Outbreak investigation of Serratia marcescens bloodstream infection in an obstetric ward for high-risk pregnant women.

BACKGROUND: Serratia marcescens is a gram-negative bacterium that is widespread in the environment. S. marcescens bacteremia can be fatal during pregnancy and cause persistent chorioamnionitis. This study reports an outbreak of Serratia marcescens bloodstream infection (BSI) among high-risk pregnant women in an obstetric ward. The purpose of this study is to report our experience with the usefulness of the ATP test in hospital environmental management and to confirm that bloodstream infections of patients with the same strain were correlated by WGS testing. METHODS: This retrospective study collected the data of inpatients with S. marcescens bacteremia in obstetric ward for high-risk pregnant women from August 22, 2021, to October 14, 2021. We performed: an adenosine triphosphate (ATP) bioluminescence test in the environment with a high-contact area; environmental culture; on-site monitoring and staff education; and whole-genome sequencing (WGS) to evaluate genetic relationships among S. marcescens isolates. RESULTS: S. marcescens BSI occurred in four consecutive patients. None of the patients had central venous catheters. An ATP bioluminescence test revealed that high-contact areas and areas for injection preparation were not clean (≥ 1000 relative light units). However, S. marcescens was not identified in the environmental cultures, likely due to intensive environmental cleaning and discarding of potentially contaminated specimens before the culture test. On-site monitoring and education were conducted for 1 month. There were no further reports of BSI until 6 months after the last patient was discharged. WGS performed on three isolates from three patients indicated that the isolated S. marcescens was likely from the same strain. CONCLUSIONS: We controlled an S. marcescens outbreak by improving environmental cleaning as well as education of and behavior changes in healthcare workers. Using the ATP bioluminescence test can provide feedback on environmental cleaning and education. WGS played a role in determining the spread of BSI caused by the same strain.

Comparação do mecanismo de heterorresistência em Serratia marcescens por time kill curve frente ao meropeném / Comparison of heteroresistance mechanism in Serratia marcescens by time kill curve against meropenem

Serratia marcescens pertence à Família Enterobacteriaceae, é Gram-negativa e anaeróbica facultativa, sendo bem distribuída na natureza; pode ser isolada como saprófita do solo e da água. Possui um significado clínico relevante, pois acarreta infecções nosocomiais e pulmonares em determinados setores da saúde, como unidades neonatais, maternidades e UTIs, além de sepse, meningite, choque endotóxico e infecções do trato urinário. O intuito desse estudo foi analisar o mecanismo de heterorresistência em linhagens sensíveis de Serratia marcescens diante das concentrações testadas de meropeném. As linhagens SR1 e SR2 apresentaram perfil heterorresistente, ao passo que a SR6 demonstrou ser não heterorresistente, com CIM elevado (32µg/mL). Os isolados de Serratia marcescens são suscetíveis ao meropenem, por testes de sensibilidade padrão, mas contêm subpopulações resistentes ao mesmo.

Serratia marcescens belongs to the Enterobacteriaceae family, it is optional anaerobic gram-negative, being well distributed in nature and it might be isolated as saprophytic from soil and water. It has a meaningful clinical significance, because it causes nosocomial and lung infections in certain healthcare sectors, such as neonatal units, maternity units and UTIs; septicemia, meningitis, endotoxin shock and urinary tract infections. The aim of this study was to analyze the mechanism of heteroresistance in susceptible strains of Serratia marcescens in the presence of the tested concentration of meropenem. The lineages SR1 and SR2 presented heteroresistant profile, while the SR6 showed to be nonheterorresistente, with CIM (32 µg/mL). The Isolates of Serratia marcescens are susceptible to meropenem, by standard sensitivity testing, but there are subpopulations resistant to it.

Serratia Marcescens Endophthalmitis and Bacteraemia following Complicated Cataract Surgery.

A 93-year-old male presented with left eye pain, fever and loss of vision two days after complicated cataract surgery. A diagnosis of Serratia marcescens endophthalmitis and systemic bacteremia was made after the organism was identified on vitreous and peripheral blood cultures. This case demonstrates that an aggressive intraocular infection can lead to bacteremia.

Bacterial Outer Membrane Protein OmpX Regulates ß1 Integrin and Epidermal Growth Factor Receptor (EGFR) Involved in Invasion of M-HeLa Cells by Serratia proteamaculans.

Opportunistic pathogen Serratia proteamaculans are able to penetrate the eukaryotic cells. The penetration rate can be regulated by bacterial surface protein OmpX. OmpX family proteins are able to bind to host cell surface to the epidermal growth factor receptor (EGFR) and the extracellular matrix protein fibronectin, whose receptors are in return the α5 ß1 integrins. Here we elucidated the involvement of these host cell proteins in S. proteamaculans invasion. We have shown that, despite the absence of fibronectin contribution to S. proteamaculans invasion, ß1 integrin was directly involved in invasion of M-HeLa cells. Herewith ß1 integrin was not the only receptor that determines sensitivity of host cells to bacterial invasion. Signal transfer from EGFR was also involved in the penetration of these bacteria into M-HeLa cells. However, M-HeLa cells have not been characterized by large number of these receptors. It turned out that S. proteamaculans attachment to the host cell surface resulted in an increment of EGFR and ß1 integrin genes expression. Such gene expression increment also caused Escherichia coli attachment, transformed with a plasmid encoding OmpX from S. proteamaculans. Thus, an OmpX binding to the host cell surface caused an increase in the EGFR and ß1 integrin expression involved in S. proteamaculans invasion.

A promising drug delivery candidate (CS-g-PMDA-CYS-fused gold nanoparticles) for inhibition of multidrug-resistant uropathogenic Serratia marcescens.

Antibiotic resistance amongst microbial pathogens is a mounting serious issue in researchers and physicians. Various alternatives to overcome the multidrug-resistant bacterial infections are under search, and biofilm growth inhibition is one of them. In this investigation, a polymeric drug delivery system loaded with multi-serratial drugs to improve the delivery of drugs against urinary tract infection causative Serratia marcescens. The chitosan grafted pyromellitic dianhydride - cysteine (CS-g-PMDA-CYS) was conjugated with AuNPs by using the -SH group of CYS and RF (rifampicin) and INH (isoniazid) were loaded in AuNPs-fused CS-g-PMDA-CYS system. Several physicochemical techniques characterized this fabricated AuNPs/RF/INH/CS-g-PMDA-CYS system. The successful encapsulation of RF and INH in AuNPs-fused CS-g-PMDA-CYS polymer had confirmed, and it observed the loading capacity for RF and INH was 9.02% and 13.12%, respectively. The in vitro drug discharge pattern was perceived high in pH 5.5 compared with pH 7.4. The AuNPs/RF/INH/CS-g-PMDA-CYS escalates 74% of Caenorhabditis elegans survival during Serratia marcescens infection by aiming biofilm development and virulence in S. marcescens. Author postulate that the fabricated system is a promising drug carrier and delivery system for inhibition of multidrug-resistant bacterias like S. marcescens.

Lytic lesion of skull: a rare presentation of chronic granulomatous disease.

An 18-month-old boy presented with lytic lesion of skull and recurrent abscesses with Serratia marcescens The extensive work up revealed a gene mutation confirming the diagnosis of chronic granulomatous disease (CGD). This case scenario underscores the importance of exploring the possibility of immunodeficiency if there is a history of recurrent abscesses with atypical organism. The case also demonstrates that CGD can present as lytic lesion of skull.

Synergistic effects of Cinnamomum cassia L. essential oil in combination with polymyxin B against carbapenemase-producing Klebsiella pneumoniae and Serratia marcescens.

Multidrug resistance prompts the search for new sources of antibiotics with new targets at bacteria cell. To investigate the antibacterial activity of Cinnamomum cassia L. essential oil (CCeo) alone and in combination with antibiotics against carbapenemase-producing Klebsiella pneumoniae and Serratia marcescens. The antimicrobial susceptibility of the strains was determined by Vitek® 2 and confirmed by MALDI-TOF/TOF. The antibacterial activity of CCeo and its synergism with antibiotics was determined using agar disk diffusion, broth microdilution, time-kill, and checkboard methods. The integrity of the bacterial cell membrane in S. marcescens was monitored by protein leakage assay. CCeo exhibited inhibitory effects with MIC = 281.25 µg.mL-1. The association between CCeo and polymyxin B showed a decrease in terms of viable cell counts on survival curves over time after a 4 hour-treatment with a FIC index value of 0.006. Protein leakage was observed with increasing concentrations for CCeo and CCeo + polymyxin B treatments. CCeo showed antibacterial activity against the studied strains. When associated with polymyxin B, a synergistic effect was able to inhibit bacterial growth rapidly and consistently, making it a potential candidate for the development of an alternative treatment and drug delivery system for carbapenemase-producing strains.

Bacterial Actin-Specific Endoproteases Grimelysin and Protealysin as Virulence Factors Contributing to the Invasive Activities of Serratia.

The article reviews the discovery, properties and functional activities of new bacterial enzymes, proteases grimelysin (ECP 32) of Serratia grimesii and protealysin of Serratia proteamaculans, characterized by both a highly specific "actinase" activity and their ability to stimulate bacterial invasion. Grimelysin cleaves the only polypeptide bond Gly42-Val43 in actin. This bond is not cleaved by any other proteases and leads to a reversible loss of actin polymerization. Similar properties were characteristic for another bacterial protease, protealysin. These properties made grimelysin and protealysin a unique tool to study the functional properties of actin. Furthermore, bacteria Serratia grimesii and Serratia proteamaculans, producing grimelysin and protealysin, invade eukaryotic cells, and the recombinant Escherichia coli expressing the grimelysin or protealysins gene become invasive. Participation of the cellular c-Src and RhoA/ROCK signaling pathways in the invasion of eukaryotic cells by S. grimesii was shown, and involvement of E-cadherin in the invasion has been suggested. Moreover, membrane vesicles produced by S. grimesii were found to contain grimelysin, penetrate into eukaryotic cells and increase the invasion of bacteria into eukaryotic cells. These data indicate that the protease is a virulence factor, and actin can be a target for the protease upon its translocation into the host cell.

A 27-year-old man with recurrent sinopulmonary and cutaneous infections.

The increasing availability of genetic testing for modern immunologists in the evaluation of immune diseases could provide a definite diagnosis in elusive cases. A 27-year-old white male patient presented to the clinic with recurrent sinopulmonary and cutaneous infections since childhood. The patient's mother had seronegative polyarthritis, and one of two sisters of the patient had chronic sinopulmonary infections. Serum immunoglobulins, immunoglobulin G (IgG) subclasses, lymphocyte subset markers, mannose-binding lectin, mitogen and antigen stimulation, bacteriophage study, and Streptococcus pneumoniae titers to 23 serotypes were all normal. B-cell phenotyping revealed a decrease in both nonswitched memory B cells (CD19+CD27+IgD+) and switched memory B-cells (CD19+CD27+IgD-). Genetic testing and the improvement of clinical symptoms after IgG replacement led to the final diagnosis.

Rapid Detection of Microbial Contamination in Intravenous Fluids by ATP-Based Monitoring System.

In this study, we investigated four clinical cases of microbial contamination of in-use intravenous infusion fluid, detected by measuring "Adenosine triphosphate (ATP) + adenosine monophosphate (AMP)" ("ATP+AMP") levels. High "ATP+AMP" values correlate with microbial contamination, and by utilizing these values as indicator for microbial contamination possibility, we were able to rapidly detect the contamination and recommend replacement of catheters and administration sets. In three out of four cases, changing the infusion fluid led to improvement in the condition of the patients. "ATP+AMP" levels can be used to confirm microbial contamination of in-use intravenous infusion fluids, as it is fast (several minites) and convenient to measure them.

Risk Factors and Outcomes of Cutibacterium acnes Postoperative Central Nervous System Infection: A Case-Control Study.

OBJECTIVE: Cutibacterium acnes has emerged as a significant cause of postoperative central nervous system infections (PCNSIs). We sought to determine risk factors and outcomes associated with C. acnes PCNSI. METHODS: This was a single-center 1:1 case-control study of patients with monobacterial C. acnes-associated PCNSI (cases) and unmatched controls with PCNSI caused by aerobic organisms. Patient and procedure-related characteristics were compared between groups. The main outcome was cure at 90 days after diagnosis. Mortality and neurologic disability were secondary outcomes. RESULTS: We identified 13 patients with C. acnes PCNSI and 13 controls. All patients had postoperative intracranial abscess. Onset of infection was significantly later for cases versus controls (median and range, 22 [19-116] days and 15 [1-27] days, respectively; P = 0.002). Prolonged anaerobic incubation was required for C. acnes isolation (median, 8 days vs. 2 days for aerobic pathogens; P < 0.0001). The use of sealant and implants, fever at presentation, and white blood cell and C-reactive protein levels were similar between the 2 groups. All patients underwent surgical drainage. Patients received a median of 4 antibiotic drugs and 85 antibiotic days of treatment, with no significant between-group differences. Cure at 90 days was achieved for 10 patients (76.9%) with C. acnes PCNSI and 11 (84.6%) controls (P = 1.0). CONCLUSIONS: C. acnes PCNSI presents later than infection with aerobic bacteria but is associated with similar risk factors and clinical outcomes. These results underscore the importance of prolonged anaerobic incubation to optimize the recovery of C. acnes in the laboratory.

Clinical study of an outbreak of postoperative mediastinitis caused by Serratia marcescens in adult cardiac surgery.

OBJECTIVES: Nosocomial infection caused by Serratia marcescens after cardiac surgery is rare but causes high rates of morbidity and mortality. Knowledge about postoperative mediastinitis due to S. marcescens is limited. The purpose of this work was to study the clinical presentation, management and outcome of an outbreak of postoperative sternal infection due to S. marcescens. METHODS: During a 7-week period, a total of 54 patients underwent open heart procedures in our hospital. A postoperative wound infection caused by S. marcescens was diagnosed in 10 patients. We performed a clinical study to investigate patient characteristics and outcomes as well as the possible source of the infection. RESULTS: The mean age of the infected patients was 74.5 ± 10 years. Mediastinitis was present in 6 cases, superficial wound infection in 3 and isolated bacteraemia in 1. Purulent exudate through the sternal incision was observed in all infected cases except in 1 patient, who presented only with bacteraemia. Serratia marcescens was isolated from the samples taken from all infected wounds. The mean time elapsed between the operation and the isolation S. marcescens was 5.9 ± 2.4 days. Response to treatment was favourable in all cases except 1, who died. Contamination of the aqueous chlorhexidine solution used to prepare the patients' skin with S. marcescens was reported. Microbiological studies demonstrated that S. marcescens strains isolated from patients and from the aqueous chlorhexidine solution belonged to the same clone. CONCLUSIONS: The use of an aqueous chlorhexidine solution contaminated with S. marcescens caused an outbreak of postoperative sternal wound infections. The time elapsed between wound contamination and signs of infection was brief, but the systemic inflammatory response and tissue necrosis were limited. Alcohol-based solutions are recommended for the prevention of surgical site infections.

First case of Serratia liquefaciens isolated from urinary tract infection in sows and associated clinicopathological and pathological findings.

An incident of sudden deaths in the breeding stock was reported from a farrow-to-finish commercial pig farm in Greece. The 8·4% of sows during lactation and gestation period presented anorexia, fever, haematuria, return-to-oestrus and sudden deaths (mortality rate: 2·3%). Blood and urine samples were collected from four diseased sows. Furthermore, swabs from urine bladders were collected from two dead sows and four culled sows at the slaughterhouse. Blood testing demonstrated mild leucocytosis and absence of azotaemia. Urinalysis revealed haematuria, proteinuria, bilirubinuria and active urine sediment with bacilli, epithelial cells and leucocytes, crystals and granular casts. Histopathological evaluation of the bladder demonstrated chronic active polypoid cystitis. The bacterial culture revealed the presence of Serratia liquefaciens. The antibiotic susceptibility testing showed high resistance to the most common antibiotics, with the highest sensitivity of the isolate towards quinolones. After the administration of a single dose of 7·5 mg kg-1 body weight enrofloxacin intramuscularly, the mortality rate decreased to less than 0·5% along with a remarkable reduction in the severity of clinical signs. Based on our findings, S. liquefaciens induced severe clinical signs and deaths in sows, mainly due to urinary infection. Inadequate water sanitation might have been responsible for increased exposure to S. liquefaciens. SIGNIFICANCE AND IMPACT OF THE STUDY: In this study, the isolation of Serratia liquefaciens from the urinary tract of pigs associated with clinical signs and increased mortality was described for the first time. Serratia liquefaciens is an important cause of hospital-acquired human infections. The isolate in this study was resistant to the most common antibiotics. Therefore, the use of quinolones which are drugs of last resort for treatment of infections was the only therapeutic option. The presence of the resistant bacterium in the urinary tract raises concerns for its zoonotic potential.

Risk of infection in patients undergoing urologic surgery based on the presence of asymptomatic bacteriuria: A prospective study.

BACKGROUND: Treatment of asymptomatic bacteriuria (ASB) is recommended in pregnant women and prior to urologic procedures with anticipated mucosal disruption. However, there is still insufficient evidence of the usefulness of treating ASB prior to urologic procedures. Therefore, the aim of this study was to ascertain the risk of infections in patients undergoing urologic surgery based on the presence of ASB. METHODS: We conducted a cohort study among patients undergoing urologic surgery at a single center located in Medellín, Colombia. All patients were screened for ASB prior to their procedures. Patients were evaluated for the development of any postoperative infectious complications for up to 30 days after the procedure. RESULTS: A total of 149 patients were included in this cohort. Incidence of ASB was 14.8%. Thirteen patients (8.72%) developed infectious complications: 3 (13.64%) with ASB and 10 (7.87%) without ABS. Factors associated with postoperative infectious complications included urologic cancers (hazard ratio [HR], 5.26; 95% confidence intervals [CI], 1.24-22.37), urologic interventions in the preceding 3 months (HR, 3.72; 95% CI, 1.02-13.51), and use of antibiotics 3 months prior to surgery (HR, 3.83; 95% CI, 1.01-15.49). Presence of ASB was not associated with postsurgical infectious complications (HR, 1.02; 95% CI, 0.26-3.96). CONCLUSIONS: There was no association between ASB and postoperative infectious complications. There were other factors associated with infectious complications, such as urologic cancer, previous history of urologic manipulation, and antibiotic use.

Factors associated with multidrug-resistant bacteria in a cohort of patients with asymptomatic bacteriuria who underwent urological surgery.

BACKGROUND: Although the factors associated to bacterial resistance in patients with asymptomatic bacteriuria (ASB) have been studied in pregnant, fertile age women, patients with spinal cord injury, and those with urogynecological disorders, nothing is known about the factors associated with multidrug-resistant (MDR) bacteria in patients with ASB and planned urological procedures. This study therefore sought to identify the sociodemographic and clinical factors associated with MDR bacteria in a cohort of patients with ASB scheduled for urological procedures. METHODS: We conducted a nested case-control study on a cohort of patients with ASB and planned urological procedures at 3 Colombian medical centers. Cases were patients with MDR bacteria and controls were patients without MDR bacteria. RESULTS: A total of 184 patients were included, 41.8% (n = 77) of whom presented ASB with MDR bacteria. The factors linking ASB with MDR bacteria were: advanced age (odds ratio, 1.03; 95% confidence interval, 1.01-1.06) and hospitalization within the 3-month period before surgery (odds ratio, 2.35; 95% confidence interval, 1.08-5.21). CONCLUSIONS: Bacterial resistance is frequent among patients with ASB and planned urological procedures. Advanced age and prior hospitalization should be borne in mind for patients with planned urological procedures because they are factors associated with the presence of MDR bacteria.

Blowing epithelial cell bubbles with GumB: ShlA-family pore-forming toxins induce blebbing and rapid cellular death in corneal epithelial cells.

Medical devices, such as contact lenses, bring bacteria in direct contact with human cells. Consequences of these host-pathogen interactions include the alteration of mammalian cell surface architecture and induction of cellular death that renders tissues more susceptible to infection. Gram-negative bacteria known to induce cellular blebbing by mammalian cells, Pseudomonas and Vibrio species, do so through a type III secretion system-dependent mechanism. This study demonstrates that a subset of bacteria from the Enterobacteriaceae bacterial family induce cellular death and membrane blebs in a variety of cell types via a type V secretion-system dependent mechanism. Here, we report that ShlA-family cytolysins from Proteus mirabilis and Serratia marcescens were required to induce membrane blebbling and cell death. Blebbing and cellular death were blocked by an antioxidant and RIP-1 and MLKL inhibitors, implicating necroptosis in the observed phenotypes. Additional genetic studies determined that an IgaA family stress-response protein, GumB, was necessary to induce blebs. Data supported a model where GumB and shlBA are in a regulatory circuit through the Rcs stress response phosphorelay system required for bleb formation and pathogenesis in an invertebrate model of infection and proliferation in a phagocytic cell line. This study introduces GumB as a regulator of S. marcescens host-pathogen interactions and demonstrates a common type V secretion system-dependent mechanism by which bacteria elicit surface morphological changes on mammalian cells. This type V secretion-system mechanism likely contributes bacterial damage to the corneal epithelial layer, and enables access to deeper parts of the tissue that are more susceptible to infection.

RNA­seq analyses of antibiotic resistance mechanisms in Serratia marcescens.

The present study aimed to further clarify the genetic mechanisms responsible for the antimicrobial resistance of Serratia marcescens (S. marcescens) using RNA sequencing. Three drug­susceptible S. marcescens strains (named MYQT1, MYQT2, and MYQT3) and three multidrug­resistant S. marcescens strains (named MYQT4, MYQT5, and MYQT6) were isolated from six different patients and subjected to RNA sequencing. Differentially expressed genes (DEGs) between the multidrug­resistant S. marcescens strains and drug­susceptible strains were screened and compared, followed by functional enrichment analysis. In addition, a protein­protein interaction (PPI) network was constructed, and significant modules were extracted from it. Genes enriched in the significant modules were subjected to further enrichment analysis. MYQT3 had very a different expression pattern from MYQT1 and MYQT2, and thus, MYQT3 was excluded from the following analysis. A total of 225 DEGs were identified, of which SMDB11_RS09300 (GTP cyclohydrolase FolE2) was the most significantly upregulated with a log2 FC of 6.4; these DEGs were enriched in different GO terms, including hydrogen sulfide biosynthetic process, sulfur compound transmembrane transporter activity, and ABC transporter complex. Additionally, several genes were identified to be important genes in the PPI network, including SMDB11_RS17755 (upregulated; glutamate synthase large subunit), SMDB11_RS00590 (upregulated; sulfite reductase subunit α), and SMDB11_RS04505 (upregulated; cystathionine ß­synthase). Thus, SMDB11_RS09300, SMDB11_RS17755, SMDB11_RS00590, and SMDB11_RS04505 may play significant roles in the antimicrobial resistance of S. marcescens by participating in folate metabolism or the integrity of cell membranes. However, further experiments are required to clarify these findings.