False aminoglycoside resistance in Enterobacterales and non-fermenters by an automated testing system: a descriptive study.

IMPORTANCE: Antimicrobial sensitivity data are important to guide antimicrobial therapy. In microbiological laboratories, routine sensitivity measurements are typically performed with automated testing systems such as VITEK2 and Phoenix. Using data from the Dutch national surveillance system for antimicrobial resistance over a 6-year period, we found that the measured minimum inhibitory concentrations for aminoglycosides in Enterobacterales and non-fermenters were too high for the Phoenix system. In addition, we observed a yearly increase in resistance for several species measured by Phoenix. These findings might have consequences for clinical treatment of patients with sepsis.

Distribution of extended-spectrum beta-lactamase genes using a commercial DNA micro-array system.

Extended-spectrum beta-lactamase (ESBL) genes are distributed worldwide and their epidemiology is complex. Using the Check-ESBL assay, the distribution of class A ESBL genes in clinical isolates of aerobic Gram-negative bacilli from three laboratories in the East of The Netherlands was determined. Four patient categories were distinguished: (i) patients admitted to an intensive care unit (ICU); (ii) non-ICU inpatients; (iii) outpatients admitted less than a year before collection of the isolate, (<1); (iv) outpatients admitted more than one-year prior to isolate collection or who had never been hospitalized (>1). From February 2009 until March 2010, out of 491 putative ESBL-positive isolates detected by the Vitek2 or Phoenix automated sensitivity testing systems, ESBL genes were detected in 247 (50.3%) by the Check-ESBL assay. Of these, 116 were from hospitalized patients (35 ICU, 81 non-ICU) and 131 were from outpatients (43 <1, 88 >1). In all, 274 ESBL genes were identified in these 247 isolates: 153 CTX-M-1 group (predominantly in E. coli and K. pneumoniae, 70.4% and 51.6% respectively), 67 CTX-M-9 group (predominantly in E. cloacae, 57.9%), 32 SHV, 14 TEM and 8 CTX-M-2 group. ESBL-producing E. cloacae were significantly more common in hospitalized patients than in outpatients, 20.7% and 3.8% respectively (P=0.001). CTX-M-9 group ESBLs were significantly more prevalent in ICU patients (P=0.003), whereas SHV ESBLs were more common in hospitalized patients than in outpatients (P<0.001). There was no significant difference in distribution of ESBL genes between the two outpatient groups.

Increasing resistance to fluoroquinolones in escherichia coli from urinary tract infections in the netherlands.

In continuous surveillance of routine samples from five Dutch laboratories, we studied resistance to the antibiotics most commonly prescribed for urinary tract infections (UTI) in The Netherlands, namely norfloxacin, amoxycillin, trimethoprim and nitrofurantoin, from 1989 to 1998 in >90000 Escherichia coli isolates. Resistance to norfloxacin increased from 1.3% in 1989 to 5.8% in 1998. Multiresistance, defined as resistance to norfloxacin and at least two of the other three antibiotics, increased from 0.5% in 1989 to 4. 0% in 1998. Multivariate analysis of the norfloxacin resistance demonstrated that this yearly increase (the odds ratio was 1.0 in 1989, 1.6 in 1992, 2.9 in 1995 and 6.1 in 1998) was independent of other determinants of resistance to norfloxacin, such as age, gender and origin of the isolate. Analysis of strata, classified by year, age and gender, demonstrated an association between prescription of fluoroquinolones (defined daily doses per case of UTI) and resistance to norfloxacin in E. coli (P < 0.001). There was no significant association with the prescription of nitrofuran derivatives (nitrofurantoin) and trimethoprim with or without sulphamethoxazole. The yearly increase of resistance to fluoroquinolones in E. coli from UTI may stem from increased prescription of fluoroquinolones for UTI. Resistance of E. coli to these agents is likely to increase further as fluoroquinolone use increases in future.

[Rat bite fever after a bite from a tame pet rat]. / Rattenbeetziekte na een beet van een tamme huisrat.

A 43-year-old woman presented with a generalized febrile illness, an exanthema with mixed maculopapulous and pustulous eruptions on the lower halves of the extremities, elbows, knees, palms and soles. There was also severe arthralgia and asymmetric arthritis. The diagnosis was rat bite fever. The disease became manifest eight days after she was bitten by a pet rat. Rat bite fever can easily be missed, even after adequate anamnesis and physical examination, while the differential diagnostic considerations are numerous. Our patient was cured completely after intravenous administration of penicillin G. Antimicrobial therapy was completed by an oral course of doxycycline.

Resistance of staphylococci in The Netherlands: surveillance by an electronic network during 1989-1995.

An electronic surveillance network for monitoring antibiotic resistance in The Netherlands has been in operation since 1989. Seven public health laboratories participate and the system covers about 25% of all bacteriological determinations in The Netherlands. This paper reports the results of staphylococci isolated in the period 1989-1995. About 0.3% of the Staphylococcus aureus isolates in the study period were resistant to methicillin. This low percentage may be due to the restrictive use of antibiotics and to strict isolation measures aimed at eradicating methicillin-resistant S. aureus. Low frequencies of resistance among methicillin-resistant S. aureus were found for vancomycin (0%), chloramphenicol (11%), cotrimoxazole (11%), mupirocin (3% low-level resistance) and fusidic acid (7%). Twenty-one percent of the coagulase-negative staphylococci were resistant to methicillin. Low frequencies of resistance among these methicillin-resistant coagulase-negative staphylococci were those to vancomycin (0.4%), nitrofurantoin (2%), doxycycline (20%) and amikacin (20%). Coagulase-negative staphylococci from cerebrospinal fluid, blood and skin were less often resistant to quinolones than isolates from respiratory tract, faeces and urine. A significant increase in resistance of coagulase-negative staphylococci to methicillin, erythromycin, gentamicin and ciprofloxacin was observed in the investigated period but the resistance to doxycycline and co-trimoxazole decreased in the last few years. To confirm the determination of methicillin resistance and coagulase production, a PCR method was developed which detects both the mecA and the coagulase gene. The results of the PCR method correlated well with the methicillin MIC as determined by an agar-dilution method.

Comparison of fluorescent BACTEC 9000 MB system, Septi-Chek AFB system, and Lowenstein-Jensen medium for detection of mycobacteria.

The newly developed fluorescent BACTEC 9000 MB system for automated culture of mycobacteria was compared with the Septi-Chek AFB system and Lowenstein-Jensen medium (LJ). A total of 2,005 clinical specimens were included in the study. Mycobacteria were isolated from 202 (10.1%) specimens, including 155 Mycobacterium tuberculosis complex isolates and 47 Mycobacteria other than M. tuberculosis isolates. Of 131 isolates detected by the BACTEC system, the Septi-Chek AFB system, or both, 120 (91.6%) were detected by the BACTEC system and 105 (80.2%) were detected by the Septi-Chek AFB system (P < 0.02). The recovery rate in the BACTEC system compared with that in the Septi-Chek AFB system was significantly higher for M. tuberculosis complex isolates (P < 0.005) and for isolates from acid-fast smear-negative specimens (P < 0.01). Of 148 isolates detected by the BACTEC system, LJ, or both, 142 (95.9%) were detected by the BACTEC system and 118 (79.9%) were detected by LJ (P < 0.001). The recovery rate in the BACTEC system compared with that on LJ was significantly higher for M. tuberculosis complex isolates (P < 0.001). The BACTEC system detected more mycobacteria from both smear-positive and smear-negative specimens than LJ. The mean times to detection of mycobacteria were 17.6 days for the BACTEC system, 26.0 days for the Septi-Chek AFB system, and 29.4 days for LJ. The BACTEC fluorescent 9000 MB system is a rapid, sensitive, and efficient method for the isolation of mycobacteria.

Surveillance of wound infections and a new theatre: unexpected lack of improvement.

In a new hospital, an operating theatre was designed, according to the best principles of infection control. An infection control nurse compared postoperative wound infection (PWI) rates before and after moving to the new site. PWI rates in clean general surgery were 28/1909 (1.5%) and 35/ 1891 (1.9%) before and after moving; in clean orthopaedic surgery they were 10/861 (1.2%) and 13/826 (1.6%). In patients undergoing joint replacement, followed up for one year, deep infections occurred in one out of 223 (0.4%) protheses in the old hospital and in one out of 252 (0.4%) in the new. These differences were not significant. We discuss whether the effects of the improvements were either too small (sterilization, clean-airflow) or insufficiently substantiated to be detectable in the period available. Such measures were directed against exogenous infections, which are rare compared with endogenous infections and have little influence on PWI-rates. Careful analysis of the results of existing surveillance data before designing new operating theatres are recommended.

In vitro activity of loracarbef against common respiratory pathogens compared with amoxicillin-clavulanic acid: a multi-centre study in The Netherlands.

Loracarbef (LC) is the first clinically available carbacephem. In order to evaluate the antimicrobial activity of LC, a total of 593 clinical strains of H. influenzae, M. catarrhalis, S. pneumoniae and S. pyogenes were collected by seven participating study centres. Minimal inhibitory concentrations for loracarbef and amoxycillin-clavulanic acid combination (AC) were determined by a microdilution method. The MIC-90 of beta-lactamase-negative strains of H. influenzae was 2.0 (LC) and 0.5 (AC), and for beta-lactamase-positive strains 4.0 (LC) and 2.0 (AC) mg/l. For beta-lactamase-negative and beta-lactamase-positive strains of M. catarrhalis, the MIC-90 results were 0.5 and 2.0 (LC) and 0.13 and 0.5 (AC) mg/l. The MIC-90 for AC was

[A rare cause of hemiparesis: cerebral hydatidosis]. / Een zeldzame oorzaak van hemiparese: cerebrale hydatidose.

A 6-year-old Turkish boy was brought to the Netherlands by his immigrant father because of hemiparesis. There were no signs of raised intracranial pressure. Cerebral hydatidosis was diagnosed. After surgical removal of the hydatid cyst and postoperative treatment with albendazole the patient recovered. Cerebral hydatidosis is very rare in the Netherlands but should be considered in immigrants from endemic countries.

Wound infection after arterial surgical procedures.

During the period October 1983 to March 1987, 603 patients who underwent arterial surgical procedures were studied to determine the incidence and treatment of wound infections. Bypass procedures were performed in 395 patients (65.5%), in which autogenous vein was used for 158 grafts (26%), synthetic Dacron for 216 grafts (36%), and umbilical vein for 21 grafts (3.5%). Thrombo-endarterectomies, embolectomies and patch-grafts were performed in 208 patients (34.5%). An Infection Control Nurse examined and registered the wounds. The definition of wound infection used in our study is equivalent to Szilagyi grade II infection. Vascular surgery is classified as clean surgery, the clean wound infection rate being a useful measurement to evaluate preventative measures and surgical technique. Thirty-one patients (5.1%) developed a wound infection as a postoperative complication. The overall incidence of wound complications including haematoma and seroma following arterial reconstruction was 13%. The site of wound infection was predominantly the groin. The most common pathogen was Staphylococcus aureus which was found in 17 patients (2.8%). All infections resolved without further surgical intervention. The influence of possible aetiological factors is considered and the importance of prophylactic antibiotics and good surgical technique is stressed.

Prevention of catheter-associated gram-negative bacilluria with norfloxacin by selective decontamination of the bowel and high urinary concentration.

Oral norfloxacin prevented Gram-negative bacilluria in female patients with hip fractures, who needed medium-term transurethral catheterization. This was shown in a placebo-controlled double-blind study of 34 patients. Seventeen of these received a suspension containing 200 mg norfloxacin and 500 mg amphotericin B, twice daily. In the placebo group, six cases of Gram-negative bacilluria had occurred by day 7, as compared with no cases during a median time of catheterization of 23 days in the group on medication. Bacteriuria, either by Gram-positive cocci or by Gram-negative bacilli, was observed in 50% of patients on placebo by day 7; in the treatment group this was the case by day 17 (P less than 0.001). Subsequent bacteriuria with Gram-positive cocci was eliminated by nitrofurantoin (50 mg qid) within four days. Norfloxacin is very suitable for the prevention of Gram-negative bacilluria, because it decontaminates Gram-negative bacilli from the bowel, reaches high concentrations in urine and rarely produces resistant variants.

Influence of cefaclor, phenethicillin, co-trimoxazole and doxycycline on colonization resistance in healthy volunteers.

The influence of oral administration of cefaclor, phenethicillin, co-trimoxazole and doxycycline on colonization resistance (CR) of the oropharynx and colon in healthy volunteers was studied. Antimicrobial agents were administered in a randomized cross-over design. No effect on CR of the oropharynx could be demonstrated. Phenethicillin decreased CR of the colon against Enterobacteriaceae (P = 0.001). Co-trimoxazole significantly decreased the concentration of Enterobacteriaceae in faeces (P = 0.03) but the decrease caused by cefaclor and doxycycline did not reach statistical significance. Administration of antimicrobial agents increased the appearance of secondary colonization by Enterobacteriaceae in faeces, especially when Escherichia coli was eliminated. During administration of phenethicillin, secondary colonization occurred at a concentration exceeding 10(7)/g in some volunteers. Following administration of cefaclor, co-trimoxazole and doxycycline, elimination of E. coli may result in the substitution by resistant Gram-negative bacilli in low concentrations.

Influence of amoxycillin, erythromycin and roxithromycin on colonization resistance and on appearance of secondary colonization in healthy volunteers.

We investigated the influence of oral administration of amoxycillin, erythromycin and roxithromycin on colonization resistance in healthy volunteers. Antibiotics were administered in a randomized cross-over design. No effect on the colonization resistance of the oropharynx could be demonstrated. Amoxycillin decreased the colonization resistance of the bowel against Enterobacteriaceae and yeasts, whose median concentration in faeces increased 100-fold and 30-fold respectively. Roxithromycin and erythromycin decreased the concentration of Enterobacteriaceae in faeces. Secondary colonization with Enterobacteriaceae was detected as often following roxithromycin as following amoxycillin, but the level of colonization with these bacteria was much higher following amoxycillin. Following roxithromycin and erythromycin the level of secondary colonization did not exceed the original concentration of Enterobacteriaceae, showing that these antibiotics did not decrease the colonization resistance against Enterobacteriaceae. The appearance of secondary colonization in faeces at levels equal to or lower than the concentration of Enterobacteriaceae before administration of antibiotics, should not be regarded as proof of disturbance of colonization resistance.

Enoxacin in lower respiratory tract infections.

In this open, non-comparative study 45 lower respiratory tract infections were treated with the new 4-quinolone, enoxacin. Special attention was paid to infections caused by Pseudomonas aeruginosa. Pseudomonas infections were treated with 600 mg bd. whereas infections caused by other bacteria were treated with 400 mg enoxacin bd. In 43 cases efficacy could be assessed. In six out of 23 cases Pseudomonas spp. were eradicated from the sputum. In 12 of the remaining 17 cases a clear reduction in bacterial numbers and a decrease of sputum volume and purulence were obtained. Clinical improvement or cure was obtained in 20 out of the 23 cases. Most of the causative microorganisms in the other infections were eradicated. In two patients Staphylococcus aureus persisted. Overgrowth with streptococci occurred in three patients. Adverse reactions were frequent and occurred in 29 out of 45 treatment periods. They were mainly related to the gastrointestinal tract and the central nervous system. In 25 out of 30 patients on concomitant treatment with theophylline an elevation of plasma theophylline concentrations occurred. Twelve of these patients developed signs and symptoms possibly related to theophylline toxicity. After treatment with enoxacin the MICs of most persisting Pseudomonas strains were two to four times higher than pre-treatment values.

Use of the enzyme-linked immunosorbent assay for the early diagnosis of Mycoplasma pneumoniae infection.

IgM and IgG antibodies to Mycoplasma pneumoniae were measured in 147 sera from four groups of patients by means of an indirect enzyme-linked immunosorbent assay (ELISA) and the results compared with those obtained by other methods. A good correlation was demonstrated between the complement fixation test and ELISA-IgM and to a lesser extent ELISA-IgG; for the metabolic inhibition test the reverse was the case. The indirect haemagglutination test appeared to detect mainly IgM antibodies. Low levels of IgM antibodies were detected by ELISA in 60 sera of children not suffering from pneumonia. However, if only high titres (greater than 800) were regarded as indicative of Mycoplasma pneumoniae infection, a presumptive diagnosis could have been made in 42 of 73 single acute phase sera from patients. Comparable results were obtained with IHA. The diagnostic level of IgM antibodies. was reached during the second week of the disease. It is concluded that examination of a single serum sample by either ELISA-IgM or IHA may assist in early diagnosis of Mycoplasma pneumoniae infection.