A patient presents with cellulitis of the lower limb. Which ONE of the following is TRUE regarding cellulitis?
Answer: A:
Predisposing factors for cellulitis are:
The majority of cellulites are caused by grampositive bacteria, of which the most common pathogens are β-haemolytic streptococci (Staphylococcus pyogenes) and Staphylococcus aureus, and gram-negative aerobic bacilli. Aeromonas species are associated with fresh water exposure, whereas Vibrio species are seen in salt waterassociated infections. Pseudomonas is seen in infected burns, and mixed gram-negative and gram-positive aerobes and anaerobes in diabetic foot infections.
Most uncomplicated cases can be managed with outpatient antibiotics and supportive care including elevation of the affected part and addressing underlying causes; patient education is important. Certain patients should be treated aggressively including surgical debridement where needed; such patients include those with clenched fist injuries, orbital cellulitis and diabetic foot infections. Patients with diabetic foot infections will require anaerobic as well as aerobic cover. Suggested antibiotic regimes for mild–moderate diabetic foot infections include amoxicillin + clavulanic acid 875/125 mg po bd plus metronidazole 400 mg bd. For patients with penicillin hypersensitivity, ciprofloxacillin 500 mg bd plus clindamycin 600 mg tds can be given orally.
Often it is difficult to distinguish clinically between cellulitis and DVT, especially when the erythema overlaps the path of the deep veins in the leg. Additionally, laboratory tests may not be specific enough to help differentiate between the two disease entities; there are no diagnostic lab tests for DVT and the white cell count may be normal or elevated in both conditions. An ultrasound is therefore indicated if any doubt exists regarding the diagnosis.
References:
A 40-year-old childcare worker presents to the ED with 2 weeks of malaise and intermittent fevers. She has recently had a positive Mantoux test as part of a screening test for tuberculosis (TB) performed because her mother, who lives with her, has been diagnosed with TB and commenced on treatment.
Which ONE of the following is correct?
Answer: C: Primary TB occurs when mycobacterium tuberculosis (MTB) is transmitted via droplet infection to the lungs 224 CHAPTER 9 Infectious Diseases of a new host; some patients may be asymptomatic of primary TB but others manifest a pneumonitis similar to viral infection with fever, shortness of breath and possible chest pain. After a period of latent infection organisms proliferate; the lung apices are common sites of this reactivation due to their high oxygen content and blood flow.
A Mantoux test involves injection of purified protein derivative under the skin and measurement of the delayed hypersensitivity reaction generated; a positive reaction may indicate active or past infection or Bacille Calmette-Guérin (BCG) vaccination. Determining whether a patient who has a positive Mantoux test has active TB involves considering clinical features, microbiology and X-ray findings.
A positive early morning sputum smear is the best indicator of active infection; a chest X-ray may show typical features of reactivated pulmonary TB but the absence of findings is insufficient to rule out active infection that may be primary or reactivation (secondary). Patients do not need to be isolated if they do not have a productive cough.
You are involved in ensuring the hospital’s infection control policy is implemented in the ED and are planning an education session for medical and nursing staff in the ED.
Which ONE of the following is correct regarding infection control principles?
Answer: D: Standard precautions are used when caring for all patients and include handwashing, gloves, gowns, eye protection and masks, and when handling patient care equipment and linens, patient placement and environmental controls. Airborne precautions are used to prevent the transmission of infectious particles that may remain in the air and are dispersed widely by air currents, such as measles, varicella and TB. Patients with such illnesses should be placed in a negative pressure room with 6–12 air changes per hour from which the air is discharged to a high-efficiency filtration unit. HCW entering the patient’s room should wear N95 masks and if patient movement outside their room is unavoidable the patient should also wear N95 masks during transport. Droplet precautions are used to prevent transmission of infectious particles that are generated by coughing, talking or sneezing such as Neisseria meningitidis, streptococcus, influenza and pertussis. HCW should wear masks when within 1m of the patient, and patients should be in a private room or at least 1 m from other patients or visitors. Contact precautions are used to prevent transmission of infections spread by direct contact with the patient or equipment in their environment (e.g. multidrug resistant organisms, enterohaemorrhagic E. coli, respiratory syncytial virus (RSV), rotavirus, herpes simplex virus (HSV), impetigo scabies. Patients should be isolated in a single room and have their own dedicated multiuse equipment (e.g. BP cuffs); staff should wear gowns upon entering the room and discard these immediately before handwashing with antiseptic then leave the room.
Reference:
An ED resident comes to ask your advice on what antimicrobial treatment to start in the ED for a patient with a febrile illness of unknown source. The patient, a 62-year-old woman on sulfasalazine for rheumatoid arthritis, has a systemic inflammatory response.
Which ONE of the following is CORRECT?
Answer: C: Empiric antibiotic choice is important in the care of ED patients with significant illness. Principles involve the following:
It is most useful to commence broad-spectrum cover and to then narrow the spectrum once pathogen and sensitivities are known. Suggested empiric antibiotic therapy for adults with sepsis of unknown source includes:
The first dose of gentamicin does not need to be reduced in the setting of renal impairment; however, subsequent doses should be reduced and the dosing interval should be increased and guided by gentamicin levels. Fluoroquinolone absorption is reduced with concurrent administration of calcium and magnesium salts, and such ANSWERS 225 medications should not be given at the same time as the antibiotic.
A 17-year-old male presents to the ED with a 6-hour history of vomiting and profuse diarrhoea and blurred vision. He has no past medical history, medications or allergies and lives with two other college students, neither of whom have symptoms. On examination he is mildly dehydrated; he is unable to tolerate oral fluids due to difficulty in swallowing, and his power is 3/5 in the upper limbs and 4/5 in the lower limbs.
What is the most likely causative organism?
Answer: A: Food poisoning may be caused by viral (rotavirus, norovirus, astrovirus, enteric adenovirus) or bacterial pathogens. Most episodes of gastroenteritis due to food poisoning are self-limited and require only supportive care. Elderly patients, young children and the immunocompromised are more likely to have severe illness. Antibiotic therapy may be necessary in certain instances; the need is determined based on clinical symptoms and signs, disease severity, likelihood of resolution without antibiotics, and the suspected pathogen.
Botulism is caused by Clostridium botulinum associated with canned food, canned fish, and foods kept warm in dishes. Patients usually present with vomiting and diarrhoea but classically develop a descending, symmetric paralysis. The cranial nerves and bulbar muscles are first affected causing diplopia, dysarthria and dysphagia. Patients may report ‘blurred vision’. Adult patients require botulinum antitoxin while infant botulism is treated with botulinum immunoglobulin.
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