An Unusual Cause of Osteomyelitis

Dr Summiya Nizamuddin

• Sample received on 23.1.2010 from Multan• Pus aspirate sent for routine bacteriology• Male, 31 years• ‘Pus sample from finger’

Gram stain

–Pus cells: Numerous–Gram Negative Rods:

Rare–Gram Positive Cocci

(chains): Rare

• As per protocol, the swab was inoculated on to:–Chocolate agar–Blood Colistin Naladixic acid (BCNA) agar–MacConkey’s agar

• After 24 hours of incubation, growth suggestive of mixed oral flora

– Few alpha hemolytic colonies on chocolate and BCNA agar

– Few grayish tinged colonies on chocolate agar

– No growth on MacConkey’s agar

??? Pus from oral cavity

• The alpha hemolytic small colonies were isolated and identified

–Gram positive cocci in chains on gram’s stain–Catalase negative–Caramel like smell

–Most probably S. milleri

• The grayish colonies were found to be:

– Small, slender, straight GNR on gram’s stain–Oxidase positive– Catalase negative– Not growing on MacConkey’s agar– A bleachy odour was noted once the plates

were opened– Colonies were digging into

the agar

What sort of gram negative rods could these most probably be

Fastidious gram negative rods

Fastidious gram negative rods»catalase negative»oxidase positive»pits into the agar»smells of bleach

Brucella species

Cardiobacterium hominis

Kingella kingae

Moraxella catarrhalis

Neisseria species

Haemophilus influenzae

Capnocytophaga species

Eikenella corrodens

Brucella species

Cardiobacterium hominis

Kingella kingae

Moraxella catarrhalis

Neisseria species

Haemophilus influenzae

Capnocytophaga species

Eikenella corrodens

Brucella species

Cardiobacterium hominis

Kingella kingae

Moraxella catarrhalis

Neisseria species

Haemophilus influenzae

Eikenella corrodens

Cardiobacterium hominis

Kingella kingae

Eikenella corrodens

Something missing

History

• 31 year old male• Police Officer• Recent human bite history – approximately 1

month 10 days ago• Had seen many doctors because of recurrent

infections at the site of bite before being referred to a orthopedic surgeon in Multan

RapID™ NH System

RapID™ NH System

• 4 hour identification • Able to identify over 30 taxa based on

enzyme technology• Reagents impregnated wells In clear plastic

tray

At the end of four hours …

Eikenella corrodens with 99.9% accuracy

Reported as:• Streptococcus milleri• Sensitive to: Penicillin, Chloramphenicol, Ceftriaxone,

Clindamycin, Erythromycin, Ciprofloxacin

• Eikenella corrodens• Sensitive to: Co-amoxiclauv, Ampicillin, Ceftriaxone,

Ciprofloxacin, Tetracycline, Imipenem

Eikenella corrodens

• When first isolated in 1948, it was noted to pit or corrode the agar surface, producing colonies that grew in depressions, hence was called the corroding bacillus

• Previously known as Bacteroides corrodens

• Genus Eikenella belongs to the family of Neisseriaceae

• Only one species, E. corrodens has been recognized so far

• E. corrodens is a periodontopathogen that inhibits the human oral cavity, intestinal tract, and genital tract

• Are slender, straight, small, non motile, facultative anaerobic GNR

• Characterisitic feature: Colonies are 1 to 2mm in diameter after 48hrs of growth and show clear centers that are surrounded by spreading growth and they may pit the agar

• Smell of hypochlorite

• Fail to grow on most selective media

• Biochemically inactive, lacking oxidative and fermentative capabilities

• Fail to produce urease, indole, or hydrogen sulfide

• Are oxidase positive and most isolates are capable of reducing nitrate to nitrite

• Catalase is usually negative

• According to CLSI’s Approved Guideline for Abbreviated Identification:

“This is the only MacConkey-negative, catalase-negative, oxidase-positive, gram-negative rod that is ornithine positive”

• E. corrodens is generally regarded as an organism of low virulence

• Little is known about to the organism's virulence factors and it has a low level of pathogenicity for animals

• Like other HACEK bacteria, it is responsible for SBE

Eikenella corrodens also may be the cause of endocarditis, meningitis, brain abscesses, subdural empyema, septic arthritis, pneumonia, postsurgical infections, and soft-tissue diseases

• Therapeutic options beyond the“gold standard” penicillin:

• Broad spectrum beta-lactams (such as ceftriaxone, cefixime, meropenem and ampicillin/sulbactam), rifampin and the newer fluoroquinolones appear to be excellent choices

• Generally resistant to the first generation cephalosporins, oxacillin, aminoglycosides and the traditional antimicrobials active against anaerobes, such as clindamycin and metronidazole

In normal human hosts, Eikenella is usually involved in mixed bacterial infections, often with viridans group streptococci, and less frequently with Enterobacteriaceae

Most concomitant streptococcal isolates are members of the S. anginosis group, which consists of three species, S.anginous, S. constellatus and S. intermedius

Eikenella are also responsible for 7–29% of human hand-bite wound infections, as well as clenched-fist injuries, which are frequently complicated by bone resorption and osteomyelitis.

• Bilos, Z. J., A. Kucharchuk, and W. Metzger. 1978. Eikenella corrodens in human bites. Clin. Orthopaedics 134:320– 324.

• Goldstein, E. J. C., D. M. Citron, B. Wield, U. Blachman, V. L. Sutter, T. A. Miller, and S. M. Finegold. 1978a. Bacteriology of human and animal bite wounds. J. Clin. Microbiol. 8:667–672.

• Peeples, E., J. Boswick, and F. Scott. 1980. Wounds of the hand contaminated by human or animal saliva. J. Trauma 20:383–389.

• Brook, I. 1987. Microbiology of human and animal bite wounds in children. Ped. Infect. Dis. J. 6:29–32.

• A multicenter prospective study of 50 patients with infected human bites

• 56% of injuries were clenched-fist injuries and 44% were occlusional bites

• Median number of isolates per wound culture was 4 (3 aerobes and 1 anaerobe)

• Isolates included Streptococcus anginosus (52%), Staphylococcus aureus (30%), Eikenella corrodens (30%), Fusobacterium nucleatum (32%), and Prevotella melaninogenica (22%). Candida species were found in 8%.

Clinical Presentation and Bacteriologic Analysis of Infected Human Bites in Patients Presenting to Emergency DepartmentsClinical Infectious Diseases 2003; 37:1481–9

In IV drug abusers, E. corrodens endocarditis, osteomyelitis, and septicemia have been reported in association with the practice of licking needles or injection sites prior to drug inoculation

J Infect. 1994 Jan;28(1):102-3. Eikinella corrodens septicaemia among drug injectors: a possible association with

'licking wounds'

A 65-year-old man from Indonesia developed slowly progressive vertebral collapse and worsening neck pain. History suggested a previous pharyngeal injury while eating fish.

Cultures grew out E. corrodens as the causative organism of this patient's osteomyelitis.

Spine. 2000 May 1;25(9):1185-7.Eikenella corrodens vertebral osteomyelitis secondary to direct inoculation: a case report

E. corrodens has been reported as the causative agent of infections at many sites, largely secondary to contamination with oral secretions.

E. corrodens osteomyelitis in a young woman, that resulted from puncture of her foot with a toothpick which had apparently been used.

Infection. 2000 Sep;28(5):332-3.Tale of a toothpick: Eikenella corrodens osteomyelitis

Severe cellulitis and septic arthritis due to E. corrodens and a viridans group streptococcus developed following dental manipulation in a patient with a history of hemarthrosis.

Isolation of E. corrodens on a culture of a knee aspirate. Antimicrobial (ampicillin) therapy resulted in a therapeutic response.

J Clin Microbiol. 1989 Nov;27(11):2606-8. Eikenella corrodens cellulitis and arthritis of the knee

Take home message:

• Knowledge of the spectrum of microorganisms present in the oral cavity and their antibiotic sensitivity is important for guiding empiric therapy

• The laboratory should also be notified when oral flora are suspected to enable the optimum isolation of causative organisms

Thank you