Microbiology Case Study: 64 Year Old Male with Pleuritic Chest Pain and Fevers

Case History

The patient is a 64 year old male with a history of diabetes mellitus and hypertension who presented as a transfer from an outside hospital with a 2 week history of chest pain and pressure, as well as recurrent fevers, rigors, and soaking sweats, and an echocardiogram concerning for a pericardial effusion. He was also found to have markedly elevated CRP, and mildly elevated troponins, was diagnosed with pericarditis, and was started on colchicine. He continued to have fevers, and developed diarrhea and was transferred for elevation of care. C. difficile PCR was negative, and since the onset of diarrhea coincided with the initiation of colchicine, that was determined to be the cause. Blood cultures on arrival grew a Gram positive rod and a transesophageal echocardiogram was done which again showed pericardial thickening with small effusion, and fluid with fibrinous appearance. There was no evidence of valvular vegetation. At this point the patient was started on IV meropenam as he is allergic to penicillin’s and sulfa drugs. The pericarditis seemed to improve with colchicine so a non-infectious process was favored and a repeat ANA was recommended when he has recovered from his current infection.

Laboratory Identification

listermono1
Image 1. Gram Stain of blood culture showing gram positive palisading rods.
listermono2
Image 2. Gray-white colonies with soft β-hemolysis on blood agar.

Blood cultures grew grey-white colonies that are gram positive, catalase positive rods with soft beta-hemolysis on the blood agar plate, and tumbling motility under light microscopy. CAMP testing would be positive with Staphylococcus aureus. This was identified as Listeria monocytogenes by the MALDI. 

Discussion

Listeria monocytogenes is a gram positive rod that can be found in the soil, water, sewage, vegetation, and as part of the fecal flora of animals. It is facultative intracellular pathogen that is able to invade and survive in human cells including macrophages (1). They possess a surface protein called internalin that interacts with E-cadherin on human cells resulting in endocytosis (1). Once within the cell the bacteria can produce listeriolysin O and other phospholipases which allow it to escape from the phagosome before it fuses with the lysosome, which prevents intracellular killing of the bacteria (2). L. monocytogenes is a common contaminant of food products as it can form biofilms on the food surfaces. Listeria also has the ability to grow a 4°C so it can continue to grow on refrigerated foods (1). Foods such as raw milk, raw vegetables, fish, poultry, and fresh and processed meats are the highest risk for contamination.

Ingestion during pregnancy can result in a flu like illness, occasionally with vaginal discharge, diarrhea, and urinary tract symptoms (1). Infection during pregnancy is particularly dangerous as occult bacteremia with transplacental transmission may occur (2). Infection in utero may result in premature labor and birth of an infected or stillborn fetus. Prognosis is highly dependent on the gestational age at infection.

Non- pregnant adults can also become infected by Listeria. The most common results of ingestion of contaminated food in immunocompetent patients is a transient asymptomatic carrier state, and can be excreted in the feces. Less commonly, febrile gastroenteritis can occur. Immunocompromised patients or those with underlying malignancy tend to present with acute sepsis, meningitis, or meningoencephalitis.  Focal infections such as cutaneous infection, abscesses, arthritis, peritonitis, liver/splenic abscess, cholecystitis, artificial joint/graft infections, osteomyelitis, and myo- and endocarditis can be seen and typically occur in immunocompromised patients as a results of hematogenous spread.1 Treatments includes ampicillin with or without an aminoglycoside. Occasional resistance to tetracyclines has been reported.2

Regarding the patient’s Listeria bacteremia, the patient reported no exposures to the common carriers of Listeria. It is possible that is was translocated from his gut during his diarrhea illness or could have been the cause of his diarrhea, although blood cultures at the outside hospital were negative.

References

  1. Winn, Washington C., et al. Color Atlas and Textbook of Diagnostic Microbiology. Lippincott Williams & Wilkins, 2006.
  2. Tille, Patricia M. Bailey & Scotts Diagnostic Microbiology. 13th ed., Elsevier, 2014.

 

-Casey Rankins, DO, 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 Associate Professor at the University of Vermont.

Chemisty Case Study: Heat-Insoluble Cryoglobulin

Case History

A 50 year old female was admitted for acute renal failure on CKD stage IV, present with gross hematuria, anemia (due to blood loss) and hypertension. The patient has a significant history of unresolved cryoglobulinemic vasculitis initially diagnosed in 2016 and has been treated by several rounds of rituximab. Other medical histories include Sjogren’s syndrome, MGUS with monoclonal IgM Kappa, coagulopathy (protein S deficiency, on anticoagulant), hyperviscosity, myalgia, deep vein thrombosis, leg edema with superficial ulcer, pulmonary embolus and membranoproliferative glomerulonephritis (MPGN). Kidney biopsy revealed intraglomerular hyaline thrombi consistent with cryoglobulinemic glomerulopathy, interstitial fibrosis tubular atrophy, arterial sclerosis, suggestive thrombotic microangiopathy. Immunohistochemistry was positive for C3, IgM, Kappa, Lambda and CD68. Bone marrow biopsy shown dyserythropoesis without malignancy. Blood testing shown negative hepatitis panel and undetectable C4.

We observed unusual cryoprecipitate test results from this patient: gelatinous appearance precipitate which accounts for more than 40% of volume was observed in both plasma and serum and cannot be cleared at 37C° after several hours of incubation. Further testing shown incubation at 56°C for 30min cleared up the serum but not the plasma. After checking the test history, we found that there was a similar situation for the patient’s cryoprecipitate test a few months back earlier in 2018, and was reported negative for cryoglobulins due to the heat-insoluble nature of the precipitate. Patient was transfused for anemia. No plasmapheresis was done. Due to the patient’s incomplete response to rituximab, Cytoxan was also added to help improve the symptoms.

Cryoprecipitate

  • Definition: Cryoprecipitates (or cryoproteins) are blood proteins that form precipitates or gels at temperatures lower than 37°C and typically re-dissolve after warming up to 37°C. There are two types:
  • Cryoglobulin (CG): precipitate from both serum and plasma; either immunoglobulins or a mixture of immunoglobulins and complement components
  • Cryofibrinogen (CF): precipitate from plasma only; typically composed of a mixture of fibrinogen, fibrin, fibronectin, and fibrin split products
  • Lab Testing done in our hospital:
    1. Blood are collected in two pre-warmed tubes (one serum, one EDTA plasma) and kept in warm water (37°C) until the serum tube clots.
    2. The plasma and serum are extracted at room temperature, and then stored in refrigerator for 72 hours.
  • If cryoprotein is present, a precipitate or gel will be seen. An aliquot of the serum is rewarmed at 37°C to verify the cryo-nature.
  1. The precipitate as a percentage of the original serum volume is measured in an ESR tube to determine the cryocrit.
  2. Immunofixation is ordered per pathologist to identify the immunoglobulin compositions of the cryoglobulin.

Cryoglobulinemia

  • Classification

Strictly speaking, cryoglobulinemia refers to the presence of cryoglobulin (CG) in a patient’s serum, which could be either asymptomatic or present with apparent clinic syndromes (i.e. cryoglobulinemic vasculitis). Cryoglobulinemia can be classified into three types (see table below [1]), with mixed cryoglobulinemia (type II and type III) representing 80% of the cases.

cryo1

  • Clinical Manifestations

Type I cryoglobulinemia is frequently asymptomatic, while mixed cryoglobulinemia manifests clinically by a classical triad of purpura, weakness and arthralgias, as well as some other conditions including MPGN, chronic hepatitis, peripheral neuropathy, lymphoma, Raynaud’s, Sjogren’s syndrome, etc.

The presence of heat-insoluble cryoglobulins is rare, and its pathogenesis is poorly understood. On the other side, it may indicate sever clinical consequence as seen in our case and some others as mentioned above.

Reference

  1. Mixed Cryoglobulinemia, Ferri, C; Orphanet Journal of Rare Diseases 2008, 3:25

 Further reading

  1. Essential type II cryoglobulinemia with cryoglobulin-occlusive MPGN and MGUS (Clin Chim Acta. 2009 Aug;406(1-2):170-3):79 y.o. female admitted due to edema and renal failure, cryoglobulin re-dissolved at 56°C, composed of monoclonal IgG-Kappa and polyclonal IgM.
  1. HCV associated thrombotic microangiopathy and cryoglobulin-occlusive MPGN (Am J Med Sci. 2013 Oct;346(4):345-8):57 y.o. female, cryoglobulin re-dissolved at 47°C, composed of monoclonal IgM-Kappa and polyclonal IgG. Symptoms only partially resolved upon treatment of plasmapheresis, corticosteroids and antiviral therapy of peginterferon plus ribavirin.
  1. Essential type I cryoglobulinemia with massive cryoglobulin-occlusive glomerulonephritis (Am J Kidney Dis. 1995 Oct;26(4):654-7):54 y.o. male progressed to ESRD prior to the detection of cryoglobulin. Cryoglobulin with white gelatinous appearance re-dissolved at 54°C, composed of monoclonal IgG-Kappa.
  1. Primary Sjogren’s syndrome with type II cryoglobulinemia and mesangiocapillary glomerulonephritis (Nephrol Dial Transplant. 2000 Jun;15(6):917-8):82 y.o. patient with IgM-MGUS, negative BM, deposition of IgG, IgM and C3 on kidney biopsy, decreased complement levels, negative HCVAb, HBsAb, HBsAg. cryoglobulin re-dissolved at 47°C, composed of monoclonal IgM-Kappa and polyclonal IgG-Kappa.

 

Huang

-Rongrong Huang, PhD is a first year clinical chemistry fellow at Houston Methodist Hospital. Her interests include general clinical chemistry, genetic biochemistry and applications of mass spectrometry in clinical laboratories.

Xin-small

-Xin Yi, PhD, DABCC, FACB, is a board-certified clinical chemist, currently serving as the Co-director of Clinical Chemistry at Houston Methodist Hospital in Houston, TX and an Assistant Professor of Clinical Pathology and Laboratory Medicine at Weill Cornell Medical College.

Microbiology Case study: 48 Year Old Male with Multiple Injuries Following a Motorcycle Accident

Case History

The patient is a 48 year old male who presented after a motorcycle crash where he slide sideways into a ditch. He did not lose consciousness. At presentation he complained of pain across the abdomen, right wrist and left shoulder. He also had shortness of breath and chest wall pain. He denied hitting his head and was helmeted. He underwent exploratory laparotomy with repair of traumatic diaphragmatic hernia and left chest tube placement with post-operative course complicated by significant leukocytosis and bandemia on post-operative day 5 which triggered CT re-imaging of the chest/abdomen/pelvis. This study demonstrated intraperitoneal free air that prompted repeat exploratory laparotomy with subtotal colectomy with the abdomen open and wound vac in place. On post-operative day 9 the patient had an increasing white count that prompted return to OR with bowel staple line demonstrating leak, which prompted a small bowel resection, and ileostomy formation. After leaving the OR, the patient experienced worsening septic shock. Aggressive antibiotic therapy and IV fluid resuscitation was continued. Blood cultures taken on post-operative day 9 grew a large Gram positive rod. Growth of this organism was seen both aerobic and anaerobically.

Laboratory Identification

closter1
Image 1. Gram stain of the anaerobic blood culture bottle showing gram positive/variable rods.

 

closter2.jpg
Image 2. Aerobic blood agar plate showing small clear colonies.

Blood cultures showed box shaped gram positive/ variable rods that were growing on blood agar plates both aerobe and anaerobically. It was motile, indole and catalase negative, and esculin positive, and was identified by the MALDI to be Clostridium tertium.

Discussion

Clostridium tertium is an aerotolerant gram positive rod that is widely distributed in the soil and can also be found the GI tract of animals and humans (1). C. tertium is non-toxin producing and produces terminal spores in anaerobic conditions (2). Infection with C. tertium is uncommon though it has been increasing in frequency as a cause of bacteremia, especially in patients with neutropenia, the immunocompromised, those with hematologic malignancy, those with inflammatory bowel disease, and in people with abdominal trauma or who have undergone abdominal surgery. Less commonly, C. tertium can be isolated in spontaneous bacterial peritonitis, enterocolitis, meningitis, septic arthritis, necrotizing fasciitis, post-traumatic brain abscess, and complicated pneumonia in mono- or polymicrobial infections (1). Additionally there has been a link between C. tertium infection and attempted suicide with the herbicides containing Glyphosate, as it causes GI toxicity which alters the gut environment (2). As with Clostridium difficile, the use of broad-spectrum antibiotics such as third-generation cephalosporins might predispose to intestinal colonization with C. tertium (1).

Increases in the diagnosis of C. tertium may be related to better diagnostic equipment such as the MALDI as it can easily be confused with a facultative anaerobic Bacillus or Lactobacillus species due to its gram variable appearance and ability to grow in aerobic conditions. A distinguishing feature between Bacillus species and C. tertium is negatively of the catalase reaction as Bacillus should be positive. Lactobacillus can still be a challenge as they are also catalase negative.

The treatment of C. tertium infection is complicated due to resistance to various antibiotics, including various beta-lactam antibiotics (such as third- and fourth-generation cephalosporins), clindamycin, daptomycin, and cotrimoxazole. Older reports state resistance to metronidazole, but this has not been confirmed in more recent publications. Available data indicate sensitivity to vancomycin, carbapenems, and quinolones (1)(3).

References

  1. Salvador F, Porte L, Durán, L, Marcotti A, Pérez J, Thompson L, Noriega LM, Lois V, Weitzel T. Breakthrough bacteremia due to Clostridium tertium in a patient with neutropenic fever, and identification by MALDI-TOF mass spectrometry. International Journal of Infection Disease. 2013;17:11 (1062-1063). https://doi.org/10.1016/j.ijid.2013.03.005
  2. You M-J, Shin G-W, Lee C-S. Clostridium tertium Bacteremia in a Patient with Glyphosate Ingestion. The American Journal of Case Reports. 2015;16:4-7. doi:10.12659/AJCR.891287.
  3. Miller D, Brazer S, Murdoch D, Reller LB, Corey, GR. Significance of Clostridium tertium Bacteremia in Neutropenic and Nonneutropenic Patients: Review of 32 Cases. Clinical Infectious Diseases. 2001; 32:975–8

 

-Casey Rankins, DO, 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 Associate Professor at the University of Vermont.

Microbiology Case Study: A 3 Year Old Boy with Gastrointestinal Illness and Severe Dehydration

Case History

A 3 year old Caucasian male presented to the hospital due to a gastrointestinal illness and severe dehydration. Per parents, the patient started having diarrhea 4 days prior to admission. Initially, the diarrhea was watery, yellow, and foul-smelling but then became bloody and intermixed with clots. Diarrhea episodes were occurring every 20 minutes and associated with severe abdominal cramping. Additional symptoms included vomiting and malaise, but no fever was noted. There was no history of travel and no one else in the family or at daycare had similar symptoms. On physical examination, there was diffuse abdominal tenderness, signs of dehydration and altered mental status. Vitals showed an elevated blood pressure (144/97) and tachycardia (140 beats/minute). Initial lab work revealed a marked leukocytosis with left shift (78.9 TH/cm2, 62% neutrophils, 11% bands), normal hemoglobin & hematocrit, and a slight thrombocytopenia (156,000 TH/cm2). Notably, the renal panel showed kidney injury (BUN 79 mg/dL and creatinine 3.29 mg/dL) and a significantly elevated LDH (9,408 U/L).  Blood and stool specimens were collected for culture and the patient was started on fluids for rehydration therapy.

Laboratory Identification

O157-1.png
Image 1.The stool culture identified a lactose positive (pink colonies on MacConkey agar, left), sorbitol negative (clear colonies on MacConkey-Sorbitol, right) gram negative rod.
O157-2
Image 2. The Shiga toxin lateral flow assay was positive for Shiga toxin 2.

The isolate was identified as Escherichia coli O157 by Vitek and latex agglutination was positive. Additionally, the patient had a GI PCR panel performed which was also positive for E. coli O157 and Shiga-like toxin-producing E. coli stx1/stx2.  The specimen was sent to the department of health which also confirmed the identification of E. coli O157:H7 by molecular methods. All blood cultures remained negative. Based on the clinical presentation and culture results, the child was diagnosed with hemolytic uremic syndrome (HUS).

Discussion

Escherichia coli is a gram negative rod that a member of the Enterobacteriaceae family. General features of the genus include fermentation of glucose, a negative oxidase reaction, and most strains having the ability to ferment lactose. E. coli is a normal component of gastrointestinal flora, but pathogenic strains can cause illness due to ingestion of contaminated food or water, contact with animals, or person to person spread. In the case of E. coli O157:H7, the infectious dose can be as small as 10-100 CFU.

The clinical syndromes caused by E. coli O157:H7 are commonly referred to as Shiga toxin-producing E. coli (STEC) or enterohemorrhagic E. coli (EHEC).  Most commonly, E. coli O157:H7 is due to ingestion of undercooked ground beef. Presentations can range from mild non-bloody diarrhea to severe hemorrhagic colitis with hemolytic uremic syndrome (HUS). HUS is characterized by a hemolytic anemia, decreased platelets and organ damage, including renal failure and altered mental status. While only 4% of those infected with E. coli O157:H7 develop HUS, at least 80% of HUS cases in North America are due to E. coli O157:H7.

When a stool culture in received in the laboratory, a selective and differential agar to identify E. coli O157:H7 is always used. This is due to the fact that the majority E. coli O157:H7 do not ferment sorbitol. If a sorbitol negative E. coli is identified, latex agglutination is used to confirm the isolate is O157. In addition, lateral flow assays for the detection of the Shiga toxin 1 & 2 proteins are also performed as part of the routine stool culture to detect E. coli isolates that ferment sorbitol or are serotypes other than O157. Molecular testing to detect Shiga toxins provides a sensitive method of detection with an improved turnaround time. Presumptive isolates should be sent to the state department of health for confirmation and monitoring of potential outbreak situations.

Treatment for E. coli O157:H7 is generally supportive as it has been reported that certain antibiotics may stimulate further toxin production, thereby increasing the risk of HUS and as such, no routine susceptibility testing is recommended for STEC strains. Patients may need dialysis in the event of renal failure.

In the case of our patient, he had a prolonged disease course that necessitated dialysis and was complicated by a bowel perforation and pancreatitis. While his condition improved, he still requires dialysis three times a week.

 

AlAl

-Aljunaid Alhussain, MD, is a first 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. She is certified by the American Board of Pathology in Anatomic and Clinical Pathology as well as Medical Microbiology. She is the Director of Clinical Pathology as well as the Microbiology and Serology Laboratories.  Her interests include infectious disease histology, process and quality improvement, and resident education.

Microbiology Case Study: a 77 Year Old Woman with a Splenic Abscess

Case History

The patient is a 77 year old woman with a past medical history significant for hypertension, hyperlipidemia, diverticulitis, and advanced vascular disease with mesenteric ischemia and post-prandial pain who presented to an outside hospital with severe diffuse abdominal pain. Of note she was scheduled to undergo endovascular repair of a known occluded celiac artery. Imaging at the outside hospital showed intraperitoneal free air and a fluid collection by the tail of the pancreas. The inferior mesenteric artery was patent but the celiac and superior mesenteric artery were occluded. The lesion at the tail of the pancreas was previously known to the patient, work up showed it was benign. The patient was transferred to our facility and was taken urgently to the OR for exploratory laparotomy for diffuse peritonitis. During surgery the patient was found to have an infarcted spleen with a splenic abscess; no ischemic bowel was seen. A surgical mesh was in place from a previous hernia surgery and was removed. A drain was placed in the abscess and the abdomen was closed. The patient was placed on Zosyn intraoperatively and remained on Zosyn following transfer to the ICU. On post-operative day 6, Zosyn was switched to Ertepenam due to IV and dosing problems.

Laboratory Identification

closperf1
Image 1. Box shaped gram positive rod identified on Gram stain of splenic abscess culture (100x oil immersion).
closperf2
Image 2. Mixed culture anaerobic growth. Pathogen of interest is clear and spreading causing a double zone of beta-hemolysis (Schaedler blood agar plate).

An aspirate from the abscess was sent to the lab for aerobic and anaerobic culture. Cultures from the abscess showed mixed gram positive and gram negative aerobic and anaerobic organisms. Of note, there was a gram positive rod which showed a double zone of beta hemolysis on the Schaedler blood plate, which grew only in anaerobic conditions. The colonies are clear/gray. The organism is catalase negative and indole positive, and was identified by the MALDI as Clostridium perfringens.

Discussion

C. perfringens is an anaerobic gram positive spore forming rod. This organism is known to cause myonecrosis, gas gangrene, gangrenous cholecystitis, bacteremia, food poisoning, and is a worldwide cause of necrotizing enterocolitis (1). The main virulence factor is the alpha toxin, which is a hemolytic toxin with both phospholipase C and sphingomyelinase activities and is essential in disease. The toxin can rapidly breakdown phospholipid membranes, which is particularly dangerous because it can cause massive intravascular hemolysis in bacteremic patients (1, 2). It is important to recognize the signs of infection early as bacteremia can have a mortality rate of up to 75% (1). Splenic abscess with C. perfringens is rare with only a few case reports in the literature. Typically, splenic abscess are caused by aerobes such as Escherichia coli, Staphylococcus ssp., Streptococcus ssp., and Salmonella ssp. Infection with anaerobes account for only 10% of splenic infections (3). Those with clostridial infections typically had a predisposing condition such as colitis, diabetes, trauma, or malignancy (3).

 

References

  1. Hashiba M, Tomino A, Takenaka N, et al. Clostridium Perfringens Infection in a Febrile Patient with Severe Hemolytic Anemia. The American Journal of Case Reports. 2016;17:219-223. doi:10.12659/AJCR.895721.
  2. Awad MM, Bryant AE, Stevens DL, Rood JI.  Virulence studies on chromosomal alpha-toxin and theta-toxin mutants constructed by allelic exchange provide genetic evidence for the essential role of alpha-toxin in Clostridium perfringens-mediated gas gangrene. Molecular Microbiology. 1995;15(2):191.
  3. Chalasani, Rajendra MD; Siripurapu, Shantipriya MD; Hasan, Saqib MD. Splenic Abscess due to Clostridium perfringens: A Rare Entity. Infectious Diseases in Clinical Practice. 2007;15(2);137-138.

 

-Casey Rankins, DO, 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 Associate Professor at the University of Vermont.

Microbiology Case Study: A 14 Year Old Immunocompromised Male with Pneumonia

Case History

A 14 year old male with a history of selective IgG deficiency, asthma, and GE reflux s/p Nissen Fundoplication, presented to the pediatric pulmonary clinic with 2 weeks of cold like symptoms that progressed to a wet sounding cough productive of sputum and chest pain. 5 days prior he had seen his primary care physician who diagnosed him with pneumonia and started him on amoxicillin and 5 days of prednisone (60mg daily). He is using his albuterol nebulizer every 3 hours, and feels as though his asthma may be contributing to his symptoms but is not the main cause as he has not had a wet cough and chest heaviness and pain with previous asthma attacks. He has had low grade fevers for the past several days but denies chills, sweats, or hemoptysis.  Of note his immune deficiency is treated with IVIG and long term Bactrim which was recently stopped. Pediatric pulmonology elected not to restart the Bactrim but changed his antibiotic to Augmentin. The patient continued to have chest pain and coughing, so the decision was made to proceed with bronchoscopy

Laboratory Identification

zygo-1
Image 1. Scotch tape prep showing broad hyphae with rare septation and round sporangia.
zygo-2
Image 2. Colonies with growth at 30° and 37° C showing “fluffy” growth with darkening in the center of the colony.

Cultures from the BAL revealed a rapidly growing fungi with broad hyphae (5 to 15 micron diameter) that are irregularly branched, and have rare septations. These features, paired with the morphology of the sporangia are diagnostic for a Zycomycete; further identification was attempted however, rhizoids characteristic of Rhizopus, and branching characteristic of Mucor were not identified in this culture.

Discussion

Zygomycetes (Mucormycetes) are widely distributed in the environment in soil and vegetation and infection is through inhalation of spores. Typically, the spores are transported by the muco-cilliary escalader to the pharynx, are swallowed, and then are broken down by the GI tract. In immunocompromised patients, the spores can settle in the nasal turbinates and alveoli causing disease (1). The most common sites of infection are rhino-orbital-cerebral and pulmonary and typically occur in immunocompromised hosts and diabetics (2). The Zygomycetes are also known to invade blood vessels making tissue infarction and necrosis one of the hallmarks of the disease (3). These fungi grow rapidly and are often referred to as “lid lifters” when cultured. Because of this rapid growth, infection with Zygomycetes typically progress quickly and cause periorbital edema, proptosis, and blindness. Facial numbness can occur if there is infarction of sensory branches of the fifth cranial nerve. Infection can spread from the ethmoid sinus to the frontal lobe and result in obtundation. If infection spreads from the sphenoid sinuses to the adjacent cavernous sinus, it can result in cranial nerve palsies, thrombosis of the sinus, and involvement of the carotid artery (4). When the spores are inhaled into the lung, pneumonia with infarction and necrosis results. The infection can spread to contiguous structures, such as the mediastinum and heart, or disseminate hematogenously to other organs such as the GI tract, kidney, and brain (5). Infections are treated with a combination of antifungal drugs such as Amphotericin B, and aggressive surgical debridement. In some situations removal of the palate, nasal cartilage, and orbit are necessary for cure. In patients with pneumonia, often lobectomy is needed for cure (5).

The genera most commonly found in human infections are Rhizopus, Mucor, and Rhizomucor. Rhizopus organisms have an enzyme called ketone reductase, which allows them to thrive in high glucose, acidic conditions, such as in individuals with diabetic ketoacidosis. Rhizopus will have root like rhizoids and are typically located near the sporangiophores. The post-mature sporangiophores can undergo “umbrella like” collapse which is characteristic of Rhizopus. Mucor is more likely to have branching and is often identified when all other species are ruled out; they do not produce a rhizoid.
References

  1. Ferguson BJ. Mucormycosis of the nose and paranasal sinuses. Otolaryngology Clinics of North America. 2000;33(2):349.
  2. Kauffman CA, Malani AN. Zygomycosis: an emerging fungal infection with new options for management. Current Infectious Disease Reports. 2007;9(6):435.
  3. Greenberg RN, Scott LJ, Vaughn HH, Ribes JA. Zygomycosis (mucormycosis): emerging clinical importance and new treatments. Current Opinions in Infectious Diseases. 2004;17(6):517.
  4. Yohai RA, Bullock JD, Aziz AA, Markert RJ. Survival factors in rhino-orbital-cerebral mucormycosis. Survey of Ophthalmology. 1994;39(1):3.
  5. Tedder M, Spratt JA, Anstadt MP, Hegde SS, Tedder SD, Lowe JE. Pulmonary mucormycosis: results of medical and surgical therapy. Annals of Thoracic Surgery. 1994;57(4):1044.

 

-Casey Rankins, DO, 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 Associate Professor at the University of Vermont.

Microbiology Case Study: A 10 Month Old Female with Fever and Shoulder Pain

Case History

A 10 month old African American female presented to the emergency department with fever (101.9°F) and a two day history of left shoulder pain. Her mother reported guarding and refusal to move the left arm. There was no history of trauma and no other relevant past medical history. On examination, there was tenderness with gentle manipulation of left shoulder but no erythema or swelling were noted. She had full range of motion of elbow, wrist and finger joints with adequate sensation and pulses. Lab work showed a normal white blood cell count and increased ESR (52mm/hr, normal range: 0-20 mm/hr) and CRP (1.5 mg/dL, normal range: <1.00 mg/dL), suggestive of an infectious or inflammatory process. X-ray of the shoulder showed no bony abnormalities. Orthopedic surgery ordered an MRI which revealed a joint effusion concerning for septic arthritis. She underwent an aspiration with irrigation of the glenohumeral joint with drain placement and was subsequently started on clindamycin. The fluid was sent to the microbiology laboratory for Gram stain and bacterial culture. Multiple blood cultures were also collected.

Laboratory Identification

kingking1
Image 1. Two gray colonies grew in the first quadrant of the chocolate agar after 48 hours of incubation at 35°C in 5% CO2.
kingking2.png
Image 2. A sub from the above plate grew as small, grayish white colonies on blood and chocolate agars after 24 hours incubation at 35°C in 5% CO2. There was no growth on the MacConkey agar plate.
kingking3
 Image 3. Gram stain prepared from the chocolate agar plate showed gram negative bacilli in pairs (100x oil immersion).

The initial direct Gram stain from the fluid showed rare white blood cells and no organisms were identified. Two colonies of the organism grew on chocolate agar as small, grayish colonies after 48 hours incubation (Image 1). Upon subculture, the organism failed to grow on MacConkey agar (Image 2). Gram stain identified the isolate as gram negative bacilli, predominantly arranged in pairs (Image 3). The isolate was positive for oxidase and negative for catalase. MALDI-TOF MS identified the isolate as Kingella kingae. All blood cultures were negative.

 Discussion

Kingella kingae is a short, gram-negative bacilli that occur in pairs or short chains and require increased CO2 for optimum growth. K. kingae is the most common species responsible for human infections and is characterized as a fastidious gram negative rod of the HACEK group. K. kingae is a component of the normal flora in the oral cavity, throat, and upper respiratory tract of children and adults.

Bone and joint infections are the most common clinical manifestations of K. kingae infection in children and can present as bacteremia, septic arthritis, osteomyelitis and discitis. Children usually show symptoms including fever, swollen joints and decreased mobility with a recent preceding history of an upper respiratory tract infections or stomatitis with K. kingae gaining access to the bloodstream through damaged mucosa. In adults, those with poor dental hygiene, immunosuppression, or recent chemotherapy with mucositis are at risk for subacute bacterial endocarditis.

In the microbiology laboratory, K. kingae are facultative anaerobic gram negative bacilli that grow well on blood and chocolate agar plates after 48 hours. There is a small but distinct zone of beta-hemolysis on blood agar.  Unlike enteric organisms, K. kingae does not grow on MacConkey agar. Biochemical tests for K. kingae show a negative catalase reaction, positive oxidase positive reaction and they are non-motile. K. kingae is negative for indole and urease reactions. Automated identification instruments and MALDI-TOF mass spectrometry are able to identify K. kingae.

Beta-lactamase testing should be performed on K. kingae isolates as production among members of the HACEK group is well known. If the isolate is beta-lactamase positive, this predicts resistance to ampicillin, penicillin and amoxicillin. In general, K. kingae is susceptible to 3rd generation cephalosporins (and combinations with beta-lactam inhibitors), macrolides, fluoroquinolones and trimethoprim-sulfamethoxazole.

In the case of our patient, pediatric infectious disease was consulted and her antibiotic therapy was changed to IV cefazolin. She was discharged home with PO cephalexin for 3 weeks. On return to clinic, she was healing well with no complications.

 

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-Anu Abraham, MD, is a first 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. She is certified by the American Board of Pathology in Anatomic and Clinical Pathology as well as Medical Microbiology. She is the Director of Clinical Pathology as well as the Microbiology and Serology Laboratories.  Her interests include infectious disease histology, process and quality improvement and resident education.