Antibiotics and Infectious disease
Key points
Antibiotic mechanisms
Penicillins, Cephalosporins, Carbapenems: β lactam - binds to DD-transpeptidase - stops cross linking of peptidoglycans- inhibits cell wall synthesis
Glycopeptides - inhibits cell wall peptidoglycan cross linking - inhibits cell wall synthesis. Also affects RNA synthesis
Aminoglycosides, Tetracycline - inhibits protein synthesis - binds to 30S ribosomal subunit
Macrolides (clarithromycin, erythromycin), Lincosamides - inhibits protein synthesis - binds to 50S ribosomal subunit
Quinolones (Ciprofloxacin) - Block DNA replication by acting on topoisomerase IV
Nitroimidazole - (Metronidazole, tinidazole) - Induces DNA damage
Diaminopyrimidines (Trimethoprim) - inhibits dihydrofolate reductase - inhibits bacterial DNA synthesis
Nitrofurans - induces DNA damage
Gentamicin doses
Neonate <7 days - 5mg/kg/36h
>7 days - 28 days - 5mg/kg/24h
Over 28 days - 7mg/kg/24h
8 hourly regimen -
1 month-11 years - 2.5mg/kg
>11 years - 2mg/kg
Infectious diseases
Cat scratch disease
Bartonella henselae
Pre auricular, submandibular and cervical lymphadenopathy - suppurative in 10%
Can have spleen, liver, CNS involvement
Most cases self-limiting: 1-4 months
Mycobacterium tuberculosis
M. Tuberculosis, M Bovis, M Africanum
Acid fast bacilli, Ziehl Neelsen staining - culture may take weeks
TB is important differential for lymphadenopathy
Primary infection site is often the lungs
Cavitating apical lung lesion, pleural effusion, hilar lymphadenopathy
Horner's syndrome, pneumothorax and empyema can be complications
Other systems affected:
CNS + spine
GI - Ileocaecal disease
MSK - Joint abscesses
Send pus/sputum samples for histology and culture - Caseating granulomas are classical
Treatment: RIPE (Rifampicin, Isoniazid, Pyrazinamide, Ethambutol)
Mycobacterium avium complex
M. avium and M. Intracellulare
Common age 1-4
Collarstud abscess - purple in colour with multiple discharging sinuses
LN biopsy: PCR + culture
Necrotising granulomatous inflammation with various degrees of caseation
Management: Complete surgical excision
If not possible: 6-12 months clarithromycin, rifampin and ethambutol or rifampin + azithromycin
Myocarditis
Common cause is Cocksackie B virus, but this is often subclinical
Other viral causes are Parvovirus, and Herpes Virus 6
Page edited by Mrs Charnjit Seehra BSc November 2024
References
Kapoor G et al. Action and resistance mechanisms of antibiotics: A guide for clinicians. J Anaesthesiol Clin Pharmacol. 2017 Jul-Sep;33(3):300-305. doi: 10.4103/joacp.JOACP_349_15. PMID: 29109626; PMCID: PMC5672523.
British National Formulary for Children
Baranowski K, Huang B. Cat Scratch Disease. [Updated 2023 Jun 12]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing
Baerg, Joanne E, et al. "Lymphadenopathy." Pediatric Surgery NaT, American Pediatric Surgical Association, 2021. Pediatric Surgery Library, www.pedsurglibrary.com/apsa/view/Pediatric-Surgery-NaT/829685/all/Lymphadenopathy.
https://patient.info/doctor/tuberculosis-pro
Kang M, Chippa V, An J. Viral Myocarditis. [Updated 2023 Nov 20]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing