Which Neisseria species, besides Neisseria gonorrhoeae, produce beta‑lactamase?

Beta-Lactamase Production in Neisseria Species

Beta-lactamase production has been documented in Neisseria meningitidis and several commensal Neisseria species through plasmid transfer from N. gonorrhoeae, though this remains rare in clinical practice.

Documented Beta-Lactamase Transfer to Other Neisseria

Neisseria meningitidis

• N. meningitidis can acquire beta-lactamase plasmids from N. gonorrhoeae through conjugation, though transfer frequencies are relatively low (10⁻¹ to 10⁻⁹) 1
• High-level penicillin resistance due to beta-lactamase production has been described in N. meningitidis but remains rare 2
• The primary mechanism of penicillin resistance in meningococci is alterations in penicillin-binding proteins rather than beta-lactamase production 2

Commensal Neisseria Species

Research has demonstrated beta-lactamase plasmid transfer from N. gonorrhoeae to multiple commensal species 3:

• Neisseria cinerea: 3 of 5 strains tested showed detectable conjugation frequencies and was the only species able to maintain the gonococcal conjugal plasmid (pLE2451) 3
• Neisseria flava: 2 of 5 strains accepted beta-lactamase plasmids 3
• Neisseria subflava: 1 of 3 strains demonstrated plasmid transfer 3
• Neisseria mucosa: 1 of 5 strains showed conjugation 3
• Neisseria perflava/sicca: 1 of 7 strains accepted plasmids 3
• Neisseria flavescens: 0 of 1 strain tested (insufficient data) 3

Clinical Significance and Reservoir Potential

• N. cinerea represents the most concerning potential reservoir because it not only accepts beta-lactamase plasmids but can also transfer them back to N. gonorrhoeae at high frequency 3
• The 4.4- and 3.2-megadalton beta-lactamase plasmids can be transferred between gonococcal and commensal species, raising concerns about nonpathogenic bacteria serving as resistance reservoirs 1, 3
• Beta-lactamase-producing N. gonorrhoeae can package these enzymes into outer membrane vesicles (OMVs), which can protect otherwise susceptible strains from beta-lactam antibiotics 4

Important Caveats

• Laboratory detection requires specific testing conditions: Beta-lactamase production in Neisseria species is more reliably detected using definitive tests such as nitrocefin-based techniques rather than standard MIC testing 2
• Standard inoculum density in susceptibility testing may result in MICs only slightly elevated compared to susceptible strains, potentially missing beta-lactamase producers 2
• The clinical relevance of beta-lactamase transfer to commensal Neisseria remains uncertain, as most documented cases are from experimental conjugation studies rather than clinical isolates 1, 3

Contrast with Other Respiratory Pathogens

Unlike Neisseria species where beta-lactamase production is rare, beta-lactamase production is common in other respiratory pathogens:

• Haemophilus influenzae: 25-50% of non-typeable strains produce beta-lactamase 2
• Moraxella catarrhalis: Up to 97.8% of clinical isolates produce beta-lactamase 2