European Journal of Cardiovascular Medicine

Shigella species which belongs to the family Enterobacteriaceae is one of the main causes of sickness and mortality among children in developing nations.(1)

In 1897, Shigella was identified as the cause of dysentery when Japanese microbiologist Kiyoshi Shiga isolated the Shiga bacillus (now known as Shigella dysenteriae type 1) from patient faeces during a massive and disastrous dysentery outbreak.(2) It is a clinical syndrome marked by fever, cramping in the intestines, and frequent passage of small, bloody, mucopurulent stools.

Globally, both endemic and epidemic types of shigellosis are found.(3) Recent estimates suggest that Shigella is responsible for nearly 125 million diarrhoeal cases each year, resulting in approximately 160,000 deaths, with about one-third occurring in young children.(4,5)

The short- and long-term decline in the nutritional status of children infected with shigellosis in endemic areas is a consequence of the disease. The patient's nutritional status causes exudative enteropathy and anorexia, which quickly worsens due to mucosal abrasions. As a result, shigellosis contributes significantly to stunted growth in children in developing countries.(6)

Growing resistance to several antibiotics has been a significant factor in the treatment of shigellosis since the middle of the 1960s. The clonal expansion of particular strains and the horizontal transmission of resistance genes via plasmids and transposons are two examples of the processes that drive resistance patterns, which differ by location.(7) Globally, quinolones like nalidixic acid are becoming more popular because of increased resistance rates to conventional first-line medications like amoxicillin. However, many regions adopted later-generation quinolones as first-line therapy because resistance to these early-generation quinolones quickly developed, primarily as a result of chromosomal abnormalities in DNA gyrase and topoisomerase IV. For instance, when second-generation quinolones, such as ofloxacin, ciprofloxacin, and norfloxacin, were first released in India in the late 1980s, they proved to be quite successful, even against Shigella dysenteriae type 1 that was resistant to many drugs.(1)

Antibiotics are not recommended for simple, self-limiting gastroenteritis. However, in extreme situations, antibiotic therapy is advised in addition to fluid and haemodynamic care, especially when dehydration, hypotension, or immunocompromised patients are involved. Antibiotic susceptibility testing need to direct treatment wherever feasible. Common options include a fluoroquinolone, including ciprofloxacin (500mg oral twice daily) for 3-5 days, or levofloxacin (500 mg oral once daily) for 3–5 days or, ceftriaxone (1–2 g intravenously once daily) for 5 days, Azithromycin (500 mg orally once daily for three days) or trimethoprim–sulfamethoxazole (160/80 mg orally twice daily for five days) are also effective if the pathogen is sensitive. Amoxicillin and ampicillin are rarely effective because of their high rates of resistance.(8) Table 1 shows recommended antimicrobial therapy for shigellosis as mentioned in Harrison’s textbook 22nd edition.(9)

Often, antibiotic selection is not made with sufficient care, relying instead on past experience or the influence of pharmaceutical marketing.(10,11) To address this issue and ensure that hospital-based drugs are reserved for patients who truly need them—and for conditions where they are most effective—there is a need for P-drug (personal drug) development. The goal of this approach is to encourage safe, effective, and cost-conscious prescribing.

Part 2 of the WHO Guide to Good Prescribing, which stresses the prudent use of necessary medications, describes the personal drug idea in practical terms as a personal formulary.(12) A companion resource, the Teachers’ handbook to Good Prescribing, was released in 2001 to assist medical educators in integrating the WHO handbook into their instruction. This approach strengthens students' clinical reasoning abilities by teaching them how to make therapeutic decisions and giving them systematic, step-by-step exposure to the process, which is the cornerstone of rational prescribing.

Therefore, this study was conducted to made personal formulary for treatment of bacillary dysentery.

This cross-sectional study was carried out in the Department of Pharmacology, at a tertiary care centre among the residents. Personal formulary for antibiotic therapy of bacillary dysentery was developed by using various standard text books, journals available in the library and on internet. Current Index of Medical Specialties (CIMS) was used to determine cost of drugs.(13) Residents were taught about how to analyze and give score (α) to drugs used for bacillary dysentery available in market. Four parameters according to bacillary dysentery concept of Joshi and Jayawick Ramarajah(14), efficacy (0.4), safety (0.3), cost (0.2) and convenience (0.1) was taken into consideration for each group and their drugs. 1. Efficacy was derived according to the efficacy profile written in standard text books. Drug with more efficacy were given higher score. 2. Safety of a drug were described according to the side effect profile written in standard text books. Drug with more side effects were given lower score. 3. Cost was compared by taking average of costs of different brands written in Current Index of Medical Specialties (CIMS). 4. Convenience was compared according to the availability of drug, dosage form, dosage schedule, route of administration.(15) Score was given to each four parameters from 1 to 10 for each drug. Each parameter was given a fractional numerical rating (β) according to the importance i.e. 0.4 for efficacy, 0.3 for safety, 0.2 for cost and 0.1 for convenience. Score (α) was multiplied by fractional numerical rating (β) to get total score (γ=α x β). Higher total score indicates a better value. The drug with the highest score became the personal drug choice. Then the senior residents and postgraduate kept a copy of personal drug description as a personal formulary.(14–16)

Scores was given to different drug groups for treatment of bacillary dysentery in adults and children as described in table 2. Fluoroquinolone, Macrolide and Cephalosporin were taken as different drug groups and among these, fluoroquinolone had the highest total score of 8.2. Among fluoroquinolones, ciprofloxacin had the highest score (Table 3).

Table 4 shows about the description of ciprofloxacin as a personal formulary for bacillary dysentery.

Tables:

Table 1: Recommended antimicrobial therapy for shigellosis

Table 2: Selection of Personal Formulary from Drug Groups for Bacillary Dysentery

Comparison of major antimicrobial drug groups using a structured p-drug selection matrix. Each drug class is scored on efficacy, safety, cost, and convenience, multiplied by predetermined weights (0.4, 0.3, 0.2, and 0.1, respectively). Weighted totals indicate the overall suitability of each group.

Table 3: Selection of Personal Formulary

Evaluation of antimicrobial options for bacillary dysentery using a structured WHO p-drug scoring system. Raw scores (1–10) were assigned for efficacy, safety, cost, and convenience, multiplied by predetermined weights, and summed to generate a composite total. Among evaluated drugs, ciprofloxacin scored highest (8.6), followed by ofloxacin (8.3), levofloxacin (8.2), azithromycin (7.9), and ceftriaxone (7.7).

Table 4: Description of Ciprofloxacin as Personal Formulary Bacillary Dysentery

Recommended ciprofloxacin dosage for bacillary dysentery and key patient-counselling points, including essential information, common side effects, contraindications, instructions, and follow-up advice.

The development of a personal formulary using the P-drug concept allows a systematic, rational, and context-specific approach to antibiotic selection in bacillary dysentery.(17) The requirements are addressed by the WHO Good Prescribing Guide, which offers medical students a structured model of medical consultation and a six-step framework for rational prescribing. These steps include: (1) describing the patient’s problem, (2) selecting an appropriate medicine, (3a) assessing the suitability of a standard p-drug for the disease in general, (3b) verifying its suitability for the specific patient and modifying it if needed, (4) writing the prescription and initiating treatment, (5) providing necessary information to the patient, and (6) monitoring treatment. A key principle of this approach is the clear distinction between Step 3a and Step 3b, ensuring that drug choice is not only evidence-based but also tailored to the individual patient.

Postgraduate students, who serve as educators for undergraduates, are trained to promote standardized treatment for common disorders while simultaneously developing personalized prescribing strategies. This is achieved through the use of national and international treatment guidelines, formularies, textbooks, and other reliable drug information resources. The ultimate goal is to prepare future physicians to apply both standardized drug selection methods and individualized modifications to ensure safe, rational, and patient-centered therapy.(16)

In this study, four antibiotic classes—fluoroquinolones, macrolides, cephalosporins, and penicillins—were evaluated based on efficacy, safety, cost, and convenience. Among fluoroquinolones, ciprofloxacin scored the highest overall. Ciprofloxacin, administered 500 mg twice daily for 3–5 days in adults and 15mg/kg twice daily for 3 days in children, emerged as the first-line P-drug owing to its high efficacy and safety, wide availability, and low cost, in agreement with WHO and national guideline recommendations. According to WHO(18), Ciprofloxacin is currently the recommended medication for all patients with bloody diarrhoea, regardless of age. Quinolones have been shown to induce arthropathy in immature animals, however the risk of joint injury in children seems to be low and is far exceeded by the benefits of using these medications to treat this potentially fatal condition.

Levofloxacin 500mg once daily for 3-5 days demonstrated similar efficacy and lesser safety compared to ciprofloxacin but was slightly more expensive; however, its once-daily dosing regimen offers improved compliance, making it a suitable alternative when adherence is a concern. Ofloxacin 200mg twice daily for 3-5 days, another second-generation fluoroquinolone, and remains an effective oral option where local susceptibility data support its use; however, like ciprofloxacin it requires twice-daily dosing. Ofloxacin is given twice daily while levofloxacin is given once daily, so levofloxacin has better compliance. Ciprofloxacin has slightly better in vitro activity against Shigella species compared to ofloxacin, especially resistant strains. According to WHO, Ciprofloxacin is found to be safer in children so has maximum score in safety as compared to levofloxacin and ofloxacin.

Azithromycin 500mg once daily for 3 days, a macrolide, scored favorably as a second-line choice, particularly in areas with fluoroquinolone resistance, or in special populations such as children and pregnant women where fluoroquinolones (except ciprofloxacin) are contraindicated. Its short course and once-daily dosing are convenient, but concerns about rising resistance and higher cost compared with ciprofloxacin reduce its priority as a first-line option.

Ceftriaxone 1-2 gm intravenous once daily, a third-generation cephalosporin, was identified as a valuable agent in severe or complicated dysentery, particularly in hospitalized patients. Its excellent efficacy is offset by the need for parenteral administration, which reduces convenience and increases indirect treatment costs. Cefixime, the oral cephalosporin, was not prioritized because of limited evidence of robust efficacy against Shigella compared to ceftriaxone.

Although pivmecillinam has been recognized in WHO guidelines as an effective drug against shigellosis, it was not included in the scoring table because it is not available in India. (18) Likewise, trimethoprim–sulfamethoxazole, historically a first-line agent, has lost clinical utility due to high resistance rates in Shigella isolates across South Asia and is now considered only in resistant cases where sensitivity is confirmed;(19) for this reason, it was also excluded from the present P-drug scoring.

The findings therefore reaffirm ciprofloxacin as the preferred first-line personal drug for bacillary dysentery in the Indian context, with levofloxacin as a compliance-friendly alternative, azithromycin as an effective second-line option, and ceftriaxone reserved for severe, resistant, or hospitalized cases. This stepwise selection based on efficacy, safety, cost, and convenience illustrates the value of the P-drug concept in promoting rational prescribing and minimizing inappropriate antibiotic use.

The P-drug approach provides a structured framework for rational antibiotic selection in bacillary dysentery. Ciprofloxacin remains the most appropriate first-line personal drug due to its favorable balance of efficacy, safer in both adults and children, cost, and availability. Levofloxacin may be considered as an alternative in adults where once-daily dosing enhances compliance. Ofloxacin has lesser score as compared to Ciprofloxacin. Azithromycin serves as a reliable option in resistant cases and special populations, while ceftriaxone should be reserved for severe disease requiring parenteral therapy. Pivmecillinam, though effective, is not available in India, and trimethoprim–sulfamethoxazole is no longer considered first-line due to widespread resistance. Adopting such a structured formulary can help ensure safe, effective, and cost-conscious antibiotic prescribing for bacillary dysentery.

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4.             GBD Diarrhoeal Diseases Collaborators. Estimates of global, regional, and national morbidity, mortality, and aetiologies of diarrhoeal diseases: a systematic analysis for the Global Burden of Disease Study 2015. Lancet Infect Dis. 2017 Sep;17(9):909–48.

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6.             Bagamian KH, Anderson IV JD, Blohm G, Scheele S. Shigella and childhood stunting: Evidence, gaps, and future research directions. PLoS Negl Trop Dis. 2023 Sep 12;17(9):e0011475.

7.             Baker KS, Dallman TJ, Field N, Childs T, Mitchell H, Day M, et al. Horizontal antimicrobial resistance transfer drives epidemics of multiple Shigella species. Nat Commun. 2018 Apr 13;9:1462.

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19.          Salleh MZ, Nik Zuraina NMN, Hajissa K, Ilias MI, Banga Singh KK, Deris ZZ. Prevalence of Multidrug-Resistant and Extended-Spectrum Beta-Lactamase-Producing Shigella Species in Asia: A Systematic Review and Meta-Analysis. Antibiotics. 2022 Nov 18;11(11):1653.