Australian Doctor 15th September 2023 AD 15th Sept Issue | Page 28

15 SEPTEMBER 2023 ausdoc . com . au organ systems and cause subacute bacterial endocarditis .

Consider other causes of arthritis , such as septic or gouty arthritis and trauma , particularly in a monoarthritis . Joint aspiration with a cell count , microscopy for the presence of organisms and crystals , and bacterial culture will often aid in differentiating between causes . For patients with carditis , the most common causes are viruses , such as enterovirus ( coxsackie group B ); adenovirus , Epstein – Barr virus ; CMV ; and various other viruses .

Consider non-infectious causes in those with unexplained symptoms , particularly those who have not fulfilled the epidemiological criteria rendering them at risk of Lyme disease . Conditions such as fibromyalgia and chronic fatigue syndrome manifest with chronic myalgias , fatigue , tenderness and sleep disturbances . These syndromes , as well as DSCATT , are often considered after unrevealing investigations for other differential diagnoses .

MANAGEMENT

PROPHYLACTIC antibiotics ( single dose of oral doxycycline 200mg for adults and 4.4mg / kg for children , up to 200mg ) are recommended by the Infectious Diseases Society of America ( IDSA ) within 72 hours for patients with a tick bite from an Ixodes sp ., where the bite occurred in an endemic area for B . burgdorferi sl and the tick was attached for longer than 36 hours . 18 In patients with a tick bite who develop erythema migrans , the IDSA and National Institute for Health and Care Excellence ( NICE ) UK guidelines recommend treatment with oral antibiotics , such as doxycycline ( 100mg bd or 200mg mane ) for 10-21 days , amoxicillin ( 1g tds ) or cefuroxime for 14-21 days or azithromycin

18 , 24

( 500mg mane ) for 17 days .

Disseminated and late Lyme disease require more prolonged therapy . IDSA and NICE UK guidelines recommend IV therapy as first line for neuroborreliosis . For Lyme disease affecting the brain or spinal parenchyma , IV ceftriaxone ( 2g bd ) with an oral alternative of doxycycline ( 100mg bd or 200mg mane ) for 14-21 days is recommended . In those with disease affecting the cranial nerves or peripheral nerves , either IV ceftriaxone ( 2g bd ) or oral

Ltshears / CC BY-SA 3.0 / bit . ly / 3WEp0Oh

Grook Da Oger / CC BY-SA 3.0 / bit . ly / 2I9WlOU

Figure 7 . Ringworm .

Figure 8 . Erythema multiforme . doxycycline ( 100mg bd or 200mg mane ) for 14-21 days can be used . Lyme carditis may be treated with oral doxycycline ( 100mg bd or 200mg mane ), amoxicillin ( 1g tds ), cefuroxime , or azithromycin ( 500mg mane ) for 14 to 21 days . If conduction abnormalities require hospitalisation , then IV ceftriaxone ( 2g mane ) for 14-21 days is preferred over oral antibiotics .

Prolonged oral therapy — such as doxycycline ( 100mg bd or 200mg mane ) or amoxicillin ( 1g tds ) for 28 days is recommended for Lyme arthritis . In those with a partial response after the first course of antibiotics , a second course of oral antibiotics could be considered ( doxycycline or amoxicillin ). In those with little or no response , IV ceftriaxone ( 2g mane ) for 2-4 weeks is recommended . 18 Refractory Lyme arthritis requires referral to a rheumatologist for further investigation and possible immunomodulatory therapy .

In patients who are bitten by a tick in Australia , prophylactic antibiotics for Lyme disease are not required as there are no B . burgdorferi sl – infected Ixodes sp . ticks found locally . Local reactions from tick bites occur often but usually resolve quickly with symptomatic treatment only , if needed .

In those who develop acute infective symptoms with fever , arthralgia and rash , Australian therapeutic guidelines recommend prompt treatment with oral doxycycline ( 100mg bd ) for seven days to treat likely rickettsial infection .

In patients with Lyme disease – like illness or DSCATT , aim management at supportive therapy , with analgesia , appropriate investigation into new symptoms and consideration of mental health strategies to assist the patient to cope with their medically unexplained symptoms .

It is important to avoid harmful additional investigations and treatments that may be detrimental without known benefits . For example , the use of prolonged IV ceftriaxone has been shown , in multiple animal studies , to change gut microbiota and immune function , with one case report describing ceftriaxone-induced immune haemolytic anaemia during inappropriate treatment with prolonged IV ceftriaxone . 25-27 The DSCATT clinical pathway is a useful tool to