The MtrCDE Efflux Pump Contributes to Survival of Neisseria gonorrhoeae From Human Neutrophils and Their Antimicrobial Components

Handing, Jonathan W.; Ragland, Stephanie A.; Bharathan, Urmila V.; Criss, Alison K.

doi:10.3389/fmicb.2018.02688

Cited by 47 publications

(52 citation statements)

References 60 publications

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“…To the best of our knowledge, the immediate pattern of exocytosis of human neutrophil granules is unique to M. smegmatis. While other bacteria have been shown to block or induce degranulation of some or all neutrophil granule subtypes [32,[49][50][51][52][53][54][55][56][57][58][59], release of only gelatinase granules at early time points has not been seen with bacteria other than M. smegmatis. An important distinction is that M. smegmatis is not preventing granule release to other stimuli, since granule mobilization was not affected upon fMLF stimulation by human neutrophils cultured with M. smegmatis.…”

Section: Discussionmentioning

confidence: 99%

Human Neutrophil Granule Exocytosis in Response to Mycobacterium smegmatis

et al. 2020

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Mycobacterium smegmatis rarely causes disease in the immunocompetent, but reported cases of soft tissue infection describe abscess formation requiring surgical debridement for resolution. Neutrophils are the first innate immune cells to accumulate at sites of bacterial infection, where reactive oxygen species and proteolytic enzymes are used to kill microbial invaders. As these phagocytic cells play central roles in protection from most bacteria, we assessed human neutrophil phagocytosis and granule exocytosis in response to serum opsonized or non-opsonized M. smegmatis mc2. Although phagocytosis was enhanced by serum opsonization, M. smegmatis did not induce exocytosis of secretory vesicles or azurophilic granules at any time point tested, with or without serum opsonization. At early time points, opsonized M. smegmatis induced significant gelatinase granule exocytosis compared to non-opsonized bacteria. Differences in granule release between opsonized and non-opsonized M. smegmatis decreased in magnitude over the time course examined, with bacteria also evoking specific granule exocytosis by six hours after addition to cultured primary single-donor human neutrophils. Supernatants from neutrophils challenged with opsonized M. smegmatis were able to digest gelatin, suggesting that complement and gelatinase granule exocytosis can contribute to neutrophil-mediated tissue damage seen in these rare soft tissue infections.

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Section: Discussionmentioning

confidence: 99%

Human Neutrophil Granule Exocytosis in Response to Mycobacterium smegmatis

et al. 2020

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“…The relative frequency of the mtrC LOF mutations we observe (occurring in approximately 1 in every 25 isolates) thus seems unusual for a mutation predicted to be deleterious for human infection. mtrC LOF strains do not grow more or less quickly in vitro than mtrC wild-type strains, indicating that this mutation does not confer a simple fitness benefit due to reduced energetic cost 31, 34 . Instead, we hypothesized that there are unique environments that select for non-functional efflux pump.…”

Section: Loss Of the Mtrcde Efflux Pump Is Associated With Cervical Imentioning

confidence: 98%

“…The MtrCDE pump has been demonstrated to play a critical role in gonococcal survival in the presence of human neutrophils and in the female murine genital tract model of gonococcal infection, and overexpression of mtrCDE results in substantial fitness benefits for dealing with both antimicrobial and environmental pressures 34–37 . The relative frequency of the mtrC LOF mutations we observe (occurring in approximately 1 in every 25 isolates) thus seems unusual for a mutation predicted to be deleterious for human infection.…”

Section: Loss Of the Mtrcde Efflux Pump Is Associated With Cervical Imentioning

confidence: 99%

Increased antibiotic susceptibility inNeisseria gonorrhoeaethrough adaptation to the cervical environment

Mortimer

Hicks

et al. 2020

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28Neisseria gonorrhoeae is an urgent public health threat due to rapidly increasing incidence and 29 antibiotic resistance. In contrast with the trend of increasing resistance, clinical isolates that 30 have reverted to susceptibility regularly appear, prompting questions about which pressures 31 compete with antibiotics to shape gonococcal evolution. Here, we used genome-wide 32 association on the largest collection of N. gonorrhoeae isolates to date (n=4882) to identify loss-33 of-function (LOF) mutations in the efflux pump mtrCDE operon as a mechanism of increased 34 antibiotic susceptibility and demonstrate that these mutations are overrepresented in cervical 35 isolates relative to urethral isolates (odds ratio (OR) = 3.74, 95% CI [1.98-6.70]). In support of a 36 model in which pump expression incurs a fitness cost in this niche, cervical isolates were also 37 enriched relative to urethral isolates in LOF mutations in the mtrCDE activator mtrA (OR = 8.60,) and in farA, a subunit of the FarAB efflux pump (OR = 6.25, 95% CI [3.90-39 9.83]). In total, approximately 1 in 3 cervical isolates (36.4%) contained a LOF mutation in either 40 the efflux pump components mtrC or farA or the activator mtrA. Our findings extend beyond N. 41 gonorrhoeae to other Neisseria: mtrC LOF mutations are rare (<1%) in the primarily 42 nasopharyngeal-colonizing N. meningitidis in a collection of 14,798 genomes but enriched in a 43 heterosexual urethritis-associated lineage (8.6%, p = 9.90×10 -5 ), indicating that efflux pump 44 downregulation contributes broadly to the adaptation of pathogenic Neisseria to the female 45 urogenital tract. Overall, our findings highlight the impact of integrating microbial population 46 genomics with host metadata and demonstrate how host environmental pressures can lead to 47 increased antibiotic susceptibility. 48 49 50 51Neisseria gonorrhoeae is the causative agent of the sexually transmitted disease gonorrhea. 52Antibiotics have played a key role in shaping gonococcal evolution 1-3 , with N. gonorrhoeae 53 gaining resistance to each of the first line antibiotics used to treat it 4-6 . As N. gonorrhoeae is an 54 obligate human pathogen, the mucosal niches it infects-most commonly including the urethra, 55 cervix, pharynx, and rectum-must also influence its evolution 7 . The gonococcal phylogeny 56 suggests the interaction of these factors, with an ancestral split between a relatively drug-57 susceptible lineage circulating primarily in heterosexuals and a relatively drug-resistant lineage 58 circulating primarily in men who have sex with men 3 . 59 60 Despite the deeply concerning increase in antibiotic resistance reported in gonococcal 61 populations globally 8 , some clinical isolates of N. gonorrhoeae have become more susceptible 62 to antibiotics 9,10 . This unexpected phenomenon prompts questions about which environmental 63 pressures could be drivers of increased susceptibility and the mechanisms by which 64 suppression or reversion of resistance may occur. To address these questions, we analy...

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“…The relative frequency of the mtrC LOF mutations we observe (occurring in~1 in every 25 isolates) thus seems unusual for a mutation predicted to be deleterious for human infection. mtrC LOF strains do not grow more or less quickly in vitro than mtrC wild-type strains, indicating that this mutation does not confer a simple fitness benefit due to reduced energetic cost 22,26,30 . Instead, we hypothesized that there are unique environments that select for non-functional efflux pump.…”

Section: Resultsmentioning

confidence: 99%

Adaptation to the cervical environment is associated with increased antibiotic susceptibility in Neisseria gonorrhoeae

et al. 2020

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Neisseria gonorrhoeae is an urgent public health threat due to rapidly increasing incidence and antibiotic resistance. In contrast with the trend of increasing resistance, clinical isolates that have reverted to susceptibility regularly appear, prompting questions about which pressures compete with antibiotics to shape gonococcal evolution. Here, we used genome-wide association to identify loss-of-function (LOF) mutations in the efflux pump mtrCDE operon as a mechanism of increased antibiotic susceptibility and demonstrate that these mutations are overrepresented in cervical relative to urethral isolates. This enrichment holds true for LOF mutations in another efflux pump, farAB, and in urogenitally-adapted versus typical N. meningitidis, providing evidence for a model in which expression of these pumps in the female urogenital tract incurs a fitness cost for pathogenic Neisseria. Overall, our findings highlight the impact of integrating microbial population genomics with host metadata and demonstrate how host environmental pressures can lead to increased antibiotic susceptibility.

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The MtrCDE Efflux Pump Contributes to Survival of Neisseria gonorrhoeae From Human Neutrophils and Their Antimicrobial Components

Cited by 47 publications

References 60 publications

Human Neutrophil Granule Exocytosis in Response to Mycobacterium smegmatis

Human Neutrophil Granule Exocytosis in Response to Mycobacterium smegmatis

Increased antibiotic susceptibility inNeisseria gonorrhoeaethrough adaptation to the cervical environment

Adaptation to the cervical environment is associated with increased antibiotic susceptibility in Neisseria gonorrhoeae

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