Antibiotic Treatment of Common Infections

Educational Objectives

The goal of this program is to improve diagnosis and treatment of bacterial infections. After hearing and assimilating this program, the clinician will be better able to:

1. List some risks and benefits of fosfomycin for treatment of urinary tract infection.
2. Prescribe safe and effective treatment for an upper respiratory viral infection.
3. Manage recurrent Clostridium difficile.

Summary

Diagnosis of urinary tract infection (UTI): cultures likely not needed for first episode of uncomplicated, bacterial cystitis; most infections caused by Escherichia coli; in study of >200 women with apparent uncomplicated cystitis, patients provided midstream clean catch, then catheterized specimen; E coli cause of most UTIs, but many patients had gram-positive contaminants in clean catch

Fluoroquinolones for UTI: previously overused; adverse effects — include rupture of Achilles and other tendons, flare of myasthenia gravis, peripheral neuropathy, effects on central nervous system, anxiety, depression, hallucinations, suicidal thoughts, confusion, sunburn, severe diarrhea, and Clostridium difficile; US Food and Drug Administration — fluoroquinolones should be reserved for patients in whom no other treatment options available for treatment of acute bacterial sinusitis, exacerbation of chronic bronchitis, and uncomplicated UTI; risks generally outweigh benefits in such patients; however, for some serious infections, benefits of fluoroquinolones outweigh risks

Delaying treatment for UTI: Gupta and Stamm — showed that number needed to treat (NNT) to benefit women with UTI ≈5; UTI may clear spontaneously; Little et al — evaluated patients with presumptive diagnosis of uncomplicated UTI and equivocal findings or contamination on urinalysis; patients randomized to antibiotics vs observation for 2 days until culture available; study showed that fewer antibiotics may be used; women in delayed-treatment group did not develop pyelonephritis; need for antibiotics in question (unknown whether bacteria themselves or inflammatory response in bladder responsible for illness); randomized trial — treated women with fosfomycin or ibuprofen; patients in fosfomycin group rarely needed another antibiotic; one-third of those in ibuprofen group ultimately treated with antibiotic, suggesting that NNT 3; more symptoms and more pyelonephritis reported in ibuprofen group; delaying treatment reasonable if diagnosis uncertain or patient does not want antibiotics, and reliable follow-up planned

Guidelines for treatment of UTI: Infectious Diseases Society of America (IDSA) recommends nitrofurantoin, trimethoprim-sulfamethoxazole (TMP-SMX; unless local rate of resistance >20%), or fosfomycin; fluoroquinolones and cefpodoxime second-line agents; however, guideline likely to be revised to reflect warning from FDA regarding fluoroquinolones

Fosfomycin: safer than fluoroquinolones, with equivalent efficacy; effective for acute, uncomplicated cystitis but not pyelonephritis; single dose adequate; however, drug expensive, not carried in some pharmacies, and may trigger migraine or diarrhea

Cefpodoxime for UTI: oral analog of ceftriaxone; less effective than ciprofloxacin; study randomized women to 3 days of ciprofloxacin or cefpodoxime; patients in ciprofloxacin arm more likely to clear urine and less likely to have persistent vaginal colonization with E coli; study found that cefpodoxime not noninferior to ciprofloxacin; 3 days of low-dose cefpodoxime not appropriate (higher dose should be used for 7 days)

Upper respiratory infection (URI): common culprits rhinovirus, coronavirus, and adenovirus; bacterial infections usually associated with respiratory tract organisms such as pneumococci and Haemophilus spp; 1 in 50 URIs bacterial; symptomatic treatment important to help area drain and relieve symptoms; symptoms often do not help clinician distinguish between viral and bacterial infections; color of mucus unrelated to type of microbe; symptoms lasting >10 days and fever suggest bacterial etiology

Treatment of URI: among patients with URI of any etiology, NNT ≈15; in most cases, clinician should examine patient, validate symptoms, and explain that antibiotics not needed; nonsteroidal anti-inflammatory drugs and acetaminophen may be prescribed; systemic decongestants associated with cardiovascular risks, but topical decongestants such as oxymetazoline (Afrin, Breaze, Equaline) may be used; risk for rhinitis medicamentosa low when oxymetazoline used for ≤5 days; topical corticosteroids may be used when clinician uncertain whether diagnosis URI or environmental allergy

Zinc for URI: zinc inhibits growth of viral and bacterial organisms; spray removed from market because of anosmia, but oral zinc safe; Cochrane analysis that included >1000 patients reported that zinc beneficial when started within 24 hr of onset of symptoms; zinc associated with 1 fewer day of symptoms and 75% reduction in use of antibiotics; although this paper withdrawn, another meta-analysis by Hemilä supported zinc lozenges and reported that zinc reduced duration of symptoms by 3 days; dose unknown; zinc may cause constipation and turn stool and tongue dark

Saline rinses for URI: neti pot safe and efficacious; however, tap water may contain amoeba such as Naegleria fowleri; patients should use boiled or distilled water

Warning signs in patients with URI: include high fever, altered mental status, difficulty breathing, diabetic ketoacidosis, and facial rash; patients should be examined

Antibiotics for URI: per IDSA, first-line treatment amoxicillin-clavulanic acid (Augmentin) for 1 wk; other choices doxycycline, levofloxacin, and moxifloxacin; many microbes resistant to azithromycin (Zithromax) and TMP-SMX; however, guidelines predate FDA warning (fluoroquinolones may be removed from list of recommended agents)

Recurrent infections: may herald problem with immune system; computed tomographic (CT) scan of sinuses has high negative predictive value, but sensitivity high (mucosal thickening may be unrelated to acute symptoms); if CT contemplated, clinician should refer patient to otolaryngologist to look for obstruction; recurrent infections may be associated with common variable immunodeficiency; random serum IgG used to make diagnosis; such patients may benefit from intravenous or subcutaneous IgG (Hizentra); clinician should rule out cystic fibrosis

C difficile: gram-positive rod and part of normal human colonic flora; mainly affects institutionalized and hospitalized patients, especially those ≥65 yr of age; spores resistant to drying, heat, ultraviolet light, and alcohol

Diagnosis of C difficile: test sensitive (false positives possible); symptoms include watery diarrhea in patient exposed to antibiotics; if test positive, clinician should consider clinical picture and severity of illness, looking for fever, abdominal pain, and frequent diarrhea; if diagnostic test available within few hours, clinician may wait to treat, but if C difficile suspected and results not available until following day, patient should be treated

Management of C difficile: antibiotics should be stopped; piperacillin-tazobactam (Zosyn) common offending agent; infected patients should be on advanced infection precautions (gowns, gloves, and hand hygiene with soap and water); loperamide (Imodium) and diphenoxylate-atropine (Lomotil) should not be used initially; for mild to moderate disease, if patient not septic or pregnant, metronidazole recommended; others treated with oral vancomycin; seriously ill patients may need admission to intensive care unit, rectal vancomycin, or intravenous metronidazole; vancomycin better drug for C difficile than metronidazole, but expensive and may promote growth of vancomycin-resistant enterococci

Recurrent C difficile: patients previously on metronidazole should receive vancomycin; for patient with second or third recurrence, treatments include pulsed vancomycin, long taper of vancomycin, or fecal transplant; fidaxomicin decreases risk for recurrent infection, but drug expensive; bezlotoxumab antibody to toxin made by C difficile, but expensive and may harm acutely ill patients; speaker recommends transplant from directed or community donor; efficacy of transplant greater than that of pharmacologic treatments; patients with recurrent C difficile should be referred to gastroenterologist familiar with transplant

Readings

Arroll B: Antibiotics for upper respiratory tract infections: an overview of Cochrane reviews. Respir Med 2005 Mar;99(3):255-61; Gágyor I et al: Ibuprofen versus fosfomycin for uncomplicated urinary tract infection in women: randomised controlled trial. BMJ 2015 Dec 23;351:h6544; Gupta K et al: Increasing antimicrobial resistance and the management of uncomplicated community-acquired urinary tract infections. Ann Intern Med 2001 Jul 3;135(1):41-50; Gupta K et al: International clinical practice guidelines for the treatment of acute uncomplicated cystitis and pyelonephritis in women: A 2010 update by the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases. Clin Infect Dis 2011 Mar 1;52(5):e103-20; Hemilä H: Zinc lozenges may shorten the duration of colds: a systematic review. Open Respir Med J 2011;5:51-8; Hooton TM et al: Cefpodoxime vs ciprofloxacin for short-course treatment of acute uncomplicated cystitis: a randomized trial. JAMA 2012 Feb 8;307(6):583-9; Hooton TM et al: Voided midstream urine culture and acute cystitis in premenopausal women. N Engl J Med 2013 Nov 14;369(20):1883-91; Little P et al: Effectiveness of five different approaches in management of urinary tract infection: randomised controlled trial. BMJ 2010 Feb 5;340:c199; Singh M, Das RR: Zinc for the common cold. Cochrane Database Syst Rev 2013 Jun 18;(6):CD001364.

Disclosures

For this program, members of the faculty and planning committee reported nothing to disclose. In his lecture, Dr. Pottinger presents information related to the off-label or investigational use of a therapy, product, or device.

Acknowledgements

Dr. Pottinger spoke at What’s New in Medicine 2017, presented by the Foundation for Care Management and What’s New in Medicine, and held September 8-9, 2017, in Kennewick, WA. To learn about meetings presented by the Foundation for Care Management and What’s New in Medicine, please visit fcmcme.org and whatsnewinmedicine.org. The Audio Digest Foundation thanks the speakers and the sponsors for their cooperation in the production of this program.

CME/CE INFO

Accreditation:

The Audio- Digest Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

The Audio- Digest Foundation designates this enduring material for a maximum of 0 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Audio Digest Foundation is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's (ANCC's) Commission on Accreditation. Audio Digest Foundation designates this activity for 0 CE contact hours.

Lecture ID:

IM652602

Expiration:

This CME course qualifies for AMA PRA Category 1 Credits™ for 3 years from the date of publication.

Instructions:

To earn CME/CE credit for this course, you must complete all the following components in the order recommended: (1) Review introductory course content, including Educational Objectives and Faculty/Planner Disclosures; (2) Listen to the audio program and review accompanying learning materials; (3) Complete posttest (only after completing Step 2) and earn a passing score of at least 80%. Taking the course Pretest and completing the Evaluation Survey are strongly recommended (but not mandatory) components of completing this CME/CE course.

Estimated time to complete this CME/CE course:

Approximately 2x the length of the recorded lecture to account for time spent studying accompanying learning materials and completing tests.