Rapid emergence of penicillin-resistant pneumococci in Hong Kong

Antibiotics prescribing practices in oral implantology among jordanian dentists. A cross sectional, observational study

BACKGROUND

In oral implantology, there is no consensus on the most appropriate regimen for antibiotics prescribing, the decision to prescribe antibiotic is usually based on procedure, patient and clinician related factors. The aim of this study was to investigate the rationale of antibiotic prescribing among Jordanian clinicians who practice oral implantology.

FINDINGS

The target sample for the study was the 250 Jordan Dental Implant Group members. A five page questionnaire contained 41 questions, both closed and open questions were used to collect data. Statistical analysis was performed using SPSS Windows 16.0 (SPSS Inc., Chicago, IL, USA). Descriptive statistics were generated.The response rate was (70.4%) 176/250. Mean age was 37.2 yrs, 49.4% always prescribe antibiotics mainly oral amoxicillin and amoxicillin with clavulinic acid. Antibiotics prescribing increased with flap raising, multiple implants and sinus or bone augmentation. Patient medical condition, periodontitis and oral hygiene were the most important clinical factors in antibiotic prescribing, non-clinical factors were; reading scientific materials, courses and lectures, knowledge gained during training, and the effectiveness and previous experience with the drug.

CONCLUSIONS

Wide variations in antibiotics types, routes, dose and duration of administration were found. Recommendations on antibiotic prescribing are needed to prevent antibiotic overprescribing and misuse.

Adult Streptococcus pneumoniae meningitis in Southern Taiwan: epidemiologic trends and prognostic factors

The clinical features of 22 adult patients with Streptococcus pneumoniae meningitis, retrospectively collected over a 16-year period, were reviewed. Otopharyngeal infection, haematogenous spread and cranial neurosurgery continue to be the predominant routes of infection. Most patients acquired the infection in the community, and predisposing underlying conditions are common. The proportion of S. pneumoniae meningitis compared to all microorganisms causing meningitis in adults declined dramatically from 17% in the first 8 study years to 4% in the last 8 study years. However, all penicillin-resistant S. pneumoniae strains were found in the second half of the study period, accounting for 25% of these episodes. The overall mortality rates for the first and second halves of the study period were 43% and 63%, respectively. Third-generation cephalosporins were the antibiotics of choice for the treatment of S. pneumoniae meningitis in this study, however, the emergence of resistant strains may create a therapeutic challenge in the future. To avoid treatment failure, early diagnosis, careful monitoring of the clinical course and the choice of appropriate antibiotics according to the in vitro antimicrobial susceptibilities, are necessary.

Beta-lactam and macrolide resistance and serotype distribution among Streptococcus pneumoniae isolates from Saudi Arabia

Three hundred thirty-six clinically significant Streptococcus pneumoniae isolates were collected from laboratories of different hospitals in Riyadh, Saudi Arabia. Most of these isolates were from pulmonary and otitis media (68.2%), and 31.8% were extrapulmonary (blood and CSF). Of the 336 isolates, 44.6% were susceptible to penicillin, and 55.4% were penicillin non-susceptible (35.7% were intermediate and 19.7% were fully resistant). The isolates showed 9.0% resistance to co-amoxiclav, 31.8% to cefuroxime and 39.4% to cefprozil. None of the isolates were resistant to ceftriaxone. Overall macrolide resistance rates were 22.6% to erythromycin, 18.5% to roxithromycin, 17.9% to azithromycin and 17.3% to clarithromycin. Most penicillin non-susceptible pneumococci were of serogroups/types 19 (21.0%), 6 (10.8%), 18 (8.6%), 23 (8.1%) and 14 (7.0%). Serogroups 9, 15, and 1 were found in 5.4%, 4.3%, and 2.2% of the isolates, respectively. Nontypeable strains constituted 6.5%. In exploring the mechanism of resistance to macrolides, 28 of 76 (36.8%) of isolates were erythromycin-resistant due to ribosomal mechanism (all were constitutive type, none were inducible), whereas 48 (63.2%) isolates were resistant due to an efflux mechanism. Good antibiotic control with periodical antibiotic surveillance and appropriate use of pneumococcal vaccine may improve current treatment of pneumococcal infections.

Emergence in Vietnam of Streptococcus pneumoniae resistant to multiple antimicrobial agents as a result of dissemination of the multiresistant Spain(23F)-1 clone

Surveillance for Streptococcus pneumoniae resistant to penicillin and other antimicrobial agents is necessary to define the optimal empirical antibiotic therapy for meningitis in resource-poor countries such as Vietnam. The clinical and microbiological features of 100 patients admitted to the Centre for Tropical Diseases in Ho Chi Minh City, Vietnam, between 1993 and 2002 with invasive pneumococcal disease were studied. A penicillin-nonsusceptible pneumococcus (MIC, > or =0.1 micro g/ml) was isolated from the blood or cerebrospinal fluid of 8% of patients (2 of 24) between 1993 and 1995 but 56% (20 of 36) during 1999 to 2002 (P < 0.0001). Pneumococcal isolates resistant to penicillin (MIC, > or =2.0 micro g/ml) increased from 0% (0 of 24) to 28% (10 of 36) (P = 0.002). Only one isolate was ceftriaxone resistant (MIC, 2.0 micro g/ml). Penicillin-nonsusceptible pneumococci were isolated from 78% of children younger than 15 years (28 of 36) compared with 25% of adults (16 of 64) (P = 0.0001). Isolation of a penicillin-nonsusceptible pneumococcus in adults with meningitis was independently associated with referral from another hospital (P = 0.005) and previous antibiotic therapy (P = 0.025). Multilocus sequence typing showed that 86% of the invasive penicillin-resistant pneumococcus isolates tested (12 of 14) were of the Spain(23F)-1 clone. The serotypes of >95% of the penicillin-nonsusceptible pneumococci were included in the currently available pneumococcal vaccines. Our findings point to the recent introduction and spread of the Spain(23F)-1 clone of penicillin-resistant pneumococci in Vietnam. Simple clinical predictors can be used to guide empirical antibiotic therapy of meningitis. Pneumococcal vaccination may help to control this problem.

Prevalence of serotypes and molecular epidemiology of Streptococcus pneumoniae strains isolated from children in Beijing, China: identification of two novel multiply-resistant clones

Three-hundred and seventy-six strains of Streptococcus pneumoniae isolated from clinical specimens and nasopharyngeal swabs from children at daycare centers and hospitals in Beijing China, between January 1997 and March 1998, were serotyped. Twenty-seven different serotypes were identified. The most prevalent serotypes in the carriage isolates were 6A, 19F, 23F, and 15 and were found in 66.8% of cases. Serotype data indicate that 51.8% of carrier strains would be included in the 11-valent conjugate vaccine formulation, while inclusion of vaccine-related serotypes, increased the potential vaccine coverage to 79.4%. Serotypes 7, 6B, 23F, 19F, 15, and 3 accounted for 62% of clinical strains, with 70% vaccine-related serotypes. DNA fingerprinting of 47 penicillin resistant and 71 penicillin-susceptible/macrolide-resistant strains by BOX polymerase chain reaction (PCR), pulsed-field gel electrophoresis (PFGE), and penicillin binding protein (PBP)-fingerprinting identified two novel clones: one a serotype 23F multiresistant clone resistant to penicillin, tetracycline, erythromycin, clindamycin, and variably resistant to chloramphenicol and trimethoprim-sulphamethoxazole; and the second a multiresistant penicillin-susceptible, macrolide-resistant serotype 6A clone, highly resistant also to tetracycline, clindamycin, and trimethoprim-sulphamethoxazole. The macrolide resistance determinant in 89% of erythromycin-resistant strains tested (penicillin-susceptible and penicillin-resistant) was the erm gene, both the erm and mef genes were simultaneously found in 6%, and mef alone in 3.4%. The data demonstrates that macrolide resistant strains in China include clonal strains and strains with dual mef and erm resistance determinants.

Nasal carriage in Vietnamese children of Streptococcus pneumoniae resistant to multiple antimicrobial agents

Resistance to antimicrobial agents in Streptococcus pneumoniae is increasing rapidly in many Asian countries. There is little recent information concerning resistance levels in Vietnam. A prospective study of pneumococcal carriage in 911 urban and rural Vietnamese children, of whom 44% were nasal carriers, was performed. Carriage was more common in children <5 years old than in those >/=5 years old (192 of 389 [49.4%] versus 212 of 522 [40.6%]; P, 0.01). A total of 136 of 399 isolates (34%) had intermediate susceptibility to penicillin (MIC, 0.1 to 1 mg/liter), and 76 of 399 isolates (19%) showed resistance (MIC, >1.0 mg/liter). A total of 54 of 399 isolates (13%) had intermediate susceptibility to ceftriaxone, and 3 of 399 isolates (1%) were resistant. Penicillin resistance was 21.7 (95% confidence interval, 7.0 to 67.6) times more common in urban than in rural children (35 versus 2%; P, <0.001). More than 40% of isolates from urban children were also resistant to erythromycin, trimethoprim-sulfamethoxazole, chloramphenicol, and tetracycline. Penicillin resistance was independently associated with an urban location when the age of the child was controlled for. Multidrug resistance (resistance to three or more antimicrobial agent groups) was present in 32% of isolates overall but in 39% of isolates with intermediate susceptibility to penicillin and 86% of isolates with penicillin resistance. The predominant serotypes of the S. pneumoniae isolates were 19, 23, 14, 6, and 18. Almost half of the penicillin-resistant isolates serotyped were serotype 23, and these isolates were often multidrug resistant. This study suggests that resistance to penicillin and other antimicrobial agents is common in carriage isolates of S. pneumoniae from children in Vietnam.

Evidence of clonal dissemination of multidrug-resistant Streptococcus pneumoniae in Hong Kong

The relationship between the phenotypic and genotypic characteristics of 105 penicillin-intermediate or -resistant Streptococcus pneumoniae isolates saved during 1994 to 1997 at the Prince of Wales Hospital and Pamela Youde Nethersole Eastern Hospital, Hong Kong, was studied. The pbp genes for penicillin-binding proteins 1a, 2b, and 2x for each isolate were amplified by PCR, and the products were digested with restriction enzymes HinfI and AluI. A combination of the pulsed-field gel electrophoresis (PFGE) profiles, pbp fingerprints, and phenotypic characteristics of capsular types and antibiograms enabled these isolates to be divided into four major groups. Seventy-four percent (78 of 105) of the strains, belonging to serotypes 23F, 19F, and 14, showed indistinguishable pbp fingerprint patterns (group A1, 1-1-1, 1-1-1), with PFGE patterns belonging to group A and its subtypes, suggesting that these strains were closely related. Eighty-three percent (65 of 78) of these isolates were also resistant to tetracycline, erythromycin, chloramphenicol, and trimethoprim. The type 23F isolates were indistinguishable from representative strains of the Spanish 23F clone by these molecular methods, indicating that these strains may be variants of the Spanish 23F clone. Serotype 6B accounted for 19% (20 of 105) of the isolates with reduced penicillin susceptibility and was made up of variants belonging to four different pbp fingerprint groups with the PFGE pattern group B, the predominant group being indistinguishable from that of the Spanish 6B clone. Other PFGE and fingerprint groups were mainly obtained from penicillin-susceptible strains of various serotypes. The results suggest that the rapid emergence of drug-resistant S. pneumoniae in Hong Kong has been due to the rapid dissemination of several successful clones.

Therapy for pneumococcal infection at the millennium: doubts and certainties

Rapidly burgeoning worldwide multiple drug-resistant pneumococcal serotypes pose an urgent demand for new management approaches. Perhaps modern intensive care methods may have alternatives to offer. Indeed, standard assessments such as the admission APACHE II score may overestimate individual risk of death in severe CAP, and mortality can be reduced. However, among those at highest risk for mortality in the early phase of invasive disease, the conclusions reached 2-3 decades ago, that it is questionable whether a more effective drug than penicillin can be developed, and that a reduction in the number of deaths consequent to this infection can be accomplished only by widespread immunoprophylactic measures, remain inescapable. Clearly, as discussed elsewhere in this supplement, the continuing validity of these 20-year-old conclusions and the global prevalence of DRSP demand the development and marketing of new conjugate vaccines, although more widespread use of the existing 23-valent polysaccharide vaccine among high-risk populations is essential in the interim. With respect to resistance selection pressures, antibiotic prescription control may provide the answer. However, patient expectations of antibiotic therapy for trivial respiratory infection is high and, in the United Kingdom, 75% of previously healthy adults will receive it; those who do not will usually consult another physician in an effort to secure such therapy. Thus, without the intervention of government or managed care organizations, self-regulation in prescribing is unlikely. The evidence for beta-lactam treatment failure in meningitis has led to alternative approaches, with vancomycin as the primary agent. Penicillins may remain effective for otitis media, but oral cephalosporins are suspect. Data on pediatric pneumococcal pneumonia continue to suggest use of beta-lactams, at least for disease caused by strains with intermediate penicillin sensitivity. Pallares et al concluded that penicillins and cephalosporins remain the drugs of choice for severe pneumococcal pneumonia in adults. Others who share this conclusion often cite that study as evidence. However, in the case of penicillins, the mortality rate was 6% higher in a subgroup selected for monomicrobial infection and reduced risk factors for mortality when penicillin-resistant infection was present, and the overall mortality was 14% higher with penicillin-resistant strains (taking into account "all comers"). Those who depend on the findings of evidence-based medicine may accept the premise that penicillins and cephalosporins remain the drugs of choice, and agree with Goldstein and Garau that it would indeed be a mistake to adopt alternative therapies. Others may consider the deaths of 6 of 100 patients who were not in the highest-risk group too high a price to pay for statistical significance and may be skeptical of the continued use of beta-lactam therapy on higher-risk patients. In addition, the persistent selection pressure applied by continued use of beta-lactams offers a powerful population-based argument for alternatives. As DRSP continues to spread and resistant strains with penicillin MIC >2 mg/L become more prevalent, new agents such as the azabicyclo-methoxyquinolone, moxifloxacin, and perhaps grepafloxacin, but not the more toxic sparfloxacin and trovafloxacin, will undoubtedly flourish as treatments for CAP. By that time, the results of clinical studies on ketolides and oxazolidinones could offer further choices.

Extremely high incidence of macrolide and trimethoprim-sulfamethoxazole resistance among clinical isolates of Streptococcus pneumoniae in Taiwan

From January 1996 to December 1997, 200 isolates of Streptococcus pneumoniae recovered from 200 patients treated at National Taiwan University Hospital were serotyped and their susceptibilities to 16 antimicrobial agents were determined by the agar dilution method. Sixty-one percent of the isolates were nonsusceptible to penicillin, exhibiting either intermediate resistance (28%) or high-level resistance (33%). About two-fifths of the isolates displayed intermediate or high-level resistance to cefotaxime, ceftriaxone, cefepime, imipenem, and meropenem. Extremely high proportions of the isolates were resistant to erythromycin (82%), clarithromycin (90%), and trimethoprim-sulfamethoxazole (TMP-SMZ) (87%). Among the isolates nonsusceptible to penicillin, 23.8% were resistant to imipenem; more than 60% displayed resistance to cefotaxime, ceftriaxone, cefepime, and carbapenems; 96.7% were resistant to erythromycin; and 100% were resistant to TMP-SMZ. All isolates were susceptible to rifampin and vancomycin. The MICs at which 50% and 90% of the isolates were inhibited were 0.12 and 1 microgram/ml, respectively, for cefpirome, and 0.12 and 0.25 microgram/ml, respectively, for moxifloxacin. Six serogroups or serotypes (23F, 19F, 6B, 14, 3, and 9) accounted for 77.5% of all isolates. Overall, 92.5% of the isolates were included in the serogroups or serotypes represented in the 23-valent pneumococcal vaccine. The incidence of macrolide and TMP-SMZ resistance for S. pneumoniae isolates in Taiwan in this study is among the highest in the world published to date.

Identification of three major clones of multiply antibiotic-resistant Streptococcus pneumoniae in Taiwanese hospitals by multilocus sequence typing

In this paper we demonstrate the advantages of a new molecular typing procedure, multilocus sequence typing, for the unambiguous characterization of penicillin-resistant pneumococci. The sequences of approximately 450-bp fragments of seven housekeeping genes were determined for 74 penicillin-resistant Taiwanese isolates of Streptococcus pneumoniae (MIC of penicillin > 0.5 microgram/ml). The combination of alleles at the seven loci defined an allelic profile for each strain, and a dendrogram, based on the pairwise mismatches in allelic profiles, grouped 86% of the isolates into one of three penicillin-resistant clones for which the MICs of penicillin were 1 to 2 microgram/ml. Isolates within each clone had identical alleles at all seven loci or differed at only a single locus, and the fingerprints of their pbp1A, pbp2B, and pbp2X genes were uniform. Isolates of the Taiwan-19F clone and the Taiwan-23F clone were resistant to penicillin, tetracycline, and erythromycin but were susceptible to chloramphenicol. A second serotype 23F clone and serotype 19F variants of this clone were resistant to penicillin, tetracycline, chloramphenicol, and, in some cases, erythromycin. Comparisons of the allelic profiles of the three major clones with those of reference isolates of the known penicillin-resistant clones showed that the Taiwan-19F and Taiwan-23F clones were previously undescribed, whereas the second serotype 23F clone was indistinguishable from the Spanish multidrug-resistant serotype 23F clone. Single isolates of the Spanish penicillin-resistant serotype 9V clone and the Spanish multidrug-resistant serotype 6B clone were also identified in the collection.

The ethnic minority traveler

Although the ethnic minority traveler is exposed to the same risks as other travelers, there are special considerations that make them vulnerable to certain diseases. In addition, many ethnic minority travelers are traditionally underserved by the medical community and often travel without the benefit of adequate counseling and immunization. The specific disease entities covered in this article include parasitic diseases (e.g. malaria, trypanosomiasis, intestinal helminths), tuberculosis, and other respiratory diseases, dengue, and sexually transmitted diseases and HIV.

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.

Dental implant installation without antibiotic prophylaxis

The objective of this study was to retrospectively compare the outcomes of dental implant treatment with and without antibiotic prophylaxis. Two groups of patients with edentulous or partially edentulous maxillas or mandibles (or both) were treated with dental implants. One group, consisting of 147 patients (790 implants), was given prophylaxis with oral phenoxymethylpenicillin; 1 g of antibiotic was administered 1 hour preoperatively, and 1 g was administered every 8 hours for 10 days postoperatively. The other group, consisting of 132 patients (664 implants) was not given any antibiotics preoperatively or postoperatively. There were no significant differences with respect to early and late postoperative infections or with respect to implant survival between the two groups. It appears that antibiotic prophylaxis for routine dental implant surgery offers no advantage for the patient.

Comparison of E-test with agar dilution for determining susceptibility of Streptococcus pneumoniae to penicillin

Minimum inhibitory concentrations (MICs) of penicillin for Streptococcus pneumoniae were determined by the E-test and the agar dilution method. Ninety Streptococcus pneumoniae strains were tested, of which 16 were resistant, 33 intermediate, and 41 susceptible by agar dilution. By the E-test, 80 (88.9%) strains agreed with these determinations within one log2 dilution step, and no strains disagreed by more than two dilution steps. Sixty-eight of the 70 strains with discrepant MICs read lower in the E-test, resulting in 15 strains being placed in different susceptibility categories when classified by this test. Exact MICs rather than classification groups should be used to determine appropriate antibiotic therapy, since small differences in MICs determined by different methods can lead to a significant degree of misclassification.