Role of cephalosporins in the treatment of bacterial meningitis in adults. Overview with special emphasis on ceftazidime

Comprehensive Therapeutic Approaches to Tuberculous Meningitis: Pharmacokinetics, Combined Dosing, and Advanced Intrathecal Therapies

Tuberculous meningitis (TBM) presents a critical neurologic emergency characterized by high mortality and morbidity rates, necessitating immediate therapeutic intervention, often ahead of definitive microbiological and molecular diagnoses. The primary hurdle in effective TBM treatment is the blood-brain barrier (BBB), which significantly restricts the delivery of anti-tuberculous medications to the central nervous system (CNS), leading to subtherapeutic drug levels and poor treatment outcomes. The standard regimen for initial TBM treatment frequently falls short, followed by adverse side effects, vasculitis, and hydrocephalus, driving the condition toward a refractory state. To overcome this obstacle, intrathecal (IT) sustained release of anti-TB medication emerges as a promising approach. This method enables a steady, uninterrupted, and prolonged release of medication directly into the cerebrospinal fluid (CSF), thus preventing systemic side effects by limiting drug exposure to the rest of the body. Our review diligently investigates the existing literature and treatment methodologies, aiming to highlight their shortcomings. As part of our enhanced strategy for sustained IT anti-TB delivery, we particularly seek to explore the utilization of nanoparticle-infused hydrogels containing isoniazid (INH) and rifampicin (RIF), alongside osmotic pump usage, as innovative treatments for TBM. This comprehensive review delineates an optimized framework for the management of TBM, including an integrated approach that combines pharmacokinetic insights, concomitant drug administration strategies, and the latest advancements in IT and intraventricular (IVT) therapy for CNS infections. By proposing a multifaceted treatment strategy, this analysis aims to enhance the clinical outcomes for TBM patients, highlighting the critical role of targeted drug delivery in overcoming the formidable challenges presented by the blood-brain barrier and the complex pathophysiology of TBM.

Ceftriaxone-induced encephalopathy in a patient with a normal renal function

Ceftriaxone-induced encephalopathy is an exceptionally rare adverse effect of this commonly used cephalosporin and is generally observed in patients undergoing haemodialysis or suffering from severe renal failure. We present a case of a fit woman in her mid-80s with a normal renal function who developed severe fluctuating neurological symptoms (aphasia, loss of contact, chorea-like tongue movements) while being treated with ceftriaxone for a urinary tract infection with bacteraemia. The symptoms began on day 4 of treatment and an adverse drug reaction was suspected on day 7, after exhaustive investigations failed to reveal another cause. A complete recovery was observed 3 days after discontinuing ceftriaxone. Our case highlights the need to consider the diagnosis of ceftriaxone encephalopathy, even if the traditional risk factors are lacking. In this article, we also provide a brief overview of the pathophysiology as well as a literature review concerning the subject.

Clinical Experience with Off-Label Intrathecal Administration of Selected Antibiotics in Adults: An Overview with Pharmacometric Considerations

Drain-associated intracerebral infections are life-threatening emergencies. Their treatment is challenging due to the limited penetration of antibiotics to the site of infection, resulting in potentially inadequate exposure. The emergence of multidrug-resistant pathogens might force the use of off-label intrathecal (IT) doses of antibiotics. We reviewed the literature on general aspects determining intrathecal dosing regimen, using pharmacometric knowledge. We summarised clinical experience with IT doses of antibiotics that are usually not used intrathecally, as well as the outcome of the cases and concentrations reached in the cerebrospinal fluid (CSF). Factors determining the IT regimen are the size of the ventricle system and the CSF drainage volume. With regard to pharmacometrics, pharmacokinetic/pharmacodynamic indices are likely similar to those in non-cerebral infections. The following number (N) of cases were described: benzylpenicillin (>50), ampicillin (1), ceftazidime (2), cephaloridine (56), ceftriaxone (1), cefotiam (1), meropenem (57), linezolid (1), tigecycline (15), rifampicin (3), levofloxacin (2), chloramphenicol (3) and daptomycin (8). Many side effects were reported for benzylpenicillin in the 1940-50s, but for the other antibiotics, when administered correctly, all side effects were minor and reversible. These data might help when choosing an IT dosing regimen in case there is no alternative option due to antimicrobial resistance.

The Blood-Brain Barrier and Pharmacokinetic/Pharmacodynamic Optimization of Antibiotics for the Treatment of Central Nervous System Infections in Adults

Bacterial central nervous system (CNS) infections are serious and carry significant morbidity and mortality. They encompass many syndromes, the most common being meningitis, which may occur spontaneously or as a consequence of neurosurgical procedures. Many classes of antimicrobials are in clinical use for therapy of CNS infections, some with established roles and indications, others with experimental reporting based on case studies or small series. This review delves into the specifics of the commonly utilized antibacterial agents, updating their therapeutic use in CNS infections from the pharmacokinetic and pharmacodynamic perspectives, with a focus on the optimization of dosing and route of administration that have been described to achieve good clinical outcomes. We also provide a concise synopsis regarding the most focused, clinically relevant information as pertains to each class and subclass of antimicrobial therapeutics. CNS infection morbidity and mortality remain high, and aggressive management is critical in ensuring favorable patient outcomes while averting toxicity and upholding patient safety.

Cefazolin versus anti-staphylococcal penicillins for treatment of methicillin-susceptible Staphylococcus aureus bacteraemia: a narrative review

BACKGROUND

Anti-staphylococcal penicillins (ASPs) are recommended as first-line agents in methicillin-susceptible Staphylococcus aureus (MSSA) bacteraemia. Concerns about their safety profile have contributed to the increased use of cefazolin. The comparative clinical effectiveness and safety profile of cefazolin versus ASPs for such infections remain unclear. Furthermore, uncertainty persists concerning the use of cefazolin due to controversies over its efficacy in deep MSSA infections and its possible negative ecological impact.

AIMS

The aim of this narrative review was to gather and balance available data on the efficacy and safety of cefazolin versus ASPs in the treatment of MSSA bacteraemia and to discuss the potential negative ecological impact of cefazolin.

SOURCES

PubMed and EMBASE electronic databases were searched up to May 2017 to retrieve available studies on the topic.

CONTENTS

Although described in vitro and in experimental studies, the clinical relevance of the inoculum effect during cefazolin treatment of deep MSSA infections remains unclear. It appears that there is no significant difference in rate of relapse or mortality between ASPs and cefazolin for the treatment of MSSA bacteraemia but these results should be cautiously interpreted because of the several limitations of the available studies. Compared with cefazolin, there is more frequent discontinuation for adverse effects with ASP use, especially because of cutaneous and renal events. No study has evidenced any change in the gut microbiota after the use of cefazolin.

IMPLICATIONS

Based on currently available studies, there are no data that enable a choice to be made of one antibiotic over the other except in patients with allergy or renal impairment. This review points out the need for future prospective studies and randomized controlled trials to better address these questions.

β-Lactam Therapy for Methicillin-Susceptible Staphylococcus aureus Bacteremia: A Comparative Review of Cefazolin versus Antistaphylococcal Penicillins

Methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia is associated with high morbidity and mortality. Traditionally, antistaphylococcal penicillins (ASPs) have been considered the agents of choice for the treatment of MSSA bacteremia. Vancomycin has been demonstrated to have poorer outcomes in several studies and is only recommended for patients with severe penicillin allergies. Although cefazolin is considered as an alternative to the ASPs for patients with nonsevere penicillin allergies, cefazolin offers several pharmacologic advantages over ASPs, such as more convenient dosing regimens, and antimicrobial stewardship programs are increasingly using cefazolin as the preferential agent for MSSA infections as part of cost-saving initiatives. Concerns about susceptibility to hydrolysis by type A β-lactamases, particularly at high inocula seen in deep-seated infections such as endocarditis; selective pressures from unnecessary gram-negative coverage; and lack of comparative clinical data have precluded recommending cefazolin as a first-line therapy for MSSA bacteremia. Recent clinical studies, however, have suggested similar clinical efficacy but better tolerability, with lower rates of discontinuation due to adverse drug reactions, of cefazolin compared with ASPs. Other variables, such as adequate source control (e.g., intravascular catheter removal, debridement, or drainage) and enhanced pharmacodynamics through aggressive cefazolin dosing, may mitigate the role of cefazolin inoculum effect and factor into determining improved clinical outcomes. In this review, we highlight the utility of cefazolin versus ASPs in the treatment of MSSA bacteremia with a focus on clinical efficacy and safety.

Overton's rule helps to estimate the penetration of anti-infectives into patients' cerebrospinal fluid

In 1900, Ernst Overton found that the entry of anilin dyes through the cell membranes of living cells depended on the lipophilicity of the dyes. The brain is surrounded by barriers consisting of lipid layers that possess several inward and outward active transport systems. In the absence of meningeal inflammation, the cerebrospinal fluid (CSF) penetration of anti-infectives in humans estimated by the ratio of the area under the concentration-time curve (AUC) in CSF (AUC(CSF)) to that in serum (AUC(CSF)/AUC(S)) correlated positively with the lipid-water partition coefficient at pH 7.0 (log D) (Spearman's rank correlation coefficient r(S) = 0.40; P = 0.01) and negatively with the molecular mass (MM) (r(S) = -0.33; P = 0.04). The ratio of AUC(CSF) to the AUC of the fraction in serum that was not bound (AUC(CSF)/AUC(S,free)) strongly correlated with log D (r(S) = 0.67; P < 0.0001). In the presence of meningeal inflammation, AUC(CSF)/AUC(S) also correlated positively with log D (r(S) = 0.46; P = 0.002) and negatively with the MM (r(S) = -0.37; P = 0.01). The correlation of AUC(CSF)/AUC(S,free) with log D (r(S) = 0.66; P < 0.0001) was as strong as in the absence of meningeal inflammation. Despite these clear correlations, Overton's rule was able to explain only part of the differences in CSF penetration of the individual compounds. The site of CSF withdrawal (lumbar versus ventricular CSF), age of the patients, underlying diseases, active transport, and alterations in the pharmacokinetics by comedications also appeared to strongly influence the CSF penetration of the drugs studied.

Penetration of drugs through the blood-cerebrospinal fluid/blood-brain barrier for treatment of central nervous system infections

The entry of anti-infectives into the central nervous system (CNS) depends on the compartment studied, molecular size, electric charge, lipophilicity, plasma protein binding, affinity to active transport systems at the blood-brain/blood-cerebrospinal fluid (CSF) barrier, and host factors such as meningeal inflammation and CSF flow. Since concentrations in microdialysates and abscesses are not frequently available for humans, this review focuses on drug CSF concentrations. The ideal compound to treat CNS infections is of small molecular size, is moderately lipophilic, has a low level of plasma protein binding, has a volume of distribution of around 1 liter/kg, and is not a strong ligand of an efflux pump at the blood-brain or blood-CSF barrier. When several equally active compounds are available, a drug which comes close to these physicochemical and pharmacokinetic properties should be preferred. Several anti-infectives (e.g., isoniazid, pyrazinamide, linezolid, metronidazole, fluconazole, and some fluoroquinolones) reach a CSF-to-serum ratio of the areas under the curves close to 1.0 and, therefore, are extremely valuable for the treatment of CNS infections. In many cases, however, pharmacokinetics have to be balanced against in vitro activity. Direct injection of drugs, which do not readily penetrate into the CNS, into the ventricular or lumbar CSF is indicated when other effective therapeutic options are unavailable.

Strategies and new developments in the management of bacterial meningitis

The principles of antimicrobial therapy for acute bacterial meningitis include use of agents that penetrate well into cerebrospinal fluid and attain appropriate cerebrospinal fluid concentrations, are active in purulent cerebrospinal fluid, and are bactericidal against the infecting pathogen. Recommendations for treatment of bacterial meningitis have undergone significant evolution in recent years, given the emergence of pneumococcal strains that are resistant to penicillin. Clinical experience with use of newer agents is limited to case reports, but these agents may be necessary to consider in patients who are failing standard therapy.

Management of meningitis due to antibiotic-resistant Acinetobacter species

Acinetobacter meningitis is becoming an increasingly common clinical entity, especially in the postneurosurgical setting, with mortality from this infection exceeding 15%. Infectious Diseases Society of America guidelines for therapy of postneurosurgical meningitis recommend either ceftazidime or cefepime as empirical coverage against Gram-negative pathogens. However, assessment of the pharmacodynamics of these cephalosporins in cerebrospinal fluid suggests that recommended doses will achieve pharmacodynamic targets against fewer than 10% of contemporary acinetobacter isolates. Thus, these antibiotics are poor options for suspected acinetobacter meningitis. From in vitro and pharmacodynamic perspectives, intravenous meropenem plus intraventricular administration of an aminoglycoside may represent a superior, albeit imperfect, regimen for suspected acinetobacter meningitis. For cases of meningitis due to carbapenem-resistant acinetobacter, use of tigecycline is not recommended on pharmacodynamic grounds. The greatest clinical experience rests with use of polymyxins, although an intravenous polymyxin alone is inadvisable. Combination with an intraventricularly administered antibiotic plus removal of infected neurosurgical hardware appears the therapeutic strategy most likely to succeed in this situation. Unfortunately, limited development of new antibiotics plus the growing threat of multidrug-resistant acinetobacter is likely to increase the problems posed by acinetobacter meningitis in the future.

Nosocomial bacterial meningitis, including central nervous system shunt infections

Nosocomial bacterial meningitis and CSF shunt infections result in considerable morbidity and mortality, necessitating an organized and thoughtful approach to prevention, diagnosis, and management. Prophylactic antibiotics appear to reduce the rate of postcraniotomy meningitis often caused by S. aureus. On the other hand, prophylactic antibiotics do not appear to reduce the risk of developing a CSF shunt infection. CSF shunt infections usually require shunt removal and antimicrobial chemotherapy to effect a successful outcome.

Pharmacokinetic optimisation of the treatment of bacterial central nervous system infections

Central nervous system (CNS) infections caused by bacteria with reduced sensitivity to antibacterials are an increasing worldwide challenge. In successfully treating these infections the following conditions should be considered: (i) Antibacterials do not distribute homogeneously in the central nervous compartments [cerebrospinal fluid (CSF), extracellular space of the nervous tissue, intracellular space of the neurons, glial cells and leucocytes]. Even within the CSF, after intravenous administration, a ventriculo-lumbar concentration gradient is often observed. (ii) Valid parameters of drug entry into the CSF are the CSF: serum concentration ratio in steady state and the CSF: serum ratio of the area under the concentration-time curves (AUCCSF/AUCS). Frequently, the elimination half-life (t1/2 beta) in CSF is longer than t1/2 beta in serum. (iii) For most antibacterials, lipophilicity, molecular weight and serum protein binding determine the drug entry into the CSF and brain tissue. With an intact blood-CSF and blood-brain barrier, the entry of hydrophilic antibacterials (beta-lactam antibacterials, glycopeptides) into the CNS compartments is poor and increases during meningeal inflammation. More lipophilic compounds [metronidazole, quinolones, rifampicin (rifampin) and chloramphenicol] are less dependent on the function of the blood-CSF and blood-brain barrier. (iv) Determination of the minimal inhibitory concentrations (MIC) of the causative organism is necessary for optimisation of treatment. (v) For rapid sterilisation of CSF, drug concentrations of at least 10 times MIC are required. The minimum CSF concentration: MIC ratio ensuring successful therapy is unknown. Strategies to achieve optimum antibacterial concentrations in the presence of minor disturbances of the blood-CSF and blood-brain barrier include, the increased use of low toxicity antibacterials (e.g., beta-lactam antibiotics), the use of moderately lipophilic compounds, and the combination of intravenous and intraventricular administration. Antibacterials which do not interfere with bacterial cell wall synthesis delay and/or decrease the liberation of proinflammatory bacterial products, delay or inhibit tumour necrosis factor release, and may reduce brain oedema in experimental meningitis. Conclusive evidence of the reduction of neuronal damage by this approach, however, is lacking.

Antimicrobial agents for the dermatologist. I. Beta-lactam antibiotics and related compounds

We review the newer antimicrobial agents that are being employed by dermatologists with increased frequency as well as some of the more commonly used older agents. Particular emphasis is based on selection factors such as causative pathogens and their resistance profiles, routes of administration, toxicity, drug interactions, and dosing requirements. Emphasis in this review is on the newer classes of antimicrobials such as third- and fourth-generation cephalosporins; beta-lactam, beta-lactamase inhibitor combination agents; monobactams; carbapenems; macrolides; and fluoroquinolones. Dermatologic indications and treatment alternatives are highlighted; this will expand the practicing clinician's therapeutic armamentarium and enable him/her to make rational decisions concerning treatment approaches to infectious disease problems encountered in daily practice.

Cerebrospinal fluid ceftazidime kinetics in patients with external ventriculostomies

Ceftazidime has proven to be effective for the treatment of bacterial meningitis caused by multiresistant gram-negative bacteria. Since nosocomial central nervous system infections are often accompanied by only a minor dysfunction of the blood-cerebrospinal fluid (CSF) barrier, patients with noninflammatory occlusive hydrocephalus who had undergone external ventriculostomy were studied (n = 8). Serum and CSF were drawn repeatedly after the administration of the first dose of ceftazidime (3 g over 30 min intravenously), and concentrations were determined by high-performance liquid chromatography by using UV detection. The concentrations of ceftazidime in CSF were maximal at 1 to 13 h (median, 5.5 h) after the end of the infusion and ranged from 0.73 to 2.80 mg/liter (median, 1.56 mg/liter). The elimination half-lives were 3.13 to 18.1 h (median, 10.7 h) in CSF compared with 2.02 to 5.24 h (median, 3.74 h) in serum. The ratios of the areas under the concentration-time curves in CSF and serum (AUCCSF/AUCS) ranged from 0.027 to 0.123 (median, 0.054). After the administration of a single dose of 3 g, the maximum concentrations of ceftazidime in CSF were approximately four times higher than those after the administration of 2-g intravenous doses of cefotaxime (median, 0.44 mg/liter) and ceftriaxone (median, 0.43 mg/liter) (R. Nau, H. W. Prange, P. Muth, G. Mahr, S. Menck, H. Kolenda, and F. Sörgel, Antimicrob. Agents Chemother. 37:1518-1524, 1993). The median AUCCSF/AUCS ratio of ceftazidime was slightly below that of cefotaxime (0.12), but it was 1 order of magnitude above the median AUCCSF/AUCS of ceftriaxone (0.007) (Nau et al., Antimicrob. Agents Chemother. 37:1518-1524, 1993). The concentrations of ceftazidime observed in CSF were above the MICs for most Pseudomonas aeruginosa strains. However, they are probably not high enough to be rapidly bactericidal. For this reason, the daily dose should be increased to 12 g in cases of P. aeruginosa infections of the central nervous system when the blood-CSF barrier is minimally impaired.

Third-generation cephalosporins

Third-generation cephalosporins are broad-spectrum antimicrobial agents useful in a variety of clinical situations. No one cephalosporin is appropriate for all infectious disease problems. Cefotaxime and ceftizoxime have the best gram-positive coverage of the third-generation agents. Ceftazidime and cefoperazone are the only third-generation drugs that provide antipseudomonal coverage. Ceftriaxone's long half-life allows for once-daily dosing, making ceftriaxone an excellent drug for outpatient antibiotic therapy of community-acquired infections. Ceftriaxone is also useful for the treatment of Lyme disease and sexually transmitted diseases. The third-generation cephalosporins except for cefoperazone penetrate cerebrospinal fluid and are indicated for the treatment of bacterial meningitis. Their proven record of clinical efficacy, favorable pharmacokinetics, and low frequency of adverse effects make third-generation cephalosporins the preferred antibiotic in many clinical situations.

Nosocomial epiglottitis associated with penicillin- and cephalosporin-resistant Streptococcus pneumoniae bacteremia

We cared for a 4-year-old male with nosocomially acquired epiglottitis caused by Streptococcus pneumoniae. He had been receiving ceftazidime therapy when this infection was recognized. The S. pneumoniae isolate was of serotype 15B and was resistant to beta-lactam antibiotics, cephalosporins (including those with extended spectra), and trimethoprim-sulfamethoxazole. Clinicians and clinical microbiologists must be aware that cephalosporin susceptibility may no longer be assumed for penicillin-resistant S. pneumoniae isolates and that susceptibility testing for the extended-spectrum cephalosporins should be performed whenever this species is isolated from a normally sterile body fluid.

A comparison of ceftazidime and aminoglycoside based regimens as empirical treatment in 1316 cases of suspected sepsis in the newborn. European Society for Paediatric Infectious Diseases--Neonatal Sepsis Study Group

We report a prospective, non-blind, randomised, multicentre, parallel group, multinational investigation to compare ceftazidime to aminoglycoside based regimens as empirical treatment in 1316 cases of suspected sepsis in the newborn. In each of the 15 study centres either ceftazidime alone (CAZ) or ceftazidime + ampicillin (CAZ + AMP) was compared to an amino-glycoside/ampicillin combination (AG + AMP). In all cases treatment was based on "an intention to treat". Bacteria considered to be pathogenic were isolated from 176/1316 (13.4%) patients. The incidence of proven infection varied from 39% in a Yugoslav centre to 6% in a British centre; a further 489/1316 (37.1%) patients fulfilled the criteria for clinically suspected sepsis. A total of 210 bacterial isolates from 197 infection sites in 176 patients were considered to be clinically significant. The cure rate for evaluable patients with proven infection who were treated with CAZ + AMP (97%, 30/31) was significantly higher than that for the corresponding patients treated with AG + AMP (66%, 26/39), (P < 0.002). The difference in cure rate between CAZ monotherapy (79%, 34/43) and AG + AMP (86%, 32/37) was not significant. Treatment failed in 28/150 (18.7%) evaluable patients. There were significantly fewer failures (P < 0.001) with CAZ + AMP than with AG + AMP therapy. There were 55 staphylococcal infections. Treatment was successful in 16/19 evaluable patients treated with CAZ or CAZ + AMP and in 16/29 evaluable patients treated with AG + AMP. None of the study centres encountered problems with ceftazidime resistant bacteria. The cure rate for patients with only clinical and radiological evidence of sepsis was greater than 94% in all treatment groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetics and tissue concentrations of cefuroxime

Cefuroxime is well-absorbed and distributed over the human body. This review gives a general summary of published information on tissue concentrations of cefuroxime after an intravenous or intramuscular dose of 750 or 1,500 mg of cefuroxime. Tissue concentrations are given for blister fluid, meninges, eyes, respiratory tract, sputum and bronchi, abdominal and urogenital tract, uterine, ovarian and fallopian tube tissue, myometrium, membranes, placenta, puruloid and healthy human milk, bile, prostate, hip and knee bone. Pharmacokinetics are reviewed in patients with impaired kidney function and in pregnancy.

Third-generation cephalosporins in the treatment of rare infections

This article reviews the published clinical experience of the use of the third-generation cephalosporins in the treatment of rare infections. Rare infections are defined as those caused by unusual pathogens or multi-resistant organisms as well as those occurring in unusual or pharmacologically protected body sites. Examples of such infections are uncommon causes of meningitis and ventriculitis, brain abscess, rare causes of bacterial endocarditis, metastatic Salmonella infections, spontaneous bacterial peritonitis and liver abscess, late complications of Lyme borreliosis, uncommon Pseudomonas infections, and post-reconstructive surgery Aeromonas cellulitis. Although these data are largely anecdotal, they form a useful body of information, providing guidance on the management of similar problems encountered by other doctors, while suggesting areas of further investigation for the management of a variety of unusual infections with the third-generation cephalosporins.

Empiric therapy of severe infections in adults

The third-generation cephalosporins are useful for empiric therapy of most of the severe infections in adults as a result of their broad spectrum of antimicrobial activity (particularly against clinically important gram-negative bacteria), good tissue penetration, and lack of serious adverse effects. This review examines their use in respiratory tract infections, bacterial meningitis, skin-structure infections, and urinary tract infections in adult patients. Penicillin G remains the optimal therapy for severe community-acquired pneumonia, since Streptococcus pneumoniae still accounts for the majority of cases. However, for empiric treatment of nosocomial pneumonia, therapy must ensure coverage both of aerobic gram-negative bacilli and Staphylococcus aureus. The choice of empiric antibiotic therapy in the treatment of urinary tract infections depends on the pattern of resistance in the patient's environment. At present, the treatment of bacterial meningitis in otherwise healthy adults does not constitute a major problem provided that penicillin resistance among pneumococci and meningococci (responsible for at least 80 percent of cases) does not become a clinical problem. However, in meningitis in which gram-negative bacilli are suspected and where specific problems include antibiotic resistance among these organisms and the inadequate penetration of many antibiotics into the cerebrospinal fluid, third-generation cephalosporins are the drugs of choice, and they have markedly improved the clinical outcome. Most skin-structure infections are due to S. aureus and are best treated by an anti-staphylococcal penicillin or an older cephalosporin. Nevertheless, the third-generation cephalosporins have proved to be highly effective agents for infections of skin and soft-tissue infections associated with both gram-positive and gram-negative pathogens in patients at risk from these organisms or in the elderly.

Antimicrobial agents: the old and the new

Although there are many new antimicrobial agents, many of the old antibiotics are still useful in the treatment of infections, particularly those in the community. Antimicrobial resistance patterns and special pharmacologic properties should influence the selection of newer antimicrobial agents. Change from parenteral therapy to oral therapy should increase to avoid the complications of intravenous therapy and to reduce hospital costs. Older antibiotics that are less costly should be used when the etiology and susceptibility of infecting pathogens are known. There will continue to be new antibiotics produced. Understanding the microbiologic and pharmacologic advantages of the new agents compared with older agents is essential if the new agents are to be used properly and not destroyed by inappropriate use.

Treatment of childhood bacterial meningitis

One hundred and eighty-seven children with identified bacterial meningitis were treated with intravenous cefotaxime: 15 patients were neonates, 79 infants, and 93 were aged from 1 to 14 years. Causative organisms were: Neisseria meningitidis in 80 cases, Streptococcus pneumoniae in 41, Haemophilus influenzae in 40, enteric gram-negative bacilli in 20 and Staphylococcus spp. in six. Enteric gram-negative bacilli included: Salmonella spp. in 14 cases, Klebsiella pneumoniae in two, and Escherichia coli, Enterobacter sakazakii and Acinobacter calcoaceticus in one each; in one case the organism was not specified. Daily dose of cefotaxime was 150 to 300 mg/kg. Concomitant treatment with an aminoglycoside was used in seven cases. One hundred and seventy-two patients (92.0%) were cured. Fever persisted for a mean of five days and meningeal signs for a mean of four days. Fifteen (8.0%) patients died: most [13] of them were admitted in coma, and two in shock. Death occurred in the first 48 h in ten cases. Sterilization of CSF was achieved in the first 72 h of treatment in 155 (90.1%) of the cured patients. Cefotaxime was well tolerated. CSF penetration of cefotaxime was evaluated in seven patients: concentrations ranged from 0.499 mg/l to 2.829 mg/l. Based on this clinical study, cefotaxime is an effective and safe drug for the treatment of childhood bacterial meningitis.

[Rational parameters in the treatment of bacterial meningitis with modern cephalosporins]

Modern cephalosporins are by now well established therapeutic drugs in the treatment of bacterial meningitis. Particularly for gram-negative meningitis they are valuable therapeutic tools. In most cases, they are very efficient and less toxic than former therapeutic regimens. Of course, they cannot replace penicillin G in the therapy of meningitis with penicillin-sensitive bacteria. The advantages and disadvantages of the single compounds, cefotaxime, latamoxef, ceftizoxime, cefmenoxime, ceftazidime, ceftriaxone and cefsulodin have to be evaluated. For safety reasons, monotherapy with these drugs is not recommended because there have been reports of failures and relapses of meningitis even in cases with highly sensitive organisms. They are almost or completely ineffective against a few pathogens in meningitis, such as anaerobes or Listeria monocytogenes. An attempt has been made to evaluate the different compounds for their therapeutic usefulness against different pathogens in meningitis.

Antibiotics in the second half of the 1980s. Areas of future development and the effect of new agents on aminoglycoside use

Articles in this supplement have examined in detail the role of aminoglycosides in the therapy of infections, addressing problems of resistance, toxicity, and efficacy. This article discusses other agents and their potential utility and effect on aminoglycosides. Penem antibiotics, which have activity against only aerobic gram-negative bacteria, have recently been synthesized. These agents have proved effective in animal experiments; to date, however, results of human clinical trials are not available. Carboxypenicillins and ureidopenicillins will still have to be administered with aminoglycosides in patients with serious life-threatening infections or in those institutions in which organisms such as Klebsiella, Enterobacter, and Pseudomonas exhibit high levels of resistance. What will be the role of aminothiazolyl cephalosporins? In some institutions, these agents might be used as sole therapy, particularly if they become less costly as a result of competition. In other settings, concern over the resistance of organisms, such as Enterobacter cloacae, Citrobacter freundii, Serratia marcescens, and Pseudomonas aeruginosa, will result in the use of aminoglycosides with these relatively beta-lactamase-stable cephalosporins. It will be necessary to monitor the development of resistance to the new antibiotics and to determine whether the use of aminoglycosides plus third-generation cephalosporin combinations results in decreased resistance. Other agents to be considered include the directed therapy monobactams aztreonam and carumonam, the broad-spectrum carbapenem imipenem, and the penems under development. It is unclear whether these compounds might be used with aminoglycosides in critically ill, infected patients. It is also unclear what role oral beta-lactamase-stable cephalosporins will have in the therapy of nosocomial infections, since they probably will not be effective against many of the urinary or cutaneous infections that are treated with aminoglycosides. Quinolone agents can be used successfully against many infections. However, the likelihood of bacterial resistance developing and their potential for toxicity are still unknown. Thus, despite the emergence of many new agents, it appears that the time-tested aminoglycosides will continue to play an important role in antimicrobial therapy for some time to come.

Post-neurosurgical and spontaneous gram-negative bacillary meningitis in adults

In order to evaluate the clinical aspects of gram-negative bacillary meningitis (GNBM) we reviewed the charts of 20 adult patients with the discharge diagnosis of meningitis caused by gram-negative bacilli (bacteriologically proved) seen between 1973 and 1984. Nine patients had post-neurosurgical (post-NS) GNBM and 11 patients spontaneous (S) GNBM; the mean age of the former was 42 +/- 16 years and of the latter 56 +/- 14 years (p less than 0.05). The overall mortality rate was 50% (33% in the post-NS group and 64% in the S group). The glucose levels in CSF were significantly lower in the patients who died. Patients treated with combined aminoglycoside therapy presented a lower mortality rate than those treated with intravenous aminoglycoside only (25% versus 70%). We suggest that if aminoglycoside therapy is employed, these antibiotics must be administered both intravenously and directly into CNS.