From the Guidelines
Bactericidal antibiotics, such as beta-lactams (ampicillin, cefotaxime) and aminoglycosides (gentamicin), are the preferred choice for treating newborns due to their ability to directly kill bacteria, which is crucial for their immature immune systems.
Bactericidal vs Bacteriostatic Drugs
The distinction between bactericidal and bacteriostatic drugs is critical in the context of newborns. Bactericidal drugs, which include beta-lactams (e.g., ampicillin, cefotaxime) and aminoglycosides (e.g., gentamicin), are preferred because they directly kill bacteria, whereas bacteriostatic drugs (e.g., macrolides, tetracyclines, chloramphenicol) only inhibit bacterial growth. This preference is based on the newborn's underdeveloped immune system, which may not be able to effectively clear bacteria that are merely inhibited by bacteriostatic agents 1.
Recommended Treatments
For empiric treatment of suspected neonatal sepsis, a common regimen includes ampicillin (50-100 mg/kg/dose IV every 12 hours) plus gentamicin (4-5 mg/kg/dose IV every 24-48 hours, depending on gestational age) 1. The dosing must be carefully adjusted based on gestational age, postnatal age, and renal function. It's also important to consider the use of a local antibiogram to guide antibiotic choices, especially when treating specific infections like urinary tract infections or bacterial meningitis 1.
Avoiding Certain Drugs
Certain bacteriostatic drugs should be avoided in neonates due to potential adverse effects. Tetracyclines should be avoided completely because they can cause dental staining and affect bone growth. Chloramphenicol requires careful monitoring due to the risk of "gray baby syndrome" resulting from immature hepatic metabolism. Fluoroquinolones are generally avoided due to concerns about their impact on cartilage development 1.
Key Considerations
The choice of antibiotic therapy in newborns must consider their unique physiology, including reduced drug metabolism and elimination, which necessitates careful dosing and monitoring of all antimicrobials. The preference for bactericidal agents over bacteriostatic ones is a key principle in managing infections in this vulnerable population, as emphasized by recent guidelines and studies 1.
From the FDA Drug Label
Gentamicin Injection, USP is indicated in the treatment of serious infections caused by susceptible strains of the following microorganisms: Pseudomonas aeruginosa, Proteus species (indole-positive and indole-negative), Escherichia coli, Klebsiella-Enterobacter-Serratia species, Citrobacter species and Staphylococcus species (coagulase-positive and coagulase-negative) Clinical studies have shown gentamicin injection to be effective in bacterial neonatal sepsis; bacterial septicemia and serious bacterial infections of the central nervous system (meningitis), urinary tract, respiratory tract, gastrointestinal tract (including peritonitis), skin, bone and soft tissue (including burns) Gentamicin injection may be considered as initial therapy in suspected or confirmed gram-negative infections, and therapy may be instituted before obtaining results of susceptibility testing In serious infections when the causative organisms are unknown, gentamicin injection may be administered as initial therapy in conjunction with a penicillin-type or cephalosporin-type drug before obtaining results of susceptibility testing
Ampicillin for Injection, USP, is used for Bacterial Meningitis and Septicemia in neonates Dosage should be based on Gestational age and Postnatal age according to Table 3 Treatment of all infections should be continued for a minimum of 48 to 72 hours beyond the time that the patient becomes asymptomatic or evidence of bacterial eradication has been obtained
Bacteriocidal and bacteriostatic drugs used in newborns include:
- Gentamicin: a bacteriocidal drug effective against gram-negative bacteria, used in the treatment of serious infections such as bacterial neonatal sepsis and septicemia 2
- Ampicillin: a bacteriocidal drug effective against a wide range of bacteria, including gram-positive and gram-negative bacteria, used in the treatment of bacterial meningitis and septicemia in neonates 3
From the Research
Bacteriocidal and Bacteriostatic Drugs
Bacteriocidal drugs kill bacteria, whereas bacteriostatic drugs inhibit the growth of bacteria. In newborns, the choice of bacteriocidal or bacteriostatic drugs depends on the type of infection and the susceptibility of the pathogen.
Commonly Used Antibiotics
- Ampicillin and gentamicin are commonly used as empiric therapy for suspected systemic infections in newborns 4, 5, 6.
- Cephalosporins, such as cefotaxime, can be used as an alternative to gentamicin, but their use has been associated with an increased risk of neonatal death 7.
- Carbapenems, such as piperacillin-tazobactam, can be used to treat infections caused by gram-negative bacteria 5.
- Vancomycin can be used to treat infections caused by methicillin-resistant Staphylococcus aureus (MRSA) 5.
Factors Influencing Antibiotic Choice
- Gestational age and birth weight can influence the choice of antibiotic and the dosage used 4.
- The susceptibility of the pathogen to different antibiotics can also influence the choice of antibiotic 5, 6.
- The clinical condition of the infant, such as the presence of sepsis or meningitis, can also influence the choice of antibiotic 8.