A pharmacologic evaluation of penicillin in children with purulent meningitis

Antibacterial mechanism of gold nanoparticles on Streptococcus pneumoniae

Streptococcus pneumoniae is a causal agent of otitis media, pneumonia, meningitis and severe cases of septicemia. This human pathogen infects elderly people and children with a high mortality rate of approximately one million deaths per year worldwide. Antibiotic-resistance of S. pneumoniae strains is an increasingly serious health problem; therefore, new therapies capable of combating pneumococcal infections are indispensable. The application of gold nanoparticles has emerged as an option in the control of bacterial infections; however, the mechanism responsible for bacterial cell lysis remains unclear. Specifically, it has been observed that gold nanoparticles are capable of crossing different structures of the S. pneumoniae cells, reaching the cytosol where inclusion bodies of gold nanoparticles are noticed. In this work, a novel process for the separation of such inclusion bodies that allowed the analysis of the biomolecules such as carbohydrates, lipids and proteins associated with the gold nanoparticles was developed. Then, it was possible to separate and identify proteins associated with the gold nanoparticles, which were suggested as possible candidates that facilitate the interaction and entry of gold nanoparticles into S. pneumoniae cells.

Serum bactericidal titres for monitoring antimicrobial therapy: current status and potential role in the management of multidrug-resistant Gram-negative infections

BACKGROUND

Serum bactericidal titres (SBTs) were widely used in the 1970s and 1980s to monitor antimicrobial therapy but are now seldom recommended. It is the only laboratory test that integrates drug pharmacodynamics, host pharmacokinetics and synergistic or antagonistic interactions of antimicrobial combinations into a single index of antimicrobial activity. We hypothesized that SBTs could play a renewed role in monitoring antibiotic treatment of multidrug-resistant Gram-negative infections. However, the last critical appraisal of the test was published over 30 years ago.

OBJECTIVES

This narrative review provides an updated assessment of the SBT test and its methodological limitations. We performed a diagnostic meta-analysis to estimate the value of SBTs for predicting clinical failure or death during antibiotic treatment.

SOURCES

A comprehensive literature search of PubMed including all English publications was performed in December 2019 using the Medical Subject Headings (MeSH search terms "serum", "bactericidal", "inhibitory", "titre", "monitoring", "anti-infective agents" "antimicrobial therapy" and "therapeutic drug monitoring").

CONTENT

Although standardized methods for performing SBTs were approved in 1999, the test remains labour intensive, and results may not be available until 72 hr. However, the use of non-culture-based endpoints (i.e. spectrophotometric or fluorescent) may shorten test time to 24 hr. Despite considerable heterogeneity in published studies, a meta-analysis of 11 evaluable studies published from 1974 to 2007 indicated a critical SBT result (peak SBT ≤1:8 or trough ≤1:2) is associated with a diagnostic odds ratio for clinical failure during antibiotic treatment of 12.27 (95% confidence interval 5.28-28.54) and a 5.32 (95% 1.32-21.42) odds of death.

IMPLICATIONS

SBTs have prognostic value for identifying patients at high risk for antibiotic treatment failure, but the slow turnaround time of the current test limits its clinical utility. Standardization of a more rapid SBT testing method is needed.

Use of Animal Models To Support Revising Meningococcal Breakpoints of β-Lactams

Antibiotic susceptibility testing (AST) in Neisseria meningitidis is an important part of the management of invasive meningococcal disease. It defines MICs of antibiotics that are used in treatment and/or prophylaxis and that mainly belong to the beta-lactams. The interpretation of the AST results requires breakpoints to classify the isolates into susceptible, intermediate, or resistant. The resistance to penicillin G is defined by a MIC of >0.25 mg/liter, and that of amoxicillin is defined by a MIC of >1 mg/liter. We provide data that may support revision of resistance breakpoints for beta-lactams in meningococci. We used experimental intraperitoneal infection in 8-week-old transgenic female mice expressing human transferrin and human factor H. Dynamic bioluminescence imaging was performed to follow the infection by bioluminescent meningococcus strains with different MICs. Three hours later, infected mice were treated intramuscularly using several doses of amoxicillin or penicillin G. Signal decreased during infection with a meningococcus strain showing a penicillin G MIC of 0.064 mg/liter at all doses. Signals decreased for the strain with a penicillin G MIC of 0.5 mg/liter only after treatment with the highest doses, corresponding to 250,000 units/kg of penicillin G or 200 mg/kg of amoxicillin, although this decrease was at a lower rate than that of the strain with a MIC of 0.064 mg/liter. The decrease in bioluminescent signals was associated with a decrease in the levels of the proinflammatory cytokine interleukin-6 (IL-6). Our data suggest that a high dose of amoxicillin or penicillin G can reduce growth during infection by isolates showing penicillin G MICs of >0.25 mg/liter and ≤1 mg/liter.

Vancomycin cerebrospinal fluid pharmacokinetics in children with cerebral ventricular shunt infections

This study described the cerebrospinal fluid (CSF) exposure of vancomycin in 8 children prescribed intravenous vancomycin therapy for cerebral ventricular shunt infection. Vancomycin CSF concentrations ranged from 0.06 to 9.13 mg/L and the CSF: plasma ratio ranged from 0 to 0.66. Two of 3 children with a staphylococcal CSF infection had CSF concentrations greater than minimal inhibitory concentration at the end of the dosing interval.

Bacterial meningitis post-PCV7: declining incidence and treatment

The epidemiology of bacterial meningitis in the United States has changed tremendously in the past 20 years. Since the introduction of the Haemophilus influenzae type b vaccine in 1988, the incidence of H. influenzae type b meningitis has declined by at least 97%, and Streptococcus pneumoniae has emerged as the most common etiologic agent. The PCV7 (7-valent pneumococcal conjugate vaccine [Prevnar]; Wyeth Pharmaceuticals) vaccine, which targets 7 pneumococcal serotypes, was introduced in 2000 and has had an enormous impact on both the incidence and epidemiology of bacterial meningitis. This article reviews the impact of the PCV7 vaccine and the most up-to-date evidence on diagnosis and empiric therapy of suspected bacterial meningitis in the current day.

Coadministration of the cyanobacterial lipopolysaccharide antagonist CyP with antibiotic inhibits cytokine production by an in vitro meningitis model infected with Neisseria meningitidis

OBJECTIVES

In this study, the objective was to determine the anti-inflammatory properties of CyP, a cyanobacterial lipopolysaccharide (LPS) antagonist, used in combination with antibiotic chemotherapy during infection of an in vitro meningitis model infected with Neisseria meningitidis (meningococcus).

METHODS

Monocultures of human meningioma cells and meningioma-primary human macrophage co-cultures were infected with meningococci (10(2)-10(8) cfu/monolayer) or treated with isolated outer membranes or purified LPS (0.1-100 ng/monolayer) from N. meningitidis. CyP (1-20 μg/monolayer) was added at intervals from t = 0 to 4 h, with and without benzylpenicillin (1-20 μg/monolayer). The antagonistic effect of CyP and its adjunctive properties to benzylpenicillin administration was determined by measuring cytokine levels in culture supernatants after 24 h.

RESULTS

CyP significantly inhibited (P < 0.05) the secretion of interleukin (IL)-6, IL-8, monocyte chemoattractant protein (MCP)-1 and RANTES ('regulated upon activation, normal T cell expressed and secreted') (overall reduction levels from 50% to >95%) by meningioma cell lines and meningioma-macrophage co-cultures challenged with either live meningococci or bacterial components. Inhibition was effective when CyP was added within 2 h of challenge (P < 0.05) and was still pronounced by 4 h. In the co-culture model, CyP alone partially inhibited IL-1β secretion, but did not prevent tumour necrosis factor (TNF)-α secretion, whereas penicillin alone inhibited IL-1β and TNF-α but conversely did not reduce MCP-1 and RANTES secretion. However, coadministration of CyP and penicillin in both models had an additive effect and restored the overall inhibitory profile.

CONCLUSIONS

CyP inhibits cytokine production in an in vitro meningitis model and augments the anti-inflammatory response when combined with benzylpenicillin. Administration of an LPS antagonist with antibiotic merits consideration in the emergency treatment of patients presenting with meningococcal infection.

Antibiotic resistance in invasive Streptococcus pneumoniae isolates identified in Scotland between 1999 and 2007

Data from 4727 invasive isolates of Streptococcus pneumoniae submitted to the Scottish Haemophilus, Legionella, Meningococcus and Pneumococcus Reference Laboratory between 1999 and 2007 were analysed to establish susceptibility profiles to penicillin, erythromycin and cefotaxime. Pneumococcal resistance to penicillin over the study period remained low, with only 0.2 % (n=7/4727) of isolates falling into this category (MIC ≥2 mg l(-1)). These isolates have been sporadic, and have mainly represented serogroup 14 (ST9) and 9 (ST156). In comparison, the 'intermediate sensitivity' group (MIC 0.12-1 mg l(-1)) ranged between 2 and 6 % per year, the majority from serogroup 9 (ST156). Over the study period, we found that 12 % (n=585/4727) of isolates were erythromycin-resistant (MIC >0.5 mg l(-1)), with the majority (n=467; 80 %) of these isolates identified as serogroup 14 (ST9). Cephalosporin resistance (cefotaxime MIC >1 mg l(-1)) was found in only 0.06 % (n=2/3135) of isolates. Internationally recognized clones (Pneumococcal Molecular Epidemiology Network) accounted for 35 % (n=28/81) of the penicillin non-susceptible isolates and 75 % (n=248/330) of the macrolide-resistant isolates, with ST9 and ST306 predominating. Between 1999 and 2007 we found that 11.6 % (n=18/155) of the penicillin non-susceptible isolates and 4.8 % (n=28/585) of the macrolide-resistant isolates were from serogroups not covered by the 7-valent conjugate pneumococcal vaccine in use in the UK since 2006. Susceptibility to first-line antimicrobial agents for invasive pneumococcal disease in Scotland remained high over the period 1999-2007.

Pharmacokinetics of penicillin g in very-low-birth-weight neonates

Data on the pharmacokinetics (PKs) of penicillin G (PEN) in neonates date back to the 1970s and do not include data for very-low-birth-weight (VLBW) neonates. The aim of this study was to describe the steady-state PKs and to establish an optimal regimen for the dosing of PEN in neonates with gestational ages of less than 28 weeks and birth weights of less than 1,200 g. Two PEN dosing regimens were studied: 50,000 IU (30 mg)/kg of body weight every 12 h (q12h) (group 1; n = 9) and 25,000 IU (15 mg)/kg q12h (group 2; n = 9). Samples for PK analysis were drawn before the injection of PEN and at 2 and 30 min and 1.5, 4, 8, and 12 h after intravenous injection of the third to eighth PEN doses. The PEN concentration was measured by a high-performance liquid chromatography with UV detection technique. The median peak and trough concentrations of PEN were 147 mug/ml (lower and upper quartiles, 109 and 157 mug/ml, respectively) and 7 mug/ml (lower and upper quartiles, 5 and 13 mug/ml, respectively) after administration of the dose of 50,000 IU and 59 mug/ml (lower and upper quartiles, 53 and 78 mug/ml, respectively) and 3 mug/ml (lower and upper quartiles, 3 and 4 mug/ml, respectively) after administration of the dose of 25,000 IU. The PEN half-life (median and lower and upper quartiles for group 1, 3.9 h and 3.3 and 7.0 h, respectively; median and lower and upper quartiles for group 2, 4.6 h and 3.8 and 5.6 h, respectively) was longer in VLBW neonates than in adults and term infants. PEN renal clearance correlated with creatinine clearance (R(2) = 0.309596; P = 0.038). Only a median of 34% (lower and upper quartiles, 28 and 37%, respectively) of the administered dose was excreted in urine within the following 12 h. We conclude that in VLBW infants a PEN dose of 25,000 IU (15 mg)/kg q12h is safe and sufficient to achieve serum concentrations above the MIC(90) for group B streptococci for the entire dosing interval.

Interlaboratory comparison of PCR-based methods for detection of penicillin G susceptibility in Neisseria meningitidis

We carried out a study for the nonculture detection of susceptibility of Neisseria meningitis to penicillin G in three laboratories of the European Monitoring Group on Meningococci (EMGM). Thirteen clinical samples (cerebrospinal fluids) and corresponding bacterial isolates from 13 cases of invasive meningococcal infection were distributed to the three laboratories. The MICs of penicillin G were determined for the isolates. Each laboratory used an "in-house" PCR-based method to determine alterations to the penA gene, which is associated with a reduced susceptibility to penicillin G. Nucleotide sequences from the 3' end of the penA gene were also determined. We observed a good correlation between genotyping of penA and the phenotypic determination (MIC) of susceptibility to penicillin G. The results obtained by the three methods for penA in the samples correlated very well with those obtained in bacterial isolates and with sequence data. The kappa coefficient that was used to estimate the level of agreement between genotypic results varied between 0.65 and 1, indicating a good agreement. This suggests that genotyping can predict susceptibility of N. meningitidis to penicillin G. These data strongly suggest that genotyping of penA should be used to determine meningococcal susceptibility to penicillin G in culture-negative cases. Although the nucleotide sequence of penA may be the gold standard in genotyping of penA, the less expensive PCR-based approach reported in this study may be quicker when a large number of isolates and clinical samples need to be tested.

Pharmacodynamic profiling of cefepime in plasma and cerebrospinal fluid of hospitalized patients with external ventriculostomies

Population pharmacokinetic (PK) modeling and Monte Carlo simulation (MCS) were used to describe the pharmacodynamic profile of cefepime in the both plasma and cerebrospinal fluid (CSF). Plasma and CSF cefepime data were obtained from a PK study of 7 hospitalized patients with external ventricular drains. Concentration-time profiles in plasma and CSF were modeled using a 3-compartment model with zero-order infusion and first-order elimination and transfer. Estimates of the PK parameters were identified in the Big Non Parametric Adaptive Grid with adaptive gamma (BigNPAG) program of Leary, Jelliffe, Schumitzky, and Van Guilder. MCS (10,000 subjects) was performed to estimate the probability of attaining the targets of free plasma concentration (20% protein binding) and total drug CSF concentration of 50-100% T>minimal inhibitory concentration (MIC) for MICs 0.06-8 mg/L for cefepime 2 g, iv, every 8 h (0.5-h infusion); cefepime 2 g, iv, every 12 h (0.5-h infusion); and cefepime 2 g (0.5-h infusion) once and 250 mg/h continuous infusion. After the Bayesian step, the observed-predicted regression and r(2) for plasma and CNS were as follows: plasma, observed=0.984 x predicted+2.570, r(2)=0.944; CSF, observed=0.785 x predicted+0.868, r(2)=0.821. The median penetration of cefepime as measured by AUC(CSF)/AUC(plasma) was 7.8%. In the MCS, the target attainment rates in plasma for 60-70% fT>MIC were high at each MIC value between 0.03 and 8 microg/mL for each regimen examined. In CSF, none of the regimens achieved 50-100% T>MIC for>80% of patients for MICs>0.5 mg/L.

Bacterial Meningitis in Children

Acute bacterial meningitis is still an important cause of morbidity and mortality in children worldwide. Recently, Haemophilus influenzae type b (Hib), once a common cause of meningitis, has virtually disappeared in developed nations, reflecting the overwhelming success of Hib vaccination. Unfortunately, Hib remains a significant pathogen in resource-poor countries. The introduction of the conjugated pneumococcal vaccine in 2000 may lead to similar future trends as witnessed with Hib. As the resistance of Streptococcus pneumoniae to penicillin and cephalosporins continues to evolve, vancomycin has become an important antibacterial in the treatment of bacterial meningitis. The unreliable penetration of this agent into cerebrospinal fluid is of concern, which is compounded by the controversial use of corticosteroids in paediatric meningitis. Some data suggest that in certain situations the addition of rifampicin (rifampin) to ceftriaxone may be a better choice. While dexamethasone is now considered the standard adjunctive therapy in the treatment of pneumococcal meningitis in adult patients, the benefit in children is not so clear and remains controversial; thus, there is no definitive paediatric recommendation. Several anti-inflammatory agents currently under investigation may be used in the future as adjunctive therapy for bacterial meningitis. It is clear that the current concepts in the treatment of childhood bacterial meningitis are evolving, and other antibacterial options and possible alternatives such as carbapenems and fluoroquinolones should be considered. Fluid restriction because of the Syndrome of Inappropriate Antidiuretic Hormone Secretion is widely advocated and used. Yet, this practice was recently challenged. It seems that most patients with meningitis do not need fluid restriction. The overwhelming success of the conjugated Hib vaccine and the encouraging results of the new conjugated pneumococcal and meningococcal vaccines suggest that the ideal management of bacterial meningitis is prevention and vaccines development against the most common bacterial agents are the best solution.

Rapid infectious killers

Central to the practice of emergency medicine is the ability to identify patients in whom immediate intervention is needed to prevent long-term morbidity and mortality. This article has highlighted some of the characteristics of several infectious diseases that may become fatal quickly if not treated quickly and appropriately by physicians. Bacterial meningitis,necrotizing soft tissue infections, invasive gram-negative disease, pneumo-coccal pneumonia, and West Nile encephalitis all require prompt recognition and treatment by emergency care providers.

Ampicillin and penicillin concentration in serum and pleural fluid of hospitalized children with community-acquired pneumonia

BACKGROUND

Optimal therapeutic efficacy of beta-lactam antibiotics for treatment of pneumococcal pneumonia is thought to be associated with the serum concentration greater than the minimum inhibitory concentration for 40-50% of the interdose interval at site of infection.

OBJECTIVE

Establish whether intravenous administration of ampicillin 400 mg/kg/day or penicillin 200,000 IU/kg/day in 6 divided doses reaches serum and or pleural concentrations above 4 microg/ml for at least 40% of the interdose interval.

MATERIALS AND METHODS

Hospitalized healthy children 1 month-14 years old with community-acquired bacterial pneumonia and empyema were eligible. Blood samples were obtained 30 min (C1) and 3 h (C2) after an antibiotic dose. Pleural fluid samples were obtained 1 and 4 h after the same dose in which blood samples were obtained. The concentrations were measured by high performance liquid chromatography.

RESULTS

The study included 17 patients treated with ampicillin and 13 treated with penicillin. For ampicillin, mean serum concentrations were C1 37.3 +/- 19 microg/ml and C2 11 +/- 10.2 microg/ml and mean pleural fluid concentrations were C1 25.8 +/- 9.9 microg/ml and C2 16.2 +/- 7.9 microg/ml. For penicillin, mean serum concentrations were C1 21.8 +/- 16.4 microg/ml and C2 23.9 +/- 3.4 microg/ml. Mean pleural fluid concentrations were C1 10.9 +/- 2.2 microg/ml and C2 7.7 +/- 3.4 microg/ml. In 8 of 30 patients, serum C2 was <4 microg/ml; in all of them serum concentrations were >4 microg/ml for >40% of the interdose interval.

CONCLUSIONS

This study of the pharmacokinetics of beta-lactam antibiotics in children with bacterial pneumonia may help in the development of therapeutic guidelines for the treatment of pneumococcal pneumonia.

Treatment of staphylococcal ventriculitis associated with external cerebrospinal fluid drains: a prospective randomized trial of intravenous compared with intraventricular vancomycin therapy

OBJECT

Staphylococcal ventriculitis may be a complication in temporary external ventricular drains (EVDs). The limited penetration of vancomycin into the cerebrospinal fluid (CSF) is well known; the pharmacodynamics and efficacy of systemically compared with intraventricularly administered vancomycin is examined in this prospective study.

METHODS

Ten patients in whom EVDs were implanted to treat intracranial hemorrhage and who were suffering from drain-associated ventriculitis were randomized into two treatment groups. Five of these patients (median age 47 years) were treated with 2 g/day vancomycin administered intravenously (four infusions/day, Group 1), and the other five(median age 49 years) received 10 mg vancomycin intraventricularly once daily (Group 2). Vancomycin levels were measured in serum and CSF six times a day. The maximum vancomycin level in CSF was 1.73 +/- 0.4 micro/ml in Group 1 and 565.58 +/- 168.71 microg/ml 1 hour after vancomycin application in Group 2 (mean +/- standard deviation). Vancomycin levels above the recommended trough level of 5 microg/ml in CSF were never reached in Group 1, whereas in Group 2 they below the trough level (3.74 +/- 0.66 microg/ml) only at 21 hours after intraventricular vancomycin application. The vancomycin level in the serum was constant within therapeutic levels in Group 1, whereas in Group 2 in most instances vancomycin was almost below a measurable concentration. In both groups bacteriologically and laboratory-confirmed CSF clearance could be obtained.

CONCLUSIONS

Intraventricular vancomycin application is a safe and efficacious treatment modality in drain-associated ventriculitis, with much higher vancomycin levels being achieved in the ventricular CSF than by intravenous administration.

Fatal outcome from meningococcal disease--an association with meningococcal phenotype but not with reduced susceptibility to benzylpenicillin

Penicillin has been the mainstay of treatment for meningococcal disease. Isolates of Neisseria meningitidis that are less susceptible to penicillin have been reported in several countries and in recent years have become more common. The clinical significance of this reduced susceptibility has not been investigated on a large scale. Hence, N. meningitidis isolates from culture-confirmed cases of meningococcal disease in England and Wales, between 1993 and 2000, were routinely serogrouped, serotyped and tested for susceptibility to penicillin. These data were linked to death registrations and analysed retrospectively. The changing trends in susceptibility were described and multivariate logistic regression was used to examine associations between strain characteristics and fatal outcome. The frequency of N. meningitidis isolates less susceptible to penicillin increased from < 6% in 1993 to > 18% in 2000. In particular, isolates expressing serogroup C with serotype 2b and serogroup W135 had a higher frequency of reduced penicillin susceptibility (49% and 55%, respectively). There was no evidence of an association between fatal outcome and infection with a less penicillin-susceptible isolate. Fatal outcome was associated with serogroup and serotype, with the odds of death for cases infected with C:2a and B:2a strains three-fold higher when compared with the baseline. For this large dataset the serogroup and serotype of the infecting strain influenced mortality from meningococcal disease and may be markers for hypervirulence. No association was found between reduced penicillin susceptibility and fatal outcome, but the increasing frequency of isolates less susceptible to penicillin highlights the need for continued surveillance.

Appropriate use of antimicrobials for drug-resistant pneumonia: focus on the significance of beta-lactam-resistant Streptococcus pneumoniae

The beta-lactam antibiotics (penicillins and cephalosporins) are commonly prescribed for the treatment of community-acquired pneumonia. However, Streptococcus pneumoniae, the most common etiologic agent of community-acquired pneumonia, has become increasingly resistant to beta-lactams over the past decade. The results of several studies suggest that penicillins remain effective for streptococcal pneumonia when the infecting pathogen has a minimal inhibitory concentration (MIC) </=2 microgram/mL, presumably because the pharmacokinetic and pharmacodynamic parameters associated with current dosing regimens are still sufficient. However, when the MIC >/=4 microgram/mL, increased rates of mortality (for patients who survive their first 4 days of hospitalization) may occur. Currently, 3.5%-7.8% of S. pneumoniae clinical isolates have MICs that fall in this latter class, but these rates may rise in the future. The clinical relevance of in vitro resistance may be related to at least 3 factors: concordance of antimicrobial therapy, severity of illness, and virulence.

Meningococcal disease: treatment and prevention

Many countries have been experiencing a significant increase in meningococcal disease. With the strains currently circulating, septicaemia is now a more frequent manifestation than meningitis and early recognition of disease manifestations by patient, parent or physician as well as early recognition of disease severity are the most important factors in attempting to reduce mortality and morbidity. Ceftriaxone is the treatment of choice but must be accompanied by aggressive supportive therapy in those with severe disease. The role of steroids is unknown. The evidence to support their use in both meningitis and severe systemic sepsis is discussed. The purified polysaccharide vaccines that have been available for some years may play a limited role in disease prevention. The recently introduced conjugate vaccine for preventing serogroup C disease represents a major advance but no vaccine is currently available to prevent serogroup B disease, cases of which will continue to challenge clinical practice.

Nonculture prediction of Neisseria meningitidis susceptibility to penicillin

We developed a nonculture method to predict the susceptibility of Neisseria meningitidis to penicillin G. The penA gene was amplified and submitted to restriction fragment length polymorphism analysis. This approach was first validated with a collection of 75 meningococcal strains of known phenotypes. It was next successfully applied to 29 clinical samples.

Neisseria meningitidis with decreased susceptibility to penicillin: report from the SENTRY antimicrobial surveillance program, North America, 1998-99

The purpose of this study was to estimate the prevalence of Neisseria meningitidis with decreased susceptibility to penicillin (MIC, >0.06 microg/mL) in North America (NA). Antimicrobial susceptibility testing by Etest (AB BIODISK, Solna, Sweden) was performed on 53 invasive clinical isolates obtained from 11 SENTRY Antimicrobial Surveillance Program participants in NA (9 states, 2 provinces) during 1998-99. All strains were markedly susceptible to ciprofloxacin (MIC(90), 0.008 microg/mL) and cefotaxime (MIC(90), < or = 0.002 microg/mL). Only 54.7% were susceptible to trimethoprim-sulfamethoxazole (TMP/SMX) at < or = 0.5/9.5 microg/mL. One strain was resistant to rifampin (MIC, > 32 microg/mL) and 16 isolates (30.2%) were relatively resistant to penicillin with MICs ranging from 0.094 to 0.25 microg/mL. No beta-lactamase production was detected. The serogroup distribution was 40% Y, 28% B, 24% C, 2% W-135, and 6% of strains were nongroupable. The prevalence of N. meningitidis with decreased susceptibility to penicillin in NA appears higher than previous reports.

Impact of antibiotic resistance on chemotherapy for pneumococcal infections

Over the past three decades, penicillin-resistant pneumococci have emerged worldwide. In addition, penicillin-resistant strains have also decreased susceptibility to other beta-lactams (including cephalosporins) and these strains are often resistant to other antibiotic groups, making the treatment options much more difficult. Nevertheless, the present in vitro definitions of resistance to penicillin and cephalosporins in pneumococci could not be appropriated for all types of pneumococcal infections. Thus, current levels of resistance to penicillin and cephalosporin seem to have little, if any, clinical relevance in nonmeningeal infections (e.g., pneumonia or bacteremia). On the contrary, numerous clinical failures have been reported in patients with pneumococcal meningitis caused by strains with MICs > or = 0.12 microg/ml, and penicillin should never be used in pneumococcal meningitis except when the strain is known to be fully susceptible to this drug. Today, therapy for pneumococcal meningitis should mainly be selected on the basis of susceptibility to cephalosporins, and most patients may currently be treated with high-dose cefotaxime (+/-) vancomycin, depending on the levels of resistance in the patient's geographic area. In this review, we present a practical approach, based on current levels of antibiotic resistance, for treating the most prevalent pneumococcal infections. However, it should be emphasized that the most appropriate antibiotic therapy for infections caused by resistant pneumococci remains controversial, and comparative, randomized studies are urgently needed to clarify the best antibiotic therapy for these infections.

Bacterial meningitis

In recent years, investigators have made significant advances in understanding the pathogenesis of bacterial meningitis, particularly with regard to understanding the cascade of biologic events that cause excessive inflammation within the central nervous system (CNS). Nevertheless, the most important event in the field of bacterial meningitis in the past decade is the dramatic decline in the incidence of Haemophilus influenzae meningitis in children as a result of the widespread use of the conjugated H. influenzae type b vaccine. Currently, the most important clinical challenge in this field is the emergence of the drug-resistant Streptococcus pneumoniae. This problem has significantly complicated initial management of patients with suspected bacterial meningitis. Preliminary data show promise with new conjugated S. pneumoniae vaccines.

Pharmacokinetics and pharmacodynamics of antibiotics in meningitis

The penetration of antimicrobials into the CSF is dependent on lipid solubility, molecular size, capillary and choroid plexus efflux pumps, protein binding, and the degree of inflammation. Penicillins, certain cephalosporins, carbapenems, fluoroquinolones, vancomycin, and rifampin provide the highest ratios of CSF levels to the MBC for common infecting organisms. For beta-lactam antibiotics, it is the duration of time that CSF concentrations exceed the MBC that determines the rate of bactericidal activity. It appears that levels should exceed the MBC for more than 50% of the dosing interval. The peak/MBC and AUC/MBC ratios are important determinants of efficacy for aminoglycosides and fluoroquinolones. Once-daily dosing of aminoglycosides is as effective as multiple-daily dosing regimens in experimental meningitis, probably because of drug-induced prolonged persistent effects. Fluoroquinolones do not produce as prolonged persistent effects and are slightly less effective when administered once daily. Although steroid use can reduce the penetration and decrease the bactericidal activity of some antimicrobials, such as vancomycin, in experimental meningitis, the clinical impact of steroid use in human meningitis is still unclear.

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.

Management of infections due to antibiotic-resistant Streptococcus pneumoniae

Antibiotic-resistant strains of Streptococcus pneumoniae are becoming more prevalent throughout the world; this has resulted in modifications of treatment approaches. Management of bacterial meningitis has the greatest consensus. Strategies for treating other systemic infections such as pneumonia, bacteremia, and musculoskeletal infections are evolving, in part related to the availability of new antibiotics which are active in vitro against isolates resistant to penicillin and the extended-spectrum cephalosporins. However, there are currently very limited data related to the clinical efficacy of these new agents. The studies upon which current recommendations are based are reviewed. Otitis media represents the single most common infection due to S. pneumoniae. Recommendations for treatment of acute otitis media due to drug-resistant strains and the rationale for these recommendations are discussed.

Carriage of penicillin-resistant pneumococci in Malawian children

In a prospective study of pneumococcal carriage in 200 Malawian children under 5 years of age, 47.5% were carriers. The carriage rate was highest in those aged 3-12 months and did not vary with family size, nor was it higher in those who had recently been admitted to hospital. Nasopharyngeal swabs were significantly more efficient than throat swabs in detecting carriers (p < 0.001) but nasopharyngeal swabs alone would have missed seven (8%) carriers. Pneumococcal isolates from 22% of carriers and from eight cases of meningitis and one of empyema showed intermediate resistance to penicillin (MIC 0.1-1.0 mg/l). All were sensitive to the 3rd-generation cephalosporin cefotaxime but one of the penicillin-resistant pneumococci and two of the clinical isolates had increased MICs of cefuroxime (0.5 mg/l).

Therapy for children with invasive pneumococcal infections. American Academy of Pediatrics Committee on Infectious Diseases

This statement provides guidelines for therapy of children with serious infections possibly caused by Streptococcus pneumoniae. Resistance of invasive pneumococcal strains to penicillin, cefotaxime, and ceftriaxone has increased over the past few years. Reports of failures of cefotaxime or ceftriaxone in the treatment of children with meningitis caused by resistant S pneumoniae necessitates a revision of Academy recommendations. For nonmeningeal infections, modifications of the initial therapy need to be considered only for patients who are critically ill and those who have a severe underlying or potentially immunocompromising condition or patients from whom a highly resistant strain is isolated. Because vancomycin is the only antibiotic to which all S pneumoniae strains are susceptible, its use should be restricted to minimize the emergence of vancomycin-resistant organisms. Patients with probable aseptic (viral) meningitis should not be treated with vancomycin. These recommendations are subject to change as new information becomes available.

Once-daily gentamicin therapy for experimental Escherichia coli meningitis

In vitro and in vivo studies have demonstrated that the bacteriologic efficacy of once-daily aminoglycoside therapy is equivalent to that achieved with conventional multiple daily dosing. The impact of once-daily dosing for meningitis has not been studied. Using the well-characterized rabbit meningitis model, we compared two regimens of the same daily dosage of gentamicin given either once or in three divided doses for 24 or 72 h. The initial 1 h mean cerebrospinal fluid (CSF) gentamicin concentration for animals receiving a single dose (2.9 +/- 1.7 micrograms/ml) was threefold higher than that for the animals receiving multiple doses. The rate of bacterial killing in the first 8 h of treatment was significantly greater for the animals with higher concentrations in their CSF (-0.21 +/- 0.19 versus -0.03 +/- 0.22 log10 CFU/ml/h), suggesting concentration-dependent killing. By 24h, the mean reduction in bacterial titers was similar for the two regimens. In animals treated for 72 h, no differences in bactericidal activity was noted for 24, 48, or 72 h. Gentamicin at two different dosages was administered intracisternally to a separate set of animals to achieve considerably higher CSF gentamicin concentrations. In these animals, the rate of bacterial clearance in the first 8 h (0.52 +/- 0.15 and 0.58 +/- 0.15 log10 CFU/ml/h for the lower and higher dosages, respectively) was significantly greater than that in animals treated intravenously. In conclusion, there is evidence of concentration-dependent killing with gentamicin early in treatment for experimental E. coli meningitis, and once-daily dosing therapy appears to be at least as effective as multiple-dose therapy in reducing bacterial counts in CSF.

Penicillin- and cephalosporin-resistant strains of Streptococcus pneumoniae causing sepsis and meningitis in children with sickle cell disease

OBJECTIVE

We investigated the possibility that antimicrobial-resistant pneumococci were causing invasive disease in children with sickle-cell disease (SCD).

STUDY DESIGN

Records of all children with SCD observed at the Mid-South Sickle Cell Center (MSSCC) at LeBonheur Children's Medical Center were reviewed from January 1990 to June 1994. Children with SCD and pneumococcal sepsis were identified. The Streptococcus pneumoniae isolates from these children were examined for serotype and antimicrobial susceptibilities. Two additional children not observed in the MSSCC had pneumococcal sepsis caused by penicillin-resistant isolates and were also included.

RESULTS

Antimicrobial susceptibility testing of the six penicillin-resistant isolates revealed that four were resistant to trimethoprim-sulfamethoxazole, two to erythromycin, and one to clindamycin. The two isolates that were resistant to ceftriaxone also were multiply resistant. From the MSSCC, 26 children had pneumococcal sepsis during the 4 1/2-year period studied. Five of these children (19%) died. Four (15%), including one who died, were infected with penicillin-resistant strains.

CONCLUSION

Pneumococcal sepsis, meningitis, and infections of other foci in children with SCD may be caused by S. pneumoniae that is resistant to one or more antimicrobial agents, including penicillin. The addition of vancomycin to the antibiotics currently used for initial management should be considered in areas where the antibiotic resistance of S. pneumoniae is prevalent.

Antimicrobial activities of beta-lactam antibiotics and gentamicin against penicillin-susceptible and penicillin-resistant pneumococci

The MICs of penicillin and cefotaxime for a range of penicillin-susceptible and penicillin-resistant isolates of Streptococcus pneumoniae were unchanged by the addition of gentamicin. In time-kill studies the rate of killing was greater for 18 of 20 isolates in the presence of gentamicin. However, mean differences in killing after 6 h of incubation were modest, not exceeding 1 log10 unit.

The growing threat of antibiotic-resistant Streptococcus pneumoniae

Resistance to penicillin has spread worldwide during the past 25 years. Strains resistant to alternative antibiotics have also emerged. Strains resistant to multiple antibiotics increasingly are isolated worldwide. Recently, isolates of penicillin-resistant S. pneumoniae resistant to cefotaxime and ceftriaxone have caused meningitis. As a result, recommendations for the empiric therapy of pneumococcal infections, especially meningitis, are changing.

E test as susceptibility test and epidemiologic tool for evaluation of Neisseria meningitidis isolates

The E test (AB Biodisk, Solna, Sweden), a new approach developed to test antimicrobial susceptibility, was compared with the agar dilution method for seven-drug antibiogram analysis of Neisseria meningitidis isolates. The overall E-test quantitative accuracy (+/- 1 log2 dilution) was 93% compared with that of agar dilution testing. The E test was then used to perform the susceptibility tests on a 10-year sample of 102 N. meningitidis isolates, including 5 from a recent epidemic outbreak in the University of Iowa (Iowa City) community. The E test proved to be an efficient methodology for identifying common source clusters of meningococcal disease having resistance to rifampin or sulfonamides. Moreover, the data demonstrated a recent increase in penicillin MICs (MIC for 90% of strains, 0.094 microgram/ml) and an escalation of high-level resistance to trimethoprimsulfamethoxazole (33%) and rifampin (14%). The E test should be considered a simple and accurate susceptibility method for the emerging need to test meningococci and other pathogenic neisserias. Chocolate Mueller-Hinton agar was observed to provide the best support of growth and E-test MIC results that correlated well with results of the reference agar dilution method previously used for neisserias.

Vancomycin administration into the cerebrospinal fluid: a review

OBJECTIVE

To discuss administering vancomycin directly into the cerebrospinal fluid (CSF) to treat serious central nervous system (CNS) infections.

DATA SOURCES

References were obtained through an online search of MEDLINE, limited to material published in English. In addition, information was extracted from clinical trials, review articles, abstracts, and textbooks.

STUDY SELECTION

Systematic evaluation of this topic in humans has not been done in a prospective manner. Related research articles describing the pathophysiology of CNS infections, intrathecal drug administration, and case reports of CSF vancomycin administration were reviewed.

DATA EXTRACTION

Case reports regarding CSF vancomycin dosing were evaluated and included: drug dosing, infecting organism, infectious disease state, infectious outcome, CSF dynamics/flow abnormalities, methods of drug administration, drug monitoring, and toxicities.

DATA SYNTHESIS

The results of this review are based on qualitative evaluations of anecdotal case reports and a basic understanding of intrathecal and intraventricular drug dosing principles. CSF administration of vancomycin is an effective means of bypassing the blood-brain barrier to achieve greater drug concentrations within the CSF. Current limitations to the CSF administration of vancomycin include a lack of data describing its safety, efficacy, and pharmacokinetics.

CONCLUSIONS

CNS infections may require the CSF administration of vancomycin for successful eradication. Recommendations for dosing in the literature vary. Because of the potential toxicities associated with elevated CSF concentrations of vancomycin, dosing should be conservative.

Detection of pneumococci with increased resistance to penicillin and their clinical significance

Streptococcus pneumoniae isolates from blood, CSF, respiratory tract and other clinical specimens from 626 patients were tested for sensitivity to penicillin. The bacteria were collected from patients in different hospitals in Riyadh, Saudi Arabia. Using 1 microg oxacillin disk, 147 (23.5%) of these isolates were found to be relatively resistant to penicillin (RPR). When 358 pneumococcal isolates were tested for RPR using 1 or 10 unit penicillin disks and compared with the MIC or oxacillin disk, as many as 18% were incorrectly designated as sensitive meningitis, septicemia and pneumonia, the significance of determining their correct susceptibility to penicillin cannot be over emphasized.

Pediatric bacterial meningitis: is prior antibiotic therapy associated with an altered clinical presentation?

STUDY HYPOTHESIS

The clinical features of children treated with oral antibiotics before the diagnosis of bacterial meningitis differ from those who receive no antibiotics.

DESIGN

Retrospective case series.

SETTING

University medical center.

PARTICIPANTS

Two hundred fifty-eight children 24 months old or younger with bacterial meningitis hospitalized during a 12-year period. Eighty-three children were treated with oral antibiotics before the diagnosis of meningitis, and 175 children were not.

INTERVENTIONS

None.

METHODS

The emergency department chart and hospital records were reviewed for presenting demographic, historical, physical examination, and laboratory features. Clinical features of pretreated and untreated patients were compared.

RESULTS

Pretreated children demonstrated less frequent temperature of 38.3 C or higher, altered mental status and a longer duration of symptoms before diagnosis, with more frequent vomiting; ear, nose, and throat infections; and physician visits in the week before detection of meningitis (P less than .05 for all comparisons). There was no difference in incidence of upper respiratory symptoms, seizures, nuchal rigidity, Kernig's and Brudzinski's signs, focal neurologic signs, mortality, and length of hospitalization between groups.

CONCLUSION

Clinical features of children who have taken antibiotics before the detection of meningitis differ significantly from those who have not undergone antibiotic therapy. Physicians should be aware of these differences when evaluating young children on antibiotics for the possibility of meningitis.

Pneumococcal meningitis in a child with a ventriculo-peritoneal shunt

A case of pneumococcal meningitis in an infant with a ventriculo-peritoneal shunt is reported. There was initial failure of treatment with penicillin and cefotaxime in full dosage. Eradication of infection without shunt removal was eventually achieved by adding rifampicin to the antibiotic regime.

Penicillin-resistant pneumococci

Penicillin-resistant pneumococci were first reported in Australia in 1967 and appeared in the UK in 1976. Their prevalence is increasing but varies greatly worldwide. The mechanism of resistance lies in the alteration of penicillin-binding proteins. Penicillin-resistant strains are often also resistant to a variety of non-beta-lactam antibiotics. Many different serotypes have been found to be penicillin resistant, type 23 being the most common resistant serotype in the UK. Use of oxacillin discs is recommended for penicillin sensitivity testing, otherwise resistant isolates may escape detection. Treatment of infected patients depends on several factors including the degree of resistance of the infecting strain, the sensitivity to alternative agents and the achievable concentration of antibiotic at the site of the infection. Carriage of penicillin-resistant pneumococci is more common in children, especially the recently hospitalized and those recently exposed to antibiotics. Outbreaks of infection have occurred and various control measures have been suggested in attempts to limit the spread of resistant strains.

Congenital syphilis presenting in infants after the newborn period

BACKGROUND AND METHODS

There has been a recent, dramatic increase in the incidence of congenital syphilis, particularly in urban areas. We describe seven infants seen during one year who were first given a diagnosis of congenital syphilis at 3 to 14 weeks of age, when symptoms developed. We reviewed these infants' charts in order to ascertain the reasons for the failure to diagnose syphilis at birth and to identify the signs and symptoms of congenital syphilis in this group of infants.

RESULTS

At delivery, four of the infants and their mothers had negative qualitative rapid-plasma-reagin tests for syphilis. The other three mothers had been seronegative during the pregnancy and were therefore not tested at delivery; two of their infants were seronegative at birth, and one was not tested. When the infants became symptomatic between 3 and 14 weeks of age and were admitted to the hospital, all seven infants and the five mothers available for testing were found to be seropositive for syphilis. Four infants presented with a characteristic diffuse rash; the other three presented with fever and were found on admission to have aseptic meningitis. All these infants had multisystem disease, as evidenced by hepatomegaly, increased aminotransferase and alkaline phosphatase levels, anemia, and monocytosis. In all the infants syphilis responded to parenteral penicillin.

CONCLUSIONS

Congenital syphilis may be missed if serologic tests are not performed for both the mother and her infant at the time of delivery. Even when these tests are performed, some infants are not identified as having syphilis, probably because the infection is very recent and there has been insufficient time for an antibody response to develop. Some infants with congenital syphilis of later onset do not present with a typical rash; therefore, at least in areas where the disease is prevalent, serologic tests for syphilis should be included in the evaluation of all febrile infants, even those with negative results on serologic testing at birth.

Relative penicillin G resistance in Neisseria meningitidis and reduced affinity of penicillin-binding protein 3

We examined clinical isolates of Neisseria meningitidis relatively resistant to penicillin G (mean MIC, 0.3 micrograms/ml; range, 0.1 to 0.7 micrograms/ml), which were isolated from blood and cerebrospinal fluid for resistance mechanisms, by using susceptible isolates (mean MIC, less than or equal to 0.06 micrograms/ml) for comparison. The resistant strains did not produce detectable beta-lactamase activity, otherwise modify penicillin G, or bind less total penicillin. Penicillin-binding protein (PBP) 3 of the six resistant isolates tested uniformly bound less penicillin G in comparison to the same PBP of four susceptible isolates. Reflecting the reduced binding affinity of PBP 3 of the two resistant strains tested, the amount of 3H-labeled penicillin G required for half-maximal binding was increased in comparison with that of PBP 3 of the two susceptible isolates. We conclude that the mechanism of resistance in these meningococci relatively resistant to penicillin G was decreased affinity of PBP 3.

Characteristics and antibiotic therapy of adult meningitis due to penicillin-resistant pneumococci

Of 66 episodes of pneumococcal meningitis seen in Bellvitge Hospital, Barcelona, Spain (January 1981 to June 1987), 15 (23 percent) were due to penicillin-resistant pneumococci [minimal inhibitory concentrations (MICs) of 0.1 to 4 micrograms/ml]. Fifty percent of these strains were also resistant to chloramphenicol. Most were sporadic community-acquired cases. Clinical characteristics were similar in both penicillin-resistant and penicillin-sensitive cases. Those cases with MICs of greater than 1 microgram/ml did not show a response to penicillin therapy. Of nine patients treated with cefotaxime (200 to 350 mg/kg per day) with penicillin G MICs of 0.1 to 4 micrograms/ml and cefotaxime MICs of less than or equal to 0.03 to 1 microgram/ml, seven recovered, one experienced a relapse after 14 days of therapy and the infection was cured with intravenous vancomycin, and one patient died with sterile cerebrospinal fluid. Thus, adults with meningitis due to penicillin-resistant pneumococci may be adequately treated with high doses (around 300 mg/kg per day) of intravenous cefotaxime if MICs of penicillin G are less than or equal to 4 micrograms/ml. Cases with higher resistance may require another antibiotic such as vancomycin.