Which medications in the drug class Antibiotic Agents are used in the treatment of Chorioamnionitis?

Updated: May 08, 2018
  • Author: Fayez M Bany-Mohammed, MD; Chief Editor: Ted Rosenkrantz, MD  more...
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Answer

Antibiotic Agents

Empiric antimicrobial therapy must be comprehensive and should cover all likely pathogens that cause early-onset sepsis (EOS). Antibiotic combinations are usually recommended for group B Streptococcus (GBS), listeria and serious gram-negative bacillary infections. This approach ensures coverage for a broad range of organisms and polymicrobial infections. In addition, it prevents resistance in bacterial subpopulations and provides additive or synergistic effects. Once organisms and sensitivities are known, the use of antibiotic monotherapy is then recommended. The exception would be bacteria that could be more susceptible to killing with the synergistic action of two antibiotics (eg, enterococcus).

Information about antimicrobials used to treat neonates and the source for this review is the Lexicomp Pediatric & Neonatal Dosage Handbook, 24th edition. [141] Another source for neonatal drug information is NeoFax, which is no longer available in the print form but is available online through subscription with Micromedex or via an application (app) through a tablet computer or smart phone.

Aqueous crystalline penicillin G is considered the first-line agent for GBS. Ampicillin may be used; however, there is concern surrounding the emergence of ampicillin-resistant E coli infections. Other modified penicillins such as oxacillin or nafcillin (antistaphylococcal), netilmicin (antipseudomonal or other gram-negative enteric bacteria), and piperacillin (antipseudomonal) are not typically used as first-line antibiotics for treatment of early-onset neonatal infections. The aforementioned modified penicillins are designed to treat infections caused by penicillin-resistant bacteria that can express beta-lactamase. These modified penicillins are usually reserved for the treatment of postnatally acquired infections in hospitalized neonates. Methicillin-resistant staphylococcal infections are uncommon causes of EOS; neonates with EOS who have these staphylococci reported should be treated with vancomycin.

Penicillin G, aqueous crystalline (Pfizerpen)

Aqueous crystalline penicillin G (pen G) administered IV is the drug of choice for GBS bacteremia or meningitis. Pen G is also known as benzylpenicillin. Do not confuse pen G with benzathine or procaine penicillin used only for IM injections; pen G is the original antibiotic in the penicillin class and inhibits synthesis of the bacterial cell wall. Pen G may provide adequate coverage for S pneumoniae when it is a cause of early-onset bacterial infection in neonates (infrequent) but this bacterium can also have resistance to pen G.

Ampicillin

A more broad-spectrum aminopenicillin used for many years as either a definitive or a prophylactic therapy for early-onset bacterial infection of neonates (ie, GBS, Listeria monocytogenes and susceptible E coli). Ampicillin may provide additional coverage against Haemophilus species, many enterococci, other streptococci, and a limited number of susceptible gram-negative enteric bacteria. It is indicated for neonatal bacteremia or meningitis due to GBS (pen G is the drug of choice). 

Cefotaxime (Claforan)

Cefotaxime is a third-generation cephalosporin with enhanced potency against many gram-negative bacteria. It is generally considered inactive against enterococci, Listeria, and most strains of pseudomonads and bacteroides. Some experts consider this antibiotic the preferred therapy for neonatal meningitis caused by gram-negative bacteria if the bacterium is sensitive to it (and in conjunction with an aminoglycoside). This preference is based on more effective CNS penetration of cefotaxime. Cefotaxime is indicated when aminoglycosides may be contraindicated (eg, significant renal failure) or when aminoglycosides may have enhanced toxicity. 

Gentamicin

Gentamicin is one of the aminoglycoside antibiotics (others include amikacin, netilmicin, kanamycin and tobramycin). Generally, gentamicin has activity against Pseudomonas aeruginosa, whereas kanamycin does not. Gentamicin is the first choice for prophylactic or definitive therapy of early-onset bacterial infections in neonates because it has broad activity against many gram-negative bacilli. Amikacin and tobramycin are usually reserved to treat nosocomial infections caused by gram-negative bacteria that are resistant to gentamicin.

Aminoglycosides should not be used alone to treat infections potentially caused by gram-positive bacteria. Thus, ampicillin is always included in the treatment of early-onset bacterial infections in neonates. Furthermore, to prevent the emergence of highly antibiotic-resistant gram-negative bacteria, nosocomial infections in hospitalized neonates should never be treated with an aminoglycoside alone. A second antibiotic should be administered in addition to the aminoglycoside, and its mechanism of action that causes microbial death should be different from that of the aminoglycoside.

This antibiotic has a black box warning. Elevated blood concentrations of aminoglycosides may cause significant injury to the kidney and the vestibular/auditory nerve. Concurrent use of furosemide or other loop diuretics and use of vancomycin can increase nephrotoxicity. Thus, trough levels of aminoglycosides in neonatal sera must be measured if their use is going to exceed an initial period of prophylaxis (ie, 48 h after birth) to exclude sepsis.

Aminoglycosides demonstrate concentration-dependent killing of bacteria, suggesting a benefit related to higher serum concentrations that are achieved with less-frequent dosing (eg, once daily administration is now the standard of care in term or late-preterm infants). 


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