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Haemophilus Influenzae Infections Medication

  • Author: Vidya R Devarajan, MD; Chief Editor: Pranatharthi Haran Chandrasekar, MBBS, MD  more...
Updated: Feb 16, 2016

Medication Summary

Initially, patients with invasive and serious H influenzae infections are best treated with an intravenous third-generation cephalosporin.



Class Summary

Therapy must be comprehensive and cover all likely pathogens in the context of this clinical setting. Penicillins are useful in management of mucosal infections caused by nonencapsulated H influenzae. As many as 25-50% of isolates produce beta-lactamase; therefore, they are resistant to this class of drugs. Third-generation cephalosporins are highly effective in H influenzae infections. Meropenem or ampicillin and chloramphenicol are alternative regimens.

Azithromycin (Zithromax)


Acts by binding to 50S ribosomal subunit of susceptible microorganisms and blocks dissociation of peptidyl tRNA from ribosomes, causing RNA-dependent protein synthesis to arrest. Nucleic acid synthesis is not affected.

Concentrates in phagocytes and fibroblasts as demonstrated by in vitro incubation techniques. In vivo studies suggest that concentration in phagocytes may contribute to drug distribution to inflamed tissues.

Treats mild-to-moderate microbial infections.

Plasma concentrations are very low, but tissue concentrations are much higher, giving it value in treating intracellular organisms. Has a long tissue half-life.

Cefotaxime (Claforan)


Third-generation cephalosporin with gram-negative spectrum. Lower efficacy against gram-positive organisms.

Ceftriaxone (Rocephin)


Third-generation cephalosporin with broad-spectrum, gram-negative activity; lower efficacy against gram-positive organisms; higher efficacy against resistant organisms; arrests bacterial growth by binding to one or more penicillin-binding proteins. Exerts antimicrobial effect by interfering with synthesis of peptidoglycan, a major structural component of bacterial cell wall. Bacteria eventually lyse because of the ongoing activity of cell wall autolytic enzymes while cell wall assembly is arrested. Highly stable in presence of beta-lactamases, both penicillinase and cephalosporinase, of gram-negative and gram-positive bacteria. Approximately 33-67% of dose excreted unchanged in urine, and remainder secreted in bile and, ultimately, in feces as microbiologically inactive compounds. Reversibly binds to human plasma proteins, and binding has been reported to decrease from 95% bound at plasma concentrations < 25 mcg/mL to 85% bound at 300 mcg/mL.

Cefuroxime (Ceftin, Zinacef)


This second-generation cephalosporin maintains gram-positive activity of first-generation cephalosporins; adds activity against Proteus mirabilis, H influenzae, Escherichia coli, Klebsiella pneumoniae, and Moraxella catarrhalis. Binds to penicillin-binding proteins and inhibits final transpeptidation step of peptidoglycan synthesis, resulting in cell wall death. It is not recommended for treatment of Hib meningitis but may be used for other Hib infections. Condition of patient, severity of infection, and susceptibility of microorganism determine proper dose and route of administration.

Ampicillin (Marcillin, Omnipen, Polycillin, Principen)


Broad-spectrum penicillin. Interferes with bacterial cell wall synthesis during active replication, causing bactericidal activity against susceptible organisms. Alternative to amoxicillin when unable to take PO medication.

Amoxicillin (Trimox, Amoxil, Trimox)


Derivative of ampicillin and has similar antibacterial spectrum, namely certain gram-positive and gram-negative organisms. Superior bioavailability and stability to gastric acid and has broader spectrum of activity than penicillin. Somewhat less active than that of penicillin against pneumococcus. Penicillin-resistant strains also resistant to amoxicillin, but higher doses may be effective. More effective against gram-negative organisms (eg, Neisseria meningitidis, H influenzae) than penicillin. Interferes with synthesis of cell wall mucopeptides during active multiplication, resulting in bactericidal activity against susceptible bacteria.

Amoxicillin and clavulanic acid (Augmentin)


Amoxicillin inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins. Addition of clavulanate inhibits beta-lactamase–producing bacteria. Good alternative antibiotic for patients allergic or intolerant to the macrolide class. Is usually well tolerated and provides good coverage to most infectious agents. Not effective against Mycoplasma and Legionella species. The half-life of oral dosage form is 1-1.3 h. Has good tissue penetration but does not enter CSF. For children >3 months, base dosing protocol on amoxicillin content. Because of different amoxicillin/clavulanic acid ratios in 250-mg tab (250/125) vs 250-mg chewable tab (250/62.5), do not use 250-mg tab until child weighs >40 kg. The bid dosing schedule reduces incidence of diarrhea.

Chloramphenicol (Chloromycetin)


May be used in patients who are allergic to penicillins and cephalosporins. Binds to 50S bacterial-ribosomal subunits and inhibits bacterial growth by inhibiting protein synthesis. Active in vitro against a wide variety of bacteria, including gram-positive, gram-negative, aerobic, and anaerobic organisms. Well-absorbed from GI tract and metabolized in the liver, where it is inactivated by conjugation with glucuronic acid and then excreted by the kidneys. Oral form is not available in the United States.

Erythromycin and sulfisoxazole (Eryzole, Pediazole)


Erythromycin is a macrolide antibiotic with a large spectrum of activity. Erythromycin binds to the 50S ribosomal subunit of the bacteria, which inhibits protein synthesis. Sulfisoxazole expands erythromycin's coverage to include gram-negative bacteria. Sulfisoxazole inhibits bacterial synthesis of dihydrofolic acid by competing with para-aminobenzoic acid. Good choice for PO therapy for otitis media. May be used in patients who are allergic to penicillins and cephalosporins.

Meropenem (Merrem IV)


Bactericidal broad-spectrum carbapenem antibiotic that inhibits cell-wall synthesis. Effective against most gram-positive and gram-negative bacteria. Has slightly increased activity against gram-negative species and slightly decreased activity against staphylococci and streptococci compared with imipenem. In contrast to imipenem, indicated for treatment of bacterial meningitis, including pediatric meningitis.

Rifampin (Rifadin)


Used for chemoprophylaxis in Hib infections.



Class Summary

These agents are used as adjunctive therapy in H influenza meningitis for the anti-inflammatory effects and prevention of sensorineural deafness. Administer before or with antibiotics, not after. Utility of steroids has been demonstrated primarily in nonimmunized children, and its usefulness in adults or vaccinated children is not known.

Dexamethasone (Decadron, Baldex)


Has many pharmacologic benefits but significant adverse effects. Stabilizes cell and lysosomal membranes, increases surfactant synthesis, increases serum vitamin A concentration, and inhibits prostaglandin and proinflammatory cytokines (eg, TNF-alpha, IL-6, IL-2, and IFN-gamma). The inhibition of chemotactic factors and factors that increase capillary permeability inhibits recruitment of inflammatory cells into affected areas. Suppresses lymphocyte proliferation through direct cytolysis and inhibits mitosis. Breaks down granulocyte aggregates and improves pulmonary microcirculation.

Adverse effects are hyperglycemia, hypertension, weight loss, GI bleeding or perforation synthesis, cerebral palsy, adrenal suppression, and death. Most of the adverse effects of corticosteroids are dose-dependent or duration-dependent.

Readily absorbed via the GI tract and metabolized in the liver. Inactive metabolites are excreted via the kidneys. Lacks salt-retaining property of hydrocortisone.

Patients can be switched from an IV to PO regimen in a 1:1 ratio.

Contributor Information and Disclosures

Vidya R Devarajan, MD 

Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Charles V Sanders, MD Edgar Hull Professor and Chairman, Department of Internal Medicine, Professor of Microbiology, Immunology and Parasitology, Louisiana State University School of Medicine at New Orleans; Medical Director, Medicine Hospital Center, Charity Hospital and Medical Center of Louisiana at New Orleans; Consulting Staff, Ochsner Medical Center

Charles V Sanders, MD is a member of the following medical societies: American College of Physicians, Alliance for the Prudent Use of Antibiotics, The Foundation for AIDS Research, Southern Society for Clinical Investigation, Southwestern Association of Clinical Microbiology, Association of Professors of Medicine, Association for Professionals in Infection Control and Epidemiology, American Clinical and Climatological Association, Infectious Disease Society for Obstetrics and Gynecology, Orleans Parish Medical Society, Southeastern Clinical Club, American Association for the Advancement of Science, Alpha Omega Alpha, American Association of University Professors, American Association for Physician Leadership, American Federation for Medical Research, American Geriatrics Society, American Lung Association, American Medical Association, American Society for Microbiology, American Thoracic Society, American Venereal Disease Association, Association of American Medical Colleges, Association of American Physicians, Infectious Diseases Society of America, Louisiana State Medical Society, Royal Society of Medicine, Sigma Xi, Society of General Internal Medicine, Southern Medical Association

Disclosure: Received royalty from Baxter International for other.

Chief Editor

Pranatharthi Haran Chandrasekar, MBBS, MD Professor, Chief of Infectious Disease, Program Director of Infectious Disease Fellowship, Department of Internal Medicine, Wayne State University School of Medicine

Pranatharthi Haran Chandrasekar, MBBS, MD is a member of the following medical societies: American College of Physicians, American Society for Microbiology, International Immunocompromised Host Society, Infectious Diseases Society of America

Disclosure: Nothing to disclose.


Wesley W Emmons, MD, FACP Assistant Professor, Department of Medicine, Thomas Jefferson University; Consulting Staff, Infectious Diseases Section, Department of Internal Medicine, Christiana Care, Newark, DE

Wesley W Emmons, MD, FACP is a member of the following medical societies: American College of Physicians, American Medical Association, American Society of Tropical Medicine and Hygiene, Infectious Diseases Society of America, and International AIDS Society

Disclosure: Nothing to disclose.

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