Lactococcus lactis catheter-related bacteremia in an infant

Preparation and In Vitro Characterization of Lactococcus lactis-Loaded Alginate Particles as a Promising Delivery Tool for Periodontal Probiotic Therapy

Probiotic microorganisms are used in a variety of food supplements and medical formulations to promote human health. In periodontal therapy, probiotics are mainly used in the form of gels, tablets or rinses that often tend to leak from the periodontal pocket, resulting in a strongly reduced therapeutic effect. In this pilot in vitro study, we present biodegradable alginate-based particles as an alternative, highly efficient system for a periodontal delivery of probiotic bacteria to the inflammation site. For this purpose, Lactococcus (L.) lactis was encapsulated using a standardized pump-controlled extrusion-dripping method. Time-dependent bacterial release in artificial saliva was investigated over 9 days. The effect of freeze drying was explored to ensure long-term storage of L. lactis-loaded particles. Additionally, the particles were bound to dentin surface using approved bioadhesives and subjected to shear stress in a hydrodynamic flow chamber that mimics the oral cavity in vitro. Thus, round particles within the range of 0.80-1.75 mm in radius could be produced, whereby the diameter of the dripping tip had the most significant impact on the size. Although both small and large particles demonstrated a similar release trend of L. lactis, the release rate was significantly higher in the former. Following lyophilization, particles could restore their original shape within 4 h in artificial saliva; thereby, the bacterial viability was not affected. The attachment strength to dentin intensified by an adhesive could resist forces between 10 and 25 N/m2. Full degradation of the particles was observed after 20 days in artificial saliva. Therefore, alginate particles display a valuable probiotic carrier for periodontal applications that have several crucial advantages over existing preparations: a highly stable form, prolonged continuous release of therapeutic bacteria, precise manufacturing according to required dimensions at the application site, strong attachment to the tooth with low risk of dislocation, high biocompatibility and biodegradability.

Lactococcus lactis, a bacterium with probiotic functions and pathogenicity

Lactococcus lactis (L. lactis) is the primary organism for lactic acid bacteria (LAB) and is a globally recognized safe microorganism for the regulation of the intestinal micro-ecological balance of animals and improving the immune performance of the host. L. lactis is known to play a commercially important role in feed fortification, milk fermentation, and vaccine production, but pathogenic L. lactis has been isolated from many clinical cases in recent years, such as the brain of silver carp with Lactococcosis, the liver and spleen of diseased waterfowl, milk samples and padding materials with cow mastitis, and blood and urine from human patients with endocarditis. In dairy farming, where L. lactis has been used as a probiotic in the past, however, some studies have found that L. lactis can cause mastitis in cows, but the lack of understanding of the pathogenesis of mastitis in cows caused by L. lactis has become a new problem. The main objective of this review is to analyze the increasingly serious clinical mastitis caused by L. lactis and combined with the wide application of L. lactis as probiotics, to comprehensively discuss the characteristics and diversity of L. lactis.

Diversity of the bacteriocins, their classification and potential applications in combat of antibiotic resistant and clinically relevant pathogens

There is almost a century since discovery of penicillin by Alexander Fleming, a century of enthusiasm, abuse, facing development of antibiotic-resistance and clear conclusion that the modern medicine needs a new type of antimicrobials. Bacteriocins produced by Gram-positive and Gram-negative bacteria, Archaea and Eukaryotes were widely explored as potential antimicrobials with several applications in food industry. In last two decades bacteriocins showed their potential as promising alternative therapeutic for the treatment of antibiotic-resistant pathogens. Bacteriocins can be characterised as highly selective antimicrobials and therapeutics with low cytotoxicity. Most probably in order to solve the problems associated with the increasing number of antibiotic-resistant bacteria, the application of natural or bioengineered bacteriocins in addition to synergistically acting preparations of bacteriocins and conventional antibiotics, can be the next step in combat versus drug-resistant pathogens. In this overview we focussed on diversity of specific lactic acid bacteria and their bacteriocins. Moreover, some additional examples of bacteriocins from non-lactic acid, Gram-positive and Gram-negative bacteria, Archaea and eukaryotic organisms are presented and discussed. Therapeutic properties of bacteriocins, their bioengineering and combined applications, together with conventional antibiotics, were evaluated with the scope of application in human and veterinary medicine for combating (multi-)drug-resistant pathogens.

Lactococcus lactis Endocarditis in an Immunocompromised Patient

Lactococcus lactis infections are rarely reported in the medical literature. L. lactis is a commonly used fermenting agent which may be difficult to identify with common microbiology identification processes. This factor may contribute to its lack of recognition in medical journals. We report a case of an immunosuppressed 80-year-old female with L. lactis bacteremia, subsequently, found to have aortic valve vegetation, who responded clinically to a six-week duration of ceftriaxone therapy. Afterward, a brief updated literature review is presented on L. lactis infections.

Lactococcus Species Central Line-Associated Bloodstream Infection in Pediatrics: A Case Series

Lactococcus spp. is typically thought to be of low virulence and seldom considered pathogenic. Few cases of significant infections in children have been reported, all outside of the United States. There is also limited data on antimicrobial susceptibility testing for Lactococcus spp. We present three pediatric patients with central line bloodstream infections due to Lactococcus spp. between 2018 and 2020, along with a review of the pediatric literature.

Lactococcus lactis bacteraemia in a patient on probiotic supplementation therapy

A 59-year-old woman presented with fever and malaise and was found to have Lactococcus lactis bacteraemia. L. lactis infection is rare in humans with few reported cases, with most associated with dairy food product ingestion. The patient reported use of a multistrain over-the-counter probiotic supplement. After isolation of L. lactis from blood culture, the patient was treated empirically with ertapenem and amoxicillin and displayed clinical improvement. She remained well after completion of antibiotic regimen and discontinued probiotic supplementation use. We review the clinical presentation of L. lactis infection including diagnosis, identification and treatment.

Lactococcus lactis cholangitis and bacteremia identified by MALDI-TOF mass spectrometry: A case report and review of the literature on Lactococcus lactis infection

Lactococcus lactis is a rare causative organism in humans. Cases of L. lactis infection have only rarely been reported. However, because it is often difficult to identify by conventional commercially available methods, its incidence may be underestimated. We herein report the case of a 70-year-old man with cholangiocarcinoma who developed L. lactis cholangitis and review previously reported cases of L. lactis infection. Our case was confirmed by matrix-assisted desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). This case shows L. lactis is a potential causative pathogen of cholangitis and that MALDI-TOF MS can be useful for the rapid and accurate identification of L. lactis infection. We searched the literature for published case reports on cholangitis and any other infections caused by L. lactis, and thereby identified 36 cases, including our case. At least 66.7% (n = 24) of the cases had significant underlying conditions; 15 of the cases involved patients with an immunocompromised status. At least 41.7% (n = 15) had a significant food consumption history, such as the consumption of unpasteurized dairy products. The clinical sources of L. lactis were diverse and endocarditis was the most common diagnosis (n = 8), followed by hepatobiliary infection (n = 6), central nervous system infection (n = 5), and peritonitis (n = 4). The prognosis was favorable in most cases.

A Case of Infective Endocarditis and Pulmonary Septic Emboli Caused by Lactococcus lactis

Infective endocarditis is a rare condition in children with normal hearts. We present here a case of previously healthy eleven-year-old girl with infective endocarditis and pulmonary septic emboli caused by a very rare bacterial etiology (Lactococcus lactis). Identification of this pathogen was only made by polymerase chain reaction.

Lactococcus lactis Catherter-Related Bloodstream Infection in an Infant: Case Report

Lactococcus lactis is a gram-positive coccus that is nonpathogenic in humans. Herein, we present the case of a 1-year-old boy with Down syndrome and Hirschprung's disease (HD) who developed a catheter-related bloodstream infection with L. lactis after gastrointestinal surgery. The patient had been hospitalized in the pediatric surgery unit from birth because of HD, and had undergone the Duhamel-Martin procedure which caused recurrent diarrhea episodes and feeding intolerance. On the infant's 430th day of life, he had an episode of gastroenteritis and feeding intolerance. Because of clinical suspiction of sepsis, blood cultures were taken both from the central venous catheter and peripheral vein, and evidence of a growing microorganism was detected in 2 different central venous catheter blood cultures taken 2 days apart. The colonies were then identified by both the Vitek 2 and Vitek MS systems (bioMérieux, Marseille, France) as L. lactis spp. lactis. The central venous catheter could not be removed because of the absence of a peripheral venous line, and the patient was subsequently successfully treated with vancomycin. Therefore, although Lactococcus species is generally thought to be nonpathogenic, it should still be kept in mind as a potential pathogen in infants.

Matrix-assisted laser desorption ionization-time of flight mass spectrometry: a fundamental shift in the routine practice of clinical microbiology

Within the past decade, clinical microbiology laboratories experienced revolutionary changes in the way in which microorganisms are identified, moving away from slow, traditional microbial identification algorithms toward rapid molecular methods and mass spectrometry (MS). Historically, MS was clinically utilized as a high-complexity method adapted for protein-centered analysis of samples in chemistry and hematology laboratories. Today, matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) MS is adapted for use in microbiology laboratories, where it serves as a paradigm-shifting, rapid, and robust method for accurate microbial identification. Multiple instrument platforms, marketed by well-established manufacturers, are beginning to displace automated phenotypic identification instruments and in some cases genetic sequence-based identification practices. This review summarizes the current position of MALDI-TOF MS in clinical research and in diagnostic clinical microbiology laboratories and serves as a primer to examine the "nuts and bolts" of MALDI-TOF MS, highlighting research associated with sample preparation, spectral analysis, and accuracy. Currently available MALDI-TOF MS hardware and software platforms that support the use of MALDI-TOF with direct and precultured specimens and integration of the technology into the laboratory workflow are also discussed. Finally, this review closes with a prospective view of the future of MALDI-TOF MS in the clinical microbiology laboratory to accelerate diagnosis and microbial identification to improve patient care.

Murine gut microbiota and transcriptome are diet dependent

OBJECTIVE

Here, we determine how formula feeding impacts the gut microbiota and host transcriptome.

BACKGROUND

Formula-fed (FF) infants are at risk for diseases that involve complex interactions between microbes and host immune elements such as necrotizing enterocolitis. The aims of this study were to simultaneously examine the microbiota and host transcriptional profiles of FF and maternal-fed (MF) mice to evaluate how diet impacts gut colonization and host genes.

METHODS

After 72 hours of FF or MF, colonic tissue was collected. 16S ribosomal RNA was sequenced with Roche GS-FLX (Genome Sequencer-FLX) pyrosequencing. Operational taxonomical unit clustering, diversity analysis, and principal coordinate analysis (PCA) were performed. Complementary DNA libraries were sequenced by Solexa. Reads were annotated by BLAST (Basic Local Alignment Search Tool) search against mouse RNA database [National Center for Biotechnology Information (NCBI) build-37] and functionally classified using the KOG (Eukaryotic Orthologous Groups) database (NCBI).

RESULTS

Firmicutes (P < 0.001) was the dominant phylum in MF pups, whereas Proteobacteria (P < 0.001) and Bacteroidetes (P < 0.05) were dominant in FF mice. On the genus level, FF mice had increased Serratia (P < 0.001) and Lactococcus (P < 0.05) whereas MF mice had increased Lactobacillus (P < 0.001). PCA confirmed clustering by diet. Solexa sequencing demonstrated different (P < 0.05) messenger RNA transcript levels in 148 genes. Heme oxygenase 1 (P < 0.01), an oxidative stress marker, was increased 25-fold in FF mice. In addition, decreased vinculin (P < 0.05), a cytoskeletal protein associated with adherens junctions in FF pups suggested impaired gut structural integrity. Diet also impacted immune regulation, cell cycle control/gene expression, cell motility, and vascular function genes.

CONCLUSIONS

FF shifted gut microbiota and structural integrity, oxidative stress, and immune function genes, presumably increasing vulnerability to disease in FF mice. Interrogation of microbial and host gene expression in FF neonates may offer new insight on how diet affects disease pathogenesis.