Antimicrobial susceptibility of bacterial isolates in south Sweden including a 13-year follow-up study of some respiratory tract pathogens

Molecular serotyping and genotyping of penicillin non-susceptible pneumococci: the introduction of new sequence types, Tehran, Iran

The emergence of penicillin non-susceptible Streptococcus pneumoniae (PNSP) isolates can pose significant challenges to today's health-care system. Resistant clonal isolates are disseminated in different regions and countries, and this study was focused on the description of the epidemiological spread of these strains. Clinical samples were collected from individuals admitted to hospitals affiliated to the Tehran University of Medical Sciences, Iran. To investigate the molecular characteristics of PNSP isolates, they were subjected to molecular typing using multi-locus sequence typing (MLST). Serotype distributions of S. pneumoniae isolates were also evaluated by multiplex PCR assay. The most prevalent serotypes in the PNSP isolates were 23F, 19F, 14, 3 and 9V. Two isolates were considered as a non-vaccine serotype. The MLST analysis showed that PNSP isolates belonged to five different clonal complexes (CC180, CC217, CC81, CC63 and CC320) and 42% (5/12) of the sequence types were novel (12936, 12937, 12938, 12939 and 12940). This study indicates the high level of heterogeneity that is present among PNSP isolates. Unexpected high genetic diversity in small populations indicates consecutive diversification of resistant strains.

Children with respiratory tract infections in Swedish primary care; prevalence of antibiotic resistance in common respiratory tract pathogens and relation to antibiotic consumption

BACKGROUND

The majority of antibiotics consumed in developed countries are prescribed in primary care. However, little is known about resistance levels in the primary care population.

METHOD

Nasopharyngeal cultures were obtained from children, 0-10 years of age, seeking care at their Primary Health Care Centre with symptoms of respiratory tract infection. Parental questionnaires were used to retrieve information about the child's previous antibiotic consumption.

RESULT

Cultures from 340 children were gathered. The level of resistant Haemophilus influenzae was low and the prevalence of penicillin non-susceptible pneumococci (PNSP MIC ≥ 0.125 mg/L) was 6% compared to 10% (p = 0.31) in corresponding cultures from children diagnosed at the local clinical microbiology laboratory. Antibiotic treatment within the previous 4 weeks predisposed for resistant bacteria in the nasopharynx, OR: 3.08, CI 95% (1.13-8.42).

CONCLUSION

Low prevalence of PNSP supports the use of phenoxymethylpenicillin as empirical treatment for childhood upper respiratory tract infections attending primary care in our setting. It is important that studies on resistance are performed in primary care populations to evaluate data from microbiological laboratories. Recent antibiotic treatment increases risk of bacterial resistance in children and continuous work to reduce unnecessary antibiotic prescribing should be prioritised.

Prevalence of penicillin-non-susceptible Streptococcus pneumoniae in children in day-care centres subjected to an intervention to prevent dispersion

BACKGROUND

The aim of this study was to evaluate the day-care interventions implemented in southern Sweden to restrict the dispersion of penicillin-non-susceptible pneumococci with a minimum inhibitory concentration of penicillin G of at least 0.5 mg/l (PNSP0.5).

METHODS

A retrospective epidemiological study was performed and data from 109 day-care centre interventions from 2000 to 2010 were analysed, including screening results from 7157 individuals.

RESULTS

It was found that 42% of the children were carriers of pneumococci and 5% of the screened children were PNSP0.5 carriers. Very few personnel were PNSP0.5 carriers and they were carriers for only a short time. Significantly more contact cases with the same serogroup as the index case were found in the first screening and in the same department as the index case, but a substantial number of contact cases were found in adjacent departments.

CONCLUSIONS

Screening of personnel is not worth the effort. Based on our results, procedures to restrict dispersion of PNSP0.5 in day-care centres could be improved. To find the majority of contact cases with PNSP0.5 an early screening including adjacent departments seems to be the best approach.

Community-acquired bacteremia and acute cholecystitis due to Enterobacter cloacae: a case report

Introduction

Enterobacter cloacae is responsible for 65-75% of all Enterobacter infections, bacteremia being the most common syndrome. The majority of infections are nosocomially acquired and in patients with predisposing factors.

Case presentation

We present a case of E. cloacae bacteremia secondary to acute cholecystitis in a 60-year-old man with recent diagnosis of cholelithiasis. The diagnosis was established with abdominal echography and positive blood and biliary cultures. The patient was managed successfully with cholecystectomy and antibiotic therapy.

Conclusion

The peculiarity of our case is the development of community-acquired bacteremia due to E. cloacae with a clear infectious focus, as a single agent isolated in several blood cultures, in a patient without severe underlying diseases, prior antimicrobial use or previous hospital admission. Although the majority of Enterobacter spp. infections are nosocomially acquired, primary bacteremia being the most common syndrome, these pathogens may also be responsible for community-acquired cases. Patients without predisposing factors may also be affected.

A 10-year follow-up study of penicillin-non-susceptible S. pneumoniae during an intervention programme in Malmö, Sweden

Changes in the proportion of penicillin-non-susceptible Streptococcus pneumoniae (PNSP) isolates during an intervention programme were evaluated by phenotypic analysis of all initial isolates with penicillin MIC > or =0.5 microg/ml (n=1248) collected 1995-2004. During the study period, the proportion of such isolates was fairly constant (12-19%), and there was no statistically significant variation in the proportion of total PNSP cases (MIC > or =0.12 microg/ml) or PNSP with MIC > or =0.5 microg/ml, with the exception of an increase in 2004. Analysis restricted to clinical cases revealed no statistically significant changes. 23 different serogroups were found, and serogroup 9 isolates accounted for almost half of the PNSP cases. Only minor changes in phenotypic characteristics occurred in the other serogroups, which indicates that the increase in PNSP in 2004 was not due to import of a new resistant clone. Antibiotic consumption is considered to be an important risk factor for penicillin resistance in S. pneumoniae. After initiation of the intervention programme in Malmö, overall prescribing of antibiotics decreased 28%, and the reduction was even greater among children (52%). In conclusion, the proportion of PNSP isolates in Malmö has remained stable, despite the intervention programme and decreased consumption of antibiotics.

Modeling pneumococcal resistance to penicillin in southern Sweden using artificial neural networks

In recent decades, penicillin-resistant pneumococci (PRP) have emerged and spread rapidly between and within countries over the world. In this study we developed an iterative artificial neural network (ANN) model to describe and predict the spread of PRP in space and time as a function of antibiotic consumption and a number of different confounders. Retrospective data from 1997 to 2000 on an international epidemic PRP clone (serotype 9V) and antibiotic consumption data from Southern Sweden were used to train the ANN models and data from 2001 to 2003 for evaluation of the model predictions. Five different ANN models were trained, each with independent topology optimization for alternative sets of input variables to find the most descriptive model. The model containing all variables was the only one performing better than the reference linear models, as assessed by the correlation between predictions and observations. The inability to identify a smaller subset of most predictive parameters may reflect either diffuse causal mechanisms or just the absence of critical experimental indicators from the dataset. The iterative ANN model identified is useful to predict future data. The sensitivity analysis of the model suggests that past incidence has a small effect on the number of PRP cases.

Penicillin-Resistant Pneumococci in Sweden 1997–2003: Increased Multiresistance Despite Stable Prevalence and Decreased Antibiotic Use

Antimicrobial resistance patterns and capsular groups of penicillin-resistant Streptococcus pneumoniae (PRP; MIC penicillin G > or = 0.5 mg/ml) in Sweden between 1997 and 2003 were described, and trends in resistance and antibiotic sales during the same period were compared. The most common serogroups were in descending order 9, 19, 14, 23, and 6. Despite a low and stable annual PRP rate (proportion of PRP out of all pneumococci) of around 2% during the study period, the proportion of PRP resistant to other antibiotics increased. Of all tested PRP isolates, 82% were also resistant to trimethoprim/sulfamethoxazole, 32% had additional resistance to tetracycline, and 26% to erythromycin. Antibiotic sales figures for all studied antibiotic subgroups decreased during the same period. Little correlation was found between antibiotic sales and PRP resistance rates, indicating that there are still other poorly defined factors contributing to the reported resistance levels in the population. However, although PRP strains in Sweden are becoming more commonly resistant to antibiotics other than beta-lactams, the low and further reduced antibiotic sales still might have delayed the development and rapid spread of PRP in the population.

Modelling the spread of penicillin-resistantStreptococcus pneumoniae in day-care and evaluation of intervention

In 1995, a disease control and intervention project was initiated in Malmöhus county in southern Sweden to limit the spread of penicillin-resistant pneumococci. Since most of the carriers of pneumococci are preschool children, and since most of the spread is believed to take place in day-care, a mathematical model, in the form of a stochastic process, for the spread in a day-care group was constructed. Effects of seasonal variation and size of the day-care group were particularly considered. The model was then used for comparing results from computer simulations without and with intervention. Results indicate that intervention is highly effective in day-care groups with more than ten children during the second half of the year.

Limited spread of penicillin-nonsusceptible pneumococci, Skåne County, Sweden

In response to increasing frequencies of penicillin-nonsusceptible pneumococci (PNSP), for which the MIC of penicillin was >0.12 mg/L, in Skåne County, southern Sweden, national recommendations were initiated in 1995 to limit the spread of pneumococci with high MICs (> or =0.5 mg/L) of penicillin (PRP), especially among children of preschool age. Traditional communicable disease control measures were combined with actions against inappropriate antimicrobial drug use. During the first 6 years that these recommendations were applied in Skåne County, the average frequency of penicillin-resistant pneumococci has been stable at =2.6%, as has the average PNSP frequency (7.4%). However, PNSP have been unevenly distributed in the county, with the highest frequencies in the southwest. Simultaneously, the rate of antimicrobial drug use for children <6 years of age was reduced by 20%. Thus the spread of PNSP between and within the municipalities in the county has been limited.

In vitro activity of gemifloxacin and contemporary oral antimicrobial agents against 27,247 Gram-positive and Gram-negative aerobic isolates: a global surveillance study

This study was a multi-centre, multi-country surveillance of 27247 Gram-positive and Gram-negative isolates collected from 131 study centres in 44 countries from 1997 to 2000. MICs of gemifloxacin were compared with penicillin, amoxicillin-clavulanic acid, cefuroxime, azithromycin, clarithromycin, trimethoprim-sulphamethoxazole, ciprofloxacin, grepafloxacin and levofloxacin by broth microdilution. Penicillin resistance in Streptococcus pneumoniae was extremely high in the Middle East (65.6%), Africa (64.0%) and Asia (60.4%) and lower in North America (40.3%), Europe (36.9%) and the South Pacific (31.8%). Macrolide resistance in S. pneumoniae was highest in Asia (51.7%) but varied widely between laboratories in Europe (26.0%), North America (21.6%), the Middle East (13.7%), the South Pacific (10.6%) and Africa (10.0%). All the study quinolones were highly active against penicillin-resistant and macrolide-resistant S. pneumoniae. Overall, gemifloxacin had the lowest MIC(90) at 0.06 mg/l with MICs 4-64-fold lower than ciprofloxacin, levofloxacin and grepafloxacin against S. pneumoniae. Gemifloxacin MICs were more potent than grepafloxacin > levoflaxacin > ciproflaxin against the Gram-positive aerobes and shared comparable Gram-negative activity with ciprofloxacin and levofloxacin.

Pathogens in acute otitis media--impact of intermittent penicillin V prophylaxis on infant nasopharyngeal flora

OBJECTIVE

To investigate whether intermittent short-term courses of penicillin V (PcV) administered as intermittent prophylaxis against acute otitis media (AOM) during upper respiratory tract infections altered the nasopharyngeal bacterial flora and/or its susceptibility to penicillin.

METHODS

In a double blind, placebo controlled study 70 children (30 in the PcV group and 40 in the placebo group) were followed for 1 year. At episodes of upper respiratory tract infection the children were given PcV or placebo and then seen by one of the investigators within 3 days. The tympanic membranes were examined by otomicroscopy and a culture from the nasopharynx was obtained. If AOM was found PcV was given (25 mg/kg bw b.i.d) for 5 days. If the child presented normal eardrums or signs of secretory otitis media (SOM) the study treatment was continued for a total of 5 days. All children were also examined bimonthly throughout the study irrespective of episodes of URTI or AOM.

RESULTS

No increase in the number of isolates of S. pneumoniae with reduced susceptibility to penicillin (MIC> or =0.125 mg/l) was noted in either group compared with the incidence in the population in Sweden at the time of the study (when ca. 10% of pneumococci had a reduced susceptibility to penicillin). The number of cultures positive for S. pneumoniae were statistically reduced in children during treatment with PcV compared with children receiving placebo, while the number of cultures positive for H. influenzae and M. catarrhalis were unaffected. No increase in the number of cultures positive for beta-lactamase producing H. influenzae was noted (ca. 10%).

CONCLUSION

Repetitive short term PcV courses during URTI in infants did not increase the number of cultures positive for S. pneumoniae with reduced susceptibility to penicillin or beta-lactamase producing H. influenzae.

Carriage of penicillin-resistant Streptococcus pneumoniae by children in day-care centers during an intervention program in Malmo, Sweden

BACKGROUND

An increasing incidence of penicillin-resistant Streptococcus pneumoniae (PRP) was detected in Malmo in 1994.

OBJECTIVE

To evaluate clonality and factors facilitating the spread of PRP among children in day-care centers (DCCs).

METHODS

We used phenotypic and DNA-fingerprinting methods in conjunction with epidemiologic data from the South Swedish Pneumococcal Intervention Project's investigation of 63 DCCs during a 3-year period (1995 to 1997) in the Malmo region.

RESULTS

A questionnaire about building and hygiene standards disclosed no statistically significant risk factor for carriage of pneumococci. However, age younger than the mean age at the DCC or in the child group was positively associated with carriage. Contrary to expectations no association with the number of children, either at the DCC or in the individual groups, was found. Of 2912 investigated children 1224 (42%) were carriers of S. pneumoniae, and 373 (12.8%) were PRP carriers (MIC > or = 0.1 microg/ml). Among isolates with MIC > or = 0.5 microg/ml 9 serogroups and 30 genetic types were found. Two clones in serogroups 9 (33%) and 19 (24%) were dominant in most municipality districts, and dominance was sustained during the whole study period. The previously internationally recognized serotype 9V clone seemed to be very stable, with a single DNA type and resistance pattern during the study period. In contrast the serogroup 19 isolates and other serogroups had diverse DNA types and resistance patterns, supporting the hypothesis that DCCs have a unique microenvironment facilitating the recombination of penicillin-binding protein genes among streptococci. In five DCCs we found PRP isolates with two different serogroups but an identical genetic type, indicating that serotype shift may be a common phenomenon in DCCs.

CONCLUSION

Multivariate logistic regression of risk factors disclosed that young age of the children in the child groups was a significant risk factor for carriage of S. pneumoniae.

Frequency of penicillin-resistant pneumococci in children is correlated to community utilization of antibiotics

OBJECTIVE

To study the impact of the utilization of antibiotics in children at the population level on the frequency of penicillin-nonsusceptible pneumococci (PNSP).

DESIGN

Children ages 0 to 6 years with a nasopharyngeal culture of PNSP were registered on place of residency in the 20 municipalities of the former Malmöhus County (since 1998 a part of Skåne County). Where possible the total number of nasopharyngeal cultures with growth of pneumococci was registered as well. All antibiotic prescriptions for 0- to 6-year-old children were analyzed in the 20 municipalities.

MAIN OUTCOME MEASURES

Correlation between the utilization of antibiotics and the frequency of PNSP in children at the municipality level.

RESULTS

The proportion of PNSP among all isolates of pneumococci from nasopharyngeal cultures varied between 0 and 49.5%. The antibiotic utilization in children varied among the 20 neighboring municipalities from 8.5 to 19.7 defined daily doses per 1000 children per day. The municipalities with high total utilization also had more frequent use of macrolides and broad spectrum antibiotics. The was a significant correlation between antibiotic use and the proportion of PNSP (correlation coefficient, 0.96; P = 0.002), and the correlation coefficients for trimethoprim-sulfamethoxazole, amoxicillins, macrolides and cephalosporins were significant at the 0.001 level. There was no significant correlation between the use of penicillin V and the frequency of PNSP. CONCLUSIONS. There was a significant correlation between the frequency of PNSP and the utilization of antibiotics in children at the population level.

International study comparing cefdinir and cefuroxime axetil in the treatment of patients with acute exacerbation of chronic bronchitis

OBJECTIVES

To assess the efficacy and tolerability of three antibiotic regimens in patients with acute exacerbation of chronic bronchitis.

METHODS

In this double-blind, randomized, multicentered, parallel-group study, patients received once-daily cefdinir 600 mg, twice-daily cefdinir 300 mg, or twice-daily cefuroxime axetil 250 mg for 10 days. Primary efficacy measures were microbiologic eradication rate, by pathogen and by patient, and clinical response rate, by patient.

RESULTS

Of 1045 patients, 589 were evaluable for efficacy. At baseline, most patients had moderate or severe cough and sputum production as well as rhonchi, wheezing, and dyspnea. The microbiologic eradication rates by pathogen were 90% with once-daily cefdinir, 85% with twice-daily cefdinir, and 88% with twice-daily cefuroxime. The corresponding values for microbiologic eradication rate by patient were 90% (once-daily cefdinir), 85% (twice-daily cefdinir), and 86% (twice-daily cefuroxime). The respective clinical response rates by patient were 81%, 74%, and 80%. There were no significant differences in the incidence of drug-related adverse events or discontinuations due to adverse events. Diarrhea was the most frequent complaint.

CONCLUSIONS

The results indicate that the efficacy and tolerability of cefdinir, once or twice daily, and cefuroxime were comparable with no significant differences between the regimens used.

Penicillin-resistant pneumococci in southern Sweden, 1993-1997

In Malmöhus County, Southern Sweden, the frequency of penicillin-resistant pneumococci in nasopharyngeal specimens of outpatients with respiratory tract infections increased from 3.1% in 1993 to 7.6% in 1995, and was thereafter rather stable. Over the period, 82-85% of the patients with penicillin-resistant strains were children 0-6 years of age. Ten groups/types constituted 96-100% of the penicillin-resistant isolates. Grouping/typing of 200 consecutive isolates in October and November each year indicated that the distribution of groups/types amongst patients with respiratory tract infections was rather constant over the period. The frequency of penicillin-resistant pneumococci of groups/types 6, 14, and 19 roughly corresponded to the occurrence of these groups/types amongst the consecutive isolates. Other groups/types 9, 15, 21, and 23 either showed a pronounced increase or decrease, which could not be related to the prevalence of these groups/types among the consecutive isolates or degree of antibiotic resistance. Penicillin-resistant group 9, introduced in the area in 1993, consisted of one single clone, 9V. The stabilized level of penicillin resistance since 1995 may be related to the preventive measures implemented in the area, including day-care interventions, and measures to reduce the prescription rate of antibiotics to outpatients with respiratory tract infections.

Limiting the spread of penicillin-resistant Streptococcus pneumoniae: experiences from the South Swedish Pneumococcal Intervention Project

In an attempt to limit the spread of penicillin-resistant pneumococci (PRP), an intervention project was initiated in the Malmöhus County, southern Sweden in January 1995. The ongoing project combines traditional communicable disease control measures and actions aiming at reducing antibiotics consumption. All patients in the county with a nasopharyngeal culture positive for PRP with MIC of Penicillin G > or =0.5 mg/L are followed with nasopharyngeal cultures until PRP-negative. Nasopharyngeal cultures are obtained from family members and close contacts of the index cases. Preschool children carrying PRP are denied attendance at group day-care. From January 1995 to March 1997, 1,038 PRP-carriers (429 index cases and 609 contact cases) were identified. Children aged 1-6 years dominated (83%). Antibiotics sales decreased during the study period, and epidemiologic data indicate that the intervention may have limited the dissemination of PRP in the county, but further evaluation is needed.

Several different clones present during the penetration phase of resistant Streptococcus pneumoniae in the city of Malmö, Sweden

A rapid increase in the prevalence of Streptococcus pneumoniae with reduced sensitivity to penicillin (MIC > or = 0.12 microgram/mL) was noted among clinical isolates during a 15-month period in 1994-1995 in the city of Malmö, Sweden. All first-time clinical isolates (n = 178) were consecutively collected and investigated for genetic relatedness with BOX-A PCR and arbitrarily primed (AP) PCR. An improved method for chromosomal DNA extraction and the use of three reliable discriminatory primers for AP-PCR of S. pneumoniae are described. Using molecular fingerprinting, 30 different genotypes were discerned among the 178 isolates. The majority (87%) of isolates belonged to serogroups 6, 9, 15, 19, and 23. Resistance patterns and serogrouping indicated the presence of at least three major phenotypic clones. DNA fingerprinting in conjunction with minimum inhibitory concentration (MIC) values, resistance patterns, and epidemiological data confirmed the existence of two clones belonging to serogroups 6 and 9. Of the 178 isolates, 82% were from children of preschool age, most of whom attended day-care centers. We conclude that abundant S. pneumoniae strains with MICs > or = 0.12 microgram/mL for penicillin were present in the city of Malmö during the study period. At least two genetically discrete clones causing clinical illness were identified, and attendance at day-care centers may be a major factor in the spread of these strains.

Introduction and clonal spread of penicillin- and trimethoprim/sulfamethoxazole-resistant Streptococcus pneumoniae, serotype 9V, in southern Sweden

As part of an intervention project, all patients in Malmöhus county with a culture positive for penicillin-resistant pneumococci, MIC > or =0.5 mg/L (PRP), have been registered since January 1995. Nasopharyngeal specimens were obtained from family members and close contacts of identified carriers. Children were denied attendance at regular day-care until PRP-negative. In 1995 and 1996, PRP were isolated from 882 individuals, 364 of whom had clinical infection and the remaining of whom were asymptomatic carriers. In 49%, the PRP were of serogroup 9, with MIC of penicillin 0.5-2.0 mg/L and resistance to trimethoprim/sulfamethoxazole. Further analyses with serotyping and genetic fingerprinting suggested strongly that most of the isolates belonged to a single serotype 9V clone. Month by month, an apparently continuous spread appeared from one municipality to a neighboring one. In most communities, the serotype 9V PRP appeared and disappeared within a few months. The active procedures of the intervention project may have limited the spread of the clone in the county.

Medical audit changes physicians' prescribing of antibiotics for respiratory tract infections

OBJECTIVE

To reduce the prescribing of antibiotics in respiratory tract infections (RTI).

DESIGN AND SUBJECTS

The Audit Odense model for registration and quality development was used for RTI. Twenty general practitioners registered their consultations for RTIs during 4 weeks in February-March (n = 1124) and November-December (n = 926) in 1995. Diagnosis, choice of antibiotics and diagnostic tools were registered. In between the two registrations an active intervention took place. Consultations for RTIs among 25 physicians (who had not participated in any intervention or follow-up discussion) served as a control.

SETTING

General practice in southern Sweden.

OUTCOME MEASURES

Prescribing of antibiotics before and after an intervention.

RESULTS

The proportion of patients not receiving an antibiotic increased from the first to the second registration in both groups, in the intervention group from 45 to 55% (p < 0.001) and in the control group from 36 to 40% (p = 0.0298). The reduction was most evident in patients diagnosed with tonsillitis and bronchitis. This was in concordance with an increase in the use of desktop diagnostics (Strep A and CRP).

CONCLUSION

These results indicate that it is possible to achieve a change in the utilisation of antibiotics in the treatment of RTIs and that the Audit Project Odense (APO) model could be a valuable tool.

Major change in the use of antibiotics following a national programme: Swedish Strategic Programme for the Rational Use of Antimicrobial Agents and Surveillance of Resistance (STRAMA)

In order to reduce inappropriate use of antibiotics and to counteract the increase in antimicrobial resistance in community-acquired and nosocomial infections, a national project was initiated in Sweden in 1994: the Swedish Strategic Programme for the Rational Use of Antimicrobial Agents and Surveillance of Resistance. In the first years the project focused on inappropriate prescribing of antibiotics to children with respiratory tract infections and on the surveillance of resistance in pneumococci. Statistics on antibiotic sales on a national and county level and for different age-groups were studied. Between 1993 and 1997 antibiotic prescribing was reduced by 22%, from 16.3 to 13.0 defined daily doses (DDD) per 1000 inhabitants/d. The reduction was most pronounced for children, 0-6-y-old, from 15.7 to 9.7 DDD/1000 children/d. Macrolides and amoxicillin/co-amoxyclav decreased most. There were large variations in antibiotic sales in different counties, and a decrease was also noted in counties starting from a low level. In the county with the highest sales in 1993, antibiotic prescribing to children was reduced by 40%. The national frequency of penicillin-non-susceptible pneumococci (MIC > or =0.1 mg/l) has not increased during the 1990s and the increasing incidence in southern Sweden seems to have been curtailed. During the period that the project has been running, a major change in the use of antibiotics, especially for pre-school children, has been achieved.

Antibiotic resistance in Streptococcus pneumoniae, Haemophilus influenzae and Streptococcus pyogenes in respiratory tract infections in outpatients

Sensitivity patterns of Streptococcus pneumoniae, Haemophilus influenzae and Streptococcus pyogenes were studied prospectively in an outpatient population seeking medical advice for respiratory tract infections (RTI) in the Southern parts of Stockholm. In total, 3,214 nasopharyngeal and 1,907 throat swabs were cultured during January-February 1996. 32% of the patients had received antibiotics during the previous year. Reduced penicillin sensitivity in S. pneumoniae was rare (1.3%) and only seen in patients treated with antibiotics during the previous 4 months. Beta-lactamase production in H. influenzae was found in 13.4% of patients who had been treated with antibiotics during the last 4 months and in 7.9% of the others. No resistance (< 1%) to erythromycin was seen in S. pyogenes. In this population-based surveillance, the levels of resistance in common respiratory tract pathogens were thus low and correlated to previous antibiotic treatment. Strict indications for antibiotic treatment in uncomplicated RTI are advocated to maintain a low resistance rate. Penicillin is still the drug of choice in patients without frequent recurrences of RTI in a setting similar to the one studied.

Moraxella catarrhalis: clinical significance, antimicrobial susceptibility and BRO beta-lactamases

Moraxella catarrhalis is an important pathogen of humans. It is a common cause of respiratory infections, particularly otitis media in children and lower respiratory tract infections in the elderly. Colonisation of the upper respiratory tract appears to be associated with infection in many cases, although this association is not well understood. Nosocomial transmission is being increasingly documented and the emergence of this organism as a cause of bacteremia is of concern. The widespread production of a beta-lactamase enzyme renders Moraxella catarrhalis resistant to the penicillins. Cephalosporins and beta-lactamase inhibitor combinations are effective for treatment of beta-lactamase producers, and the organism remains nearly universally susceptible to the macrolides, fluoroquinolones, tetracyclines and the combination of trimethoprim and sulfamethoxazole. Two major beta-lactamase forms, BRO-1 and BRO-2, have been described on the basis of their isoelectric focusing patterns. The BRO-1 enzyme is found in the majority of beta-lactamase-producing isolates and confers a higher level of resistance to strains than BRO-2. The BRO enzymes are membrane associated and their production appears to be mediated by chromosomal determinants which are transmissible by an unknown mechanism. The origin of these novel proteins is unknown.

Eradication of penicillin-resistant pneumococci in the nasopharynx with antibiotic combinations including rifampicin: experiences from the South Swedish Pneumococcal Intervention Project

39 children with prolonged nasopharyngeal carriage (48-328 days) of intermediately to highly penicillin-resistant pneumococci (PRP) were treated for 7 days with rifampicin in combination with amoxicillin (n = 18) erythromycin (n = 17) or clindamycin (n = 4), according to resistance pattern. In all children, except for 1 carrying a rifampicin-resistant strain, control cultures from the nasopharynx 1-2 weeks after the last antibiotic dosage, yielded no growth of PRP. In 2 brothers, PRP with the same serogroup and resistance pattern were found in nasopharynx 10 weeks after the antibiotic treatment. These preliminary findings indicate that antibiotic regimens including rifampicin are effective in eradicating nasopharyngeal carriage, but reappearance of the same strain may occur after several weeks. Such treatments should be given with caution due to the risk of selecting rifampicin-resistant strains. Further controlled studies are needed to determine the optimal combination of antibiotics and appropriate duration of therapy.

Duration of nasopharyngeal carriage of penicillin-resistant Streptococcus pneumoniae: experiences from the South Swedish Pneumococcal Intervention Project

As a part of an intervention project, all detected carriers of penicillin-resistant pneumococci (PRP) (MIC, > or = 0.5 mg/L) in Malmöhus County, southern Sweden, were followed by means of weekly nasopharyngeal cultures. The median duration of carriage in 678 individuals was 19 days (range, 3-267 days). The duration of carriage was longest in children < 1 year old (median, 30 days) and shortest in adults > 18 years old (median, 14 days). Index cases, whose cultures were performed during an acute infection, were carriers for a mean of 10 days longer than asymptomatic contact cases (P < .05). The PRP spontaneously disappeared from the nasopharynx within 4 weeks in 68%, within 8 weeks in 87%, and within 12 weeks in 94% of the individuals. Other significant risk factors for prolonged carriage were the occurrence of > 6 episodes of acute otitis media (AOM) or first episode of AOM before the age of 1 year (P < .01), the carriage of PRP by other family members (P < .05), and the obtainment of a first positive culture during the winter months (P < .05).

Enterobacter spp.: pathogens poised to flourish at the turn of the century

Knowledge of the genus Enterobacter and its role in human disease has expanded exponentially in recent years. The incidence of infection in the hospital and the community has increased. New clinical syndromes have been recognized. Enterobacter spp. have also been implicated as causes of other syndromes that traditionally have been associated almost exclusively with more easily treatable pathogens, such as group A streptococci and staphylococci. Rapid emergence of multiple-drug resistance has been documented in individual patients during therapy and in populations and environments with strong selective pressure from antimicrobial agents, especially the cephalosporins. Therapeutic options for patients infected with multiply resistant strains have become severely limited. Carbapenems or, alternatively, fluoroquinolones are the most predictively active options, although resistance to both classes has been observed on rare occasions. Enterobacter spp. appear well adapted for survival and even proliferation as the turn of the century approaches.

Activity of trovafloxacin against blood isolates of Streptococcus pneumoniae in Sweden

The in vitro activity of the fluoroquinolone trovafloxacin (CP-99,219) against 257 blood isolates of Streptococcus pneumoniae obtained from Swedish hospitals was compared with those of commonly prescribed oral antibiotics and also with those of ciprofloxacin and ofloxacin against a collection of strains resistant (n = 6) or intermediately resistant (n = 22) to penicillin (Pc-R). The MICs of trovafloxacin for Pc-R strains of pneumococci ranged from 0.032 to 0.25 mg/l. No difference was seen between the clinical isolates and the Pc-R strains (MIC50 = 0.064 mg/l and MIC90 = 0.125 mg/l for both collections). For the Pc-R strains, the MIC50 and MIC90 values of ciprofloxacin were 0.5 and 1 mg/l, and those of ofloxacin 2 and 4 mg/l. The incidence of resistance in the two collections (clinical isolates/Pc-R strains) was 3%/39% for tetracycline, 1%/18% for macrolides, and 3%/57% for trimethoprim/sulfamethoxazole. The results of the current study suggest that the clinical efficacy of trovafloxacin in the treatment of pneumococcal infections should be investigated.

Occurrence of pneumococci with resistance or decreased susceptibility to penicillin in southeast Sweden

The minimal inhibitory concentrations (MICs) of 14 beta-lactam and non-beta-lactam antibiotics were determined for all pneumococci with intermediate susceptibility (I), (n = 26) or resistance (R), (n = 15) to penicillin G isolated at the Clinical Microbiology Laboratory, University Hospital, Linköping, Sweden during 1994. These isolates accounted for 3% of all pneumococcal isolates. The results were compared with those of 26 penicillin-susceptible isolates. The MICs of all tested beta-lactam antibiotics increased with MICs of penicillin G. The least increase and the lowest MICs of these agents were recorded for cefotaxime and imipenem. 27% of I- and R-strains were multiple-resistant, most often to tetracycline, trimethoprim-sulfametoxazole, erythromycin, chloramphenicol and clindamycin. All strains were susceptible to vancomycin and rifampicin. I-strains belonged to at least 5 different serotypes. However, 12 of the 15 R-strains were serotype 9 and 6 of these were recovered during contact tracing, indicating spread of a single clone within day-care centres.