Epidemiology and in vitro susceptibility of drug-resistant Streptococcus pneumoniae

Ceftriaxone versus ampicillin for the treatment of community-acquired pneumonia. A propensity matched cohort study

OBJECTIVES

Ceftriaxone is recommended as first-line antibiotic treatment (with the addition of macrolide) for hospitalised adults with community acquired pneumonia (CAP). Narrower-spectrum β-lactam as ampicillin, may be associated with comparable clinical outcomes, with less emergence of resistant pathogens or Clostridioides difficile infection (CDI). We aimed to examine whether ampicillin and ceftriaxone (with the addition of macrolides for both arms) are comparable for the treatment of hospitalized adults due to CAP.

METHODS

This was a single center, observational cohort study. We included adult patients who were hospitalized in internal medicine wards due to CAP and were treated with either ceftriaxone or ampicillin with the addition of macrolide. A propensity-score model was used. The primary outcome was 30-day all-cause mortality. A multivariable logistic regression analysis and Kaplan-Meier survival analysis was performed. We performed subgroup analyses for the main outcome based on CURB-65 score and age.

RESULTS

A total of 1586 patients fulfilled the inclusion criteria. There was no difference in 30-day mortality rate in the total cohort (28/233 vs. 208/1353 in ampicillin and ceftriaxone arm, respectively; p = 0.184). In the propensity matched cohort (197 in ampicillin and 394 in ceftriaxone arm), there was no significant difference in 30-day all-cause mortality between treatment groups in multivariable analysis of the main model (OR 0.67, 95% CI, 0.37-1.2; p = 0.189) and Kaplan-Meier survival analysis (p = 0.108). Thirty-day mortality rate was (19/197 vs. 57/394, in ampicillin and ceftriaxone arms, respectively; p = 0.108) Patients who were treated with ampicillin experienced significantly lower rates of CDI (0/197, 0% vs. 8/394, 2%; p = 0.044).

DISCUSSION

Ampicillin was associated with comparable clinical outcomes in comparison to ceftriaxone for patients who were hospitalized due to CAP. Ampicillin was associated with significantly lower rate of CDI. Results need to be confirmed by more robust study designs.

Bacteriology and resistance patterns of otitis media with effusion

OBJECTIVES

Following the increased use of antibiotics, the emergence of antibiotic-resistant species in pediatric patients with otitis media has become a problem in recent years. The aim of this study was to investigate change in bacterial species, antibiotic resistance, and detection rate of highly pathogenic species, such as Methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa according to the number of repeated ventilation tube insertion (VTI) procedures in pediatric patients diagnosed with otitis media with effusion (OME).

MATERIALS & METHODS

From May 2010 to June 2018, 158 patients under 17 years of age who were admitted to the outpatient clinic of Kyung Hee Medical Center and diagnosed as OME and underwent unilateral or bilateral VTI were included in this study. Bacterial cultures were performed on aseptically collected middle ear effusion (MEF) at the time of VTI and antibiotic sensitivity tests were performed on the identified bacteria.

RESULTS

Bacteria were not identified in 195 (70.1%) cultures and identified in 83 (29.9%) cultures. Coagulase-negative staphylococci (CNS) was the most frequently detected species in both the non-recurrent group and the recurrent group. MRSA detection rate was found to be significantly higher in the recurrent group than in the non-recurrent group (p = 0.029). The two groups showed no significant difference in antibiotic resistance against all antibiotics (p > 0.05).

CONCLUSION

Staphylococcus species were detected most frequently in the MEF of pediatric OME patients, and the MRSA detection rate was higher in the recurrent group than in the non-recurrent group. There was no difference in antibiotic sensitivity between the two groups against all antibiotics, but resistance to penicillin G and cefoxitin was newly appeared in patients with repeated detection of same bacterial isolates.

Femtoliter droplet confinement of Streptococcus pneumoniae: bacterial genetic transformation by cell-cell interaction in droplets

Streptococcus pneumoniae (pneumococcus), a deadly bacterial human pathogen, uses genetic transformation to gain antibiotic resistance. Genetic transformation begins when a pneumococcal strain in a transient specialized physiological state called competence, attacks and lyses another strain, releasing DNA, taking up fragments of the liberated DNA, and integrating divergent genes into its genome. While many steps of the process are known and generally understood, the precise mechanism of this natural genetic transformation is not fully understood and the current standard strategies to study it have limitations in specifically controlling and observing the process in detail. To overcome these limitations, we have developed a droplet microfluidic system for isolating individual episodes of bacterial transformation between two confined cells of pneumococcus. By encapsulating the cells in a 10 μm diameter aqueous droplet, we provide an improved experimental model of genetic transformation, as both participating cells can be identified, and the released DNA is spatially restricted near the attacking strain. Specifically, the bacterial cells, one rifampicin (R) resistant, the other novobiocin (N) and spectinomycin (S) resistant were encapsulated in droplets carried by the fluorinated oil FC-40 with 5% surfactant and allowed to carry out competence-specific attack and DNA uptake (and consequently gain antibiotic resistances) within the droplets. The droplets were then broken, and recombinants were recovered by selective plating with antibiotics. The new droplet system encapsulated 2 or more cells in a droplet with a probability up to 71%, supporting gene transfer rates comparable to standard mixtures of unconfined cells. Thus, confinement in droplets allows characterization of natural genetic transformation during a strictly defined interaction between two confined cells.

High Prevalence of Antibiotic Resistance in Isolates from the Middle Meatus of Children and Adults with Acute Rhinosinusitis

Background

The pathogens in acute rhinosinusitis are similar worldwide. An increase in antibiotic resistance has been shown in a large number of studies in recent years. The prevalence of resistance varies greatly in different countries. This study was performed to determine the endemic prevalence of antibiotic resistance in pathogens of acute rhinosinusitis in Taiwan.

Methods

Middle meatus discharge was taken for aerobic culture in 133 outpatients with the diagnosis of acute rhinosinusitis.

Results

One hundred two isolates of pathogens were found, including three major bacteria: Haemophilus influenzae (37.3%), Streptococcus pneumoniae (28.4%), and Moraxella catarrhalis (11.8%). Polymicrobial infections and positive cultures occurred more frequently in pediatric patients, as did recovery of M. catarrhalis infection. An extremely high percentage of resistance to first-line antibiotics was noted, viz., penicillin-nonsusceptible S. pneumoniae (PNSSP) (72.4%), ampicillin-resistant H. influenzae (60.5%), and M. catarrhalis (58.3%).

Conclusion

The high prevalence of drug resistance is a great threat to public health. Antibiotic use should be more prudent, especially in pediatric patients, who were found to be more susceptible to bacterial rhinosinusitis and multiple pathogenic infection.

Pattern of Antibiotic Resistance ofStreptococcus pneumoniaein a Hospital in the Eastern Province of Saudi Arabia

The objective of the study was to evaluate the pattern of antibiotic resistance of Streptococcus pneumoniae at Saudi Aramco Medical Services Organization (SAMSO) in the Eastern Province of Saudi Arabia. We identified, retrospectively, S. pneumoniae isolates from January 1999 to December 2002. Antimicrobial susceptibility and clinical data were collected and analyzed. A total of 162 isolates of S. pneumoniae were identified in the study period. Of these isolates, 94 (58%) isolates were obtained from out-patients and 68 (42%) were obtained from in-patients. Thirty-five percent of isolates were from blood, 46% from the respiratory tract, and the remainder were obtained from other sites. Of these isolates, 83 (51%) were penicillin-susceptible and the remaining 79 (48.8%) were not penicillin susceptible. High-level resistance to penicillin existed in 19.8% of the total isolates. Prevalence of resistance to erythromycin, tetracycline and trimethoprim-sulfamethoxazole was 25%, 29%, and 42% respectively. None of the isolates was resistant to vancomycin or ceftriaxone. However, 12% of the isolates showed multi-drug resistance. Streptococcus pneumoniae shows 19.8% high-level penicillin resistance and 12% multi-drug resistance. These findings call for wiser use of antibiotics.

Microbiology of otitis media: a moving target

The microbiology of acute otitis media (AOM) is linked to the nasopharyngeal commensal flora. This respiratory ecosystem undergoes various selective pressures, such as antibiotic consumption and vaccine use. Socio-economic conditions also influence the bacterial composition of the nasopharynx. Streptococcus pneumoniae, non-encapsulated Haemophilus influenzae, Moraxella catarrhalis, and group A Streptococcus are the leading causes of bacterial AOM worldwide. This paper will discuss the causes and consequences of recent shifts in the underlying microbiology of AOM.

High Prevalence of Streptococcus pneumoniae with Mutations in pbp1a, pbp2x, and pbp2b Genes of Penicillin-Binding Proteins in the Nasopharynx in Children in Japan

OBJECTIVE

To evaluate the resistances of Streptococcus pneumoniae to beta-lactams developed by stepwise alterations in high-molecular-weight penicillin-binding proteins (PBPs) with a reduced binding affinity of beta-lactams. Among the numerous mutations in pbp genes that alter the affinity for beta-lactams, the decreased affinity of PBP1A, 2X and 2B is especially important in the development of resistances to beta-lactams.

STUDY DESIGN

Retrospective review.

METHODS

In this study, we investigated the mutations in pbp1a, pbp2x, and pbp2b genes evaluated by polymerase chain reaction (PCR) in 866 pneumococcal isolates collected from the nasopharynx of Japanese children with acute otitis media.

RESULTS

210 strains (24.3%) exhibited no mutations in the three pbp genes. 333 strains (38.5%) had mutations in the three pbp genes, 78 (9.0%) in two pbp genes, whereas 245 (28.3%) displayed mutations in only one pbp gene. Among the 656 strains with mutations in pbp genes, 620 (94.5%) strains had mutations in pbp2x. The annual prevalence of antimicrobial-resistant S. pneumoniae showed a gradual increase in strains with mutations in the three pbp genes and a parallel decrease in strains without mutations.

CONCLUSIONS

PCR-based genotyping can characterize the antimicrobial resistances in pneumococci along with minimal inhibitory concentrations (MICs). Physicians should pay attention to the recent increase in antimicrobial-resistant S. pneumoniae when treating pediatric acute otitis media.

Influenza and pneumococcal vaccination of the elderly in Taiwan

In 1998, Taiwan became the first country in Asia to provide free influenza vaccination to high-risk groups, mainly the elderly. The purpose of this study is to determine: (1) the annual mortality rate from influenza and pneumococcal-related illnesses such as pneumonia, chronic bronchitis, pulmonary emphysema and asthma and (2) the effectiveness of and adverse events associated with the influenza vaccination. In the elderly, influenza vaccination caused the annual death rate due chronic bronchitis, pulmonary emphysema, and asthma to decline steadily but had no effect on the annual pneumonia death rate. The only adverse effect of concern was vertigo (in approximately 2-3%).

Characterisation of invasive pneumococcal isolates in Catalan children up to 5 years of age, 1989–2000

Ninety-six Streptococcus pneumoniae strains isolated between January 1989 and December 2000 from usually sterile sites of children aged < 5 years of age were included in the study. Resistance to penicillin (38.6% intermediate, 10.4% high-level), cefotaxime (20.8%), tetracycline (41.7%), chloramphenicol (33.3%) and erythromycin (27.1%), as well as serogroup/type, were related to age and pathology. Strains from children aged < 2 years showed the highest penicillin resistance rate. Resistance to penicillin, tetracycline, chloramphenicol and erythromycin was the most common pattern (18.8% of strains). Most isolates (80.2%) belonged to serogroups/types included in the heptavalent conjugate vaccine.

Antimicrobial treatment guidelines for acute bacterial rhinosinusitis

Treatment guidelines developed by the Sinus and Allergy Health Partnership for acute bacterial rhinosinusitis (ABRS) were originally published in 2000. These guidelines were designed to: (1) educate clinicians and patients (or patients’ families) about the differences between viral and bacterial rhinosinusitis; (2) reduce the use of antibiotics for nonbacterial nasal/sinus disease; (3) provide recommendations for the diagnosis and optimal treatment of ABRS; (4) promote the use of appropriate antibiotic therapy when bacterial infection is likely; and (5) describe the current understanding of pharmacokinetic and pharmacodynamics and how they relate to the effectiveness of antimicrobial therapy. The original guidelines are updated here to include the most recent information on management principles, antimicrobial susceptibility patterns, and therapeutic options.

Burden of disease

An estimated 20 million cases of ABRS occur annually in the United States. According to National Ambulatory Medical Care Survey (NAMCS) data, sinusitis is the fifth most common diagnosis for which an antibiotic is prescribed. Sinusitis accounted for 9% and 21% of all pediatric and adult antibiotic prescriptions, respectively, written in 2002. The primary diagnosis of sinusitis results in expenditures of approximately $3.5 billion per year in the United States.

Definition and diagnosis of ABRS

ABRS is most often preceded by a viral upper respiratory tract infection (URI). Allergy, trauma, dental infection, or other factors that lead to inflammation of the nose and paranasal sinuses may also predispose individuals to developing ABRS.

Patients with a “common cold” (viral URI) usually report some combination of the following symptoms: sneezing, rhinorrhea, nasal congestion, hyposmia/anosmia, facial pressure, postnasal drip, sore throat, cough, ear fullness, fever, and myalgia. A change in the color or the characteristic of the nasal discharge is not a specific sign of a bacterial infection. Bacterial superinfection may occur at any time during the course of a viral URI. The risk that bacterial superinfection has occurred is greater if the illness is still present after 10 days. Because there may be cases that fall out of the “norm” of this typical progression, practicing clinicians need to rely on their clinical judgment when using these guidelines. In general, however, a diagnosis of ABRS may be made in adults or children with symptoms of a viral URI that have not improved after 10 days or worsen after 5 to 7 days. There may be some or all of the following signs and symptoms: nasal drainage, nasal congestion, facial pressure/pain (especially when unilateral and focused in the region of a particular sinus), postnasal drainage, hyposmia/anosmia, fever, cough, fatigue, maxillary dental pain, and ear pressure/fullness.

Physical examination provides limited information in the diagnosis of ABRS.

While sometimes helpful, plain film radiographs, computed tomography (CT), and magnetic resonance imaging scans are not necessary for cases of ABRS.

Microbiology of ABRS

The most common bacterial species isolated from the maxillary sinuses of patients with ABRS are Streptococcus pneumoniae , Haemophilus influenzae , and Moraxella catarrhalis , the latter being more common in children. Other streptococcal species, anaerobic bacteria and Staphylococcus aureus cause a small percentage of cases.

Bacterial resistance in ABRS

The increasing prevalence of penicillin nonsusceptibility and resistance to other drug classes among S pneumoniae has been a problem in the United States, with 15% being penicillin-intermediate and 25% being penicillin-resistant in recent studies. Resistance to macrolides and trimethoprim/sulfamethoxazole (TMP/SMX) is also common in S pneumoniae . The prevalence of β-lactamase-producing isolates of H influenzae is approximately 30%, while essentially all M catarrhalis isolates produce β-lactamases. Resistance of H influenzae to TMP/SMX is also common.

Antimicrobial treatment guidelines for ABRS

These guidelines apply to both adults and children. When selecting antibiotic therapy for ABRS, the clinician should consider the severity of the disease, the rate of progression of the disease, and recent antibiotic exposure. The guidelines now divide patients with ABRS into two general categories: (1) those with mild symptoms who have not received antibiotics within the past 4 to 6 weeks, and (2) those with mild disease who have received antibiotics within the past 4 to 6 weeks or those with moderate disease regardless of recent antibiotic exposure. The difference in severity of disease does not imply infection with a resistant pathogen. Rather, this terminology indicates the relative degree of acceptance of possible treatment failure and the likelihood of spontaneous resolution of symptoms—patients with more severe symptoms are less likely to resolve their disease spontaneously. The primary goal of antibiotic therapy is to eradicate bacteria from the site of infection, which, in turn, helps (1) return the sinuses back to health; (2) decrease the duration of symptoms to allow patients to resume daily activities more quickly; (3) prevent severe complications such as meningitis and brain abscess; and (4) decrease the development of chronic disease. Severe or life-threatening infections with or without complications are rare, and are not addressed in these guidelines.

Prior antibiotic use is a major risk factor associated with the development of infection with antimicrobial-resistant strains. Because recent antimicrobial exposure increases the risk of carriage of and infection due to resistant organisms, antimicrobial therapy should be based upon the patient’s history of recent antibiotic use. The panel’s guidelines, therefore, stratify patients according to antibiotic exposure in the previous 4 to 6 weeks.

Lack of response to therapy at ≥72 hours is an arbitrary time established to define treatment failures. Clinicians should monitor the response to antibiotic therapy, which may include instructing the patient to call the office or clinic if symptoms persist or worsen over the next few days.

The predicted bacteriologic and clinical efficacy of antibiotics in adults and children has been determined according to mathematical modeling of ABRS developed by Michael Poole, MD, PhD, based on pathogen distribution, resolution rates without treatment, and in vitro microbiologic activity.

Antibiotics can be placed into the following relative rank order of predicted clinical efficacy for adults: 90% to 92% = respiratory fluoroquinolones (gatifloxacin, levofloxacin, moxifloxacin), ceftriaxone, high-dose amoxicillin/clavulanate (4 g/250 mg/day), and amoxicillin/clavulanate (1.75 g/250 mg/day); 83% to 88% = high-dose amoxicillin (4 g/day), amoxicillin (1.5 g/day), cefpodoxime proxetil, cefixime (based on H influenzae and M catarrhalis coverage), cefuroxime axetil, cefdinir, and TMP/SMX; 77% to 81% = doxycycline, clindamycin (based on gram-positive coverage only), azithromycin, clarithromycin and erythromycin, and telithromycin; 65% to 66% = cefaclor and loracarbef. The predicted spontaneous resolution rate in patients with a clinical diagnosis of ABRS is 62%.

Antibiotics can be placed into the following relative rank order of predicted clinical efficacy in children with ABRS: 91% to 92% = ceftriaxone, high-dose amoxicillin/clavulanate (90 mg/6.4 mg per kg per day) and amoxicillin/clavulanate (45 mg/6.4 mg per kg per day); 82% to 87% = high-dose amoxicillin (90 mg/kg per day), amoxicillin (45 mg/kg per day), cefpodoxime proxetil, cefixime (based on H influenzae and M catarrhalis coverage only), cefuroxime axetil, cefdinir, and TMP/SMX; and 78% to 80% = clindamycin (based on gram-positive coverage only), cefprozil, azithromycin, clarithromycin, and erythromycin; 67% to 68% = cefaclor and loracarbef. The predicted spontaneous resolution rate in untreated children with a presumed diagnosis of ABRS is 63%.

Recommendations for initial therapy for adult patients with mild disease (who have not received antibiotics in the previous 4 to 6 weeks) include the following choices: amoxicillin/clavulanate (1.75 to 4 g/250 mg per day), amoxicillin (1.5 to 4 g/day), cefpodoxime proxetil, cefuroxime axetil, or cefdinir. While TMP/SMX, doxycycline, azithromycin, clarithromycin, erythromycin, or telithromycin may be considered for patients with β-lactam allergies, bacteriologic failure rates of 20% to 25% are possible. Failure to respond to antimicrobial therapy after 72 hours should prompt either a switch to alternate antimicrobial therapy or reevaluation of the patient (see Table 4).When a change in antibiotic therapy is made, the clinician should consider the limitations in coverage of the initial agent.

Recommendations for initial therapy for adults with mild disease who have received antibiotics in the previous 4 to 6 weeks or adults with moderate disease include the following choices: respiratory fluoroquinolone (eg, gatifloxacin, levofloxacin, moxifloxacin) or high-dose amoxicillin/clavulanate (4 g/250 mg per day). The widespread use of respiratory fluoroquinolones for patients with milder disease may promote resistance of a wide spectrum of organisms to this class of agents. Ceftriaxone (parenteral, 1 to 2 g/day for 5 days) or combination therapy with adequate gram-positive and negative coverage may also be considered. Examples of appropriate regimens of combination therapy include high-dose amoxicillin or clindamycin plus cefixime, or high-dose amoxicillin or clindamycin plus rifampin. While the clinical effectiveness of ceftriaxone and these combinations for ABRS is unproven; the panel considers these reasonable therapeutic options based on the spectrum of activity of these agents and on data extrapolated from acute otitis media studies. Rifampin should not be used as monotherapy, casually, or for longer than 10 to 14 days, as resistance quickly develops to this agent. Rifampin is also a well-known inducer of several cytochrome p450 isoenzymes and therefore has a high potential for drug interactions. Failure of a patient to respond to antimicrobial therapy after 72 hours of therapy should prompt either a switch to alternate antimicrobial therapy or reevaluation of the patient (see Table 4). When a change in antibiotic therapy is made, the clinician should consider the limitations in coverage of the initial agent. Patients who have received effective antibiotic therapy and continue to be symptomatic may need further evaluation. A CT scan, fiberoptic endoscopy or sinus aspiration and culture may be necessary.

Recommendations for initial therapy for children with mild disease and who have not received antibiotics in the previous 4 to 6 weeks include the following: high-dose amoxicillin/clavulanate (90 mg/6.4 mg per kg per day), amoxicillin (90 mg/kg per day), cefpodoxime proxetil, cefuroxime axetil, or cefdinir. TMP/SMX, azithromycin, clarithromycin, or erythromycin is recommended if the patient has a history of immediate Type I hypersensitivity reaction to β-lactams. These antibiotics have limited effectiveness against the major pathogens of ABRS and bacterial failure of 20% to 25% is possible. The clinician should differentiate an immediate hypersensitivity reaction from other less dangerous side effects. Children with immediate hypersensitivity reactions to β-lactams may need: desensitization, sinus cultures, or other ancillary procedures and studies. Children with other types of reactions and side effects may tolerate one specific β-lactam, but not another. Failure to respond to antimicrobial therapy after 72 hours should prompt either a switch to alternate antimicrobial therapy or reevaluation of the patient (see Table 5).When a change in antibiotic therapy is made, the clinician should consider the limitations in coverage of the initial agent.

The recommended initial therapy for children with mild disease who have received antibiotics in the previous 4 to 6 weeks or children with moderate disease is high-dose amoxicillin/clavulanate (90 mg/6.4 mg per kg per day). Cefpodoxime proxetil, cefuroxime axetil, or cefdinir may be used if there is a penicillin allergy (eg, penicillin rash); in such instances, cefdinir is preferred because of high patient acceptance. TMP/SMX, azithromycin, clarithromycin, or erythromycin is recommended if the patient is β-lactam allergic, but these do not provide optimal coverage. Clindamycin is appropriate if S pneumoniae is identified as a pathogen. Ceftriaxone (parenteral, 50 mg/kg per day for 5 days) or combination therapy with adequate gram-positive and -negative coverage may also be considered. Examples of appropriate regimens of combination therapy include high-dose amoxicillin or clindamycin plus cefixime, or high-dose amoxicillin or clindamycin plus rifampin. The clinical effectiveness of ceftriaxone and these combinations for ABRS is unproven; the panel considers these reasonable therapeutic options based on spectrum of activity and on data extrapolated from acute otitis media studies. Rifampin should not be used as monotherapy, casually, or for longer than 10 to 14 days as resistance quickly develops to this agent. Failure to respond to antimicrobial therapy after 72 hours of therapy should prompt either a switch to alternate antimicrobial therapy or reevaluation of the patient (see Table 5). When a change in antibiotic therapy is made, the clinician should consider the limitations in coverage of the initial agent. Patients who have received effective antibiotic therapy and continue to be symptomatic may need further evaluation. A CT scan, fiberoptic endoscopy or sinus aspiration and culture may be necessary.

Invasive pneumococcal infections: a clinical and microbiological analysis of 53 patients in Taiwan

OBJECTIVE

To track penicillin susceptibility among Streptococcus pneumoniae causing invasive diseases and to evaluate risk factors for antibiotic resistance.

METHODS

A retrospective study was performed in a medical center of all patients with invasive pneumococcal infections based on positive microbiological findings, confirmed by appropriate clinical and laboratory findings. MICs of penicillin and ceftriaxone were determined and interpreted by NCCLS methodology.

RESULTS

Fifty-three episodes of invasive S. pneumoniae infections (ISPI) among 22 children and 31 adults were identified. The disease patterns of ISPI were similar between children and adults, and the most common modes were pneumonia (70%) and primary bacteremia (23%). The rate of penicillin-nonsusceptible S. pneumoniae (PNSP) isolated from pediatric patients was higher than that in adult patients (95.5% vs. 54.8%, P < 0.001). This finding was correlated to prior antibiotic use that was more common in children (36.4%) than in adults (18.9%). The rate of penicillin-resistance among S. pneumoniae isolates (PRSP) was extremely high in this area: 45.5% from pediatric patients and 41.9% from adult patients. More adults (90.3%) with ISPI had major underlying diseases than children (4.5%). This may explain why adult patients tended to run an unfavorable outcome (mortality rate, 51.6% and 4.5% in adults and children, respectively), although most of the cases with empyema were children. None of the patients enrolled in this study received pneumococcal vaccination.

CONCLUSION

We suggest that vaccines be administered for young children and the elderly with major underlying diseases to prevent ISPI.

Effectiveness of an educational intervention in modifying parental attitudes about antibiotic usage in children

OBJECTIVE

To determine the effectiveness of educational materials in improving the attitudes of parents of young children about the judicious use of antibiotics.

METHODS

We conducted a randomized controlled trial by recruiting parents of children who were younger than 24 months and being seen for any reason in primary care pediatric offices. At the time of enrollment, study parents indicated their level of agreement with 16 statements, including 9 statements about antibiotic usage and 7 about injury prevention. After being randomized, parents received either a pamphlet and a videotape promoting the judicious use of antibiotics (intervention group) or brochures about effective injury prevention (control group). Six weeks after enrollment, each group received another copy of the pamphlet or brochures and a follow-up questionnaire with the identical 16 statements. Responses on both questionnaires were transformed to an ordinal scale for analysis. Scores on the follow-up questionnaire for each statement about antibiotic use and injury prevention in the 2 groups were compared using linear regression, after controlling for the score obtained for the statement at enrollment.

RESULTS

We enrolled a total of 499 eligible parents in the study; 358 (72%) completed the follow-up questionnaires. At study entry, there were no significant differences between parents in the intervention and control groups regarding attitudes for 15 of the 16 statements assessed. However, 6 weeks after receiving the antibiotic educational materials, parents in the intervention group had significantly different attitude scores for 5 of the 9 statements about the antibiotic use. In each case, the scores reflected attitudes that would promote the judicious use of antibiotics. We found significant attitudinal change for statements about the use of antibiotics for specific conditions in children; there were no differences between the 2 groups for more general or theoretical statements about antibiotic use.

CONCLUSIONS

A simple educational effort was successful in modifying parental attitudes about the judicious use of antibiotics. Information about specific childhood conditions may be more effective in changing attitudes than more general information about antibiotic usage.

Immune response to octavalent diphtheria- and tetanus-conjugated pneumococcal vaccines is serotype- and carrier-specific: the choice for a mixed carrier vaccine

BACKGROUND

Development of protein-conjugated pneumococcal vaccines for infants has led to formulations that are immunogenic in the age group at highest risk for pneumococcal diseases. This study focuses on the search for an optimal formulation.

METHODS

In a randomized trial Icelandic infants (n = 160) were immunized at age 3, 4 and 6 months with one of two octavalent pneumococcal conjugate vaccines (serotypes 3, 4, 6B, 9V, 14, 18C, 19F and 23F conjugated to diphtheria toxoid (PncD) or tetanus protein (PncT) followed with a booster of either the same conjugate or 23-valent polysaccharide vaccine at 13 months. Safety data were collected after each vaccination, and IgG responses (enzyme-linked immunosorbent assay) were measured at 3, 4, 6, 7, 13 and 14 months.

RESULTS

Both conjugates were safe and caused fewer local reactions than the routine vaccines (P < 0.0001). At 7 months both groups had significant IgG response to all serotypes. The geometric mean concentration range was 0.35 to 4.09 and 0.65 to 3.38 microg/ml for PncD and PncT, respectively, with 88.2 to 100% and 92.4 to 100% of subjects reaching > or = 0.15 microg/ml. The PncD gave better primary responses to serotypes 3, 9V and 18C, whereas PncT gave better response to serotype 4. Similar responses were induced to the other serotypes. Good booster IgG responses were obtained in all vaccine groups; 97.5 to 100% of subjects reached > or = 1 microg/ml.

CONCLUSIONS

Both octavalent pneumococcal conjugates were safe and immunogenic in infants. Based on the results from this and similar trials, a mixed diphtheria and tetanus pneumococcal conjugate vaccine was designed to provide the optimal immune response to each serotype.

Antimicrobial guidelines for the treatment of acute bacterial rhinosinusitis in immunocompetent children

Acute rhinosinusitis represents a condition for which educational efforts could help minimize the inappropriate use of antibiotics, particularly for children. The majority of acute rhinosinusitis cases are of viral etiology and thus, are self limiting. Although bacterial infection complicates a small number of cases, the lack of accessibility to the sinus, the limitations of diagnostic modalities and the lack of specificity among signs and symptoms often make it difficult to determine when bacterial infection occurs. Furthermore, antimicrobial resistance among the pathogens that frequently cause bacterial infection complicates the election of empiric therapy. The Sinus and Allergy Health Partnership recently developed and published antimicrobial guidelines to provide practitioners in the US with recommendations for the diagnosis and treatment of acute bacterial rhinosinusitis. The purpose of this paper is to review the rationale behind the development of these guidelines and how they apply to the management of acute bacterial rhinosinusitis in children.

Broth microdilution and E-test for determining fluoroquinolone activity against Streptococcus pneumoniae

OBJECTIVE

To compare broth microdilution and E-test minimum inhibitory concentrations (MICs) of 4 fluoroquinolones against Streptococcus pneumoniae and to determine the effect of these in vitro MIC methods on the calculation of AUC00-24/MIC ratios.

METHODS

Levofloxacin, gatifloxacin, moxifloxacin, and gemifloxacin MICs were determined by broth microdilution (incubated in air) and E-test (incubated in CO2) for 100 clinical isolates of S. pneumoniae. MIC50, MIC90, and geometric mean MIC were calculated. Steady-state serum concentration-time profiles were simulated for once-daily, oral dosing of levofloxacin 500 mg, gatifloxacin 400 mg, moxifloxacin 400 mg, and gemifloxacin 320 mg. After correcting for protein binding, AUC0-24 of unbound drug was calculated for each regimen, and AUC0-24/MIC ratios were calculated using MIC data from both in vitro methods. Differences in MICs between methods were determined for each agent using the paired t-test (after logarithmic transformation of MICs) and the Wilcoxon signed-rank test. Differences in AUC0-24/MIC ratios were also determined using the paired t-test and the Wilcoxon signed-rank test. The level of significance for all analyses was p < 0.05.

RESULTS

Broth microdilution and E-test MICs were within +/- 1 log2 dilution for 94%, 93%, 61%, and 35% of the isolates for levofloxacin, gatifloxacin, moxifloxacin, and gemifloxacin, respectively. Broth microdilution MICs were significantly lower than E-test MICs for all 4 agents (p < 0.001). However, a categorical change in susceptibility was seen for only 1 isolate with gatifloxacin and moxifloxacin (intermediate by broth microdilution, resistant by E-test). AUC0-24/MIC ratios were significantly higher for each regimen when MICs were determined by broth microdilution compared with E-test (p < 0.001).

CONCLUSIONS

There is a significant difference in the activity of the newer fluoroquinolones against S. pneumoniae when MICs are determined by broth microdilution and E-test. When evaluating fluoroquinolone activity and pharmacodynamics against this organism, clinicians must be aware that MIC testing methodology may have a significant impact on the results.

Penicillin-resistant pneumococci-implications for management of community-acquired pneumonia and meningitis

Penicillin-nonsusceptible Streptococcus pneumoniae isolates have become increasingly prevalent worldwide. They are well-known agents of community-acquired infections such as otitis media, pneumonia and bacterial meningitis. Therapy of pneumococcal infections is made difficult by the emergence and spread of bacterial resistance to penicillin and other beta-lactams, as well as other antimicrobials such as macrolides. This article reviews current concepts of epidemiology and the implications of penicillin-nonsusceptible pneumococci for management of community-acquired pneumonia and meningitis.

Comparative in-vitro activity of penicillin alone and combined with gentamicin against clinical isolates of Streptococcus pneumoniae with decreased susceptibility to penicillin

The worldwide emergence of Streptococcus pneumoniae with decreased susceptibility to penicillin has led to the suggestion that drug combinations might be used. The aim of this study was to determine possible synergy using a combination of penicillin with sub-inhibitory doses of gentamicin against 26 clinical isolates of S. pneumoniae with decreased susceptibility to penicillin, using half-chequerboards and killing curves. Synergy was demonstrated for ten of the 26 isolates with the combination of penicillin with gentamicin at 1 mg/l and for 22 isolates with penicillin and gentamicin at 2 mg/l. Killing curves on three isolates showed synergy and confirmed the chequerboard results. Further synergy studies using penicillin or cefotaxime/ceftriaxone, plus low dose gentamicin against penicillin-resistant pneumococci are indicated.

Population-based survey of antimicrobial susceptibility and serotype distribution of Streptococcus pneumoniae from meningitis patients in Salvador, Brazil

Penicillin-nonsusceptible strains were isolated from 15% of 303 individuals with pneumococcal meningitis identified during a 4-year surveillance study in Salvador, Brazil. The estimated rate of coverage of the seven-valent conjugate vaccine was 74% among patients <5 years of age and 94% among those infected with nonsusceptible isolates, indicating that the use of conjugate vaccines may be an approach to the control of emerging penicillin resistance in Brazil.

Nasopharyngeal carriage of drug-resistant Streptococcus pneumoniae in children with acute otitis media evaluated by polymerase chain reaction-based genotyping of penicillin-binding proteins

A polymerase chain reaction (PCR)-based genotyping of the penicillin-binding protein (PBP) genes pbp1a, pbp2x and pbp2b was used to characterize Streptococcus pneumoniae isolated from the nasopharynx of children with acute otitis media (AOM). Mutations were observed in pbp1a, pbp2x and pbp2b genes in 36.5% of the strains. Decreased susceptibility to beta-lactam antibiotics was closely associated with the frequency of mutations in the three PBP genes. Of penicillin-intermediately-resistant S. pneumoniae strains, 54.5% appeared to be genetically similar to penicillin-resistant S. pneumoniae strains. Of penicillin-susceptible S. pneumoniae strains, 33.3% had mutations in the pbp2x gene and showed relatively high MICs to cephalosporins. Strains with mutations in the three PBP genes were often isolated from children < or = 2 years old. Evaluation of mutations in PBP genes using PCR will prove useful for studying the epidemiology of antibiotic resistance.

Pneumococcal bacteremia in adults in Soweto, South Africa, during the course of a decade

We retrospectively reviewed 414 episodes of pneumococcal bacteremia that occurred in adults from July 1986 through June 1987 (1986/1987) and from July 1996 through June 1997 (1996/1997) to monitor the incidence and clinical and laboratory characteristics and to assess the influence of human immunodeficiency virus (HIV) infection on any changes. The incidence increased from 26 per 100,000 persons in 1986/1987 to 36 per 100,000 persons in 1996/1997; the increase was most marked among patients who were aged 25-44 years (24 cases per 100,000 persons to 45 per cases 100,000 persons) and > or =65 years (43 cases per 100,000 persons to 50 cases per 100,000 persons). Of 161 patients who were tested for HIV in 1996/1997, 108 (67%) were HIV seropositive. Among the general population, the prevalence of other underlying diseases and smoking decreased from 45% and 67%, respectively, in 1986/1987 to 23% (P<.0001) and 35% (P<.0001) in 1996/1997. Strains of pneumococci that were not susceptible to penicillin were found in 4% patients in 1986/1987 and 12% in 1996/1997 (P=.005). This increase occurred exclusively among the HIV-infected patients (22% of the HIV-seropositive patients versus 4% of HIV-seronegative patients; P=.008), and there was a parallel increase for childhood serotypes (51% of HIV-seropositive patients versus 17% of HIV-seronegative patients; P<.0001).

Investigation of risk factors for penicillin-resistant Streptococcus pneumoniae carriage in Turkish children

BACKGROUND

Nasopharyngeal colonization plays an important role for infections caused by Streptococcus pneumoniae. Emergence of penicillin resistance in this organism has made it difficult to treat pneumococcal infections. The objectives of this study were to investigate the risk factors for nasopharyngeal colonization with S. pneumonia and for nasopharyngeal colonization with penicillin-resistant S. pneumoniae.

METHODS

Three hundred children with or without evidence of infection were investigated for various risk factors. Streptococcus pneumoniae isolated from children's nasopharyngeal swabs were examined for penicillin susceptibility.

RESULTS

Day-care attendance (odds ratio OR=2.82, P=0.003) and upper respiratory tract infection within the last month (OR=1.83, P=0.02), have been determined to be risk factors for S. pneumoniae carriage. The use of antibiotics within the last 3 months (OR=81.07, P<0.001), the presence of more than five people living in the house of the child (OR=6.63, P=0.03), and having a sibling under 5-years-old (OR=4.60, P=0.03) have been determined to be risk factors for penicillin-resistant S. pneumoniae carriage.

CONCLUSION

Some children are inevitably exposed to and colonized with penicillin susceptible or resistant S. pneumoniae. Changes in day-care organizations, better living conditions, and restriction of antibiotic use seems to be useful precautions to prevent the emerging and colonization with penicillin-susceptible or -resistant S. pneumoniae.

Prevalence of penicillin-resistant Streptococcus pneumoniae in Kuwait

The worldwide incidence of penicillin-resistant Streptococcus pneumoniae has increased at an alarming rate during the past decade. However, there has been little published data about the extent of this problem in Kuwait. The present study was undertaken to ascertain the preponderance of S. pneumoniae, either resistant or intermediate-resistant to penicillin, other beta-lactams and non-beta-lactam antimicrobials in Kuwait. Two hundred and fifty fresh isolates from as many patients suffering from different clinical conditions were collected from all clinics and hospitals in Kuwait. Optochin sensitivity and bile solubility tests reconfirmed these. Susceptibility testing to penicillin, ampicillin, cefuroxime, ceftriaxone, cefotaxime, imipenem, erythromycin, chloramphenicol, ciprofloxacin and vancomycin was done using E-test strips and to oxacillin, tetracycline, trimethoprim and amoxicillin-clavulanate by disc diffusion technique. Full and intermediate resistance to penicillin was observed in 1.6% and 52.8% of the isolates respectively. Full resistance to third-generation cephalosporins ranged from 0.4% to 3.2%, however, intermediate resistance to these antibiotics varied between 18.8% and 21.2%. Ampicillin resistance was noted in 0.8%, but 40.4% of isolates were intermediately resistant. However, only 0.4% of the isolates showed either intermediate or full resistance to amoxicillin-clavulanate. Resistance to imipenem was observed in 0.4% and intermediate to 13.6% of the organisms. The rates of S. pneumoniae resistant to chloramphenicol, erythromycin, tetracycline and trimethoprim were between 8.4% and 37.6% and intermediate resistance between 1.2% and 17.6% while only 0.4% showed resistance to ciprofloxacin and none to vancomycin. Multiresistance to both beta-lactam and non-beta-lactam antibiotics was observed in 52% of the penicillin-resistant isolates.

In vitro activity and pharmacodynamics of azithromycin and clarithromycin against Streptococcus pneumoniae based on serum and intrapulmonary pharmacokinetics

BACKGROUND

Multidrug-resistant strains of Streptococcus pneumoniae are increasingly common worldwide, but the clinical significance of their resistance to the macrolide antibiotics is controversial. Applying pharmacokinetic and pharmacodynamic principles can assist in the selection of appropriate antimicrobial therapy.

OBJECTIVES

The purpose of this study was to determine the in vitro activity of penicillin, azithromycin, clarithromycin, and clindamycin against clinical isolates of S. pneumoniae and to evaluate the pharmacodynamics of azithromycin and clarithromycin based on serum and epithelial lining fluid (ELF) concentrations.

METHODS

The minimum inhibitory concentrations (MICs) of penicillin, azithromycin, clarithromycin, and clindamycin were determined for 307 isolates of S. pneumoniae using broth microdilution. Using serum and ELF concentrations after standard dosing, we calculated the proportion of isolates against which it would be possible to obtain a ratio of azithromycin area under the curve to MIC > or =25 and clarithromycin concentrations that exceeded the MIC for > or =40% of the dosing interval.

RESULTS

Overall, 19.5%, 25.4%, 25.1%, and 7.2% of the 307 pneumococcal isolates were resistant to penicillin, azithromycin, clarithromycin, and clindamycin, respectively. However, 71.7% of penicillin-resistant strains were also resistant to azithromycin and clarithromycin. Based on serum concentrations, clarithromycin achieved its pharmacodynamic target in 76.9% of isolates, compared with 59.9% for azithromycin. Based on ELF concentrations, clarithromycin achieved its pharmacodynamic target in 93.5% of isolates, compared with 74.6% for azithromycin. Based on ELF concentrations, clarithromycin achieved its pharmacodynamic target in 86.7% of penicillin-resistant isolates, compared with 28.3% for azithromycin.

CONCLUSIONS

On the basis of serum and ELF concentrations, clarithromycin achieved pharmacodynamic targets against a greater proportion of S. pneumoniae isolates than did azithromycin. Clinical studies are needed to determine the efficacy of these agents against pneumococci that demonstrate in vitro resistance using current susceptibility breakpoints.

Two-year surveillance of antibiotic resistance in Streptococcus pneumoniae in four African cities

Worldwide spread of antibiotic resistance in Streptococcus pneumoniae is a major problem. However, data from West and North African countries are scarce. To study the level of resistance and compare the situations in different cities, a prospective study was conducted in Abidjan (Ivory Coast), Casablanca (Morocco), Dakar (Senegal), and Tunis (Tunisia), from 1996 to 1997. The resistances to eight antibiotics of 375 isolates were studied by E test, and the results were interpreted using the breakpoints recommended by the National Committee for Clinical Laboratory Standards. Overall, 30.4% of the isolates were nonsusceptible to penicillin G (25.6% were intermediate and 4.8% were resistant). Amoxicillin (96.3% were susceptible) and parenteral third-generation cephalosporins (92.7%) were highly active. Resistance to chloramphenicol was detected in 8.6% of the isolates. High levels of resistance were noted for erythromycin (28%), tetracycline (38.3%), and cotrimoxazole (36.4%). Resistance to rifampin was rare (2.1%). There were significant differences in resistance rates between individual countries. Multiple resistance was more frequent in penicillin-nonsusceptible isolates than in penicillin-susceptible isolates. Recommendations for treatment could be generated from these results in each participating country.

The role of respiratory viruses in otitis media

Evidence derived from numerous studies ranging from animal experiments to extensive clinical trials supports a crucial role for respiratory viruses in acute otitis media. Viral infection of the upper respiratory tract initiates the whole cascade of events that ultimately leads to development of acute otitis media, and viruses contribute to the pathogenesis of this disease by several mechanisms. Recent data indicate that at least some types of viruses actively invade the middle ear and may also interfere with the outcome of otitis media. The availability of effective vaccines against the principal viruses predisposing to acute otitis media could be expected to result in a substantial reduction in the incidence of this disease.

Antimicrobial resistance in Streptococcus pneumoniae: implications for patients with community-acquired pneumonia

Streptococcus pneumoniae is the leading cause of community-acquired pneumonia. During the past decade, the prevalence of penicillin resistance in S pneumoniae has increased dramatically, with resistance rates approaching 45% in some areas of the United States. Streptococcus pneumoniae has also acquired resistance to other commonly used antimicrobials, including cephalosporins, macrolides, and trimethoprim-sulfamethoxazole. While vancomycin and the newer quinolones are currently highly active against most strains of S pneumoniae, reduced susceptibilities to these agents have been identified in some strains. Prior use of antimicrobial agents is the major risk factor for colonization and infection with antibiotic-resistant strains. beta-Lactam antibiotics remain the treatment of choice for infections caused by susceptible S pneumoniae. The optimum therapy for penicillin-resistant strains remains unclear. Appropriate empirical therapy for patients with community-acquired pneumonia depends in part on the community-specific resistance patterns of S pneumoniae to various antibiotics. In this article, we provide an overview of the development of S pneumoniae resistance to commonly used antibiotics and discuss the implications of the development of resistance on treatment decisions.

Comparative in vitro activity and pharmacodynamics of five fluoroquinolones against clinical isolates of Streptococcus pneumoniae

STUDY OBJECTIVE

To compare in vitro activity and pharmacodynamics of five fluoroquinolones against clinical isolates of Streptococcus pneumoniae.

DESIGN

In vitro analysis.

SETTING

University research laboratory.

INTERVENTION

Minimum inhibitory concentrations (MICs) were determined for penicillin and five fluoroquinolones by E test for 201 S. pneumoniae isolates. Serum concentration-time profiles were simulated for the following regimens: ciprofloxacin 750 mg orally every 12 hours and 400 mg intravenously every 8 hours; levofloxacin 500 mg orally and intravenously every 24 hours; trovafloxacin 200 mg orally and intravenously every 24 hours; gatifloxacin 400 mg orally and intravenously every 24 hours; and clinafloxacin 200 mg orally and intravenously every 12 hours.

MEASUREMENTS AND MAIN RESULTS

Free 24-hour areas under the serum concentration-time curves (AUC0-24) were calculated using the trapezoidal rule, and the average AUC0-24:MIC ratio was calculated for each regimen. Differences in ratios among agents were determined by analysis of variance (Scheffe post hoc test, p < 0.05). For intravenous dosing, the average AUC0-24:MIC for gatifloxacin, clinafloxacin, trovafloxacin, ciprofloxacin, and levofloxacin was 146, 142, 122, 71, and 61, respectively. For both oral and intravenous regimens, gatifloxacin and clinafloxacin ratios were significantly greater than those for trovafloxacin, levofloxacin, and ciprofloxacin (p < or = 0.007). Ratios for trovafloxacin were significantly greater than those for levofloxacin and ciprofloxacin (p < 0.0001), and levofloxacin and ciprofloxacin ratios were not significantly different from each other.

CONCLUSION

Gatifloxacin and clinafloxacin achieve significantly higher AUC0-24:MIC ratios for S. pneumoniae than trovafloxacin, levofloxacin, and ciprofloxacin. Large comparative studies are necessary to determine the clinical significance of these findings.

Bacteriologic and clinical efficacy of one day vs. three day intramuscular ceftriaxone for treatment of nonresponsive acute otitis media in children

BACKGROUND

One dose of intramuscular ceftriaxone has been recently licensed in the United States for the treatment of acute otitis media. However, data regarding the bacteriologic and clinical efficacy of this regimen in the treatment of nonresponsive acute otitis media are incomplete.

OBJECTIVES

To determine the bacteriologic and clinical efficacy of a 1-day 50-mg/kg vs. a 3-day 50-mg/kg/day intramuscular ceftriaxone regimen in the treatment of nonresponsive acute otitis media in children.

PATIENTS AND METHODS

In an open, prospective study 109 patients ages 3 to 36 months with culture-proved, nonresponsive acute otitis media were randomized to receive 1 (n = 49) or 3 (n = 60) 50-mg/kg/day intramuscular ceftriaxone doses, respectively. Middle ear fluid was aspirated for culture by tympanocentesis on the day of enrollment (Day 1); a second tympanocentesis with middle ear fluid culture was performed on Days 4 to 5. Additional middle ear fluid cultures were obtained if clinical relapse occurred after completion of therapy. Bacteriologic failure was defined by positive cultures on Days 4 to 5. Patients were followed until Day 28 after completion of therapy. Susceptibility of the middle ear pathogens was measured by E-test.

RESULTS

Organisms recovered (n = 133) were Streptococcus pneumoniae (30 and 35 isolates for the 1-day and 3-day treatment group, respectively), Haemophilus influenzae (26 and 38, respectively) and Moraxella catarrhalis (n = 4). Of the 30 S. pneumoniae isolated from the 1-day group, 27 (90%) and 6 (20%) were nonsusceptible to penicillin and ceftriaxone, respectively; 9 of 27 (33%) were fully resistant to penicillin. Thirty-four (97%) and 6 (17%) of the 35 S. pneumoniae isolated from the 3-day group were nonsusceptible to penicillin and ceftriaxone, respectively; 16 of 34 (47%) were fully resistant to penicillin. Bacterial eradication of all H. influenzae and penicillin-susceptible S. pneumoniae was achieved in both treatment groups. Bacterial eradication of 14 of 27 (52%) and 33 of 34 (97%) penicillin-nonsusceptible S. pneumoniae was achieved in the 1-day and 3-day group, respectively. Seven (50%) of the 14 patients from the 2 groups who did not achieve bacterial eradication did not improve clinically on Days 4 to 5 and required additional ceftriaxone treatment.

CONCLUSION

The 3-day intramuscular ceftriaxone regimen was significantly superior to the 1-day intramuscular ceftriaxone regimen in the treatment of nonresponsive acute otitis media caused by penicillin-resistant S. pneumoniae.

Nasopharyngeal colonization with penicillin-resistant Streptococcus pneumoniae in Turkish children

BACKGROUND

Streptococcus pneumoniae is one of the major infectious agents observed in children. In spite of the fact that penicillin is preferred in the treatment of infections caused by S. pneumoniae, there has been a world-wide increase in the frequency of penicillin-resistant S. pneumoniae.

METHODS

One hundred and fifty sick children with a clinical diagnosis of pneumonia, meningitis, acute otitis media, acute sinusitis and septicemia or bacteremia, and 150 healthy children without any infection were examined. Streptococcus pneumoniae, which were isolated from the nasopharynx, were analyzed with respect to penicillin susceptibility using the agar dilution method.

RESULTS

The S. pneumoniae carriage rate was observed to be 43.3% in the group of sick children and 30.0% in the control group (P < 0.05). The penicillin resistance of S. pneumoniae isolated from the nasopharynx was determined to be 35.4% from a total of 110 isolates, with an intermediate resistance of 32.7% and a high resistance of 2.7%. The penicillin resistance of S. pneumoniae carried in the nasopharynx was determined to be 41.5% in the group of sick children and 26.6% in the control group (P > 0.05). Resistance rates of other antibiotics were determined as follows: cefotaxime 2.7%, erythromycin 19%, clarithromycin 5.4%, tetracycline 21.8%, trimethoprim-sulfamethoxazole 4.5% and rifampin 0%.

CONCLUSIONS

Penicillin resistance of S. pneumoniae has recently become a problem in Turkey. Because of this, we require new strategies to limit the spread of drug-resistant S. pneumoniae.

Evaluation of the PASCO strep plus broth microdilution antimicrobial susceptibility panels for testing Streptococcus pneumoniae and other Streptococcal species

Antimicrobial resistance continues to increase worldwide among isolates of Streptococcus pneumoniae and other species of streptococci. Increasing rates of penicillin resistance, particularly in viridans group streptococci, and resistance to multiple classes of antimicrobial agents, including beta-lactams, macrolides, and fluoroquinolones, in pneumococci have increased the importance of having accurate antimicrobial susceptibility testing results for guiding therapy. One commercial method of assessing resistance in streptococci is the PASCO Strep Plus panel. This broth microdilution-based method has recently been expanded to include a variety of newer antimicrobial agents. Therefore, we compared the results of the new PASCO Strep Plus panels for 26 antimicrobial agents against the results generated using the National Committee for Clinical Laboratory Standards (NCCLS) broth microdilution reference method for 75 pneumococci and 68 other streptococcal isolates. Only 4 (0.2%) very major errors (all with pneumococci and each with a different antimicrobial agent) were observed. There were 5 (0.3%) major errors observed with pneumococci (each with a different antimicrobial agent), but only 1 major error with nonpneumococcal streptococci. All of the very major and major errors resolved on retesting. Of the 65 (3.9%) and 17 (1.6%) minor errors observed with pneumococci and other streptococci, respectively, all were within 1 dilution of the broth microdilution reference MIC result. Thus, the PASCO Strep Plus panel has comparable accuracy to the NCCLS broth microdilution reference method.

Pneumococcal bacteremia during a decade in children in Soweto, South Africa

OBJECTIVES

To monitor for a decade the incidence and the clinical and microbiologic characteristics of pneumococcal bacteremia in children in Soweto and to assess the influence of HIV infection on any changes.

METHODS

Case records of children with pneumococcal bacteremia at Chris Hani Baragwanath Hospital from July, 1986, to June, 1987 (1986/ 1987), and from July, 1996, to June, 1997 (1996/ 1997), were retrospectively reviewed.

RESULTS

There were 194 episodes, 62 in 19861 1987 and 132 in 1996/1997. The minimum annual incidence for children younger than 5 years of age increased from 61 per 100000 (179 per 100000 for those <12 months old) in 1986/1987 to 130 per 100000 (349 per 100000 for those <12 months old) in 1996/1997. Sixty-seven (60%) of 111 patients tested in 1996/1997 were HIV-seropositive; none were tested in 1986/1987. The HIV-infected compared with HIV-noninfected were more likely to be malnourished (61% vs. 36%, P = 0.02), less likely to have other underlying disease (12% vs. 50%, P = 0.00001) and more frequently used antibiotics recently (69% vs. 43%, P = 0.008). Penicillin-nonsusceptible isolates were found in 22 (35%) patients in 1986/1987 and 52 (39%) in 1996/1997. There was no significant change in antimicrobial susceptibility during the decade or by HIV serostatus.

CONCLUSIONS

Children in Soweto had a high incidence of pneumococcal bacteremia which doubled during the decade mainly as a result of the impact of the HIV epidemic. There has been no significant change in antimicrobial susceptibility for the decade.

[Problems with gram-positive bacteria: resistance in staphylococci, enterococci, and pneumococci to antimicrobial drugs]

The resistance in staphylococci, enterococci, and pneumococci is reviewed. The author also recalls the first cases, and presents an overview of the distribution of cases in the world, the genetic and molecular mechanisms of resistance, the importance in Brazil and therapeutic alternatives. The factors that contribute to the dissemination of these problem bacteria and the measures for their control are emphasized.

Predictive value of pneumococcal nasopharyngeal cultures for the assessment of nonresponsive acute otitis media in children

BACKGROUND

Nonresponsive acute otitis media (NR-AOM) is reported in > 10% of children with AOM treated with antibiotics. Drug-resistant Streptococcus pneumoniae is currently considered the leading cause of antibiotic failures in AOM. Nasopharyngeal colonization with S. pneumoniae was found to increase significantly during episodes of AOM.

OBJECTIVES

To investigate the nasopharyngeal colonization with S. pneumoniae during NR-AOM and compare it with that found in AOM not recently treated with antibiotics (NT-AOM); to assess the predictive value of nasopharyngeal pneumococcal cultures results for the bacteriologic assessment of NR-AOM.

MATERIALS AND METHODS

Patients age 3 to 48 months with NT-AOM and NR-AOM were prospectively studied. Simultaneous nasopharyngeal cultures for S. pneumoniae and middle ear fluid cultures were obtained at enrollment. Antibiotic susceptibility testing was performed in all S. pneumoniae isolates. Penicillin and ceftriaxone MICs for S. pneumoniae were determined by E-test. The sensitivity, specificity and positive and negative predictive values of positive or negative nasopharyngeal cultures for the presence of S. pneumoniae in middle ear fluid were calculated.

RESULTS

We studied 362 and 217 children with NT-AOM and NR-AOM, respectively. Of the children with NT-AOM and NR-AOM, 95 and 97%, respectively, were younger than 2 years of age. S. pneumoniae was isolated in the nasopharynx of 66 and 58% of children with NT-AOM and NR-AOM, respectively. Penicillin-nonsusceptible S. pneumoniae was isolated more frequently from the nasopharynx of patients with NR-AOM than from those with NT-AOM (84% vs. 47%; P < 0.01). Antibiotic susceptibility patterns were similar for S. pneumoniae isolates recovered from the nasopharynx and those from the middle ear fluid in both NT-AOM and NR-AOM. A positive nasopharyngeal culture had only little predictive value for the presence of S. pneumoniae in middle ear fluid (41 and 51% for NT-AOM and NR-AOM, respectively). However, the negative predictive value of nasopharyngeal cultures for recovery of S. pneumoniae in NR-AOM was high and significantly higher in NR-AOM than in NT-AOM (91% vs. 78%, respectively; P = 0.009). The negative predictive value of nasopharyngeal cultures for recovery of antibiotic-resistant S. pneumoniae was 95 and 93% in NT-AOM and NR-AOM, respectively. Conclusions. A significantly higher nasopharyngeal colonization rate with antibiotic-resistant S. pneumoniae was found in patients with NR-AOM than in those with NT-AOM. Negative nasopharyngeal culture for antibiotic-resistant S. pneumoniae practically rules out its presence in middle ear fluid.

Impact of antibiotic resistance on chemotherapy for pneumococcal infections

Over the past three decades, penicillin-resistant pneumococci have emerged worldwide. In addition, penicillin-resistant strains have also decreased susceptibility to other beta-lactams (including cephalosporins) and these strains are often resistant to other antibiotic groups, making the treatment options much more difficult. Nevertheless, the present in vitro definitions of resistance to penicillin and cephalosporins in pneumococci could not be appropriated for all types of pneumococcal infections. Thus, current levels of resistance to penicillin and cephalosporin seem to have little, if any, clinical relevance in nonmeningeal infections (e.g., pneumonia or bacteremia). On the contrary, numerous clinical failures have been reported in patients with pneumococcal meningitis caused by strains with MICs > or = 0.12 microg/ml, and penicillin should never be used in pneumococcal meningitis except when the strain is known to be fully susceptible to this drug. Today, therapy for pneumococcal meningitis should mainly be selected on the basis of susceptibility to cephalosporins, and most patients may currently be treated with high-dose cefotaxime (+/-) vancomycin, depending on the levels of resistance in the patient's geographic area. In this review, we present a practical approach, based on current levels of antibiotic resistance, for treating the most prevalent pneumococcal infections. However, it should be emphasized that the most appropriate antibiotic therapy for infections caused by resistant pneumococci remains controversial, and comparative, randomized studies are urgently needed to clarify the best antibiotic therapy for these infections.

Occult bacteremia in young febrile children

The evaluation of nontoxic-appearing, young, febrile children has been a subject of considerable debate. Of young, nontoxic-appearing children aged 3 to 36 months with temperatures of 39 degrees C or more and no clear source, approximately 2% to 3% have occult bacteremia. Of these bacteremias, approximately 90% are caused by S. pneumoniae, 5% by nontyphoidal Salmonella sp., and 1% by N. meningitidis. Most children with occult pneumococcal bacteremia improve spontaneously, but approximately 25% of untreated patients have persistent bacteremia or develop new focal infections, including 3% to 6% who develop meningitis. Occult meningococcal bacteremia, although rare, has frequent complications, including meningitis in approximately 40% and death in approximately 4%. Less is known about the natural history of untreated occult nontyphoidal Salmonella bacteremia. Empiric antibiotic treatment of children with occult bacteremia decreases the rate of complications, including meningitis. Few disagree that febrile, young children at risk for occult bacteremia require a careful clinical evaluation and close follow-up. The benefits of laboratory screening and selective empiric antibiotic treatment of febrile children at risk for occult bacteremia have to be weighed against the costs of screening tests and blood cultures, inconvenience, temporary discomfort to patients, risk for side effects of antibiotics, and the role of antibiotics in the development of bacterial resistance. Although great debate exists concerning the role of empiric antibiotics, a strategy for obtaining blood cultures and empirically administering antibiotics on the basis of an increased ANC, in addition to close clinical follow-up, may be effective in reducing the frequency and severity of uncommon but adverse sequelae. A highly effective S. pneumoniae bacterial conjugate vaccine will soon be available, which will benefit all children, and will alter the ways that clinicians evaluate fully immunized young, febrile children.

Nasopharyngeal carriage of multidrug-resistant Streptococcus pneumoniae in institutionalized HIV-infected and HIV-negative children in northeastern Romania

OBJECTIVES

The study compared nasopharyngeal carriage of resistant pneumoniae in human immunodeficiency virus (HIV)-seropositive and -seronegative children.

METHODS

Nasopharyngeal colonization with Streptococcus pneumoniae was investigated during May 1996 in 162 HIV-negative infants and children (age range, 1-38 mo) and 40 HIV-infected children (age range, 39-106 mo) living in an orphanage in Iasi, northeastern Romania. The HIV-infected children lived separated from the other children and were cared for by a different staff. Streptococcus pneumoniae was isolated from 12 of 40 (30%) HIV-infected and from 81 of 160 (50%) HIV-negative children. Antimicrobial susceptibility to penicillin and ceftriaxone was determined by E-test, and to another five antibiotics by disk diffusion. Serotyping was performed by the Quellung method on 81 of 93 (87%) isolates.

RESULTS

Serotypes 6A, 6B, 19A, and 23F together represented 98% of all isolates. Ninety-nine percent of S. pneumoniae isolates were resistant to penicillin, and 74% were highly resistant to penicillin (minimum inhibitory concentration [MIC] > 1 mg/mL); MIC50 and MIC90 to penicillin of the isolates were 2 mg/mL and 8 mg/mL, respectively. Eighty-nine of ninety-one isolates were susceptible to ceftriaxone; 99%, 87%, 87%, 48%, and 21% of the isolates were resistant to trimethoprim-sulphamethoxazole, erythromycin, clindamycin, tetracycline, and chloramphenicol, respectively. Eighty-two (89%) isolates were multidrug resistant (resistant to =/>3 antibiotic classes); 37 of 92 (40%) isolates were resistant to 5 or more antibiotic classes, and 16 of these 37 (43%) belonged to serotype 19A. All serotype 19 isolates were highly resistant to penicillin.

CONCLUSIONS

No significant differences were observed in the resistance rates of S. pneumoniae in HIV-infected children compared to HIV-negative children. Multidrug-resistant pneumococci were highly prevalent in this Romanian orphanage in both HIV-negative and older HIV-infected children. The observed high prevalence of multidrug-resistant pneumococci (coupled with high penicillin resistance) with a limited number of circulating serotypes emphasizes the need to further evaluate the conjugate vaccines in children at risk for invasive pneumococcal infection.

In vitro activity and pharmacodynamics of oral beta-lactam antibiotics against Streptococcus pneumoniae from southeast Missouri

STUDY OBJECTIVES

To determine the frequency of reduced susceptibility to penicillin, and to compare the in vitro activity and pharmacodynamics of oral beta-lactam antibiotics against clinical isolates of Streptococcus pneumoniae from southeast Missouri.

SETTING

Cape Girardeau, Missouri (population 35,500). Interventions. Minimum inhibitory concentrations (MICs) were determined for penicillin, amoxicillin, amoxicillin-clavulanic acid, cefprozil, cefuroxime, cefpodoxime, cefaclor, and loracarbef by E test for 108 isolates of S. pneumoniae. The MIC50, MIC90, and percentage susceptibility were calculated for each agent. Pharmacokinetic variables were obtained from the literature, and serum concentration-time profiles were simulated for a 25-kg child taking pediatric dosages commonly administered to treat otitis media. The average time above MIC (T > MIC) was calculated as percentage of the dosing interval using free concentrations and the MIC for each individual isolate. Analysis of variance (Scheffe post hoc test) was used to determine differences among agents for in vitro activity and T > MIC (level of significance, p<0.05).

MEASUREMENTS AND MAIN RESULTS

The frequency of penicillin-nonsusceptible S. pneumoniae was 28.7% (31/108). For 25 penicillin-intermediate isolates, amoxicillin and amoxicillin-clavulanic acid were significantly more active than cefprozil, cefaclor, and loracarbef. The T > MIC for amoxicillin and amoxicillin-clavulanic acid, simulated at 13.3 mg/kg every 8 hours, was significantly longer than that for all other beta-lactams.

CONCLUSION

Amoxicillin and amoxicillin-clavulanic acid have superior in vitro activity and longer T > MIC for penicillin-intermediate isolates than the other oral beta-lactams.

Five day moxifloxacin therapy compared with 7 day clarithromycin therapy for the treatment of acute exacerbations of chronic bronchitis

In this multinational, randomized, double-blind study, the efficacy and safety of a 5 day course of moxifloxacin 400 mg orally od was compared with that of a 7 day course of clarithromycin 500 mg orally bd. in 750 patients with acute exacerbations of chronic bronchitis, characterized by at least two of the symptoms: sputum purulence, increased sputum volume or increased dyspnoea. Seven days after the end of therapy, clinical cure was achieved for 89% (287 of 322) of efficacy-evaluable patients in the moxifloxacin group and 88% (289 of 327) of patients in the clarithromycin group (95% CI, -3.9%, 5.8%). At follow-up (21-28 days post-treatment), the continued clinical cure rates were 89% (256 of 287) for moxifloxacin and 89% (257 of 289) for clarithromycin. A total of 342 pathogenic bacteria were isolated from the sputum of 287 patients. The most common pathogens were Haemophilus influenzae (37%), Streptococcus pneumoniae (31%) and Moraxella catarrhalis (18%). Seven days post-treatment, a successful bacteriological response was obtained for 77% (89 of 115) of patients in the moxifloxacin group and 62% (71 of 114) of patients in the clarithromycin group, indicating superiority of moxifloxacin (95% CI, 3.6%, 26.9%). Both treatments were well tolerated with few adverse events. This study demonstrated that for the treatment of acute exacerbations of chronic bronchitis a 5 day course of moxifloxacin 400 mg od was clinically equivalent and bacteriologically superior to a 7 day course of clarithromycin 500 mg bd.

Bacteremic pneumococcal pneumonia in one American City: a 20-year longitudinal study, 1978-1997

A surveillance of bacteremic pneumococcal pneumonia was conducted in Huntington, West Virginia, from 1978 to 1997 to investigate case-fatality rates, incidence of disease, capsular types, and antibiotic usage. Our study population comprised consecutive inpatients admitted to the hospitals in Huntington, West Virginia, and included 45 children younger than 15 years and 328 adults. All blood isolates were serotyped by capsular swelling procedures; clinical characteristics, treatment, and outcome for all patients were abstracted from hospital charts. The overall case-fatality rate was 20.3%, with most deaths occurring among adults older than 50 years. Case-fatality rates peaked at 37.7% among patients 80 years of age and older. Only 1 of 45 (2.2%) children died. Case-fatality rates declined in each successive 5-year period, from 30.2% in 1978-1982 to 15.6% in 1993-1997. In that same period, incidence rates increased severalfold among children younger than 4 years to 44.5 cases per 100,000 population and among adults 70 years and 80 years of age and older to 38.5 and 76.2 cases per 100,000, respectively. Of the 34 serotypes isolated, 10 accounted for two thirds of the cases of pneumonia: 1, 4, 9, 14, 3, 6, 12, 5, 23, and 19 (in rank order). Chronic renal disease and arteriosclerotic heart disease increased the risk of death. Treatment regimens that included a macrolide and a penicillin or cephalosporin resulted in the lowest case-fatality rate in adults older than 50 years: 6% in 1993-1997. In conclusion, as bacteremic pneumococcal pneumonia evolved over time, the case-fatality rate decreased, its incidence increased, predominant capsular types changed, and treatment regimens that included a macrolide resulted in the lowest fatality rates.

Documentation of the prevalence of penicillin-resistant Streptococcus pneumoniae isolated from the middle ear and sinus fluid of children undergoing tympanocentesis or sinus lavage

With increasing pneumococcal resistance to penicillin and other antibiotics, use of antibiotic therapy for children with upper respiratory tract infections such as otitis media and sinusitis has become difficult. Selecting an appropriate treatment regimen has become more challenging due to frequent concomitant microbial resistance to multiple antibiotics. In a prospective, nonrandomized study, we obtained middle ear and sinus aspirate specimens from all children undergoing outpatient tympanocentesis or sinus lavage for any indication at our institution over two 4-week periods. One hundred fifty-four specimens were obtained. Of these, 12 grew Streptococcus pneumoniae, 7 of which were resistant to penicillin. A 6-month retrospective review of these patients' medical histories evaluated their antibiotic use prior to surgical intervention. An association between penicillin resistance and recent use of 2 or more antibiotics in children with positive S pneumoniae cultures was confirmed, as has been documented in prior reports. Those with penicillin-resistant S pneumoniae also demonstrated a higher incidence of multidrug-resistant organisms.

Drug-resistant Streptococcus pneumoniae: rational antibiotic choices

Increasingly, Streptococcus pneumoniae with reduced susceptibility to penicillin is becoming a healthcare concern, not only because of the high prevalence of infections caused by this pathogen but also because of the rate at which resistance has progressed. The incidence of penicillin resistance in strains of S. pneumoniae approaches 40% in some areas of the United States, and the incidence of high-level resistance has increased by 60-fold during the past 10 years. With the exception of meningitis and otitis media, there is no conclusive evidence that the acquisition of resistance by S. pneumoniae to beta-lactam antibiotics incurs greater morbidity and mortality in infections caused by this pathogen. However, if the current trends of resistance patterns continue, one can expect the morbidity and mortality to increase. The mechanism of beta-lactam resistance of S. pneumoniae involves genetic mutations which alter penicillin-binding protein structure, resulting in a decreased affinity for all beta-lactam antibiotics. In the treatment of infections caused by S. pneumoniae, it should not be assumed that nonsusceptibility to beta-lactam antibiotics correlates with clinical ineffectiveness of these agents. On the contrary, the recommended therapy for nonmeningeal pneumococcal infections (e.g., pneumonia, sepsis, acute otitis media) includes a beta-lactam antibiotic: penicillin G, amoxicillin, amoxicillin/clavulanate, cefuroxime, cefotaxime, or ceftriaxone. Recommended therapy for meningitis is cefotaxime or ceftriaxone, with the addition of vancomycin until susceptibility is known. These agents are recommended because of their ability to achieve serum/tissue concentrations greater than the minimum inhibitory concentrations (MICs) of these agents against penicillin-susceptible, penicillin-intermediate, and most penicillin-resistant strains (e.g., penicillin G, cefotaxime, ceftriaxone, amoxicillin, amoxicillin/clavulanate, and cefuroxime), or their ability to provide adequate concentrations in cerebrospinal fluid (e.g., cefotaxime, ceftriaxone).