Infectious Disease Consult

Commonly used antibiotics in ObGyn practice

OBG Manag. 2022 May;34(5):29, 36-40 | doi: 10.12788/obgm.0191

References

Duff P. Maternal and perinatal infection in pregnancy: bacterial. In: Landon MB, Galan HL, Jauniaux ERM, et al, eds. Gabbe’s Obstetrics: Normal and Problem Pregnancies, 8th ed. Elsevier; 2020: chapter 58.
Duff P. Antibiotic selection in obstetrics: making cost-effective choices. Clin Obstet Gynecol. 2002;45:59-72.
Wagenlehner FME, Cloutier DJ, Komirenko AS, et al; EPIC Study Group. Once-daily plazomicin for complicated urinary tract infections. N Engl J Med. 2019;380:729-740.
Leffler DA, Lamont JT. Clostridium difficile infection. N Engl J Med. 2015;372:1539-1548.
Duff P. Prevention of infection after cesarean delivery. Clin Obstet Gynecol. 2019;62:758-770.
Hooper DC, Wolfson JS. Fluoroquinolone antimicrobial agents. N Engl J Med. 1991;324:384-394.
Castells M, Khan DA, Phillips EJ. Penicillin allergy. N Engl J Med. 2019 381:2338-2351.
St Cyr S, Barbee L, Workowski KA, et al. Update to CDC’s treatment guidelines for gonococcal infection, 2020. MMWR Morbid Mortal Wkly Rep. 2020;69:1911-1916.
Ray WA, Murray KT, Hall K, et al. Azithromycin and the risk of cardiovascular death. N Engl J Med. 2012;366:1881-1890.
Workowski KA, Bolan GA. Sexually transmitted disease treatment guidelines, 2015. MMWR Morbid Mortal Wkly Rep. 2015;64(RR3):1-137.
Duff P. UTIs in pregnancy: managing urethritis, asymptomatic bacteriuria, cystitis, and pyelonephritis. OBG Manag. 2022;34(1):42-46.
Crider KS, Cleves MA, Reefhuis J, et al. Antibacterial medication use during pregnancy and risk of birth defects prevalence study. Arch Pediatr Adolesc Med. 2009;163:978985.
Alvarez-Arango S, Ogunwole SM, Sequist TD, et al. Vancomycin infusion reaction—moving beyond “red man syndrome.” N Engl J Med. 2021;384:1283-1286.
Finley TA, Duff P. Antibiotics for treatment of staphylococcal infections in the obstetric patient. Clin Obstet Gynecol. 2019;62:790-803.

Fluorinated quinolones

The fluorinated quinolones include several agents, but the 3 most commonly used in our specialty are ciprofloxacin, ofloxacin, and levofloxacin. All 3 drugs can be administered orally; ciprofloxacin and levofloxacin also are available in intravenous formulations. These drugs interfere with bacterial protein synthesis by targeting DNA gyrase, an enzyme that introduces negative supertwists into DNA and separates interlocked DNA molecules.

These drugs provide excellent coverage against gram-negative bacilli, including Haemophilus influenzae; gram-negative cocci, such as N gonorrhoeae, Neisseria meningitidis, and Moraxella catarrhalis; and many staphylococci species. Levofloxacin, but not the other 2 drugs, provides moderate coverage against anaerobes. Ofloxacin and levofloxacin are active against chlamydia. Levofloxacin also covers the mycoplasma organisms that are responsible for atypical pneumonia.

As a group, the fluorinated quinolones are moderately expensive. The most likely adverse effects with these agents are gastrointestinal (GI) upset, headache, agitation, and sleep disturbance. Allergic reactions are rare. These drugs are of primary value in our specialty in treating gonorrhea, chlamydia, complicated UTIs, and respiratory tract infections.^1,2,6

The penicillins

Penicillin

Penicillin, a β-lactam antibiotic, was one of the first antibiotics developed and employed in clinical practice. It may be administered orally, intramuscularly, and intravenously. Penicillin exerts its effect by interfering with bacterial cell wall synthesis. Its principal spectrum of activity is against aerobic streptococci, such as group A and B streptococcus; most anaerobic gram-positive cocci that are present in the vaginal flora; some anaerobic gram-negative bacilli; and T pallidum. Penicillin is not effective against the majority of staphylococci species, enterococci, or aerobic gram-negative bacilli, such as Escherichia coli.

Penicillin’s major adverse effect is an allergic reaction, experienced by less than 10% of recipients.⁷ Most reactions are mild and are characterized by a morbilliform skin rash. However, some reactions are severe and take the form of an urticarial skin eruption, laryngospasm, bronchospasm, and overt anaphylaxis. The cost of both oral and parenteral penicillin formulations is very low. In obstetrics and gynecology, penicillin is used primarily for the treatment of group A and B streptococci infections, clostridial infections, and syphilis.^1,2

Ampicillin and amoxicillin

The β-lactam antibiotics ampicillin and amoxicillin also act by interfering with bacterial cell wall synthesis. Amoxicillin is administered orally; ampicillin may be administered orally, intramuscularly, and intravenously. Their spectrum of activity includes group A and B streptococci, enterococci, most anaerobic gram-positive cocci, some anaerobic gram-negative bacilli, many aerobic gram-negative bacilli, and clostridial organisms.

Like penicillin, ampicillin and amoxicillin may cause allergic reactions that range from mild rashes to anaphylaxis. Unlike the more narrow-spectrum penicillin, they may cause antibiotic-associated diarrhea, including C difficile colitis,⁴ and they may eliminate part of the normal vaginal flora and stimulate an overgrowth of yeast organisms in the vagina. The cost of ampicillin and amoxicillin is very low. These 2 agents are used primarily for treatment of group A and B streptococci infections and some UTIs, particularly those caused by enterococci.^1,2

Dicloxacillin sodium

This penicillin derivative disrupts bacterial cell wall synthesis and targets primarily aerobic gram-positive cocci, particularly staphylococci species. The antibiotic is not active against MRSA. The principal adverse effects of dicloxacillin sodium are an allergic reaction and GI upset. The drug is very inexpensive.

The key application for dicloxacillin sodium in our specialty is for treatment of puerperal mastitis.¹

Continue to: Extended-spectrum penicillins...