Infectious diseases

Drug-resistant bugs raise concern

Organisms that have developed antimicrobial resistance are quickly becoming a global issue, but there are few data on the prevalence, patterns of resistance and risk factors associated with resistant organisms in children.

Researchers tested isolated cultures of Escherichia coli (E. coli) taken from the urinary tracts of 967 children with urinary tract infections who were treated at the Children's Hospital of Eastern Ontario between December 1992 and December 1994. They found that 45% of the isolates were resistant to ampicillin and 31% were resistant to trimethoprim-sulfamethoxazole, both important first-line therapies. They further determined that children admitted to hospital one or more times in the previous year were more likely to have resistant isolates than those with no admissions in the previous year.

The authors recommended that children who have had multiple admissions to hospital and/or have been prescribed a specific antimicrobial drug have their antimicrobial regimens reassessed periodically. Possible options are to alternate drugs or to exclude certain drugs for long periods. [CMAJ 1999;160(10):1436-40]

Hepatitis B on the street

The lifestyle of street youths puts them at increased risk of STDs and blood-borne infections. A 1996 cross-sectional anonymous study of 437 youths aged 14 to 25 years was held to determine hepatitis B markers and risk behaviours among Montreal street youth. The authors report that 45.8% had injected drugs, 24.5% had engaged in prostitution and 8.7% reported having a sexual partner with unspecified hepatitis. Overall, the prevalence rate of HBV markers was 9.2%. The authors suggest that since Montreal street youth are at high risk for infection, early and complete HBV vaccination among this population is urgently needed. [CMAJ 1999;161(6):689-93]

HIV antiretroviral regimen promising

A new population-based study moves beyond the highly controlled environment of the randomized clinical trial and shows that patients treated with triple-drug therapy also fare considerably better in the real world. The BC researchers followed 500 men and women infected with HIV; some patients received two antiretroviral drugs and some received three drugs. The researchers found that the likelihood of progression to AIDS or death after one year was more than two times higher in the group receiving two drugs compared with those receiving three drugs. [CMAJ 1999;160(5):659-65]

An accompanying editorial emphasized that only studies of this type actually help physicians and patients understand the importance of proper treatment for HIV-infected patients. [CMAJ 1999;160(5):669-70]

Malaria risk

Canadians visiting India should beware of the risk of malaria. The world's most serious parasitic disease, malaria accounts for about 300 million cases and two million deaths annually. In 1997, 1036 cases were reported in Canada, and 30% to 80% of cases of imported malaria involved travelers to India. Despite this, a survey of 300 Canadians returning from India found that although two-thirds considered malaria a serious problem and over half had sought pretravel medical advice, only 31% intended to take measures to avoid getting the disease while in India. Only 7% had been prescribed a recommended drug regimen and less than 10% planned to follow measures to prevent insect bites. [CMAJ 1999;160(2):195-200]

Tuberculosis

Although tuberculosis is both treatable and preventable, it continues to withstand eradication efforts; 3.8 million cases of active TB were diagnosed worldwide in 1998. Although TB is fairly rare in Canada, with about 2000 cases reported annually, infection rates are much higher among natives and injection drug users, and immigrants and refugees from countries where TB is endemic. An editorial reminded physicians that with a disease that is 99% curable and 90% preventable, there is no excuse for complacency. [CMAJ 1999;160(6):837-9]

Researchers found that 31% of subjects recruited through a Toronto needle-exchange program tested positive for TB. The authors suggested that TB screening among injection drug users is feasible and provided suggestions for future programs. [CMAJ 1999;160(6):789-94]

However, another study found that the benefits accrued by vigilant screening were often lost since only 58% of those diagnosed with TB completed treatment, considerably lower than the World Health Organization's recommended rate of 85%. The authors used information from patient charts, the local health unit and the provincial Reportable Disease Information System to follow 145 patients with TB at five tertiary care centres in Toronto in 1992/93. They reported that injection drug use, HIV infection and adverse drug reactions were the main reasons why patients failed to complete treatment. [CMAJ 1999;160(6):799-802]

An accompanying editorial cautioned that optimal control of TB will only be possible when there is improved prescribing of appropriate antituberculosis treatment. The author also recommended improving communication between clinicians and public health agencies in order to track and follow up on patients who move and may discontinue treatment. [CMAJ 1999;160(6):821-2]

Tuberculosis and AIDS

Researchers studied the incidence of tuberculosis (TB) among the 4,684 people aged 15 years and over in Quebec who were diagnosed as having AIDS between Jan. 1, 1979, and Dec. 31, 1996. Of these, 242 (5.2%) had active TB at some time during their illness. Multivariate logistic regression analysis showed that AIDS patients born in HIV-endemic countries in the Caribbean, sub-Saharan Africa or other developing regions were 21.8 times, 17.9 times and 4.9 times, respectively, more likely to have TB than those born in Canada. It also showed that people who acquired HIV infection through heterosexual contact were 2.1 times more likely to have TB than men who acquired it through sexual contact with other men. [CMAJ 1999;160(13):1838-42]