Experimental Klebsiella septicemia in mice: treatment with specific antibodies from the rabbit alone and in combination with gentamicin

Monoclonal antibodies--immunotherapy for the critically ill

Monoclonal antibodies (mAb) have revolutionised many areas of medicine, particularly research and diagnostics. Murine, human and humanized mAb have all been developed. The most important clinical applications to date have been in the fields of transplantation and oncology. Experimental and limited clinical trials suggest mAb are emerging as a new therapeutic strategy in the critically ill. Antibodies against a variety of bacteria or their products are potentially useful in gram-positive and gram-negative shock. Anti-cytokine and anti-neutrophil adhesion molecule mAb may be effective not only in septic shock but also in other conditions associated with acute inflammation and cytokine release, e.g., acid aspiration, ischaemia/reperfusion injury (myocardial infarction, haemorrhagic shock, aortic aneurysm repair). Antibodies inhibiting neutrophil adhesion may also be efficacious in asthma, pulmonary fibrosis, meningitis and cerebral malaria. The use of these and other mAb in intensive care is an exciting prospect and future clinical studies will determine the extent of their role in the management of the critically ill.

Monoclonal antibody against Klebsiella capsular polysaccharide reduces severity and hematogenic spread of experimental Klebsiella pneumoniae pneumonia

Klebsiella pneumoniae is an important nosocomial pathogen causing severe pulmonary infections. The majority of clinical Klebsiella isolates produce a high-molecular-weight capsular polysaccharide (CPS) which is one of the dominant virulence factors. In the present study, we examined the potency of a murine immunoglobulin M monoclonal antibody (MAb) with specificity to Klebsiella type 2 CPS to protect rats against experimental Klebsiella pneumonia. The MAb did not prevent the invasion of virulent bacteria into the interalveolar space. However, the resolution of infection was accelerated in MAb-treated animals. This was demonstrated by (i) less severe weight loss and (ii) markedly reduced inflammatory reactions in the lung. The elimination of bacteria was significantly increased not only in the lungs but also in the livers of antibody-treated rats. This was reflected by reduced levels of circulating, soluble CPS and MAb-bound CPS. A mixture of human MAbs with specificity to CPS of clinically important Klebsiella serotypes may prove to be a useful tool for the prevention or supportive treatment of Klebsiella pneumonia.

Comparative efficacy of ciprofloxacin, azlocillin, imipenem/cilastatin and tobramycin in a model of experimental septicemia due to Pseudomonas aeruginosa in neutropenic mice

The in vivo activity of ciprofloxacin against Pseudomonas aeruginosa was studied in a septicemia model in neutropenic mice and compared to that of other antibiotics with established activity against P. aeruginosa. When given as a single agent, ciprofloxacin proved to be as effective as imipenem/cilastatin, whereas azlocillin and tobramycin were rather ineffective. After infection with higher challenge inocula, combinations of two (synergistic) antibiotics were more effective than single agent therapy in most instances. The combination of ciprofloxacin with azlocillin was at least as effective as that of imipenem/cilastatin with tobramycin. Selection of mutants with decreased sensitivity to ciprofloxacin occurred during therapy, however, post-therapy MICs of ciprofloxacin did not exceed a level of 1 mg/l and rises of MICs did not detrimentally influence treatment outcome. Taken together with the results of earlier studies, our data encourage the use of ciprofloxacin in gram-negative septicemia in neutropenic patients.

A murine monoclonal antibody against Klebsiella capsular polysaccharide is opsonic in vitro and protects against experimental Klebsiella pneumoniae infection

Murine monoclonal antibodies (mAb) of the immunoglobulin M class specific for the K2 capsular polysaccharide (CPS) of Klebsiella were isolated. One such mAb, termed III/5-1, was selected for further study. This mAb promoted the uptake and killing of Klebsiella pneumoniae K2 strains by human granulocytes and activated complement after contact with the bacteria. The efficiency of mAb-mediated phagocytosis and complement activation was inversely related to the amount of capsular material produced by the test strain. MAb III/5-1 was found to be effective at preventing fatal experimental K. pneumoniae K2 sepsis when administered prophylactically, the degree of protection being dependent upon the amount of CPS produced by the challenge strain.

Comparative efficacy of ciprofloxacin, ceftazidime and gentamicin, given alone or in combination, in a model of experimental septicemia due to Klebsiella pneumoniae in neutropenic mice

The therapeutic efficacy of ciprofloxacin, used alone and in combination with either ceftazidime or gentamicin, was evaluated in a model of experimental Klebsiella pneumoniae septicemia in neutropenic mice. Therapeutic results were compared to those achieved by treatment with ceftazidime or gentamicin alone, as well as their combination. Infections were induced by i.v. injection of two strains of K. pneumoniae. Therapy with i.m. antibiotics was performed in 8 h intervals for a total of 13 doses, and survival rates were recorded at the end of treatment as well as seven days later. Ciprofloxacin alone proved to be significantly more effective than ceftazidime and gentamicin, producing survival rates similar to the combination of ceftazidime plus gentamicin. Bacterial counts of spleens and blood confirmed the superior bactericidal activity of ciprofloxacin. Except for the combination of ciprofloxacin with ceftazidime, there was no apparent advantage of combinations of ciprofloxacin with the other agents compared to ciprofloxacin alone. These data suggest a high in vivo activity of ciprofloxacin in systemic infection due to K. pneumoniae.