Nationwide surveillance of drug-resistant tuberculosis in The Netherlands: rates, risk factors and treatment outcome.

SETTING: The Netherlands, 1993 and 1994. OBJECTIVE: To determine 1) rates of drug resistance in relation to nationality and country of birth, 2) risk factors for drug resistance, 3) treatment outcome of drug-resistant cases, and 4) rates of primary and acquired drug resistance. DESIGN: Retrospective study of all cases notified with bacillary tuberculosis in The Netherlands in 1993 and 1994. RESULTS: Drug resistance to one or more drugs was reported in 268 (14.6%) of all 1836 cases, of whom 203 (76%) were foreign born. In Dutch patients rates of isoniazid (H) (2.9%) and streptomycin resistance (3.6%) were lower than in foreign patients (8.6% and 10.6% respectively, P < 0.001). Multidrug (H and rifampicin [R]) resistance was reported in 0.5% of Dutch-born and 1.4% of foreign cases (P = 0.055). Rates of acquired resistance to H (11.4%) and HR (5.7%) were higher than rates of primary resistance to these drugs (5.2% and 0.7% respectively, P < 0.05), but the number of retreatment cases was low (6.8% of all cases). Drug resistance was associated with immigration but not with drug use, homelessness or human immunodeficiency virus (HIV) co-infection. One fifth (20%) of drug-resistant cases was diagnosed by active case finding. Treatment outcome in sensitive and resistant cases was compared. CONCLUSION: These findings suggest that drug resistance is imported, but it is unclear to what extent drug resistance among foreigners has been transmitted or created in The Netherlands. Drug resistance data should be monitored in Dutch and foreign patients separately.

Molecular epidemiology of infections with Neisseria gonorrhoeae among visitors to a sexually transmitted diseases clinic.

OBJECTIVES: To identify determinants for plasmid-mediated resistance to penicillin (penicillinase-producing Neisseria gonorrhoeae [PPNG]) and tetracycline (tetracycline-resistant N. gonorrhoeae [TRNG]) among gonococci, to determine the distribution of bacterial characteristics, and to correlate these with antibiograms and patient characteristics. STUDY DESIGN: Gonococcal isolates from 131 patients attending a sexually transmitted diseases clinic in The Netherlands in 1994 were auxotyped and serotyped and antimicrobial susceptibility was tested. Information on patient characteristics was collected at the initial visit. RESULTS: The most prevalent serotype, IB-1 (26%), proved to be related to sexual contact with casual partners, especially commercial sex partners. In addition, IB-1 strains were associated with PPNG and displayed higher minimum inhibitory concentrations (MICs) for ceftriaxone, cefuroxime, and ciprofloxacin. Homosexual men were more often infected with nonrequiring, IB-2, and IB-6 strains than heterosexuals. These strains were very sensitive to ceftriaxone and ciprofloxacin. Overall, one strain showed decreased susceptibility to ciprofloxacin (MIC 0.5 microgram/ml), but no resistance to ceftriaxone, ciprofloxacin, or cefuroxime was observed. However, 31% of the isolates were TRNG, PPNG, or both. Determinants for these resistant strains among men were the use of antibiotics (odds ratio [OR] = 4.8, 90% confidence interval [CI] 1.3-19.1), Surinam or Morrocan origin (OR = 3.3, 90% CI 1.3-8.4), and homosexual contacts (OR = 0.1, 90% CI 0.03-0.4). CONCLUSIONS: Different types, with variable susceptibility, were associated with homosexual and commercial sexual behavior. PPNG and TRNG were more commonly isolated from antibiotic users, heterosexual individuals, and ethnic minorities. Continuous surveillance of susceptibility is needed to follow the spread of PPNG and TRNG and to detect resistance to the currently recommended agents in a timely fashion.

Penicillin-resistant Streptococcus pneumoniae in the Netherlands: results of a 1-year molecular epidemiologic survey.

The molecular epidemiologic characteristics of penicillin-resistant pneumococci in the Netherlands were investigated in 1995. Dutch electronic surveillance data showed that 0.7% of all pneumococci were intermediately resistant and 0.4% were highly resistant to penicillin. From March 1995 to March 1996, 89 penicillin-resistant isolates were collected by 39 medical microbiology laboratories. Thirty different genotypes were observed by restriction fragment end labeling. Twenty-one DNA types were unique, whereas 9 distinct genotypes were shared by > or = 2 isolates. Different serogroups were found within 6 of the 9 genetically identical clusters of penicillin-resistant isolates, suggesting that horizontal transfer of capsular genes is common. Finally, nosocomial transmission of penicillin-resistant pneumococci was observed among 21 elderly adults with chronic obstructive pulmonary disease. This study demonstrates that multiple clones of penicillin-resistant pneumococci have been introduced in the Netherlands, a country with a low prevalence of pneumococcal infection. Some clones spread among the population in and outside hospitals.

Surveillance of antibiotic resistance in Neisseria gonorrhoeae in The Netherlands, 1977-95.

OBJECTIVE: To evaluate the prevalence and epidemiology of penicillinase producing Neisseria gonorrhoeae (PPNG) and tetracycline resistant N gonorrhoeae (TRNG) in the period 1977-95 in the Netherlands. To compare auxotypes, serovars, and antibiograms of PPNG, non-PPNG, and TRNG. To identify determinants in patient characteristics for the epidemic spread of TRNG/PPNG. METHODS: With respect to the national gonococcal surveillance all PPNG isolates from 30 laboratories over the country in 1977-90 and all gonococcal isolates from five sentinel laboratories (during 1 month per quarter) in 1991-5 were collected. Isolates were auxotyped and serotyped, the susceptibility for various antibiotics was tested and plasmid contents were evaluated. Additional data on PPNG infected individuals were collected retrospectively during a microepidemic of TRNG/PPNG. Univariate and multivariate analyses were performed to identify risk factors for TRNG/PPNG infections. RESULTS: In 1995 an overall high prevalence of PPNG infection (27%) and TRNG among PPNG infection (24%) was found in the Netherlands. Importantly, PPNG were found to have higher MICs for ceftriaxone and ciprofloxacin than non-PPNG; clinically relevant resistance to these antibiotics (or related agents) may emerge first among these strains. The observed diversity of strains (123 auxo/serovar classes since 1988) indicates a continuous introduction of new strains into the community. The epidemic increase of TRNG/PPNG was mainly caused by A/S classes NR/1B-6, PRO/1A-3, and PRO/1A-6, suggesting a clonal spread of a few strains; the rapid spread was associated with transmission in high risk individuals (that is, prostitutes and their clients). CONCLUSION: The prevalence of PPNG in the Netherlands remains high and reduced sensitivity to other antimicrobials was detected among the PPNG strains. This underlines the necessity for a continuous national surveillance of resistance in gonococci including limited epidemiological information.

[Drug resistance in Mycobacterium tuberculosis in The Netherlands]. / Resistentie bij Mycobacterium tuberculosis in Nederland.

OBJECTIVE: To determine magnitude, trend and specific features of the resistance problem. DESIGN: Descriptive. SETTING: Royal Netherlands Tuberculosis Association, The Hague, the Netherlands. METHODS: The data of the National Institute of Public Health and Environmental Protection concerning the prevalence of drug-resistant tuberculosis during the period 1990-1994 were analysed. Also, features of patients with and without drug resistance were compared (Dutch National Tuberculosis Register: cohort 1993). RESULTS: Isoniazid and streptomycin resistance were each observed in approximately 6% of susceptibility tests, showing no clear trend over the study period. Rifampicin resistance increased from 0% to 1.5% in 1994. In the 1993 patient cohort, 809 cases were analysed, showing resistant organisms in 103 (13%). The resistance group included 84 (82%) foreigners versus 387 (55%) among the 'sensitives' (p < 0.001). The percentages of (known) HIV infections were equal in both groups (5-6%). The percentage of isoniazid-resistance varied from 1.8% in Dutch patients to 7.8% in foreign patients. Recent immigrants and refugees waiting for official status were important risk groups for resistance (p < 0.005). Foreign tuberculosis patients defaulted more often from treatment than Dutch patients (p < 0.001). CONCLUSION: Drug-resistant tuberculosis in the Netherlands is mainly due to import of resistant strains. Transmission and further development of resistance within the country must be prevented.

In vitro susceptibility to antimicrobial drugs of 62 Salmonella strains isolated from horses in The Netherlands.

The in vitro activity of 17 antimicrobial drugs against strains of Salmonella typhimurium (n = 52), Salmonella thompson (n = 2), Salmonella heidelberg (n = 3), Salmonella hadar (n = 2), Salmonella enteritidis (n = 1), Salmonella infantis (n = 1) and Salmonella derby (n = 1) was tested using the agar dilution method. The strains were isolated from horses admitted to the Large Animal Clinics of Utrecht University. The majority of strains were susceptible to gentamicin, amikacin, kanamycin, enrofloxacin, ciprofloxacin, flumequine, colistine, furazolidone and ceftiofur. However, all strains of Salmonella typhimurium phage type 200 (n = 14), were multiresistant i.e. were resistant to ampicillin amoxycillin, amoxycillin in combination with clavulanic acid, chloramphenicol, nitrofurantoin, trimethoprim, aditoprim and baquiloprim. Two of these strains were also resistant to gentamicin. Based on the susceptibility data found in the present study in combination with pharmacokinetic data available in the literature a rationale for antimicrobial therapy in equine salmonellosis is given. As first choice, gentamicin at a dosage of 3 mg/kg combined with ampicillin at a dosage of 20 mg/kg given with a 8-12 hour dosing interval by intravenous route is advised. As an alternative, the intravenous administration of trimethoprim/sulfonamide combinations given twice daily at a combined dose of 30 mg/kg is suggested.

Disinfectant testing on surfaces.

During the last decade a consensus view has evolved in Europe on the quantitative testing of disinfectant efficacy in suspension tests, as well as in surface tests. Harmonization of the different national test methods is being pursued within the framework of the European Committee for Standardisation (CEN/TC216). An expert subgroup of the Committee has drafted a test method to measure the microbicidal activity of disinfectants on bacteria attached to surfaces. The outcome of an initial collaborative study from seven laboratories is that this test system yields reproducible results in different laboratories; thus fulfilling the requirements for a basic surface disinfectant test.

[Epidemic of penicillinase-producing, tetracycline-resistant gonococci; risk factors for their spread]. / Epidemie van penicillinase-vormende en tevens tetracycline-resistente gonokokken; risicofactoren voor de verspreiding.

OBJECTIVE: To assess whether the 1989 epidemic of tetracycline-resistant (TRNG) and penicillinase-producing Neisseria gonorrhoeae (PPNG) was caused by a small number of imported strains, and what the risk factors for infection were. DESIGN: Retrospective. SETTING: The National Institute of Public Health and Environmental Protection (NIPHEP). METHOD: A total of 1257 questionnaires were sent to the 5 microbiological laboratories which had contributed most to the number of isolates sent to NIPHEP, in order to obtain additional information of all patients infected in 1989 and 1990 with PPNG. Of all these patients the results of quantitative sensitivity testing, auxotype, serotype and plasmid pattern of the PPNG were obtained. RESULTS: The questionnaire response was 1047/1257 (83.3%). A part of the isolates from the non-responders was included in the study. Determinations were performed in 1185 PPNG isolates (94.3%). In 1988 and 1989 an increase of TRNG among PPNG was observed. The PPNG isolates in 1989 (n - 472) and 1990 (n = 713) from 5 laboratories in Amsterdam. Rotterdam and The Hague, showed that the epidemic was caused mainly by the spread of three strains. NR/IB-6, PRO/IA-3 and PRO/IA-6. The introduction probably took place in The Hague in 1988 and import from abroad could not be confirmed. The TRNG risk was increased for men and women over 40 years and for men from The Hague and Rotterdam having contacts with prostitutes; the latter did not apply to Amsterdam. For women, a Turkish or Latin American nationality increased the TRNG risk. CONCLUSION: Because of the continuing threat of developing resistance and the instability of microbiological characteristics of gonococci, a continuous national surveillance is necessary, including information about risk factors for infection with resistant gonococci, to improve the control of the infection.

In vitro susceptibility of equine Salmonella strains to trimethoprim and sulfonamide alone or in combination.

The in vitro activity of trimethoprim (TMP) and 9 sulfonamides and their combinations in 6 concentration ratios was tested against 62 Salmonella strains isolated from horses over a 3-year period in the Netherlands, using the agar-dilution method. Most of the isolates were S typhimurium strains (n = 52); the others were S heidelberg (n = 3), S hadar (n = 2), S thompson (n = 2), S enteritidis (n = 1), S infantis (n = 1), and S derby (n = 1). The minimal TMP concentration at which 50% of the Salmonella strains were inhibited (MIC50) was 0.12 micrograms/ml. Sulfachlorpyridazine (SCP; MIC50, 16 micrograms/ml), sulfamethoxazole (SMX; MIC50, 32 micrograms/ml), and sulfadiazine (SDZ; MIC50; 32 micrograms/ml) were the most potent of the sulfonamides tested. The antimicrobial effect of the sulfonamides, in combination with TMP (additive, synergistic, or antagonistic), was expressed by the fractional inhibitory concentration (FIC) index. Concentrations of SDZ and SCP with TMP had marked synergism at all tested TMP-to-sulfonamide concentration ratios (1:1 to 1:160; FIC index, 0.10 to 0.50); SMX had synergy with TMP at all ratios, except 1:1 (FIC index, 0.10 to 0.27). Sulfamethazine, sulfamerazine, sulfadoxine (SDX), sulfatroxazole, sulfadimethoxine, and sulfacetamide had MIC50 greater than their breakpoint MIC value and are, therefore, less potent drugs. However, synergy with TMP was found for these less potent sulfonamides at certain concentration ratios, depending on the sulfonamide used. Sixteen Salmonella strains were resistant to TMP, all sulfonamides, and TMP-sulfonamide combinations; 14 of these strains were S typhimurium phage type 200, 1 was S typhimurium phage type 61, and 1 was S typhimurium phage type 10.(ABSTRACT TRUNCATED AT 250 WORDS)

Establishment of a microbiologically acceptable daily intake of antimicrobial drug residues.

A model is presented to calculate the microbiologically acceptable daily intake (ADIm) of antibiotic residues in food products. The ADIm calculation is based on MIC values for indicator bacteria Escherichia coli, Bacteroides fragilis, Bifidobacterium spp. and Eubacterium spp., established under gut-like conditions in an in vitro simulation model. The maximum residue level (MRL) for residues in food products can be derived from the ADIm. Four phases can be distinguished in this gastro-intestinal simulation model, namely: 1. In vitro determination of the MIC for each bacterial strain by a standard method. 2. Incorporation of the drug into food (meat, milk) followed by testing of the stability of the antibiotic under gut-like conditions. 3. Adjustment of the 'gastric' fluid to the duodenal situation, inoculation with the test bacteria and anaerobic incubation at 37 degrees C for at least 18 h. 4. MIC reading confirmed by counting bacteria growing on specific solidified media. In this study the method for calculation of ADIm and MRL is given for flumequine as model drug. On the basis of MIC50 values for E. coli strains, a MRL for flumequine of 1.0 microgram/g meat or 0.25 microgram/ml milk was calculated. It is suggested that, depending on the antibacterial spectrum of the antibiotic involved, the ADIm can be determined with selected indicator bacteria, incubated under simulated gastrointestinal conditions.

A hospital outbreak of penicillin-resistant pneumococci in The Netherlands.

Respiratory infections with penicillin resistant pneumococci constitute an increasing health care problem. This paper describes the nosocomial spread of penicillin resistant pneumococci (PRP) on a pulmonary ward. During an eight-month period, minimal inhibitory concentrations (MICs) for penicillin and several other antibiotics were performed on all Streptococcus pneumoniae isolates that were shown to be penicillin resistant by a screening assay. The personal data and case history of all patients with penicillin resistant pneumococci were evaluated. Penicillin Resistant Pneumococci were cultured from 18 patients, 16 men (mean age 74 +/- 8 yrs) and 2 women (aged 54 and 60 yrs). Chronic obstructive pulmonary disease was diagnosed in 16 patients, 10 of which had an additional underlying disease (2 diabetes mellitus, 2 heart failure, 2 malignancy). Prior to culture of Penicillin Resistant Pneumococci, 11 out of 18 patients were treated with antibiotics, a beta-lactam in most instances. Ten out of 18 patients died during or shortly after hospitalization. The death of one patient seems to be directly related to infection with Penicillin Resistant Pneumococci. The five Penicillin Resistant Pneumococci isolates available for serotyping were all type 9. The minimal inhibitory concentrations for penicillin varied from 0.5 to 2.0 mg.l-1. High minimal inhibitory concentrations were also noted for cefixime (all over 4.0 mg.l-1) and ceftriaxone (0.5-1.0 mg.l-1). It is concluded that penicillin resistant pneumococci can spread rapidly among old and debilitated patients. Thus, patients with this infection should be barrier nursed.

A multicenter survey of resistance in The Netherlands using the Etest.

To obtain data about the prevalence of resistance in bacterial isolates causing serious infections in the Netherlands, a multicenter survey was carried out using the Etest for quantitative susceptibility testing. More than 6000 isolates belonging to ten species were tested against eight antibiotics. Moreover, the Etest was validated against the agar dilution method and the reproducibility of the Etest was studied. In spite of pH differences between the agar plates used for Etesting and agar dilution testing, a good correlation (that is 86%-97% within log2 dilution steps) was found between both methods. Comparison of Etest values of the participating laboratories and the reference laboratory showed > 80% conformity within 1 log2 dilution step and 90% within 2 log2 dilution steps, indicating a sufficient reproducibility of the Etest. Resistance percentages were low for most species and antibiotics, relatively high percentages (10%-20%) indicating natural insusceptibility rather than development or increase of resistance.

Prevalence of fluoroquinolone resistance in Europe. Study Group 'Bacterial Resistance' of the Paul-Ehrlich-Society for Chemotherapy e. V.

Since 1984, when the first fluoroquinolone, norfloxacin, was marketed in Europe, there has been a marked increase in the usage of this class of drugs. In order to evaluate the influence of this drug usage on the prevalence of resistance to fluoroquinolones in clinical isolates of the family Enterobacteriaceae, Pseudomonas aeruginosa, Staphylococcus aureus, coagulase-negative staphylococci and Enterococcus faecalis we reviewed the susceptibility data from four collaborative surveys conducted between 1983 and 1990 by the Study Group 'Bacterial Resistance' of the Paul-Ehrlich-Society for Chemotherapy. All participating laboratories used the same standardized methods. Minimal inhibitory concentrations were determined by the broth microdilution method. More than 20,000 bacterial strains were tested. The results are presented for ciprofloxacin, which is regarded as the representative of the fluoroquinolones. Using > or = 4 mg/l as a breakpoint for resistance to ciprofloxacin, the prevalence of resistant strains of the family Enterobacteriaceae in Central Europe between 1983 and 1990 remained below 1%. In contrast, the resistance rates in P. aeruginosa were 0.7%, 1.0%, 3.8% and 7.0%, in S. aureus 0%, 0.5%, 6.6% and 6.8%, and in E. faecalis 2.2%, 0.7%, 4.9% and 7.7% in 1983, 1986, 1989 and 1990, respectively. The latest study carried out in cooperation with 78 laboratories from 12 European countries revealed great differences in the prevalence of resistance to fluoroquinolones from one species to another ranging from 0% with Proteus vulgaris and Salmonella spp. to 26.7% with Providencia stuartii.(ABSTRACT TRUNCATED AT 250 WORDS)

An evaluation of the repeatability and reproducibility of a surface test for the activity of disinfectants.

A collaborative study was carried out to determine the precision of a disinfectant surface test method which is currently under consideration for development as a harmonized European standard surface test. Results indicate that significant variation in microbicidal effect occurs both within and between test laboratories despite careful standardization of test conditions, but that the variability may be less than that associated with suspension tests. Indications are that much of this variability derives from random variations in the resistance of the test strains from day to day and, most particularly, from test period to test period both within as well as between laboratories. It is concluded that although the test may be sufficiently reliable to be used as a standard method, adequate replication must be specified to distinguish borderline pass from borderline fail concentrations.

In-vitro susceptibility to antimicrobial drugs of bacterial isolates from horses in The Netherlands.

Minimum inhibitory concentrations (MICs) of 30 antimicrobial agents (including the hitherto unreported antimicrobial agents doxycycline, minocycline, vanomycin, 3 quinolones and 3 combinations of antimicrobial agents) for isolates of Salmonella spp. (20), Escherichia coli (17), Klebsiella spp. (8), Proteus spp. (7), Pseudomonas aeruginosa (7), Actinobacillus equuli (5), Rhodococcus equi (4), Streptococcus zooepidemicus (23), Streptococcus equisimilis (6), Streptococcus equi (4), coagulase-positive Staphylococcus spp. (20) and Taylorella equigenitalis (19) were determined using the agar dilution method. All isolates were of equine origin. MICs were compared with recommended MIC breakpoints. The results indicate that, for some of the pathogenic bacteria evaluated, susceptibility testing of isolates from the individual patient is essential to determine an appropriate antimicrobial treatment.

Impaired immune response by isoniazid treatment during intravesical BCG administration in the guinea pig.

At present, isoniazid (INH) is being used prophylactically to reduce the side effects of intravesical BCG therapy for superficial bladder cancer, although it is not clear whether or not this reduces the antitumor efficacy of BCG. In this study the impact of INH treatment on the immune response after repeated intravesical BCG administration was investigated in guinea pigs. INH was given on the 3 days around each BCG instillation. We found that the administration of INH severely impaired the immunological effects of BCG. The induction of mononuclear cell infiltration in the bladder wall was reduced. Enlargement of the regional lymph nodes (weight and number of cells), and increase of MHC Class II expression on the lymph node cells, normally observed after intravesical BCG administration, were inhibited by INH. Systemic immunity, measured by the DTH reaction in the skin to PPD, was also diminished due to the combined treatment of BCG with INH. When INH was administered during the last 4 of 6 BCG instillations, the immune response to BCG was still impaired. A five-fold increase of the dose of BCG did not overcome the effect of INH. INH probably did not exert a direct suppression of the immune system of the guinea pig as the DNCB skin reactivity was not influenced. Although INH concentrations in the urine were high at the onset of the instillation, in vitro experiments indicated that the effect of INH may not be caused by killing of the BCG organisms shortly after application in the bladder. In conclusion, our data in guinea pigs suggest that the use of INH may impair the immune response to intravesical BCG. As this response may be important for the antitumor effect of BCG, urologists should be cautious with the prophylactic use of INH. The influence on the antitumor efficacy is now investigated in man.