Enterococcal Infection in Children

Physiologically-based pharmacokinetic modeling to predict the exposure and to assess pharmacodynamics of daptomycin in infants within 1 year old

Daptomycin is widely used in pediatric patients for serious infections caused by Gram-positive bacteria, however, studies regarding its safety and efficacy in infants within 1 year old are very limited. A physiologically-based pharmacokinetic (PBPK) model of daptomycin was built for children aged 1-17 years old and extrapolated to infants within 1 year old to evaluate pharmacodynamics (PD) based on efficacy and safety considerations. Monte Carlo Simulations (MCSs) were conducted to determine the probabilities of target attainment (PTA) and cumulative fractions of response (CFR) of daptomycin. The pharmacokinetic (PK) of daptomycin did not differ much in the population of infants within 1 year of age, with peak plasma concentration (Cmax) and area under the curve (AUC) maintained at an approximate level at all months of age, while the average trough concentration of daptomycin was 3.49 μg/mL when 10 mg/kg daptomycin was given, and 4.98 ug /mL at 15 mg/kg. According to the results of the MCSs, 10mg/kg daptomycin provides good antimicrobial effect for S.pneumoniae and MSSA. With the increase of dosage, the CFR value of daptomycin against MRSA, E.faecalis and E.faecium also gradually reached >90 %, except for E.faecalis with an average CFR of only 82.94 % at 12mg/kg. This is a daptomycin PBPK model in infants within 1 year of age, dose regimen higher than 10 mg/kg should be recommended for this population in the treatment of MRSA, E. faecalis, and E. faecalis.

Metagenomic-based pathogen surveillance for children with severe pneumonia in pediatric intensive care unit

Background

Pneumonia is a significant cause of morbidity and mortality in children. Metagenomic next-generation sequencing (mNGS) has the potential to assess the landscape of pathogens responsible for severe pulmonary infection.

Methods

Bronchoalveolar lavage fluid (BALF) samples of 262 children with suspected pulmonary infections were collected from April 2019 to October 2021 in the Pediatric Intensive Care Unit (PICU) of Guangdong Women and Children Hospital. Both mNGS and conventional tests were utilized for pathogen detection.

Results

A total of 80 underlying pathogens were identified using both mNGS and conventional tests. Respiratory syncytial virus (RSV), Staphylococcus aureus and rhinovirus were the most frequently detected pathogens in this cohort. The incidence rate of co-infection was high (58.96%, 148/251), with bacterial-viral agents most co-detected. RSV was the main pathogen in children younger than 6 months of age, and was also commonly found in older pediatric patients. Rhinovirus was prevalent in children older than 6 months. Adenovirus and Mycoplasma pneumoniae were more prevalent in children older than 3 years than in other age groups. Pneumocystis jirovecii was detected in nearly 15% of children younger than 6 months. Besides, influenza virus and adenovirus were rarely found in 2020 and 2021.

Conclusions

Our study highlights the importance of using advanced diagnostic techniques like mNGS to improve our understanding of the microbial epidemiology of severe pneumonia in pediatric patients.

Infant food production environments: A potential reservoir for vancomycin-resistant enterococci non-nosocomial infections

Enterococcus has been considered one of the most important nosocomial pathogens for human infections, and the hospital environment is an important reservoir for vancomycin-resistant enterococci (VRE) that leads to antimicrobial therapeutic failure. However, infant foods and their production environments could pose risks for the immature population, while this question remains unaddressed. This study conducted an extensive and thorough Enterococcus isolation, VRE risk assessment of the Chinese infant food production chains and additional online-marketing infant foods, including powdered infant formula (PIF) and infant complementary food (ICF). To investigate the prevalence of Enterococcus along infant food chains and commodities, a total of 482 strains of Enterococcus, including E. faecium (n = 363), E. faecalis (n = 84), E. casseliflavus (n = 13), E. mundtii (n = 12), E. gallinarum (n = 4), E. hirae (n = 4), and E. durans (n = 2) were recovered from 459 samples collected from infant food production chains (71/254) and food commodities (67/205). A decreasing trend for Enterococcus detection rate was found in the PIF production chain (PIF-PC), particularly during the preparation of the PIF base powder (From 100 % in raw milk to 8.70 % in end products), while an increasing trend was observed in the ICF production chain (ICF-PC) mainly during the initial processing of farm crops and the further processing of the product (20 % at farm crops increasing to 76.92 % at end products). The result indicated that the PIF-PC process effectively reduced Enterococcus contamination, while the ICF-PC showed the opposite trend. Importantly, eleven VRE isolates were recovered from the infant food production chain, including seven E. casseliflavus isolates carrying vanC2/C3 and four E. gallinarum isolates carrying vanC1. Ten VRE isolates were from food production environments. Collectively, our study demonstrated that infant food production environments represent potential reservoirs for VRE non-nosocomial infections in vulnerable populations.

Prevalence and Antibiotic Susceptibility Trends of Selected Enterobacteriaceae, Enterococci, and Candida albicans in the Subgingival Microbiota of German Periodontitis Patients: A Retrospective Surveillance Study

The periodontal microbiota is ecologically diverse and may facilitate colonization by bacteria of enteric origin (Enterobacteriaceae, Enterococci) and co-infections with Candida albicans, possibly producing subgingival biofilms with high antimicrobial tolerance. This retrospective surveillance study followed periodontitis-associated superinfection profiles in a large patient sample. From 2008 to 2015, biofilm samples from deep periodontal pockets were collected from a total of 16,612 German adults diagnosed with periodontitis. The presence of selected Enterobacteriaceae, Enterococci, and Candida albicans was confirmed in overnight cultures. Antimicrobial susceptibility of these clinical isolates was tested by disk diffusion with antibiotics routinely used for treatment of oral infections, e.g., amoxicillin (AML), amoxicillin/clavulanic acid (AMC), doxycycline (DO), and ciprofloxacin (CIP). The mean annual prevalence of patients harboring Enterobacteriaceae in periodontal plaques was 11.5% in total and ranged from 2.5% for Enterobacter cloacae to 3.6% for Klebsiella oxytoca, 1.1% for Klebsiella pneumoniae, 2.8% for Serratia marcescens, and 1.5% for Serratia liquefaciens. In comparison, the mean detection rates for microbiota typically found in the oral cavity were higher, e.g., 5.6% for Enterococcus spp. and 21.8% for Candida albicans. Among the Enterobacteriaceae, species harboring intrinsic resistance to AML (Enterobacter spp., Klebsiella spp., Serratia spp.) were predominant. Non-susceptibility to AMC was observed for Serratia spp. and Enterobacter cloacae. By contrast, Enterococcus spp. only showed non-susceptibility to DO and CIP. Trends for increasing resistance were found to AML in Serratia liquefaciens and to DO in Enterococcus spp. Trend analysis showed decreasing resistance to AMC in Serratia liquefaciens and Klebsiella oxytoca; and to DO in Serratia marcescens, liquefaciens, and Enterobacter cloacae. This study confirms the low but consistent presence of Enterobacteriaceae and Enterococci among the subgingival microbiota recovered from periodontitis specimen. Although their pathogenetic role in periodontal lesions remains unclear, their presence in the oral cavity should be recognized as a potential reservoir for development and spread of antibiotic resistance in light of antibiotic usage in oral infections.

An In vitro Study to determine the antibacterial activity of chlorhexidine and herbal mouthrinses against Enterococcus faecalis

Background:

Oral diseases have a strong history of treating by natural remedies. Chemical plaque reduction techniques, including dental mouthwashes, are intriguing because they can help patients who are unable to maintain appropriate mechanical plaque management. They are a less technically difficult alternative to mechanical control.

Aim:

This study aimed to compare the antibacterial efficacy of an herbal and 0.2% chlorhexidine gluconate mouthrinse against Enterococcus faecalis.

Methodology:

The antimicrobial effectiveness (zone of inhibition) of an herbal mouthrinse and chlorhexidine mouthrinse was determined by agar well diffusion method.

Results:

The zone of inhibition for control mouthrinse was 19 mm, and there was no zone of inhibition observed for the experimental mouthrinse.

Conclusion:

The result of this investigation suggests 0.2% chlorhexidine gluconate has a better antimicrobial activity than herbal mouthrinse.

Epidemiology and healthcare factors associated with neonatal enterococcal infections

OBJECTIVE

To investigate the epidemiology and healthcare factors associated with late-onset neonatal enterococcal infections.

DESIGN

Multicentre, multinational retrospective cohort study using prospectively collected infection data from a neonatal infection surveillance network between 2004 and 2016; this was supplemented with healthcare data from a questionnaire distributed to participating neonatal units.

SETTING

Sixty neonatal units across Europe (UK, Greece, Estonia) and Australia.

PATIENTS

Infants admitted to participating neonatal units who had a positive culture of blood, cerebrospinal fluid or urine after 48 hours of life.

RESULTS

In total, 414 episodes of invasive Enterococcus spp infection were reported in 388 infants (10.1% of a total 4083 episodes in 3602 infants). Enterococcus spp were the second most common cause of late-onset infection after coagulase-negative Staphylococcus spp and were strongly associated with necrotising enterocolitis (NEC) (adjusted OR 1.44, 95% CI 1.02 to 2.03, p=0.038), total parenteral nutrition (TPN) (adjusted OR 1.34, 95% CI 1.06 to 1.70, p=0.016), increasing postnatal age (per 1-week increase: adjusted OR 1.04, 95% CI 1.02 to 1.06, p<0.001) and decreasing birth weight (per 1 kg increase: adjusted OR 0.85, 95% CI 0.74 to 0.97, p=0.017). There was no evidence that inadequate nurse to patient staffing ratios in high-dependency units were associated with a higher risk of enterococcal infections.

CONCLUSIONS

Enterococcus spp were the second most frequent cause of late-onset infections. The association between enterococcal infections, NEC and TPN may inform empiric antimicrobial regimens in these contexts and provide insights into reducing these infections.

Fosfomycin in the pediatric setting: Evidence and potential indications

To date, there has been little experience in using fosfomycin in children. However, its broad spectrum of action and excellent safety profile have renewed interest in this antibiotic, especially for treating infections by multidrug-resistant bacteria. The main indication for fosfomycin in pediatrics is currently community-acquired lower urinary tract infection. Given its good activity against bacteria, fosfomycin can also be useful in urinary infections caused by extended-spectrum beta-lactamase-producing enterobacteria. Fosfomycin presents very good dissemination to tissues including bone and is therefore an option in the combined therapy of osteomyelitis, especially in cases produced by methicillin-resistant Staphylococcus aureus (MRSA) or in cases with beta-lactam allergies. Fosfomycin can also be employed in combination for multidrug-resistant Gram-negative bacteremia (especially carbapenemase-producing enterobacteria), S. aureus (if there is a high suspicion of MRSA or complicated infections) and vancomycin-resistant Enterococcus spp. Other infections in which fosfomycin could be part of a combined therapy include staphylococcal endocarditis (in case of beta-lactam allergy or MRSA), central nervous system infections (mainly by MRSA, S. epidermidis, Listeria and resistant pneumococcus), nosocomial pneumonia and infections associated with mechanical ventilation.

Impact on Public Health of the Spread of High-Level Resistance to Gentamicin and Vancomycin in Enterococci

Antibiotic resistance has turned into a global public health issue. Enterococci are intrinsically resistant to many antimicrobials groups. These bacteria colonize dairy and meat products and integrate the autochthonous microbiota of mammal's gastrointestinal tract. Over the last decades, detection of vanA genotype in Enterococcus faecium from animals and from food of animal origin has been reported. Vancomycin-resistant E. faecium has become a prevalent nosocomial pathogen. Hospitalized patients are frequently treated with broad-spectrum antimicrobials and this leads to an increase in the presence of VanA or VanB vancomycin-resistant enterococci in patients' gastrointestinal tract and the risk of invasive infections. In humans, E. faecium is the main reservoir of VanA and VanB phenotypes. Acquisition of high-level aminoglycoside resistance is a significant therapeutic problem for patients with severe infections because it negates the synergistic effect between aminoglycosides and a cell-wall-active agent. The aac(6')-Ie-aph (2″)-Ia gene is widely spread in E. faecalis and has been detected in strains of human origin and in the food of animal origin. Enzyme AAC(6')-Ie-APH(2″)-Ia confers resistance to available aminoglycosides, except to streptomycin. Due to the fast dissemination of this genetic determinant, the impact of its horizontal transferability among enterococcal species from different origin has been considered. The extensive use of antibiotics in food-producing animals contributes to an increase in drug-resistant animal bacteria that can be transmitted to humans. Innovation is needed for the development of new antibacterial drugs and for the design of combination therapies with conventional antibiotics. Nowadays, semi-purified bacteriocins and probiotics are becoming an attractive alternative to the antibiotic in animal production. Therefore, a better understanding of a complex and relevant issue for Public Health such as high-level vancomycin and gentamicin resistance in enterococci and their impact is needed. Hence, it is necessary to consider the spread of vanA E. faecium and high-level gentamicin resistant E. faecalis strains of different origin in the environment, and also highlight the potential horizontal transferability of these resistance determinants to other bacteria.

Enterococcus Species in the Oral Cavity: Prevalence, Virulence Factors and Antimicrobial Susceptibility

Enterococci are considered as transient constituent components of the oral microbiome that may cause a variety of oral and systemic infections. As there is sparse data on the oral enterococcal prevalence, we evaluated the Enterococcus spp. and their virulence attributes including antimicrobial resistance in a healthy Brazilian cohort. A total of 240 individuals in different age groups were studied (children 4–11 yrs, adolescents 12–17 yrs, young adults 18–29 yrs, adults 30–59 yrs, elderly over 60 yrs). Oral rinses were collected and isolates were identified by API 20 Strep and confirmed by 16S rDNA sequencing. E. faecalis isolates, in particular, were evaluated for virulence attributes such as their biofilm formation potential, and susceptibility to antimicrobials and an antiseptic, chlorhexidine gluconate. A total of 40 individuals (16.6%) and 10% children, 4% adolescents, 14% young adults, 30% adults, and 25% elderly carried oral enterococci. The oral enterococcal burden in adolescents was significantly lower than in the adults (p = 0.000) and elderly (p = 0.004). The proportion of carriers was higher among females (p = 0.001). E. faecalis was the most frequent isolate in all the age groups (p = 0.000), followed by E. durans and E. faecium. Whilst all the clinical isolates were able to form biofilms, only a proportion of them were able to produce lipase (92%), hemolysin (38%), and gelatinase (39%). Of all the isolates 53.8% were resistant to tetracycline, 12.3% to amoxicillin, 16.0% to ampicillin, 20.8% to chloramphenicol and 43.4% to erythromycin. None of the isolates were resistant to vancomycin. Our data suggest that in this Brazilian cohort the oral cavity may act as a significant reservoir of rather virulent and antibiotic resistant enterococci, with an increasing degree of carriage in the adults and elderly. Hence clinicians should be cognizant of this silent reservoir of virulent enterococci that may pose a particular threat of nosocomial infection.

A Meta-analysis of the Rates of Listeria monocytogenes and Enterococcus in Febrile Infants

CONTEXT

A change in the epidemiology of pathogens causing serious bacterial infection (SBI) has been noted since original recommendations were made for the empirical antibiotic choices for young infants with fever.

OBJECTIVE

To assess the prevalence of SBI caused by Listeria monocytogenes and Enterococcus species.

DATA SOURCES

A literature search was conducted on keywords related to SBI, L. monocytogenes, and Enterococcus spp. infections.

STUDY SELECTION

Eligible studies were those conducted in the United States and published between January 1998 and June 2014 focusing on SBI in infants≤90 days of age.

DATA EXTRACTION

The rates of urinary tract infection, bacteremia, and meningitis for each pathogen were recorded for each study. Meta-analysis was performed to calculate the prevalence for each pathogen in a random effects model with 0.5 continuity correction added to studies with zero events.

RESULTS

Sixteen studies were included. A total of 20,703 blood cultures were included, with weighted prevalences for L. monocytogenes and Enterococcus spp. bacteremia of 0.03% and 0.09%, respectively. A total of 13,775 cerebrospinal fluid cultures were included with event rates (unweighted prevalences) for L. monocytogenes and Enterococcus spp. meningitis of 0.02% and 0.03%, respectively. A total of 18,283 urine cultures were included, with no cases of L. monocytogenes and a weighted prevalence for Enterococcus spp. urinary tract infection of 0.28%.

LIMITATIONS

There may have been reporting bias or incomplete retrieval or inadvertent exclusion of relevant studies.

CONCLUSIONS

SBI caused by L. monocytogenes and Enterococcus spp. in febrile infants is rare, and therefore clinicians may consider a change in empirical antibiotic choices.

Population biology of intestinal enterococcus isolates from hospitalized and nonhospitalized individuals in different age groups

The diversity of enterococcal populations from fecal samples from hospitalized (n = 133) and nonhospitalized individuals (n = 173) of different age groups (group I, ages 0 to 19 years; group II, ages 20 to 59 years; group III, ages ≥60 years) was analyzed. Enterococci were recovered at similar rates from hospitalized and nonhospitalized persons (77.44% to 79.77%) of all age groups (75.0% to 82.61%). Enterococcus faecalis and Enterococcus faecium were predominant, although seven other Enterococcus species were identified. E. faecalis and E. faecium (including ampicillin-resistant E. faecium) colonization rates in nonhospitalized persons were age independent. For inpatients, E. faecalis colonization rates were age independent, but E. faecium colonization rates (particularly the rates of ampicillin-resistant E. faecium colonization) significantly increased with age. The population structure of E. faecium and E. faecalis was determined by superimposing goeBURST and Bayesian analysis of the population structure (BAPS). Most E. faecium sequence types (STs; 150 isolates belonging to 75 STs) were linked to BAPS groups 1 (22.0%), 2 (31.3%), and 3 (36.7%). A positive association between hospital isolates and BAPS subgroups 2.1a and 3.3a (which included major ampicillin-resistant E. faecium human lineages) and between community-based ampicillin-resistant E. faecium isolates and BAPS subgroups 1.2 and 3.3b was found. Most E. faecalis isolates (130 isolates belonging to 58 STs) were grouped into 3 BAPS groups, BAPS groups 1 (36.9%), 2 (40.0%), and 3 (23.1%), with each one comprising widespread lineages. No positive associations with age or hospitalization were established. The diversity and dynamics of enterococcal populations in the fecal microbiota of healthy humans are largely unexplored, with the available knowledge being fragmented and contradictory. The study offers a novel and comprehensive analysis of enterococcal population landscapes and suggests that E. faecium populations from hospitalized patients and from community-based individuals differ, with a predominance of certain clonal lineages, often in association with elderly individuals, occurring in the hospital setting.

Daptomycin in paediatrics: current knowledge and the need for future research

To overcome the problems stemming from antimicrobial resistance, there have been several attempts to develop new antimicrobials in recent years. Of the highly potent drugs targeting resistant Gram-positive bacteria, daptomycin has a number of attractive characteristics that suggest its possible use in the treatment of serious infections due to these organisms. Although several pharmacokinetic and clinical studies in adults have provided data to determine how this drug should be prescribed to obtain the maximal clinical efficacy without significant risks of severe adverse events, we have not yet solved all of the problems related to the use of this antibiotic in paediatric patients. In this paper, the resolved and lingering problems of daptomycin treatment in newborns and children are reviewed and discussed. Studies have indicated that daptomycin is a promising therapeutic option for the treatment of paediatric diseases caused by MDR Gram-positive bacilli. However, before daptomycin can be licensed for use in newborns and children, further studies are needed to establish the appropriate dosages for paediatric patients of different ages. The data collected in adults can only be transferred to children older than 12 years, and the information available is not sufficient to determine the dosage that will assure the highest antimicrobial efficacy with only marginal risks of adverse events in younger patients. Thus, studies in neonates and younger infants are urgently needed to permit the use of daptomycin in the first months of life, a period in which infections due to MDR Gram-positive pathogens are increasing.

Urinary tract infections in infants and children: Diagnosis and management

Recent studies have resulted in major changes in the management of urinary tract infections (UTIs) in children. The present statement focuses on the diagnosis and management of infants and children >2 months of age with an acute UTI and no known underlying urinary tract pathology or risk factors for a neurogenic bladder. UTI should be ruled out in preverbal children with unexplained fever and in older children with symptoms suggestive of UTI (dysuria, urinary frequency, hematuria, abdominal pain, back pain or new daytime incontinence). A midstream urine sample should be collected for urinalysis and culture in toilet-trained children; others should have urine collected by catheter or by suprapubic aspirate. UTI is unlikely if the urinalysis is completely normal. A bagged urine sample may be used for urinalysis but should not be used for urine culture. Antibiotic treatment for seven to 10 days is recommended for febrile UTI. Oral antibiotics may be offered as initial treatment when the child is not seriously ill and is likely to receive and tolerate every dose. Children <2 years of age should be investigated after their first febrile UTI with a renal/bladder ultrasound to identify any significant renal abnormalities. A voiding cystourethrogram is not required for children with a first UTI unless the renal/bladder ultrasound reveals findings suggestive of vesicoureteral reflux, selected renal anomalies or obstructive uropathy.

Treatment option for sepsis in children in the era of antibiotic resistance

Sepsis caused by multidrug-resistant microorganisms is one of the most serious infectious diseases of childhood and poses significant challenges for pediatricians involved in management of critically ill children. This review discusses the use of pharmacokinetic/dynamic principles (i.e., prolonged infusion of β-lactams and vancomycin, once-daily administration of aminoglycosides and rationale of therapeutic drug monitoring) when prescribing antibiotics to critically ill patients. The potential of 'old' agents (i.e., colistin, fosfomycin) and newly approved antibiotics is critically reviewed. The pros and cons of combination antibacterial therapy are discussed and finally suggestions for the treatment of sepsis caused by multidrug-resistant organisms are provided.

Polarity of extracts and fractions of four Combretum (Combretaceae) species used to treat infections and gastrointestinal disorders in southern African traditional medicine has a major effect on different relevant in vitro activities

ETHNOPHARMACOLOGICAL IMPORTANCE

Gastrointestinal disorders and infections are the major pathoaetiologies of diarrhoea causing many problems in human health and animal production. Many Combretum species are used in traditional medicine to treat infectious diseases including diarrhoea and many other ailments by rural people in Africa and Asia. Much of the work done to date on this genus was on the non-polar or intermediate polarity components. Some parameters that may cause diarrhoea and the evaluation of more polar extracts have apparently not been investigated.

AIMS

The polar components were extracted and fractionated by solvent-solvent fractionation to yield fractions with different polarities. The activity of these fractions on different parameters that could be involved in factors associated with diarrhoea was investigated. The cytotoxic activities of the extracts were also determined to evaluate the potential of these extracts to combat diarrhoea in production animals.

MATERIALS AND METHODS

Phenolic-enriched leaf extracts of Combretum bracteosum (COB), Combretum padoides (COP), Combretum vendae (COV) and Combretum woodii (COW) were obtained by extracting with a mixture of 70% acetone acidified with 1% HCl and n-hexane. Acetone was removed from a portion of the 70% acetone extract and it was sequentially treated by solvent-solvent fractionation with dichloromethane, ethyl acetate, and butanol to yield fractions with a large variation in polarity. The phenolic constituents of the extracts and fractions were determined using standard procedures The antioxidant activities were determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH); 2,2'-azino-bis (3-ethylbenzothiazoline)-6-sulphonic acid (ABTS(+)) radical scavenging, ferric reducing antioxidant power (FRAP) methods and lipid peroxidation inhibitory capacity standard methods. The ferric reducing antioxidant activities of the fractions were also determined. The minimum inhibitory concentrations (MICs) of the crude extracts and fractions against four bacterial and three fungal strains were assessed with a microplate serial dilution method. Cyclooxygenase (COX) and lipoxygenase (LOX) enzyme inhibitory assays and cytotoxicity studies against Vero cells were also carried out.

RESULT

Some of the fractions had much higher antioxidant activity than the positive controls. The average EC50 values of the extracts for the DPPH and ABTS antioxidant assays were 0.21-12µg/ml (COP), 0.25-16µg/ml (COV), 0.33-9.41µg/ml (COW) and 4.97-85µg/ml (COB) respectively while the mean EC50 values for the positive controls ascorbic acid and trolox were 1.28-1.51 and 1.02-1.19µg/ml respectively. All the crude extracts inhibited lipid peroxidation of linoleic acid by more than 80% at a concentration of 64 µg/ml. COP had the highest antibacterial activity with MICs ranging between 19-2500µg/ml, followed by COV with MICs ranging between 39-625µg/ml; COW and COB had similar MICs ranging between 39-2500µg/ml. COP also had the highest antifungal activity with MICs between 19-625µg/ml. The MIC for COW and COV ranged from 19 to 1250 µg/ml. COB had the lowest antifungal activity (MIC values were between 39 and 625 µg/ml). In general non-polar fractions had a high antimicrobial activity and polar fractions had a high antioxidant activity. The extracts had no activity against COX 1 and 2 enzymes in the anti-inflammatory assay but had good lipoxygenase inhibition. The crude extracts had high concentration of hydrolysable tannin (gallotannin). A good correlation (R(2)= 0.99) was found between the antioxidant activity and total tannin content indicating that, gallotannins may be responsible for the antioxidant activity.

CONCLUSION

The results obtained in this study with more polar extracts indicate that the use of extracts of these plant species as antidiarrhoeal agents may have a scientific basis. The extractant used here extracted a much higher percentage of the phytochemicals than acetone. It was better for isolating antioxidant compounds (polar) but not good for isolating antimicrobial compounds (non-polar) from the same species compared to acetone, ethyl acetate, dichloromethane, and hexane.

Use of linezolid in children: an overview of recent advances

Linezolid is the first member of a new generation of antibiotics, the synthetic oxazolidinones, to become available, with a broad spectrum of in vitro activity against gram-positive organisms, including methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus faecalis and vancomycin-resistant E. faecium. Linezolid is showing great promise currently for the treatment of multiresistant gram-positive bacterial infections, especially complicated skin infections, catheter-induced bacteremia or nosocomial pneumonia both in the community and in a hospital setting, in children and in adults. Although most recent reports are favorable and anticipatory of a more extensive use of linezolid in appropriately selected pediatric population groups in the near future, following treatment failure of conventional antimicrobial agents, more clinical trials are, however, required to investigate the safety profile and tolerability of this new antibiotic in the pediatric population.

Vancomycin-resistant Enterococcus outbreak in a neonatal intensive care unit: epidemiology, molecular analysis and risk factors

BACKGROUND

Vancomycin-resistant Enterococcus faecium (VRE) may cause outbreaks in neonatal intensive care units (NICU). We describe a biphasic VRE outbreak and identify risk factors for VRE acquisition.

METHODS

After the occurrence of 2 cases of VRE infections in a 44-bed NICU, a bundle of interventions was implemented that included active surveillance cultures for VRE, enhanced infection control measures, and audits on antimicrobial use, from June to December 2008. Analysis was performed using polymerase chain reaction and pulse-field gel electrophoresis techniques. A case-control study was conducted to identify risk factors.

RESULTS

Among 253 neonates screened, 101 (39.9%) were found to be colonized with VRE. During the first 9 weeks of the study period, 59 new cases were detected. Molecular analysis showed 1 predominant clone. During weeks 10-12, no new cases of VRE colonization were detected; however, at week 13, just when the outbreak appeared to be over, a second wave occurred, with 42 new cases and multiple clones detected. Multivariate analysis identified administration of antimicrobial therapy for late-onset neonatal sepsis and hospitalization during the first month of this outbreak as significant risk factors for VRE colonization.

CONCLUSION

Both a high prevalence of VRE colonization and antimicrobial use promoted the transmission of VRE during this biphasic outbreak. Adherence to infection control measures and antimicrobial stewardship policies are of utmost importance.

Evaluation of pharmacological activities, cytotoxicity and phenolic composition of four Maytenus species used in southern African traditional medicine to treat intestinal infections and diarrhoeal diseases

BACKGROUND

Microbial infections and resulting inflammation and oxidative stress are common pathogenesis of gastrointestinal tract (GIT) disorders. In South Africa, several species of the genus Maytenus are used in traditional medicine to treat various infectious diseases. Most of the previous work on this genus was focused on nonpolar extracts from the root and bark. In this study, leaf extracts of polar extracts of Maytenus peduncularis, Maytenus procumbens, Maytenus senegalensis and Maytenus undata were evaluated for antimicrobial, anti-inflammatory and antioxidant activities to determine their efficacy as therapeutic agents in GIT disorders.

METHODS

Phenolic-enriched leaf extracts and fractions were prepared by extracting with acidified 70% methanol and solvent-solvent fractionation. The activities of the fractions against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Enterococcus faecalis as well as clinical isolates of Aspergillus fumigatus, Candida albicans and Cryptococcus neoformans were determined using a serial microplate dilution method. Antioxidant activities were determined using 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azinobis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS), hydroxyl (OH) radical scavenging and linoleic acid peroxidation inhibitory assays. The phenolic composition as well as the cytotoxicity against Vero cell lines of the crude extracts was evaluated using various standard protocols.

RESULTS

The antimicrobial activities were concentrated in the non-polar fractions of hexane, dichloromethane and ethyl acetate (MICs 19-312 μg/ml). The crude extracts and polar fractions (butanol and water) had moderate to poor antimicrobial activity (MICs 312 to above 2500 μg/ml). The crude extracts and polar fractions had good antioxidant activity (EC50 values varied from 1.22 to 607 μg/ml, 1.71 to 312 μg/ml and 23 to 284 μg/ml for DPPH, ABTS and OH respectively. Linoleic acid peroxidation inhibition EC50 values of the crude extracts ranged between 27 and 39 μg/ml with relatively low toxicity against Vero cell lines (IC50 values 87 to 187 μg/ml). Fractionation of a crude extract with low activity could lead to fractions with more potent activity.

CONCLUSION

This study justifies the traditional use of leaf crude extracts and fractions from these four plants to remedy gastrointestinal disorders resulting from infection, inflammation and oxidative stress complications. The study also provides rationale for the use of leaf extracts with same beneficial effects in place of unsustainable root and bark harvest.

Screening fecal enterococci from Greek healthy infants for susceptibility to antimicrobial agents

Enterococci are among the first lactic acid bacteria to colonize the neonatal gastrointestinal tract, but they are also characterized as significant nosocomial pathogens. The aim of this study was to investigate the incidence of antibiotic resistance in enterococci isolated from neonates' gut microbiota as well as the presence of genetic determinants encoding for certain antibiotic resistance traits. A total of 263 fecal samples derived from 97 infants were collected on day 4, 30, and 90 after delivery. Enterococcus faecalis was the most frequently identified species (54.6%) followed by E. faecium, while E. casseliflavus/E. flavescens and E. gallinarum were also traced. The isolates were examined for their resistance to 12 antibiotics. Rifampicin resistance was the highest observed (53.2%), followed by resistance to tetracycline (42.0%), erythromycin (35.7%), and vancomycin (11.2%). Multiresistant strains were highly prevalent. Only intrinsic vancomycin resistance (vanC1 and vanC2/C3) was traced. The ermB gene was detected in 49 out of 96 erythromycin-resistant isolates, while tet genes were detected in 51 out of 113 tetracycline-resistant strains, with tet(L) being the most frequently observed. In conclusion, antibiotic-resistant enterococci are already established in the fecal microbiota of healthy neonates, from the first days of an infant's life.

Influence of antibiotic exposure in the early postnatal period on the development of intestinal microbiota

The influence of antibiotic exposure in the early postnatal period on the development of intestinal microbiota was monitored in 26 infants including five antibiotic-treated (AT) subjects orally administered a broad-spectrum antibiotic for the first 4 days of life and three caesarean-delivered (CD) subjects whose mothers were intravenously injected by the similar type of antibiotics in the same period. The faecal bacterial composition was analysed daily for the first 5 days and monthly for the first 2 months. Terminal restriction fragment length polymorphisms in the AT subjects showed less diversity with the attenuation of the colonization of some bacterial groups, especially in Bifidobacterium and unusual colonization of Enterococcus in the first week than the control antibiotic-free infants (AF, n=18). Quantitative real-time PCR showed overgrowth of enterococci (day 3, P=0.01; day 5, P=0.003; month 1, P=0.01) and arrested growth of Bifidobacterium (day 3, P=0.03) in the AT group. Furthermore, after 1 month, the Enterobacteriaceae population was markedly higher in the AT group than in the AF group (month 1, P=0.02; month 2, P=0.02). CD infants sustained similar, although relatively weaker, alteration in the developing microbiota. These results indicate that antibiotic exposure at the beginning of life greatly influences the development of neonatal intestinal microbiota.

Genetic analysis of faropenem-resistant Enterococcus faecalis in urinary isolates

We isolated faropenem-resistant Enterococcus faecalis in urine specimens and studied the mechanisms of resistance to faropenem in these isolates. Three mechanisms of penicillin resistance have been reported in E. faecalis; (1) beta-lactamase production, (2) overproduction of penicillin-binding protein (PBP) 4 or PBP5, and (3) decreasing affinities of penicillins for PBP4 by the occurrence of point mutations of the penicillin-binding domain. None of the E. faecalis isolates examined produced beta-lactamase or overproduced any PBPs, but the affinities of faropenem for PBP4 were decreased in faropenem-insensitive and -resistant strains. We found single amino acid substitutions at positions 475, 520 or 605 in PBP4 in the insensitive strains and two amino acid substitutions at positions 520 and 605 in PBP4 in the resistant strains by sequencing the entire pbp4 gene from each isolate. We conclude that development of resistance to faropenem in E. faecalis is due to decreasing affinities for PBP4 that are the result of the occurrence of one or two point mutations.