. Safety, defined as the prevalence of adverse events associated with the antibiotics, was the secondary outcome, and defervescence time was the tertiary outcome. P scores (scale of 0 to 1, with 1 indicating superiority to other treatments) were used to rank the efficacy, safety, and defeverescence time of the antibiotics.

RESULTS

Three searches for articles in Embase and PubMed identified 10 randomized clinical trials (888 participants) and 4 retrospective studies (323 participants) for further analyses. No particular treatment regimen showed a significant advantage or disadvantage with regard to efficacy or safety. However, meta-analysis of retrospective studies indicated that clarithromycin (P score = 0.8730) alleviated fever more efficiently than other antibiotics.

CONCLUSIONS AND RELEVANCE

No treatment regimen reported in this network meta-analysis showed a significant advantage or disadvantage with regard to efficacy or safety. However, clarithromycin might be a better choice than the other drugs for alleviating fever.

The epidemiology and clinical features of rickettsial diseases in North Queensland, Australia: Implications for patient identification and management

Background

Rickettsial infections are a common cause of hospitalization in tropical settings, although early diagnosis is challenging in the rural locations where these infections are usually seen.

Methods

This retrospective, clinical audit of microbiologically-confirmed cases of scrub typhus or spotted fever group (SFG) rickettsial infection between 1997 and 2016 was performed a tertiary referral hospital in tropical Australia. Clinical, laboratory and radiological findings at presentation were correlated with the patients’ subsequent clinical course.

Results

There were 135 locally-acquired cases (95 scrub typhus, 37 SFG, 3 undifferentiated). There were nine hospitalizations during the first 5 years of the study period and 81 in the last 5 years (p for trend = 0.003). Eighteen (13%) of the 135 cases required ICU admission, all of whom were adults. A greater proportion of patients with SFG infection required ICU support (8/37 (22%) compared with 10/95 (11%) scrub typhus cases), although this difference did not reach statistical significance (p = 0.10). Three (8%) of the 37 patients with SFG infection had severe disease (1 died, 2 developed permanent disability) versus 0/95 scrub typhus patients (p = 0.02). Adults with a high admission qSOFA score (≥2) had an odds ratio (OR) of 19 (95% CI:4.8–74.5) for subsequent ICU admission (p<0.001); adults with a high NEWS2 score (≥7) had an OR of 14.3 (95% CI:4.5–45.32) for ICU admission (p<0.001). A patient’s respiratory rate at presentation had strong prognostic utility: if an adult had an admission respiratory rate <22 breaths/minute, the negative predictive value for subsequent ICU admission was 95% (95% CI 88–99).

Conclusions

In the well-resourced Australian health system outcomes are excellent, but the local burden of rickettsial disease appears to be increasing and the clinical phenotype of SFG infections may be more severe than previously believed. Simple, clinical assessment on admission has prognostic utility and may be used to guide management.

Rickettsial infections are a common cause of hospitalization in tropical settings, although early, definitive diagnosis is challenging in the rural and remote locations where they are usually seen. It is important to recognise rickettsial infections early in their disease course as they can lead to life-threatening multi-organ failure if specific anti-rickettsial antimicrobial therapy is not prescribed promptly. In tropical Australia, scrub typhus and spotted fever group (SFG) rickettsiae are the dominant rickettsial pathogens and this twenty-year retrospective series examines the clinical and laboratory findings which might facilitate their recognition. The study highlights the infections’ increasing local clinical burden and reports that over 20% of the SFG cases in the series required Intensive Care Unit (ICU) admission, suggesting that severe SFG disease may be more common than previously believed. Simple, clinical prediction scores—calculated at presentation—identified patients who would subsequently require ICU admission. Importantly, they were also able to identify patients at low risk of disease progression. These entirely clinical scores—which can be calculated rapidly at the bedside—have the potential to facilitate the management of patients with scrub typhus and SFG infection, particularly in resource-limited settings which have the greatest burden of disease.

A review of the global epidemiology of scrub typhus

Scrub typhus is a serious public health problem in the Asia-Pacific area. It threatens one billion people globally, and causes illness in one million people each year. Caused by Orientia tsutsugamushi, scrub typhus can result in severe multiorgan failure with a case fatality rate up to 70% without appropriate treatment. The antigenic heterogeneity of O. tsutsugamushi precludes generic immunity and allows reinfection. As a neglected disease, there is still a large gap in our knowledge of the disease, as evidenced by the sporadic epidemiologic data and other related public health information regarding scrub typhus in its endemic areas. Our objective is to provide a systematic analysis of current epidemiology, prevention and control of scrub typhus in its long-standing endemic areas and recently recognized foci of infection.