Gentamicin vs cefotaxime for therapy of neonatal sepsis. Relationship to drug resistance

An Overview of Antibiotic Therapy for Early- and Late-Onset Neonatal Sepsis: Current Strategies and Future Prospects

Neonatal sepsis is a clinical syndrome mainly associated with a bacterial infection leading to severe clinical manifestations that could be associated with fatal sequalae. According to the time of onset, neonatal sepsis is categorized as early- (EOS) or late-onset sepsis (LOS). Despite blood culture being the gold standard for diagnosis, it has several limitations, and early diagnosis is not immediate. Consequently, most infants who start empirical antimicrobial therapy do not have an underlying infection. Despite stewardship programs partially reduced this negative trend, in neonatology, antibiotic overuse still persists, and it is associated with several relevant problems, the first of which is the increase in antimicrobial resistance (AMR). Starting with these considerations, we performed a narrative review to summarize the main findings and the future prospects regarding antibiotics use to treat neonatal sepsis. Because of the impact on morbidity and mortality that EOS and LOS entail, it is essential to start an effective and prompt treatment as soon as possible. The use of targeted antibiotics is peremptory as soon as the pathogen in the culture is detected. Although prompt therapy is essential, it should be better assessed whether, when and how to treat neonates with antibiotics, even those at higher risk. Considering that we are certainly in the worrying era defined as the "post-antibiotic era", it is still essential and urgent to define novel strategies for the development of antibacterial compounds with new targets or mechanisms of action. A future strategy could also be to perform well-designed studies to develop innovative algorithms for improving the etiological diagnosis of infection, allowing for more personalized use of the antibiotics to treat EOS and LOS.

Optimal dose of cefotaxime in neonates with early-onset sepsis: A developmental pharmacokinetic model-based evaluation

Objective: The perspective of real-world study is especially relevant to newborns, enabling dosage regimen optimization and regulatory approval of medications for use in newborns. The aim of the present study was to conduct a pharmacokinetic analysis of cefotaxime and evaluate the dosage used in newborns with early-onset sepsis (EOS) using real-world data in order to support the rational use in the clinical practice.

Methods: This prospective, open-label study was performed in newborns with EOS. A developmental pharmacokinetic-pharmacodynamic model of cefotaxime in EOS patients was established based on an opportunistic sampling method. Then, clinical evaluation of cefotaxime was conducted in newborns with EOS using real-world data.

Results: A one-compartment model with first-order elimination was developed, using 101 cefotaxime concentrations derived from 51 neonates (30.1–41.3°C weeks postmenstrual age), combining current weight and postnatal age. The pharmacokinetic-pharmacodynamic target was defined as the free cefotaxime concentration above MIC during 70% of the dosing interval (70% fT > MIC), and 100% of neonates receiving the dose of 50 mg/kg, BID attained the target evaluated using the model. Additionally, only two newborns had adverse reactions possibly related to cefotaxime treatment, including diarrhea and feeding intolerance.

Conclusion: This prospective real-world study demonstrated that cefotaxime (50 mg/kg, BID) had a favorable efficacy and an accepted safety profile for neonates with EOS.

Practice Summary of Antimicrobial Therapy for Commonly Encountered Conditions in the Neonatal Intensive Care Unit: A Canadian Perspective

Neonates are highly susceptible to infections owing to their immature cellular and humoral immune functions, as well the need for invasive devices. There is a wide practice variation in the choice and duration of antimicrobial treatment, even for relatively common conditions in the NICU, attributed to the lack of evidence-based guidelines. Early decisive treatment with broad-spectrum antimicrobials is the preferred clinical choice for treating sick infants with possible bacterial infection. Prolonged antimicrobial exposure among infants without clear indications has been associated with adverse neonatal outcomes and increased drug resistance. Herein, we review and summarize the best practices from the existing literature regarding antimicrobial use in commonly encountered conditions in neonates.

Association of early life antibiotics and health outcomes: Evidence from clinical studies

Preterm infants are susceptible to infections that can rapidly progress to disastrous outcomes. Antibiotics are lifesaving, but their prolonged and inappropriate use are associated with adverse outcomes. In this review, we discuss the current status of antimicrobial use in the preterm neonatal population, and the challenges in determining the initiation, duration, and choice of antibiotics. Finally, we review the clinical studies on the potential consequences of prolonged antimicrobial exposure in prematurely born infants.

Comparison of Neonatal Outcomes With the Use Cefotaxime Versus Ceftazidime in a Neonatal Intensive Care Unit

OBJECTIVES

There is a national drug shortage of cefotaxime, and ceftazidime is recommended as an alternative to cefotaxime for neonates. This study evaluated culture-positive late-onset sepsis (LOS), multidrug resistant organisms (MDROs), and other neonatal outcomes with the use of ceftazidime compared with cefotaxime in neonates.

METHODS

This was a single-center, retrospective cohort study of neonatal subjects who received at least 24 hours of ceftazidime or cefotaxime between April 1, 2015, and August 1, 2017. Subjects were excluded if they received the alternate antibiotic for more than 24 hours.

RESULTS

A total of 101 subjects were included (ceftazidime, n = 58; cefotaxime, n = 43). Median gestational ages were significantly different between groups (28.1 [IQR, 25.0-36.6] weeks versus 32.3 [IQR, 26.9-37.4] in the ceftazidime and cefotaxime groups, respectively, p < 0.05). Results showed a non-statistically significant increased incidence of culture-positive LOS (17.2% versus 2.3%, respectively, adjusted OR 6.51 [95% CI, 0.78-55.23], p = 0.09) and MDRO infections (5.2% versus 0%, respectively, p = 0.26) with the use of ceftazidime compared with cefotaxime. There was a statistically significant increased risk of stage II to III necrotizing enterocolitis (NEC) with the use of ceftazidime (22.4% versus 2.3%, respectively, adjusted OR 9.68 [95% CI, 1.18-79.45], p = 0.04).

CONCLUSIONS

This study found a statistically significant increase in stage II to III NEC with the use of ceftazidime compared with cefotaxime. There was a higher rate of culture-positive LOS and MDRO infections with ceftazidime, but this was not significant. Further research is warranted to assess the implications ceftazidime use in neonates.

Pain Sensitization, Breastfeeding Effectiveness, and Parental Preferences by Antibiotic Route in Suspected Neonatal Sepsis

OBJECTIVES

Intravenous (IV) and intramuscular (IM) antibiotics have comparable efficacy in treating neonates undergoing sepsis evaluations. There are no clinical data favoring the use of either route regarding newborn pain and parental preferences. We hypothesized that pain associated with IM injections would worsen breastfeeding effectiveness and decrease parental satisfaction, making IV catheters the preferred route.

METHODS

This prospective cohort study took place in an academic institution with nurseries in 2 separate hospitals, 1 providing IV antibiotics, and the other, IM antibiotics. Newborns receiving 48 hours of antibiotics were compared by using objective pain and breastfeeding scores and parental surveys.

RESULTS

In 185 newborns studied, pain scores on a 7-point scale were up to 3.4 points higher in the IM compared with the IV group (P < .001). Slopes of repeated pain scores were 0.42 ± 0.08 and -0.01 ± 0.11 in the IM and IV groups, respectively (P = .002). Breastfeeding scores were similar between groups. Parents in the IV group were less likely to perceive discomfort with antibiotic administration (odds ratio [OR] 0.22; 95% confidence interval [CI] 0.06-0.74) but more likely to perceive interference with breastfeeding (OR 26; 95% CI 6.4-108) and bonding (OR 101; 95% CI 17-590) and more likely to prefer changing to the alternate route (OR 6.9; 95% CI 2.3-20).

CONCLUSIONS

IM antibiotics in newborns are associated with pain sensitization and greater pain than IV dosing. Despite accurately recognizing newborn pain with the IM route, parents preferred this to the IV route, which was perceived to interfere with breastfeeding and bonding.

Reduction of Inappropriate Antimicrobial Prescriptions in a Tertiary Neonatal Intensive Care Unit After Antimicrobial Stewardship Care Bundle Implementation

BACKGROUND

Our objective was to evaluate the appropriateness of antibiotic prescriptions in the neonatal intensive care unit using standardized criteria and determine the effects of an antimicrobial stewardship program (ASP) on patterns of antibiotic usage.

METHODS

A retrospective audit of antibiotic use from July 2010 to June 2013 was conducted, focusing on prescriptions of vancomycin, cefotaxime, meropenem and linezolid for >3 calendar-days. We evaluated the appropriateness of each course of antibiotic treatment based on the Centers for Disease Control and Prevention 12-Step Guidelines to Prevent Antimicrobial Resistance (steps 4, 6 and 9). An ASP was introduced in August 2014, and the same audit criteria were applied to review antimicrobial use in the subsequent 12 months.

RESULTS

In the pre-ASP era, 26.3%, 12.1%, 11.4% and 0% of meropenem, cefotaxime, vancomycin and linezolid courses, respectively, were inappropriate. The most common instance of inappropriate utilization included failure to use narrow-spectrum antimicrobials when appropriate. After the introduction of ASP program, 22.2%, 7.5%, 5.4% and 0% of meropenem, cefotaxime, vancomycin and linezolid courses, respectively, were inappropriate. The numbers of inappropriate antibiotic-days/1000 days of therapy with meropenem, cefotaxime and vancomycin changed from 1.89 to 1.96 [rate ratio (RR), 1.04 (0.70-1.52)], 3.56 to 1.73 [RR, 0.49 (0.33-0.71)] and 2.70 to 1.01 [RR, 0.37 (0.22-0.60)], respectively. In subgroup analysis, very low birth weight infants (birth weight, <1500 g) showed no improvement in the rates of inappropriate antibiotic prescriptions.

CONCLUSIONS

In this study, we found that ASP initiatives can be applied in neonatal populations to reduce inappropriate antimicrobial prescriptions, though a different approach may be needed among very low birth weight infants.

Inadequate use of antibiotics and increase in neonatal sepsis caused by resistant bacteria related to health care assistance: a systematic review

Background

Technologies and life support management have enhanced the survival of preterm infants. The immune system of newborns is immature, which contributes to the occurrence of healthcare-associated infections. The overlap of several conditions with neonatal sepsis and the difficulty of diagnosis and laboratory confirmation during this period result in a tendency to over-treat neonatal sepsis. The use of antimicrobial agents is a risk factor for multidrug-resistant bacterial infections. This work aimed to perform a systematic review of the relationship between inadequate use of antimicrobial agents and increase in neonatal sepsis related to healthcare assistance, due to bacterial resistance.

Methods

Our population, exposition, comparison, outcome and study type was as follows: P: hospitalized neonates with sepsis diagnosis, E: inappropriate use of antimicrobial agents, C: adequate use of antimicrobial agents or no indication of infection, O: resistant bacterial infection, and S: original studies. We performed searches in the PubMed, Scopus, Virtual Health Library (Scielo, LILACS, and MEDLINE), and Embase without limits on time, language, and the references of the articles found. Fourteen studies were included and assessed using the Grading of Recommendations, Assessment, Development, and Evaluation, Newcastle, and the Strengthening the Reporting of Observacional Studies in Epidemiology methodologies.

Results

All studies found were observational and started with a low-quality evidence level in the Grading of Recommendations, Assessment, Development, and Evaluation.

Conclusions

Despite their low-quality evidence, the studies demonstrated the association between inadequate use of antimicrobial agents and increase of neonatal resistant bacterial healthcare-associated infections in neonatal units. However, there is significant difficulty in conducting high-quality studies in this population due to ethical issues tied to randomized trials. Therefore, new studies should be encouraged to recommend adequate treatment of newborns without increasing the risk of healthcare-associated infections by multidrug-resistant bacteria.

Escherichia coli early-onset sepsis: trends over two decades

Escherichia coli early-onset sepsis (EOS) is an important cause of mortality and morbidity in neonates, especially in preterm and very low birth weight (VLBW) newborns. The aim of our study was to evaluate potential changes in the clinical and microbiological characteristics of E. coli EOS in our setting. Epidemiological, clinical, and microbiological data from all neonates with proven E. coli EOS from January 1994 to December 2014 were retrospectively collected in a single tertiary care hospital in Barcelona (Spain). Seventy-eight E. coli EOS cases were analyzed. A slight increase in the incidence of E. coli EOS was observed during the study period. VLBW newborns remained the group with higher incidence (10.4 cases per 1000 live births) and mortality (35.3%). Systematic use of PCR increased E. coli EOS diagnosis, mainly in the term newborn group. There was an increase in resistant E. coli strains causing EOS, with especially high resistance to ampicillin and gentamicin (92.8 and 28.6%, respectively). Nonetheless, resistant strains were not associated with poorer clinical outcomes.

CONCLUSIONS

There is an urgent need to reconsider the empirical therapy used in neonatal EOS, particularly in VLBW newborns. What is Known: • E. coli early-onset sepsis (EOS) and E. coli resistant strains have been described as overall stable but increasing in VLBW neonates (< 1.500 g) in previous studies. What is New: • Our study shows an increasing incidence of E. coli EOS in all age groups, overruling group B Streptoccocus for the last 10 years. E. coli resistant strains also increased equally in all age groups, with high resistance rates to our first line antibiotics (ampicillin and gentamicin). • Empiric antibiotic therapy of EOS, mainly in VLBW newborns, should be adapted to this new scenario.

A practical guide to the diagnosis, treatment, and prevention of neonatal infections

Neonatal infections continue to cause morbidity and mortality in infants. Among approximately 400,000 infants followed nationally, the incidence rates of early-onset sepsis infection within 3 days of life are 0.98 cases per 1000 live births. Newborn infants are at increased risk for infections because they have relative immunodeficiency. This article provides evidence-based practical approaches to the diagnosis, management, and prevention of neonatal infections.

Management of neonates with suspected or proven early-onset bacterial sepsis

With improved obstetrical management and evidence-based use of intrapartum antimicrobial therapy, early-onset neonatal sepsis is becoming less frequent. However, early-onset sepsis remains one of the most common causes of neonatal morbidity and mortality in the preterm population. The identification of neonates at risk for early-onset sepsis is frequently based on a constellation of perinatal risk factors that are neither sensitive nor specific. Furthermore, diagnostic tests for neonatal sepsis have a poor positive predictive accuracy. As a result, clinicians often treat well-appearing infants for extended periods of time, even when bacterial cultures are negative. The optimal treatment of infants with suspected early-onset sepsis is broad-spectrum antimicrobial agents (ampicillin and an aminoglycoside). Once a pathogen is identified, antimicrobial therapy should be narrowed (unless synergism is needed). Recent data suggest an association between prolonged empirical treatment of preterm infants (≥5 days) with broad-spectrum antibiotics and higher risks of late onset sepsis, necrotizing enterocolitis, and mortality. To reduce these risks, antimicrobial therapy should be discontinued at 48 hours in clinical situations in which the probability of sepsis is low. The purpose of this clinical report is to provide a practical and, when possible, evidence-based approach to the management of infants with suspected or proven early-onset sepsis.

Antibiotic therapy in neonatal and pediatric septic shock

Severe sepsis accounts for nearly 4,500 deaths (mortality rate 10%), and is responsible for nearly $2 billion annual healthcare expenditure in the United States. Early and speedy treatment of critically ill septic patients can halt or reduce the likelihood of physiologic progression to multi-system organ failure. A cornerstone of this therapeutic strategy is antibiotic administration. In this review, we discuss the empirical treatment strategies for the treatment of early and late neonatal sepsis, along with pediatric sepsis. Furthermore, we discuss the rationale that underlies the adoption of such treatment strategies. The present article also discusses the emergence of multi-drug organisms as the causative agents for sepsis, i.e. methicillin-resistant Staphylococcus aureus (MRSA), resistant enterococci and Klebsiella pneumoniae carbapenemases (KPC).

Choice of antibiotics in late neonatal sepsis in the extremely low birth weight infant

OBJECTIVE

To review the choice of antibiotics in treating suspected late neonatal sepsis in infants weighing 1000 g or less in a neonatal intensive care unit.

METHODS

Retrospective review of medical records.

RESULTS

Ninety-six infants weighing 1000 g or less were admitted to the neonatal intensive care unit during the study period. Sixty-two infants survived beyond four days of life and had at least one sepsis workup done to exclude late neonatal infection. Of the 62 study patients, 42 (68%) were started on ampicillin and netilmicin (A/N) and 20 (32%) were started on vancomycin and ceftizoxime (V/C) as the antibiotics of choice, pending culture results. Of the patients started on A/N, 17 of 42 had a positive blood culture compared with 11 of 20 on V/C (40% versus 55%, P=0.40). The mean (+/-SD) birth weight of infants started on A/N was 793+/-133 g compared with a mean of 728+/-153 g in the group that received V/C (P=0.09). Seven patients died in the A/N group compared with three in the V/C group (16.7% versus 15%, P=0.84). In addition to the sepsis episode studied, before they were discharged from hospital, 21 of 42 (50%) infants in the A/N group had further workups for suspected sepsis, compared with 16 of 20 (80%) (P=0.048) infants initially given V/C.

CONCLUSIONS

Ampicillin and netilmicin is a safe antibiotic combination for neonates suspected of late sepsis. This, in turn, may be important in reducing vancomycin overuse and the potential for bacterial resistance to this antimicrobial agent.

Antimicrobial use and bacterial resistance in neonatal patients

The neonatal population is at extremely high risk for developing infections. Because of the premature infant's prolonged length of stay, these patients may receive several courses of antibiotics while hospitalized. Although the number of antibiotics used in this population is limited, the dosing regimens must be carefully prescribed and adjusted to account for changing pharmacokinetic parameters. In addition, the development of antimicrobial resistance should always be a concern. The neonatal nurse can help ensure antimicrobial regimens are given appropriately and monitor these regimens for efficacy and toxicity.

Enteric gram-negative bacilli bloodstream infections: 17 years' experience in a neonatal intensive care unit

OBJECTIVE

To assess the occurrence of enteric gram-negative bacilli (EGNB) bloodstream infections (BSI) in a neonatal intensive care setting during a 17-year period in which a consistent antibiotic treatment program was in place. To document infections, outbreaks, or epidemics, emergence of antibiotic resistance, clinical correlates, and outcomes of the most prevalent EGNB (Escherichia coli, Klebsiella pneumoniae, and Enterobacter cloacae).

METHODS

This study analyzed demographic, clinical, and bacteriologic information from 360 infants born 1986-2002 who developed 633 blood culture-proven BSI. A total of 121 EGNB were isolated (E coli, K pneumoniae, and E cloacae). Early-onset BSI were discovered within 48 hours from birth, and late-onset BSI were those that occurred thereafter. Suspected early-onset BSI were treated with ampicillin and gentamicin, suspected late-onset BSI with vancomycin and gentamicin. Antibiotics were changed on the basis of organism antimicrobial susceptibility.

RESULTS

Early-onset BSI were noted in 52 of 21,336 (244/100,000) live births (1986-1991), 40 of 20,402 (196/100,000) live births (1992-1997), and 25 of 17,926 (139/100,000) live births (1998-2002). Of these cases, 39 were caused by E coli and 4 by K pneumoniae. Antibiograms for E coli isolated during the last 5 years of the study showed an increase in antibiotic resistance that coincided with obstetric group B streptococcus antepartum antibiotic prophylaxis. Group B streptococcus declined from 41 to 4 cases from the first to the last period. Late-onset BSI increased from 111 to 230 cases from the first to the second 6-year study period and declined modestly (171 cases) during the last. Fifteen percent (78 cases) of late-onset BSI were caused by EGNB, 5% by other gram-negative bacilli, 67% primarily by coagulase-negative staphylococcus, and 13% by fungus. Nonspecific clinical and hematologic signs of late-onset BSI were similar across EGNB species, but necrotizing enterocolitis was often associated with E coli, whereas pneumonia and prolonged thrombocytopenia characterized K pneumoniae infections. No outbreaks or epidemics were observed, and strains of EGNB with evidence of extended spectrum beta-lactamase production were never isolated.

CONCLUSION

Antepartum antibiotic prophylaxis may have increased antibiotic resistance in E coli isolates from early-onset BSI but has dramatically decreased group B streptococcus infections. Late-onset BSI caused by EGNB increased, but without changes in antibiotic susceptibility. In spite of medical advances, E coli, K pneumoniae, and E cloacae remain responsible for significant morbidity and mortality, especially in very low birth weight infants.

Neonatal sepsis: epidemiology and management

Neonatal sepsis is uncommon (2-4 per 1000 live births in developed countries), but the rate increases dramatically in premature newborns and those born to mothers with infections or prolonged rupture of the fetal membranes. While infections caused by organisms contracted from the mother at birth have decreased in the past two decades, there has been an increase in nosocomial infections. Today, most infants with sepsis have been hospitalized in neonatal intensive care units for weeks or months because of extreme prematurity, or because of a congenital malformation or surgical condition. Antimicrobial therapy is usually begun prior to the isolation of a pathogen and is based upon knowledge of the likely microbes in the particular clinical situation. The number of antimicrobial agents that can be safely used in neonates is relatively small, and dose administration usually needs to be adjusted based upon birthweight and post-gestational age. The decision whether to treat with antimicrobials should be made with consideration of the history, physical examination, and laboratory data. One should also consider the effects of the use of antimicrobials on the flora of the care unit. Bacterial resistance in the resident flora of the unit has become a major problem where there has been indiscriminate use of broad-spectrum agents.

Decreased antimicrobial resistance following changes in antibiotic use

The widespread use of perioperative antibiotic prophylaxis makes surgical procedures an important component of overall antibiotic use. Attempts to reduce costs and limit the emergence of resistance among pathogenic bacteria by altering antibiotic use must therefore encompass surgical prophylaxis. Several recent reports have linked the use of third-generation cephalosporins with beta-lactam resistance in gram-negative bacteria and with vancomycin resistance in Enterococcus. Fortunately, susceptibility can often be restored by replacing third-generation cephalosporins with drugs that are less likely to foster resistance; a penicillin/beta-lactamase inhibitor combination is often a suitable substitute. An antibiotic resistance management program can effect the type of changes in antimicrobial use necessary to forestall or reverse an outbreak of resistant pathogens. Such a plan was implemented at Methodist Hospital, Indianapolis, Indiana, in 1995. Piperacillin/tazobactam (in combination with an aminoglycoside) was added to the formulary, primarily as empiric therapy, replacing the use of third-generation cephalosporins such as ceftazidime. Following this change, the prevalences of vancomycin-resistant Enterococcus, methicillin-resistant Staphylococcus aureus, and other resistant gram-negative bacilli were all reduced. As this effective formulary change shows, appropriate changes in antibiotic drug, dosage, and administration route can limit the emergence of resistance and ultimately lower costs.

Evaluation and treatment of neonates with suspected late-onset sepsis: a survey of neonatologists' practices

OBJECTIVE

To ascertain current diagnostic and treatment practices for suspected late-onset sepsis in infants in neonatal intensive care units (NICUs) and identify areas that may benefit from clinical practice guidelines.

METHODS

During June 2000, we conducted a multicenter survey of neonatologists and infection control professionals regarding practices related to late-onset sepsis in NICUs at children's hospitals participating in the Pediatric Prevention Network.

RESULTS

Personnel at 35 hospitals with NICUs completed surveys; 34 were infection control professionals, and 278 were neonatology clinicians, primarily attending neonatologists or neonatology fellows. At these facilities, coagulase-negative staphylococci (CoNS) were the most frequent blood culture isolate from infants with late-onset sepsis accounting for 54% of bloodstream infections. When late-onset sepsis was suspected, 83% of clinicians drew only 1 blood culture when no central venous catheter was present or when a central vascular was present with no blood return. Thirty-two percent obtained 1 or more C-reactive protein concentration determinations. Sixty percent of clinicians prescribed a vancomycin-containing regimen for a 900 g, 3-week-old infant with suspected late-onset sepsis. The presence of a central venous catheter or shock increased empiric vancomycin use. The presence of methicillin-resistant Staphylococcus aureus in the NICU did not increase vancomycin use, but a vancomycin restriction policy decreased empiric vancomycin use. Clinicians at an individual NICU tended to have similar empiric antibiotic-prescribing practices: in 29 (83%) of 35 centers > or =75% of respondents had similar practice with regard to prescribing a vancomycin-containing regimen for empiric therapy. Forty-seven percent to 85% completed a full course of antimicrobials when a single blood culture was obtained and grew CoNS, but a significantly lower percentage of respondents (22%-47%) completed a full course when 1 of 2 blood cultures obtained grew CoNS. Eleven percent of respondents removed an umbilical catheter at the time of suspected sepsis, but fewer than 5% removed a nonumbilical central venous catheter for suspected sepsis. Most (> or =61%) retained a nonumbilical catheter despite documentation of CoNS bacteremia.

CONCLUSIONS

Neonatologists varied in management of suspected late-onset sepsis, particularly that caused by CoNS. Procedures to prevent CoNS-positive blood cultures and to differentiate CoNS contaminants from pathogens are needed. For safely decreasing vancomycin use in NICUs, clinical practice guidelines should be developed, implemented, and evaluated. The guidelines should include optimal skin antisepsis and catheter disinfection before obtaining blood for culture, obtaining 2 blood cultures and using adjunctive tests and information to help differentiate contaminants from pathogens, and restriction on empiric vancomycin use.

Antimicrobial control programs

The use of broad spectrum antimicrobials, the emergence of multiresistant organisms, and the hospital drug costs associated with antimicrobials have all driven the need for institutions to develop strategies to control the use of antimicrobials. Formulary restrictions, prior approval mechanisms, treatment guidelines, order forms, stop orders, antimicrobial management teams, computer-assisted decision support tools, antimicrobial rotation, and combinations of these practices have all been evaluated as methods to encourage the appropriate use of these agents. While many programs have been successful in reducing antimicrobial costs without compromising patient care, limited data are available on the impact of these programs on the development of multiresistant organisms, particularly in neonatal intensive care units. The optimal means for controlling the emergence of resistance have yet to be determined, but ongoing surveillance of antimicrobial utilization and susceptibility patterns are necessary to identify opportunities for interventions, maximize patient care, and potentially minimize the development of resistance.

Nosocomial pneumonia in pediatric patients: practical problems and rational solutions

Nosocomial pneumonia is a common hospital-acquired infection in children, and is often fatal. Risk factors for nosocomial pneumonia include admission to an intensive care unit, intubation, burns, surgery, and underlying chronic illness. Viruses, predominantly respiratory syncytial virus (RSV), are the most common cause of pediatric nosocomial respiratory tract infections. Gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa) are the predominant bacterial pathogens, and are associated with a high mortality rate. Staphylococcus aureus and Staphylococcus epidermidis are the most common Gram-positive bacteria causing nosocomial pneumonia; infections with these organisms have a better outcome than those with Gram-negative organisms. An increasing problem is the emergence of multiresistant Gram-positive and Gram-negative nosocomial pathogens. Distinguishing nosocomial pneumonia from other pulmonary processes may be difficult; diagnosis is based on clinical signs, radiological findings, and microbiological results. Recommended empiric therapy should consider factors such as the time of onset of illness, severity of disease, and specific risk factors for nosocomial pneumonia, including use of mechanical ventilation, underlying disease, or recent use of antibacterials. The resident local hospital flora should be considered when selecting therapy for nosocomial pneumonia. Early initiation of appropriate empiric therapy reduces morbidity and mortality. For empiric treatment of bacterial nosocomial pneumonia, an intravenous antibacterial regimen that includes coverage of Gram-negative bacilli and Gram-positive organisms should be used. A carbapenem or ureidopenicillin derivative (piperacillin) plus a beta-lactamase inhibitor should be used where extended spectrum beta-lactamase-producing Enterobacteriaceae are endemic. Therapy should be modified when a specific pathogen and its antimicrobial susceptibility are identified. Effective prevention of nosocomial pneumonia requires infection control measures that affect the environment, personnel, and patients. Of these, hand hygiene, appropriate infection control policies, and judicious use of antibacterials are essential.

Reduction in colonization and nosocomial infection by multiresistant bacteria in a neonatal unit after institution of educational measures and restriction in the use of cephalosporins

INTRODUCTION

Previous administration of third-generation cephalosporins predisposes to colonization and infections by multiresistant Enterobacter sp. The emergence of multiresistant bacteria infections in a neonatal unit during 1995, especially Enterobacter cloacae, stimulated this study.

OBJECTIVE

To evaluate the efficacy of measures to control colonization and nosocomial infection by multiresistant bacteria in a neonatal unit.

SETTING

A tertiary care university hospital.

PATIENTS AND METHODS

This study was conducted from October 1995 through December 1999 in 4 phases: a cross-sectional study, a longitudinal study with intervention measures, monthly cross-sectional studies, and determination of nosocomial infections caused by multiresistant bacteria (oxacillin-resistant Staphylococcus aureus and gram-negative bacteria resistant to either aminoglycosides or third-generation cephalosporins). Specimens for surveillance culture were obtained through umbilical and rectal swabs, and tracheal aspirates from intubated babies. The intervention measures were as follows: (1) appropriated training of the whole health care team, emphasizing measures to reduce cross-colonization, and the importance of rational usage of antibiotics and (2) suppression of usage of third-generation cephalosporins. Risk factors were analyzed through univariate and multivariate logistic regression.

RESULTS

In the first phase, 32% (10/31) of the patients were colonized by multiresistant bacteria (29% by multiresistant E cloacae ). In the second phase, 342 patients were evaluated; 33% of them were colonized by E cloacae, and a multiresistant strain was isolated in 10.8% (37/342) of the babies. A logistic regression model indicated parenteral nutrition and antibiotic usage as risk factors for colonization by multiresistant E cloacae. In the third phase, for 6 months, only 2 patients were colonized by multiresistant E cloacae. In the fourth phase, the analysis of bacterial resistance profile indicated a reduction of nosocomial infections due to multiresistant bacteria from 18 cases in 1995 to 2 cases per year until 1999.

CONCLUSION

These results have shown that the measures adopted were effective.

[Risk factors associated with nosocomial bacteremia in low birth weight neonates. Grady Memorial Hospital, Atlanta]

BACKGROUND

Nosocomial bloodstream infections occur frequently in Neonatal Intensive Care Units and are associated with recognized and unrecognized risk factors. Little has been published regarding risk factors for bloodstream infections in low birth weight neonates.

OBJECTIVE

To investigate risk factors for bloodstream infection in neonates < 1,500 g admitted at a Neonatal Intensive Care Unit.

METHODS

A prospective study was undertaken in low birth weight neonates (< 1,500g) during a 22 months period. Bivariant, and logistic regresion (stepwise procedure) analysis was used to determine the significance association of bloodstream infection and perinatal and nosocomial risk factors.

RESULTS

A total of 72 patiens with nosocomial bacteriemia and 147 non bacteriemic patients were studied. Independent risk factors associated with bloodstream infection were birth weight, persistence of umbilical catheter > 7 days and persistence of peripheral arterial catheter > 1 day.

CONCLUSIONS

The uses of umbilical catheter > 7 days, peripheral arterial catheter > 1 day and birth weight < 1,500 g were significant determinants of nosocomial bloodstream infection risk. Because of the importance of invasive procedures as a source of nosocomial bloodstream infections, the lines duration needs to be reviewed with the aim of reducing the incidence of blood stream infection.

Molecular typing demonstrating transmission of gram-negative rods in a neonatal intensive care unit in the absence of a recognized epidemic

Molecular typing techniques have been used in outbreak investigations. In this study, molecular typing techniques were used to track the spread of gram-negative rods (GNRs) in a neonatal intensive care unit (NICU) in the absence of an outbreak. Stool or rectal swab cultures for GNRs were obtained from all infants on admission, weekly, and on discharge. GNRs were tested for gentamicin susceptibility and were typed by contour-clamped homogeneous electric field electrophoresis. Transmission of identical strains of GNRs among infants was noted. Shared strains were more gentamicin resistant compared with unique strains (53% vs. 10%; P=.0001). Infants first colonized when they were >1 week of age had more total days of antibiotic treatment and had a higher rate of acquiring a shared and gentamicin-resistant strain, compared with infants colonized earlier. Antibiotic use increases colonization of infants in the NICU with resistant and shared strains of GNRs.

Meropenem in neonatal severe infections due to multiresistant gram-negative bacteria

Recently, new broad spectrum carbapenem has been investigated on a world-wide scale for the treatment of moderate to severe infections. In the neonatal intensive care units the extensive use of third generation cephalosporins for therapy of neonatal sepsis may lead to rapid emergence of multiresistant gram-negative organisms. We report the use of meropenem in 35 infants with severe infections due to Acinetobacter baumanii and Klebsiella pneumoniae. All gram negative bacteria were resistant to ampicillin, amoxicillin, ticarcilin, cefazoline, cefotaxime, ceftazidime, ceftriaxone and aminoglycosides. Eighty two percent of the cases (29/35) were born prematurely. Assisted ventilation was needed in 85.7% (30/35). All infants deteriorated during their conventional treatment and were changed to meropenem monotherapy. Six percent (2/35) died. The incidence of drug-related adverse events (mostly a slight increase in liver enzymes) was 8.5%. No adverse effects such as diarrhea, vomiting, rash, glossitis, oral or diaper area moniliasis, thrombocytosis, thrombocytopenia, eosinophilia and seizures were observed. At the end of therapy, overall satisfactory clinical and bacterial response was obtained in 33/35 (94.3%) of the newborns treated with meropenem. Clinical and bacterial response rates for meropenem were 100% for sepsis and 87.5% for nosocomial pneumonia. This report suggests that meropenem may be a useful antimicrobial agent in neonatal infections caused by multiresistant gram negative bacilli. Further studies are needed to confirm these results: Meropenem, newborn, sepsis and nosocomial infection.

An antibiotic policy to prevent emergence of resistant bacilli

BACKGROUND

Fear of infection in neonatal intensive care units (NICUs) often leads to early use of empiric broad-spectrum antibiotics, a strategy that selects for resistant bacteria. We investigated whether the emergence of resistant strains could be halted by modifying the empiric antibiotic regimens to remove the selective pressure that favours resistant bacteria.

METHODS

Two identical NICUs were assigned to different empiric antibiotic regimens. On unit A, penicillin G and tobramycin were used for early-onset septicaemia, flucloxacillin and tobramycin were used for late-onset septicaemia, and no broad-spectrum beta-lactam antibiotics, such as amoxicillin and cefotaxime were used. In unit B, intravenous amoxicillin with cefotaxime was the empiric therapy. After 6 months of the study the units exchanged regimens. Rectal and respiratory cultures were taken on a weekly basis.

FINDINGS

There were 436 admissions, divided equally between the two regimens (218 in each). Three neonates treated with the penicillin-tobramycin regimen became colonised with bacilli resistant to the empirical therapy used versus 41 neonates on the amoxicillin-cefotaxime regimen (p<.0001). The relative risk for colonisation with strains resistant to the empirical therapy per 1000 patient days at risk was 18 times higher for the amoxicillin-cefotaxime regimen compared with the penicillin-tobramycin regimen (95% CI 5.6-58.0). Enterobacter cloacae was the predominant bacillus in neonates on the amoxicillin-cefotaxime regimen, whereas Escherichia coli predominated in neonates on the penicillin-tobramycin regimen. These colonisation patterns were also seen when the units exchanged regimens.

INTERPRETATION

Policies regarding the empiric use of antibiotics do matter in the control of antimicrobial resistance. A regimen avoiding amoxicillin and cefotaxime restricts the resistance problem.

Antibiotics in neonatal infections: a review

The bacteria most commonly responsible for early-onset (materno-fetal) infections in neonates are group B streptococci, enterococci, Enterobacteriaceae and Listeria monocytogenes. Coagulase-negative staphylococci, particularly Staphylococcus epidermidis, are the main pathogens in late-onset (nosocomial) infections, especially in high-risk patients such as those with very low birthweight, umbilical or central venous catheters or undergoing prolonged ventilation. The primary objective of the paediatrician is to identity all potential cases of bacterial disease quickly and begin antibacterial treatment immediately after the appropriate cultures have been obtained. Combination therapy is recommended for initial empirical treatment in the neonate. In early-onset infections, an effective first-line empirical therapy is ampicillin plus an aminoglycoside (duration of treatment 10 days). An alternative is ampicillin plus a third-generation cephalosporin such as cefotaxime, a combination particularly useful in neonatal meningitis (mean duration of treatment 14 to 21 days), in patients at risk of nephrotoxicity and/or when therapeutic monitoring of aminoglycosides is not possible. Another potential substitute for the aminoglycoside is aztreonam. Triple combination therapy (such as amoxicillin plus cefotaxime and an aminoglycoside) could also be used for the first 2 to 3 days of life, followed by dual therapy after the microbiological results. In late-onset infections the combination oxacillin plus an aminoglycoside is widely recommended. However, vancomycin plus ceftazidime (+/- an aminoglycoside for the first 2 to 3 days) may be a better choice. Teicoplanin may be a substitute for vancomycin. However, the initial approach should always be modified by knowledge of the local bacterial epidemiology. After the microbiological results, treatment should be switched to narrower spectrum agents if a specific organism has been identified, and should be discontinued if cultures are negative and the neonate is in good clinical condition. Penicillins and third-generation cephalosporins are generally well tolerated in neonates. There is controversy regarding whether therapeutic drug monitoring of aminoglycosides will decrease toxicity (particularly renal damage) in neonates, and on the efficacy and safety of a single daily dose versus multiple daily doses of these drugs. Toxic effects caused by vancomycin are uncommon, but debate still exists over the need for therapeutic drug monitoring of this agent. When antibacterials are used in neonates, accurate determination of dosage is required, particularly for compounds with a low therapeutic index and in patients with renal failure. Very low birthweight infants are also particularly prone to antibacterial-induced toxicity.

Bloodstream infections in a neonatal intensive-care unit: 12 years' experience with an antibiotic control program

OBJECTIVE

To assess the prevalence of gram-positive coccal (GPC), gram-negative bacillary (GNB), and fungal blood-stream infections (BSIs) during a 12-year period in which a consistent antibiotic treatment protocol was in place; to evaluate the efficacy of these antibiotic policies in relation to treatment, to the emergence of bacterial or fungal resistance, and to the occurrence of infection outbreaks or epidemics.

STUDY DESIGN

Case series.

METHODS

Demographic, clinical, and bacteriological information from 363 infants born during 1986 through 1991 and 1992 through 1997 who developed 433 blood-culture-proven BSIs was analyzed. Early-onset BSIs were defined as those infections discovered within 48 hours of birth, and late-onset BSIs as those that occurred thereafter. Suspected early-onset BSIs were treated with ampicillin and gentamicin, and suspected late-onset BSIs with vancomycin and gentamicin. Antibiotics were changed on the basis of organism antimicrobial susceptibility.

RESULTS

Early-onset BSIs were noted in 52 of 21,336 live births and 40 of 20,402 live births during 1986 through 1991 and 1992 through 1997, respectively. GPC (83% due to group B streptococcus [GBS]) accounted for approximately one half of early-onset BSI cases and GNB (68% Enterobacteriaceae) for the remainder. Early-onset GBS declined from 24 to 11 cases (P=.04) and late-onset BSI increased from 111 to 230 cases (P<.01) from the first to the last study period. Sixty-eight percent of late-onset BSIs were due to GPC (primarily coagulase-negative Staphylococcus), 18% to GNB, and 14% to fungus. Over the study period, Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, and Pseudomonas aeruginosa isolated from the newborn intensivecare unit (unlike those strains from other hospital units) remained fully susceptible to ceftazidime and gentamicin. Although the hospitalwide prevalence of methicillin-resistant Staphylococcus aureus increased, all 17 newborn BSI cases were due to methicillin-sensitive strains. Prevalence of methicillin-resistant coagulase-negative Staphylococcus increased, although all strains remained vancomycin-susceptible, as did the 16 Enterococcus faecalis isolates. All fungi recovered (from 48 patients) were susceptible to amphotericin.

CONCLUSION

We observed a decrease in the prevalence of early-onset BSIs due to GBS and an increase in late-onset BSIs due to GPC, GNB, and fungi. The combination of ampicillin and gentamicin for suspected early-onset BSIs and vancomycin and gentamicin for late-onset BSIs has been successful for treatment of individual patients without the occurrence of infection outbreaks or the emergence of resistance. Controlled antibiotic programs and periodic evaluations based on individual unit and not on hospitalwide antibiograms are advisable.

Neonatal nosocomial infections

Nosocomial acquisition of infection is now the most common mode of transmission of infection in neonatal intensive care units (NICUs). Surveillance studies have shown rates of infection in the NICU of 15% to 20%, which are as high as those in adult medical or surgical ICUs and higher than those in most pediatric ICUs. Studies of NICU nosocomial infections have pinpointed the use of indwelling vascular catheters, high-calorie hyperalimentation infusions, assisted ventilation, and prior use of antibiotics as significant risk factors for infection. Strategies to reduce nosocomial infections with the use of prophylactic antibiotics, immunoglobulins, and physical barriers have been unsuccessful. New methods of reducing risk factors and enhancing the neonate's resistance to infection are badly needed.

Enterobacter spp.: pathogens poised to flourish at the turn of the century

Knowledge of the genus Enterobacter and its role in human disease has expanded exponentially in recent years. The incidence of infection in the hospital and the community has increased. New clinical syndromes have been recognized. Enterobacter spp. have also been implicated as causes of other syndromes that traditionally have been associated almost exclusively with more easily treatable pathogens, such as group A streptococci and staphylococci. Rapid emergence of multiple-drug resistance has been documented in individual patients during therapy and in populations and environments with strong selective pressure from antimicrobial agents, especially the cephalosporins. Therapeutic options for patients infected with multiply resistant strains have become severely limited. Carbapenems or, alternatively, fluoroquinolones are the most predictively active options, although resistance to both classes has been observed on rare occasions. Enterobacter spp. appear well adapted for survival and even proliferation as the turn of the century approaches.

Cefotaxime. A reappraisal of its antibacterial activity and pharmacokinetic properties, and a review of its therapeutic efficacy when administered twice daily for the treatment of mild to moderate infections

Cefotaxime is well established as an effective and well tolerated antibacterial drug for 3 times daily parenteral treatment of a variety of moderate to severe infections in hospitalised patients. Its frequency of administration has recently been reassessed with a 12-hourly regimen. Comparative studies in hospitalised patients with nosocomial or community-acquired lower respiratory tract infections, demonstrate the similar clinical and bacteriological efficacy of twice daily cefotaxime 1 or 2 g and the same daily dose of ceftriaxone, usually administered once daily. Cefotaxime 2 g twice daily was also similar in efficacy to ceftriaxone 2 g once daily. Retrospective and post-marketing studies also reveal the similar efficacy of cefotaxime administered twice and 3 times daily, and pharmacoeconomic studies suggest that total direct costs of treatment with cefotaxime compared is similar to that with other third generation cephalosporins in currently used dosage regimens. When administered twice daily, cefotaxime is, thus, an effective antibacterial agent for the treatment of hospitalised patients outside the intensive care unit with a variety of mild to moderate non-CNS infections caused by susceptible organisms. When appropriately administered twice daily there is potential to lower the cost of antibacterial treatment without compromising efficacy.

Colonization with antibiotic-resistant gram-negative organisms in a pediatric intensive care unit

OBJECTIVE

To measure the prevalence of colonization with antibiotic-resistant Gram-negative organisms and its association with potential risk factors, including antibiotic exposure, in a pediatric intensive care unit (ICU).

DESIGN

Prospective, observational study.

SETTING

A 16-bed tertiary care pediatric ICU.

PATIENTS

All children admitted to the pediatric ICU for > 24 hrs over a 5-month period.

MEASUREMENTS AND MAIN RESULTS

Two hundred ninety-six patients, approximately half of all patients admitted to the ICU, were enrolled in the study; 236 patients had sufficient data collected for analysis and were prospectively examined for nasopharyngeal and gastrointestinal colonization by antibiotic-resistant Gram-negative organisms (ceftazidime minimal inhibitory concentration of > 16 micrograms/mL, or tobramycin minimal inhibitory concentration > 8 micrograms/mL). Association between colonization and potential predisposing factors including demographics, diagnosis, Pediatric Risk of Mortality (PRISM) score, invasive instrumentation, and prior ICU antibiotic exposure was assessed. More than 20% of patients were found to be colonized with an antibiotic-resistant Gram-negative organism. Examination of the timing of colonization indicated that more than half were identified within 72 hrs of admision. Colonization was associated by unadjusted analysis to prior ICU antibiotic exposure, as well as by factors associated with the severity of illness (PRISM score and invasive instrumentation) and young age. However, when the independence of these factors was tested by logistic regression, prior antibiotic exposure was no longer associated with resistant organism colonization.

CONCLUSIONS

These data suggest that antibiotic-resistant Gram-negative organisms are a significant risk to intensively III children and that in many instances, they are imported into the unit or rapidly acquired from environmental reservoirs. Since risk factors for colonization are multiple, policies confined to antibiotic utilization within the ICU may have fixed, and possibly limited, benefit in their control.

Antibiotic-resistant gram-negative bacteria in the critical care setting

Gram-negative bacilli that are resistant to commonly used antibiotics are a growing problem in seriously ill, hospitalized patients. Numerous outbreaks involving these organisms have been reported in intensive care nurseries and among critically ill adults. In endemic situations, the major reservoir for these pathogens is the patient; occasionally, transmission from patient to patient occurs through the hands of caregivers. Although the degree of antibiotic use probably plays some role in the emergence of antibiotic-resistant gram-negative bacilli, this relationship has not been uniformly demonstrated, and other factors intrinsic to the organisms themselves and to the critically ill patient may play an important role.

Transient in vivo selection of a constitutively cephalosporin resistant Enterobacter cloacae causing ventriculitis

A case of neonatal ventriculitis complicating a ventriculoperitoneal shunt and caused by one strain of Enterobacter cloacae (as shown on pulsed field gel electrophoresis) is presented. Daily ventricular fluid cultures from day 1 to 9 revealed inducible cephalosporin resistance in all isolates except on days 3, 4 and 5 of therapy when isolates were constitutively resistant. This emergence of resistance due to constitutive Bush class 1 beta-lactamase production is an excellent example of the rapid emergence of a predominant strain of bacteria depending on antibiotic selection pressures in vivo. The transient nature of the predominant resistant phenotype may have been due to missing a dose of cefotaxime on day 5 or in vivo factors allowing persistence of sensitive organisms in antibiotic protected sites. Caution is advised in the use of cephalosporins alone for serious Enterobacter species infections. Repeat culture and sensitivity should be done in severe infections that are slow to respond to cephalosporin therapy.

Enterobacter cloacae in a neonatal intensive care unit: account of an outbreak and its relationship to use of third generation cephalosporins

After uneventful use of cefotaxime and ceftazidime as first line therapy for three years in our neonatal intensive care unit we isolated cephalosporin-resistant Enterobacter cloacae (CREC) strains which caused clusters of cases or colonization and/or serious neonatal infection. By using two or more typing methods, at least five different strains with similar patterns of antimicrobial sensitivities were identified. The results of a case-control study did not support the notion that the use of third generation cephalosporins was associated with colonization and infection by CREC. The outbreak was brought under control by interrupting the transmission of the epidemic strain D, by measures such as cohort nursing, diligent handwashing before and after procedures, and thorough environmental cleaning as well as by decontamination with glutaraldehyde after dismantling of the blood gas analyser believed to have acted as a persistent reservoir. Our experience highlights the danger of inadequate supervision and maintenance of equipment used for near-patient testing and the need to monitor such equipment not only in terms of its calibration and analytical performance but also microbiologically.

Beta-lactamases: current situation and clinical importance

Production of beta-lactamases is the most important means of bacterial resistance to beta-lactam antibiotics. The traditional, plasmid-mediated beta-lactamases were initially confined to Enterobacteriaceae but have now spread to other genera and species including Pseudomonas aeruginosa, Haemophilus influenzae, and Neisseria gonorrhoeae. Extended-spectrum plasmid-mediated beta-lactamases have been identified in Enterobacteriaceae, particularly Klebsiella spp. and Escherichia coli. They are capable of hydrolyzing second- and third-generation cephalosporins and older beta-lactams. Chromosomally mediated beta-lactamases may be produced constitutively or induced by the presence of a beta-lactam. Mutation within the bacterial genome may lead to constitutive enzyme hyperproduction. Strains that produce these enzymes are resistant to practically all beta-lactams, with the exception of carbapenems. The wide-spread occurrence of antibiotic resistance dictates that therapies be judiciously chosen with attention to the resistance patterns of the causative organisms.