Neonatal sepsis-causing bacterial pathogens and outcome of trends of their antimicrobial susceptibility a 20-year period at a neonatal intensive care unit

Pathogenic characterization and drug resistance of neonatal sepsis in China: a systematic review and meta-analysis

OBJECTIVES

Neonatal sepsis is one of the causes of neonatal mortality and bacterial resistance to antibiotics is one of the challenges facing NICU. The aim of this study was to provide a basis for empirical antibiotic selection by comprehensively searching Chinese and non-Chinese databases for studies related to neonatal sepsis pathogenesis conducted in China and synthesizing all the results of the studies conducted in hospitals in China during the period under study METHODS: In this study, we conducted extensive searches of Pubmed, Web of Science, Cochrane, China Biology Medicine disc (SinoMed), China National Knowledge Infrastructure (CNKI) and Wanfang Data. We screened studies published from 2014 to 2023 that were conducted in hospitals in mainland China and involved bacterial blood cultures and susceptibility tests in neonates with neonatal sepsis and extracted the data, which were summarized using Stata 18.0 software to determine the bacterial characteristics of NS and its antimicrobial resistance in China.

RESULTS

A total of 97 articles were finally included in the study, involving 27 provinces, municipalities and autonomous regions, and a total of 18,796 bacterial strains were isolated. Among them, Gram-positive bacteria (G+) accounted for 63.4% (95% CI 59.6%~67.3% ), and Gram-negative bacteria (G-) accounted for 36.6% (95% CI 32.7%~40.4%). The most common bacteria were, in order, Coagulase-negative Staphylococcus (43.6%, 95% CI 37.9-49.3%), Enterobacter (16.4%, 95% CI 14.8-18.1%), and Klebsiella (12.4%, 95% CI 10.8-14.0%). More than 80% of G + were resistant to penicillin, ampicillin, and benzathine, and no strains resistant to minocycline or daptomycin were found. More than 80% of G- were resistant to benzoxicillin, ampicillin, and cefotaxime, and no strains resistant to vancomycin, clindamycin, tigecycline, teicoplanin, and linezolid were identified.

CONCLUSION

Coagulase-negative Staphylococcus is still the main causative agent for children with neonatal sepsis in China, followed by Enterobacter and Klebsiella. In addition, Group B Streptococcus is no longer in the top three common causative agents. Resistance to penicillin antibiotics is evident among the causative organisms of neonatal sepsis in China.

A 10-Year Study of Neonatal Sepsis from Tuen Mun Hospital, Hong Kong

BACKGROUND

Neonatal sepsis is a major cause of infant mortality, and it accounts for a significant consumption of antimicrobials in paediatrics. This is the first comprehensive study on neonatal sepsis in Hong Kong.

METHODS

From 2014 to 2023, all neonates admitted to a single institution with culture-proven infections from the blood and/or cerebrospinal fluid were selected and reviewed retrospectively. The infecting organisms, their antibiotic nonsusceptibility pattern, and the concordance of empirical antimicrobial therapy with the microbiological profiles were described and were further compared between infants of normal/low birth weight (≥1.5 kg) and very low/extremely low birth weight (<1.5 kg), early-onset sepsis (<72 h), and late-onset sepsis (4-28 days), the first and the second 5-year periods (2014-2018 vs. 2019-2023).

RESULTS

After contaminants were excluded, there were 118 affected neonates with 125 organisms identified. Fifty-nine were male. Thirty-four were very low/extremely low birth weight infants, and twenty-eight infants had early-onset sepsis. Patient demographics and the microbiology findings did not differ between the first 5 years and the latter 5 years. However, the incidence of neonatal sepsis was significantly lower in the latter 5 years (3.23 vs. 1.61 per 1000 live births, p < 0.001), the period that coincided with the COVID-19 pandemic. Escherichia coli was the most common Gram-negative pathogen. Streptococcus agalactiae and Streptococcus bovis group infections were more common in early-onset sepsis, while coagulase-negative Staphylococcus and non-E. coli Gram-negative pathogens were more likely to occur in late-onset sepsis. In very low/extremely low birth weight infants, the rate of cefotaxime or ceftriaxone nonsusceptibility among Gram-negative isolates was higher (p = 0.01), and concordance of empirical antimicrobial therapy was lower (p = 0.006).

CONCLUSIONS

Management of neonatal sepsis remains challenging, and there is a need for optimising antimicrobial therapy, especially in preterm patients. Antepartum screening with intrapartum antibiotic prophylaxis is effective in reducing the risk of early-onset sepsis associated with S. agalactiae, while stringent infection control measures are important for the prevention of late-onset sepsis.

Oxacillin-resistant Staphylococcus spp.: Impacts on fatality in a NICU in Brazil - confronting the perfect storm

OBJECTIVE

Analyse the incidence, risk factors, antimicrobial susceptibility profile, and fatality in neonates infected with oxacillin-resistant Staphylococcus spp. (ORS).

METHODS

In this retrospective observational descriptive cohort study, the medical records of neonates admitted to the Neonatal Intensive Care Unit (NICU) from January 2015 to June 2022 were analysed. Participants were monitored daily through the National Healthcare Safety Network.

RESULTS

Among the 1610 neonates, 193 (12 %) developed ORS infections, primarily in the bloodstream (96.8 %). The incidence of these infections/patient-days decreased by 51.8 % between 2016 (8.3) and 2022 (4). The median age of affected neonates was 17.5 days (IQR:12-28.7). Pre-emptive prescription of fourth-generation cephalosporins (OR=14.36; P<0.01) emerged as a risk factor in the multivariate analysis. Staphylococcus epidermidis was the most prevalent species (60.1 %), with one isolate showing a "susceptible, increased exposure" profile to vancomycin. Additionally, 2 % of pathogens were extensively drug-resistant (XDR). ORS infections were associated with prolonged hospital stays (from 10 to 46 days) and increased mortality (from 10.2 % to 19.2 %). The median time between infection and the fatal outcome was 15 days (IQR:8-40), and Staphylococcus capitis was the most lethal species (26.7 %).

CONCLUSIONS

The high incidence of ORS infections was linked to extended hospitalisation and increased mortality, highlighting the complexity of this situation - a "perfect storm." This underscores the urgency of implementing effective interventions for managing and preventing ORS infections in the NICU.

Bloodstream Infections in the Neonatal Intensive Care Unit: A Systematic Review of the Literature

Bloodstream infections represent a significant concern in neonatal intensive care units (NICUs), constituting a leading cause of morbidity and mortality among neonates. This study aimed to elucidate the etiology, prevalence, and antimicrobial resistance patterns of bloodstream infections in NICU settings. A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement guidelines using the PubMed database to source relevant studies published between 2019 and 2023. Keywords related to bloodstream infections, neonates in NICUs, pathogens, resistance, and susceptibility were employed. Out of the 73 identified articles, eight met the inclusion criteria. Findings revealed a predominance of late-onset sepsis in hospitalized neonates, with Escherichia coli, Klebsiella pneumoniae, coagulase-negative staphylococci, Group B Streptococcus, Acinetobacter species, Serratia marcescens, Staphylococcus aureus, and Enterobacter cloacae being the most commonly isolated pathogens. Antimicrobial susceptibility profiles demonstrated resistance among bacteria to ampicillin, gentamicin, and penicillin, while fungi exhibited resistance to amphotericin B, fluconazole, flucytosine, itraconazole, and voriconazole. These findings underscore the persistent challenge of bloodstream infections in the NICUs, particularly late-onset sepsis, emphasizing the importance of early detection and appropriate antimicrobial therapy in neonatal care management.

Loop-mediated isothermal amplification (LAMP) assay for early on-site detection of Group B Streptococcus infection in neonatal sepsis blood sample

BACKGROUND

Neonatal sepsis, often attributed to Group B Streptococcus (GBS) infection, poses a critical health risk to infants, demanding rapid and accurate diagnostic approaches. Existing diagnostic approaches are dependent on traditional culture methods, a process that requires substantial time and has the potential to delay crucial therapeutic assessments.

METHODS

This study introduces an innovative Loop-Mediated Isothermal Amplification (LAMP) assay for the early on-site detection of GBS infection from neonatal sepsis blood samples. To develop a LAMP assay, the primers are designed for the selective targeting of a highly conserved segment within the cfb gene encoding the CAMP factor in Streptococcus agalactiae ensuring high specificity.

RESULTS

Rigorous optimization of reaction conditions, including temperature and incubation time, enhances the efficiency of the LAMP assay, enabling rapid and reliable GBS detection within a short timeframe. The diagnostic efficacy of the LAMP assay was evaluated using spiked blood samples by eliminating the DNA extraction step. The simplified colorimetric LAMP assay has the capability to detect S. agalactiae in a neonatal blood sample containing 2 CFU/mL during sepsis. Additionally, the LAMP assay effectively detected S. agalactiae in both the standard and spiked blood samples, with no detectable interference with blood.

CONCLUSION

This optimised LAMP assay emerges as a promising tool for early GBS detection, offering a rapid and accurate on-site solution that has the potential to inform timely interventions and improve outcomes in neonatal sepsis cases.

Trends in Causative Organisms and Antimicrobial Resistance in Late-onset Neonatal Sepsis

The aim of this study was to evaluate the antibiotic resistance of microorganisms isolated in cases of culture-positive nosocomial late-onset neonatal sepsis in the neonatal intensive care unit. Infants admitted to our neonatal intensive care unit between October 2015 and June 2022 were retrospectively screened. A total of 458 different cultures from 386 sepsis incidents in 250 infants were analyzed. Over an 8-year period, 407 cases of culture-positive nosocomial late-onset neonatal sepsis were reviewed in a total of 4244 infants. Twenty-one cases were excluded due to insufficient data. The incidence of culture-positive nosocomial sepsis was 6.3%. Coagulase-negative Staphylococcus and Staphylococcus aureus were the most common gram-positive bacteria found in cultures. Resistance to ampicillin and cephalosporin treatments was high, while resistance to vancomycin, teicoplanin, and linezolid was low. Klebsiella spp. were the most frequent gram-negative bacteria isolated in cultures and showed high resistance to non-carbapenembased regimens. The only fungal microorganisms isolated in cultures were Candida spp., which had a high mortality rate despite their low resistance profile. The mortality rate due to nosocomial sepsis was 19.6%. Our study demonstrated that microorganisms and their antibiotic resistance profiles changed over time in the newborn intensive care unit. Gram-negative pathogens exhibited high antibiotic resistance, while fungi had high mortality rates. It is essential to adjust empirical antibiotic regimens for nosocomial sepsis based on thorough surveillance.

A decade of neonatal sepsis in Stockholm, Sweden: Gram-positive pathogens were four times as common as Gram-negatives

PURPOSE

To assess Gram-positive bacterial (GPB) bloodstream infection (BSI) in neonates, covering incidence, morbidity, mortality, antimicrobial resistance patterns and biomarkers in Region Stockholm, Sweden between 2006 and 2016.

METHODS

A population-based retrospective epidemiological study including infants with GPB-BSI, admitted to the neonatal units at Karolinska University Hospital (KUH). Data were collected from patient records, the Swedish Neonatal Quality Register, the microbiological laboratory at KUH and the Swedish Public Health Agency.

RESULTS

We identified 357 infants with GPB-BSI, representing an incidence of 1.47/1000 live births (LB). Group B streptococcus (GBS) was the most common pathogen causing BSI in full-term infants and early-onset sepsis (EOS) (0.20/1000 LB), while coagulase-negative staphylococci (CoNS) were predominant in infants born very preterm and in late-onset sepsis (LOS) (0.79/1000 LB). There were no fatal GBS BSI cases, but 10.2% developed meningitis. The GPB case fatality rate was 9.5% and the sepsis fatality rate 2.8%. In GPB-BSI, 1/10 did not have an elevated C-reactive protein level. Staphylococcus aureus (S. aureus) BSI increased during the study period, but no methicillin or vancomycin resistant strains were found. The antimicrobial resistance (AMR) rate was highest in CoNS isolates.

CONCLUSION

GPB-BSI was four times more common than Gram-negative BSI in neonates but resulted in lower mortality rate. GBS was the most common pathogen in full-term infants and in EOS. CoNS was the most common pathogen in LOS and infants born very preterm, and the AMR rate was high in these isolates. The increasing trend of S. aureus BSI indicates a need of further investigation.

Improving Activity of New Arylurea Agents against Multidrug-Resistant and Biofilm-Producing Staphylococcus epidermidis

Multidrug-resistant (MDR) strains of Staphylococcus epidermidis (S. epidermidis), prevalent in hospital environments, contribute to increased morbidity and mortality, especially among newborns, posing a critical concern for neonatal sepsis. In response to the pressing demand for novel antibacterial therapies, we present findings from synthetic chemistry and structure-activity relationship studies focused on arylsulfonamide/arylurea derivatives of aryloxy[1-(thien-2-yl)propyl]piperidines. Through bioisosteric replacement of the sulfonamide fragment with a urea moiety, compound 25 was identified, demonstrating potent bacteriostatic activity against clinical multidrug-resistant S. epidermidis strains (MIC50 and MIC90 = 1.6 and 3.125 μg/mL). Importantly, it showed activity against linezolid-resistant strains and exhibited selectivity over mammalian cells. Compound 25 displayed antibiofilm-forming properties against clinical S. epidermidis strains and demonstrated the capacity to eliminate existing biofilm layers. Additionally, it induced complete depolarization of the bacterial membrane in clinical S. epidermidis strains. In light of these findings, targeting bacterial cell membranes with compound 25 emerges as a promising strategy in the fight against multidrug-resistant S. epidermidis strains.

Incidence, pathogens and antimicrobial resistance of blood and cerebrospinal fluid isolates from a tertiary neonatal unit in South Africa: A 10 year retrospective review

OBJECTIVE

To determine trends in incidence, etiology and antimicrobial susceptibility of blood and cerebrospinal fluid (CSF) culture confirmed infections in hospitalized infants in a large tertiary neonatal unit in South Africa.

METHODS

Single-center, retrospective review of laboratory records of bacteria and fungi, and their susceptibility profiles, isolated from blood and CSF of infants hospitalized in the neonatal unit at Chris Hani Baragwanath Academic Hospital, Johannesburg, South Africa, from 1st January 2010 to 31st December 2019. Laboratory data on isolates and their antimicrobial susceptibilities were collected. Coagulase-negative Staphylococcus, Corynebacteria and Bacillus spp. were excluded. Patient-level clinical and laboratory data were not available.

RESULTS

There were 8,319 significant isolates, giving an infection rate of 14.3/1000 patient-days. Infection rates increased from 12.0 to 15.7/1000 patient-days (estimated average yearly change 0.6[95%CI, 0.5-0.7];p = <0.001). Gram-negative infection rates increased from 4.3 to 10.8/1000 patient-days (estimated average yearly change 0.7[95%CI,0.6-0.8];p = <0.001). The 2 most commonly isolated Gram-negative organisms were Acinetobacter baumannii (44%) and Klebsiella pneumoniae (39%). Carbapenem resistance was seen in 31% of all Gram-negatives and increased over time (estimated average yearly change 4.8%[95%CI,4.2%-5.3%];p<0.001). Gram-positive infection rates decreased (estimated average yearly change -0.1[95%CI,-0.2- -0.05];p = <0.001). Staphylococcus aureus was the most common Gram-positive isolated. Rates of methicillin-resistant Staphylococcus aureus decreased from 91% to 55%(estimated average yearly change -2.8%[95%CI,-3.5%-2%],p< 0.001). Rates of fungal isolates decreased (estimated average yearly change -0.06[95%CI,-0.1 --0.02]);p = 0.007). Candida parapsilosis (52%) and Candida albicans (35%) were the most common fungi isolated.

CONCLUSIONS

There has been a marked overall increase in rates of blood and/or CSF infections, with an absolute increase in Gram-negative infections observed, replacing Gram-positive and fungal pathogens. Extended spectrum beta-lactamase Gram-negative isolates are being replaced by carbapenem resistance, with around one third of all significant Gram-negative isolates now carbapenem resistant. Research into hospital based novel treatment and prevention interventions for neonatal sepsis should be urgently prioritized.

New Insights in Immunometabolism in Neonatal Monocytes and Macrophages in Health and Disease

It is well established that the neonatal immune system is different from the adult immune system. A major task of the neonatal immune system is to bridge the achievement of tolerance towards harmless antigens and commensal bacteria while providing protection against pathogens. This is highly important because neonates are immunologically challenged directly after birth by a rigorous change from a semi-allogeneic sterile environment into a world rich with microbes. A so called disease tolerogenic state is typical for neonates and is anticipated to prevent immunopathological damage potentially at the cost of uncontrolled pathogen proliferation. As a consequence, neonates are more susceptible than adults to life-threatening infections. At the basis of a well-functioning immune response, both for adults and neonates, innate immune cells such as monocytes and monocyte-derived macrophages play an essential role. A well-responsive monocyte will alter its cellular metabolism to subsequently induce certain immune effector function, a process which is called immunometabolism. Immunometabolism has received extensive attention in the last decade; however, it has not been broadly studied in neonates. This review focuses on carbohydrate metabolism in monocytes and macrophages in neonates. We will exhibit pathways involving glycolysis, the tricarboxylic acid (TCA) cycle and oxidative phosphorylation and their role in shaping neonates' immune systems to a favorable tolerogenic state. More insight into these pathways will elucidate potential treatments targets in life-threatening conditions including neonatal sepsis or expose potential targets which can be used to induce tolerance in conditions where tolerance is harmfully impaired such as in autoimmune diseases.

Anti-tuberculosis treatment strategies and drug development: challenges and priorities

Despite two decades of intensified research to understand and cure tuberculosis disease, biological uncertainties remain and hamper progress. However, owing to collaborative initiatives including academia, the pharmaceutical industry and non-for-profit organizations, the drug candidate pipeline is promising. This exceptional success comes with the inherent challenge of prioritizing multidrug regimens for clinical trials and revamping trial designs to accelerate regimen development and capitalize on drug discovery breakthroughs. Most wanted are markers of progression from latent infection to active pulmonary disease, markers of drug response and predictors of relapse, in vitro tools to uncover synergies that translate clinically and animal models to reliably assess the treatment shortening potential of new regimens. In this Review, we highlight the benefits and challenges of 'one-size-fits-all' regimens and treatment duration versus individualized therapy based on disease severity and host and pathogen characteristics, considering scientific and operational perspectives.

Mortality Risk Factors of Early Neonatal Sepsis During COVID-19 Pandemic

Purpose

This study aimed to determine predisposing factors for negative outcome in infants with early neonatal sepsis during COVID-19.

Patients and Methods

A prospective cohort study of 172 newborns up to 4 days diagnosed with neonatal sepsis was carried out in Karaganda (Kazakhstan). The microbiological examination was used to identify a causative agent of bloodstream infection. ELISA was performed to determine the total anti-SARS-CoV-2 antibodies. Gestational age, mode of delivery, birth weight, C-reactive protein and procalcitonin levels, comorbidities, type of pathogen, duration of hospitalization and mother’s infection diseases were used for statistical analysis.

Results

Mortality in infants with neonatal sepsis was 22% (38/172). Anti-SARS-CoV-2 antibodies were detected in 68.3% of the newborns. Culture-negative ELBW infants have a 5.3-fold higher risk of death (p<0.001). Low gestational age and a shorter period of hospitalization were statistically associated with fatality. CRP is generally higher in deceased children (p=0.002). Necrotizing enterocolitis (p<0.001), pneumonia (p=0.009) and anemia (p=0.016) were significantly associated with negative outcome. And, 31.4% of the infants with sepsis had positive blood cultures. The leading cause of sepsis in newborns was CoNS – 57%.

Conclusion

During COVID-19 pandemic neonatal sepsis mortality was associated with low birth weight, gestational age, and comorbidities as in non-pandemic time. The relationship between COVID-19 in the mother and neonatal mortality was not found. However, anti-SARS-CoV-2 antibodies were detected in more than half of newborns.

Clinical Laboratory Features of Microbes That Cause Neonatal Sepsis: An 8-Year Retrospective Study

Purpose

To determine the distribution and antibiotic resistance patterns among pathogens that cause neonatal sepsis (NS) and to assess trends in antibiotic resistance.

Patients and methods

A total of 864 patients with sepsis admitted to a neonatal intensive care unit (NICU) between 2014 and 2021 were enrolled. Data on neonate age and sex, pathogenic microbes, and antimicrobial susceptibility were collected. Univariate and linear regression analyses were performed to determine the differences and trends in antibiotic resistance rates.

Results

The overall incidence rate of NS was 4.59 cases per 1000 live births. Of these cases, 255 (29.5%) were early-onset neonatal sepsis (EONS) and 609 (70.5%) were late-onset neonatal sepsis (LONS). A total of 670 (70.5%) gram-positive cocci and 171 (19.8%) gram-negative bacilli were identified. Among the 552 coagulase-negative Staphylococcus (CoNS) strains, the rate of oxacillin resistance was 70.6%, but no strains were resistant to linezolid, vancomycin or tigecycline. Among the antibiotic resistance patterns of the top three gram-negative pathogens, K. pneumoniae showed the highest rates of resistance, with resistance rates of 37.9% and 39.4% to ertapenem and imipenem, respectively, while E. coli and Enterobacter cloacae showed high levels of susceptibility to both. With regard to the trends in resistance among important pathogens, the rates of resistance to rifampicin, ciprofloxacin, levofloxacin, moxifloxacin and clindamycin by Staphylococcus epidermidis significantly decreased (p<0.05) during the study period. E. coli strains exhibited a significant increase in ceftriaxone resistance during the study period (p<0.05).

Conclusion

CoNS was the main microbe that caused NS, followed by E. coli. The bacterial isolates showed varying levels of resistance to the antimicrobial drugs tested. Thus, periodic surveillance in hospital settings to monitor changes in pathogens and antibiotic resistance is important.