A mycobacterial lipoarabinomannan specific monoclonal antibody and its F(ab') fragment prolong survival of mice infected with Mycobacterium tuberculosis

Lipoarabinomannan (LAM) is a major structural carbohydrate antigen of the outer surface of Mycobacterium tuberculosis. High antibody titres against LAM are often seen in active tuberculosis (TB). The role of such LAM-specific antibodies in the immune response against TB is unknown. Here we have investigated a monoclonal antibody (MoAb) SMITB14 of IgG1 subclass and its corresponding F(ab')(2) fragment directed against LAM from M. tuberculosis strain H37Rv. MoAb SMITB14 was shown by immunofluorescence to bind to whole cells of the clinical isolate M. tuberculosis strain Harlingen as well as to M. tuberculosis H37Rv. The binding of MoAb SMITB14 to LAM was inhibited by arabinomannan (AM) and oligosaccharides (5.2 kDa) derived from LAM, showing that the MoAb binds specifically to the AM carbohydrate portion of LAM. In passive protection experiments BALB/c mice were infected intravenously with M. tuberculosis Harlingen. MoAb SMITB14 was added intravenously either prior to, or together with, the bacteria. The antibody proved to be protective against the M. tuberculosis infection in terms of a dose-dependent reduction in bacterial load in spleens and lungs, reduced weight loss and, most importantly, increased long-term survival.

RNA amplification for direct detection of mycobacterium tuberculosis in respiratory samples

A target amplified test system (AMTDT, Gen-Probe, San Diego, California, USA) was compared with conventional standard methods in the detection of Mycobacterium tuberculosis in sputum and other respiratory specimens from patients with suspected tuberculosis. The highest incidence of positive samples was seen with the AMTDT test. Out of 450 samples from patients with known or suspected tuberculosis, 43 (9.6%) were positive by culture, and 47 (10.4%) with AMTDT. After discrepancy analysis, 7 of the culture-negative but AMTDT-positive samples were judged to be true positive, giving the AMTDT a sensitivity of 92.0% and a specificity of 99.8%. The AMTDT test was rapid, easy to perform, sensitive, and highly specific.

Mycobacterium avium complex develop resistance to synergistically active drug combinations during infection

Isolates of Mycobacterium avium complex from five patients on longterm (3-5 yrs) anti-mycobacterial drug treatment were collected during the early and late phase of disease, and studied in vitro for their susceptibility to anti-mycobacterial drugs and drug-combinations. All isolates were resistant or moderately resistant to ethambutol, rifampicin and streptomycin when given singly; however, all strains isolated early in the disease were susceptible to the combination of ethambutol with either rifampicin or streptomycin. All late isolates had developed resistance to one or both of these combinations. Three of the patients died within a year after the last isolation of M. avium complex, and the two remaining patients still have severe chronic disease. It is concluded that the susceptibility of M. avium strains to combinations of drugs should be monitored during the course of treatment, in order to guide the selection of effective drug-combinations throughout the infection.

Pathogenic significance of P-fimbriated Escherichia coli in urinary tract infections

The over-all aim of this study was to determine the pathogenic significance, and bacteriological and serological characteristics of P-fimbriated organisms isolated from a general population of patients with bacteriuria. A P-receptor specific particle agglutination test was used to identify P-fimbriated bacteria among 2,010 isolates from male and female patients with bacteriuria (age range infancy to 91 years). Of the 2,010 isolates 206 (10.2 per cent) were positive for P-fimbriae by the P-receptor specific particle agglutination test. Only Escherichia coli was found to be P-fimbriated, with an incidence of 21.5 per cent among 956 Escherichia coli isolates. The critical characteristic of pyelonephritic strains of Escherichia coli was P-fimbriation. In cases of nonobstructive acute pyelonephritis 100 per cent of the infecting bacteria were P-fimbriated. The data indicated clearly that the serotype, biotype, presence of type 1 fimbriae (mannose sensitive), undefined mannose-resistant adhesions, hemolysin production and motility of P-fimbriated Escherichia coli were clinically unimportant differential strain characteristics and not indicative of the virulence of P-fimbriated Escherichia coli within clinical syndromes. Isogenic P-fimbriated Escherichia coli strains were isolated from noncompromised patients in all clinical categories, that is pyelonephritis, asymptomatic bacteriuria and cystitis. A variety of bacterial strains appears to be capable of causing acute pyelonephritis in the presence of obstructive uropathic conditions, regardless of P-fimbriation. Therefore, P-fimbriation becomes a noncritical factor in compromised patients. The P-receptor specific particle agglutination test is a simple and rapid method to determine whether bacteria are P-fimbriated and may be an important screening method to identify those bacteria isolated from individuals at risk for nonobstructive acute pyelonephritis.

Experimental pyelonephritis in the monkey. VII. Ascending pyelonephritis in the absence of vesicoureteral reflux

Six adult male nonrefluxing monkeys were experimentally infected by inoculation of P-fimbriated E. coli into the bladder. Eight control monkeys were inoculated with a non-P-fimbriated E. coli strain. Inoculation with the P-fimbriated E. coli resulted in marked leukocytosis, prolonged bacteriuria and loss of renal function with a 66 per cent incidence of pyelonephritis. Death secondary to bilateral pyelonephritis was seen in 2 monkeys inoculated with P-fimbriated E. coli. Pyelonephritis was not seen in any of the monkeys inoculated with non-P-fimbriated E. coli. The study shows that ascending pyelonephritis can occur in monkeys in the absence of vesicoureteral reflux.