Titres of melioidosis haemagglutinating antibodies of 1/40 or more were found in 18 of 905 British, Australian, and New Zealand soldiers serving in West Malaysia. Previous mild unsuspected melioidosis seemed to be responsible for these positive titres, which were more common in men exposed to surface water at work and during recreation. This accords with the current view that soil and surface water is the normal habitat of Pseudomonas pseudomallei, the causal organism. Pyrexia of unknown origin after arriving in Malaysia was significantly more common in men with titres of 1/40 or more than in the remainder. It is suggested that mild melioidosis may present as pyrexia of unknown origin. Pyrexias of unknown origin should be investigated vigorously in patients who are in or who have visited endemic areas.
Three strains of Pseudomonas putrefaciens were isolated from routine clinical specimens at the University Hospital, Kuala Lumpur, Malaysia. Their cultural and biochemical characteristic, and antibiotic susceptibilities are presented. Characteristics of diagnostic value were stressed. Two isolates appeared to have played a pathogenic role in chronic otitis media.
Following the suggestion that it was possible that cases of melioidosis amongst those who had been exposed abroad in the past, might be escaping notice, 487 Royal Marines were examined by indirect haemagglutination studies. Four hundred and eleven of these subjects had served for variable times in areas where melioidosis has been known to occur in Indonesia and Malaya, between 1960 and 1974, occupied in activities in the jungle and paddy fields during which exposure to the disease was to be expected. No evidence of residual subclinical melioidosis was found and it seems unlikely that recrudescent disease will prove to be a problem in the future for English servicemen who have been in South East Asia.
In Malaysia, where vaccination campaigns against foot-and-mouth disease and haemorrhagic septicaemia are routinely carried out, it was desirable to determine whether it was safe and efficacious to administer both vaccines simultaneously. A trial group of 104 cattle was divided into three groups; group 1 animals received both vaccines simultaneously, group 2 animals received only foot-and-mouth disease vaccine and group 3 animals received only haemorrhagic septicaemia vaccine. The serological response to vaccinations was monitored at 0, 21 and 35 days by the virus neutralisation test for foot-and-mouth disease and the mouse-protection and indirect haemagglutination tests for haemorrhagic septicaemia. The simultaneous administration of the two inactivated vaccines produced no adverse effects and the serological response did not differ from the response to either vaccine given separately, thus indicating that cattle may be safely and effectively vaccinated simultaneously in this way.
170 clinical isolates of Pseudomonas aeruginosa were tested for in vitro susceptibility to gentamicin, amikacin, tobramycin, netilmicin, kanamycin, streptomycin, cefotaxime, ceftriaxone, cefoperazone, ceftazidime, moxalactam, azlocillin, piperacillin and ticarcillin. Against 93 gentamicin-sensitive strains, the most active antibiotics were in descending order, ceftazidime, tobramycin, gentamicin, amikacin, and the ureidopenicillins. Against 77 gentamicin-resistant strains, only ceftazidime, amikacin and moxalactam had mode minimum inhibitory concentrations within achievable peak serum levels after standard therapeutic dosage. There was no correlation between cephalosporin resistance and aminoglycoside resistance except for cefoperazone, which, together with the ureidopenicillins and ticarcillin, showed marked decrease in activity against gentamicin-resistant strains.
Trace (microgram liter) quantities of either toluene or benzene injected into an amino-acid-limited continuous culture of Pseudomonas sp. strain T2 were utilized immediately with affinities of 2.6 and 6.8 liters g of cells h, respectively, and yielded large amounts of organic products, carbon dioxide, and cells. The immediate utilization of hydrocarbons by hydrocarbon-deprived organisms helps to establish the nutritional value of nonpolar substrates in the environment. The observation of small Michaelis constants for toluene transport led to tests of metabolic competition between hydrocarbons; however, competitive inhibition of toluene metabolism was not found for benzene, naphthalene, xylene, dodecane, or amino acids. Benzene and terpenes were inhibitory at milligram liter concentrations. Toluene was metabolized by a strongly inducible system when compared with benzene. The capacity of toluene to effect larger affinity values increased with exposure time and concentration. The kinetics of induction suggested saturation phenomena, resulting in an induction constant, K(ind), of 96 mug of toluene liter. Maximal induction of amino-acid-grown cells required about 80 h, with the affinity reaching 317 liters g of cells h.
The current drugs recommended for treatment of melioidosis are tetracycline, chloramphenicol and cotrimoxazole. Unfortunately these drugs are not the drug of choice in an acutely ill patient with septicaemia prior to the availability of laboratory results. With the discovery of the new cephalosporins which have a broad spectrum of activity clinicians are using them either alone or in combination with other antibiotics in such critical situations. Hence, an in-vitro study was carried out on the susceptibility of 41 strains of P. pseudomallei isolated in Malaysia, to these new cephalosporins and a new quinolone. The results showed that all the cephalosporins tested had some activity on the strains tested, with ceftazidime being the most active drug. Pefloxacin had very poor activity. However, further clinical studies are required to determine the duration, dosage and in-vivo activity of the antibiotics.
Fifty seven strains of Pseudomonas pseudomallei were tested for in vitro susceptibility to 15 antimicrobial agents. Amongst the generally recommended antibiotics for therapy of melioidosis, only 86%, 84% and 58% of the strains were found to be sensitive to trimethoprim-sulphamethoxazole, chloramphenicol and tetracycline respectively. Of the newer B-Iactams, in descending order of activity were, ceftazidime, ceftriaxone, cefotaxime, cefoperazone and cefuroxime. But on a weight for weight basis, ceftazidime was the most active agent and as such, may be considered in the therapy of acute septicaemic melioidosis."
The effect of human normal serum (HNS) on Pseudomonas pseudomallei was determined. It is apparent from our data that the organism is resistant to the normal serum bactericidal mechanism. Ancillary experiments to confirm this serum-resistant property of P. pseudomallei were done by examining the effects of growth phase conditions of the bacteria (i.e., logarithmic and stationary phases) and different buffered systems used as diluent in our bactericidal assay. Results obtained showed similar degree of resistance to serum bactericidal killing by 5 strains of the organisms tested. The possible survival advantage of serum-resistance property to P. pseudomallei as bacterial pathogens known to invade the blood stream is discussed.
Antibiotic resistance in Gram-negative bacteria, particularly Salmonella and Shigella, requires surveillance worldwide. This study describes results of surveys in Hong Kong, Bangkok and Kuala Lumpur. All strains were isolated in hospitals which have large community catchment areas in addition to specialised hospital units. The prevalence of resistant strains was high in all areas. Gram-negative bacteria such as Enterobacter associated with hospital infections were resistant to penicillins and cephalosporins, with gentamicin resistance ranging from about 20% in Kuala Lumpur and Hong Kong, to 35% in Bangkok. Ninety-seven percent of Shigella isolated in Thailand were resistant to ampicillin. About 10% of Salmonella were resistant to chloramphenicol in all three centres.
Pseudomonas pseudomallei exotoxin was found to be a potent inhibitor of protein and DNA synthesis in cultured macrophages. Inhibition of DNA synthesis occurred at toxin concentrations as low as 1-2 micrograms/ml and inhibition of 3H-thymidine uptake was almost complete at concentrations of 8 micrograms/ml or more. A close correlation between cell damage and inhibition by DNA synthesis was observed. For protein synthesis, inhibition was obtained at much lower doses (0.06-2.0 micrograms/ml) of the toxin. At similar toxin concentrations, DNA synthesis was marginally affected. Further, it was shown that protein synthesis inhibition occurred almost immediately after incubation, reaching its maximal inhibitory effect of 70% after 6 hr. DNA synthesis, however, was minimally affected by a similar toxin concentration even after 10 hr of incubation. The inhibition of macromolecular synthesis in macrophages by P. pseudomallei exotoxin may be relevant to its modulatory effect on the host defense mechanism.
A 35 year old diabetic presented with features of septicaemia and developed cardiac tamponade. He was found to have pulmonary, acute septicaemic and pericardial melioidosis. Some initial improvement was achieved with medical therapy but only with surgical intervention was a successful outcome achieved.
A nationwide screening program searching for microbial control agents of mosquitos was initiated in Malaysia in 1986. A total of 725 samples were collected and 2,394 bacterial colonies were isolated and screened for larvicidal activity. From such screening, 20 Bacillus thuringiensis, 6 B. sphaericus, 1 Clostridium bifermentans and 2 Pseudomonas pseudomallei larvicidal isolates were obtained. Of these, a new B. thuringiensis named as subspecies malaysianensis was found, while the C. bifermentans was also a new anaerobe individualized as serovar malaysia. It was concluded that this screening program was highly successful.
The in-vitro activity of cefotaxime and cefoperazone were compared using clinically isolated Escherichia coli, Klebsiella spp and Pseudomonas aeruginosa. Cefotaxime was found on a weight to weight basis, to be much more active than cefoperazone. All the three species studied show the presence of cefoperazone-resistant population which were sensitive to cefotaxime. The possible mechanisms of resistance to these antibiotics were discussed.