The reactive oxygen species-induced small RNA CsrO promotes the survival of Cronobacter sakazakii in macrophages and systemic infection within the host.

Cronobacter sakazakii is a foodborne pathogen linked to severe infections in infants and often associated with contaminated powdered infant formula. The RecA protein, a key player in DNA repair and recombination, also influences bacterial resilience and virulence. This study investigated the impact of recA deletion on the pathogenicity and environmental stress tolerance of C. sakazakii BAA-894. A recA knockout mutant displayed impaired growth, desiccation tolerance, and biofilm formation. In a rat model, the mutant demonstrated significantly reduced virulence evidenced by higher host survival rates and lower bacterial loads in blood and tissues compared to the wild-type strain. Proteomic analysis revealed extensive disruptions in protein expression, particularly downregulation of carbohydrate metabolism and respiration-related proteins, alongside increased protein deamidation and oxidation. Functional assays identified fructose-bisphosphate aldolase as a target of oxidative and deamidative damage, resulting in reduced enzymatic activity and glycolytic disruption. These findings highlight the critical role of RecA in maintaining protein homeostasis, environmental resilience, and pathogenicity in C. sakazakii, providing valuable insights for developing targeted interventions against this pathogen.IMPORTANCECronobacter sakazakii poses significant risks due to its ability to persist in low-moisture environments and cause severe neonatal infections. This study identifies RecA as a key factor in environmental resilience and virulence, making it a promising target for mitigating infections and contamination. Inhibiting RecA function could sensitize C. sakazakii to stress during production and sterilization processes, reducing its persistence in powdered infant formula. Future research on RecA-specific inhibitors may lead to innovative strategies for enhancing food safety and preventing infections caused by this pathogen.

Cronobacter sakazakii is an opportunistic pathogen that causes severe infections in neonates and infants through contaminated powdered infant formula (PIF). Therefore, the aim of this study was a large-scale study on determine the prevalence, molecular characterization and antibiotic susceptibility of C. sakazakii isolates from PIF purchased from Chinese retail markets. Two thousand and twenty PIF samples were collected from different institutions. Fifty-six C. sakazakii strains were isolated, and identified using fusA sequencing analysis, giving a contamination rate of 2.8%. Multilocus sequence typing (MLST) was more discriminatory than other genotyping methods. The C. sakazakii isolates were divided into 14 sequence types (STs) by MLST, compared with only seven clusters by ompA and rpoB sequence analysis, and four C. sakazakii serotypes by PCR-based O-antigen serotyping. C. sakazakii ST4 (19/56, 33.9%), ST1 (12/56, 21.4%), and ST64 (11/56, 16.1%) were the dominant sequence types isolated. C. sakazakii serotype O2 (34/56, 60.7%) was the primary serotype, along with ompA6 and rpoB1 as the main allele profiles, respectively. Antibiotic susceptibility testing indicated that all C. sakazakii isolates were susceptible to ampicillin-sulbactam, cefotaxime, ciprofloxacin, meropenem, tetracycline, piperacillin-tazobactam, and trimethoprim-sulfamethoxazole. The majority of C. sakazakii strains were susceptible to chloramphenicol and gentamicin (87.5 and 92.9%, respectively). In contrast, 55.4% C. sakazakii strains were resistant to cephalothin. In conclusion, this large-scale study revealed the prevalence and characteristics of C. sakazakii from PIF in Chinese retail markets, demonstrating a potential risk for neonates and infants, and provide a guided to effective control the contamination of C. sakazakii in production process.

Short communication: Effects of vacuum freeze-drying on inactivation of Cronobacter sakazakii ATCC29544 in liquid media with different initial inoculum levels

Cronobacter spp is an opportunistic pathogen that can cause severe neonatal infections, including septicemia, meningitis, and necrotizing enterocolitis. Over 90% of these infections outbreaks are associated with the increased consumption of powdered infant formula (PIF). We report the case of a male neonate born at term with adequate weight for gestational age, fed by breast milk and PIF. He was admitted to the ICU at 22 days old due to fever, irritability, impaired consciousness, and food intolerance. Investigation revealed an extensive abscess in the right frontoparietal region, that was surgically drained. The culture of the purulent material showed the growth of Cronobacter spp. Guided antibiotic was kept for 21 days. The patient presented a good clinical outcome, without neurological deficits. The microbiological powdered formula contamination by Enterobacter sakazakii (Cronobacter spp) can lead to a higher risk of severe infections in infants. Children may present sepsis, sensory alteration, and refractory seizures. An early brain image should be considered for symptomatic infants. The mortality rate ranges from 40 to 80%, and 74% of survivors have an adverse neurological outcome. From 1997–2013, there were reports of 6 outbreaks of E. sakazakii disease in Brazil. According to the World Health Organization (WHO), this disease is undernotified, and active foodborne surveillance systems are less than ideal. To better address this problem, in some countries, the notification is mandatory, and the adoption of stricter sanitary measures by regulatory agencies are proposed.

Genotypic and phenotypic characteristics of group B streptococcal isolates from neonates in a tertiary hospital in Qingyang, Gansu Province, China.

Cronobacter sakazakii can cause severe life-threatening invasive infections in neonates, with a high mortality rate mostly associated with powdered infant formula consumption. The study describes a fatal C. sakazakii infection in premature infant fed only with expressed human milk. Despite the identification of etiological factor from patient’s blood, the epidemiological investigation, including mother’s skin, hospital surfaces, milk expressing devices, and milk samples, did not show bacterial contamination. The infection was caused by C. sakazakii ST1, being one of the leading genotypes reported in invasive infections. The phylogenetic analysis of the international collection of the ST1 organisms allowed us to identify the isolate as a member of the main cluster. The pathogenic potential of the isolate was augmented by the presence of IncFIB-like molecule representing virulence plasmids of pESA-3 family. Isolate presented ESBL phenotype associated with blaSHV-12 gene harboured by IncX3 plasmid. The described case gave valuable information to genetics of Cronobacter, and also urges the need of wider whole-genome sequencing implementation as a part of diagnostic procedure.

Cronobacter sakazakii causes severe neonatal infections, but we know little about gut carriage of this pathogen in very low birthweight infants. We sequenced 16S ribosomal RNA (rRNA) genes from 2304 stools from 121 children at St Louis Children's Hospital whose birthweight was ≤1500 g, attempted to isolate C. sakazakii from 157 of these stools, genome-sequenced the recovered isolates, and sought correlations between indices of Cronobacter excretion, host characteristics, and unit formula use. Of these 2304 stools, 1271 (55.2%) contained Cronobacter rRNA gene sequences. The median (interquartile range) per-subject percentage of specimens with at least 1 Cronobacter sequence and the median per-subject read density were 57.1 (25.5-87.3) and 0.07 (0.01-0.67), respectively. There was no variation according to commercially prepared liquid vs powdered formula use in the neonatal intensive care unit, or the day of life that specimens were produced. However, the proportion of specimens containing >4.0% of reads mapping to Cronobacter fell from 4.3% to 0.9% after powdered infant formula was discontinued (P < .0001). We isolated sequence type 4 (ST4) C. sakazakii from multiple specimens from 2 subjects; 1 also harbored sequence type 233. The sequenced ST4 isolates from the 2 subjects had >99.9% sequence identity in the approximately 93% of best-match reference genome that they contained, and shared multiple virulence loci. Very low birthweight infants excrete putatively pathogenic Cronobacter. High-density Cronobacter sequence samples were more common during the use of powdered infant formula. Better understanding of the ecology of Cronobacter in infant guts will inform future prevention and control strategies.

Potential factors involved in virulence of Cronobacter sakazakii isolates by comparative transcriptome analysis

Cronobacter sakazakii is a Gram-negative bacterium known for causing severe infections in neonates, particularly through contaminated infant formula. This study investigated the role of the outer membrane lipoprotein NlpD in the environmental tolerance of C. sakazakii. A nlpD knockout mutant was constructed, and its impact on desiccation resistance, biofilm formation, motility, and proteomic profiles was evaluated and compared with that of the wild-type strain. The nlpD mutant presented reduced desiccation tolerance, reduced ability to form a biofilm, and altered surface hydrophobicity and motility patterns. The complemented strain restored these phenotypic changes, confirming that the observed effects were specifically due to the deletion of nlpD. Proteomic analysis revealed significant differential expression of proteins involved in metabolic and biosynthetic pathways upon nlpD deletion. These findings emphasize the multifaceted role of NlpD in enhancing the environmental tolerance of C. sakazakii, suggesting its importance in the resilience and survival of the bacterium in adverse conditions.

Impact of pmrA on Cronobacter sakazakii planktonic and biofilm cells: A comprehensive transcriptomic study

First clinical isolates of Cronobacter spp. (Enterobacter sakazakii) in Argentina: Characterization and subtyping by pulsed-field gel electrophoresis

Short communication: Roles of outer membrane protein W on survival, cellular morphology, and biofilm formation of Cronobacter sakazakii in response to oxidative stress

Franconibacter (Enterobacter, Cronobacter) pulveris bacteria share several typical characteristics with, and hence pose a challenge for the detection of, Cronobacter sakazakii, an emerging opportunistic pathogen, which can cause severe infections in neonates. A structurally variable O-specific polysaccharide (OPS) called O antigen provides the major basis for the typing of Gram-negative bacteria. We investigated the structure and genetics of the O antigen of F. pulveris G3872 (designated O1). An OPS was isolated by mild alkaline degradation of the LPS, whereas the same polysaccharide and its oligosaccharide fragments were obtained by mild acid degradation. Studies by sugar analysis and NMR spectroscopy showed that the OPS contained d-ribose, l-rhamnose (l-Rha) and a rarely occurring monosaccharide 4-deoxy-d-arabino-hexose, and the OPS structure was established. The O-antigen gene cluster of F. pulveris G3872 between JUMPStart and gnd genes includes putative genes for glycosyltransferases, ATP-binding cassette (ABC)-transporter genes wzm and wzt, and genes for the synthesis of l-Rha, but no genes for the synthesis of 4-deoxy-d-arabino-hexose. A mutation test with the wzm gene confirmed that the OPS is synthesized and exported by the ABC-transporter-dependent pathway. A trifunctional transferase was suggested to catalyse formation of two glycosidic linkages and add a methyl group to the non-reducing end of the OPS to terminate the chain elongation. A carbohydrate-binding module that presumably recognizes the terminal methyl-modified monosaccharide was found at the C-terminus of Wzt. Primers specific for F. pulveris G3872 were designed based on the wzm gene, which has potential to be used for identification and detection of the O1 serogroup.

Outbreak of colonization of neonates with Enterobacter sakazakii

Described by the Brazilian scientist Carlos Chagas more than a century ago, Chagas disease (ChD) currently affects 8 to 10 million persons and causes more than 10 000 deaths each year.[1][1] Originally confined to Latin American countries, ChD had been considered an exotic disease and received less