Surveillance of invasive Streptococcus pneumoniae infection in the province of Quebec, Canada, from 1996 to 1998: serotype distribution, Antimicrobial susceptibility, and clinical characteristics.

In the province of Quebec, Canada, from 1996 to 1998, 3,650 invasive Streptococcus pneumoniae infections were reported. A total of 1,354 isolates were serotyped and tested for antimicrobial susceptibility. The distribution of serotypes remained stable over the 3 years, with serotypes 14, 6B, 4, 9V, 23F, and 19F accounting for 61% of the isolates. Overall, 90% of isolates were included in the current 23-valent vaccine and 67% were included in the 7-valent conjugate vaccine. We were able to determine that resistance to penicillin and to other antibiotics is increasing.

Use of an oxacillin disk screening test for detection of penicillin- and ceftriaxone-resistant pneumococci.

In a context of worldwide emergence of resistance among Streptococcus pneumoniae strains, early detection of strains with decreased susceptibility to beta-lactam antibiotics is important for clinicians. If the 1-microgram oxacillin disk diffusion test is used as described by the National Committee for Clinical Laboratory Standards, no interpretation is available for strains showing zone sizes of /=2.0 microgram/ml) to penicillin. For ceftriaxone, among 98 strains with no zone of inhibition in response to oxacillin, 68 had intermediate resistance (MIC, 1.0 microgram/ml), and 22 were resistant (MIC, >/=2.0 microgram/ml). To optimize the use of the disk diffusion method, we propose that the absence of a zone of inhibition around the 1-microgram oxacillin disk be regarded as an indicator of nonsusceptibility to penicillin and ceftriaxone and recommend that such strains be reported as nonsusceptible to these antimicrobial agents, pending the results of a MIC quantitation method.

Susceptibility of group A beta-hemolytic streptococci in the lower St Lawrence region, Quebec.

OBJECTIVE: To determine the susceptibility of group A beta-hemolytic streptococci (GABHS) in the lower St Lawrence region, Quebec to different antibiotics, particularly macrolides, and to compare different antibiogram methods (disk diffusion, E-test and microdilution) and incubation atmospheres (ambient air and 5% carbon dioxide). METHODS: A total of 384 strains of GABHS isolated from 377 patients (throat 335; other sites 49) from three hospitals in the lower St Lawrence region were analyzed for their susceptibility to erythromycin, clarithromycin, azithromycin, penicillin, clindamycin, cephalothin, rifampin and vancomycin by disk diffusion on Mueller-Hinton (MH) agar supplemented with 5% defibrinated sheep blood (MHB) at 35ºC in 5% carbon dioxide. Strains that were found to be intermediately resistant or resistant to one of the antibiotics by disc diffusion, strains from sites other than throat, and a sample of 97 pharyngeal strains were evaluated by E-test on MHB (35ºC, 5% carbon dioxide) for their susceptibility to the antibiotics erythromycin, clarithromycin, azithromycin, penicillin, clindamycin and ceftriaxone. In addition, minimum inhibitory concentrations (MICs) were determined for erythromycin and azithromycin by broth microdilution using MH broth supplemented with 2.5 % of lysed horse blood (35ºC, ambient air) on strains that were resistant or intermediately resistant to the macrolides (erythromycin, clarithromycin, azithromycin). An evaluation was also carried out on these strains to determine the influence of the incubating atmosphere (ambient air versus 5% carbon dioxide) on susceptibility results obtained by disk diffusion (erythromycin, clarithromycin and azithromycin) and E-test (erythromycin and azithromycin) methods. RESULTS: Nine strains (2%) from nine patients (throat eight, pus one) were resistant to all macrolides as tested by three different techniques (disk diffusion, E-test and microdilution). All strains were susceptible to all the other antibiotics tested. For the strains intermediately resistant or resistant to macrolides, incubation in a 5% carbon dioxide atmosphere was associated with a reduction in the diameter of inhibition determined by disk diffusion (P<0.001) with frequent minor variations in interpretation, and with an increase in the MIC by E-test (P<0.001), which had no impact on interpretation. CONCLUSIONS: Resistance of GABHS to macrolides was not common (2%) in the lower St Lawrence Region. GABHS susceptibility to erythromycin seemed to predict the susceptibility to the other macrolides. Significant variation in antibiogram results (disk diffusion and E-test) of GABHS susceptibility to macrolides was related to the incubation atmosphere and may have an impact on the interpretation of disk diffusion results.

Serogroup-specific epidemiology of Streptococcus pneumoniae: associations with age, sex, and geography in 7,000 episodes of invasive disease.

A study sample of 7,010 episodes of invasive Streptococcus pneumoniae disease was obtained by combining 13 existing datasets. Disease episodes due to each of 12 pneumococcal serogroups (1, 3-9, 14, 18, 19, and 23) were then compared with episodes in a constant internal control group to describe serogroup-specific variations in disease frequency by age, sex, and geographic origin. The results are presented as odds ratios (with 95% confidence intervals) derived by logistic regression, with adjustment for the major confounders, including dataset of origin. Variation in the male:female ratios between serogroups is small, suggesting that capsular characteristics are an unlikely explanation for the male preference of S. pneumoniae. Serogroups associated with higher nasopharyngeal prevalence (e.g., 19 and 24) are relatively more common in Europe and North American, while the invasive serotypes 1 and 5 are much more common in South America. The custom of reporting serogroup frequencies in two age groups, children and adults, conceals much of the variation in the age distributions across the whole span of life. The reduction of risk associated with serogroups 6, 14, 18, 19, and 23 beyond childhood follows different gradients, being most abrupt in serogroups 14 and most gradual in serogroup 18. The relative risk of disease with serotype 1 declines steadily throughout life, while with serotypes 3 and 8 it increases over middle age. Serogroups 7 and 23 are found unusually frequently in the third decade of life. Because of the wide differences in the epidemiology of individual serogroups of S. pneumoniae, it is questionable whether pneumococcal infection should continue to be classified as a single disease entity.

Evaluation of three glutaraldehyde-based disinfectants used in endoscopy.

The European suspension test was applied to compare the in vitro activity of three glutaraldehyde-based disinfectants: a 1:10 dilution of a 10% glutaraldehyde solution containing 0.5% phenylphenol-0.1% amylphenol, a 2% acid glutaraldehyde solution, and a 2% alkaline glutaraldehyde solution. The microbicidal effect of the disinfectants was evaluated by counting surviving cells of three indicator microorganisms (Pseudomonas aeruginosa, Mycobacterium chelonae and phage f2) after exposure times of 5, 10, 20 and 40 min to the agents at 20 degrees C. An inactivation factor (IF) of > or = 5 log10 was used as the criterion for effective disinfection. This IF was achieved with every microorganism/disinfectant combination after 5 min exposure except in experiments with phage f2 and the 1% glutaraldehyde-based disinfectant. The diminished inactivation noticed with the 1% glutaraldehyde-based disinfectant supports the recommendation to use a disinfectant containing a minimum of 2% glutaraldehyde for high level disinfection.

Pneumococcal resistance to antimicrobial agents in the province of Québec, Canada.

The serogroup/serotypes (SGTs) and antimicrobial susceptibilities to 10 antimicrobial agents of 110 clinical strains of Streptococcus pneumoniae were determined. Strains intermediately resistant or highly resistant to penicillin G (80 of 110) belonged predominantly to SGTs 23 (45.0%), 19 (13.7%), 6 (10.0%), 9 (6.2%), and 14 (3.7%). The MICs of all cephalosporins, tetracycline, trimethoprim-sulfamethoxazole, and chloramphenicol increased along with the MICs of penicillin G. However, erythromycin resistance and clindamycin resistance were observed more frequently among the intermediately penicillin-resistant strains. Multiple resistance was observed for 32 strains, of which 25 were highly resistant to penicillin G and belong to SGT 23F. All strains were susceptible to vancomycin.

Evaluation of a mechanical/chemical infectious waste disposal system.

OBJECTIVES: The mechanical/chemical infectious waste disposal system (IWDS), model Z-5000 HC, manufactured by Medical SafeTEC Inc. (Indianapolis, Indiana) was evaluated for its ability to disinfect biomedical waste. METHODS: The IWDS was operated with a sodium hypochlorite solution and tested with loads consisting of microbial cultures and blood. During and after processing, samples of liquid, milled solid waste, and leachate were collected to determine the efficacy of disinfection and the chemical by-products released. An inactivation factor was calculated. Aerosol emission was studied. All tests were done in triplicate. RESULTS: Our results showed the expected level of disinfection (inactivation factor greater than or equal to 5 log10) for all tests carried out with Bacillus subtilis, Enterococcus faecalis, Candida albicans, and Serratia marcescens, and for most of the tests with Mycobacterium fortuitum and bacteriophages OX174 and f2. Further tests performed in the absence of blood resulted in an inactivation factor greater than or equal to 5 log10 for all tests with M fortuitum, but not for those of the milled solids with bacteriophage f2. Aerosols were found to escape the apparatus when the IWDS was operated in the absence of chlorine. The liquid effluent contained an average of 17,600, and 15 mg/l of free chlorine, chloramines, and trihalomethanes (THM), respectively. The air effluent contained 1.1 mg/m3 of total chlorine and 1.4 micrograms/m3 of THM. CONCLUSIONS: Under our study conditions and except for certain tests with bacteriophage f2, the IWDS reduced the microbial populations tested by a factor of 5 log10. The aerosol dispersion problem remains to be solved, and the significance of the chemical by-products released will require further investigation.

Surveillance of invasive Streptococcus pneumoniae infection in Quebec, Canada, from 1984 to 1986: serotype distribution, antimicrobial susceptibility, and clinical characteristics.

Four hundred and sixty-eight strains of Streptococcus pneumoniae isolated from blood or normally sterile body fluids in 14 Quebec, Canada, hospitals between 1 July 1984 and 31 December 1986 were serotyped, their susceptibilities to antimicrobial agents were determined, and the laboratory data were correlated with the clinical information. The distribution pattern of the serogroups and serotypes was similar to that observed previously in Quebec and to that in other parts of Canada and in the United States. No regional variation was observed. The distribution of serogroups and serotypes was different in pediatric patients (less than 18 years old) when compared with that of adults (P less than 0.001). Overall, 94% of the strains were represented in 23-valent vaccine. The total mortality rate was 12.8% and increased with age: 1.6% in pediatric patients, 14.8% in patients 18 to 64 years old, and 31% in those greater than or equal to 65 years old (P less than 0.001). In patients 18 to 64 years old, the mortality rate was higher when an underlying condition that could have justified prior vaccination was present (P = 0.008). In patients greater than or equal to 65 years old, the mortality rates were similar in those with and those without underlying conditions, suggesting that vaccine use in all patients greater than or equal to 65 years old might be appropriate. Only six patients had received pneumococcal vaccine before infection. Only 15 strains (3.2%) were moderately susceptible or resistant to one or more of the antimicrobial agents tested. Six strains were moderately susceptible to penicillin G, and none was fully resistant.

Evaluation of two hot water washer disinfectors for medical instruments.

Two models of hot water washer disinfectors (Decomat 128 and Hospital A, Euroclean Canada Inc; Ontario, Canada) were evaluated by two methods for their efficacy in disinfecting anesthesia equipment. In the first method, three different microbial suspensions were each sealed into 30 capillary tubes. In the second method, corrugated anesthesia tubes were rinsed with suspensions of each of two bacterial strains. The tubes then underwent a standard cycle in the hot water washer disinfectors and were subsequently tested for growth of microorganisms. All experiments were repeated three times, and the temperature was registered in all cases. In the capillary test, growth was rarely detected (13/540 tubes) and the inactivation factor for both apparatus was greater than 5 log10. In the rinse test, no growth was detected. The mean temperature for 15 disinfection cycles was 84.2 +/- 0.8 degrees C for Decomat 128 and 88.9 +/- 0.5 degrees C for Hospital A. However, for Decomat 128 we observed a variation of 3 degrees C from one disinfection cycle to another and a progressive reduction of 2.2 degrees C over a series of five consecutive complete cycles. Both methods gave reproducible results. Under our experimental conditions, both hot water washer disinfectors proved to be efficacious for the disinfection of reusable anesthesia equipment.

Phage types of Staphylococcus aureus received at the Quebec Public Health Laboratory from 1976 to 1983.

Phage typing of 13,579 clinical and environmental strains of Staphylococcus aureus received at the Quebec Public Health Laboratory between 1976 and 1983 was routinely performed to assess the distribution of lytic groups. Strains susceptible to phages 94, 95, and 96 predominated and accounted for 25% of the specimens. The distribution of strains in lytic groups varied with time and specimen source.

[An automatic bacteriophage distributor (author's transl)]. / Un distributeur automatique de bactériophages.

The apparatus described in this article can distribute simultaneously 22 drops of different phage suspensions at a rate of 13,200 drops per hour, which is superior than the one obtained with the presently available apparatuses. It could eventually be attached to a Petri dish distributor.

[Risk of contamination by pipetting bacterial culture broth with "Pasteur pipettes" (author's transl)]. / Danger de contamination lors de prélèvements de suspensions bactériennes par "pipettes Pasteur".

Our experiments have shown that the cotton plug located at the top end of a "Pasteur pipette" allows aerosol to escape upon aspiration of a bacterial culture broth and may be the cause of contamination. In the following, we propose the use of a bacteriological filter system which insures greater safety.