Ciprofloxacin for the treatment of cholera: a randomized, double-blind, controlled clinical trial of a single daily dose in Peruvian adults

Screening of Potential Vibrio cholerae Bacteriophages for Cholera Therapy: A Comparative Genomic Approach

Cholera continues to be a major burden for developing nations, especially where sanitation, quality of water supply, and hospitalization have remained an issue. Recently, growing antimicrobial-resistant strains of Vibrio cholerae underscores alternative therapeutic strategies for cholera. Bacteriophage therapy is considered one of the best alternatives for antibiotic treatment. For the identification of potential therapeutic phages for cholera, we have introduced a comprehensive comparative analysis of whole-genome sequences of 86 Vibrio cholerae phages. We have witnessed extensive variation in genome size (ranging from 33 to 148 kbp), GC (G + C) content (varies from 34.5 to 50.8%), and the number of proteins (ranging from 15 to 232). We have identified nine clusters and three singletons using BLASTn, confirmed by nucleotide dot plot and sequence identity. A high degree of sequence and functional similarities in both the genomic and proteomic levels have been observed within the clusters. Evolutionary analysis confirms that phages are conserved within the clusters but diverse between the clusters. For each therapeutic phage, the top 2 closest phages have been identified using a system biology approach and proposed as potential therapeutic phages for cholera. This method can be applied for the classification of the newly isolated Vibrio cholerae phage. Furthermore, this systematic approach might be useful as a model for screening potential therapeutic phages for other bacterial diseases.

Efficacy of Ciprofloxacin for Treatment of Cholera Associated with Diminished Susceptibility to Ciprofloxacin to Vibrio cholerae O1

Objective

We identified a poor clinical response to treatment of cholera with a single 1 g dose of ciprofloxacin, a standard treatment for cholera.

Methods

To determine reasons for the poor response and better therapeutic approaches we examined the minimal inhibitor concentration (MIC, n = 275) and disc-diffusion zone sizes (n = 205) for ciprofloxacin and nalidixic acid of V. cholerae O1 strains isolated in Bangladesh from 1994 to 2012, and reexamined data from 161patients infected with Vibrio cholerae O1 recruited in four clinical trials who received single- or multiple-dose ciprofloxacin for treatment of cholera and compared their clinical response to the V. cholerae O1 susceptibility.

Results

Although all 275 isolates of V. cholerae O1 remained susceptible to ciprofloxacin using standard MIC and disc-diffusion thresholds, the MIC⁹⁰ to ciprofloxacin increased from 0.010 in 1994 to 0.475 μgm/ml in 2012. Isolates became frankly resistant to nalidixic with the MIC⁹⁰ increasing from 21 μgm/ml in 1994 to >256 μgm/ml and 166 of 205 isolates from 1994 to 2005 being frankly resistant using disc-diffusion testing. Isolates resistant to nalidixic acid by disc-diffusion testing had a median ciprofloxacin MIC of 0.190 μgm/ml (10^th-90^th centiles 0.022 to 0.380); nalidixic acid-susceptible isolates had a median ciprofloxacin MIC of 0.002 (0.002 to 0.012).The rate of clinical success with single-dose ciprofloxacin treatment for nalidixic acid-susceptible strains was 94% (61 of 65 patients) and bacteriologic success 97% (63/65) compared to 18% (12/67) and 8% (5/67) respectively with nalidixic acid-resistant strains (P<0.001 for both comparisons). Multiple-dose treatment with ciprofloxacin had 86% and 100% clinical and bacteriologic success rates respectively in patients infected with nalidixic acid-susceptible strains of V. cholerae O1 compared to clinical success 67% and bacteriologic success 60% with nalidixic acid-resistant strains.

Conclusions

Single-dose ciprofloxacin is not effective for treating cholera caused by V. cholerae O1 with diminished susceptibility to ciprofloxacin, and nalidixic acid disc-diffusion testing effectively screens for such isolates.

Antimicrobial drugs for treating cholera

BACKGROUND

Cholera is an acute watery diarrhoea caused by infection with the bacterium Vibrio cholerae, which if severe can cause rapid dehydration and death. Effective management requires early diagnosis and rehydration using oral rehydration salts or intravenous fluids. In this review, we evaluate the additional benefits of treating cholera with antimicrobial drugs.

OBJECTIVES

To quantify the benefit of antimicrobial treatment for patients with cholera, and determine whether there are differences between classes of antimicrobials or dosing schedules.

SEARCH METHODS

We searched the Cochrane Infectious Disease Group Specialized Register; the Cochrane Central Register of Controlled Trials (CENTRAL); PubMed; EMBASE; African Index Medicus; LILACS; Science Citation Index; metaRegister of Controlled Trials; WHO International Clinical Trials Registry Platform; conference proceedings; and reference lists to March 2014.

SELECTION CRITERIA

Randomized and quasi-randomized controlled clinical trials in adults and children with cholera that compared: 1) any antimicrobial treatment with placebo or no treatment; 2) different antimicrobials head-to-head; or 3) different dosing schedules or different durations of treatment with the same antimicrobial.

DATA COLLECTION AND ANALYSIS

Two reviewers independently applied inclusion and exclusion criteria, and extracted data from included trials. Diarrhoea duration and stool volume were defined as primary outcomes. We calculated mean difference (MD) or ratio of means (ROM) for continuous outcomes, with 95% confidence intervals (CI), and pooled data using a random-effects meta-analysis. The quality of evidence was assessed using the GRADE approach.

MAIN RESULTS

Thirty-nine trials were included in this review with 4623 participants. Antimicrobials versus placebo or no treatment Overall, antimicrobial therapy shortened the mean duration of diarrhoea by about a day and a half compared to placebo or no treatment (MD -36.77 hours, 95% CI -43.51 to -30.03, 19 trials, 1013 participants, moderate quality evidence). Antimicrobial therapy also reduced the total stool volume by 50% (ROM 0.5, 95% CI 0.45 to 0.56, 18 trials, 1042 participants, moderate quality evidence) and reduced the amount of rehydration fluids required by 40% (ROM 0.60, 95% CI 0.53 to 0.68, 11 trials, 1201 participants, moderate quality evidence). The mean duration of fecal excretion of vibrios was reduced by almost three days (MD 2.74 days, 95% CI -3.07 to -2.40, 12 trials, 740 participants, moderate quality evidence).There was substantial heterogeneity in the size of these benefits, probably due to differences in the antibiotic used, the trial methods (particularly effective randomization), and the timing of outcome assessment. The benefits of antibiotics were seen both in trials recruiting only patients with severe dehydration and in those recruiting patients with mixed levels of dehydration. Comparisons of antimicrobials In head-to-head comparisons, there were no differences detected in diarrhoea duration or stool volume for tetracycline compared to doxycycline (three trials, 230 participants, very low quality evidence); or tetracycline compared to ciprofloxacin or norfloxacin (three trials, 259 participants, moderate quality evidence). In indirect comparisons with substantially more trials, tetracycline appeared to have larger benefits than doxycycline, norfloxacin and trimethoprim-sulfamethoxazole for the primary review outcomes.Single dose azithromycin shortened the duration of diarrhoea by over a day compared to ciprofloxacin (MD -32.43, 95% CI -62.90 to -1.95, two trials, 375 participants, moderate quality evidence) and by half a day compared to erythromycin (MD -12.05, 95% CI -22.02 to -2.08, two trials, 179 participants, moderate quality evidence). It was not compared with tetracycline.

AUTHORS' CONCLUSIONS

In treating cholera, antimicrobials result in substantial improvements in clinical and microbiological outcomes, with similar effects observed in severely and non-severely ill patients. Azithromycin and tetracycline may have some advantages over other antibiotics.

Comparative analysis of different oral approaches to treat Vibrio cholerae infection in adult mice

In this study, we have established an oral phage cocktail therapy in adult mice model and also performed a comparative analysis between phage cocktail, antibiotic and oral rehydration treatment for orally developed Vibrio cholerae infection. Four groups of mice were orally infected with Vibrio cholerae MAK 757 strain. Phage cocktail and antibiotic treated groups received 1×10(8) plaque forming unit/ml (once a daily) and 40mg/kg (once a daily) as an oral dose respectively for consecutive three days after bacterial infection. In case of oral rehydration group, the solution was supplied after bacterial infection mixed with the drinking water. To evaluate the better and safer approach of treatment, tissue and serum samples were collected. Here, phage cocktail treated mice reduced the log10 numbers of colony per gram by 3log10 (p<0.05); however, ciprofloxacin treated mice reduced the viable numbers up to 5log10 (p<0.05). Whereas, the oral rehydration solution application was not able to reduce the viable bacterial count but the disease progress was much more diminished (p>0.05). Besides, it was evident that antibiotic and phage cocktail treated group had a gradual decrease in both IL-6 and TNF-α level for 3 days (p<0.05) but the scenario was totally opposite in bacterial control and oral hydration treated group. Histological examinations also endorsed the phage cocktail and ciprofloxacin treatment in mice. Although, in this murine model of cholera ciprofloxacin was found to be a better antimicrobial agent, but from the safety and specificity point of view, a better method of application could fill the bridge and advances the phages as a valuable agent in treating Vibrio cholerae infection.

Oral cholera vaccines: use in clinical practice

Cholera continues to occur globally, particularly in sub-Saharan Africa and Asia. Oral cholera vaccines have been developed and have now been used for several years, primarily in traveller populations. The licensure in the European Union of a killed whole cell cholera vaccine combined with the recombinant B subunit of cholera toxin (rCTB-WC) has stimulated interest in protection against cholera. Because of the similarity between cholera toxin and the heat-labile toxin of Escherichia coli, a cause of travellers' diarrhoea, it has been proposed that the rCTB-WC vaccine may be used against travellers' diarrhoea. An analysis of trials of this vaccine against cholera (serotype O1) shows that for 4-6 months it will protect 61-86% of people living in cholera-endemic regions; lower levels of protection continue for 3 years. Protection wanes rapidly in young children. Because the risk of cholera for most travellers is extremely low, vaccination should be considered only for those working in relief or refugee settings or for those who will be travelling in cholera-epidemic areas and who will be unable to obtain prompt medical care. The vaccine can be expected to prevent 7% or less of cases of travellers' diarrhoea and should not be used for this purpose.

Single-dose ciprofloxacin versus 12-dose erythromycin for childhood cholera: a randomised controlled trial

BACKGROUND

Single-dose ciprofloxacin is effective for the treatment of severe cholera in adults. We assessed whether single-dose ciprofloxacin would be as effective as 3-day, 12-dose erythromycin in achieving clinical cure in children with severe cholera.

METHODS

We did a randomised, open label, controlled trial in children age 2-15 years with V cholerae O1 or O139 present in stool on dark-field microscopy. Children received either a single 20 mg/kg dose of ciprofloxacin (n=90) or 12.5 mg/kg of erythromycin (n=90) every 6 h for 3 days, and remained in hospital for 5 days. The primary outcome was clinical success of treatment, defined as cessation of watery stools within 48 h of start of drug treatment. Analysis was per protocol. This study is registered with the ClinicalTrials.gov Protocol Registration System at http://www.clinicaltrials.gov (registration number NCT 00142272) [corrected]

FINDINGS

Of 180 children randomised 162 completed the study. Treatment was clinically successful in 60% (47/78) of children treated with ciprofloxacin and in 55% (46/84) of those treated with erythromycin (difference 5% [95% CI -10 to 21]). Children receiving ciprofloxacin vomited less often (58%vs 74%; difference 16% [2 to 30]), had fewer stools (15 vs 21; 6 [0 to 9]), and less stool volume (152 vs 196 mL/kg; 43 mL/kg [13 to 87]) than those receiving erythromycin. Bacteriological failure was more common in ciprofloxacin-treated patients (58%vs 30%; 28% [13 to 43]) than erythromycin-treated patients.

INTERPRETATION

Single-dose ciprofloxacin achieves clinical outcomes similar to, or better than, those achieved with 12-dose erythromycin treatment in childhood cholera, but is less effective in eradicating V cholerae from stool.

Severe acute diarrhea

Acute diarrhea is commonly caused by an infection. Severe acute diarrhea warrants immediate medical evaluation and hospitalization. Indications for stool studies include fever; bloody diarrhea; recent travel to an endemic area; recent antibiotics; immunosuppression; and occupational risks, such as food handlers. Noninfectious causes include inflammatory bowel disease, radiation enteritis, and intestinal ischemia. Management of severe acute diarrhea includes intravenous fluid rehydration and empiric antibiotics. Use of antidiarrheal agents is controversial when invasive pathogens are suspected.

An evaluation of current cholera treatment

Cholera, caused by Vibrio cholerae O1 and O139, is characterised by profuse purging of watery stools, and vomiting and dehydration. The mainstay of therapy of cholera patients is rehydration with oral rehydration salt solution or intravenous Ringer's lactate depending upon the degree of dehydration. Antibiotics such as tetracycline, doxycycline, norfloxacin, ciprofloxacin and furazolidone may be used as an adjunct to rehydration therapy for severely purging cholera patients to reduce the rate of stool output. This shortens the duration of hospital stay, stops excretion of vibrios in the stool and minimises the requirement of fluids. Resistance to many of these drugs has been observed and is a matter of concern. Other antidiarrhoeals are not recommended. Many antisecretory drugs have been tried as an adjunct therapy, unfortunately, until today, none has been found useful in the treatment of cholera. Feeding during and after cholera is emphasised.

New developments in the understanding of cholera

Recent advances in prevention and treatment of cholera have occurred in the areas of vaccine testing, modifications of oral-rehydration solutions (ORS), and antimicrobial treatment. Oral vaccines consisting of killed whole bacterial cells (WC) with and without the B-subunit of cholera toxin (BS) were shown to be effective in large trials in Bangladesh, Peru, and Vietnam. However, the trials did not resolve whether two or three doses of vaccine are required and whether BS adds significantly to the immune protection of WC. Live, attenuated bacterial vaccines that are immunogenic and have been shown protective in human volunteer studies are candidates for future field trials. Rehydration of patients is a life- saving effort. The best ORS contains rice powder in place of glucose, and solutions with reduced osmolarity (245 mOsm/L, sodium 75 mEq/L) are as effective as standard ORS. Ciprofloxacin in a single dose is effective in adults, and erythromycin or ampicillin in multiple doses is effective in children.

Epidemiological, clinical and therapeutic evaluation of the Italian cholera epidemic in 1994

In the period between 18 October and 4 December 1994, 12 indigenous cases of cholera were registered in the southern Italian region of Puglia, 10 of them were diagnosed in our Departments of Infectious Diseases. All patients were infected by consumption of raw fish or mussels. The patients had an elevated mean age and most were affected with systemic pathologies. The clinical course was mild and rarely complicated, although frequently the characteristic riziform diarrhoea was absent. In all patients V. cholerae serotype Ogawa biotype El Tor, was isolated; one patient was co-infected by Salmonella typhi. All strains showed resistance to cotrimoxazole and tetracycline. Nine of ten patients were treated with oral ciprofloxacin at 1 g/day for 10 days resulting in disappearance of the symptoms within a median of 36 hours and negative fecal cultures within a median of 24 hours. Our data suggest that Italy is at high risk of infection imported from nearby nations. The resistance to commonly used antibiotics for treatment of cholera and the good response to ciprofloxacin suggest including fluoroquinolones among the drugs of first choice geographical areas involved in the circulation of resistant strains of V. cholerae O1.

Randomised controlled comparison of single-dose ciprofloxacin and doxycycline for cholera caused by Vibrio cholerae 01 or 0139

BACKGROUND

Effective antimicrobial therapy can reduce the duration and volume of cholera diarrhoea by half. However, such treatment is currently limited by Vibrio cholerae resistance to the drugs commonly prescribed for cholera, and by the difficulties involved in the administration of multi-drug doses under field conditions. Because of its favourable pharmacokinetics we thought it likely that single-dose ciprofloxacin would be effective in the treatment of cholera.

METHODS

In this double-blind study treatment was either a single 1 g oral dose of ciprofloxacin plus doxycycline placebo, or a single 300 mg oral dose of doxycycline plus ciprofloxacine placebo. 130 moderately or severely dehydrated men infected with V cholerae 01 and 130 infected with V cholerae 0139 were randomly assigned treatment. Patients stayed in hospital for 5 days. We measured fluid intake and stool volume every 6 h, and a sample of stool for culture was obtained daily. The primary outcome measures were clinical success--the cessation of watery stool within 48 h; and bacteriological success--absence of V cholerae from cultures of stool after study day 2.

FINDINGS

Among patients infected with V cholerae 01, treatment was clinically successful in 62 (94%) of 66 patients who received ciprofloxacin and in 47 (73%) of 64 who receive doxycycline (difference 21% [95% Cl 8-33]); the corresponding proportions with bacteriological success were 63 (95%) and 44 (69%) (27% [14-39]). Among patients infected with V cholerae 0139, treatment was clinically successful in 54 (92%) of 59 patients who received ciprofloxacin and in 65 (92%) of 71 who received doxycycline (< 1% [-9 to 9]), and bacteriologically successful in 58 (98%) and 56 (79%), respectively (19% [9-30]). Total volume of watery stool did not differ significantly between ciprofloxacin-group and doxycycline-group patients infected with either V cholerae 01 or 0139. All but one of the V cholerae 01 and all of the 0139 isolates were susceptible in vitro to doxycycline, whereas 48 (37%) of the V cholerae 01 isolates and none of the 0139 isolates were resistant to tetracycline. Treatment clinically failed in 14 (52%) of 27 doxycycline-treated patients infected with a tetracycline-resistant V cholerae 01 strain, compared with three (8%) of 37 patients infected with a tetracycline-susceptible strain (44% [23-65]).

INTERPRETATION

Single-dose ciprofloxacin is effective in the treatment of cholera caused by V cholerae 01 or 0139 and is better than single-dose doxycycline in the eradication of V cholerae from stool. Single-dose ciprofloxacin may also be the preferred treatment in areas where tetracycline-resistant V cholerae are common. In V cholerae, in-vitro doxycycline susceptibilities are not a useful indicator of the in-vivo efficacy of the drug.

Ciprofloxacin. An updated review of its pharmacology, therapeutic efficacy and tolerability

Ciprofloxacin is a broad spectrum fluoroquinolone antibacterial agent. Since its introduction in the 1980s, most Gram-negative bacteria have remained highly susceptible to this agent in vitro; Gram-positive bacteria are generally susceptible or moderately susceptible. Ciprofloxacin attains therapeutic concentrations in most tissues and body fluids. The results of clinical trials with ciprofloxacin have confirmed its clinical efficacy and low potential for adverse effects. Ciprofloxacin is effective in the treatment of a wide variety of infections, particularly those caused by Gram-negative pathogens. These include complicated urinary tract infections, sexually transmitted diseases (gonorrhoea and chancroid), skin and bone infections, gastrointestinal infections caused by multiresistant organisms, lower respiratory tract infections (including those in patients with cystic fibrosis), febrile neutropenia (combined with an agent which possesses good activity against Gram-positive bacteria), intra-abdominal infections (combined with an antianaerobic agent) and malignant external otitis. Ciprofloxacin should not be considered a first-line empirical therapy for respiratory tract infections if penicillin-susceptible Streptococcus pneumoniae is the primary pathogen; however, it is an appropriate treatment option in patients with mixed infections (where S. pneumoniae may or may not be present) or in patients with predisposing factors for Gram-negative infections. Clinically important drug interactions involving ciprofloxacin are well documented and avoidable with conscientious prescribing. Recommended dosage adjustments in patients with impaired renal function vary between countries; major adjustments are not required until the estimated creatinine clearance is < 30 ml/min/1.73m2 (or when the serum creatinine level is > or = 2 mg/dl). Ciprofloxacin is one of the few broad spectrum antibacterials available in both intravenous and oral formulations. In this respect, it offers the potential for cost savings with sequential intravenous and oral therapy in appropriately selected patients and may allow early discharge from hospital in some instances. In conclusion, ciprofloxacin has retained its excellent activity against most Gram-negative bacteria, and fulfilled its potential as an important antibacterial drug in the treatment of a wide range of infections. Rational prescribing will help to ensure the continued clinical usefulness of this valuable antimicrobial drug.