Podcast Summary: Dr. Chapa’s OBGYN Clinical Pearls

Episode: When ZMAX if OUT for CS: Alternative?
Date: January 31, 2026
Host(s): Dr. Chapa, Podcast Co-host

Overview

This episode addresses a pressing clinical dilemma facing many obstetric providers: What are the best, evidence-based alternatives for extended-spectrum antibiotic prophylaxis at cesarean section (CS) when intravenous azithromycin (Zithromax/ZMAX) is unavailable? Dr. Chapa and his co-host break down landmark trials, current guidelines, alternatives in the setting of shortages, and the microbiological rationale for various regimens—all delivered in their signature, engaging, and practical style.

Key Discussion Points & Insights

1. Importance of Azithromycin for Cesarean Prophylaxis

• Landmark Evidence: The CSOAP trial (2016, NEJM) established the benefit of adding IV azithromycin 500mg to routine first-generation cephalosporin for women undergoing intrapartum cesarean (especially with ruptured membranes).
  • Quote:
    "There was a 51% reduction in the composite outcome of endometritis, wound infection, and or other infectious morbidity." — Dr. Chapa, [12:57]
• Expanded Indications:
  • Now also routinely considered for women with obesity (per ERAS/IRAC trials).
  • Patient groups: Intrapartum CS, ruptured membranes (with/without labor), and patients "living with obesity."

2. What If Azithromycin Is Unavailable?

• The Problem: Supply issues—common during COVID and sometimes local shortages—leave clinicians without Zithromax. No formal guideline provides a clear substitute.
  • Quote:
    "What is a good evidence-based alternative here?...there's really nothing that says if this is not available, use this one—we've got to go again digging through the data." — Dr. Chapa, [05:09]

3. Microbiological Rationale

• Why Azithromycin?
  • Targets atypical pathogens (ureaplasma and mycoplasma) associated with post-op infection that aren’t well-covered by cephalosporins alone.
  • Gentamicin + Clindamycin: First-line for severe beta-lactam allergy, but NOT effective against ureaplasma/mycoplasma.
    • "Neither gent nor clinda hit ureaplasma or mycoplasma, which some women have and increases the risk of metritis and overall wound infection." — Dr. Chapa, [06:44]

4. Preoperative Alternative: Oral Clarithromycin

• Evidence:
  • Small prospective observational study (2020, 240 patients; COVID-era) substituted oral clarithromycin (single dose, 30 min pre-op) for azithromycin:
    • Resulted in a 55% reduction in endometritis vs. cephalosporin alone.
  • Quote:
    "Clarithromycin also resulted in a 55% reduction in endometritis compared to standard cephalosporin use alone." — Dr. Chapa, [14:11]
  • Caveat: Only one study; no large RCTs to date. Still, effect size was similar to azithromycin.

5. Postoperative Alternative: 2 Days Cefalexin + Metronidazole

• Amy Valent’s JAMA Study:
  • 2 days of oral Keflex (cephalexin) + Flagyl (metronidazole) post-op as an infection-prevention strategy.
  • Pros: Evidence of reduced wound infection.
  • Cons:
    • Not clearly effective against atypical organisms (mycoplasma/ureaplasma).
    • Multi-dose, compliance may be challenging postpartum.
  • Quote:
    "But it's two days and it's multi dose administration. And it's unclear if that's really targeting mycoplasma." — Dr. Chapa, [15:55]

6. Gentamicin + Clindamycin in Cephalosporin/Penicillin Allergy

• Use: Remains first-line for those with severe allergy but insufficient alone for atypical coverage.
• Indirect coverage: Some theoretical reduction by suppressing “travel buddy” anaerobes, but not direct.
  • Quote:
    "Gent and clinda...is not sufficient enough to cover for these atypicals that Zithromax is aimed for." — Dr. Chapa, [07:54]

7. Microbiological Nuance

• Ureaplasma: Can be normal flora or sexually transmitted—gray area, not always a pathogen.
• Mycoplasma genitalium: Always a pathogen (STI per CDC guidance).
• Metronidazole: May have indirect or minimal benefit for mycoplasma in some settings, but not proven standard.

Recommended Clinical Approaches

(Timestamp [17:30])

• Preferred (if Zithromax unavailable):
  1. Pre-op oral clarithromycin (single dose, 30-60 min before incision) — based on small but promising data. Stays within drug class, easy administration.
     • "You can either tackle that pre op, as we talked about, with an oral clarithromycin dose, single dose..." — Podcast Co-host, [17:30]
  2. Post-op two days of cephalexin + metronidazole — if pre-op alternative is not feasible and local policy or patient factors allow.
  3. Gentamicin + clindamycin — for patients with beta-lactam allergy, with understanding of its limitations for atypicals.

Notable Quotes & Memorable Moments

• On Alternative Drug Logic:
  • "Stick to the same class…Clar-ithromycin is a very close relative of azithromycin and taken orally with small sips of water is not gonna affect anything and still be NPO. It's okay within 30 minutes, definitely within the hour." — Dr. Chapa, [15:27]
• On Evidence Gaps and Pragmatism:
  • "It would be nice if there was...guidance that said if Zithromax is not available on the shelf, do this one. But there isn't." — Dr. Chapa, [13:32]
• On Treating Ureaplasma vs. Mycoplasma:
  • "Ureaplasma isn’t always kind of a bad guy, okay? Ureaplasma can be a background part of the microflora...Mycoplasm, on the other hand, mycoplasm is always bad, okay?" — Dr. Chapa, [16:37]

Episode Timeline

| Timestamp | Segment / Topic | |-----------|-----------------------------------------| | 01:05 | Introduction, clinical conundrum set-up | | 05:09 | Rationale for Zithromax in CS | | 06:44 | Gent+Clinda insufficient for atypicals | | 12:57 | CSOAP trial & 51% infection reduction | | 14:11 | Oral clarithromycin study | | 15:27 | Practical notes on oral clarithromycin | | 15:55 | Discussion of post-op Keflex+Flagyl | | 16:37 | Ureaplasma vs. Mycoplasma nuances | | 17:30 | Summing up alternative regimens |

Tone and Style

Dr. Chapa’s delivery is energetic, practical, and peppered with humor. The episode mixes deep evidence-based reasoning with memorable, relatable analogies for clinical practice.

Final Takeaway

If IV Azithromycin is unavailable for extended-spectrum CS prophylaxis:

• Oral clarithromycin (single pre-op dose) is the best evidence-supported substitute based on current (though limited) data.
• Post-op 2-day cephalexin/metronidazole is an option, but has downsides.
• For penicillin/cephalosporin allergy, gentamicin+clindamycin remains standard, though does not reliably cover atypical bacteria.

Always consider local infectious risks, available resources, and patient characteristics when adapting antibiotic protocols.

For further reading, check the cited studies in the episode notes and stay tuned for updates to guidelines in this rapidly evolving area.