Marcescens Isolates Research Articles

Molecular Characterization of Carbapenem-Resistant Serratia marcescens Clinical Isolates in a Tertiary Hospital in Hangzhou, China.

IntroductionAlthough carbapenem-resistant Enterobacteriaceae (CRE) have been thoroughly investigated as the pathogens most commonly associated with clinical infections, data on Serratia marcescens are inadequate and superficial.MethodsIn this study, we characterized 36 carbapenem-resistant Serratia marcescens (CRSM) isolates in our hospital from April 2018 to March 2019 by analysing whole-genome sequencing (WGS) data. The molecular typing of the isolates was performed using both pulsed-field gel electrophoresis (PFGE) and core genome multilocus sequence typing (cgMLST).ResultsThirty-three of the 36 isolates showed carbapenem resistance conferred by a blaKPC-2-harbouring plasmid, while the remaining three isolates were characterized by overexpression of beta-lactamase combined with porin loss. The blaKPC-2 genes in all the isolates were located on a plasmid of ~103 kb, except one, which was on a plasmid of ~94 kb. The gene structure surrounding blaKPC-2 in the plasmids was confirmed by integration of a partial Tn4401 structure and an intact IS26 as previously reported. Most of the plasmids also contained a mobile genetic element (MGE) comprising qnr and ISKpn19, which provided evidence of horizontal transfer of antibiotic resistance genes.ConclusionThe thirty-six CRSM isolates were mainly clonally disseminated with a blaKPC-2-harbouring plasmid in our hospital. The gene structure surrounding blaKPC-2 as an MGE, as well as the qnr segment, might be acquired by horizontal gene transfer, and it could aggravate the infection and increase the difficulty of clinical treatment.

Bacteriology of Some Liquid Herbal Products Sold in Ilorin- Kwara State Nigeria

Purpose: This study aims to establish the safety and/or potential public health dangers associated with the consumption of liquid herbal preparations (LHP) sold in Ilorin-Kwara State. Methods: Ten LHPs were randomly collected from three locations, kept under cold chain and transported to the Laboratory. All samples were evaluated for bacterial load using aerobic plate count method and bacterial isolates were presumptively identified using standard microbiological methods. Furthermore, Gram negative bacteria were identified using 12A Microbact ® Identification kits. Results: Sixty percent (60%) were fresh and faint, 4 (40%) were stale and putrid in smell as well as free of foreign matter. pH and bacterial load of samples ranged from 3.60 to 9.75 and 2.5 x 102 to 4.4 x 106 CFU/ mL respectively. Five (5) genera of bacteria, namely; Klebsiella species 10 (29.41%), Bacillus subtilis 8 (23.53%), Enterobcter spps. 7 (20.59%), Staphylococcus aureus 6 (17.65%) and Serretia marcescens 3(8.82%) were isolated from these LHPs. All isolates were resistant (100%) to Sulphamethoxazole trimethoprim combination. Amoxocillin clavulanate was active against 62.50% of K. pneumonia and S. marcescens isolates. Also 50% of K. oxytoca and E. gergoviae were susceptible to Amoxocillin clavulanate combination. Approximately, 8 (80%) of LHPs had bacterial load of 2.5 x 102 to 4.4 x 106 CFU/ mL and 2 (20%) yielded no growth. In addition, 40% of LHPs had bacterial load of 106 CFU/mL beyond the 104 CFU/mL permissible limit stated by European Pharmacopoeia. Conclusion: The observed high bacterial load and the presence of S. aureus as well as enteric bacteria of public health importance in these LHPs underscore the potential risk inherent in the consumption of these preparations. Therefore, public health awareness campaign on the dangers of unapproved LHPs consumption should be instituted. Keywords: Liquid herbal preparations, bacterial contaminants, Ilorin metropolis

Description of two Serratia marcescens associated mastitis outbreaks in Finnish dairy farms and a review of literature

BackgroundInfection with Serratia spp. have been associated with mastitis outbreaks in dairy cattle herds. Environmental contamination or a point source, like a teat dip product, have often been observed to be potential sources of such outbreaks. We describe two Serratia marcescens associated mastitis outbreaks associated with a contaminated teat dip containing a tertiary alkyl amine, n,n-bis (3-aminopropyl) dodecylamine in two dairy cattle farms in Finland. S. marcescens strains isolated from milk and environmental samples were identified by the MALDI-TOF method.ResultsSix specimens (n = 19) on Herd 1 and all specimens (n = 9) on Herd 2 were positive for S. marcescens. Positive specimens were from mastitis milk and teat dip liquid and equipment. Bacteria were not isolated from the unopened teat dip canister. The same clone of S. marcescens was isolated from milk samples and teat dip samples within the farms. Pulsed field gel electrophoresis results to the S. marcescens isolates from these two different herds were tested with unweighted pair-group method using arithmetic average clustering analysis. The isolates were not same clone in both herds, because similarity in that test was only 75% when cut-off value to similarity is 85%.ConclusionsOur investigation showed that the post milking teat dip and/or temporary containers were contaminated with S. marcescens and these were most likely the sources for new mastitis cases. The negative result from the unopened teat dip canister and positive results from refillable containers demonstrated that the product itself was not contaminated with S. marcescens at the production unit, but became contaminated at the farm level.

2460. Hospital-Wide Outbreak of Serratia marcescens of Unclear Source: When Extensive Infection Control Measures Are Needed

BackgroundNosocomial outbreaks of Serratia marcescens have been widely reported and the source is identified in most cases. We report a Serratia marcescens outbreak in a community hospital with no obvious source.MethodsAn epidemiologic investigation was started after an outbreak was suspected. Clinical data were collected from charts of patients with positive culture for Serratia marcescens. Molecular relatedness of available isolates was determined by pulsed-field gel electrophoresis.ResultsBetween December 2016 and August 2017, 13 non-pigmented Serratia marcescens isolates were identified from 11 patients. Bacteria were isolated from blood, abdominal and respiratory cultures. Susceptibility profiles showed variable resistance to ceftriaxone, ceftazidime, imipenem, tobramycin and aztreonam. Infection control measures: Isolates were identified from adult patients who underwent various cardiothoracic/vascular surgeries. Patients were traced back to a single floor of the new hospital building. To control this outbreak, the infection prevention team started with hand hygiene initiatives and observations, environmental sampling, and reviewing management of ventilator, dialysis equipment, and ECMO machines. Ice machine carbonless filters were installed, UV disinfection systems were used, and new TEE cleaning rooms were designated. In conjunction with recommendations of department of health, hospital was contracted with a water cleaning company; laminar flow aerators were installed, water sampling plan was implemented and ultimately the whole building’s water system was hyper-chlorinated.ConclusionWhile water contamination was the most likely source, a specific cause could not be identified. An important lesson learnt is the quick implementation of infection control measures after identifying infected patients is key in controlling an outbreak.Disclosures All authors: No reported disclosures.

ISOLATION AND IDENTIFICATION OF EGYPTIAN STRAINS OF Serratia marcescens PRODUCING ANTIBACTERIAL AND ANTIOXIDANT PRODIGIOSIN PIGMENT

Prodigiosin is a natural red pigment, it is an alkaloid secondary metabolite with a unique tripyrrole structure produced by Serratia marcescens, it’s motile, short-rod shaped, G- bacteria, classified in the large family of Enterobacteriaceae. 13 isolates were isolated from 32 soil samples, which showed clear red pigmented colonies. The Egyptian Serratia marcescens isolates were identified based on morphological, biochemical and then only the two best isolates for pigment production (M1, S1) were identified by MALDI-TOF mass spectrometry technique. The two selected species gave a score value between 2.565 to 2.668 (100%) were correctly identified by MALDI-TOF- MS to the genus and species levels. The average daily rate of pigment production by M1 and S1 isolates estimated by 421.6 and 326.1 unit/cell, respectively. Antibacterial activity of prodigiosin was determined by disc diffusion assay against 7 types of G- and 4 types of G+ pathogenic bacteria. Minimum inhibitory concentration (MIC) and the concentration inducing 50% inhibition of the bacterial growth (IC50)against the mentioned bacteria were determined and prodigiosin was proved to be effective in inhibiting bacterial growth. Prodigiosin possess antioxidant activity assayed by 2,2-diphenyl-1-picrylhydrazyl (DPPH) reduction method and this activity increased gradually with increasing concentrations.

93 EXPLORING THE RELATIONSHIP BETWEEN RARE DELETERIOUS CODING VARIATION AND COMMON CIS-REGULATORY VARIATION IN SCHIZOPHRENIA

A carbapenem-resistant S. marcescens isolate was recovered from a patient with an inflammed pacemaker inplantation pocket from a Cardiac Surgery ward in a Hungarian University Hospital. Phenotypic tests and polymerase chain reaction (PCR) confirmed a very rare gene responsible for production of a carbapenemase (blaVIM-4), which was further characterized by Sanger-sequencing. The characterization of this S. marcescens strain emphasizes the ongoing emergence of novel or rare carbapenemases. Strains expressing a weak carbapenemase like this strain might go unrecognized by routine diagnostics due to low minimum inhibitory concentrations (MICs) for the bacterial strains producing such enzymes.

Association of blaNDM-1 with blaKPC-2 and aminoglycoside-modifying enzyme genes among Klebsiella pneumoniae, Proteus mirabilis and Serratia marcescens clinical isolates in Brazil

ObjectivesCarbapenemase-producing Enterobacterales are frequently involved in healthcare-associated infections worldwide. The objectives of this study were to investigate (i) the frequency of the main genes encoding carbapenemases, 16S rRNA methylases and aminoglycoside-modifying enzymes (AMEs) as well as the mcr gene and (ii) the clonal relationship of enterobacteria isolates resistant to carbapenems and aminoglycosides from colonisation and infection in patients from hospitals in northeastern Brazil. MethodsAntimicrobial susceptibility was determined using an automated VITEK®2 system. Presence of carbapenemase, AME and 16S rRNA methylase genes as well as the mcr gene was determined by PCR and amplicon sequencing. Genetic variability was determined by ERIC-PCR. ResultsA total of 35 isolates resistant to carbapenems and aminoglycosides were selected for this study. Klebsiella pneumoniae was most common (45.7%), followed by Proteus mirabilis (28.6%) and Serratia marcescens (25.7%). AME genes were found in 97.1% of isolates, most commonly aph(3ʹ)-VI and aac(6')-Ib. The blaNDM-1 and blaKPC-2 genes were detected in 25.7% and 88.6% of isolates, respectively; five isolates harboured these genes concomitantly. According to the literature, this is the first report of the association of blaNDM-1 and blaKPC-2 in P. mirabilis and S. marcescens in Brazil. The isolates showed a multiclonal profile by ERIC-PCR. ConclusionThe emergence of blaNDM-1 associated with blaKPC-2 and AME genes in K. pneumoniae, P. mirabilis and S. marcescens isolates with a multiclonal profile is of concern as this limits therapeutic options. These results should alert medical authorities to establish rigorous detection methods to reduce the spread of these antimicrobial resistance genes.

Potential of five non-spore-forming bacteria, originated from the European cockchafer, Melolontha melolontha (Linnaeus, 1758) (Coleoptera: Scarabaeidae), on three economic insect pests

Five non-spore-forming bacteria were isolated from the European cockchafer, Melolontha melolontha (Linnaeus, 1758) (Coleoptera: Scarabaeidae). Their potential was tested against the three economic insect pests, the great spruce bark beetle, Dendroctonus micans Kugelann (Coleoptera: Curculionidae); the pine processionary, Thaumetopoea pityocampa (Lepidoptera: Thaumetopoeidae); and the gypsy moth, Lymantria dispar (Linn.) (Lepidoptera: Erebidae), to find an effective biological control agent. All isolated bacteria were cultured and identified using VITEK bacterial identification systems and 16S rRNA gene sequence analysis. The bacteria were identified as Enterobacter cloacae complex (isolate 1M), Serratia marcescens (isolate 3M), Pseudomonas aeruginosa (isolate 4M), Kocuria kristinae (isolate 5M), and Serratia liquefaciens (isolate 8M). Laboratory experiments, carried out to evaluate the virulence of these isolates, showed that all isolated bacteria had a pathogenic effect on the tested pests. E. cloacae had 35, 56.7, and 84%; S. marcescens 50, 60.9, and 47.8%; P. aeruginosa 55, 69.6, and 48%; K. kristinae 40, 43.5, and 16%; and S. liquefaciens 45, 65.2, and 36% mortality rates on the larvae of D. micans, T. pityocampa, and L. dispar, respectively. The isolated bacteria can be considered in integrated pest control programs.

Serratia marcescens colonization in preterm neonates during their neonatal intensive care unit stay

BackgroundNosocomial sepsis is the main problem that preterms have to face during their stay at neonatal intensive care units (NICU). Serratia marcescens is an emerging cause of preterm sepsis but its epidemiology is still largely unknown. Consequently, the aims of this study were to know the rate of preterms colonized by S. marcescens during their stay at the NICU and the characteristics and evolution of the S. marcescens population, including the susceptibility to clinically relevant antibiotics.MethodsTwenty-six preterm infants born with a gestational age ≤ 32 weeks and/or weigh ≤1500 g were included in the study. Samples of meconium and feces (n = 92) were collected during their first month of life of the infants, together with feeding samples after their pass through enteral feeding tubes (n = 37). Samples were inoculated on MacConkey agar plates. The isolates identified as S. marcescens were genotyped using RAPD and PFGE; and antibiotics susceptibility was performed in a Vitek 2 system.ResultsA total of 179 S. marcescens isolates were obtained from the samples. PFGE profiling and cluster analysis allowed the classification of the isolates into 7 different S. marcescens clones. PFGE patterns 1 and 3 were the dominant strains in the fecal samples colonizing 31 and 35% of the infants, respectively. Those isolates causing bacteremia in two infants clustered in PFGE pattern 3.ConclusionS. marcescens is a bacterial species closely associated to the NICU environment. It can be frequently isolated from preterm’s feces although only some genetic lineages seem to be associated to sepsis. Enteral feeding tubes act as important reservoirs to keep the S. marcescens population in the NICU.Trial registrationThe local ethic committee approved this trial with the reference 09/157.

Synergistic Effect of Ceftazidime-Avibactam with Meropenem against Panresistant, Carbapenemase-Harboring Acinetobacter baumannii and Serratia marcescens Investigated Using Time-Kill and Disk Approximation Assays.

Susceptibility of ceftazidime-avibactam and in vitro synergy with meropenem were investigated using disk approximation and time-kill assays against 11 multiresistant Acinetobacter baumannii isolates harboring oxacillinases and 5 Serratia marcescens isolates carrying blaKPC-2 Ceftazidime-avibactam was very active and synergistic with meropenem against multiresistant S. marcescens isolates. On the other hand, only the A. baumannii isolates coharboring blaOXA-23 and blaOXA-117 displayed synergy. The disk approximation technique presented good sensitivity for synergism in S. marcescens infection.

Draft Genome Sequences of 38 Serratia marcescens Isolates Associated with Acroporid Serratiosis.

Serratia marcescens is a Gram-negative bacterium causally linked to acroporid serratiosis, a form of white pox disease implicated in the decline of elkhorn corals. We report draft genomes of 38 S. marcescens isolates collected from host and nonhost sources. The availability of these genomes will aid future analyses of acroporid serratiosis.

Endophytic bacterial consortium as biological control to Ralstonia solanacearum and growth promoter for chili plant

Resti Z, Sulyanti E, Reflin. 2018. Endophytic bacterial consortium as biological control to Ralstonia solanacearum andgrowth promoter for chili plant. Pros: Biodiv Indon 4: 208-214. The bacterial wilt disease caused by Ralstonia solanacearum (Smith) isan important disease in chili which can cause yield losses of up to more than 90%. Control of wilt disease is still using pesticides thatcan cause environmental pollution, and even endanger human health. Therefore, it is necessary to find an alternative environmentallyfriendly control, which in this study uses biological control with endophytic bacteria consortium. The aim of the study was to obtainendophytic bacteria that were compatible as a consortium of biological controllers R. solanacearum and plant growth promoters. Thefirst stage of the experiment was the compatibility test between different strains of endophytic bacteria, and hemolysis testing usingdescriptive methods. The second stage of the experiment was testing the ability of endophytic bacteria consortium to R. solanacearumpathogens causing wilting in chili, using the paper dish methods. Testing ability to promote growth using experimental method withCompletely Randomized Design (CRD). Eight treatments and 10 replications for the nursery phase. 9 treatments and 4 replications inthe planting phase. The treatment is an endophytic bacterial consortium namely; A: S. marcescens isolates ULG1E2 + S. marcescensisolates ULG1E4, B: S. marcescens isolates ULG1E2 + S. marcescens isolates JB1E3, C; S. marcescens isolates ULG1E4 + S.marcescens isolates JB1E3, D; S. marcescens isolates ULG1E2 + S. marcescens isolates ULG1E4 + S. marcescens isolates JB1E3, E;Bacillus sp SJI + Bacillus sp HI, F; Bacillus sp SJI + S. marcescens isolate JB1E3, G: SJI Bacillus sp + Bacillus sp HI + S. marcescensisolate JB1E3, Control (without Consortium). The results showed that endophytic bacterial consortium was able to suppress thedevelopment of R. solanacearum, improve seedling development and chili plant growth. Endophytic bacteria consortium C (S.marcescens isolates ULG1E4 + S. marcescens isolates JB1E3) were able to improve the development of chilli seeds. Endophyticbacterial consortium F (Bacillus sp SJI + S. marcescens isolates JB1E3) and G: (Bacillus sp SJI + Bacillus HI + S. marcescens sp.isolate JB1E3), was able to suppress the development of R. solanacearum and increase the high growth of chili plant 38.38% and thenumber of leaves of chili plants 70%.

1196. Serratia marcescens Strains Carrying blaKPC-2 and blaKPC-3 Carbapenemase Associated With Chronic Mechanical Ventilation

BackgroundCarbapenem resistance (CR) in Enterobacteriaceae is a growing concern which the CDC has designated as an urgent threat. At our institution we have noted emergence of CR strains in clinical isolates including a growing number of Serratia marcescens. CR in Serratia marcescens in the United States is mostly reported to be encoded by the SME family of chromosomally encoded carbapenemases, while in Asia it has been described being mediated by transmissible plasmids such as KPC. Here we describe the emergence and characteristics of CR Serratia marcescens at an academic tertiary care hospital in New York.Methods Serratia marcescens isolates demonstrating in vitro carbapenem resistance were recovered over a 12-month period from six distinct patients. Antibiotic resistance was determined by standard methods. Real-time PCR for bla(KPC), mcr gene, bla(NDM-1), bla(VIM), and bla(OXA-48) was performed. Patient comorbidities, source of culture, location in the hospital, and co-infection with other CR organisms were investigated.ResultsFourteen S. marcescens isolates demonstrating in vitro carbapenem resistance were recovered from six individual patients. All six patients had a history of chronic respiratory failure with tracheostomy and at least partial ventilator dependence. Five of the patients were located on the pulmonary intermediate care unit, and one in the pediatric intensive care unit. Twelve of the 14 isolates were tracheal or sputum cultures. Five of the sputum cultures from two patients were co-infected with CR Pseudomonas, and one sputum culture was simultaneously positive for CR Klebsiella pneumoniae and Enterobacter Cloacae. Nine out of 14 isolates were positive for blaKPC-3, two were blaKPC-2 positive, and three were blaKPC-negative, with no mechanism of carbapenem resistance determined yet. None of the other genes were detected.ConclusionMost carbapenem-resistant Serratia isolates were derived from respiratory tract and were found to be positive for blaKPC-3. This suggests that plasmid encoded carbapenemases are emerging among Serratia in the United States, which is already being reported in China. Genomic sequencing may establish whether this represents a clonal expansion and whether the blaKPC plasmid was transferred from Klebsiella or Enterobacter to Serratia in one of the patients.Disclosures All authors: No reported disclosures.

First reported nosocomial outbreak of Serratia marcescens harboring bla IMP-4 and bla VIM-2 in a neonatal intensive care unit in Cairo, Egypt.

IntroductionSerratia marcescens is a significant hospital-acquired pathogen, and many outbreaks of S. marcescens infection have been reported in neonates. We report a sudden breakout of S. marcescens harboring the blaIMP-4 and blaVIM-2 metallo-β-lactamase (MBL) genes that occurred from March to August 2015 in the neonatal intensive care unit of Cairo University Hospital, Cairo, Egypt.MethodsDuring the study period, 40 nonduplicate clinical isolates of S. marcescens were collected from blood culture samples. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was used to identify each isolate. Then, minimum inhibitory concentrations of different antibiotics were assessed by the Vitek 2 compact system. Screening of the MBL genes blaIMP, blaVIM, blaSIM-1, blaSPM-1, and blaGIM-1 as well as the carbapenemase genes KPC, NDM, OXA-48, SME-1, and SME-2 were evaluated. Pulsed field gel electrophoresis was preformed to detect the genetic relationship of the isolates.ResultsAnalysis showed that 37.5% of the S. marcescens clinical isolates were resistant to meropenem (minimum inhibitory concentrations ≥ 2 µg/mL), and blaIMP-4 and blaVIM-2 were the most prevalent MBL genes (42.5% and 37.5%, respectively). None of the other investigated genes were observed. Pulsed field gel electrophoresis typing revealed two discrete clones; 33/40 (82.5%) were pulsotype A and 7/40 (17.5%) were pulsotype B.ConclusionHere, we report for the first time the detection of MBL-producing S. marcescens isolates, particularly IMP-4 and VIM-2 recovered from inpatients with bacteremias from the intensive care unit at Cairo University Hospital.

Sink traps as the source of transmission of OXA-48-producing Serratia marcescens in an intensive care unit.

Carbapenemase-producing Enterobacteriaceae (CPE) outbreaks are mostly attributed to patient-to-patient transmission via healthcare workers. We describe successful containment of a prolonged OXA-48-producing S. marcescens outbreak after recognizing the sink traps as the source of transmission. The Sheba Medical Center intensive care unit (ICU), contains 16 single-bed, semi-closed rooms. Active CPE surveillance includes twice-weekly rectal screening of all patients. A case was defined as a patient detected with OXA-48 CPE >72 hours after admission. A root-cause analysis was used to investigate the outbreak. All samples were inoculated on chrom-agar CRE, and carbapenemase genes were detected using commercial molecular Xpert-Carba-R. Environmental and patient S. marcescens isolates were characterized using PFGE. From January 2016 to May 2017, 32 OXA-48 CPE cases were detected, and 81% of these were S. marcescens. A single clone was the cause of all but the first 2 cases. The common factor in all cases was the use of relatively large amounts of tap water. The outbreak clone was detected in 2 sink outlets and 16 sink traps. In addition to routine strict infection control measures, measures taken to contain the outbreak included (1) various sink decontamination efforts, which eliminated the bacteria from the sink drains only temporarily and (2) educational intervention that engaged the ICU team and lead to high adherence to 'sink-contamination prevention guidelines.' No additional cases were detected for 12 months. Despite persistence of the outbreak clones in the environmental reservoir for 1 year, the outbreak was rapidly and successfully contained. Addressing sink traps as hidden reservoirs played a major role in the intervention.

Microextraction by Packed Sorbent (MEPS) for the determination of Polybrominated Diphenyl Ether (PBDE) in eggs by Gas Chromatography-Mass Spectrometry (GC-MS)

We evaluated the genetic environment of blaGES-16 found in 2 carbapenem-resistant Serratia marcescens clinical isolates recovered from patients hospitalized at a tertiary hospital located in Rio de Janeiro, Brazil. We also compared the kinetics constants for GES-16 and GES-5 against several β-lactams. Both S. marcescens isolates showed identical PFGE pattern and carried the carbapenemase-encoding gene blaGES-16 and the extended-spectrum β-lactamase encoding gene blaOXA-10. The blaGES-16 was inserted at the first position of a defective class 1 integron, composed by a fragmented integrase gene that lacked its attI1 recombination site, followed by dfr22, aac(6′)-IIc, and aadA1 genes. This integron was located on a 30-kb nonconjugative plasmid. The GES-16 showed 2 amino acid substitutions (Gln38Glu and Gly170Ser) compared to GES-1. Kinetic analysis showed that GES-16 presented hydrolytic activity against all β-lactams tested, except for aztreonam. Imipenem was the carbapenem more efficiently hydrolyzed (highest kcat/Km) by GES-16. The kinetic parameters of GES-16 were similar to those of GES-5. In conclusion, we identified a new GES-type enzyme with carbapenemase activity in S. marcescens. The increasing diversity of such resistance determinants confirms the ongoing evolution of these β-lactamases towards a broader spectrum of activity.

Serratia marcescens Outbreak in a Neonatal Intensive Care Unit: New Insights from Next-Generation Sequencing Applications.

Serratia marcescens is an environmental bacterium that is commonly associated with outbreaks in neonatal intensive care units (NICUs). Investigations of S. marcescens outbreaks require efficient recovery and typing of clinical and environmental isolates. In this study, we investigated how the use of next-generation sequencing applications, such as bacterial whole-genome sequencing (WGS) and bacterial community profiling, could improve S. marcescens outbreak investigations. Phylogenomic links and potential antibiotic resistance genes and plasmids in S. marcescens isolates were investigated using WGS, while bacterial communities and relative abundances of Serratia in environmental samples were assessed using sequencing of bacterial phylogenetic marker genes (16S rRNA and gyrB genes). Typing results obtained using WGS for the 10 S. marcescens isolates recovered during a NICU outbreak investigation were highly consistent with those obtained using pulsed-field gel electrophoresis (PFGE), the current standard typing method for this bacterium. WGS also allowed the identification of genes associated with antibiotic resistance in all isolates, while no plasmids were detected. Sequencing of the 16S rRNA and gyrB genes both showed greater relative abundances of Serratia at environmental sampling sites that were in close contact with infected babies. Much lower relative abundances of Serratia were observed following disinfection of a room, indicating that the protocol used was efficient. Variations in the bacterial community composition and structure following room disinfection and among sampling sites were also identified through 16S rRNA gene sequencing. Together, results from this study highlight the potential for next-generation sequencing tools to improve and to facilitate outbreak investigations.

Production and Partial Purification of Tannase from Serratia Marcescens Isolated from Different Sources

Tannase has different benefits in food, chemical and pharmaceutical fields. Seventeen Serratia marcescens isolates were collected from septicemia, wound infections and hospital environment(babies incubators).These isolates were identified by biochemical tests and Vitek 2 system that contained Vitek GNI card then conformed by16S rRNA gene products(amplified size 179 bp) for genotypic detection. After that, they screened for higher tannase production and Serratia marcescens b9 was a better producer of tannase with a larger diameter of a dark green zone. The tannase activity was increased to 63U/ml when this isolate was cultivated under the optimal conditions which consisted of using nutrient broth supplemented with ber leaves at pH value 5.5 and a temperature equals to 37°C for 72 hours. In the partial purification of tannase, ammonium sulfate was more efficient than organic solvents, since it was found that 70% saturation of ammonium sulfate led to precipitate of tannase with tannase activity of 80U/ml. In contrast, 30% of ethanol, acetone, and isopropanol led to precipitate of tannase with different levels of activity ranged between 45-47U/ml. Consequently, ber leaves have a potential as an effective and much cheaper (economical) substrate for tannase production in comparison with traditionally used substrates like tannic acid.

Clonal Background, Resistance Gene Profile, and Porin Gene Mutations Modulate In Vitro Susceptibility to Imipenem-Relebactam in Diverse Enterobacteriaceae.

Treatment options for carbapenem-resistant Enterobacteriaceae (CRE) are limited. While Klebsiella pneumoniae strains harboring blaKPC account for most CRE, recent evidence points to increasing diversification of CRE. We determined whether the CRE species and antibiotic resistance genotype influence the response to relebactam (REL), a novel beta-lactamase inhibitor with class A/C activity, combined with imipenem-cilastatin (IMI). We carried out broth microdilution testing with IMI alone or in the presence of 4 μg/ml REL against 154 clinical isolates collected at a New York City hospital with a high prevalence of organisms carrying blaKPC, including Enterobacter spp. (n = 96), K. pneumoniae (n = 44), Escherichia coli (n = 1), Serratia marcescens (n = 9), and Citrobacter spp. (n = 4). Resistance gene profiles and the presence of major porin gene disruptions were ascertained by whole-genome sequencing. Addition of REL decreased the IMI MIC to the susceptible range (≤1 μg/ml) against 88% of isolates. However, S. marcescens IMI-REL MICs were 4- to 8-fold higher than those for other organisms. Most blaKPC-positive isolates had IMI-REL MICs of ≤1 μg/ml (88%), including isolates of Enterobacter cloacae ST171 (93%) and K. pneumoniae ST258 (82%). Nineteen isolates had IMI-REL MICs of ≥2 μg/ml, among which 84% harbored blaKPC and one was blaNDM-1 positive. Isolates with IMI-REL MICs of ≥2 μg/ml versus those with MICs of ≤1 μg/ml were significantly more likely to demonstrate disruption of at least one porin gene (42% versus 19%; P = 0.04), although most S. marcescens isolates (67%) had intact porin genes. In conclusion, while REL reduced IMI MICs in a majority of diverse CRE isolates, including high-risk clones, chromosomal factors had an impact on IMI-REL susceptibilities and may contribute to elevated MICs for S. marcescens.

Genetic and biochemical characterization of GES-16, a new GES-type β-lactamase with carbapenemase activity in Serratia marcescens

We evaluated the genetic environment of blaGES-16 found in 2 carbapenem-resistant Serratia marcescens clinical isolates recovered from patients hospitalized at a tertiary hospital located in Rio de Janeiro, Brazil. We also compared the kinetics constants for GES-16 and GES-5 against several β-lactams. Both S. marcescens isolates showed identical PFGE pattern and carried the carbapenemase-encoding gene blaGES-16 and the extended-spectrum β-lactamase encoding gene blaOXA-10. The blaGES-16 was inserted at the first position of a defective class 1 integron, composed by a fragmented integrase gene that lacked its attI1 recombination site, followed by dfr22, aac(6′)-IIc, and aadA1 genes. This integron was located on a 30-kb nonconjugative plasmid. The GES-16 showed 2 amino acid substitutions (Gln38Glu and Gly170Ser) compared to GES-1. Kinetic analysis showed that GES-16 presented hydrolytic activity against all β-lactams tested, except for aztreonam. Imipenem was the carbapenem more efficiently hydrolyzed (highest kcat/Km) by GES-16. The kinetic parameters of GES-16 were similar to those of GES-5. In conclusion, we identified a new GES-type enzyme with carbapenemase activity in S. marcescens. The increasing diversity of such resistance determinants confirms the ongoing evolution of these β-lactamases towards a broader spectrum of activity.