First report of KPC variants conferring ceftazidime-avibactam resistance in Colombia: introducing KPC-197.

Resistance to ceftazidime-avibactam (CZA) due to Klebsiella pneumoniae carbapenemase (KPC) variants is increasing worldwide. We characterized two CZA-resistant clinical Klebsiella pneumoniae strains by antimicrobial susceptibility test, conjugation assays, and WGS. Isolates belonged to ST258 and ST45, and produced a KPC-31 and a novel variant KPC-197, respectively. The novel KPC variant presents a deletion of two amino acids on the Ω-loop (del_168-169_EL) and an insertion of two amino acids in position 274 (Ins_274_DS). Continued surveillance of KPC variants conferring CZA resistance in Colombia is warranted. IMPORTANCE: Latin America and the Caribbean is an endemic region for carbapenemases. Increasingly high rates of Klebsiella pneumoniae carbapenemase (KPC) have established ceftazidime-avibactam (CZA) as an essential antimicrobial for the treatment of infections due to MDR Gram-negative pathogens. Although other countries in the region have reported the emergence of CZA-resistant KPC variants, this is the first description of such enzymes in Colombia. This finding warrants active surveillance, as dissemination of these variants could have devastating public health consequences.

Actualización sobre la resistencia antimicrobiana en instituciones de salud de nivel III y IV en Colombia entre enero del 2018 y diciembre del 2021

Introducción. El comportamiento de la resistencia antimicrobiana es fundamental en el mejoramiento y ajuste de los programas de optimización de uso de antimicrobianos, la implementación de las guías terapéuticas y las precauciones que limitan la transmisión cruzada de bacterias resistentes entre pacientes. Desde el inicio del 2020, la pandemia del SARS-CoV-2 desafió profundamente al sistema de salud y, según algunos reportes, aumentó las tasas de resistencia antimicrobiana. Objetivo. Describir el comportamiento de la resistencia antimicrobiana en los microrganismos más frecuentes en veinte hospitales colombianos durante el periodo 2018-2021. Materiales y métodos. Se trata de un estudio descriptivo basado en la información microbiológica reportada por veinte instituciones de salud de nivel III y IV, entre enero de 2018 y diciembre de 2021, en doce ciudades de Colombia, las cuales hacen parte del "Grupo para el estudio de la resistencia nosocomial en Colombia", liderado por la Universidad El Bosque. La identificación de género y especie de los microorganismos más frecuentes, junto con su perfil de resistencia frente a antibióticos marcadores, se determinaron mediante el análisis de los datos vía WHONET. Resultados. En general, los 10 microorganismos más frecuentes analizados a lo largo de los 4 años no presentaron cambios estadísticamente significativos en sus perfiles de resistencia durante los cuatro años del periodo evaluado, de 2018 a 2021. En contraste, Pseudomonas aeruginosa aumentó su resistencia frente a piperacilinatazobactam y carbapenémicos, lo cual fue estadísticamente significativo. Conclusiones. Los cambios en la resistencia antimicrobiana en estos años no han sido estadísticamente significativos, excepto para P. aeruginosa, bacteria que mostró un incremento en las tasas de resistencia a piperacilina-tazobactam y carbapenémicos.

Introduction. Antimicrobial resistance surveillance is a fundamental tool for the development, improvement, and adjustment of antimicrobial stewardship programs, therapeutic guidelines, and universal precautions to limit the cross-transmission of resistant bacteria between patients. Since the beginning of 2020, the SARS-CoV-2 pandemic profoundly challenged the health system and, according to some reports, increased the rates of antimicrobial resistance. Objective. To describe the behavior of antimicrobial resistance of the most frequent bacterial pathogens in twenty Colombian hospitals from January 2018 to December 2021. Materials and methods. We conducted a descriptive study based on the microbiological information recorded from January 2018 to December 2021 in twenty levels III and IV health institutions in twelve Colombian cities. We identified the species of the ten most frequent bacteria along with their resistance profile to the antibiotic markers after analyzing the data through WHONET. Results. We found no statistically significant changes in most pathogens' resistance profiles from January 2018 to December 2021. Only Pseudomonas aeruginosa had a statistically significant increase in its resistance profile, particularly to piperacillin/ tazobactam and carbapenems. Conclusions. The changes in antimicrobial resistance in these four years were not statistically significant except for P. aeruginosa to piperacillin/tazobactam and carbapenems.

Update of antimicrobial resistance in level III and IV health institutions in Colombia between January 2018 and December 2021 / Actualización sobre la resistencia antimicrobiana en instituciones de salud de nivel III y IV en Colombia entre enero del 2018 y diciembre del 2021

Introduction: Antimicrobial resistance surveillance is a fundamental tool for the development, improvement, and adjustment of antimicrobial stewardship programs, therapeutic guidelines, and universal precautions to limit the cross-transmission of resistant bacteria between patients. Since the beginning of 2020, the SARS-CoV-2 pandemic profoundly challenged the health system and, according to some reports, increased the rates of antimicrobial resistance. Objective: To describe the behavior of antimicrobial resistance of the most frequent bacterial pathogens in twenty Colombian hospitals from January 2018 to December 2021. Materials and methods: We conducted a descriptive study based on the microbiological information recorded from January 2018 to December 2021 in twenty levels III and IV health institutions in twelve Colombian cities. We identified the species of the ten most frequent bacteria along with their resistance profile to the antibiotic markers after analyzing the data through WHONET. Results: We found no statistically significant changes in most pathogens' resistance profiles from January 2018 to December 2021. Only Pseudomonas aeruginosa had a statistically significant increase in its resistance profile, particularly to piperacillin/tazobactam and carbapenems. Conclusions: The changes in antimicrobial resistance in these four years were not statistically significant except for P. aeruginosa to piperacillin/tazobactam and carbapenems.

Introducción: El comportamiento de la resistencia antimicrobiana es fundamental en el mejoramiento y ajuste de los programas de optimización de uso de antimicrobianos, la implementación de las guías terapéuticas y las precauciones que limitan la transmisión cruzada de bacterias resistentes entre pacientes. Desde el inicio del 2020, la pandemia del SARS-CoV-2 desafió profundamente al sistema de salud y, según algunos reportes, aumentó las tasas de resistencia antimicrobiana. OBJETIVO: Describir el comportamiento de la resistencia antimicrobiana en los microrganismos más frecuentes en veinte hospitales colombianos durante el periodo 2018-2021. Materiales y métodos: Se trata de un estudio descriptivo basado en la información microbiológica reportada por veinte instituciones de salud de nivel III y IV, entre enero de 2018 y diciembre de 2021, en doce ciudades de Colombia, las cuales hacen parte del "Grupo para el estudio de la resistencia nosocomial en Colombia", liderado por la Universidad El Bosque. La identificación de género y especie de los microorganismos más frecuentes, junto con su perfil de resistencia frente a antibióticos marcadores, se determinaron mediante el análisis de los datos vía WHONET. RESULTADOS: En general, los 10 microorganismos más frecuentes analizados a lo largo de los 4 años no presentaron cambios estadísticamente significativos en sus perfiles de resistencia durante los cuatro años del periodo evaluado, de 2018 a 2021. En contraste, Pseudomonas aeruginosa aumentó su resistencia frente a piperacilina-tazobactam y carbapenémicos, lo cual fue estadísticamente significativo. CONCLUSIONES: Los cambios en la resistencia antimicrobiana en estos años no han sido estadísticamente significativos, excepto para P. aeruginosa, bacteria que mostró un incremento en las tasas de resistencia a piperacilina-tazobactam y carbapenémicos.

Antimicrobial Stewardship Programs in Latin America and the Caribbean: A Story of Perseverance, Challenges, and Goals.

Antimicrobial resistance is one of the major global health threats. Antimicrobial stewardship (AMS) has been set as a priority within international action plans to combat this issue. The region of Latin America and the Caribbean are recognized for their high antimicrobial resistance rates; nevertheless, a low number of studies describing implemented interventions for this topic have been published. This review aims to provide an overview of the status of AMS in our region, focusing on the main progress achieved and describing the different published efforts made by countries towards the implementation of antimicrobial stewardship programs (ASP). Common areas of intervention included were (a) education approaches, (b) antimicrobial guideline implementation and monitoring, (c) diagnostic stewardship, (d) technological tools: electronic clinical decision support systems in AMS, (e) pharmacy-driven protocols and collaborative practice agreements, and (f) economic impact. The search demonstrated the varied interventions implemented in diverse healthcare settings; the results accentuate their influence on antimicrobial consumption, antimicrobial resistance, clinical outcomes, and direct economic impact. The integration of multiple strategies within each hospital was highlighted as an essential key to ASP success. Even though the literature found demonstrated clear progress, there is still a special need for strengthening leadership from the top down, defining goals based on needs, and gaining support through policy and financing in LAC.

Antimicrobial stewardship programs in seven Latin American countries: facing the challenges.

BACKGROUND: Studies have shown that more than 50% of the antibiotics used in hospitals are unnecessary or inappropriate and, that antimicrobial resistance may cost up to 20 billion USD in excess medical costs each year. On the other hand, Antimicrobial Stewardship Programs (ASP) significantly reduce inappropriate antimicrobial use, emergence of antimicrobial resistance, healthcare associated infections, and costs in hospital settings. OBJECTIVE: To evaluate the development of ASP and antibiotic savings in 7 Latin American hospitals using standardized quantitative indicators in all the participating health care institutions. METHODS: An interventional study was conducted, where pre- and post- evaluations were performed using a standardized score tool adapted from the Joint Commission International accreditation standards and, the Colombian Institute of Technical Standards and Certification. We evaluated ASP from 7 Latin American hospitals between 2019 and 2020. A pre-intervention evaluation was done in each hospital to quantify the degree of development of the ASP (ASP Development score). Based on these results, tailored on-site training was implemented in each hospital, followed by a post-intervention evaluation to quantify improvement of ASP-development indicators. In addition, monetary savings in antimicrobials derived from the ASP intervention were estimated. RESULTS: In the pre-intervention evaluation, the average ASP development score for the 7 institutions was 65.8% (40-94.3%). The items with the lowest development score were those related to monitoring and communicating the ASP progress and success. For the post-intervention evaluation, 2 institutions couldn't participate due to the pressure imposed by the COVID-19 pandemic. For the remaining 5/7 hospitals, the average ASP development score was 82.3% with an increase of 12.0% when compared to the pre-intervention measurement of the same institutions (average pre-intervention score 70.3% (48.2%-94.3%) The items with a significant increase were key performance indicators, AMS education and training of the prescribers. Three of the seven (3/7) hospitals reported antibiotic monetary savings associated to the ASP intervention. CONCLUSIONS: The use of the tool described shown to be useful to evaluate specific areas of ASP-development that were lacking and tailor interventions for the participating hospitals, consequently, it helped improve ASP-development in the institutions that underwent pre- intervention and post-intervention analysis. In addition, the strategies showed monetary savings on antimicrobial costs when measured.

Molecular Mechanisms of Resistance to Ceftazidime/Avibactam in Clinical Isolates of Enterobacterales and Pseudomonas aeruginosa in Latin American Hospitals.

Ceftazidime-avibactam (CZA) is the combination of a third-generation cephalosporin and a new non-ß-lactam ß-lactamase inhibitor capable of inactivating class A, C, and some D ß-lactamases. From a collection of 2,727 clinical isolates of Enterobacterales (n = 2,235) and P. aeruginosa (n = 492) that were collected between 2016 and 2017 from five Latin American countries, we investigated the molecular resistance mechanisms to CZA of 127 (18/2,235 [0.8%] Enterobacterales and 109/492 [22.1%] P. aeruginosa). First, by qPCR for the presence of genes encoding KPC, NDM, VIM, IMP, OXA-48-like, and SPM-1 carbapenemases, and second, by whole-genome sequencing (WGS). From the CZA-resistant isolates, MBL-encoding genes were detected in all 18 Enterobacterales and 42/109 P. aeruginosa isolates, explaining their resistant phenotype. Resistant isolates that yielded a negative qPCR result for any of the MBL encoding genes were subjected to WGS. The WGS analysis of the 67 remaining P. aeruginosa isolates showed mutations in genes previously associated with reduced susceptibility to CZA, such as those involved in the MexAB-OprM efflux pump and AmpC (PDC) hyperproduction, PoxB (blaOXA-50-like), FtsI (PBP3), DacB (PBP4), and OprD. The results presented here offer a snapshot of the molecular epidemiological landscape for CZA resistance before the introduction of this antibiotic into the Latin American market. Therefore, these results serve as a valuable comparison tool to trace the evolution of the resistance to CZA in this carbapenemase-endemic geographical region. IMPORTANCE In this manuscript, we determine the molecular mechanisms of ceftazidime-avibactam resistance in Enterobacterales and P. aeruginosa isolates from five Latin American countries. Our results reveal a low rate of resistance to ceftazidime-avibactam among Enterobacterales; in contrast, resistance in P. aeruginosa has proven to be more complex, as it might involve multiple known and possibly unknown resistance mechanisms.

Identification of mcr-1 Genes and Characterization of Resistance Mechanisms to Colistin in Escherichia coli Isolates from Colombian Hospitals.

We report the presence of the mcr-1 gene among 880 Escherichia coli clinical isolates collected in 13 hospitals from 12 Colombian cities between 2016 and 2019. Seven (0.8%) isolates were colistin resistant (MIC ≥ 4 µg/mL). These colistin-resistant isolates were screened for the presence of the mcr-1 gene; five carried the gene. These five isolates were subjected to whole genome sequencing (WGS) to identify additional resistomes and their ST. In addition, antimicrobial susceptibility testing revealed that all E. coli isolates carrying mcr-1 were susceptible to third generation-cephalosporin and carbapenems, except one, which carried an extended-spectrum ß-lactamase (CTX-M-55), along with the fosfomycin resistance encoding gene, fosA. WGS indicated that these isolates belonged to four distinct sequence types (ST58, ST46, ST393, and a newly described ST14315) and to phylogroups B1, A, and D. In this geographic region, the spread of mcr-1 in E. coli is low and has not been inserted into high-risk clones such as ST131, which has been present in the country longer.

Molecular mechanisms leading to ceftolozane/tazobactam resistance in clinical isolates of Pseudomonas aeruginosa from five Latin American countries.

Objectives: Identify molecular mechanisms responsible for the in vitro non-susceptibility to ceftolozane/tazobactam (TOL) in a group of 158 clinical isolates of Pseudomonas aeruginosa from five Latin American countries collected before the introduction of TOL into the clinical practice. Methods: Clinical isolates of P. aeruginosa (n = 504) were collected between January 2016 and October 2017 from 20 hospitals located in Argentina, Brazil, Chile, Colombia, and Mexico. Minimum inhibitory concentrations (MICs) to TOL were determined by standard broth microdilution and interpreted according to CLSI breakpoints. Initially, production of carbapenemases in TOL non-susceptible isolates was assessed by Rapidec® followed by qPCR to detect bla KPC, bla NDM-1, bla VIM, and bla IMP. Illumina® WGS was performed for isolates in which non-susceptibility to TOL was not mediated by carbapenemases. Results: A total of 158 (31.3%) isolates were non-susceptible to TOL. In 74 (46.8%) of these isolates, non-susceptibility to TOL was explained by the production of at least one carbapenemase. WGS revealed that some isolates carried ESBLs, mutated bla PDC and ampD, associated with decreased susceptibility to TOL. Conclusion: Substitutions found in PDC and carbapenemase production were the most common presumed mechanisms of resistance to TOL detected in this study. This study shows that epidemiological surveillance is warranted to monitor the emergence of novel mechanisms of resistance to TOL that might compromise its clinical utility.

Comparative In Vitro Activity of Ceftolozane/Tazobactam against Clinical Isolates of Pseudomonas aeruginosa and Enterobacterales from Five Latin American Countries.

BACKGROUND: Ceftolozane/tazobactam (C/T) is a combination of an antipseudomonal oxyiminoaminothiazolyl cephalosporin with potent in vitro activity against Pseudomonas aeruginosa and tazobactam, a known ß-lactamase inhibitor. The aim of this study was to evaluate the activity of C/T against clinical isolates of P. aeruginosa and Enterobacterales collected from five Latin American countries between 2016 and 2017, before its clinical use in Latin America, and to compare it with the activity of other available broad-spectrum antimicrobial agents. METHODS: a total of 2760 clinical isolates (508 P. aeruginosa and 2252 Enterobacterales) were consecutively collected from 20 hospitals and susceptibility to C/T and comparator agents was tested and interpreted following the current guidelines. RESULTS: according to the CLSI breakpoints, 68.1% (346/508) of P. aeruginosa and 83.9% (1889/2252) of Enterobacterales isolates were susceptible to C/T. Overall, C/T demonstrated higher in vitro activity than currently available cephalosporins, piperacillin/tazobactam and carbapenems when tested against P. aeruginosa, and its performance in vitro was comparable to fosfomycin. When tested against Enterobacterales, it showed higher activity than cephalosporins and piperacillin/tazobactam, and similar activity to ertapenem. CONCLUSIONS: these results show that C/T is an active ß-lactam agent against clinical isolates of P. aeruginosa and Enterobacterales.

Molecular Analysis of Polymyxin Resistance among Carbapenemase-Producing Klebsiella pneumoniae in Colombia.

Polymyxin resistance in Klebsiella pneumoniae has been attributed to mutations in mgrB, phoPQ, pmrAB, and crrAB and to the presence of mcr plasmid-mediated genes. Herein, we describe the molecular characteristics of 24 polymyxin- and carbapenem-resistant K. pneumoniae isolates recovered from six Colombian cities between 2009 and 2019. Minimum inhibitory concentrations (MICs) to polymyxin were confirmed by broth microdilution, and whole-genome sequencing was performed to determine sequence type, resistome, and mutations in the genes related to polymyxin resistance, as well the presence of mcr. The results showed high-level resistance to polymyxin (MICs ≥ 4 µg/mL). blaKPC-3 was present in the majority of isolates (17/24; 71%), followed by blaKPC-2 (6/24; 25%) and blaNDM-1 (1/24; 4%). Most isolates belonged to the CG258 (17/24; 71%) and presented amino acid substitutions in PmrB (22/24; 92%) and CrrB (15/24; 63%); mutations in mgrB occurred in only five isolates (21%). Additional mutations in pmrA, crrA, and phoPQ nor any of the mcr resistance genes were identified. In conclusion, we found clonal dissemination of polymyxin and carbapenem-resistant K. pneumoniae isolates in Colombia, mainly associated with CG258 and blaKPC-3. Surveillance of this multidrug-resistant clone is warranted due to the limited therapeutic options for the treatment of carbapenem-resistant K. pneumoniae infections.

Update on the epidemiology of carbapenemases in Latin America and the Caribbean.

INTRODUCTION: Carbapenemases are ß-lactamases able to hydrolyze a wide range of ß-lactam antibiotics, including carbapenems. Carbapenemase production in Enterobacterales, Pseudomonas aeruginosa, and Acinetobacter spp., with and without the co-expression of other ß-lactamases is a serious public health threat. Carbapenemases belong to three main classes according to the Ambler classification: class A, class B, and class D. AREAS COVERED: Carbapenemase-bearing pathogens are endemic in Latin America. In this review, we update the status of carbapenemases in Latin America and the Caribbean. EXPERT OPINION: Understanding the current epidemiology of carbapenemases in Latin America and the Caribbean is of critical importance to improve infection control policies limiting the dissemination of multi-drug-resistant pathogens and in implementing appropriate antimicrobial therapy.

Genomic Analysis of CTX-M-Group-1-Producing Extraintestinal Pathogenic E. coli (ExPEc) from Patients with Urinary Tract Infections (UTI) from Colombia.

BACKGROUND: The dissemination of the uropathogenic O25b-ST131 Escherichia coli clone constitutes a threat to public health. We aimed to determine the circulation of E. coli strains belonging to O25b:H4-B2-ST131 and the H30-Rx epidemic subclone causing hospital and community-acquired urinary tract infections (UTI) in Colombia. METHODS: Twenty-six nonduplicate, CTX-M group-1-producing isolates causing UTI in the hospital and community were selected for this study. RESULTS: Twenty-two E. coli isolates harboring CTX-M-15, one CTX-M-3, and three CTX-M-55 were identified. Multilocus Sequence Typing (MLST) showed a variety of sequence types (STs), among which, ST131, ST405, and ST648 were reported as epidemic clones. All the E. coli ST131 sequences carried CTX-M-15, from which 80% belonged to the O25b:H4-B2 and H30-Rx pandemic subclones and were associated with virulence factors iss, iha, and sat. E. coli isolates (23/26) were resistant to ciprofloxacin and associated with amino acid substitutions in quinolone resistance-determining regions (QRDR). We detected two carbapenem-resistant E. coli isolates, one coproducing CTX-M-15, KPC-2, and NDM-1 while the other presented mutations in ompC. Additionally, one isolate harbored the gene mcr-1. CONCLUSIONS: Our study revealed the circulation of the E. coli ST131, O25b:H4-B2-H30-Rx subclone, harboring CTX-M-15, QRDR mutations, and other resistant genes. The association of the H30-Rx subclone with sepsis and rapid dissemination warrants attention from the public health and infections control.

Cell Heterogeneity in Staphylococcal Communities.

The human pathogen Staphylococcus aureus is a gram-positive bacterium that causes difficult-to-treat infections. One of the reasons why S. aureus is such as successful pathogen is due to the cell-to-cell physiological variability that exists within microbial communities. Many laboratories around the world study the genetic mechanisms involved in S. aureus cell heterogeneity to better understand infection mechanism of this bacterium. It was recently shown that the Agr quorum-sensing system, which antagonistically regulates biofilm-associated or acute bacteremia infections, is expressed in a subpopulation of specialized cells. In this review, we discuss the different genetic mechanism for bacterial cell differentiation and the physiological properties of the distinct cell types that are already described in S. aureus communities, as well as the role that these cell types play during an infection process.

Cell differentiation defines acute and chronic infection cell types in Staphylococcus aureus.

A central question to biology is how pathogenic bacteria initiate acute or chronic infections. Here we describe a genetic program for cell-fate decision in the opportunistic human pathogen Staphylococcus aureus, which generates the phenotypic bifurcation of the cells into two genetically identical but different cell types during the course of an infection. Whereas one cell type promotes the formation of biofilms that contribute to chronic infections, the second type is planktonic and produces the toxins that contribute to acute bacteremia. We identified a bimodal switch in the agr quorum sensing system that antagonistically regulates the differentiation of these two physiologically distinct cell types. We found that extracellular signals affect the behavior of the agr bimodal switch and modify the size of the specialized subpopulations in specific colonization niches. For instance, magnesium-enriched colonization niches causes magnesium binding to S. aureusteichoic acids and increases bacterial cell wall rigidity. This signal triggers a genetic program that ultimately downregulates the agr bimodal switch. Colonization niches with different magnesium concentrations influence the bimodal system activity, which defines a distinct ratio between these subpopulations; this in turn leads to distinct infection outcomes in vitro and in an in vivo murine infection model. Cell differentiation generates physiological heterogeneity in clonal bacterial infections and helps to determine the distinct infection types.

Reconstruction of mreB expression in Staphylococcus aureus via a collection of new integrative plasmids.

Protein localization has been traditionally explored in unicellular organisms, whose ease of genetic manipulation facilitates molecular characterization. The two rod-shaped bacterial models Escherichia coli and Bacillus subtilis have been prominently used for this purpose and have displaced other bacteria whose challenges for genetic manipulation have complicated any study of cell biology. Among these bacteria is the spherical pathogenic bacterium Staphylococcus aureus. In this report, we present a new molecular toolbox that facilitates gene deletion in staphylococci in a 1-step recombination process and additional vectors that facilitate the insertion of diverse reporter fusions into newly identified neutral loci of the S. aureus chromosome. Insertion of the reporters does not add any antibiotic resistance genes to the chromosomes of the resultant strains, thereby making them amenable for further genetic manipulations. We used this toolbox to reconstitute the expression of mreB in S. aureus, a gene that encodes an actin-like cytoskeletal protein which is absent in coccal cells and is presumably lost during the course of speciation. We observed that in S. aureus, MreB is organized in discrete structures in association with the membrane, leading to an unusual redistribution of the cell wall material. The production of MreB also caused cell enlargement, but it did not revert staphylococcal shape. We present interactions of MreB with key staphylococcal cell wall-related proteins. This work facilitates the use S. aureus as a model system in exploring diverse aspects of cellular microbiology.

The biofilm formation defect of a Bacillus subtilis flotillin-defective mutant involves the protease FtsH.

Biofilm formation in Bacillus subtilis requires the differentiation of a subpopulation of cells responsible for the production of the extracellular matrix that structures the biofilm. Differentiation of matrix-producing cells depends, among other factors, on the FloT and YqfA proteins. These proteins are present exclusively in functional membrane microdomains of B. subtilis and are homologous to the eukaryotic lipid raft-specific flotillin proteins. In the absence of FloT and YqfA, diverse proteins normally localized to the membrane microdomains of B. subtilis are not functional. Here we show that the absence of FloT and YqfA reduces the level of the septal-localized protease FtsH. The flotillin homologues FloT and YqfA are occasionally present at the midcell in exponentially growing cells and the absence of FloT and YqfA negatively affects FtsH concentration. Biochemical experiments indicate a direct interaction between FloT/YqfA and FtsH. Moreover, FtsH is essential for the differentiation of matrix producers and hence, biofilm formation. This molecular trigger of biofilm formation may therefore be used as a target for the design of new biofilm inhibitors. Accordingly, we show that the small protein SpoVM, known to bind to and inhibit FtsH activity, inhibits biofilm formation in B. subtilis and other distantly related bacteria.