Microbiology Case Study: A 33 Year Old Female with Abdominal Pain

Case History:

A 33 year old African American female presents to the hospital complaining of mild abdominal pain for the past couple of days. She is 17 weeks pregnant and has a history of two prior spontaneous abortions at 15 and 16 weeks due to a shortened cervix. She is afebrile and denies any vaginal bleeding or leakage of amniotic fluid. A complete blood count reveals mild leukocytosis and anemia. On physical examination, her cervix is 2 cm dilated with bulging membranes. She is admitted for a possible cerclage placement, and an amniocentesis is performed to rule out infection prior to the procedure. The microbiology lab received 20 ml of clear, amber fluid for Gram stain and bacterial culture.

fuso1
Figure 1. Direct Gram stain from the amniotic fluid showing many neutrophils and fusiform Gram negative bacilli (1000x oil immersion).
fuso2
Figure 2. Wright-Geimsa stain of the amniotic fluid specimen containing many acute inflammatory cells which have engulfed the fusiform bacteria (1000x oil immersion).
fuso3
Figure 3. Small, greyish-white colonies growing on Brucella blood agar after 48 hours of incubation under anaerobic conditions at 35°C.

Laboratory Identification:

The Gram stain showed moderate fusiform Gram negative bacilli in a background of many acute inflammatory white blood cells. Bacterial cultures grew small, greyish-white colonies as Brucella blood agar and routine blood agar after 48 hours of incubation under anaerobic conditions at 35°C. No growth was observed on kanamycin-vancomycin laked blood (KVLB) agar. The organism was identified by MALDI-TOF as Fusobacterium nucleatum and confirmed using the Vitek anaerobic identification card.

Discussion:

Fusobacterium nucleatum is an anaerobic, Gram-negative rod that is non-spore forming. It is considered normal flora of the oral cavity and gastrointestinal & genitourinary tracts of healthy adults. F. nucleatum has been implicated in the pathogenesis of oropharyngeal infections, especially in neutropenic patients with mucositis after receiving chemotherapy or bone marrow transplant. It is an important etiologic agent in a wide spectrum of extraoral infections including bacteremia, brain abscess, osteomyelitis and infections of the genitorurinary tract, including the fetal membranes. There have been many documented cases linking infections with F. nucleatum to chorioamnionitis, preterm birth, and neonatal sepsis. The mode of transmission of F. nucleatum to the amniotic fluid can be as a result of direct extension from the vaginal tract, hematogenous spread or as recently implicated, orogenital transmission.

Given that F. nucleatum is the most common of Fusobacterium species found in clinical specimens and it’s potential to cause significant disease, early identification of the pathogen is important. It grows well on a non-selective anaerobic agar and its growth is inhibited on Bacteroides bile esculin (BBE) and kanamycin-vancomycin laked blood (KVLB) agars. After 48 hours of incubation under anaerobic conditions, the colonies measure 1-2 mm in diameter and have been noted to have a characteristic internal flecking quality that is referred to as “speckled opalescence”. On Gram stain, the fusiform cells of F. nucleatum are long (usually 5-10 µm in length), slender filaments with tapered ends and may contain spherical swellings. In regards to biochemical testing, it is indole positive and lipase negative. Disk testing for Fusobacterium spp. shows the bacteria are resistant to vancomycin and susceptible to kanamycin and colistin.

While susceptibility testing is not routinely performed for all anaerobes, testing is indicated for organisms in pure culture isolated from normally sterile sites or for those more virulent organisms for which susceptibilities cannot be predicted. In the case of Fusobacterium spp., penicillin and ampicillin resistance among isolates of has been reported due to beta-lactamase production and it is recommended that all Gram negative anaerobes have a beta-lactamase screen performed. F. nucleatum is routinely susceptible to metronidazole, clindamycin and beta-lactam beta-lactamase inhibitor combination antibiotics.

In the case of our patient, her diagnosis of F. nucleatum in the amniotic fluid specimen precluded her from obtaining a rescue cerclage procedure. She was transferred to labor and delivery for a uterine evacuation secondary to the intra-amniotic infection and delivered a non-viable fetus. She received ampicillin and gentamicin as intravenous antibiotics.

 

sims

-Brooke Sims, MD, is a third year Anatomic and Clinical Pathology resident at the University of Mississippi Medical Center.

Stempak

-Lisa Stempak, MD, is an Assistant Professor of Pathology at the University of Mississippi Medical Center in Jackson, MS. Currently, she oversees testing performed in both the Chemistry and Microbiology Laboratories.

 

Microbiology Case Study: Young Girl with Community-Acquired Pneumonia

A young girl presented to the emergency department with 6 days of cough, congestion, and intermittent fever up to 102°F. Respiratory viral testing, blood cultures, and a chest x-ray were ordered. The patient was found to be RSV positive and sent home with oral steroids. Two days later she presented the emergency department once again with worsening respiratory symptoms and a positive blood culture with the following organism (Figure 1).

streppneu1
Figure 1. Gram stain demonstrating Gram-positive cocci in pairs and chains.

Our patient developed a Streptococcus pneumoniae superinfection and bacteremia in conjunction with RSV pneumonia.

Identification

S. pneumoniae is a Gram-positive cocci that forms “lancet” shaped pairs on Gram stain (Figure 1). Due to pretreatment with antibiotics, our Gram stain shows some pairs, but many Gram variable chains of cocci as well. S. pneumoniae grows as alpha hemolytic colonies on 5% sheep blood, chocolate, and CAN (colistin nalidixic acid) agar in 12-18 hours, where it forms umbelicated colonies with a characteristic navel-like depression in the middle due to autolysins produced by the bacterium. Some serotypes of S. pneumoniae, primarily serotype 3, have a mucoid phenotype seen in Figure 3. S. pneumoniae is a member of the Streptococcus mitis group, but due to its pathogenic potential it has always been singled out. This is accomplished using two biochemical tests: bile solubility testing with 10% deoxycholate, which dissolves colonies of S. pneumoniae but not those of other Viridans group streptococci, and optochin disc testing, to which S. pneumoniae is sensitive while other Virdians group streptococci are resistant (Figures 2 and 3). Many molecular assays have trouble differentiating S. pneumoniae from S. mitis group due to their similarities on a nucleotide and protein level, so biochemical testing is still a mainstay of organism identification.

streppneu2
Figure 2. Growth of α-hemolytic bacterial colonies on 5% sheep blood agar. Zone around the disc indicates the organism is optochin susceptible.

 

streppneu3
Figure 3. Growth of mucoid, α-hemolytic bacterial colonies on 5% sheep blood agar. The mucoid colony morphology suggests this isolate is likely serotype 3.

Clinical Significance

S. pneumoniae is known to cause a variety of clinical manifestations in children, from community acquired pneumonia and acute otitis media to bacteremia and meningitis. S. pneumoniae is also a colonizer of the upper respiratory tract; approximately 21% of children in developed countries and 90% of children in developing countries are asymptotically colonized. Due to the high rates of S. pneumoniae colonization in children, direct urine antigen testing is inappropriate, as it cannot distinguish asymptomatic carriage from invasive disease. S. pneumoniae direct antigen detection from CSF has been shown to have < 30% sensitivity and offers no benefit over a routine cytospin Gram stain.

Vaccination in children

Around 2000 the first S. pneumoniae vaccine became available. PCV7 was a heptavalent conjugate vaccine which provided protection from the 7 most common S. pneumoniae serotypes known to cause invasive disease (4, 6B, 9V, 14, 18C, 19F, and 23F). Routine vaccination of children was a huge success which reduced the incidence of invasive pneumococcal disease attributed to vaccine strains by 99%. An indirect benefit of the PCV7 vaccine was that adults >65 years of age saw a 92% decrease in invasive pneumococcal disease caused by PCV7 serotypes, despite not being vaccinated themselves, because of reduced transmission of S. pneumoniae from children to adults. Due to the selective pressure of the vaccine, non-vaccine serotypes of S. pneumoniae such as 19A subsequently became the predominant causes of invasive streptococcal disease. In 2010, a 13-valent pneumococcal conjugate vaccine (PCV13) was FDA approved. It includes all seven S. pneumoniae serotypes contained in PCV7, plus six additional serotypes (1, 3, 5, 6A, 7F, and 19A). PCV13 provides coverage against 2/3 of all serotypes responsible for invasive pneumococcal disease in children under 5 years of age.

Follow up

The patient had an uneventful hospital stay. All subsequent blood cultures were negative and susceptibility testing found the patient’s S. pneumoniae isolate to be susceptible to penicillin, cefotaxime, and clindamycin. The patient and was discharged home after 24 hours of observation with a 7 day course of amoxicillin.

 

References:

  • Manual of Clinical Microbiology, 11th edition
  • Pediatric Red Book, 2015 Report of the Committee on Infectious Diseases, 30th edition

 

-Erin McElvania TeKippe, Ph.D., D(ABMM), is the Director of Clinical Microbiology at Children’s Medical Center in Dallas Texas and an Assistant Professor of Pathology and Pediatrics at University of Texas Southwestern Medical Center.

Microbiology Case Study: 45 Year Old Woman with Subarachnoid Hemorrhage

Case History:

A 45 year-old woman was hospitalized for a bilateral subarachnoid hemorrhage with right-sided intraventricular hemorrhage secondary to a basilar artery aneurysm. On hospital day 2, after endovascular coiling of her aneurysm, she developed seizure-like activity. She was found to have new bilateral thalamic and brainstem infarcts with increased hydrocephalus and had an external ventricular drain placed.

She showed some minimal neurological improvements over the next 2 weeks until hospital day 17 when her mental status acutely declined and she developed a fever, leukocytosis, and meningeal signs. 8cc of cloudy, yellow fluid was collected via lumbar puncture. Analysis of the fluid showed pleocytosis (cell count of 54K) with a neutrophil predominance and markedly elevated protein.

CSF Gram stain
CSF Gram stain
CSF Gram stain
CSF Gram stain
CSF aerobic culture on blood agar
CSF aerobic culture on blood agar
CSF aerobic culture on MacConkey
CSF aerobic culture on MacConkey

Laboratory Identification:

Initial review of the spinal fluid gram stain showed many polymorphonuclear leukocytes and what appeared to be paired gram negative cocci suspicious for Neisseria meningitidis. However, many organisms lacked the more characteristic “kidney-bean” shape. Further inspection of the gram stain revealed many gram negative organisms which more closely resembled bacilli. Given the patient’s history and clinical course, it was determined the pathological agent was most likely a gram negative coccobacillus. On culture, the bacteria formed smooth, round, opaque colonies on Blood and Chocolate agar and was lactose non-fermenting on MacConkey agar. The bacterial colonies were also oxidase negative.

Mass spectrometry identified the organism as Acinetobacter radioresistens.

Rare gram positive appearing organisms of similar shape were also located on the gram stain. This demonstrates that Acinetobacter is known to occasionally retain the crystal violet stain leading to cases of initial misidentification.

Discussion:

Acinetobacter radioresistens is one of about 30 species of bacteria included in the Acinetobacter genus. Acinetobacter is characterized as a gram negative, aerobic coccobacillus which is non-motile, non-fermentative, and oxidase-negative. It grows well on standard aerobic media and typically forms smooth, round, mucoid colonies at 37°C. Acinetobacter is a water organism which preferentially colonizes aquatic, humid, and tropical environments; perhaps accounting for the increased incidence of Acinetobacter infections between the months of July and October.

While there have been reported cases of community-acquired Acinetobacter pneumonia in Southeast Asia and Australia, in most areas of the world Acinetobacter is known primarily as an agent of nosocomial infections. Studies show that an estimated 33% of healthcare workers are colonized with Acinetobacter and that it is one of the most prevalent bacteria isolated from the white coats of medical students. Despite its ubiquity in hospitals, Acinetobacter infections are relatively rare. Many patients may be colonized with it, but Acinetobacter only usually causes disease in immunocompromised and/or critically-ill patients with long hospitalizations. At particular risk are ventilated patients supported with multiple lines, drains, and catheters. Acinetobacter is reported as the pathological agent in a small percent of ventilator-associated pneumonias, central line-associated bloodstream infections, catheter-associated urinary tract infections, and surgical site infections. It is also recognized as a cause of nosocomial meningitis in neurosurgical patients with external ventricular drains, especially those with a history of intracranial hemorrhage and recent prior antibiotic therapy.

Acinetobacter infections are of particular concern because several species demonstrate resistance to many antimicrobials. Acinetobacter baumanni, the species responsible for the majority of Acinetobacter infections, has demonstrated resistance to 1st-3rd generation cephalosporins, macrolides, penicillins, and aminoglycosides. Because these infections are robust and difficult to treat, patients with Acinetobacter infections have a 25-75% mortality risk depending on the site of their infection and their baseline cardiopulmonary and immune status. Currently, carbapenems are considered the gold standard treatment.

-Elaine Amoresano, MD, is a 1st year anatomic and clinical pathology resident at the University of Vermont Medical Center.

 

Wojewoda-small

-Christi Wojewoda, MD, is the Director of Clinical Microbiology at the University of Vermont Medical Center and an Assistant Professor at the University of Vermont.

 

Microbiology Case Study: Immunocompromised 65 Year Old Man

Case History:

A 65 year old man presents to the emergency room with acute onset back pain. Of note, the man was diagnosed with Burkitt’s lymphoma two months prior and had recently received a course of chemotherapy. During the workup for his back pain, a chest CT is obtained and reveals a 2 cm pulmonary nodule in the left upper lobe with a surrounding “groundglass halo” highly suspicious for invasive fungal involvement. A fine needle aspiration (FNA) of the nodule is performed and tissue is sent for histopathologic examination as well as bacterial and fungal culture.

Chest CT showing a 2 cm nodule in the left upper lobe
Chest CT showing a 2 cm nodule in the left upper lobe
Silver stain of the FNA specimen showing ribbon-like fungal elements with rare septations
Silver stain of the FNA specimen showing ribbon-like fungal elements with rare septations
Scotch-tape preparation reveals rarely septate hyphae with internodal rhizoids and pyriform sporangia supported by funnel-shaped apophyses.
Scotch-tape preparation reveals rarely septate hyphae with internodal rhizoids and pyriform sporangia supported by funnel-shaped apophyses.
Scotch-tape preparation reveals rarely septate hyphae with internodal rhizoids and pyriform sporangia supported by funnel-shaped apophyses.
Scotch-tape preparation reveals rarely septate hyphae with internodal rhizoids and pyriform sporangia supported by funnel-shaped apophyses.

 

Laboratory Identification:

One rapidly growing white colony was identified that became grey over time. The colony was a “lid-lifter” that began pushing at the lid after only a few days. Microscopically, the organisms had broad hyphae with single and branching sporangiophores. At the ends of the sporangiophores there were pyriform, or pear-shaped, sporangia sitting atop funnel-shaped apophyses. Rhizoids were found to be internodal, or arising from the hyphae between the sporangiophores. Based on this morphology, the fungal organisms were identified as Lichtheimia corymbifera complex (formally Absidia corymbifera).

Discussion:

Lichtheimia corymbifera is an organism within the phylum Zygomycota and is one of two pathogenic species in the genus Lichtheimia. This organism is known as an uncommon cause of Zygomycosis and is only implicated in approximately 5% of cases. As in most cases of Zygomycosis, exemplified in our patient, Lichtheimia corymbifera most often affects immunocompromised patients. It is ubiquitous in the environment and is associated with decaying plant matter and soil. Disease is caused by inhalation of spores.

Important points for laboratory identification:

Lichtheimia

  • Growth at 35-37°C (capable of growth up to 50°C)
  • Inhibited by media containing cycloheximide
  • Internodal rhizoids
  • Pyriform sporangia
  • Apophysis

Compared to other common Zygomycetes:

Mucor

  • No rhizoids
  • Round sporangia
  • No apophysis

Rhizopus

  • Nodal rhizoids (directly opposite of the sporangiophores)
  • Round sporangia
  • No apophysis

 

-Britni Bryant, MD is a 2nd year anatomic and clinical pathology resident at the University of Vermont Medical Center.

 

Wojewoda-small

-Christi Wojewoda, MD, is the Director of Clinical Microbiology at the University of Vermont Medical Center and an Assistant Professor at the University of Vermont.

Microbiology Case Study: 4 Year Old Girl with Diarrhea

A 4-year-old girl with no past medical history had been feeling unwell for one day following a barbecue she had attended a few days prior. Her symptoms worsened to include colicky abdominal pain and bloody diarrhea, with as many as eight bowel movements per day. This persisted for the following two days; thereafter, she presented to the hospital also complaining of fever, nausea, and vomiting. She was found to be dehydrated and pale on exam, and was admitted for intravenous rehydration. Fecal leukocyte testing and stool cultures were sent. A Gram stain of the pathogen isolated from stool culture is shown in Figure 1.

camp1
Figure 1. Gram stain showing Gram-negative, curved rods

An infectious etiology is highly suspected given this patient’s presentation, leading to work-up with fecal leukocytes and stool cultures. The presence of fecal leukocytes, which was positive in this patient, is a strong indicator of inflammatory diarrhea. Bacterial stool culture allows for detection of Salmonella, Shigella, Campylobacter, E. coli O157:H7, Yersinia, Aeromonas, and Plesiomonas.

Many different culture mediums are used to isolate bacterial gastrointestinal pathogens. In addition to the routine 5% sheep blood agar and MacConkey agar, a case of infectious diarrhea requires further workup to rule out the above mentioned pathogens. Sorbitol-MacConkey agar is a variant of traditional MacConkey agar, and is used to detect E. Coli O157:H7, which differs from other E. coli strains by its inability to ferment sorbitol, thus forming colorless colonies on this media. Xylose lysine deoxycholate (XLD) and hektoen enteric (HE) agars are utilized for the selection and differentiation between Salmonella and Shigella. A sweep of bacteria growing on the blood agar plate and subsequent oxidase testing is used for detection of Aeromonas and Plesiomonas, which are oxidase positive organisms unlike normal fecal flora which is oxidase negative. Cefsulodin-irgasan-novobiocin (CIN) agar is used for the selection and differentiation of Yersinia, which utilizes inhibitory substances (cefsulodin, irgasan, novobiocin, bile salts, and crystal violet) to prevent the growth of most bacteria. The agar also contains a pH indicator that turns red or pink when mannitol is fermented; with Yersinia having a characteristic ‘bull’s eye’ colonies with red centers and clear edges. CIN is incubated at room temperature for 48 hours. Finally, Campy CVA agar is a selective media for Campylobacter containing antimicrobial agents cefoperazone, vancomycin, and amphotericin B (CVA) which inhibit normal fecal flora. This media is incubated at 42°C under microaerophilic conditions, which support the growth of Campylobacter jejuni and C. coli.

Our patient’s culture grew gray, non-hemolytic colonies on Campy CVA agar (Figure 2). The organism was identified as Campylobacter jejuni by MALDI-TOF MS (matrix-assisted laser desorption/ionization, time of flight mass spectrometry).

camp2
Figure 2. Bacterial colonies growing on Campy CVA agar

Campylobacter are gram-negative, microaerophilic, curved or spiral rods in the family Campylobacteriaceae. They are widely distributed in animals and infection is most often transmitted by contaminated foods, particularly undercooked chicken. The species most commonly associated with human infections are C. jejuni and C. coli, with C. jejuni accounting for the large majority. Infection with C. jejuni has been linked with subsequent development of Guillain-Barre syndrome two to three weeks following the initial illness. Our patient improved following two days of IV fluids and antibiotics with no subsequent follow up after discharge.

 

References:
Manual of Clinical Microbiology, 11th edition

 

-Said Albahra, MD,  1st year Anatomic and Clinical Pathology resident at the University of Texas Southwestern Medical Center.

-Erin McElvania TeKippe, Ph.D., D(ABMM), is the Director of Clinical Microbiology at Children’s Medical Center in Dallas Texas and an Assistant Professor of Pathology and Pediatrics at University of Texas Southwestern Medical Center.

Microbiology Case Study: 58 Year Old Man with Fatigue and Chills

Case History:

Two weeks after returning from a camping vacation in Cape Cod, a 58 year old man presented to the emergency room with six days of fatigue, fever, chills, arthralgia, myalgia, mild right upper quadrant pain, and a frontal headache. Clinical workup revealed worsening leukopenia, thrombocytopenia, and elevated transaminases when compared to preliminary testing done by the patient’s primary care provider at the onset of his symptoms. His preliminary workup was also negative for Lyme antibody, EBV and CMV IgM, and viral hepatitis markers. At no point did the patient notice a skin rash or a tick anywhere on his person.

Differential Diagnosis:

  • Lyme Disease
  • Anaplasmosis
  • Ehrlichiosis
  • Babesiosis
  • Rocky Mountain Spotted Fever
  • Viral Meningitis
  • Bacterial Meningitis
  • Leptospirosis
Blood smear showing granulocyte with intracytoplasmic morulae.
Blood smear showing granulocyte with intracytoplasmic morulae.
Blood smear showing granulocyte with intracytoplasmic morulae.
Blood smear showing granulocyte with intracytoplasmic morulae.

Laboratory Identification:

Anaplasma phagocytophilium was initially identified by PCR. Retrospectively, the blood smears originally examined for Babesia by both hematology and parasitology were reviewed. Both slides showed multiple granulocytes with intracytoplasmic morulae.

 

Discussion

Anaplasma phagocytophilium is the bacterium responsible for the tick-borne disease known as human granulocytic anaplasmosis. Anaplasma is transmitted to humans primarily through the bite of an infected Ixodes scapularis, the same species of tick which transmits Borrelia burgdorferi (Lyme disease) and Babesia spp. (human babesiosis). Anaplasmosis, Lyme disease, and babesiosis therefore share roughly the same geographical distribution in the United States with northeastern and upper midwestern states reporting the most cases.

Anaplasmosis most commonly presents about 1-2 weeks after a tick bite with the sudden onset of a variety of non-specific symptoms including fever, chills, headache, malaise, myalgia, nausea, and abdominal pain. Anaplasmosis, unlike other tick-borne diseases, rarely causes a rash. Routine blood tests may show thrombocytopenia, leukopenia, or elevated liver enzymes in some patients. Severe clinical presentations, more common in immunosuppressed patients, may include difficulty breathing, hemorrhage, renal failure or neurological problems. Anaplasmosis is estimated to be fatal in less than 1% of cases.

A routine blood smear is the quickest method for establishing an early presumptive diagnosis. Microscopic examination of the smear may reveal microcolonies of Anaplasma known as morulae within the cytoplasm of infected granulocytes. Ehrlichia, in contrast, will preferentially target and form morulae within monocytes. Because not all patients with anaplasmosis have visible morulae, this test is diagnostically insensitive and should be followed by further testing.

Confirmatory serologic testing for anaplasmosis includes an indirect immunofluorescence assay using an Anaplasma phagocytophilum antigen. For the highest sensitivity, this test should be performed on paired serum samples collected at least 2 weeks apart with the first sample taken as early in the disease as possible. A positive test will demonstrate a four-fold rise in antibody titers. Although it is a very sensitive detection method when run with paired samples, the lengthy testing time is less than ideal for patients requiring hospitalization for their disease.

A PCR assay on a sample of whole blood, although only available at a few reference laboratories, is the most efficient and accurate way to detect Anaplasma during the acute phase of the illness. The sample used for PCR testing should be taken before the initiation of antibiotic therapy as it causes the sensitivity of this test to rapidly decline.

Doxycycline is the first line treatment for adults and children of all ages with anaplasmosis as recommended by both the CDC and the AAP Committee on Infectious Diseases. Patients should be treated for at least 3 days after the fever subsides. Standard duration of treatment is 7 to 14 days. Therapy should be initiated immediately when there is a high clinical suspicion of anaplasmosis. A physician should never wait for the results of confirmatory testing to begin treatment. Most patients see improvement within 24-48 hours of treatment and non-response to doxycycline may indicate a different disease process.

Anaplasmosis, like many other tick-borne diseases, is a nationally reportable disease. All cases should be reported to local and state health departments as well as the CDC.

-Elaine Amoresano, MD, is a 1st year anatomic and clinical pathology resident at the University of Vermont Medical Center.

Wojewoda-small

-Christi Wojewoda, MD, is the Director of Clinical Microbiology at the University of Vermont Medical Center and an Assistant Professor at the University of Vermont.

Microbiology Case Study: 29 Year Old in Preterm Labor at 30 Weeks Gestation

Case History:
A 29 year old woman presents to the hospital with contractions at 30 weeks gestation. This is her first pregnancy and it was previously uncomplicated. She did not experience loss of fluid or vaginal bleeding and did not have a history of recent illness or fever. A swab for group B Streptococcus (GBS) was collected and the patient was started on prophylactic penicillin. Clinical evaluation revealed evidence of acute infection with an elevated C-reactive protein and an increased white blood cell count with 97% neutrophils. Amniocentesis was performed and the amniotic fluid was sent to the laboratory for Gram Stain and culture.

Labor was allowed to progress and the infant was delivered vaginally. Cultures of cerebrospinal fluid and blood from the neonate were negative. The placenta was sent for histologic evaluation.

Gram stain shows Gram negative bacilli.
Gram stain shows Gram negative bacilli.
Tiny gray colonies on blood agar with a bleach-like odor.
Tiny gray colonies on blood agar with a bleach-like odor.
Small, pale yellow colonies on chocolate agar.
Small, pale yellow colonies on chocolate agar.

Laboratory Identification:
The laboratory workup revealed a gram negative bacillus with rounded ends that grew small grey to pale yellow colonies on blood and chocolate agars. The colonies had three regions; a raised central region, a refractile flat region, and an outer rougher spreading region. The colonies had a distinct bleach-like smell. There was no growth on MacConkey agar. The organisms were oxidase positive, catalase and indole negative. Mass spectrometry was utilized to identify the organism as Eikenella corrodens.

Discussion:
Eikenella corrodens is a component of normal mouth and upper respiratory tract flora. It is most notable for causing head and neck infections, periodontal disease, and as a significant player in “fight bite” infections. “Fight bite” results when a clenched fist hits another person’s mouth and the teeth cause lacerations to the hitter’s hand, which can subsequently lead to infection. Eikenella is implicated approximately 25% of the time in these types of infections. Only on very rare occasion is Eikenella known to cause gynecologic infections. Endometritis or cervicitis may infrequently be caused by colonization of an intrauterine contraceptive device (IUD) by Eikenella. And rarely, Eikenella is implicated as the isolated bacteria in cases of acute chorioamnionitis.

In the medical literature there are currently only 8 reported cases of chorioamnionitis caused by a pure Eikenella infection. As in our case, each of the women in the case reports had clinically silent infections and only presented with preterm labor. Most of the women were found to have elevated white blood cell counts in the absence of fever or alterations in other vital signs. In each case, the fetal membranes were intact. Two of the cases resulted in fatal infection of the neonates. Of note, three of the women were mentioned to be the recipients of oral intercourse throughout their pregnancies.

One of the reported cases involved a woman whose partner had a tongue piercing and it was noted that they engaged in daily oral sex during the pregnancy.  The authors speculated that the tongue piercing played a role in the development of chorioamnionitis by either ascending vaginal infection or hematogenous spread caused by trauma from the tongue ring.

It is not known if a similar history was present in this case. The patient was treated with ampicillin and gentamycin and discharged following delivery. She is currently doing well. The infant has had no signs of infection, but at the time of this writing he is being treated in the neonatal intensive care unit for sequelae of prematurity.

References:
Garnier F, Masson G, Bedu A, et al. Maternofetal infections due to Eikenella corrodens. J Med Microbiol 2009; 58, 273-275.

Jadhav A, Belfort M, Dildy G. Eikenella corrodens chorioamnionitis: modes of infection? Am J Obstet Gynecol 2009; 200, e4-5.

-Britni Bryant, MD is a 2nd year anatomic and clinical pathology resident at the University of Vermont Medical Center.

Wojewoda-small

-Christi Wojewoda, MD, is the Director of Clinical Microbiology at the University of Vermont Medical Center and an Assistant Professor at the University of Vermont.