A Teenager with Migrating Leg Pains and Anemia

A 14-year-old girl with a history of partial atrioventricular septal defect with a cleft mitral valve, repaired at 6 months of age, is referred to our pediatric tertiary care hospital from a community hospital with migrating leg pains and fevers. Leg pains began a week ago in her left thigh migrating to her dorsal left foot. After hospitalization, she develops right calf pain and paresthesia to the right foot. The pain fluctuates with no clear triggers, and she complains of difficulty walking. In the peripheral hospital, she received a dose of intravenous (IV) cefazolin before transfer to our facility for presumed osteomyelitis.On review of her history, she complains of a 2-month history of progressive fatigue and pallor but no weight loss. She has had tactile fevers for a week before hospitalization. Aside from paresthesias, she does not report neurologic symptoms. She is not short of breath or coughing, has no gastrointestinal or urinary symptoms, and has no skin or mucosal lesions. Her underlying cardiac diagnosis was a partial atrioventricular septal defect with a primum atrial defect and cleft mitral valve. She underwent patch repair of the primum septal defect at 6 months of age and has been stable with persistent mitral valve regurgitation, followed regularly by cardiology. An echocardiogram 6 weeks before presentation was reported to be stable with stable mitral valve regurgitation. Her travel history is unremarkable. She is not sexually active and denies alcohol or substance use. She has not undergone any recent surgical or invasive dental procedures.On examination she is very pale and tearful secondary to leg pain. She is afebrile with all vital signs stable and within normal range. She has a grade III/VI pansystolic murmur, with pulses palpable in all limbs and no appreciable hepatosplenomegaly. She is tender over her right calf and left navicular bone. There is no swelling or erythema to her limbs and no joint effusions. Her right calf feels cooler than the left. The remainder of the examination is unremarkable.Laboratory tests are as follows: hemoglobin of 7.9 g/dL (79 g/L), white blood cell count of 12,300/μL (12.3 × 109/L) with 87% neutrophils, platelet count of 125 × 103/μL (125 × 109/L), C-reactive protein of 223.6 mg/L (2,130 nmol/L), creatinine phosphokinase 3,825 U/L (64 μkat/L; normal range, 0.67–2.5 μkat/L), and D-dimer 9,254 μg/L fibrinogen-equivalent units (50.7 nmol/L FEU; normal < 3 nmol/L FEU). Her liver enzymes, creatinine, C3, and C4 are all within normal range, and rheumatoid factor is negative. Radiographs of the lower extremities show no fractures or signs of osteomyelitis. Blood cultures drawn at the community hospital grow coagulase-negative staphylococci (CoNS) after 12 hours of incubation in 4 out of 4 bottles.At the time of infectious diseases consultation, the differential diagnosis includes malignancy, venous thrombosis, infective endocarditis (IE), multifocal osteomyelitis, and rheumatologic etiology.During hospitalization, the patient continues to have intermittent severe right calf pain and is now noticing white patchy discoloration to the affected limb. Interval examination reveals an absent right dorsalis pedis pulse. An urgent Doppler ultrasound reveals occlusive thrombi to the right common femoral, right popliteal, and left superficial femoral arteries. An echocardiogram revealed a 1.8 × 1.6 cm vegetation on the anterior mitral valve leaflet resulting in severe mitral regurgitation. This finding, in the setting of a repaired cleft mitral valve, with residual mitral regurgitation and the clinical presentation of femoral arterial thrombus made IE the most likely diagnosis (Fig). Chest radiograph shows an enlarged left ventricle and interstitial opacification consistent with pulmonary edema. A computed tomography scan head rules out intracranial bleed; a subsequent computed tomography scan angiogram rules out major vessel cutoff, critical stenosis, or aneurysm. She is started on a heparin infusion and subsequently taken for emergency right-sided endarterectomy, thrombectomy, and fasciotomy due to the risk of muscular necrosis.Speciation of the positive blood culture is confirmed as Staphylococcus lugdunensis, which is found to be penicillin resistant but cloxacillin susceptible. Antibiotic therapy is switched to IV cloxacillin by continuous infusion, in order to maintain high serum levels, and IV rifampin is added due to persistently positive blood cultures.On day 6 of hospitalization, she returns to the operating room where a vegetation is removed from the inferior bridging leaflet of the mitral valve. Defects are also identified in both the superior bridging leaflet and the mitral valve cleft, which are repaired with bovine pericardial patches and sutures. Pathological assessment of the resected tissue identifies valvular material with focal necrosis and clusters of gram-positive cocci. Subsequently, her blood cultures sterilize, cloxacillin is switched to intermittent dosing, and rifampin is discontinued. Her fasciotomies are closed and she re-establishes good perfusion to both limbs. Repeat echocardiogram after 3 weeks shows mild-to-moderate mitral valve regurgitation, moderate mitral valve stenosis, and no evidence of vegetation. She completes 6 weeks of IV cloxacillin administered every 4 hours in a community hospital, followed by a course of oral antibiotics. Along with cardiology, she continues to be followed by hematology for anticoagulation management, orthopedics for dressing and splints, and physiotherapy for rehabilitation.IE remains a relatively uncommon condition in the pediatric population. It does, however, maintain a high risk of mortality with estimates ranging from 5% to 25%. (1)(2) Significant morbidity may occur in the form of congestive heart failure, periannular abscess, arrhythmia, metastatic infection, mycotic aneurysm, and sequelae of embolic events such as renal failure and stroke. (2)Congenital heart disease continues to be the single largest risk factor for IE in the pediatric population. Advancements in surgical practices have resulted in the risk shifting from children with uncorrected congenital heart disease to those in the prolonged postsurgical period, who are now surviving much longer. Children with anatomically normal hearts are experiencing increasing rates of IE, likely secondary to chronic indwelling central venous catheters, foreign implantable devices, and improved survival for premature infants and children with chronic diseases. (2)(3) Rheumatic heart disease was previously a substantial risk factor for IE, but has largely been eliminated in developed countries. (3) It still remains a large burden in underdeveloped areas. (4)The initial step in the pathophysiology of IE is damage to the vascular endothelium, which can result from turbulent blood flow in areas with abnormal cardiac structures. High velocity jets of blood denude the endothelium, which provides a surface for platelet and fibrin deposition. The subsequent thrombus that is formed serves as a nidus for infection with microbes traveling in the bloodstream. Transient bacteremia has been documented with normal daily activities such as brushing teeth, flossing, eating, and chewing gum. (5)The 3 groups of bacteria most commonly implicated in IE are the viridans group streptococci, Staphylococcus aureus, and Enterococcus species. (3) These gram-positive cocci express adhesins that are important in the initiation and propagation of infection at the site. CoNS are routinely isolated from blood cultures and their clinical significance can be difficult to interpret. Often, they are considered nonpathogenic skin commensals and attributed as contamination. S lugdunensis is a highly virulent CoNS organism that behaves much like S aureus. Its presence in culture should not be considered contamination and should be treated equivalently to S aureus. As with S aureus bacteremia, a high index of suspicion should be maintained for valvular vegetations and embolic complications.IE can present as an acute, rapidly progressing illness or a subacute illness that manifests over the course of several weeks. Symptoms of IE are nonspecific and include fever, malaise, anorexia, and arthralgia. (2) Classic thromboembolic and immunologic phenomena include Roth spots, Janeway lesions, Osler nodes, and splinter hemorrhages. Children, however, rarely exhibit these signs. Splenomegaly, petechiae, and new or changing murmur may be appreciated on physical examination. The Duke criteria form a clinical diagnostic aid that combines clinical, microbiologic, pathologic, and echocardiogram parameters and remains a useful tool in establishing the likelihood of IE. In contrast to adults, transthoracic echocardiogram is highly sensitive in children. (4)Blood cultures are an essential component of IE diagnosis. A minimum of 3 cultures should be taken from separate venipuncture sites on the first day of admission, followed by 2 to 3 further cultures the following day if no growth has been observed. (3) Clinicians should be aware that blood volumes drawn in the pediatric population are often well below recommended volumes for pathogen detection, thereby greatly decreasing the sensitivity of the test.The American Heart Association last updated its guidelines for management of IE in both children and adults in 2015. This document also includes antibiotic prophylaxis guidelines at times of potential bacteremia. For the case described herein, antibiotic prophylaxis would not have been recommended. In severely ill children, antibiotic therapy should be initiated immediately after the initial cultures are drawn; in stable patients, therapy can be deferred until an organism is cultured. Empiric therapy with vancomycin and gentamicin will provide coverage for the most likely organisms until results of culture and susceptibility testing are available. IE resulting from methicillin-susceptible staphylococci should be treated with a β-lactamase resistant penicillin (such as cloxacillin, oxacillin, or nafcillin). There is limited evidence for including an aminoglycoside to enhance bacterial killing; this must also be weighed against the risk of renal and ototoxicity. American Heart Association guidelines strongly recommend an infectious diseases consult and availability of cardiothoracic surgical services at the admitting institution. Treatment duration will range from 4 to 6 weeks in uncomplicated cases, depending on organism cultured and presence of prosthetic valves. Unlike adults, 2-week treatment durations are not recommended in children.

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