Infectious Disease

Infectious Disease Publications

Barros EM, Martin MJ, Selleck EM, Lebreton F, Sampaio JLM, Gilmore MS. Daptomycin Resistance and Tolerance Due to Loss of Function in Staphylococcus aureus dsp1 and asp23. Antimicrob Agents Chemother 2019;63(1)Abstract
Lipopeptide daptomycin is a last-line cell-membrane-targeting antibiotic to treat multidrug-resistant Alarmingly, daptomycin-resistant isolates have emerged. The mechanisms underlying daptomycin resistance are diverse and share similarities with resistances to cationic antimicrobial peptides and other lipopeptides, but they remain to be fully elucidated. We selected mutants with increased resistance to daptomycin from a library of transposon insertions in sequent type 8 (ST8) HG003. Insertions conferring increased daptomycin resistance were localized to two genes, one coding for a hypothetical lipoprotein (SAOUHSC_00362, Dsp1), and the other for an alkaline shock protein (SAOUHSC_02441, Asp23). Markerless loss-of-function mutants were then generated for comparison. All transposon mutants and knockout strains exhibited increased daptomycin resistance compared to those of wild-type and complemented strains. Null and transposon insertion mutants also exhibited increased resistance to cationic antimicrobial peptides. Interestingly, the mutant also showed increased resistance to vancomycin, a cell-wall-targeting drug with a different mode of action. Null mutations in both and resulted in increased tolerance as reflected by reduced killing to both daptomycin and vancomycin, as well as an increased tolerance to surfactant (Triton X-100). Neither mutant exhibited increased resistance to lysostaphin, a cell-wall-targeting endopeptidase. These findings identified two genes core to the species that make previously uncharacterized contributions to antimicrobial resistance and tolerance in .
Ung L, Bispo PJM, Shanbhag SS, Gilmore MS, Chodosh J. The Persistent Dilemma of Microbial Keratitis: Global Burden, Diagnosis, and Antimicrobial Resistance. Surv Ophthalmol 2018;Abstract
Microbial keratitis (MK) is a potentially blinding condition which must be treated emergently to preserve vision. Although long recognized as a significant cause of corneal blindness, our understanding of its true global scale, associated burden of disease, and etiological patterns remains somewhat limited. Current epidemiological data suggests that MK may be epidemic in parts of the world--particularly within South, South-East and East Asia--and may exceed two million cases per year world-wide. Etiological patterns vary between economically developed and developing countries, with bacterial predominance in the former and fungal predominance in the latter. The key to effective management lies in timely diagnosis; however, the current gold standard of stain and culture remains time consuming and often yields no clinically useful results. For this reason, there are attempts to develop highly sensitive and accurate molecular diagnostic tools to provide rapid diagnosis, inform treatment decision making, and minimize the threat of antimicrobial resistance. We provide an overview of these key areas and of avenues for further research toward the goal of more effectively addressing the problem of MK on both an individual and public health level.
Ismail AM, Cui T, Dommaraju K, Singh G, Dehghan S, Seto J, Shrivastava S, Fedorova NB, Gupta N, Stockwell TB, Halpin R, Madupu R, Heim A, Kajon AE, Romanowski EG, Kowalski RP, Malathi J, Therese KL, Madhavan HN, Zhang Q, Ferreyra LJ, Jones MS, Rajaiya J, Dyer DW, Chodosh J, Seto D. Author Correction: Genomic analysis of a large set of currently-and historically-important human adenovirus pathogens. Emerg Microbes Infect 2018;7(1):208.Abstract
The original publication of this article [1] was missing the below author that made contributions to the research and the published article.
Wurster JI, Bispo PJM, Van Tyne D, Cadorette JJ, Boody R, Gilmore MS. Staphylococcus aureus from ocular and otolaryngology infections are frequently resistant to clinically important antibiotics and are associated with lineages of community and hospital origins. PLoS One 2018;13(12):e0208518.Abstract
Staphylococcus aureus is an important human pathogen that causes serious antibiotic-resistant infections. Its population structure is marked by the appearance and dissemination of successful lineages across different settings. To begin understanding the population structure of S. aureus causing ocular and otolaryngology infections, we characterized 262 isolates by antimicrobial sensitivity testing and multilocus sequence typing (MLST). Methicillin-resistant S. aureus were subjected to SCCmec typing and Panton-Valentine leukocidin (PVL) screening. Although we detected a high level of genetic diversity among methicillin-sensitive (MSSA) isolates, (63 sequence types-STs), the population was dominated by five lineages: ST30, ST5, ST8, ST15 and ST97. Resistance to penicillin, erythromycin and clindamycin was common among the major MSSA lineages, with fluctuations markedly impacted by genetic background. Isolates belonging to the predominant lineage, ST30, displayed high rates of resistance to penicillin (100%), erythromycin (71%), and clindamycin (63%). Overall, 21% of the isolates were methicillin-resistant (MRSA), with an apparent enrichment among otitis and orbital cellulitis isolates (>40%). MRSA isolates belonged to 14 STs grouped in 5 clonal complexes (CC), however, CC5 (56.1%) and CC8 (38.6%) dominated the population. Most CC5 strains were SCCmec type II, and resembled the hospital-adapted USA100 clone. CC8 strains were SCCmec type IV, and 86% were positive for the PVL toxin, common features of the community-acquired clone USA300. CC5 strains harboring a SCCmec type IV, typical for the USA800 clone, comprised 15.5% of the population. USA100 strains were highly resistant to clindamycin, erythromycin and levofloxacin (100%), while USA300 strains were frequently resistant to erythromycin (89%) but displayed lower rates of resistance to levofloxacin (39%) and clindamycin (17%). Our data demonstrate that the ocular and otolaryngology S. aureus populations are composed of strains that are commonly resistant to clinically relevant antibiotics, and are associated with the major epidemic clonal complexes of both community and hospital origins.
Duarte MJ, Kozin ED, Bispo PJM, Mitchell AH, Gilmore MS, Remenschneider AK. Methicillin-resistant Staphylococcus aureus in acute otitis externa. World J Otorhinolaryngol Head Neck Surg 2018;4(4):246-252.Abstract
Objective: Otologic methicillin-resistant (MRSA) infection has historically been rare, but given the rise in community-acquired MRSA carriage and infection at other body sites, prevalence rates may be changing. The goal of this study was to determine the prevalence of MRSA in recent otologic cultures from patients with acute otitis externa (AOE). Study design: Retrospective review of an institutional microbiologic database. Methods: A retrospective analysis was performed on serial culture isolates taken from the ear at a quaternary care hospital from January 2014 to April 2016. The causative pathogen and antibiotic sensitivity was determined by culture isolation and end point mean inhibitory concentration (MIC) testing. Medical records were reviewed to document patient characteristics, chronicity of infection, symptomatology, and previous treatments. Results: Over the study period, 173 patients were diagnosed with AOE and underwent otologic cultures of the ear. Fifty-three (30.6%) of cultures grew (SA). Of SA infections, 15 (28.3%) were identified as MRSA. MRSA patients were typically older than patients with methicillin-sensitive SA (MSSA) (mean age 46.7 ± 17.9 29 ± 19.4,  = 0.003) and had more medical comorbidities (4 1.7,  = 0.001). Compared to patients with MSSA, patients with MRSA were significantly more likely to have had prior ototopical antibiotic exposure (37% 73%,  = 0.019). Conclusion: Contemporary ear culture isolates at quaternary care center show higher rates of MRSA compared to historical reports in the literature. Clinicians should consider ear cultures to identify MRSA AOE. Level of Evidence: IV.
Storey PP, Tauqeer Z, Yonekawa Y, Todorich B, Wolfe JD, Shah SP, Shah AR, Koto T, Abbey AM, Morizane Y, Sharma P, Wood EH, Morizane-Hosokawa M, Pendri P, Pancholy M, Harkey S, Jeng-Miller KW, Obeid A, Borkar DS, Chen E, Williams P, Okada AA, Inoue M, Shiraga F, Hirakata A, Shah CP, Prenner J, Garg S, Garg S, Garg S. The Impact of Prefilled Syringes on Endophthalmitis following Intravitreal Injection of Ranibizumab. Am J Ophthalmol 2018;Abstract
PURPOSE: To compare the rates of infectious endophthalmitis following intravitreal injection of ranibizumab using prefilled syringes vs. conventional preparation. DESIGN: Multicenter, retrospective, cohort study METHODS: All eyes receiving intravitreal injection of 0.5 mg ranibizumab for retinal vascular diseases at ten retina practices across the United States (2016 to 2017) and Japan (2009 to 2017) were included. The total number of eyes and injections were determined from billing codes. Endophthalmitis cases were determined from billing records and evaluated with chart review. Primary outcome was the rate of post-injection acute endophthalmitis. Secondary outcomes were visual acuity and microbial spectrum. RESULTS: A total of 243,754 intravitreal 0.5 mg ranibizumab injections (165,347 conventional and 78,407 prefilled) were administered to 43,132 unique patients during the study period. In the conventional ranibizumab group, a total of 43 cases of suspected endophthalmitis occurred (0.026%; 1 in 3,845 injections) and 22 cases of culture-positive endophthalmitis occurred (0.013%; 1 in 7,516 injections). In the prefilled ranibizumab group, 12 cases of suspected endophthalmitis occurred (0.015%; 1 in 6,534 injections) and 2 cases of culture-positive endophthalmitis occurred (0.0026%; 1 in 39,204 injections). Prefilled syringes were associated with a trend towards decreased risk of suspected endophthalmitis (odds ratio 0.59; 95% confidence interval 0.31 - 1.12; p=0.10) and a statistically significant decreased risk of culture-positive endophthalmitis (odds ratio 0.19; 95% confidence interval 0.045 - 0.82; p=0.025). Average logMAR vision loss at final follow-up was significantly worse for eyes that developed endophthalmitis from the conventional ranibizumab preparation compared to the prefilled syringe group (4.45 lines lost from baseline acuity vs. 0.38 lines lost; p=0.0062). Oral-associated flora was found in 27.3% (6/22) of conventional ranibizumab culture-positive endophthalmitis cases (3 cases of Streptococcus viridans, 3 cases of Enterococcus faecalis) compared to 0 cases in the prefilled ranibizumab group. CONCLUSION: In a large, multicenter, retrospective study the use of prefilled syringes during intravitreal injection of ranibizumab was associated with a reduced rate of culture-positive endophthalmitis, including from oral flora, as well as with improved visual acuity outcomes.
Zhai H, Bispo PJM, Kobashi H, Jacobs DS, Gilmore MS, Ciolino JB. Resolution of fluoroquinolone-resistant keratitis with a PROSE device for enhanced targeted antibiotic delivery. Am J Ophthalmol Case Rep 2018;12:73-75.Abstract
Purpose: To report the resolution of a fluoroquinolone-resistant keratitis with use of a prosthetic replacement of the ocular surface ecosystem (PROSE) device for enhanced targeted delivery of moxifloxiacin. Observations: A 62-year-old female presented with a 3-day history of pain, photophobia, and declining vision in left eye. The patient had a 2-year history of binocular PROSE treatment for ocular chronic graft-vs-host disease (cGVHD). A corneal ulcer was diagnosed and treated with topical 0.5% moxifloxacin solution 6 times per day, with continued wear of the PROSE device. After 4 days, worsening symptoms led to an increase in application of moxifloxicin to every 2 hours while awake. The drug was administered by removal of the device, cleaning and replenishing the reservoir with sterile saline, and adding one drop of the drug to the reservoir prior to reinsertion. Four days later, the corneal surface was epithelialized with only small subepithelial infiltrate remaining. The corneal culture grew an isolate carrying multiple mutations in the topoisomerase genes. These mutations were correlated with varying levels of resistance to ciprofloxacin (256 μg/mL), levofloxacin (8 μg/mL), and moxifloxacin (16 μg/mL). Conclusions and Importance: Although the infecting strain exhibited resistance to fluoroquinolones, the infection resolved when moxifloxacin was combined with PROSE therapy. Frequent dosing to the PROSE reservoir is likely to increase fluoroquinolone bioavailability and may represent a valuable approach to overcome antibiotic resistance.
Pan H, Yan Y, Zhang J, Zhao S, Feng L, Ou J, Cao N, Li M, Zhao W, Wan C, Ismail AM, Rajaiya J, Chodosh J, Zhang Q. Rapid Construction of a Replication-Competent Infectious Clone of Human Adenovirus Type 14 by Gibson Assembly. Viruses 2018;10(10)Abstract
In 1955, Human adenovirus type 14 (HAdV-B14p) was firstly identified in a military trainee diagnosed as acute respiratory disease (ARD) in the Netherlands. Fifty years later, a genomic variant, HAdV-B14p1, re-emerged in the U.S. and caused large and fatal ARD outbreaks. Subsequently, more and more ARD outbreaks occurred in Canada, the UK, Ireland, and China, in both military and civil settings. To generate a tool for the efficient characterization of this new genomic variant, a full-length infectious genomic clone of HAdV-B14 was successfully constructed using one-step Gibson Assembly method in this study. Firstly, the full genome of HAdV-B14p1 strain GZ01, the first HAdV-B14 isolate in China, was assembled into pBR322 plasmid by Gibson Assembly. The pBRAdV14 plasmid, generated by Gibson Assembly, was analyzed and verified by PCR, restriction enzymes digestion and the sequencing. Secondly, viruses were rescued from pBRAdV14-transfected A549 cells. The integrity of the rescued viruses was identified by restriction enzyme analysis. The complete sequence of the infectious clone was further sequenced. No mutation was found in the infectious clone during the construction when compared with the parental virus and pBR322 sequences. The direct immunofluorescence assay indicated the expression of the hexon protein. Finally, typical virions were observed; the one-step growth curves further showed that the DNA replication and viral reproduction efficiency of pBRAd14 derived viruses was similar with that of wild-type HAdV-B14 strain. The successful construction of the replication-competent infectious clone of pBRAdV14 facilitates the development of vaccine and antiviral drugs against HAdV-B14, as well as provides a novel strategy for rapid construction of infectious viral clones for other large-genome DNA viruses.
Kempen JH, Tekle-Haimanot R, Hunduma L, Alemayehu M, Pistilli M, Abashawl A, Lawrence SD, Alemayehu W. Fluorometholone 0.1% as Ancillary Therapy for Trachomatous Trichiasis Surgery: Randomized Clinical Trial. Am J Ophthalmol 2018;Abstract
PURPOSE: To assess the hypothesis that fluorometholone 0.1% eye drops are safe and effective as adjunctive therapy for trachomatous trichiasis (TT) surgery; determining the most promising dose. DESIGN: Randomized, placebo-controlled, double-masked parallel dose-ranging clinical trial. METHODS: Patients undergoing upper lid TT surgery at a rural Ethiopian hospital were randomized to fluorometholone 0.1% twice daily for four weeks, four times daily for four weeks, four times daily for eight weeks, or matching frequency placebo in a 3:1:3:1:3:1 ratio for one eye. Randomization was stratified by TT severity (1-4 vs. ≥5 lashes touching the globe). Safety outcomes (intraocular pressure [IOP] elevation, cataract, and other dose-limiting toxicities) and post-operative TT incidence were assessed over one year. RESULTS: Subjects randomized were 39:13:39:13:38:13 in the respective groups, and one subject in the eight weeks' fluorometholone group was withdrawn. 148/154 subjects (96.1%) completed one year's follow-up. Among eyes receiving fluorometholone four times daily, 1/76 developed IOP elevation≥30 mmHg (to 37 mmHg), and one had an allergic reaction attributed to the study drug; each resolved upon drug cessation without sequelae. No cataract or other dose-limiting toxicity events occurred. Post-operative TT within one year occurred in 29.3% of placebo eyes vs. 17.7%, 19.6% and 23.2% amongst the respective fluorometholone groups (p=0.29 comparing placebo vs. all active treatments combined). CONCLUSIONS: The results suggest fluorometholone 0.1% is likely to be safe and efficacious to reduce post-op TT following TT surgery, and one drop twice daily for four weeks is the most promising dose. Confirmation in a full-scale clinical trial is needed before programmatic implementation.
Lieberman MT, Van Tyne D, Dzink-Fox JA, Ma EJ, Gilmore MS, Fox JG. Long-Term Colonization Dynamics of Enterococcus faecalis in Implanted Devices in Research Macaques. Appl Environ Microbiol 2018;84(18)Abstract
is a common opportunistic pathogen that colonizes cephalic recording chambers (CRCs) of macaques used in cognitive neuroscience research. We previously characterized 15 strains isolated from macaques at the Massachusetts Institute of Technology (MIT) in 2011. The goal of this study was to examine how a 2014 protocol change prohibiting the use of antimicrobials within CRCs affected colonizing strains. We collected 20 isolates from 10 macaques between 2013 and 2017 for comparison to 4 isolates previously characterized in 2011 with respect to the sequence type (ST) distribution, antimicrobial resistance, biofilm formation, and changes in genes that might confer a survival advantage. ST4 and ST55 were predominant among the isolates characterized in 2011, whereas the less antimicrobial-resistant lineage ST48 emerged to dominance after 2013. Two macaques remained colonized by ST4 and ST55 strains for 5 and 4 years, respectively. While the antimicrobial resistance and virulence factors identified in these ST4 and ST55 strains remained relatively stable, we detected an increase in biofilm formation ability over time in both isolates. We also found that ST48 strains were typically robust biofilm formers, which could explain why this ST increased in prevalence. Finally, we identified mutations in the DNA mismatch repair genes and in separate ST55 and ST4 strains and confirmed that strains bearing these mutations displayed a hypermutator phenotype. The presence of a hypermutator phenotype may complicate future antimicrobial treatment for clinically relevant infections in macaques. is a common cause of health care-associated infections in humans, largely due to its ability to persist in the hospital environment, colonize patients, acquire antimicrobial resistance, and form biofilms. Understanding how enterococci evolve in health care settings provides insight into factors affecting enterococcal survival and persistence. Macaques used in neuroscience research have long-term cranial implants that, despite best practices, often become colonized by This provides a unique opportunity to noninvasively examine the evolution of enterococci on a long-term indwelling device. We collected strains from cephalic implants over a 7-year period and characterized the sequence type, antimicrobial resistance, virulence factors, biofilm production, and hypermutator phenotypes. Improved antimicrobial stewardship allowed a less-antimicrobial-resistant strain to predominate at the implant interface, potentially improving antimicrobial treatment outcomes if future clinical infections occur. Biofilm formation appears to play an important role in the persistence of the strains associated with these implants.
Dabul ANG, Avaca-Crusca JS, Van Tyne D, Gilmore MS, Camargo ILBC. Resistance in In Vitro Selected Tigecycline-Resistant Methicillin-Resistant Staphylococcus aureus Sequence Type 5 Is Driven by Mutations in mepR and mepA Genes. Microb Drug Resist 2018;24(5):519-526.Abstract
A tigecycline-susceptible (TGC-S) Sequence Type (ST) 5 clinical methicillin-resistant Staphylococcus aureus (MRSA) strain was cultured in escalating levels of tigecycline, yielding mutants eightfold more resistant. Their genomes were sequenced to identify genetic alterations, resulting in resistance. Alterations in rpsJ, commonly related to tigecycline resistance, were also investigated. Tigecycline resistance was mediated by loss-of-function mutations in the transcriptional repressor mepR, resulting in derepression of the efflux pump mepA. Increased levels of resistance were obtained by successive mutations in mepA itself. No alterations in RpsJ were observed in selected strains, but we observed a K57M substitution, previously correlated with resistance, among TGC-S clinical strains. Thus, the pathway to tigecycline resistance in CC5 MRSA in vitro appears to be derepression of mep operon as the result of mepR loss-of-function mutation, followed by alterations in MepA efflux pump. This shows that other evolutionary pathways, besides mutation of rpsJ, are available for evolving tigecycline resistance in CC5 MRSA.
Chen L, Fu T, Gu H, Jie Y, Sun Z, Jiang D, Yu J, Zhu X, Xu J, Hong J. Trends in dacryocystitis in China: A STROBE-compliant article. Medicine (Baltimore) 2018;97(26):e11318.Abstract
The aim of the study was to review the distribution, current trends, and microbiological characteristics of bacterial pathogens isolated from dacryocystitis patients in China during the last 15 years.This is a retrospective multiple-center noncomparative case series. The medical records of 15,452 consecutive patients from 7 cities diagnosed as having dacryocystitis between 2002 and 2016 were reviewed. The patients' demographics, microbiological data, and antibiotic sensitivity were reviewed and analyzed.A total of 3344 lacrimal sac content cultures were taken (21.6%) during the study period. A pathogen was identified in 1996 samples (59.7%), with bacterial isolates accounting for 1902 of the positive cultures (95.3%). Gram-positive isolates, gram-negative isolates, and anaerobic bacteria were found in 1218 (61.0%), 607 (30.4%), and 285 (14.3%) samples, respectively. An increase in gram-positive isolates over the study duration was found (P = .003). The predominant isolates were coagulase negative Staphylococci (485, 25.5%), Staphylococcus aureus (186, 9.8%), Pseudomonas aeruginosa (184, 9.7%), and Haemophilus influenzae (152, 9.0%). There was a trend toward increasing resistance to erythromycin from 10.5% during the first 5 years of the study to 20.7% during the last 5 years (P < .001). Antimicrobial susceptibility testing showed that gatifloxacin was the most effective drug against most of gram-positive, gram-negative, and anaerobic bacteria.The microbial culture rate of dacryocystitis in China is low. There was an increase in the percentage of gram-positive bacteria over time. The sensitivity of gram-positive isolates to tested antibiotics is relatively low compared with that of gram-negative isolates. Our data show that the empiric use of fourth-generation fluoroquinolones in refractory dacryocystitis may be justified.
Lee JY, Lee JS, Materne EC, Rajala R, Ismail AM, Seto D, Dyer DW, Rajaiya J, Chodosh J. Bacterial RecA Protein Promotes Adenoviral Recombination during Infection. mSphere 2018;3(3)Abstract
Adenovirus infections in humans are common and sometimes lethal. Adenovirus-derived vectors are also commonly chosen for gene therapy in human clinical trials. We have shown in previous work that homologous recombination between adenoviral genomes of human adenovirus species D (HAdV-D), the largest and fastest growing HAdV species, is responsible for the rapid evolution of this species. Because adenovirus infection initiates in mucosal epithelia, particularly at the gastrointestinal, respiratory, genitourinary, and ocular surfaces, we sought to determine a possible role for mucosal microbiota in adenovirus genome diversity. By analysis of known recombination hot spots across 38 human adenovirus genomes in species D (HAdV-D), we identified nucleotide sequence motifs similar to bacterial Chi sequences, which facilitate homologous recombination in the presence of bacterial Rec enzymes. These motifs, referred to here as Chi, were identified immediately 5' to the sequence encoding penton base hypervariable loop 2, which expresses the arginine-glycine-aspartate moiety critical to adenoviral cellular entry. Coinfection with two HAdV-Ds in the presence of an lysate increased recombination; this was blocked in a RecA mutant strain, DH5α, or upon RecA depletion. Recombination increased in the presence of lysate despite a general reduction in viral replication. RecA colocalized with viral DNA in HAdV-D-infected cell nuclei and was shown to bind specifically to Chi sequences. These results indicate that adenoviruses may repurpose bacterial recombination machinery, a sharing of evolutionary mechanisms across a diverse microbiota, and unique example of viral commensalism. Adenoviruses are common human mucosal pathogens of the gastrointestinal, respiratory, and genitourinary tracts and ocular surface. Here, we report finding Chi-like sequences in adenovirus recombination hot spots. Adenovirus coinfection in the presence of bacterial RecA protein facilitated homologous recombination between viruses. Genetic recombination led to evolution of an important external feature on the adenoviral capsid, namely, the penton base protein hypervariable loop 2, which contains the arginine-glycine-aspartic acid motif critical to viral internalization. We speculate that free Rec proteins present in gastrointestinal secretions upon bacterial cell death facilitate the evolution of human adenoviruses through homologous recombination, an example of viral commensalism and the complexity of virus-host interactions, including regional microbiota.
Sié A, Diarra A, Millogo O, Zongo A, Lebas E, Bärnighausen T, Chodosh J, Porco TC, Deiner MS, Lietman TM, Keenan JD, Oldenburg CE. Seasonal and Temporal Trends in Childhood Conjunctivitis in Burkina Faso. Am J Trop Med Hyg 2018;Abstract
Acute conjunctivitis follows a seasonal pattern. Although its clinical course is typically self-limited, conjunctivitis epidemics incur a substantial economic burden because of missed school and work days. This study investigated seasonal and temporal trends of childhood conjunctivitis in the entire country of Burkina Faso from 2013 to 2016, using routine monthly surveillance from 2,444 government health facilities. A total of 783,314 cases were reported over the 4-year period. Conjunctivitis followed a seasonal pattern throughout the country, with a peak in April. A nationwide conjunctivitis outbreak with a peak in September 2016 was noted ( < 0.001), with an excess number of cases first detected in June 2016. Nationwide passive surveillance was able to detect an epidemic 3 months before its peak, which may aide in allocation of resources for containment and mitigation of transmission in future outbreaks.
Johnston T, Van Tyne D, Chen RF, Fawzi NL, Kwon B, Kelso MJ, Gilmore MS, Mylonakis E. Propyl-5-hydroxy-3-methyl-1-phenyl-1H-pyrazole-4-carbodithioate (HMPC): a new bacteriostatic agent against methicillin-resistant Staphylococcus aureus. Sci Rep 2018;8(1):7062.Abstract
The emergence of Staphylococcus aureus strains resistant to 'last resort' antibiotics compels the development of new antimicrobials against this important human pathogen. We found that propyl 5-hydroxy-3-methyl-1-phenyl-1H-pyrazole-4-carbodithioate (HMPC) shows bacteriostatic activity against S. aureus (MIC = 4 μg/ml) and rescues Caenorhabditis elegans from S. aureus infection. Whole-genome sequencing of S. aureus mutants resistant to the compound, along with screening of a S. aureus promoter-lux reporter array, were used to explore possible mechanisms of action. All mutants resistant to HMPC acquired missense mutations at distinct codon positions in the global transcriptional regulator mgrA, followed by secondary mutations in the phosphatidylglycerol lysyltransferase fmtC/mprF. The S. aureus promoter-lux array treated with HMPC displayed a luminescence profile that was unique but showed similarity to DNA-damaging agents and/or DNA replication inhibitors. Overall, HMPC is a new anti-staphylococcal compound that appears to act via an unknown mechanism linked to the global transcriptional regulator MgrA.