Survey Of Antimicrobial Resistance Research Articles

A national survey of antimicrobial resistance in Staphylococcus aureus in Australian teaching hospitals.

An extensive survey of the in-vitro susceptibility of clinical isolates of Staphylococcus aureus to 18 antimicrobial agents was conducted over three separate periods during 1986-1987 in 14 teaching hospitals in major Australian cities. The survey aimed to document the prevalence of resistance to a wide variety of drugs that are important as antistaphylococcal agents or as epidemiological markers. More than 7500 isolates were examined. Nationally, the prevalence of resistance was 85.3% to penicillin G, 14.4% to methicillin, 14.0% to amoxycillin/clavulanate, 9% to cephalothin, 5.4% to cephamandole, 9.9% to cefotaxime, 25.0% to erythromycin, 11.2% to clindamycin, 21.7% to tetracycline, 13.0% to gentamicin, 1.9% to amikacin, 5.8% to chloramphenicol, 18.3% to trimethoprim, 0.6% to rifampicin, 3.0% to fusidic acid and 1.2% to novobiocin. For none of the strains was resistance to vancomycin confirmed by minimal-inhibitory-concentration determination. A high proportion of the resistances was harboured in methicillin-resistant Staph. aureus, except for resistance to penicillin G, erythromycin and tetracycline. The prevalence of methicillin resistance varied widely among the states: 25.2% in Queensland, 23.5% in Victoria, 12.6% in New South Wales/the Australian Capital Territory, 11.3% in South Australia and 0.4% in Western Australia. Isolates from blood cultures were slightly-more susceptible to antimicrobial agents than were isolates from other body sites. Six common profiles of resistance to penicillin G, methicillin, erythromycin, clindamycin and tetracycline accounted for more than 95% of the isolates that were tested against all five agents. Vancomycin remains the most important antistaphylococcal drug in areas where resistance to methicillin is common.

A seventeen-year epidemiological survey of antimicrobial resistance in pneumococci in two hospitals

During a 17 year period (1970-1986), 2753 clinical isolates of Streptococcus pneumoniae isolated in two hospitals were serotyped and tested for antibiotic susceptibility. In the last ten years the number of multiply resistant strains has increased to 60% of the resistant isolates. Resistance to tetracycline was already present in 14% of the isolates in 1970, and was the most frequent resistance encountered during this study (30% of the strains). Resistance to chloramphenicol was first detected in 1972, but this resistance has remained infrequent (3%). Resistance to penicillin is extremely rare and since 1978, only six strains with relative penicillin resistance (MIC 0.1-1.0 mg/l) have been isolated. Resistance to macrolides, lincosamides and streptogramin B (MLSB resistant phenotype) was first detected in 1976. From 1983 to 1986, 131 isolates were MLSB resistant strains. These strains belonged to 20 different serotypes but 75% of the MLSB resistant pneumococci belonged to serotypes 6, 23, 19 and 14 which were among the most frequently isolated serotypes. In contrast serotypes 3 and 9 were epidemic but not resistant during the same period. Resistance markers in S. pneumoniae are often related to particular serotypes. The large monthly fluctuation in the isolation of resistant strains might explain the variable clinical results of empirical treatment of respiratory infections with macrolides.

Survey of antimicrobial resistance in lactic streptococci.

A total of 26 strains of Streptococcus cremoris and 12 strains of Streptococcus lactis were challenged with 18 antimicrobial agents and with nisin in the Bauer-Kirby disk susceptibility test. All strains were susceptible to ampicillin, bacitracin, cephalothin, chloramphenicol, chlortetracycline, erythromycin, penicillin G, tetracycline, and vancomycin. All strains were resistant to trimethoprim, and almost all strains were resistant to sulfathiazole. Variability in resistance to gentamicin, kanamycin, lincomycin, nafcillin, neomycin, nisin, rifampin, and streptomycin was observed. MICs of these substances for the less susceptible strains were determined, and high-level resistance factors could not be detected, except in the case of nisin. S. lactis ATCC 7962 was resistant to at least 40-fold-higher concentrations of nisin (greater than 64 micrograms/ml) than most other strains tested. This strain was a potent nisin producer.