Recent trends on bacterial resistance to antibiotics.

Antimicrobial resistance has become a major medical and public health problem. The main factor responsible for development and spread of bacterial resistance is injudicious use of antimicrobial agents which has resulted in most gram positive and gram negative bacteria continuously developing resistance to the antimicrobials in regular use at different time periods. In East Africa, among E. coli in urinary tract infections, more than 80% are currently resistant to ampicillin, cotrimoxazole and tetracycline while more than 80% of the isolates are still susceptible to nitrofurantoin, gentamicin and third generation cephalosporins. Penicillin G resistant strains of pneumococci were first reported in 1967 but had gradually increased to about 20% in 1991. Among group A streptococci, all natural strains are still sensitive to penicillin G while resistance to tetracycline has reached alarming proportions. In Tanzania, more than 65% of N. gonorrhoeae isolates are beta-lactamase producers, however, spectinomycin, second and third generation cephalosporins and ciprofloxacin are effective against most strains. Vibrio cholerae 01 strains resistant to multiple antibiotics are widely spread globally, however, there are recent reports indicating that withdrawal of the drugs can lead to loss of the antibiotic resistance factors. Despite varied susceptibility of N. meningitidis strains world wide, isolates in Tanzania are still susceptible to commonly available drugs including penicillin G and chloramphenicol. Available methods for control of spread of bacterial resistance include rational use of antimicrobial agents including control in animal husbandry, change to newer antimicrobials, rotational use of drugs and constant surveillance for emerging bacterial resistance.