Staphylococcal infections in infants: updates and current challenges

Clinical outcomes of Staphylococcus capitis isolation from neonates, England, 2015-2021: a retrospective case-control study

OBJECTIVE

Staphylococcus capitis, a coagulase-negative staphylococci (CoNS) species, has been increasingly detected from UK sterile site samples and has caused neonatal unit outbreaks worldwide. We compared survival to discharge and 30-day mortality for the detection of S. capitis versus other CoNS species.

METHODS

In this retrospective case-control study, we included hospitalised infants with any CoNS species detected from a normally sterile body site up to 90 days of age. We linked English laboratory reports from the Second Generation Surveillance System database, mortality data from the Personal Demographics Service, and neonatal unit admissions from the National Neonatal Research Database. In primary analysis, multivariable logistic regression was used, with two co-primary outcomes: survival to discharge and death within 30 days of positive specimen date. Sensitivity analyses using multiply imputed datasets followed.

RESULTS

We identified 16 636 CoNS episodes relating to 13 745 infants. CoNS episodes were highest among infants born extremely preterm (22-27 weeks) and with extremely low birth weight (400-999 g). In primary analysis, there were no differences in survival to discharge (p=0.71) or 30-day mortality (p=0.77) between CoNS species. In sensitivity analyses, there were no differences in outcomes between infection with four of the most common CoNS species (Staphylococcus epidermidis, S. capitis, Staphylococcus haemolyticus and Staphylococcus warneri) but the remaining CoNS species were at higher risk of adverse outcomes when treated in aggregate.

CONCLUSION

Infants with S. capitis detected from sterile site samples did not experience significant differences in either survival to discharge or 30-day mortality compared with infants with detection of other common CoNS species.

Epidemiology of neonatal sepsis in two neonatal intensive care units in Krakow, Poland in 2016-2017 years

BACKGROUND

Sepsis in low-birth-weight neonates remains one of the most significant causes of neonatal morbidity and mortality. Approximately 3 million newborns suffer from sepsis globally every year. The aim of this study was to compare demographic and clinical features, as well as etiology and antibiotic susceptibility, of the main pathogens related to neonatal sepsis in two neonatal intensive units during a two-year period.

METHODS

We observed early-onset (EO-BSI) and late-onset bloodstream infections (LO-BSI) cases in two high-reference neonatal intensive care units (NICU) over a 24-month period (2016-2017). Samples of patients' blood were tested for the presence of the microorganisms. All bacterial isolates were tested for susceptibility to antibiotics.

RESULTS

The majority of sepsis cases weighed above 1000 g and were born by cesarean section. About 10% of the EO-BSI group died. There were differences in the EO-BSI /LO-BSI ratio in the compared wards due to differences among the admitted children. The most common pathogens isolated from blood were coagulase-negative staphylococci (CoNS) were represented by two dominating species: S. epidermidis and S. haemolyticus, followed by Klebsiella spp. strains and E.coli, which were mostly found in EO-BSI cases. No single S. agalactiae (GBS) strain was isolated. The majority of CoNS strains were resistant to methicillin, half were resistant to aminoglycosides, and one-third were resistant to macrolides and lincosamides. Half of the Gram-negative rods were resistant to beta-lactams.

CONCLUSIONS

The epidemiology of sepsis in two observed NICUs is comparable to data obtained from other studies with a predominance of methicillin-resistant CoNS in LO-BSI and beta-lactam resistant E. coli in EO-BSI. It is of importance that the campaign for controlling GBS carriage in pregnant women in Poland resulted in the disappearance of GBS as a cause of sepsis. Unfortunately, there are no such measures to control E.coli related sepsis.

Reducing Staphylococcus aureus infections in the neonatal intensive care unit

OBJECTIVE

Our neonatal intensive care unit (NICU) saw an increase in Staphylococcus aureus (SA) infections-methicillin-resistant SA (MRSA) infections increased from 2.1/10,000 patient days (PD) to 5.1/10,000 PD, and methicillin-sensitive SA (MSSA) infections from 1.2/10,000 PD to 3.9/10,000 PD. This quality improvement project aimed to decrease the rates of SA infections to less than 2.0/10,000 PD, and to determine the rate of SA decolonization.

METHODS

Infection prevention interventions targeted patient factors (SA surveillance, patient cohorting, decolonization protocol), provider factors (provider cohorting, enhanced hand hygiene) and environmental factors (room structure, equipment optimization).

RESULTS

The rates of MRSA and MSSA infections decreased to 0.6/10,000 PD and 0.7 infections/10,000 PD respectively. Persistent decolonization of SA was successful in 67% of colonized patients.

CONCLUSIONS

Specific interventions targeting patient, provider, and environmental factors, including the implementation of a SA decolonization protocol, were successful in decreasing the incidence of SA infections in neonates.

Prolonged intravenous immunoglobulin treatment in very low birth weight infants with late onset sepsis

BACKGROUND

Neonatal infections are a leading cause of morbi-mortality despite advances in antimicrobials and neonatal care. Preterm infants have greater susceptibility to sepsis due to an immature immune system and lower immunoglobulin levels. Intravenous immunoglobulins (IVIG) have been used in several studies as an adjuvant treatment to improve this physiological immune deficiency, with different outcomes.

METHODS

Very low birth weight (VLBW) infants who developed sepsis in the neonatal ICU were studied. They were randomly divided in 2 groups: one group was treated with antibiotics (Group I), and the other received antibiotics plus a 500 mg/kg/day of IVIG during 7 days (Group II). Serum IgG concentration was determined at initiation, during and after treatment Group I, and daily during the 7 days of therapy in Group II.

RESULTS

The baseline IgG concentration in group II was 486 g/dL, and increased to 852 mg/dL after the first dose of IVIG (p < 0.01). After the seventh day of infusion a mean IgG level of 1898 mg/dL was achieved. A direct correlation (r = 0.94) between IgG concentration and days of treatment was observed. Blood cultures were positive in 70% of the infants in group I and 75.5% in group II. Staphylococcus epidermidis was the most frequent isolated bacteria in blood cultures. The lethality rate was 25.0% in group I and 5.0% in Group II (p < 0.03). We did not observe collateral effects with the administration of IVIG.

CONCLUSIONS

Prolonged therapy with IVIG seems to be safe and effective as an adjuvant treatment in VLBW infants with sepsis.

Profound Pathogen-Specific Alterations in Intestinal Microbiota Composition Precede Late-Onset Sepsis in Preterm Infants: A Longitudinal, Multicenter, Case-Control Study

BACKGROUND

The role of intestinal microbiota in the pathogenesis of late-onset sepsis (LOS) in preterm infants is largely unexplored but could provide opportunities for microbiota-targeted preventive and therapeutic strategies. We hypothesized that microbiota composition changes before the onset of sepsis, with causative bacteria that are isolated later in blood culture.

METHODS

This multicenter case-control study included preterm infants born under 30 weeks of gestation. Fecal samples collected from the 5 days preceding LOS diagnosis were analyzed using a molecular microbiota detection technique. LOS cases were subdivided into 3 groups: gram-negative, gram-positive, and coagulase-negative Staphylococci (CoNS).

RESULTS

Forty LOS cases and 40 matched controls were included. In gram-negative LOS, the causative pathogen could be identified in at least 1 of the fecal samples collected 3 days prior to LOS onset in all cases, whereas in all matched controls, this pathogen was absent (P = .015). The abundance of these pathogens increased from 3 days before clinical onset. In gram-negative and gram-positive LOS (except CoNS) combined, the causative pathogen could be identified in at least 1 fecal sample collected 3 days prior to LOS onset in 92% of the fecal samples, whereas these pathogens were present in 33% of the control samples (P = .004). Overall, LOS (expect CoNS) could be predicted 1 day prior to clinical onset with an area under the curve of 0.78.

CONCLUSIONS

Profound preclinical microbial alterations underline that gut microbiota is involved in the pathogenesis of LOS and has the potential as an early noninvasive biomarker.

Safety and Efficacy of Daptomycin in Neonates with Coagulase-Negative Staphylococci: Case Series Analysis

There has been an increase in the prevalence of gram-positive bacteremia in neonates in the last two decades. However, as a consequence of better care, there has been an increase in the survival of premature neonates. Coagulase-negative staphylococci (CoNS) is the most prevalent bacteria, responsible for up to 60% of late-onset sepsis (LOS). Daptomycin, a lipopeptide antimicrobial agent, is active against CoNS. This was an observational, retrospective case series study carried out in the Pediatric Hospital of King Saud Medical City, Riyadh, Saudi Arabia. The medical records of 21 neonates, aged 0-28 days, who were treated in Neonatal Intensive Care Unit (NICU) with intravenous daptomycin as monotherapy or combination therapy for at least 4 days for proven gram-positive infection between June 2019 to July 2020, were included. The median gestational and chronological age were 27 weeks and 5 days, respectively. The most frequent diagnosis in neonates was infective endocarditis (42.9%). Of the 21 patients who received daptomycin therapy, 13 (62%) recovered and 8 died. The clinical cure rate was higher in Staphylococcus hominis (100%) and in patients who received 6 mg/kg/dose twice daily (62.5%). The mean of aspartate aminotransferase significantly elevated after starting daptomycin (p = 0.048). However, no muscular or neurological toxicity of daptomycin was documented in any of the cases. Overall, daptomycin was well tolerated, even with long-term treatment.

Single-Cell Mapping of Progressive Fetal-to-Adult Transition in Human Naive T Cells

Whereas the human fetal immune system is poised to generate immune tolerance and suppress inflammation in utero, an adult-like immune system emerges to orchestrate anti-pathogen immune responses in post-natal life. It has been posited that cells of the adult immune system arise as a discrete ontological "layer" of hematopoietic stem-progenitor cells (HSPCs) and their progeny; evidence supporting this model in humans has, however, been inconclusive. Here, we combine bulk and single-cell transcriptional profiling of lymphoid cells, myeloid cells, and HSPCs from fetal, perinatal, and adult developmental stages to demonstrate that the fetal-to-adult transition occurs progressively along a continuum of maturity-with a substantial degree of inter-individual variation at the time of birth-rather than via a transition between discrete waves. These findings have important implications for the design of strategies for prophylaxis against infection in the newborn and for the use of umbilical cord blood (UCB) in the setting of transplantation.

Epidemiology and risk factors for recurrent Staphylococcus aureus colonization following active surveillance and decolonization in the NICU

OBJECTIVES

To examine neonatal risk factors associated with recurrent Staphylococcus aureus colonization and to determine the genetic relatedness of S. aureus strains cultured from neonates before and after decolonization.Study designSingle-center retrospective cohort study of neonates admitted to the neonatal intensive care unit (NICU) from April 2013 to December 2015, during which weekly nasal cultures from hospitalized NICU patients were routinely obtained for S. aureus surveillance.

SETTING

Johns Hopkins Hospital's 45-bed level IV NICU in Baltimore, Maryland.

METHODS

Demographics and clinical data were collected on all neonates admitted to the NICU with S. aureus nasal colonization who underwent mupirocin-based decolonization during the study period. A decolonized neonate was defined as a neonate with ≥1 negative culture after intranasal mupirocin treatment. Pulsed-field gel electrophoresis was used for strain typing.

RESULTS

Of 2,060 infants screened for S. aureus, 271 (13%) were colonized, and 203 of these 271 (75%) received intranasal mupirocin. Of those treated, 162 (80%) had follow-up surveillance cultures, and 63 of these 162 infants (39%) developed recurrent colonization after treatment. The S. aureus strains were often genetically similar before and after decolonization. The presence of an endotracheal tube or nasal cannula/mask was associated with an increased risk of recurrent S. aureus colonization (hazard ratio [HR], 2.65; 95% confidence interval [CI], 1.19-5.90; and HR, 2.21; 95% CI, 1.02-4.75, respectively).

CONCLUSION

Strains identified before and after decolonization were often genetically similar, and the presence of invasive respiratory devices increased the risk of recurrent S. aureus nasal colonization in neonates. To improve decolonization efficacy, alternative strategies may be needed.

Late onset sepsis: comparison between coagulase-negative staphylococci and other bacteria in the neonatal intensive care unit

OBJECTIVE

To compare demographic and clinical features of neonates with late-onset sepsis due to coagulase-negative-staphylococcus with those due to other bacterial pathogens.

STUDY DESIGN

Retrospective, population-based cohort study. Data on infants less than 90 days old diagnosed with late-onset bacterial sepsis in the neonatal intensive care unit were reviewed. Univariable and multivariable analysis were performed.

RESULTS

Two hundred and sixteen sepsis episodes were identified: coagulase-negative-staphylococcus caused 113 (52.3%) and other pathogen 103 (47.7%). Patients with coagulase-negative-staphylococcus sepsis had lower gestational age and younger age at onset, higher rates of parenteral nutrition exposure and normal temperature, lower rates of necrotizing enterocolitis, meningitis and neutropenia than patients with sepsis caused by other pathogens. In multivariable analysis, parenteral nutrition was the only independent risk factor for coagulase-negative-staphylococcus sepsis (odds ratio: 3.5, 95% confidence interval: 1.4-8.6).

CONCLUSIONS

Initial empiric treatment for suspected sepsis should be targeted for other pathogens than coagulase-negative-staphylococci and vancomycin treatment should be reserved for infants with specific risk factors and according to local antimicrobial susceptibility.

Clinical usefulness of catheter-drawn blood samples and catheter tip cultures for the diagnosis of catheter-related bloodstream infections in neonatology: A systematic review

OBJECTIVES

Neonatal sepsis is the most frequent health care-associated infection in neonatal units. This study aimed to analyze articles on the clinical usefulness of catheter-drawn blood samples and catheter tip cultures for the diagnosis of intravascular catheter-related bloodstream infection (CRBSI) in neonates.

METHODS

A systematic search was performed for studies published from 1987-2017, without language restriction. Observational studies carried out in neonates with CRBSI diagnosed using catheter-drawn blood samples or catheter tip cultures were included.

RESULTS

A total of 412 articles were identified in the databases and 10 articles were included. The 7 studies that evaluated central venous catheter tip cultures and cultures of catheter fragments presented sensitivities ranging from 58.5%-100% and specificities ranging from 60%-95.7%. Three studies that evaluated catheter-drawn blood cultures, paired with peripheral blood cultures, reported sensitivity and specificity of 94% and 71% when evaluated for the differential time to positivity. When quantitative evaluation was performed, the sensitivity and specificity were 80% and 99.4%.

CONCLUSIONS

Most of the studies analyzed cultures from the central venous catheter tip and catheter fragments for the diagnosis of CRBSI in neonatal populations. The results of this review suggest that the analysis of the catheter-drawn blood samples and catheter tip cultures, paired with peripheral blood cultures, are efficient methods for the diagnosis of CRBSI in neonates.

Characterization of hygiene habits and environments in children's care homes

OBJECTIVE

Identify the hygiene habits of children and caregivers in order to prevent and control infectious diseases in care environments in Bogotá, Colombia, as well as characterize the surface bacteria in these environments.

METHOD

Instruments were designed, validated and applied to evaluate healthy habits, with samples taken from surfaces in kitchens, bathrooms, halls, mats, and tools in 230 locations. Th e isolated bacteria were classifi ed using automated methodologies.

RESULTS

A total of 699 bacteria were isolated, with the largest growth percentage found in kitchens (36%). Th ese results are contrary to what was observed, where most of the kitchens appeared to be clean. In the survey, 93% of the caregivers reported washing their hands before handling food, and 23% said they used personal protection items when handling food.

CONCLUSION

There is a need for monitoring and interventions in hygiene and care habits in environments that care for children.

Multiresistant ST59-SCCmec IV-t437 clone with strong biofilm-forming capacity was identified predominantly in MRSA isolated from Chinese children

Background

This study aimed to investigate the clinical and molecular epidemiology and biofilm formation of Staphylococcus aureus (SA) isolated from pediatricians in China.

Methods

SA strains were isolated from Beijing Children’s hospital from February 2016 to January 2017. Isolates were typed by multilocus sequence typing (MLST), spa and SCCmec typing (for Methicillin-resistant SA [MRSA] only). Antimicrobial susceptibility testing was performed by agar dilution method except sulphamethoxazole/trimethoprim (E-test method). Biofilm formation and biofilm associated genes were detected.

Results

Totally 104 children (41 females and 63 males; median age, 5.2 months) were enrolled in this study, in which 60 patients suffered from MRSA infection. Among the 104 cases, 54.8% were categorized as community associated SA (CA-SA) infections. The children under 3 years were more likely to occur CA-SA infections compared with older ones (P = 0.0131). ST59-SCCmec IV-t437 (61.7%) was the most prevalent genotype of MRSA, and ST22-t309 (18.2%), ST5-t002 (9.1%), ST6-t701 (9.1%), ST188-t189 (9.1%) were the top four genotypes of methicillin-sensitive SA (MSSA). All the present isolates were susceptible to linezolid, vancomycin, trimethoprim-sulfamethoxazole, mupirocin, tigecyclin, fusidic acid. No erythromycin-susceptible isolate was determined, and only a few isolates (3.8%) were identified as susceptible to penicillin. Multi-drug resistant isolates were reponsible for 83.8% of the ST59-SCCmec IV-t437 isolates. The isolates with strong biofilm formation were found in 85% of MRSA and 53.2% of MSSA, and in 88.7% of ST59-SCCmec IV-t437 isolates. Biofilm formation ability varied not only between MRSA and MSSA (P = 0.0053), but also greatly among different genotypes (P < 0.0001). The prevalence of the biofilm associated genes among ST59-SCCmec IV-t437 clone was: icaA (100.0%), icaD (97.3%), fnbpA (100.0%), fnbpB (0), clfA (100%), clfB (100%), cna (2.7%), bbp (0), ebpS (88.5%), sdrC (78.4%), sdrD (5.4%), and sdrE (94.5%).

Conclusions

These results indicated strong homology of the MRSA stains isolated from Chinese children, which was caused by spread of multiresistant ST59-SCCmec IV-t437 clone with strong biofilm formation ability. The MSSA strains, in contrast, were very heterogeneity, half of which could produce biofilm strongly.

Electronic supplementary material

The online version of this article (10.1186/s12879-017-2833-7) contains supplementary material, which is available to authorized users.

Serum levels of vancomycin: is there a prediction using doses in mg/kg/day or m2/day for neonates?

Coagulase-negative Staphylococcus has been identified as the main nosocomial agent of neonatal late-onset sepsis. However, based on the pharmacokinetics and erratic distribution of vancomycin, recommended empirical dose is not ideal, due to the inappropriate serum levels that have been measured in neonates. The aim of this study was to evaluate serum levels of vancomycin used in newborns and compare the prediction of adequate serum levels based on doses calculated according to mg/kg/day and m²/day. This is an observational reprospective cohort at a referral neonatal unit, from 2011 to 2013. Newborns treated with vancomycin for the first episode of late-onset sepsis were included. Total dose in mg/kg/day, dose/m²/day, age, weight, body surface and gestational age were identified as independent variables. For predictive analysis of adequate serum levels, multiple linear regressions were performed. The Receiver Operating Characteristic curve for proper serum vancomycin levels was also obtained. A total of 98 patients received 169 serum dosages of the drug, 41 (24.3%) of the doses had serum levels that were defined as appropriate. Doses prescribed in mg/kg/day and dose/m²/day predicted serum levels in only 9% and 4% of cases, respectively. Statistical significance was observed with higher doses when the serum levels were considered as appropriate (p < 0.001). A dose of 27 mg/kg/day had a sensitivity of 82.9% to achieve correct serum levels of vancomycin. Although vancomycin has erratic serum levels and empirical doses cannot properly predict the target levels, highest doses in mg/kg/day were associated with adequate serum levels.

Empirical antimicrobial therapy for late-onset sepsis in a neonatal unit with high prevalence of coagulase-negative Staphylococcus

OBJECTIVE

The aim of this study was to compare two different empiric treatments for late-onset neonatal sepsis, vancomycin and oxacillin, in a neonatal intensive care unit with a high prevalence of coagulase-negative Staphylococcus.

METHODS

A cross-sectional study was conducted in an neonatal intensive care unit from 2011 to 2014. Data from the medical records of at-risk newborns were collected daily. Infections were defined according to the National Health Surveillance Agency criteria. Data analysis was performed using an internal program.

RESULTS

There was a significant reduction in the number of Staphylococcus aureus infections (p=0.008), without endocarditis, meningitis, or lower respiratory tract infection, as well as a reduction in the frequency of deaths related to S. aureus infection. There were no significant changes in the incidence of Gram-negative bacterial or fungal infections. An increase in coagulase-negative Staphylococcus infections was observed (p=0.022). However, there was no measured increase in related morbidity and mortality. There was a reduction in the median number of days of treatment with oxacillin from 11.5 to 6 days (p<0.001) and an increase of one day in the median number of days of treatment with vancomycin (p=0.046).

CONCLUSIONS

Modification of the empiric treatment regimen for neonatal late-onset sepsis with use of oxacillin showed a significant reduction in S. aureus infections, as well as a reduction in the frequency of infections with major organ system involvement and mortality due to infection with this microorganism. As a result, oxacillin can be considered as an effective treatment for late-onset sepsis, making it possible to avoid broad-spectrum antibiotics.