Rapid immunodiagnosis of streptococci and enterococci in blood cultures.

We evaluated a procedure for rapid identification of blood culture isolates of pneumococci, enterococci and beta-haemolytic streptococci groups A, B, C, and G. Immunological tests were applied directly to blood culture medium and included a quellung reaction for pneumococci, and latex agglutination tests (LAT) for pneumococcal antigen and Lancefield antigens A, B, C, D and G. During a one-year trial period with approximately 12,000 blood culture sets (BacT/Alert, Organon-Teknika), 208 sets showed pure growth of gram-positive cocci in pairs or chains by direct microscopy. Overall, a correct diagnosis was noted for 103 (63.2%, 95% CI: 55.3-70.6%) of 163 sets yielding pneumococci, beta-haemolytic streptococci, or enterococci. A procedure excluding Lancefield antigens only A, B, and D was implemented during a one-year follow-up period. With this simplified procedure positive and negative predictive values, respectively, were 1.00 and 0.87 for pneumococci, 1.00 and 0.94 for beta-haemolytic streptococci group A, 0.60 and 1.00 for beta-haemolytic streptococci group B, and 0.91 and 0.88 for enterococci. We conclude that rapid identification of gram-positive cocci is feasible and may improve the information given to clinicians at the first notification of positive blood cultures.

[Nosocomial infections with penicillin-resistant Streptococcus pneumoniae. Four clusters with pneumococci serotype 9V]. / Nosokomielle infektioner med penicillinresistent Streptococcus pneumoniae. Fire ophobninger med pneumokokker serotype 9V.

INTRODUCTION: The objective was to alert Danish hospital physicians to the risk of nosocomial spread of penicillin-resistant Streptococcus pneumoniae (PRP). MATERIALS AND METHODS: The study was conducted in the County of Northern Jutland during the 3-year period 1996-1998. Data on isolates of PRP were retrieved retrospectively from a computerised laboratory information system, and additional information was obtained from patients' charts and notes by infection control nurses. RESULTS: Four incidents of likely nosocomial spread of PRP, serotype 9V, were identified in departments of medicine or pulmonary diseases. Clusters included two to four patients. The eleven patients were 53 to 92 years of age, and all but one had severe underlying pulmonary disease or a malignant disorder. During the same period, we found that among pneumococcal bacteraemias of definite origin 8.9% (95% confidence limits 5.9-12.9%) was nosocomial. CONCLUSION: The risk of nosocomial spread of pneumococci, including PRP, should be acknowledged. A policy of isolation should be implemented for patients with PRP; isolation precautions should also be considered for patients with a previous isolate of PRP if readmitted, as such patients may become chronic carriers.

Ribotyping of strains of Moraxella (Branhamella) catarrhalis cultured from the nasopharynx and middle ear of children with otitis media.

Moraxella (Branhaomella) catarrhalis is frequently present in the nasopharyngeal microflora of small children, especially during episodes of acute otitis media . By means of ribotyping (restriction endonuclease analysis of chromosomal DNA combined with rRNA probing), we studied the genetic heterogeneity of 78 cultures of M. catarrhalis obtained from different localities in the nasopharynx of nine young children with secretory otitis media. Using HindIII and PstI as endonucleases, five different ribotypes were recognized, representing at least five different genotypes of M. catarrhalis. The distribution of these types was found to be almost identical to the distribution among 16 M. catarrhalis strains cultured from middle ear exudates of 16 children with acute otitis media. Ribotype HAPA was found in two-thirds of all the cultures investigated, and 44% of the children harboured more than one ribotype in the nasopharynx at the same time. The vast majority of the nasopharyngeal M. catarrhalis cultures were beta-lactamase positive. One child had both a HAPA ribotype, beta-lactamase-negative strain in the nasopharyngeal secretions, and HAPA ribotype, beta-lactamase-positive strains at the entrance of the eustachian tube, the nasopharyngeal tonsils, the folds of the nasopharyngeal tonsils and the oropharynx. All except one of the M. catarrhalis strains cultured from middle ear exudates were beta-lactamase positive.

Aminoglycoside resistance mechanisms in Enterobacteriaceae and Pseudomonas spp. from two Danish hospitals: correlation with type of aminoglycoside used.

Sixty-two aminoglycoside-resistant Gram-negative enteric bacteria were isolated over a 3-year period from two hospitals (Bispebjerg and Esbjerg) among a total of almost 270,000 isolates. These hospitals were selected because of their different aminoglycoside policies during the years investigated. At Bispebjerg Hospital the principal aminoglycoside used was tobramycin, while gentamicin was the first choice at Esbjerg Hospital. Escherichia coli was the most frequently found aminoglycoside-resistant species. Among the 61 aminoglycoside-resistant strains studied, resistance was due to aminoglycoside-modifying enzymes in all except two Xanthomonas maltophilia strains. The ANT(2") enzyme occurred significantly more often at Esbjerg Hospital (p = 0.001), while enzymes of the AAC(3) or AAC(6') moieties were more common, but not significantly so, at Bispebjerg Hospital. The phenotypic pattern of aminoglycoside resistance, as determined by disc diffusion, correlated 100% with the ANT(2") and AAC(3)-V (the two most common enzymes among the isolates) genotype of the organisms as established using DNA probes. Median minimum inhibitory concentrations (MICs) (mg/l) for clinically utilized aminoglycosides were: amikacin (1.6), gentamicin (25.0), kanamycin (50.0), netilmicin (1.6-25.0) and tobramycin (12.5-50.0). Isolates from Bispebjerg Hospital revealed significantly higher MICs for netilmicin and tobramycin (p < 0.01) as compared to isolates from Esbjerg Hospital.

Coagulase-negative Staphylococci in Danish blood cultures: species distribution and antibiotic susceptibility.

The distribution and antibiotic susceptibility of coagulase-negative staphylococci (CoNS) isolated from blood cultures was examined in samples from hospitals covering most of Denmark. A total of 499 CoNS isolates were detected in 477 blood cultures from 340 patients and speciated as Staphylococcus epidermidis, 285; Staphylococcus hominis, 61; Staphylococcus haemolyticus, 43; Staphylococcus warneri, 12; Staphylococcus cohnii, 7; Staphylococcus saprophyticus, 4; Staphylococcus capitis, 2 and Staphylococcus lugdunensis, 1. Seventy-eight isolates could not be identified to species level and six were Micrococcus spp. In 108 (22.6%) blood culture sets, more than one CoNS strain were found, as detected by species identification, antibiogram and biotyping. Significantly more blood cultures from patients in university hospitals were drawn from central venous catheters. Comparing university and non-university hospitals, the overall antibiotic susceptibility among CoNS was only slightly different, except for methicillin and amikacin. The prevalence of methicillin-resistant strains was 35.1% in the university hospital strains vs. 25.3% in the non-university hospital strains. The overall prevalence of methicillin resistance was 32%. Great geographic variation in both species distribution and antibiotic resistance was observed. The high prevalence of S. epidermidis makes subtyping of this species important.

The impact of the first notification of positive blood cultures on antibiotic therapy. A one-year survey.

The impact on antibiotic therapy of the first notification of positive blood cultures was assessed for 735 episodes of bacteraemia detected during 1992 in the County of Northern Jutland, Denmark. A primary focus of infection was defined in 498 episodes, the urinary tract being the most frequent (n = 182, 25%). Twenty-nine patients (3.5%) had died prior to the initial contact. In 12 episodes antibiotic therapy had either been stopped or data were not available, leaving 694 episodes for further assessment. In 567 episodes antibiotic therapy had been started prior to the initial contact, the most frequent regimen being ampicillin or an ampicillin-aminoglycoside combination (295 episodes), whereas cephalosporins, thienamycin, and fluoroquinolones were seldom used (41 episodes). The ongoing antibiotic coverage was deemed appropriate in 418 episodes (60%), non-optimal in 90 (13%), and lacking in 186 (27%). The notification of positive blood cultures elicited changes in antibiotic therapy in 315 episodes (45%), including commencement of antibiotic therapy in 127 (18%). Thus, blood culture results have a measurable impact on antibiotic therapy.

[Resistant gram-negative bacteria at seven intensive care units in Denmark]. / Resistente gramnegative bakterier på syv intensivafdelinger i Danmark.

A prospective study on the prevalence of resistance to 16 antibiotics in 704 Gram-negative bacteria isolated from seven intensive care units was undertaken in 1990. A microtitre panel carrying 16 antibiotics was used for susceptibility testing. The study revealed minor differences in resistance between the participating centres. The overall resistance was relatively low in Denmark, but there was increased resistance among E. coli from intensive care units compared to E. coli isolates from bloodcultures collected in 1988. At one centre the susceptibility of P. aeruginosa to gentamicin was slightly lower than at other centres, indicating a minor outbreak during the collection period. P. aeruginosa and Enterobacteriaceae with inducible production of beta-lactamases showed cross-resistance between penicillins and cephalosporins, but not between penicillin/cephalosporins and imipenem gentamicin or ciprofloxacin. The resistance among the repeated isolates of inducible Enterobacteriaceae was slightly higher than among the initial isolates indicating acquisition of resistance or selection of resistant mutants.

[Ampicillin-resistant Haemophilus influenzae. Prevalence in isolates from Danish children]. / Ampicillinresistente Haemophilus influenzae. Forekomst i isolater fra danske børn.

The prevalence of ampicillin-resistance was assessed among a total of 2766 strains of H. influenzae isolated from lower respiratory tract secretions, middle ear secretions, spinal fluid specimens, and blood cultures from children 0-15 years of age tested in two separate counties in Denmark during the period from 1986 to May, 1993. All strains were tested for susceptibility to ampicillin with disc or tablet diffusion technique and strains were examined for beta-lactamase production with a chromogenic cephalosporinase test. In the county of Northern Jutland the rate of beta-lactamase production in non-encapsulated H. influenzae was 2.5% in 1986 rising to 9.3% in 1993. The rate of beta-lactamase production in H. influenzae type b was 4.1% without any rise. In the county of Copenhagen the rate of beta-lactamase production in non-encapsulated H. influenzae rose from 6.3% in 1986 to 10.6% in 1992. In 1993 a further increase to 20.7% was noticed. This year the number of specimens sent to the laboratory and the number of H. influenzae isolated were lower compared to previous years. Thus a different selection of patients may explain the increase in the rate of beta-lactamase production in 1993. The rate of beta-lactamase production in H. influenzae type b was 8.5%. No strains were resistant to ampicillin in diffusion test other than the beta-lactamase producers.

[Pseudomonas bacteremia developing after whirlpool bath]. / Pseudomonas-bakteriaemi opstået efter anvendelse af Spa-bad.

Whirlpools may be responsible for transmission of microbial infections among the bathers if the technical hygienic conditions in the care of the bath are not observed. Two cases of infection with Pneudomonas bacteria were observed after use of whirlpools in a deluxe summer chalet. On the basis of the documented cases, the necessity for specific requirements concerning the installation, running and control of whirlpools used commercially should be considered. In their advisory brochures, the responsible authorities should ensure that the requirements made concerning whirlpools should be intensified so that these baths in summer chalets which are rented out should be subject to public control. Owners and users of whirlpools should be aware of the importance of meticulous hygiene in their care.

[Prosthetic valve endocarditis caused by Haemophilus parainfluenzae]. / Klapprotese-endocarditis forårsaget af Haemophilus parainfluenzae.

A case of endocarditis preceded by dental treatment without prophylactic antibiotics and caused by Haemophilus parainfluenzae in a patient with a biological heart valve prosthesis is described. This bacteria grows slowly in the usual blood culture media and, because of this, the etiological diagnosis was not established until after incubation for 11 days. Blood cultures from patients suspected of having endocarditis should be incubated for longer than the usual five to seven days. Close cooperation between the clinical microbiologist and clinicians is necessary so that important findings are not overlooked. Dental treatment of patients with heart valve prostheses should always take place under antibiotic prophylaxis.

Imported pedal chancroid: case report.

A man aged 22 who had returned from the Fiji Islands to Denmark had chancroid on the left foot, but no history or sign of primary genital infection. The pedal location only is an unusual presentation of the disease, which was diagnosed only microbiologically. Chronic tropical ulcers therefore demand special microbiological attention.

The clinical significance of the genital microbiologic flora at vacuum aspiration following miscarriage.

85 women undergoing vacuum aspiration following miscarriage were studied. At the time of vacuum aspiration, immunofluorescent stainings for detection of C. trachomatis proved positive in 5.9% of the patients. Group B streptococci were isolated in 7.5%, coliforms in 3.5%, and Gardnerella vaginalis in 51% of the patients. The overall frequency of postabortal pelvic inflammatory disease (PID) was 3.5%, whereas 40% of chlamydia-positive women contracted postabortal PID (p less than 0.05). No significant relation between other microorganisms and postabortal PID was observed. The duration of postabortal bleeding was unrelated to the genital microbiologic flora. Based on anamnestic information about previous pregnancies and duration of preoperative bleeding it was possible to define subgroups at risk of harboring C. trachomatis and coliforms. The clinical significance of this is unknown.

[Examination of young women with recurrent symptoms of cystitis]. / Undersøgelse af yngre kvinder med recidiverende cystitsymptomer.

Fifty women with recurrent symptoms of cystitis (urgent onset of painful and frequent voiding) were extensively examined bacteriologically. All were submitted to intravenous urography, cystoscopy, gynaecological and urodynamic examination and the urine was examined cytologically and by culture. A control group of 10 healthy women were submitted to the same bacteriologic examinations. Only in a few cases did the investigations give an explanation of the condition but, generally, the examination programme did not contribute to the etiology. Chlamydia trachomatis was found in 6%, which was comparable to the normal population. Gardnerella vaginalis must be considered as part of the normal flora. The extensive examination programme cannot be recommended as a routine.

Contamination of intravenous infusion systems--the effect of changing administration sets.

Intravenous administration sets were changed at varying time intervals between every 24 h and 120 h in 387 patients. The rates of intraluminal contamination of the cannulae and of local inflammation were measured in relation to the time interval between changing sets. There was no correlation between phlebitis and intraluminal contamination, but a significant association was found between phlebitis and fever, infusion of potassium at greater than 10 mmol l-1, Venflon type 140 and infusion of blood or intralipid. No correlation was found between septicaemia and intraluminal contamination of the infusion systems. Contamination of cannulae increased slightly with time, but this was not statistically significant. We conclude that there will be no clinical benefit by daily changing of administration sets, compared with changing up to every fifth day.

Susceptibility testing with disc diffusion for new cephalosporins: pre-diffusion revisited.

The purpose of the present study was to investigate the effect of 20-hour pre-diffusion, i.e. placing the antibiotic-containing discs on the agar for 20 hours prior to inoculation, as compared to direct diffusion, i.e. placing the discs on the agar immediately after inoculation, for the newer 3. generation cephalosporins as represented by ceftazidime and ceftriaxone. Regression lines (zone sizes vs. inhibitory concentrations, as measured by plate-dilution) were constructed for three groups of bacteria chosen because of their differences in growth characteristics on agar: E. coli (n = 50), Enterobacter sp. (n = 35), and streptococci (n = 51). The results for both cephalosporins were: 20-hour pre-diffusion produced larger zones than direct diffusion, regression studies for 20-hour pre-diffusion as compared to direct diffusion resulted in greater variation in zone sizes, numerically lower slopes, lower residual variances and higher correlation coefficients, and regression lines were significantly different for the 3 groups of bacteria with direct diffusion but not so with 20-hour pre-diffusion. Considering the interpretation of zone sizes with disc diffusion for the cephalosporins tested, 20-hour pre-diffusion was superior to direct diffusion.

Meningitis and brain abscess due to Haemophilus paraphrophilus.

A case of meningitis and brain abscess due to Haemophilus paraphrophilus in a patient with congenital heart disease is reported. The abscess communicated with the cerebral ventricular system. Although the infecting strain was found to be highly sensitive to ampicillin, the patient died despite appropriate antimicrobial therapy. Characteristics distinguishing Haemophilus paraphrophilus and related species are discussed.

Antibacterial activity in vitro and regression studies for ceftazidime and ceftriaxone.

The antibacterial activity in vitro of ceftazidime and ceftriaxone was investigated against 575 recent clinical isolates. Both cephalosporins displayed excellent activity against most of the pathogens tested, in particular Gram-negative bacteria, including Pseudomonas aeruginosa. Apart from the Pseudomonas group, Acinetobacter calcoaceticus and Campylobacter jejuni ceftriaxone was slightly to moderately more active than ceftazidime overall. Ceftriaxone was moderately active against Streptococcus faecalis. Regression lines for the two antibiotics were almost identical. Corresponding to differences in susceptibility, the zone sizes differed for the two drugs with respect to certain bacterial groups, e.g. Pseudomonas sp. and enterococci. Therefore, the two cephalosporins cannot substitute for each other in disc susceptibility testing. Breakpoints for disc tests around 8-16 micrograms/ml, as suggested in the literature, appear too high considering the beneficial pharmacokinetic properties of the two drugs.