Bilateral Foot Infection as a Result of Peripheral Vascular Disease
Article Outline
- Abstract
- Pathophysiology
- Problem
- Presentation
- Clinical Diagnosis and Tests
- Clinical Management
- Understanding of the Disease Process
- Patient Education
- Conclusion
- References
- Copyright
Abstract
This case presentation describes a 37-year-old homeless man with peripheral vascular disease and mixed bacterial and fungal infections of the feet. His management is a challenge because of his homeless status and lack of hygiene. His history includes alcoholism and tobacco addiction, which complicate his plan of care because of the negative affects associated with both. After careful assessment, referral to a dermatologist, education, and treatment, his infections resolved.
Keywords: Bacterial dermal infection , fungal dermal infection , homeless , mixed dermal infections , peripheral vascular disease
A 37-year-old man presented to a local community clinic complaining of painful feet that had been bothering him for 2 months. The pain and swelling were so severe that he had to wear a pair of slippers, as his shoes would no longer fit his feet. He told the provider that he had been to the local emergency department (ED) two times in the past 8 weeks. He was given prescriptions for cephalexin and pain medication at both ED visits, then discharged each time. He told the health care provider that he was not taking any routine medications. His vital signs were: an oral temp of 98.7, pulse was 88, respirations were 20, blood pressure was 118/82, and body mass index was 30. As the interview continued, he reported that he consumed alcohol on a daily basis and that it was not unusual for him to have three to four drinks per day. He was very forthcoming when he was asked about the length of his drinking, and he acknowledged that this had been ongoing over the past 10 years. The patient also reported that he is a one to two pack per day smoker and that he began smoking when he was 18 years of age. He reported that his smoking habits had been fairly consistent for the past 10 to 12 years. He denied any current illicit drug use, but reported that he had smoked marijuana recreationally in the past. When asked about employment, the patient described working occasionally in construction. The patient reported that he had not been able to work for the past 6 weeks due to the pain in his feet, which limited his ability to walk. Questions about his living environment revealed that occasionally he would stay with relatives, but he considered himself homeless. He reported that he frequents shelters for a daily meal and a place to sleep, and occasionally sleeps under a bridge or in the park if he cannot find anything else.
During the examination, he was wearing extremely dirty slippers, which were removed. His feet were very edematous, erythematous, and had numerous scattered crusted lesions with purulent drainage; however, pulses were palpable and graded as two plus (+ +) bilaterally. The affected areas of the feet appeared to be mainly the soles, with some extension to the sides of the feet and between his toes. He had toenails that were notably thick and long, indicating poor foot care. His overall appearance was unkempt and his hair was unclean. In considering treatment of this patient, there were a number of issues regarding his situation and health status to understand.
Pathophysiology
Peripheral vascular system is a term used to describe the part of the circulatory system that supplies the skin and the extremities, particularly the legs and feet.1 Peripheral vascular disease (PVD) is defined as peripheral venous disease and peripheral arterial disease. Peripheral vascular disease is a marker for atherosclerosis, which affects blood vessels by obstructing blood flow. Atherosclerosis is the buildup of plaques and lipids on the blood vessel walls over time. If the plaque becomes injured, clots or thromboses may occur, which further obstruct blood flow. Other vascular problems such as embolism or aneurysms can occur independently or concurrently.2
Atherosclerosis is caused by low-density lipoproteins (LDLs) infiltrating the subendothelial region. Lipids tend to accumulate the most in areas where vessels branch, which begins the formation of atherosclerosis. Over time, LDLs are oxidized or altered in other ways, then taken up by macrophages to form foam cells. Foam cells form fatty streaks that affect vessel walls. Oxidized LDLs have a number of harmful effects, including stimulation to release cytokines and inhibition of nitric oxide production. Foam cells stimulate smooth muscle cells to move from the media of the vessel to the intima, where they add to the bulk of the lesion. Smooth muscle cells may also become foam cells by taking up the oxidized LDL.2 Lipid accumulation occurs intracellularly and extracellularly. A fibrous cap forms as plaques age. Plaques that have injured caps are the most likely to rupture. Plaque buildup alone can obstruct blood flow but an injured plaque resulting in clot formation can completely occlude a vessel.2
A history of extended tobacco and alcohol abuse increase the risk of peripheral vascular disease significantly. This patient does not drive; therefore, his feet are his primary mode of transportation. Smoking cigarettes causes a state of tissue hypoxia resulting in decreased blood flow and increased healing time. Nicotine, the pharmacologic active component of cigarette smoke, can lead to hypoxia and tissue damage. Inhaled tobacco smoke delays healing due to vasoconstriction, enzymatic system toxicity, and impaired epithelialization.3 Alcohol abuse has led to secondary nutrition deficits and inadequate water ingestion, which also caused delayed healing. Chronic alcohol abuse leads to impaired utilization of nutrients and increased degradation of nutrients by the liver, as well as gastric malabsorption resulting in malnutrition. Alcohol can impair vitamin levels such as thiamine, riboflavin, pyridoxine, ascorbic acid, folic acid, and beta carotene.4 Additionally, poor personal and environmental hygiene gives rise to opportunistic infections. The initial insult may have been mechanical, such as rubs and blisters caused by poor fitting shoes. After the skin integrity was compromised, the infectious process began.
The infectious process that occurred with this patient was twofold: bacterial and fungal. Bacterial skin infections are generally caused by gram-positive organisms. S. aureus is the organism that is commonly cultured from skin infections. S. aureus can become resistant to methicillin, resulting in an organism that is difficult to treat. The fungal co-infection added another infectious component that had to be treated and eradicated to allow proper healing.
Problem
Occlusive vascular disease affects 8 to 12 million United States residents and is a concerning cause of disability.5 The prevalence of lower extremity peripheral vascular disease is greatest in the older population over 75 years of age and is seen more in men than in women.6 Also, it has a higher occurrence among non-Hispanic blacks, followed by Mexican Americans, then non-Hispanic whites.6 The prevalence of peripheral vascular disease is increased by other comorbidities. According to Uphold and Graham, 80% to 90% of leg ulcerations are caused by venous insufficiency.7 Although considerably young, this case presents a number of risk factors for development of this chronic disorder.
The homeless spend the majority of their time continuously standing, sleeping upright, and exposed to the elements of outdoors and weather changes. They often have poorly fitting shoes, no clean socks, and maintain poor foot care. In addition, he smoked one to two packs of cigarettes a day and consumed alcohol daily for several years, which are two significant risk factors for PVD.8 Furthermore, PVD is commonly associated with long-term alcoholism. PVD can result in multi-end organ damage including hypertension, coronary artery disease (CAD), and renal failure.9 The lifestyle of a homeless person may lead to recurring problems such as leg ulcers, PVD, and cellulitis; which can progress to limb- and life-threatening infections.10
Presentation
Signs and symptoms of PVD can include pain in the affected extremity upon exertion that is relieved with rest. Numbness and tingling may occur in the affected extremity and toes of that extremity may burn or ache even with rest. Discoloration may appear and be intermittent or permanent. The affected extremity may feel cooler to touch, with possible decreased pedal pulses, and non-pitting edema. Lower extremity hair loss may be noted with PVD. A critical sign is a sore or lesion with delayed healing time on a lower extremity. Chant explains that there are differences in the characteristics of venous and arterial lower-extremity ulcers.11 Edema that occurs prior to the presence of an ulcer is formed under high pressure, causing tissue damage and severe tenderness, and is the earliest physical sign of PVD.7 Also, petechial hemorrhage may appear at the site of edematous skin and, once the edema has resolved, the skin may retain the brownish appearance from the remaining iron.7 The areas of ulceration are superficial and have shaggy borders with large amounts of exudates.7 Another common sign or symptom associated with PVD includes dermal problems of itching, redness, tenderness, scaling, and ulcerations. This type of dermatitis is prone to bacterial infections such as S. aureus; however, only half of these opportunistic infections are caused by a single organism.12 Therefore, culture and sensitivity are very important to properly diagnose the infecting bacterial organism.
Clinical Diagnosis and Tests
Differential Diagnosis
Differential diagnoses are considered for evaluation to help rule out any other cause of symptoms. Differential diagnoses for PVD can include:
Bacterial dermal infections including CAMRSA would be assessed by appearance and lab tests, including culture and sensitivity along with complete blood count (CBC) with differential. A gram stain may also prove useful in a preliminary diagnosis. Fungal dermal infection would also be assessed by appearance, along with obtaining skin scrapings to be examined by the lab. A Wood's light could also be used to examine the affected dermal area in a darkened room; however, most dermatophytes do not fluoresce. The exceptions are zoophilic dermatophytes.
Contact dermatitis would be assessed by appearance. Vesicles and erythema are often hallmark signs of contact dermatitis. Contact dermatitis may be harder to diagnose and may be a diagnosis primarily based on examination and exclusion of other diagnoses. Contact dermatitis can be divided into primary irritant contact dermatitis and allergic contact dermatitis. The most common irritant are soaps, detergents, solvents, and cement. The most common allergens causing allergic contact dermatitis are nickel, rubber products, topical medications, plant allergens, formaldehyde, hairdressing chemicals, and dyes—including shoe dyes.13 Therefore, assessment of exposures can help to rule out contact dermatitis. Inflammatory dermal response would be assessed by appearance along with CBC and erythrocyte sedimentation rate (ESR). Inflammatory dermal response may be a diagnosis of exclusion as well.
Deep vein thrombosis would be assessed by appearance, measurement of the affected extremity calf circumference, and color Doppler ultrasonography. Examination should include evaluation of a Homan's sign in the affected extremity. Bilateral appearance of lower extremity pain and swelling should be considered less likely for deep vein thrombosis when narrowing the diagnosis, although it is possible to have bilateral deep vein thrombosis, and therefore should be considered as a possible diagnosis.
Peripheral artery disease would be assessed by appearance and a hand-held Doppler to assess pedal pulses. Lower-extremity pulses would probably be diminished or nonpalpable unilaterally or bilaterally depending on the vessel involvement. Additional diagnostic tests include ankle brachial index, angiogram, and ultrasound Doppler test. Magnetic resonance angiography (MRA) has gained popularity because of its sensitivity and specificity. Homocysteine, fibrinogen, lipid profile, and high-sensitivity C-reactive protein may be helpful in making this diagnosis.14 Compromised immune system would be assessed by appearance and lab tests. Diagnostic tests would include human immunodeficiency virus (HIV) testing, hepatitis profile, syphilis test, and CBC with differential. A tuberculosis skin test may also be helpful, especially in a high-risk patient. A summary of clinical presentations and expected findings are shown in Table 1.
Table 1. Clinical Presentation and Expected Findings
| Bacterial dermal infection including: | |
| Community-acquired methicillin-resistant | Inspection: |
| Staphylococcus aureus (CAMRSA) | Edema, erythema, lesions, purulent drainage |
| Lab Evaluation: | |
| CBC – elevated white blood cell count | |
| Culture – positive culture* | |
| Gram stain – positive for bacteria* | |
| Fungal dermal infection | Inspection: |
| Edema, erythema, scaling, excoriation secondary to scratching, affected area may fluoresce in darkened room using a Wood's light | |
| Lab Evaluation: | |
| Skin scraping – positive for fungus | |
| Localized contact dermatitis | Inspection: |
| Erythema, edema, vesicles, blisters or bulla, serous drainage | |
| Inflammatory dermal response | Inspection: |
| Erythema, edema, popular patches | |
| Lab Evaluation: | |
| CBC – elevated white blood cell count | |
| ESR – elevated | |
| Deep vein thrombosis | Inspection: |
| Erythema in the affected area, edema may be difficult to assess, and the extremity should be measured and compared to the opposite side, positive Homan's sign | |
| Lab Evaluation: | |
| D-dimer – positive | |
| Imaging Evaluation: | |
| Doppler ultrasonography – positive | |
| Peripheral artery disease | Inspection: |
| Color changes – intermittent claudicating | |
| Lab Evaluation: | |
| Homocysteine – elevated | |
| Fibrinogen – elevated | |
| C-reactive protein – elevated | |
| Lipids (total cholesterol, low-density lipoprotein, and triglycerides) – elevated | |
| Imaging Evaluation: | |
| Angiogram – positive | |
| Doppler ultrasonography – positive | |
| MRA – positive | |
| Additional Evaluation: | |
| Ankle brachial index – decreased ankle pressure | |
| Extremity pulses – weak or no palpable | |
| Compromised immune system | Inspection: |
| Generalized weakness, generalized rash or lesions, pallor | |
| Lab Evaluation: | |
| HIV test – positive | |
| Hepatitis profile – positive | |
| Syphilis test – positive | |
| Tuberculosis skin test – positive | |
| CBC – elevated white blood cell count | |
* Probably a gram-positive cocci. |
Assessment is one of the key factors in helping to rule out differential diagnosis. Therefore, skin color, temperature, and pedal pulses must be taken into consideration, along with the appearance of the actual lesions on both feet, when formulating a differential diagnosis. Worley states that pulses in the feet and ankles are not considered an accurate indicator of venous stasis disease.15 However, pedal pulses and posterior tibial pulses should be assessed and used to help formulate the differential diagnoses. In addition, itching should be assessed to adequately formulate a comprehensive differential diagnosis list. Allen refers to intense itching as a symptom and positive finding for contact dermatitis.16 Intense itching can be an indicator for contact dermatitis when composing a differential diagnosis list.16 Patients complaining of itching should be evaluated for secondary excoriation of the skin due to scratching.
Narrowing the Diagnosis
In consideration of the information discussed, the presumptive diagnosis to consider would be bilateral lower-extremity PVD with secondary mixed infectious dermatitis. The diagnosis of PVD in this case is defined as venous. Diagnostic tests for PVD include Doppler flow studies.7 This patient was scheduled for vascular studies of bilateral lower extremities with color-flow Doppler at a local hospital. However, because of his homeless situation and being uninsured, he did not keep the appointment. The presenting patient's CBC showed a slightly elevated mean corpuscular volume (MCV) and white blood cells but was otherwise unremarkable. Another good indicator of infection and inflammation is an ESR,12 which was elevated in this patient. The patient's CMP showed a slightly elevated alanine transaminase (ALT) and aspartate aminotransferase (AST) without other abnormalities. His urinalysis was concentrated but was negative for glucose or protein, and considered otherwise unremarkable. Considering a history of homelessness and alcohol abuse, HIV testing and hepatitis profile should be obtained. Also, hepatitis can impact clotting factors, which are utilized in the inflammation process in response to infection.17 It is essential to obtain baseline liver function tests in patients admitting to regular alcohol intake before prescribing oral antifungal medications. Both of these laboratory tests were obtained in this patient, which were negative. For this patient, cultures were obtained for both bacterial identification and fungal identification. However, at the time of the visit, results were not available, as cultures require up to 72 hours for bacterial identifications and up to a week for fungal identification. Due to this, antibiotic and antifungal selection is usually limited to empiric treatment, but can be tailored once the infecting organism is identified.
Diagnosis
Initial evaluation should include a CBC with differential to explore the extent of the infection and to obtain a baseline of immunity by evaluating the white blood count (WBC) for leukocytosis. However, leukocytosis may be minimal or absent, as reported in one study that revealed only 53% of cases presented with an elevated WBC count.12 Also, a urinalysis and comprehensive metabolic profile (CMP), which evaluates glucose levels, and liver and kidney function, as well as electrolyte levels, should be considered as part of the lab evaluation. Abnormal findings in these areas are important to assess in order to understand underlying comorbidities that may impact treatment as well as selection of medications when prescribing antibiotics and antifungal medications. It is important to assess for HIV and hepatitis, as these affect the healing ability by suppressing the immune system and may prolong the treatment. With HIV, immunosuppression is the hallmark of the illness, which makes patients susceptible to opportunistic diseases and infections.12 A culture and sensitivity of the lesions should be done due to the significant history of lengthy symptoms and previous treatment with cephalexin without resolution. This will ensure that the choice of antibiotic or antifungal medication that is prescribed is appropriate for this case. The type of culture will depend on the severity of the infection, and whether the infection is considered nonlimb threatening or limb threatening. If there is a significant threat of loss of the limb, deep cultures should be obtained to avoid surface contamination; this type of culture will usually yield a mixture of aerobic anaerobic microorganisms.12 Infectious aerobes to consider include S. aureus, coagulase-negative staphylococci, streptococci, enterococci, and Enterobacteriaceas.12 Infectious anaerobes to consider include anaerobic streptococci, bacteroides, and clostridium species.12 Remembering the history given by the patient, resistant organisms must be a consideration, especially with CAMRSA. CAMRSA is being seen increasingly by providers in the community setting. It has been seen in increasing incidents in athletes, military recruits, children, Pacific Islanders, Alaskan Natives, Native Americans, men who have sex with men, and prisoners.18 In addition, there is a greater risk for those who have skin-to-skin contact, openings in the skin such as cuts or abrasions, contaminated items and surfaces, crowded living conditions, and poor hygiene.18
Clinical Management
Empiric treatment with broad-spectrum antibiotics is generally the common approach; however, it is becoming increasingly problematic with the increasing incidence of antimicrobial resistance.12 Until the organism is identified, for nonlimb threatening infections, treatment should be directed at both staphylococci and streptococci. Appropriate antibiotics directed at these organisms include oral cephalexin or clindamycin for 14 days.12 However, with the recent epidemic of resistant bacteria such as CAMRSA, antibiotics focused at MRSA should be considered initially, such as trimethoprim-sulfamethoxazole or doxycycline. Empiric intravenous therapy for involvement of cellulitis can include cefazolin, cefoxitin, cefotetan, clindamycin, ampicillin-sulbactam, or piperacillin-tazobactam. Empiric IV antibiotic therapy is usually short-term, approximately 3 days or until systemic symptoms are resolved, and then the patient will continue on oral mediations that are appropriate for the specific microorganism.12 For serious limb-threatening infections, broad-spectrum antibiotics are used. Choices include piperacillin-tazobactam, combination of ceftriaxone and clindamycin (or miconazole), combination of levofloxacin and clindamycin (or miconidazole), imipenem-cilastatin, or ampicillin-sulbactam.12 If resistant organisms are suspected, imipemen along with vancomycin should be considered for the treatment. Alternative antibiotics can also be used depending on the pattern of resistance, which can include not only vancomycin but also tigecycline, deptomycin, and linezolid. Choices will also be determined by the any comorbid hepatic or renal disorders. Once the antibiotic is tailored for the organism and the patient's comorbidities, continuous monitoring of the effects of the treatment would include weekly CBC, CMP, and ESR. In severe cases, a wound care specialist consult can be warranted for wound dressing recommendations and possible hyperbaric therapy. Other tests, such as a magnetic resonance imaging (MRI) or Indium scan should be considered to assess for osteomyelitis secondary to PVD.12
This patient was considered to have non-limb-threatening infection and was started on trimethoprim-sulfamethoxazole and continued on over-the-counter ibuprofen for pain. He was also referred to a dermatologist for evaluation and treatment for the dermatitis. The dermatologist diagnosed this patient with mixed bacterial and fungal infections of the bilateral lower extremities, and he was continued on trimethoprim-sulfamethoxazole, methylprednisolone, and antifungal topical treatment. Interestingly, he was also instructed to soak his feet twice a day in a clean foot tub using tepid tap water and two ounces of white vinegar, then to pat his feet dry and put on clean white socks until his follow-up visit at the community clinic in 1 week. At the follow-up visit, he was significantly improved. He was continued on antibiotics and antifungal therapy along with the water and vinegar soaks. Therapy was continued with weekly follow-up visits until the infection was completely resolved at week five.
Understanding of the Disease Process
To increase compliance, understanding of the disease process is important. Explain that peripheral artery disease is the hardening of vessels in the area of symptoms, which is caused by the build-up of plaques that block blood flow and that peripheral venous disease is caused by venous insufficiency or blood clots. It is always a good idea to have pictures to demonstrate this explanation visually; a picture can be worth a thousand words. Explain the importance of smoking cessation along with minimal alcohol consumption or abstinence. Because tobacco smoke causes vasoconstriction and alcohol consumption can cause poor nutrition, both circulation and nutrients are diminished, which is required for healing. When diagnosed with PVD, it is important to keep feet clean and dry, to wear clean socks with well-fitting shoes, and to assess and trim nails. Also, instructions should involve good hand washing, good general hygiene, and how to maintain a clean living environment for prevention of future infections. Openness about alcohol use can be an opportune time to get the dialogue started regarding treatment. A referral for treatment should be considered along with providing information for Alcoholics Anonymous.
Patient Education
When a patient presents with PVD, the provider has an opportunity to educate the patient on how to prevent such complications as secondary infections during this encounter. Instructions should be provided that are understandable to the patient, so it is important to keep it simple. In this case, it became apparent that the patient had difficultly reading and writing; with information given to the patient at his level of literacy, he was able follow through with compliance of his medication and instructions of wound care.
Patient education instructions for this patient were challenging due to his level of literacy, very limited income, alcohol abuse, tobacco abuse, lack of nutrition, and poor living conditions. He did not have a permanent place to reside and therefore was unable to maintain a clean living environment. This patient was encouraged to stay with family during the healing phase to help ensure a consistent living environment. He elected to stay with family only short-term because his family did not tolerate his use of alcohol. He was encouraged to seek rehabilitation services available through the local mental health facility.
Conclusion
This case demonstrated several issues that were addressed at the initial visit as well as follow-up visits, which lead to resolution of the infection. There was a significant lack of cleanliness and poor hygiene, along with poor nutrition, alcohol, and tobacco abuse. Also, due to his homeless situation, the patient did not follow-up with a number of diagnostic and community service referrals. Although he received education regarding the effects of tobacco and alcohol on his illness, he was reluctant to seek treatment through community services for these addictions. Although such occurrences may be the case with many patients, providers should always strive to offer all available resources to patients.
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- Begany T. Coagulation and inflammation: interrelated response to infection. Pulmonary Reviews.Com: Trends in Pulmonary and Critical Care Medicine. 2003; 8 (6). Available at: http://www.pulmonaryreviews.com/jun03/pr_jun03_coagulate.html. Accessed August 17, 2007.
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PII: S1555-4155(08)00019-6
doi:10.1016/j.nurpra.2008.01.017
© 2008 American College of Nurse Practitioners. Published by Elsevier Inc. All rights reserved.
