U – Urinary tract infections
Urinary tract infections (UTIs) are one of the most common bacterial infections seen in childhood. An understanding of the three categories of UTIs are useful for knowing the correct treatment and management (Tullus and Shaikh, 2020) (Table 1), and identifying the area affected also has an impact on treatment.
Table 1. Categories of UTIs
| Area | Condition | Common pathogen | Treatment |
|---|---|---|---|
| Febrile upper UTI | Acute pyelonephritis | Escherichia coli | Broad spectrum antibiotic 10 days |
| Lower UTI | Cystitis | Escherichia coli | Narrow spectrum antibiotic 3 days |
| Asymptomatic bacteruria | Escherichia coliKlebsiellaGroup B streptococci | Can be left untreated |
Bacteria is found in all UTI cases, with Escherichia coli (E. coli) detected in up to 90% of cases, originating from faecal flora, with vaginal flora also affected in girls. E.coli is a gram-negative bacillus, which is in the normal intestinal flora, causing intestinal and extra-intestinal disturbances.
Gram-negative bacteria show up as pink or red after gram testing. Gram testing (or staining) is used to differentiate between types of bacteria by looking at cell wall properties; gram-negative bacteria have thinner cell walls, typical of E. coli (Becerra et al, 2016).
Knowledge of the different antibiotics that are available is imperative, including those factoring in the type of UTI the patient presents with. Appropriate treatment is essential, but is challenging due to the increasing resistance to commonly prescribed antibiotics (e.g. amino-penicillins), and the increasing trend of multi-drug-resistant organisms that cause UTIs (Vazouras et al, 2020). Broad spectrum antibiotics increase the chances of covering and treat the causing pathogen, which results in the patient's recovery; yet, this does increase the overall expansion of antibiotic resistance (Diamant and Obolski, 2024). This has been demonstrated, for example, in Greece, where resistance to ampicillin and trimethoprim/sulfamethoxazole has been cited as high as 51% and 29%, respectively (Vazouras et al, 2020). Therefore, antibiotic therapy should ideally be prescribed with a more narrow spectrum antibiotic, which can be based on local sensitivity patterns (Daley et al, 2020) and local antibiotic resistance data from Public Health England (NICE, 2018a).
This then needs clinical diagnostics. Testing of urine is recommended if the child is symptomatic, and a sample should be taken prior to starting antibiotics, with a clean catch sample being preferred (RCGP, 2024). Urine samples should be dipstick tested (Davies et al, 2022), looking for traces of leukocytes and nitrites (Yates, 2016), and then sent for culture and microscopy.
Younger children and infants may need a referral to a paediatrician for further investigations and management. However, if a sample cannot be obtained and the child is at risk of further illness, then antibiotic therapy should not be delayed.
Although E. coli is the principle bacteria identified in UTIs, nitrofurantoin – a broad spectrum antibiotic – is still commonly used as resistance to E.coli is still low (Wijma et al, 2018), despite the call for more narrow spectrum antibiotic prescribing.
For uncomplicated lower UTIs in children aged from 3 months to 16 years, UK guidelines (NICE, 2018a) recommend either oral nitrofurantoin or trimethoprim as first-line treatment. If there is no improvement after 48 hours, nitrofurantoin can be prescribed. If not prescribed initially, amoxicillin if the culture is susceptible, or cefalexin. For upper UTIs – pyelonephritis – first-line treatment is cefalexin, or co-amoxiclav if the sensitivity is known (NICE, 2018b). Table 2 details the recommended oral medications, formulations, and descriptions.
Table 2. Antibiotics for UTIs
| Antibiotic | Formulations | Class | Subclass | Mechanism of action |
|---|---|---|---|---|
| Nitrofurantoin | TabletsCapsulesSuspension (25 mg/5 mL) | Nitrofurantoin | FuranesProtein synthesis inhibitor in the nucleus | |
| Trimethoprim | TabletsSuspension (50 mg/5 mL) | RNA synthesis inhibitors | Trimethoprim/sulphonides | Folic acid metabolism inhibitorInhibits bacteria DNA synthesis |
| Amoxicillin | CapsulesSuspension (250 mg/5 mL) | Penicillins | Aminopenicillins | Cell wall inhibitor |
| Cefalexin | TabletsCapsulesSuspension (125 mg/5 mL)(250 mg/5 mL) | Cephalosporins | 1st generation | Cell wall inhibitor |
| Co-amoxiclav | TabletsSuspension (125/31/5mL)(250/62/5mL)(400/57/5mL) | PenicillinsBeta lactam inhibitorClavulanic acid | Cell wall inhibitor |
Different antibiotics act on different areas of the cell. Cell wall inhibitors, for example, result in bacteria cell walls changing in shape and size, which induces a cellular stress response, resulting in cell lysis or cell death (Kohanski et al, 2010). Conversely, protein synthesis inhibitors in the cell's nucleus act on the ribosomes. Ribosomes convert genetic information in messenger RNA by making proteins and enzymes in the cell (Arenz and Wilson, 2016). Protein synthesis inhibitors, such as nitrofurantoin, trigger oxidative stress, which inhibits protein synthesis, resulting in cell damage.
It is evident that the antibiotics that are licensed for upper and lower UTIs in children are all broad spectrum antibiotics. Timely diagnosis and treatment is paramount, and can prevent long term side-effects, such as renal scarring, recurrent upper UTIs, impaired glomerular function, other renal diseases, and hypertension (Hay and Costelloe, 2013). Appropriate medications should be prescribed, which is dependent on a full examination of signs and symptoms and urinalysis.
Next in the series will be: V – Vitamin D.