Doctors in Denmark have reported a rare case of meningitis caused by a bacterial infection most likely picked up from a horse.
The 73-year-old man was diagnosed as suffering from meningitis caused by the zooepidemicus subspecies of Streptococcus equi.
Streptococcus zooepidemicus is among the normal bacterial flora found in horses. It can be found in equine wound infections, and has been isolated from other mammals such as cows, rabbits, and swine. In some cases, zooepidemicus has been isolated from humans through throat swabs.
It occasionally causes human infection, including sinusitis, endocarditis, septic arthritis and osteomyelitis, that can be traced back to contact with horses or consumption of unpasteurized dairy products.
It is a rare cause of meningitis in humans, with only 27 previously published adult cases in the literature, according to the Danish doctors.
The scientists, in a case report published in BMC Research Notes, said the patient showed clinical signs of meningitis when admitted to a neurological intensive care unit. He had fever, headache, neck stiffness, drowsiness and general malaise.
Testing revealed S. zooepidemicus as the cause of his meningitis.
He had recently cared for a sick horse with an upper respiratory tract infection, the description of which was consistent with a case of strangles, they said.
The patient responded well to an antibiotic and antiviral regime, they reported, but suffered some sight impairment in his left eye as a result of the infection.
“The most probable source of infection was the close contact to an infected horse,” the doctors said. “It is likely that the streptococci primarily infested the airways and disseminated via the bloodstream into the meninges and the left eye.”
The sight impairment resulted from endogenous endophthalmitis. The doctors said the case constituted the third description of endogenous endophthalmitis as a complication in meningitis caused by S. zooepidemicus. Overall, it was generally considered a very rare complication of meningitis.
However, the doctors noted that it had now been reported in 10.7 percent of all published S. zooepidemicus meningitis cases.
“This may suggest it could occur more frequently in S. zooepidemicus meningitis than in meningitis caused by other microorganisms such as Streptococcus pneumoniae or Neisseria meningitidis.”
Endogenous endophthalmitis complicating Streptococcus equi subspecies zooepidemicus meningitis: a case report
Dominik Madžar, Mareike Hagge, Sebastian Möller, Martin Regensburger, De-Hyung Lee,
Stefan Schwab, and Jonathan Jantsch.
BMC Research Notes (2015) 8:184 doi:10.1186/s13104-015-1133-9
The case report can be read here.