Past and current roles for cephalosporin antibiotics in treatment of meningitis. Emphasis on use in gram-negative bacillary meningitis

Effect of ketoprofen and tolfenamic acid on intravenous pharmacokinetics of ceftriaxone in sheep

In this study, the pharmacokinetics of ceftriaxone (40 mg/kg) was determined following a single intravenous (IV) administration of ceftriaxone alone and co-administration with ketoprofen (3 mg/kg) or tolfenamic acid (2 mg/kg) in sheep. Eight healthy Akkaraman sheep (2.4 ± 0.3 years and 44 ± 4 kg of body weight) were used. The study was carried out according to the longitudinal design in three periods with a 15-day washout period between administrations. In the first period, sheep received ceftriaxone alone via an IV injection. In the second and third periods, the same sheep received ceftriaxone in combination with ketoprofen and tolfenamic acid, respectively. Plasma concentrations of ceftriaxone were assayed by high-performance liquid chromatography and analyzed using non-compartmental analysis. Following the administration of ceftriaxone alone, the elimination half-life (t_1/2ʎz ), area under the plasma concentration-time curve from zero (0) hours to infinity (∞) (AUC_0-∞ ), total clearance (Cl_T ), and volume of distribution at steady state were 1.42 h, 182.41 h*µg/ml, 0.22 L/h/kg, and 0.17 L/kg, respectively. While ketoprofen and tolfenamic acid significantly increased the t_1/2ʎz and AUC_0-∞ of ceftriaxone, they significantly reduced the Cl_T . Ceftriaxone (40 mg/kg, IV) in concurrent use with ketoprofen and tolfenamic acid can be administrated at the 12 h dosing intervals to maintain T> minimum inhibitory concentration (MIC) values above 60% in the treatment of infections caused by susceptible pathogens with the MIC value of ≤0.75 and ≤1 μg/mL, respectively, in sheep with an inflammatory condition.

Adults with spontaneous aerobic Gram-negative bacillary meningitis admitted to the intensive care unit

The characteristics of spontaneous aerobic Gram-negative bacillary meningitis (AGNBM) were determined in 40 adults requiring admission to an intensive care unit (ICU) during a 16-year period in ten French ICUs. Eight infections were hospital-acquired and most patients had predisposing factors, mainly chronic alcoholism and an immunocompromised status. Three immunosuppressed patients had disseminated strongyloidiasis. Gram's stain, cerebrospinal fluid and blood cultures were positive for 85%, 98% and 80% of cases, respectively. Escherichia coli (57%) and Klebsiella pneumoniae (17%) were the most frequent pathogens. In-ICU mortality was 38%. Spontaneous AGNBM is a rare complication of bacteraemia in adults. The severity of predisposing underlying diseases might explain the poor prognosis despite appropriate antimicrobial therapy.

Cefotaxime acts synergistically with levofloxacin in experimental meningitis due to penicillin-resistant pneumococci and prevents selection of levofloxacin-resistant mutants in vitro

Cefotaxime, given in two doses (each 100 mg/kg of body weight), produced a good bactericidal activity (-0.47 Deltalog(10) CFU/ml. h) which was comparable to that of levofloxacin (-0.49 Deltalog(10) CFU/ml. h) against a penicillin-resistant pneumococcal strain WB4 in experimental meningitis. Cefotaxime combined with levofloxacin acted synergistically (-1.04 Deltalog(10) CFU/ml. h). Synergy between cefotaxime and levofloxacin was also demonstrated in vitro in time killing assays and with the checkerboard method for two penicillin-resistant strains (WB4 and KR4). Using in vitro cycling experiments, the addition of cefotaxime in sub-MIC concentrations (one-eighth of the MIC) drastically reduced levofloxacin-induced resistance in the same two strains (64-fold increase of the MIC of levofloxacin after 12 cycles versus 2-fold increase of the MIC of levofloxacin combined with cefotaxime). Mutations detected in the genes encoding topoisomerase IV (parC and parE) and gyrase (gyrA and gyrB) confirmed the levofloxacin-induced resistance in both strains. Addition of cefotaxime in low doses was able to suppress levofloxacin-induced resistance.

Phenytoin pharmacokinetics and clinical effects in African children following fosphenytoin and chloramphenicol coadministration

AIMS

Some children with malaria and convulsions also have concurrent bacterial meningitis. Chloramphenicol is used to treat the latter whereas phenytoin is used for convulsions. Since chloramphenicol inhibits the metabolism of phenytoin in vivo, we studied the effects of chloramphenicol on phenytoin pharmacokinetics in children with malaria.

METHODS

Multiple intravenous (i.v.) doses of chloramphenicol succinate (CAP) (25 mg kg-1 6 hourly for 72 h) and a single intramuscular (i.m.) seizure prophylactic dose of fosphenytoin (18 mg kg-1 phenytoin sodium equivalents) were concomitantly administered to 15 African children with malaria. Control children (n = 13) with malaria received a similar dose of fosphenytoin and multiple i.v. doses (25 mg kg-1 8 hourly for 72 h) of cefotaxime (CEF). Blood pressure, heart rate, respiratory rate, oxygen saturation, level of consciousness and convulsion episodes were monitored. Cerebrospinal fluid (CSF) and plasma phenytoin concentrations were determined.

RESULTS

The area under the plasma unbound phenytoin concentration-time curve (AUC(0, infinity ); means (CAP, CEF): 58.5, 47.6 micro g ml-1 h; 95% CI for difference between means: -35.0, 11.4), the peak unbound phenytoin concentrations (Cmax; medians: 1.12, 1.29 micro g ml-1; 95% CI: -0.5, 0.04), the times to Cmax (tmax; medians: 4.0, 4.0 h; 95% CI: -2.0, 3.7), the CSF:plasma phenytoin ratios (means: 0.21, 0.22; 95% CI: -0.8, 0.10), the fraction of phenytoin unbound (means: 0.06, 0.09; 95% CI: -0.01, 0.07) and the cardiovascular parameters were not significantly different between CAP and CEF groups. However, mean terminal elimination half-life (t1/2,z) was significantly longer (23.7, 15.5 h; 95% CI: 1.71, 14.98) in the CAP group compared with the CEF group. Seventy per cent of the children had no convulsions during the study period.

CONCLUSIONS

Concomitant administration of chloramphenicol and a single i.m. dose of fosphenytoin alters the t1/2,z but not the other pharmacokinetic parameters or clinical effects of phenytoin in African children with severe malaria. Moreover, a single i.m. dose of fosphenytoin provides anticonvulsant prophylaxis in the majority of the children over 72 h. However, a larger study would be needed to investigate the effect of concomitant administration of multiple doses of the two drugs in this population of patients.

Gram-negative bacillary meningitis in adult post-neurosurgical patients

BACKGROUND

To assess the clinical features and therapeutic outcomes of gram-negative bacillary meningitis (GNBM) in adult postneurosurgical patients.

METHODS

Thirty adult patients with GNBM were included in this study. Their clinical features, laboratory data, prognostic factors, and therapeutic outcome were analyzed. The patients were 22 males and 8 females, aged 17-72 years. Seven had community-acquired infections and 23 had nosocomial infections. Two patients were associated with brain abscess.

RESULTS

The pathogens found in the 30 GNBM patients were Pseudomonas aeruginosa, Klebsiella species, Escherichia coli, Acinetobacter baumannii, and some rare pathogens including Citrobacter freundii, Serratia marcescens, Enterobacter cloacae, and Proteus mirabilis. Among these 30 patients, 8 patients with third-generation cephalosporin-resistant GNBM were identified since 1994; all infections were nosocomially acquired. Appropriate antibiotics were given to 22 patients. Eight patients did not receive appropriate antibiotic therapy. All eight died. The mortality rate in those treated with appropriate antibiotics was 14%.

CONCLUSIONS

There has been an increase of GNBM in postneurosurgical patients in recent years. In addition, the emergence of strains resistant to third-generation cephalosporins in this specific group of patients has also been noted in recent years, and has become a great therapeutic challenge. We noted many prognostic factors in postneurosurgical patients in this study; however, appropriate antibiotic therapy and initial consciousness level are the most significant ones. Therefore, in cases of postneurosurgical patients with nosocomially acquired GNBM, the possibility of third-generation cephalosporin resistance should be strongly suspected. Early initiation of appropriate antibiotic therapy is needed in this potentially fatal disease.

The prognostic factors of adult gram-negative bacillary meningitis

Seventy-seven patients with Gram-negative bacillary meningitis (GNBM), 57 males and 20 females, aged 17-86 years, were identified at Kaohsiung Chang Gung Memorial Hospital, over an 11-year period. Fifty-four infections were community-acquired, and 23 were nosocomial; 49 were spontaneous and 28 occurred after head surgery or neurosurgery. The organisms most frequently involved were Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli, and Acinetobacter. Rarer pathogens included Citrobacter species, Serratia marcescens, Enterobacter cloacae, and Proteus mirabilis. All patients who did not receive appropriate antibiotic therapy died. The mortality in those treated with appropriate antibiotics was 28%. Other statistically significant prognostic factors included septic shock, initial level of consciousness, hyperosmolar hyperglycemic nonketotic coma, disseminated intravascular coagulation, high cerebrospinal fluid lactate levels and leucocytosis. In the multiple logistic regression analysis, only appropriate antimicrobial therapy and septic shock were strongly associated with mortality even after adjusting for other potentially confounding factors. Despite the high mortality, management can be improved by early diagnosis, early use of appropriate antibiotics, and correction of underlying and associated medical derangement.

Update on the use of cefotaxime for pediatric meningitis in Portugal

We treated 256 children who had identified bacterial meningitis with cefotaxime. Causative organisms were: Neisseria meningitidis in 108 cases, Streptococcus pneumoniae in 61, Haemophilus influenzae in 60, enteric Gram-negative bacilli in 21, and Staphylococcus spp. in six. Daily doses of cefotaxime were 150-200 mg/kg. A total of 240 patients (93.7%) were cured. In the cured patients, sterilization of cerebrospinal fluid was obtained in the first 72 h of treatment in 214 (80.0%). Cefotaxime is an effective and safe drug for the treatment of childhood bacterial meningitis.

Citrobacter meningitis in adults

Citrobacter meningitis is an uncommon infection of neonates and young children. It is rarely seen in adults. We describe a 46-year-old man with a mixed bacterial meningitis caused by C. diversus and Klebsiella oxytoca and a 64-year-old woman with C. freundii meningitis. Review of the English-language literature revealed only 2 adult patients with C. diversus meningitis and another 2, with C. freundii meningitis. The ages of these 6 aforementioned patients ranged from 31 to 84 years. Multiple facial fractures, neurosurgical procedures, alcoholism and diabetes mellitus were predisposing conditions. Among the 5 patients whose outcome was known, antibiotic therapy was successful in 4 but failed in 1. This study emphasizes that almost any of the gram-negative bacilli can cause serious infection of the central nervous system in adults in the proper setting.

Klebsiella pneumoniae meningitis: prognostic factors

All 42 cases of Klebsiella pneumoniae meningitis diagnosed between 1981 and 1991 were evaluated. These accounted for 13% of patients with blood and/or cerebrospinal fluid culture-proven bacterial meningitis. There was an increased incidence of K. pneumoniae meningitis from the first 6 years of study (7%) to the last 5 years (16%). K. pneumoniae became increasingly important not only in community-acquired meningitis but also in nosocomial meningitis. 12/13 nosocomial cases were patients who had undergone neurosurgical procedures. The overall mortality rate was 43%. The mortality rate in patients with spontaneous meningitis was higher than that in patients with post-traumatic or postoperative meningitis. Factors that adversely affected mortality were age over 60, diabetes mellitus, and severe neurological deficits on admission. The use of third-generation cephalosporins did not reduce the mortality rate.

Klebsiella ozaenae meningitis: report of two cases and review of the literature

Meningitis is rarely caused by Klebsiella ozaenae, a colonizer of the oral and nasopharyngeal mucosa. We describe two patients with K. ozaenae meningitis. Both patients suffered from a primary disease of the nasopharyngeal pathway; one had nasopharyngeal carcinoma and the other ozena. Review of the English-language literature from 1966 to the present revealed only two cases of K. ozaenae meningitis; pneumonia and hyperglycemia were noted in one patient and otitis media, sinusitis and diabetes mellitus in the other. All these four patients were over 50 years old. Of the four patients, two treated with third-generation cephalosporins recovered whereas one of the two treated with chloramphenicol died. One patient who died had a positive blood culture for K. ozaenae. Blood culture was positive in only one of the three survivors. Whether chloramphenicol should be replaced by a third-generation cephalosporin and whether blood culture indicates a poor prognosis in K. ozaenae meningitis remain to be determined.

Acute Therapy of Bacterial Meningitis

Antimicrobial therapy for bacterial meningitis has markedly reduced mortality rates from this disorder. The efficacy of an antibiotic in meningitis depends on many factors, including its penetration into cerebrospinal fluid (CSF), the bactericidal efficacy of the antibiotic within purulent CSF, and the need for bactericidal activity in CSF because bacterial meningitis represents an infection in an area of impaired host defense. Penicillin G and ampicillin are equally efficacious for meningitis caused by Streptococcus pneumoniae or Neisseria meningitidis. This recommendation may change, however, with the emergence of strains of pneumococci or meningococci that are relatively or highly resistant to penicillin; a third-generation cephalosporin (cefotaxime or ceftriaxone) should be used for meningitis due to relatively resistant strains and vancomycin for pneumococcal meningitis caused by strains that are highly resistant to penicillin. With the high percentage of strains of Haemopbilus influenzae type b that produce β-lactamase, empiric therapy when this organism is suspected should consist of a third-generation cephalosporin; these agents are also used for meningitis caused by enteric gram-negative bacilli, and one agent, ceftazidime, is effective against Pseudomonas aeruginosa meningitis. Despite the availability of effective bactericidal antibiotics, morbidity and mortality from bacterial meningitis remains unacceptably high. Recent studies using animal models of infection have demonstrated the beneficial effect of antiinflammatory agents in attenuating the CSF inflammatory response that may lessen many of the pathophysiological consequences of meningitis. Studies of adjunctive dexamethasone therapy suggest that these agents may reduce morbidity (specifically sensorineural hearing loss) and mortality (due to S. pneumoniae) in patients with bacterial meningitis. Controversy remains, however, concerning the use of dexamethasone in all patients with bacterial meningitis and further studies are necessary. In critically ill patients with bacterial meningitis, control of increased intracranial pressure and seizures may be useful and necessary in improving outcome.

Pharmacological properties of cephalosporins

The cephalosporins differ in the substituents attached at the 3 and/or 7 positions of the molecule. Very schematically, substitution at C3 mainly modifies the overall pharmacokinetic properties whereas substitution at position 7 influences the antibacterial characteristics. When using the more common "generation" system for classification, three generations can be distinguished on the basis of their antibacterial spectrum, potency, and their stability to beta-lactamases. The first generation cephalosporins have similar antibacterial and pharmacokinetic characteristics. C3-esterified cephalosporins (e.g. cephalothin and cephapirin) are significantly metabolized. The so-called second generation cephalosporins exhibit only minor differences with respect to the pharmacokinetic properties in contrast to the third generation cephalosporins. The apparent volumes of distribution of most cephalosporins range between seven and 20 1, indicating that they mainly stay in the extracellular space. Plasma protein binding is variable from compound to compound. Generally, the major route of elimination of most cephalosporins is via the kidney except for cefoperazone and ceftriaxone which are both excreted to a large extent by the biliary route. With the exception of cefonicid, cefotetan and cefriaxone, which have longer elimination half-lives (i.e. 4.5, 3.5 and around eight hours), all other cephalosporins have a half-life ranging from 0.5 to 2.5 hours. The pattern of adverse reactions is comparable for all the cephalosporins although there are slight differences in both the incidence and the type of reactions. The major categories of adverse reactions are gastrointestinal, dermatologic, hypersensitivity, haematologic, hepatic, renal as well as CNS effects. Alcohol intolerance (antabus-like effect) can occur when cephalosporins containing the NMTT moiety are administered concomitantly.(ABSTRACT TRUNCATED AT 250 WORDS)

Short course single daily ceftriaxone monotherapy for acute bacterial meningitis in children: results of a Swiss multicenter study. Part I: Clinical results

In a prospective Swiss multicenter study, 119 children (aged three weeks to 15.5 years) with acute bacterial meningitis were treated with single daily doses of ceftriaxone (100 mg/kg on days one and two and 60 mg/kg thereafter). All patients were randomly assigned to either short course (four, six, seven days) or full course (eight, 12, 14 days) therapy depending on whether they had contracted meningococcal, Haemophilus influenzae type b or pneumococcal meningitis. Bacteriological cure was obtained in 92 children who fully completed the study and in all the 20 culture-positive of the 27 children secondarily excluded from the study for failure to meet all bacteriological and initial safety criteria for continuation in protocol (secondary exclusions). Complete clinical recovery was noted in 105 of 119 patients (88%) and was as frequent in the short course (91%) as in the full course (89%), and as in the secondary exclusion (81%) group. All patients survived. At follow-up examination three to six months after hospital discharge only seven infants and seven children (11.8%), mostly those with poor presentation on admission (p = 0.0012), showed residual neurological sequelae. Side effects of antibiotic therapy were minor but more frequent, albeit not statistically significant (p = 0.065), in children receiving the full course therapy. The results of this study suggest that short course treatment of acute bacterial meningitis in children with single daily ceftriaxone monotherapy is as efficacious as full course therapy and at least as well tolerated.

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.

Choosing cephalosporins for the formulary

Proper selection of antibiotics for any formulary requires cooperation and communication with members of the pharmacy and therapeutics (P&T) committee and departments of infectious diseases, microbiology, and epidemiology. Ideally, P&T members need to know their institution's incidence and sources of infection (hospital- or community-acquired), antibiotic cure rates, and the adverse effects profiles of antimicrobial agents used. In addition, members need to be briefed on the findings of antibiotic utilization reviews performed. In vitro activity should be compared among similar classes of antibiotics and, when possible, local resistance rates should be considered. The pharmacokinetic properties of an antibiotic, such as peak concentration, protein binding, distribution characteristics, and elimination half-life, should be evaluated during the selection process, as should total cost of the drug, including costs associated with monitoring therapy. The three generations of cephalosporins are used as examples here to delineate differences in potency, pharmacokinetics, efficacy, and potential for causing adverse reactions during the ideal formulary evaluation process.

Inflammatory disease of the central nervous system

Inflammatory diseases involving the central nervous system can be difficult to diagnose and frustrating to treat. The clinician can maximize successful treatment of these patients by recognizing the clinical signs in the early stages of disease, following a logical diagnostic plan to identify the specific etiologic agent involved, and formulating an appropriate and aggressive therapeutic plan. Treatment will not always be successful owing to lack of effective treatments and irreversible neurologic damage.

[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.

Non-neonatal meningitis due to less common bacterial pathogens, the Netherlands, 1975-83

In the Netherlands, case histories of 160 patients aged more than 1 month, with meningitis due to bacteria other than Neisseria meningitidis, Haemophilus influenzae and Streptococcus pneumoniae were reviewed in order to look for associations between the bacteriological data and the course of disease. The incidence of such cases was about 0.8/100,000/year. Escherichia coli and Listeria monocytogenes each accounted for about 15% of the cases. The case-fatality rate was 18.8% (Gram-negative bacteria, 25%; Gram-positives, 15%) and sequelae occurred in 13.3% of the surviving patients (14 and 13% Gram-negative and Gram-positive, respectively). Hearing loss was the most prevalent sequela (5.0%). Predisposing factors were present in 70% of patients (69 and 71% respectively), especially in meningitis due to enteric Gram-negative bacteria (except for salmonella) and due to staphylococci. Surveillance is important because the incidence of meningitis due to these micro-organisms is likely to increase and because the problems in antibiotic treatment have not yet been solved.

Emergence of resistance in gram-negative bacteria: a risk of broad-spectrum beta-lactam use

A number of new beta-lactam antibiotics have been developed to overcome bacterial resistance to older agents. Such resistance usually is caused by plasmid-mediated, constituently produced beta-lactamases. Second- and third-generation cephalosporins, ureidopenicillins, acylamino penicillins, and monobactams generally are resistant to hydrolysis by these enzymes. However, inducible beta-lactamases may confer resistance to these antibiotics. This induction may occur spontaneously or in response to cefoxitin or other beta-lactam agents. The mechanisms by which inducible enzymes produce this resistance are reviewed and implications for the prophylactic and therapeutic use of newer beta-lactams are considered.

Human vitreous levels of cefamandole and moxalactam

We gave 2-g intravenous doses of either cefamandole or moxalactam to 22 patients before vitrectomy. At 1 1/2 to 2 1/2 hours after administration, cefamandole vitreous concentrations varied from 0.36 to 2.05 micrograms/ml (mean, 0.94 micrograms/ml). Individual levels above the minimum inhibitory concentration of cefamandole for 90% (MIC90) of Staphylococcus aureus were found in five of 11 patients. Levels above the MIC90 for S. epidermidis were found in only two of 11 samples. Vitreous concentrations above the MIC90 of cefamandole for common gram-negative pathogens were found in only two patients. Moxalactam concentrations in the vitreous varied from 1.1 to 4 micrograms/ml 30 minutes to six hours after administration. These levels were not above moxalactam's MIC90 for S. aureus or S. epidermidis but were many times higher than the MIC90 of moxalactam for Enterobacteriaceae excluding Pseudomonas.

Cerebrospinal fluid penetration of moxalactam in ventriculostomy patients

The cerebrospinal fluid penetration of moxalactam was simultaneously investigated in three patients with presumed bacterial meningitis. When ratios of simultaneously drawn ventriculostomy to serum moxalactam levels of 1, 2, 3, and 4 h were examined, the penetration ratios were 7.8 +/- 2.4, 11.2 +/- 1.3, 14.2 +/- 2.5, and 15.0 +/- 4.9%, respectively. These ratios were not statistically different from the penetration of moxalactam calculated by the area under the concentration-time curve technique (8.97 +/- 1.89%).

Population analysis of susceptibility to cefotaxime in Enterobacteriaceae

Population analysis of susceptibility to cefotaxime (CTX) in eight species of Enterobacteriaceae was carried out. One strain of each species was examined. The strains represented their individual species as regards natural susceptibility to ampicillin (A) and carbenicillin (Ca). Cephalothinase activity of the parental strains and strains selected on the plates with the highest concentration that allowed growth was determined by an ultraviolet assay. The populations of the A-susceptible/Ca-susceptible (A-s/Ca-s) species, Escherichia coli and Proteus mirabilis were homogeneous as regards susceptibility to CTX. The A-resistant/Ca-resistant (A-r/Ca-r) species, Klebsiella oxytoca and Citrobacter koseri, were less homogeneous, but in all four mentioned species no increase in cephalothinase activity was observed between the parental strains and the strains selected in the population analysis. The four A-r/Ca-s species, Enterobacter cloacae, Citrobacter freundii, Proteus vulgaris, and Morganella morganii, were heterogeneous. The frequency of CTX-r mutants was approx. 10(-6.5). The IC50 for CTX was 2(7.5)-2(8.5) times higher for the mutants than for the parental strains. The CTX resistance was maintained in subcultures of the strains. All four species had a very high increase in cephalothinase activity from parental strains to the strains selected in the population analysis. Only the enzyme of Proteus vulgaris was able to hydrolyze CTX.

Postoperative salmonella meningitis: successful treatment with cefotaxime

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Comparison of ceftriaxone and ampicillin plus chloramphenicol for the therapy of acute bacterial meningitis

Ceftriaxone, a new third-generation cephalosporin, appears to be promising for the therapy of acute bacterial meningitis. The 90% MBCs of ceftriaxone against 54 recent cerebrospinal fluid isolates of Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae were less than or equal to 0.06 to 0.25 micrograms/ml. We examined the efficacy and safety of ceftriaxone therapy of meningitis in Bahia, Brazil. The study was conducted in two phases; in phase A, ceftriaxone was coadministered with ampicillin. The mean cerebrospinal fluid concentrations of ceftriaxone 24 h after an intravenous dose of 80 mg/kg were 4.2 and 2.3 micrograms/ml on days 4 to 6 and 10 to 12 of therapy, respectively. These concentrations were 8- to more than 100-fold greater than the 90% MBCs against the relevant pathogens. In phase B, ceftriaxone (administered once daily at a dose of 80 mg/kg after an initial dose of 100 mg/kg) was compared with conventional dosages of ampicillin and chloramphenicol in a prospective randomized trial of 36 children and adults with meningitis. The groups were comparable based on clinical, laboratory, and etiological parameters. Ceftriaxone given once daily produced results equivalent to those obtained with ampicillin plus chloramphenicol, as judged by cure rate, case fatality ratio, resolution with sequelae, type and severity of sequelae, time to sterility of cerebrospinal fluid, and potentially drug-related adverse effects. The cerebrospinal fluid bactericidal titers obtained 16 to 24 h after ceftriaxone dosing were usually 1:512 to greater than 1:2,048 even late in the treatment course, compared with values of 1:8 to 1:32 in patients receiving ampicillin plus chloramphenicol. Ceftriaxone clearly deserves further evaluation for the therapy of meningitis; the optimal dose, dosing frequency (every 12 h or every 24 h), and duration of therapy remain to be determined.

Current therapy of acute bacterial meningitis in children: Part II

Despite many advances in the past decade in the development of new antimicrobials, acute bacterial meningitis continues to have significant morbidity and mortality in infants and children. Regardless of the effectiveness of the antibiotic preparations, future improvements in outcome is most likely to occur because of more rapid diagnosis and initiation of therapy. The standard penicillins, chloramphenicol, and the aminoglycosides continue to hold an important place in treatment. The recent introduction of new extended spectrum penicillins, including piperacillin and mezlocillin, in addition to the development of the third generation cephalosporins, have expanded alternatives for treating bacterial meningitis. The most appropriate and effective antibiotic or combination of antibiotics must first be selected; thereafter, its use must be monitore to identify its beneficial effects as well as possible adverse effects.

Ceftazidime review

The chemistry, in vitro activity, adverse effects, and clinical indications for the new third-generation cephalosporin, ceftazidime, are reviewed. Ceftazidime appears to have a unique place among the third-generation agents in the treatment of some infectious processes caused by Pseudomonas aeruginosa. It does not demonstrate superiority to other third-generation drugs against Enterobacteriaceae, aerobic gram-positive cocci, or anaerobes. It is eliminated renally and is similar to ceftizoxime, cefoperazone, and moxalactam in half-life. Ceftazidime shares the safety profile of most of the cephalosporins, and has not been shown to have an effect on prothrombin or produce the disulfuram reaction seen with moxalactam and cefoperazone. Specific indications for its use are discussed.

Susceptibility to six antibiotics of group B streptococci isolated from cerebrospinal fluid

64 clinical isolates of group B streptococci from cerebrospinal fluids of neonates were tested for susceptibility to 6 antibiotics. The strains were obtained in The Netherlands during 7 years. The usefulness of the generally recommended initial therapy, a combination of ampicillin and gentamicin, is supported.

Population analysis of susceptibility to cefotaxime and desacetyl-cefotaxime in Staphylococcus and Enterobacteriaceae

Population analyses of susceptibility to cefotaxime (CTX) and desacetyl-cefotaxime (DCTX) of strains of Staphylococcus and some genera of Enterobacteriaceae were carried out. DCTX, which is the main metabolite of CTX, has antimicrobial activity. The penicillinase-producing strains of S. aureus and S. epidermidis were homogeneous as regards susceptibility to both agents. CTX was about 4-8 times more active than DCTX. The methicillin-resistant strains contained a sub-population of resistant bacteria with both CTX and DCTX. The frequency of resistant bacteria was 10(-6) - 10(-5). The E. coli strain was homogeneous to both agents. The strains of Enterobacter cloacae and Citrobacter freundii had a sub-population of resistant bacteria with both agents. The frequency of resistant bacteria was 10(-7) - 10(-4.5). In Klebsiella pneumoniae no resistant sub-population was found. CTX was about four times more active than DCTX with the strains of the Enterobacteriaceae. DCTX had no advantage over CTX as regards homogeneity of susceptibility of the populations examined. CTX seems applicable for treatment of infections with E. coli, Klebsiella pneumoniae, and penicillinase-producing, methicillin-susceptible Staphylococcus, but should not be used alone in treatments of infections with Enterobacter cloacae or Citrobacter freundii.

Clinical pharmacokinetics of the third generation cephalosporins

At the present time, the third generation cephalosporins that are already on the market or close to this point include cefsulodin, cefotaxime, cefoperazone, latamoxef, ceftriaxone, ceftazidime, ceftizoxime and cefotetan. Other newer compounds are also under development but have not been included in this review. None of the third generation compounds is suitable for oral administration and, accordingly, their pharmacokinetics have been studied only after intravenous and intramuscular administration. Microbiological assays and HPLC methods have been used for the measurement of plasma/serum, urine, bile and cerebrospinal fluid (CSF) concentrations. As found with cefotaxime, microbiological assays should only be used when the full metabolite spectrum of a particular drug is known, as otherwise, the presence of microbiologically active metabolites may lead to erroneous conclusions. Under normal conditions, the major route of elimination is via the kidneys for cefsulodin, latamoxef, ceftazidime, ceftizoxime and cefotetan. In contrast, cefoperazone is mainly eliminated in the bile, whereas cefotaxime and ceftriaxone depend both on the liver and the kidneys for their elimination. With the exception of ceftriaxone, which has a longer elimination half-life (i.e. around 8 hours), all the other third generation cephalosporins have a t1/2 ranging between 1.5 and 2.5 hours. Plasma protein binding is variable from one compound to another. However, the clinical relevance of this parameter is not clearly established since tissue penetration also depends on the relative affinity of the drug for tissue components. Third generation cephalosporins seem to penetrate adequately into the CSF and, thus pharmacokinetically appear to be appropriate agents for the treatment of meningitis. The degree of modification of pharmacokinetic parameters by renal insufficiency or hepatic diseases depends, as for other drugs, on the extent to which the compound is excreted via the kidneys or the liver. The third generation cephalosporins have been extensively studied under these conditions and recommendations for dosage modification in special circumstances are available for most of them. The pharmacokinetics of some third generation cephalosporins may be modified in neonates and elderly patients. Accordingly, their use at the extremes of age must be accompanied by a closer than usual clinical monitoring of the patient. From a clinical point of view, the third generation cephalosporins possess reliable pharmacokinetic properties.(ABSTRACT TRUNCATED AT 400 WORDS)

Gram-negative bacillary meningitis

The incidence of gram-negative bacillary meningitis has increased significantly in the past two decades. Approximately two thirds of all reported cases have occurred after neurosurgical procedures. With the development of the newer cephalosporins, the overall mortality rate has decreased from 40 to 80 per cent to 10 to 20 per cent.

Penetration of aztreonam into cerebrospinal fluid of patients with and without inflamed meninges

Aztreonam was administered as a single, 2-g intravenous dose to 25 patients with noninflamed meninges and to 9 patients with inflamed meninges. It was well tolerated and was detected in the cerebrospinal fluid at the initial sampling period at 1 h after the end of infusion. Aztreonam levels in the cerebrospinal fluid of patients with inflamed meninges were four times higher than those recorded for the same time period in patients with noninflamed meninges. Aztreonam concentrations in cerebrospinal fluid in the presence of normal and inflamed meninges exceeded the inhibitory and bactericidal concentrations for most gram-negative bacteria. Thus, a multiple-dose treatment regimen with 2-g intravenous doses every 6 h appears to be appropriate for clinical trials of aztreonam for the treatment of gram-negative bacillary meningitis which is caused by susceptible organisms.

Sequential ventricular fluid concentrations of ceftazidime--report of three cases

Three adult subjects, each with a ventriculostomy, received ceftazidime 2g iv q8h for three doses. Serial samples of serum and CSF ventricular fluid were obtained following the third dose; ceftazidime concentrations were measured by high pressure liquid chromatography. In one patient without inflammatory cells in the CSF, ceftazidime CSF concentrations were only approximately 0.3 micrograms/ml. In two other patients who had inflammatory cells and blood in the CSF, concentrations of ceftazidime in ventricular fluid demonstrated a slow rise and decline over an eight-hour period. Although contamination of the CSF by blood in these two patients confounds the interpretation of the concentrations achieved, it is concluded that obtaining serial samples of CSF from a ventriculostomy offers a more realistic appraisal of the dynamics of antibiotic penetration compared with the single-point method.