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PH8.4 | PH8.4 | Syndromic Antibacterial Treatment Plans — SDL Guide — SDL Guide

Learning Objectives

• Devise a pharmacotherapeutic plan for UTI (uncomplicated, complicated, pyelonephritis) with appropriate drug, dose, and duration
• Devise a pharmacotherapeutic plan for common STDs (gonorrhoea, chlamydia, syphilis, PID)
• Explain patient instructions for adherence and partner notification
• Apply Indian resistance data to empiric antibiotic selection for UTI and STD

INSTRUCTIONS

Pharmacotherapeutic planning translates drug-class knowledge into patient-specific prescriptions. For UTI and STDs — the two syndromic groups in PH8.4 — the plan must include the right drug, the right dose, the right duration, AND the instructions you give the patient. In India, rising fluoroquinolone resistance in both UTI pathogens and Neisseria gonorrhoeae has changed first-line choices in the last decade. This SDL builds practical prescribing skills.

References

• Tripathi KD. Essentials of Medical Pharmacology, 8th ed., Ch 58, 63 (textbook)
• WHO Guidelines for the Treatment of Gonorrhoea, Chlamydial Infections, Syphilis, 2016 updated 2022 (guideline)
• IDSA Guidelines: UTI in Women 2022 (guideline)

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Version 2.0 | NMC CBUC 2024

Pathophysiology of UTI and STD: Why Syndrome-Based Planning Matters

Urinary tract infections (UTIs) result from ascending colonisation of the urinary tract, predominantly by enteric gram-negative bacteria. Escherichia coli accounts for 70–85% of community-acquired UTIs in India; other pathogens include Klebsiella pneumoniae (10–15%), Staphylococcus saprophyticus (young women, 5–10%), Enterococcus faecalis, and Proteus mirabilis. The ascending route (urethra → bladder → ureter → kidney) explains why UTI is more frequent in women (shorter urethra, proximity to rectal flora), sexually active patients, those with structural abnormalities (vesicoureteral reflux, stones, obstruction), catheterised patients, and those with diabetes (glycosuria promotes bacterial growth).

Pathogens causing UTI express virulence factors that facilitate adherence and ascent: P fimbriae (type 1 and P pili in uropathogenic E. coli) mediate urothelial adhesion; hemolysin damages urothelial cells; siderophores (aerobactin) acquire iron for growth. Understanding these pathogenesis factors contextualises why some patients have recurrent UTIs (residual fimbriated E. coli in urothelial cells) and why simple hydration and voiding behaviour are non-pharmacological first-line strategies.

Sexually transmitted infections follow a different epidemiology: transmission is by direct contact of mucous membranes or skin. Neisseria gonorrhoeae infects columnar epithelium — urogenital, rectal, pharyngeal. It is an obligate human pathogen with efficient immune-evasion mechanisms (IgA protease, antigenic variation of pili and outer-membrane proteins). Critically, N. gonorrhoeae has developed resistance sequentially to sulfonamides → penicillin → tetracyclines → fluoroquinolones → now extended-spectrum cephalosporins (rare but reported). This resistance history is why each successive WHO gonorrhoea treatment guideline has escalated to a more powerful last-resort drug.

Chlamydia trachomatis (serovars D–K for urogenital) is an obligate intracellular organism that resides within host-cell vacuoles (inclusions), making it invisible to β-lactam antibiotics (which cannot penetrate cells). Only intracellularly-active drugs — doxycycline, azithromycin, fluoroquinolones — are effective. This explains why treating chlamydial cervicitis with amoxicillin fails completely. Treatment of chlamydia is further complicated by frequent asymptomatic carriage (up to 70% of women, 50% of men infected) — underscoring the importance of partner treatment.

Goal of Syndromic Treatment: Cure, Prevent Complications, Stop Transmission

The pharmacotherapeutic plan for UTI and STDs has three simultaneous objectives, all of which must be addressed in the prescription and patient counselling:

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1. Microbiological cure — eradication of the causative organism from the infection site. For UTI, this is confirmed by test-of-cure urine culture 5–7 days after treatment (mandatory only in complicated UTI, pregnancy, and paediatric UTI; not required for uncomplicated UTI in non-pregnant adult women where symptom resolution is the endpoint). For STD, test-of-cure culture or NAAT (nucleic acid amplification test) 2–4 weeks after treatment detects treatment failure.

2. Prevention of ascending complications — the second objective is preventing untreated lower UTI from ascending to pyelonephritis, or untreated urogenital STD from ascending to cause: pelvic inflammatory disease (PID — most serious complication of gonorrhoea/chlamydia in women, causing tubo-ovarian abscess and tubal infertility); epididymo-orchitis in men; haematogenous dissemination (disseminated gonococcal infection — skin pustules, septic arthritis, rare meningitis/endocarditis).

3. Interruption of transmission — treating the patient alone is insufficient for STDs. Partner notification and treatment are integral to the prescription. In India, syndromic management guidelines from the National AIDS Control Programme (NACP) recommend treating sex partners presumptively (without waiting for test results) because: (a) most partners will be culture-positive; (b) waiting for test results leads to reinfection before treatment. 'Expedited partner therapy' (EPT) — prescribing medication for the partner — is evidence-based.

The prescriber must explain all three objectives to the patient. Patients who understand WHY they need to complete the course, WHY their partner needs treatment, and WHEN to return (if symptoms persist or worsen) have significantly better outcomes than those who receive a prescription without explanation.

UTI Classification and Treatment Framework

UTI classification drives treatment choice because the site of infection and host factors determine which drugs will work, which are unnecessary, and what duration is needed.

Uncomplicated lower UTI (acute bacterial cystitis) — young, non-pregnant women with dysuria, frequency, urgency; no fever, no flank pain, no structural urinary abnormality. The diagnosis is clinical + urine dipstick/microscopy; culture is optional (recommended if symptoms persist or recur within 4 weeks).

First-line treatment options (Indian context — 2024):
- Nitrofurantoin 100mg modified-release twice daily × 5 days: preferred — achieves high urinary concentrations, minimal systemic absorption, low resistance rates. Contraindicated: eGFR <30 mL/min (insufficient urinary concentration AND systemic accumulation risk), pyelonephritis (inadequate tissue levels), glucose-6-phosphate dehydrogenase deficiency (haemolysis). Take with food to improve absorption and reduce GI irritation.
- Fosfomycin trometamol 3g single dose (sachet): high urinary levels via concentration in proximal tubule; single dose is an advantage for adherence. Active against most ESBL-producing E. coli — useful when ESBL suspected in uncomplicated UTI.
- TMP-SMX 960mg (1 DS tablet) BD × 3 days: only appropriate if local E. coli resistance is < 20% (check hospital antibiogram — many Indian hospitals now exceed 30–40% resistance).
- Fluoroquinolones (ciprofloxacin, norfloxacin): effective but NOT first-line for uncomplicated UTI due to broad-spectrum nature (drives resistance, C. difficile risk) and rising local resistance in India. Reserve for complicated UTI and pyelonephritis.

Acute uncomplicated pyelonephritis — fever >38°C, flank pain/costovertebral angle tenderness, pyuria. Urine culture MANDATORY (blood cultures if systemically unwell). Oral outpatient therapy appropriate for mild-moderate cases: ciprofloxacin 500mg BD × 7 days OR levofloxacin 750mg once daily × 5 days OR cefixime 400mg BD × 10–14 days (beta-lactam, less efficacious — 14 days). IV therapy (ceftriaxone 1–2g once daily or meropenem for ESBL) for severely ill, vomiting, pregnant women, or failure of oral therapy.

Complicated UTI — any UTI in a patient with structural/functional urinary abnormality (obstruction, stones, vesicoureteral reflux, neurogenic bladder), men (UTI in men is always complex — rule out prostatitis, STD, structural cause), diabetics, immunosuppressed, recent instrumentation. Broader-spectrum therapy (quinolone or cephalosporin) based on culture. Duration 7–14 days. Remove/manage the complicating factor.

Catheter-associated UTI (CAUTI) — treat only if symptomatic (fever, rigors, flank pain, change in mental status in elderly); do NOT treat asymptomatic bacteriuria in catheterised patients — it does not benefit the patient and drives resistance. If treatment is needed: culture-directed; remove catheter and change if possible. Duration: 5–7 days (7–14 days if slow to respond).

Recurrent UTI (≥3 episodes/year in women): investigate for anatomical cause. Prophylactic strategies: low-dose nitrofurantoin 50mg daily × 6–12 months; post-coital single-dose nitrofurantoin; cranberry (modest evidence for PABA/mannose mechanism). Avoid long-term fluoroquinolone prophylaxis (drives resistance).