What antibiotics are effective against both gram-negative and gram-positive organisms?

From the Guidelines

The most effective antibiotics against both gram-negative and gram-positive organisms are carbapenems, such as meropenem and imipenem, due to their broad-spectrum activity and efficacy in treating severe infections, as recommended by the 2017 WSES guidelines for management of intra-abdominal infections 1.

When considering antibiotics for gram-negative and gram-positive coverage, several options are available, including:

• Carbapenems (meropenem, imipenem, ertapenem)
• Fluoroquinolones (ciprofloxacin, levofloxacin)
• Tetracyclines (doxycycline, minocycline)
• Aminoglycosides (gentamicin, amikacin)
• Certain cephalosporins (ceftriaxone, cefepime)
• Piperacillin-tazobactam
• Tigecycline
• Trimethoprim-sulfamethoxazole

The choice of antibiotic should be guided by the specific infection site, severity, local antibiotic resistance patterns, patient allergies, and potential side effects. It is essential to use broad-spectrum antibiotics judiciously to minimize resistance development, with narrowing of therapy once culture results are available.

In the context of intra-abdominal infections, the 2017 WSES guidelines recommend the use of carbapenems, such as meropenem and imipenem, as first-line treatment for severe infections, due to their broad-spectrum activity and efficacy in treating ESBL-producing Enterobacteriaceae and other resistant organisms 1. Additionally, the guidelines suggest that the use of carbapenems should be limited to preserve their activity and prevent the emergence of carbapenem-resistant strains.

It is crucial to note that antibiotic resistance patterns vary by region and institution, and local epidemiology should be considered when selecting empiric antibiotic therapy. The 2017 WSES guidelines emphasize the importance of a rational and appropriate use of antibiotics to optimize clinical care and reduce the selection pressure on resistant pathogens 1.

The dosing of antibiotics varies by specific infection, patient factors, and local resistance patterns. For example, meropenem is typically given as 1g IV every 8 hours, while ciprofloxacin is dosed at 500-750mg orally twice daily or 400mg IV every 12 hours.

These antibiotics work through different mechanisms, including:

• Carbapenems and cephalosporins: inhibit cell wall synthesis
• Fluoroquinolones: inhibit DNA gyrase
• Tetracyclines: block protein synthesis
• Aminoglycosides: bind to bacterial ribosomes

In summary, carbapenems, such as meropenem and imipenem, are the most effective antibiotics against both gram-negative and gram-positive organisms, due to their broad-spectrum activity and efficacy in treating severe infections, as recommended by the 2017 WSES guidelines for management of intra-abdominal infections 1.

From the FDA Drug Label

Levofloxacin has in vitro activity against Gram-negative and Gram-positive bacteria Aerobic bacteria Gram-positive bacteria Staphylococcus aureus (methicillin-susceptible isolates) Staphylococcus epidermidis (methicillin-susceptible isolates) Streptococcus pneumoniae (including multi-drug resistant isolates [MDRSP]) Streptococcus pyogenes Gram-Negative Bacteria Enterobacter cloacae Escherichia coli Haemophilus influenzae Haemophilus parainfluenzae Klebsiella pneumoniae Legionella pneumophila Moraxella catarrhalis Proteus mirabilis Pseudomonas aeruginosa Serratia marcescens

Effective antibiotics against both gram-negative and gram-positive organisms:

• Levofloxacin is effective against both gram-negative and gram-positive bacteria, including Staphylococcus aureus, Streptococcus pneumoniae, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa.
• Piperacillin and tazobactam is also effective against both gram-negative and gram-positive bacteria, including Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Key points:
• Levofloxacin has a broad spectrum of activity against both gram-negative and gram-positive bacteria.
• Piperacillin and tazobactam has a broad spectrum of activity against both gram-negative and gram-positive bacteria, including anaerobic bacteria. 2 3

From the Research

Effective Antibiotics for Gram-Negative and Gram-Positive Organisms

• Ceftriaxone is a broad-spectrum antibiotic effective against both Gram-positive and Gram-negative aerobic, and some anaerobic, bacteria 4.
• Levofloxacin is a fluoroquinolone antibacterial agent with a broad spectrum of activity against Gram-positive and Gram-negative bacteria and atypical respiratory pathogens 5.
• Other antibiotics that have been approved for treatment of MDR Gram-negative infections include β-lactam/β-lactamase inhibitor combinations, eravacycline, plazomicin, and cefiderocol 6.

Antibiotics for Specific Infections

• Ceftriaxone has been effective in treating infections due to multidrug-resistant Enterobacteriaceae, and has been used to treat complicated and uncomplicated urinary tract infections, lower respiratory tract infections, skin, soft tissue, bone and joint infections, bacteraemia/septicaemia, and paediatric meningitis due to susceptible organisms 4.
• Levofloxacin has been used to treat nosocomial pneumonia, community-acquired pneumonia, exacerbations of chronic bronchitis, acute maxillary sinusitis, uncomplicated and complicated urinary tract infections, and uncomplicated and complicated skin infections 5.

Revived and Newer Antimicrobial Agents

• Certain antibiotics such as colistin, fosfomycin, temocillin, and rifampicin have been revived to tackle the menace of superbugs, including members of Enterobacteriaceae, Acinetobacter species, and Pseudomonas species 7.
• Newer antibiotics are being developed to fill the gap of limited availability of drugs, with the initiative of Infectious Disease Society of America to develop 10 novel antibiotics against gram-negative bacilli by 2020 7.