Surveillance of antibiotic resistance in South East Asia.

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.

Evaluation of central venous catheter sepsis by differential quantitative blood culture.

The accuracy of differential quantitative blood culture in the diagnosis of central venous catheter sepsis was evaluated in 24 parenterally-fed patients in whom catheter sepsis was suspected. The pour-plate quantitative culture technique was performed immediately before removal of the catheter on blood drawn through the central venous catheter and a peripheral vein. If bacterial colonies in the catheter blood specimen were sevenfold more frequent than identical bacterial colonies in the peripheral blood specimen, the test was considered positive and indicative of catheter sepsis. Catheter-tip culture identified 9 of the 24 patients as positive for catheter sepsis. A positive differential quantitative blood culture result was found for seven of the nine infected catheters. Sensitivity of this test was 77.8%, specificity was 100%, and overall accuracy was 91.7%. It is concluded that differential quantitative blood culture is a reliable method for the exclusion of catheter sepsis.

Predictive value of surveillance skin and hub cultures in central venous catheters sepsis.

In a prospective study of septic complications of central venous catheters used for total parenteral nutrition, daily surveillance catheter hub cultures and twice weekly skin cultures at the catheter entry site were evaluated for their predictive value for catheter sepsis, i.e. bacteraemia with an identical species as that recovered from the catheter tip, or catheters which grew greater than or equal to 15 cfus by a semiquantitative method and/or greater than or equal to 10(3) cfus by a quantitative method. Of 142 catheters studied, 29 were identified to have catheter sepsis. For these the sensitivity of the surveillance hub culture was 34.5% and the sensitivity of the skin culture was 37.9%. When either the hub or the skin culture result was considered as an indication of catheter sepsis, the sensitivity increased to 79.3%. The positive and negative predictive value of the combined result was 44.2% and 93.3% respectively. This study suggests that simultaneous hub and skin cultures are required for a satisfactory surveillance.

Once daily administration of netilmicin compared with thrice daily, both in combination with metronidazole, in gangrenous and perforated appendicitis.

The safety and efficacy of a single daily dose of netilmicin plus metronidazole after appendicectomy for gangrenous and perforated appendicitis was compared with the traditional thrice daily dosage. Twenty patients were enrolled in each group. The antibiotics were given intramuscularly for seven days after operation. Eradication of infection was observed in all patients and the postoperative wound sepsis was the same for each group. A significantly higher peak serum netilmicin level was achieved in the group receiving a single daily dose but nephrotoxicity was not observed. We concluded that the single daily dose of netilmicin was well tolerated and was as efficacious in this small series as the thrice daily regimen. The single-dose regimen has the advantage of simplicity and potentially increased bactericidal activity.

In vitro and in vivo study of fosfomycin in methicillin-resistant Staphylococcus aureus septicaemia.

Five hundred strains of methicillin-resistant Staphylococcus aureus were tested against various anti-staphylococcal agents. Vancomycin, fusidic acid and fosfomycin were found to be the most effective. Only 1 strain out of 500 was resistant to fosfomycin. Three patients with methicillin-resistant Staphylococcus aureus septicaemia were successfully treated by fosfomycin. We conclude that fosfomycin could be the drug of choice for methicillin-resistant Staphylococcus aureus infection.

Laboratory evaluation of enoxacin: comparison with norfloxacin and nalidixic acid.

Enoxacin displayed activity similar to that of norfloxacin against enterobacteria, Pseudomonas aeruginosa, staphylococci, streptococci and Bacteroides spp. The activity of enoxacin against many strains was reduced in acid conditions, but the pH effect was not so marked as that seen with norfloxacin. Nalidixic acid was found to be more active in acid conditions, particularly against staphylococci, Streptococcus faecalis and Ps. aeruginosa. In conditions simulating the treatment of bacterial cystitis, a single dose of enoxacin, achieving a peak concentration of 50 mg/l, suppressed growth of nalidixic acid-sensitive and -resistant Gram-negative bacilli for periods of between 18 and 25 X 5 h. Reduced susceptibility of bacteria surviving exposure to enoxacin was observed in one nalidixic acid-resistant strain of Escherichia coli and in nalidixic acid-sensitive strains exposed to low doses (peak concentration = 5 mg/l) of enoxacin. These results are similar to those obtained with norfloxacin and substantially better than those obtained with nalidixic acid.

The bacteriology and septic complication of patients with appendicitis.

A detailed bacteriologic study was done on 161 patients operated for appendicitis. Aerobic and anaerobic cultures were taken from the blood, the appendicular lumen, mucosa, serosa, fossa, and from the wound after closure of the peritoneum. There is no correlation between the degree of appendicitis and the incidence of positive blood culture. The infection spread through the appendicular wall as the disease progressed. Aerobic infection was common in early appendicitis but a mixed aerobic and anaerobic infection was predominant in late cases. Late appendicitis, a positive wound culture at the end of the operation, the duration of symptoms of over 36 hours before operation and the age of the patient over 50 years were all associated with an increased incidence of septic complication. From the antibiotic sensitivity on the bacteria isolated, the most effective agent against anaerobes was metronidazole. Effective agents against the aerobes were aminoglycosides and cephalosporins. The best single agent against both anaerobes and aerobes was moxalactum.

Accessory replicons of species of Salmonella and Shigella.

Shigella and Salmonella strains isolated from clinical samples were examined. Out of 42 Shigella strains tested, 17 (40%) were found to be colicinogenic and another 3 were lysogenic. All three lysogens yielded a phage antigenically homologous to coliphage P2. Out of 30 strains tested, only 1 was found to be resistant to both neomycin and sulfamethoxazole. Out of 48 strains of Salmonella tested for drug resistance, only 2 showed multiple drug resistance. In contrast to Shigella isolates, the Salmonella isolates were infrequently (approximately 5%) bacteriocinogenic. The frequency of lysogeny in Salmonella strains was found to be 6% when tested on Salmonella typhimurium LT2, but by using a set of five indicators belonging to species Salmonella potsdam, Salmonella mbadanka, Salmonella dublin, Salmonella london, and Salmonella wandsworth, 50% of the strains were shown to be lysogenic. Salmonella phages related to P22 were recoverable from Salmonella saintpaul, Salmonella indiana, and Salmonella heidelberg. Some isolates of S. typhimurium yielded a temperature-sensitive and P22-heterologous phage which was found to be a more efficient transducer of bacterial genetic markers than P22. EcoRI-generated fragments of the DNA of some phages permitted the establishment of a clonal descent for some of the wild-type lysogenic bacterial strains. This last observation points out the potential usefulness of prophages as epidemiological markers.

The bacteriology of recurrent pyogenic cholangitis and associated diseases.

Ninety-five patients with recurrent pyogenic cholangitis had a range of specimens taken at laparotomy for bacterial culture. Bacteria were isolated from 68% of cases. Escherichia coli was the predominant pathogen. Other aerobic and anaerobic intestinal bacteria were also isolated. Liver biopsy, bile and gallstones were the most rewarding specimens for culture. Infection was usually localized, but systemic infection occurred occasionally. The site of infection is probably in the liver parenchyma; however, the route by which intestinal bacteria invade the liver is not known. Sixty per cent of the cases of recurrent pyogenic cholangitis had gallstones and 20% were infected with Clonorchis sinensis.

Tuberculoid cutaneous infection due to a niacin-positive Mycobacterium chelonei.

A case of cutaneous infection due to a niacin-positive Mycobacterium chelonei (previously called M. abscessus) on the dorsum of the hand of a professional cotton-classifier is reported from Hong Kong. The infection was probably directly acquired from handling contaminated raw cotton. The patient was successfully treated with combined anti-tuberculous drugs over a period of 1 year. Histologically, the skin lesion showed tuberculoid granulomas, in addition to abscesses.

Salmonella gastroenteritis in Hong Kong--a clinical review of 200 patients.

A sudden increase in Salmonella gastroenteritis affecting infants and children in Hong Kong in 1971 prompted a clinical review of 200 such patients seen over a 6 year period. It showed unprecedented prevalence of Salmonella johannesburg infections and unusually protracted diarrhoea. Only 3.5 per cent of patients were breast fed. Factors causing this chronicity are discussed. All 8 fatal cases were under 7 1/2 months old, with protracted diarrhoea starting within 1 month after birth in 7. The invasiveness of Salmonella johannesburg is low although its infectivity high. Bacteraemia occurred in only 1 patient and focal infections other than gastroenteritis in none. Antibiotics did not improve diarrhoea nor eliminate faecal excretion in the majority of those treated. Prolonged and intermittent faecal excretion of Salmonella was common. Nineteen per cent of patients acquired diarrhoea in hospital; some after a course of antibiotics given for other infections. Experience from this series does not recommend administration of antibiotics to patients with uncomplicated Salmonella johannesburg gastroenteritis. As chronicity of diarrhoea seemed to be the major prognostic factor with regard to mortality and morbidity in this series, further search for causes and control measures of this chronicity is required.

Escherichia coli serotypes throughout the gastrointestinal tract of patients with intestinal disorders.

The O and H serotypes of Escherichia coli that were present along the entire length of the gastrointestinal tract of patients with small intestinal bacterial overgrowth were studied. Multiple sero- and biotypes were represented, although usually a single serotype predominated in each patient. In a number of cases the different O:H serotypes were antigenically related indicating that antigenic degradation was occurring. The serotypes isolated from the stomach and small intestine were represented in the faeces. In general, within the limitations of this study, there appears to be a stable ecosystem in each patient and it may require specific oral antibiotics to alter it.

Hospital Salmonella johannesburg infection and its possible role in the community spread of the infection in Hong Kong.

Salmonella johannesburg (1, 40: b: e, n, x), a previously rare salmonella serotype, has established itself rapidly as an important and highly prevalent cause of gastroenteritis among children. The clinical features of the infection are usually mild but chronic. It has been suggested that S. johannesburg was introduced into Hong Kong through imported foods but no common vehicle could be traced as the source of infection. A thorough investigation of one paediatric ward in a general hospital revealed that non-infected patients admitted to the ward usually acquired S. johannesburg infection within 3-7 days, with or without symptoms. Thus hospital cross-infection could be a significant factor in contributing to its rapid spread in the community. Furthermore, the rapidity with which S. johannesburg spread was facilitated by (a) its tendency to produce a chronic infection, (b) its multiple resistance to antibiotics, and (c) the higher infectivity of S. johannesburg over other salmonellas endemic in this locality. These factors combined with the overcrowded conditions in many of the hospitals in Hong Kong facilitated the occurrence of hospital infection, which in its turn contributed to the spread of the infection in the local community.

Neonatal infection due to Salmonella worthington transmitted by a delivery-room suction apparatus.

An outbreak of diarrhoea due to Salmonella worthington in five newborn babies, 5 weeks after a similar outbreak in 13 babies for which no cause had been found, occurred in the nursery of a maternity ward. The source of infection was traced to the contaminated rubber tubing of a mechanical suction apparatus. S. worthington was isolated from the rubber tubing and the Y connexion of the suction apparatus from which all the five infected babies had received suction. Reflux of contaminated amniotic fluid into the sterile catheter connected to the apparatus some time before use could have been the means of introducing the infected material to the oropharynx of the newborn babies, and amniotic fluid, acting as a good medium to support the growth of S. worthington, might be responsible for the long-lasting contamination.

Indirect immunofluorescence assay for antibody to germ tube of Candida albicans--a new diagnostic test.

Indirect immunofluorescent and agglutination assay were used to study the anti-Candida albicans reactivities in the serum of 13 normal subjects and 14 patients infected with C. albicans. A significant increase in anti-C. albicans seroreactivity was observed during infection with this organism but the increase in the anti-germ tube immunofluorescence titre was the more marked. It is evident that the anti-germ tube immunofluorescence assay is more discriminatory for C. albicans infection than the conventional agglutination assay.

Faecal steroids and bacteria and large bowel cancer in Hong Kong by socio-economic groups.

In a study of three socio-economic groups in Hong Kong, the high income group had a high faecal concentration of bile acids, especially the dihydroxy bile acids, compared to the low income group. The faecal bile acids were also more highly degraded. The faecal flora contained more bacteroides and fewer eubacteria. Very few of the clostridia able to dehydrogenate the steroid nucleus were isolated. An epidemiological study based on street blocks indicated that the high income group also have a higher incidence of cancer of the large bowel and of the breast. The results are discussed in terms of theories on the aetiology of large bowel cancer.

Spread of Escherichia coli colonizing newborn babies and their mothers.

Most babies are colonized by the predominant strains of Escherichia coli present in their own mother's faecal flora. Those babies who did not acquire their maternal faecal flora acquired strains of E. coli belonging to a small number of the possible serotypes. Moreover, the same serotypes were found in several babies and other mothers, suggesting spread within the ward. These few strains included some of the O groups which had previously commonly been found as urinary pathogens. These strains may have increased potentialities for colonization of human bowel. Antigenic and biochemical variation was observed among the strains.

Further studies of Escherichia coli in babies after normal delivery.

Previous work showed that on the basis of O serotyping alone of Escherichia coli, the majority of babies acquired the same O serotype as was found in the stools of their respective mothers. Further characterization of the E. coli by H serotyping, determination of their antibiotic resistance and ability to ferment six carbohydrates showed that in the majority of cases the previous results were confirmed. In a minority of cases this further testing showed that the strains were not identical. In some instances a number of strains isolated from the same pair showed different combinations of the markers used.