Antimicrobial resistance of 100 serial gram-negative isolates in two intensive care units.

To determine antimicrobial resistance pattern among gram-negative bacteria isolated from suspected sources of infections in patients hospitalized in two Intensive Care Units (ICUs) at Siriraj Hospital from September 1991 to December 1991, minimal inhibitory concentrations of one-hundred consecutive gram-negative isolates for various antimicrobials were performed using the microbroth dilution method. Of all gram-negative bacterial isolates, 25 per cent were Pseudomonas aeruginosa, 22 per cent Acinetobacter anitratus, 16 per cent Klebsiella pneumoniae, 12 per cent enterobacter, 8 per cent E.coli, 5 per cent non-fermenter, 4 per cent pseudomonas, 3 per cent arizona, 2 per cent A. lwoffii, 1 per cent Aeromonas hydrophila, 1 per cent Aeromonas hydrophila, 1 per cent Proteus rettgeri, and 1 per cent shigella. The in vitro MIC study revealed that 50, 48, 43, 61, 59, 34, 47, 52, 31, 15 per cent of gram-negative isolates were resistant to gentamicin, tobramycin, amikacin, cefotaxime, ceftriaxone, ceftazidime, aztreonam, piperacillin, ciprofloxacin and imipenem respectively. In addition, 64 and 71 per cent of the isolates were resistant to aminoglycosides and cephalosporins being used in the same patients 48 hours before cultures were obtained respectively. The possible spread of resistant gram-negative isolates by cross contamination was not evident by looking at MIC co-variation in sequential isolates of P. aeruginosa. It was concluded that antimicrobial resistance was highly prevalent among gram-negative bacteria isolated from patients already hospitalized in the ICUs. Potent antimicrobials such as imipenem, newer fluoro-quinolones, ceftazidime and amikacin, are often needed for therapy of serious gram-negative bacterial infections in the ICUs.

Re-evaluation of ELISA and latex agglutination test for rheumatoid factor detection in the diagnosis of rheumatoid arthritis.

An indirect ELISA for the determination of each isotype (IgM, IgG, IgA, IgD, IgE) of rheumatoid factors (RF) was performed with sera obtained from 77 patients with either classical or definite rheumatoid arthritis (RA) and 319 controls, using rabbit IgG as the antigen. The results were compared with those of a commercial latex agglutination test, using denatured human gamma globulin as the antigen for rheumatoid factor determination. At the cut-off level at which positive results were found in less than 5% of normal controls, ELISA for IgM RF determination had sensitivity, specificity, efficiency, positive predictive value and negative predictive value of 46.75%, 98.12%, 88.13%, 85.71%, 88.41%, while those for IgA RF were 46.75%, 93.42%, 84.34%, 63.16%, 87.91% and for IgG RF were 59.74%, 92.16%, 85.86%, 64.78%, 90.46%, respectively. These indices by latex agglutination test were 83.11%, 93.73%, 91.67%, 76.19% and 95.83%, respectively. IgD RF titre greater than or equal to 1:5 was detected in 19/77 RA patients and 4/200 normal controls while IgE RF titre greater than or equal to 1:5 was detected only in 7/77 RA patients. Thus, ELISA did not appear to have any advantage over latex agglutination test for diagnosis of RA.

Dot-blot ELISA for the detection of IgM RF and IgA RF.

Dot-blot ELISA was developed for the detection of IgM RF and IgA RF. Normal rabbit IgG (NRIgG), concentration 100 micrograms/ml, was used as the antigen for dotting on the 0.45 microns pore size nitrocellulose membrane. Serum, conjugate and substrate incubation conditions were at room temperature for 1 hour, 1 hour and 3 minutes, respectively. The membrane with NRIgG dot could be sotred for 6 weeks before use in the assay. Positive results of IgM RF, at the serum dilution 1:800, were found in 31/51 patients with either classical or definite rheumatoid arthritis and 3/68 normal healthy individuals. Positive IgA RF, at the serum dilution 1:100, was found in 27/51 of the former and none of the latter. Significant concordance with high agreement index was found between the results of the dot-blot ELISA developed and those obtained from ELISA performed in microtitre plate (Kappa greater than or equal to 0.78 for IgM RF and 0.83 for IgA RF, p less than 0.001).

HIV infection in male patients attending a sexually transmitted disease clinic.

Three hundred and fifty-two heterosexual males, attending a sexually transmitted disease clinic at Siriraj Hospital from December 1989 to February 1991 were studied for the prevalence of HIV infection. Of these, 334 men reported prostitutes as the main source of their sexually transmitted disease. No one had received blood transfusion in the last 5 years, and there was no history of intravenous drug use, homosexuality or bisexuality. HIV antibody was found in the sera of 24 men (6.8%). HIV seropositivity was associated with serologic makers of syphilis (P < 0.05) but was not associated with present genital ulcers on physical examination or other STDs. These data indicate the high rate of female prostitutes to male transmission of HIV infection in the presence of sexually transmitted disease and confirms the relationship between syphilis and HIV infection. HIV/AIDS educational programmes and campaigns to promote condom use among prostitutes and clients are an urgent need in Thailand.