Peer Reviewed

Case in Point

Urethritis Caused by Nontypeable Haemophilus influenzae

Authors:
Ruijing Liang, DO
Rotating Intern, Peconic Bay Medical Center, Riverhead, New York

Kamal Singh, MD
Chief of Pediatrics, Peconic Bay Medical Center, Riverhead, New York, and Assistant Professor of Pediatrics, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York

Sandeep A. Gandhi, MD
Infectious Diseases Consultant at Peconic Bay Medical Center, Riverhead, New York, and Associate Professor of Clinical Medicine, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York

Citation:
Liang R, Singh K, Gandhi SA. Urethritis caused by nontypeable Haemophilus influenzae [published online March 26, 2019]. Infectious Diseases Consultant.

 

A 19-year-old man presented with a 1-week history of milky white urethral discharge. He denied any fever, dysuria, or lymphadenopathy, and the results of a review of systems were otherwise unremarkable. He had multiple female sexual partners and engaged in oral sex. He denied any recent travel or zoonotic exposure. His medical history was significant for 2 episodes of urethritis caused by Chlamydia trachomatis that had been treated with azithromycin.

At presentation, his vital signs were stable. The penile shaft was without any lesions. There were no palpable inguinal lymph nodes or epididymal tenderness. A milky white secretion could be expressed from the penile meatus. The rest of the physical examination findings were normal.

Results of a nucleic acid amplification test (NAAT) of the urine and urethral discharge were negative for Neisseria gonorrhoeae and C trachomatis. Results of an HIV antibody test and a syphilis rapid plasma reagin test were negative. However, bacterial culture of the urethral discharge grew nontypeable Haemophilus influenzae.

The patient was treated with azithromycin, leading to complete resolution of his symptoms.

Discussion. Common pathogens causing urethritis include C trachomatis, N gonorrhoeae, Mycoplasma genitalium, and Trichomonas vaginalis.1 Herpes simplex virus, adenovirus and H influenzae also can be pathogens in urethritis.2

H influenzae is an obligate human commensal organism that usually colonizes the human respiratory tract and is transmitted via respiratory droplets. They are nonmotile, gram-negative rods that facultatively anaerobic with immunoglobulin A protease as a virulence factor to invade respiratory mucosa.3

The 2 strains of H influenzae, encapsulated and nonencapsulated, can cause serious childhood infections including meningitis and epiglottitis, but the capsulated H influenzae type b is now rare due to a vaccine. The nontypeable strains often cause otitis media in young children. In immunocompromised individuals such as those with chronic obstructive pulmonary disease or HIV infection, they can also cause other respiratory diseases including sinusitis, bronchitis, and pneumonia.4 Individuals with a history of smoking, alcoholism, cystic fibrosis, underlying malignancy, or any pulmonary insult have a higher risk of contracting infection with both strains of H influenzae.

The diagnosis is often made clinically. NAAT can provides a fast and accurate result.5

In the pediatric population, the H influenzae vaccine is given at 2, 4, 6, and 12-15 months of age. For infections caused by H influenzae in adults, second- or third-generation cephalosporins are usually prescribed instead of amoxicillin due to increasingly resistant strains.6 Fluoroquinolones, azithromycin, and clarithromycin can also be used for treatment.

Predicting the microorganisms that cause nongonococcal urethritis in men is difficult.7 This patient’s case is unusual because H influenzae, a common respiratory tract organism, was found in the urethral discharge. If results of NAAT of urine and urethral discharge are negative, bacterial culture should also be obtained to find the causative pathogen.

In conclusion, H influenzae should be considered as a diagnosis in a person with nongonococcal urethritis that does not respond to doxycycline.

References:

  1. Gaydos C, Maldeis NE, Hardick A, Hardick J, Quinn TC. Mycoplasma genitalium compared to chlamydia, gonorrhoea and trichomonas as an aetiological agent of urethritis in men attending STD clinics. Sex Transm Infect. 2009;85(6):438-440.
  2. Ito S, Hatazaki K, Shimuta K, et al. Haemophilus influenzae isolated from men with acute urethritis: its pathogenic roles, responses to antimicrobial chemotherapies, and antimicrobial susceptibilities. Sex Transm Dis. 2017;44(4):205-210.
  3. Haemophilus, Bordetella, and Legionella. In: Gladwin M, Trattler B, Mahan CS. Clinical Microbiology Made Ridiculously Simple. 6th ed. Miami, FL: MedMaster Books; 2016:chap 11.
  4. Haemophilus influenzae disease (including Hib). Centers for Disease Control and Prevention. https://www.cdc.gov/hi-disease/clinicians.html. Reviewed February 13, 2018. Accessed March 26, 2019.
  5. Gaydos CA, Van Der Pol B, Jett-Goheen M, et al. 2013. Performance of the Cepheid CT/NG Xpert Rapid PCR test for detection of Chlamydia trachomatis and Neisseria gonorrhoeae. J Clin Microbiol. 2013;51(6):1666-1672.
  6. Deguchi T, Ito S, Hatazaki K, et al. Antimicrobial susceptibility of Haemophilus influenzae strains isolated from the urethra of men with acute urethritis and/or epididymitis. J Infect Chemother. 2017;23(11):804-807.
  7. Ito S, Hanaoka N, Shimuta K, et al. Male non-gonococcal urethritis: from microbiological etiologies to demographic and clinical features. Int J Urol. 2016;23(4):325-331.