Clostridium difficile infections in HIV-positive patients.

The prevalence of Clostridium difficile infections in HIV-positive patients with regard to the presence of its enterotoxin was investigated. Enzyme immunoassay (EIA, Meridian Diagnostic Inc) was used for the detection of C. difficile enterotoxin in stool specimens collected from 201 HIV-positive and 271 HIV-negative diarrheal patients. Culture was performed on cycloserine cefoxitin fructose agar. Chromosomal DNA types of C. difficile isolates were determined by pulsed-field gel electrophoresis (PFGE). In the HIV-positive group, C. difficile enterotoxin was found in 58.8% and 12.6% of diarrheal and non-diarrheal patients, repectively, whereas this toxin was found in 36.5% of HIV-negative-diarrheal patients. However, 13.6% of stool samples were negative by toxin assay, but were positive for C. difficile by culture and latex agglutination test. Among 11 isolates from both HIV-positive and HIV-negative patients, 6 patterns of PFGE type were observed: A, B, C, D, E and F.

Serotyping of Cryptococcus neoformans strains isolated from clinical specimens in Thailand and their susceptibility to various antifungal agents.

One hundred and thirty-nine strains of Cryptococcus neoformans were isolated in Thailand from clinical specimens including 97 AIDS patients: 67 from Northern, 48 from Central, 17 from Northeastern and 7 from Southern regional hospitals. Six out of the 139 strains were serotype B and the remaining 133 were A. There was no correlation between serotypes and regional distribution. To our knowledge, this is the first report of serotyping studies on C. neoformans in Thailand. Studies on random amplified polymorphic DNA (RAPD) analysis showed that this method is useful for the differentiation of C. neoformans var. gattii (serotypes B and C) and C. neoformans var. neoformans (serotypes A and D). They also indicated that Thai isolates of C. neoformans var. gattii (serotype B) were a homogeneous group on the basis of their genotypes. Antifungal susceptibility tests using 5 antifungal agents including amphotericin B, fluconazole, flucytosine, itraconazole and micronazole against 50 selected strains of C. neoformans showed that they were sensitive to all of the antifungal agents tested except for one strain that was resistant to flucytosine.

Isolation rates of Burkholderia pseudomallei among the four regions in Thailand.

This study aimed to compare the isolation rates of Burkholderia pseudomallei among community-based hospitals located in the central, north, northeast, and south of Thailand. A questionnaire inquiring about the number of isolation of B. pseudomallei from various clinical specimens during 1994-95 were mailed to 141 community-based hospitals. Of these, 125 hospitals (88.6%) responded to the questionnaire. Microbiological laboratory was not available in thirty hospitals. Data from 95 remaining hospitals with capability to do bacterial culture showed that B. pseudomallei was never isolated in 49 hospitals. Eleven, 9, 19 and 7 hospitals where B. pseudomallei has been isolated, are located in the central, north, northeast and south of Thailand respectively. From these 46 hospitals, a total of 1,131 strains of B. pseudomallei were isolated from 407,263 specimens in 1994 and 1,165 strains from 440,541 specimens in 1995. However, the isolation was most frequent in northeastern hospitals, which accounted for 890 and 964 strains in 1994 and 1995 respectively while only 94, 76, 71 and 83, 75, 43 strains were simultaneously isolated during the 2-year period in those located in central, north and south respectively. The isolation rates of B. speudomallei in 1994 and 1995 were 4.2 and 4.1 per 1,000 clinical specimens in northeastern hospitals as compared to 1.1, 1.8, 1.1 and 1.1, 1.2, 0.7 in those located in central, north and south respectively. Ubon Ratchathani, Nakhon Ratchasima, Buri Ram, Khon Kaen and Udon Thani were the five provinces which exhibited the highest isolation rates as follows; 244, 150, 147, 127, 100 and 218, 128, 114, 119, 58, in 1994 and 1995, respectively. It was concluded that B.pseudomallei was most commonly isolated in the northeast of Thailand. Under-recognition of B. pseudomallei may prevail not only in other parts of Thailand but in some areas of the northeast as well.

In vitro antifungal activity of the new triazole D0870 against Penicillium marneffei compared with that of amphotericin B, fluconazole, itraconazole, miconazole and flucytosine.

The in vitro activity of D0870, a new triazole, was compared with that of fluconazole, itraconazole, miconazole, amphotericin B and flucytosine against recent clinical isolates of Penicillium marneffei in Thailand. The minimum inhibitory concentrations (MIC) values were determined by a microbroth dilution method using morpholinopropanesulphonic acid (MOPS)-buffered RPMI-1640 and brain heart infusion (BHI) medium. Yeast nitrogen base (YNB) medium with glucose was also used for the assay of flucytosine. D0870 was less active against P. marneffei than itraconazole, but its activity was similar to that of miconazole, superior to that of amphotericin B and markedly superior to that of fluconazole and flucytosine. Much lower MIC values of D0870 were observed with BHI medium.

Antibacterial activity of teicoplanin against Clostridium difficile.

The in vitro inhibitory action of teicoplanin, vancomycin, metronidazole and clindamycin against clinical isolates of Clostridium difficile was investigated. Minimum inhibitory concentrations (MICs) were determined using E test. Teicoplanin (MIC range 0.023-0.75 microgram/ml), vancomycin (MIC range 0.5-3 micrograms/ml) and metronidazole (MIC range 0.19-1 microgram/ml) were all very active against the isolates examined. No resistant strains of C. difficile to those three antimicrobial agents were observed, whereas resistance to clindamycin was found in 39.5% of the tested strains. Teicoplanin was about 4-times more potent than vancomycin. It appears to be a more promising antimicrobial for treatment of C. difficile enteric disease.

Pathogenic Nocardia isolated from clinical specimens including those of AIDS patients in Thailand.

Forty strains of nocardioform microorganisms were isolated as clinical specimens including several from AIDS patients in Thailand. Among them, 37 strains were found to belong to the genus Nocardia. Our identification studies revealed that most of the strains (25 strains) belong to the N. asteroides group, i.e., N. asteroides sensu stricto and N. farcinica. Three strains were identified as N. otitidiscaviarum and two strains N. brasiliensis. In addition, 7 strains of rare pathogenic N. transvalensis were also isolated.

PIP: Nocardia is an aerobic gram-positive and partly acid-fast bacterium that belongs to the pathogenic actinomycetes. Nocardia can cause both systemic and cutaneous diseases. Cutaneous nocardiosis is thought to be induced by various predisposing factors, the most common of which include corticosteroid therapy, immunosuppressive therapy, and hematological malignancy. In recent years cases of infection have been increasing coupled with the increased use of immunosuppressive agents and the number of AIDS patients. Characterization studies of pathogenic Nocardia isolated clinically in Thailand from 1990 to 1994 were reported. 40 strains of nocardioform microorganisms (Nocardia like actinomycetes with meso-DAP, arabinose, galactose, and mycolic acid) were isolated as clinical specimens including several from AIDS patients. All 40 strains were isolated from clinical specimens at seven hospitals in Bangkok using Sabouraud dextrose agar medium or Ogawa medium. The analysis of mycolic acid profiles on thin-layer chromatography (TLC) plate showed that one strain had the same Rf values as that of Mycobacterium sp. and the remaining 39 strains had similar Rf values to those of Nocardia, Rhodococcus, and Gordona spp. Studies on their menaquinone composition showed that among 39 isolates, 37 strains had MK-8H4 (cycl.) as predominant menaquinone. 2 strains had MK-8(H2) as a predominant menaquinone and both were identified as Rhodococcus spp. 25 strains were found to belong to the N. asteroides group and were further divided into respective species, i.e., 12 strains of N. asteroides in a strict sense and 13 strains of N. farcinica on the basis of Na-citrate utilization, susceptibility to antimicrobial and antitumor agent (tobramycin and 5-fluorouracil), and ability to grow at 45 degrees Celsius. Three strains of N. otitidiscaviarum and two strains of N. brasiliensis were also identified and the remaining seven strains were eventually identified as N. transvalensis. Results of the drug susceptibility pattern test of Nocardia isolates correlated well with those obtained by the traditional identification system. Among 37 cases, there were 10 HIV seropositive and 2 seronegative patients, and the remaining cases were unknown. Further epidemiological studies may be needed to determine a possible association between AIDS and nocardiosis.

Environmental surveillance of Legionella species in Thailand.

Legionellae was found in 57 per cent of 94 cooling towers and 21.8 per cent of 78 other environmental sources. These figures reveal that the existence of legionellae in cooling towers is more prevalent than that found in other environmental sources. Legionella pneumophila serogroup 1 was the most prevalent organism among the legionellae found in cooling towers and other environmental sources. The recovery of legionellae in each province was seasonally independent and was found throughout the year. This is the first report of an environmental survey representing the existence of legionellae in every region of Thailand.

A monoclonal antibody-based dot-blot ELISA diagnostic kit for the detection of Vibrio cholerae 01 in stools of diarrheic patients and household contacts.

A "cholera diagnostic kit" was developed for sensitive, specific, rapid, and inexpensive detection of Vibrio cholerae 01. The monoclonal antibody specific to antigen A of Vibrio cholerae 01 was used as an antigen detection reagent and the principle of dot-blot ELISA was adopted. The kits were used in seven Regional Medical Sciences Centres, Ministry of Public Health, located at various regions of Thailand where diarrhea occurs frequently. Diagnostic efficiency of the kits in the detection of Vibrio cholerae 01 from rectal swabs of the diarrheic patients and their household contacts was evaluated in comparison with the conventional culture method. The two methods were found to have excellent degree of agreement (kappa values > 95%). The dot-blot ELISA has several advantages over the culture methods, ie rapid (dot-blot ELISA takes 1-2 hours while the culture method takes at least two days) and inexpensive. It requires no sophisticated equipment. The procedure is not complicated thus it is easy to train personnel. The diagnostic kits are recommended for use in the detection of severe diarrhea caused by V. cholerae 01 not only in hospitals and health centres where adequate treatment of the patients is required as a life-saving measure but also for early recognition of cholera cases and their contacts so that other action, ie prevention and control of outbreaks and surveillance can be promptly implemented.

Reactivity of the CD D-1 latex test with Clostridium difficile and other bacteria.

The reactivity of a commercial latex test with thirty-three species of bacteria was tested. Toxigenic and nontoxigenic strains of Clostridium difficile gave a positive result in the CD D-1 latex test. Cross-reactions were also given by C. putrificum, C. sporogenes and proteolytic C. botulinum.