Penicillin-resistant pneumococci

Serotype distribution and antibiotics susceptibility pattern of Streptococcus pneumonia in Iran

Background

The development of antibiotic resistance among Streptococcus pneumoniae strains has caused significant health problems worldwide.

Objectives

The aim of this study was to determine antibiotic resistance pattern and serotypes distribution of Streptococcus pneumoniae strains isolated from clinical specimens.

Material and Methods

A total of fifty Streptococcus pneumoniae strains were isolated from Tehran Hospital’s laboratory from 2008 to 2012. Antimicrobial susceptibility testing was performed using broth microdilution method and minimum inhibitory concentration (MIC) of each strain was determined. to verify the resistant strains and demonstrate the presence of antibiotic resistant genes, the PCR was performed.

Results

The study showed that three strains (6%) and six strains (12%) indicated intermediate resistance and complete resistance to penicillin, respectively, 58% strains were susceptible to ceftazidime, two ones (4%) indicated resistance to ciprofloxacin, one (2%) indicated intermediate resistance to ceftriaxone , two strains (4%) indicated complete resistance and four (8%) strains indicated resistance to vancomycin.

Conclusions

The emergence of Streptococcus pneumoniae strains with multiple resistance needs permanent monitoring of antibiotic susceptibility patterns of clinical isolates. We have found that ceftazidime is not a suitable drug for choosing the treatment of pneumococcal infections.

Efficacy and safety of oral gemifloxacin for the empirical treatment of pneumonia

CONTEXT

Respiratory tract infections (RTI) are common causes of morbidity and mortality worldwide. Initial antibiotic therapy in upper and lower respiratory tract infections is usually empirical. The increasing evidence of antibacterial resistance in the pathogens commonly associated with pneumonia has raised concerns about the efficacy of currently available therapies and poses a challenge to clinicians. Gemifloxacin is a synthetic fluoroquinolone antimicrobial agent exhibiting potent activity against most Gram negative and Gram positive organisms. Hence, this study was planned to evaluate the efficacy of gemifloxacin as an empirical therapy in pneumonia.

MATERIALS AND METHODS

This was an open labelled, single-arm study. Patients with clinical features of community acquired pneumonia (CAP) who fulfilled the inclusion criteria received treatment with oral gemifloxacin 320 mg once daily for 5-7 days. Once enrolled in the study, patients were treated as outpatient or as inpatient depending on clinical need. The primary efficacy was to evaluate the clinical response at the end of therapy, i.e., day 9-11 for CAP. Secondary efficacy parameters included radiological and bacteriological response at the end of therapy. Patients were evaluated three times during the entire course of treatment (Visit 1, Day 0; Visit 2, Day 2-4; Visit 3, Day 9-11) for their clinical, radiological and/or bacteriological response, as well as for safety assessment.

RESULTS

A total of 105 patients received the study medication (gemifloxacin 320 mg orally). Two patients were "lost to follow-up" and one patient had to discontinue medication due to insufficient therapeutic effects. Clinical response at the end of therapy was successful in 99 (96.1%) while clinical failure was reported in 4 (3.9%) patient. As per the radiological response, 77.1% of the total cases showed improvement, 8.6% had no change, and 2.9% cases had deterioration in radiological findings. Gemifloxacin is an effective drug in the management of CAP.

CONCLUSIONS

Gemifloxacin with coverage against both Gram positive and Gram negative organisms as well as atypical pathogens, with once daily oral dosing and minimum side effect is a very effective and economical choice for treating CAP empirically.

Finding a strategy: the case for co-operative research on resistance epidemiology

Progress on rational intervention to prevent increasing antibiotic resistance has been slow. We suggest that this is because the science of resistance epidemiology has received little attention, and that a systematic, co-operative investigation of this area might yield a relevant knowledge base, analogous to the basis for effective public health intervention in infectious disease given by infection epidemiology. The steps required to progress this approach in the UK are discussed, along with a summary of what is known and speculation on what might emerge.

Factors associated with penicillin-nonsusceptible pneumococcal infections in Brazil

Resistance of Streptococcus pneumoniae is a worldwide, growing problem. Studies of factors associated with resistance to penicillin have not been conducted in Brazil. The objective of the present study was to evaluate factors associated with infection by S. pneumoniae not susceptible to penicillin. A prevalence study was conducted including all patients with a positive culture for S. pneumoniae in a hospital from July 1991 to December 1992 and the year 1994. Of 165 patients identified, 139 were considered to have clinically relevant infections and 88% of them had invasive infections. All infections were community acquired and consisted of pneumonia (44%) and of central nervous system (19%), pelvic or abdominal (12%), upper airway or ocular (12%), primary bloodstream (9%) and skin and soft tissue (5%) infections. Mortality was 25%. Susceptibility to penicillin was present in 77.6% of the isolates; 21.8% were relatively resistant, and one isolate was resistant (minimal inhibitory concentration = 4 micro g/ml). Multivariate analysis showed that age below 4 years (odds ratio (OR): 3.53, 95% confidence interval (95%CI): 1.39-8.96) and renal failure (OR: 5.50, 95%CI: 1.07-28.36) were associated with lack of susceptibility to penicillin. Bacteremia occurred significantly less frequently in penicillin-nonsusceptible infections (OR: 0.34, 95%CI: 0.14-0.84), possibly suggesting that lack of penicillin susceptibility is associated with lower virulence in S. pneumoniae.

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.

Nomenclature of major antimicrobial-resistant clones of Streptococcus pneumoniae defined by the pneumococcal molecular epidemiology network

The emergence of disease caused by penicillin-resistant and multidrug-resistant pneumococci has become a global concern, necessitating the identification of the epidemiological spread of such strains. The Pneumococcal Molecular Epidemiology Network was established in 1997 under the auspices of the International Union of Microbiological Societies with the aim of characterizing, standardizing, naming, and classifying antimicrobial agent-resistant pneumococcal clones. Here we describe the nomenclature for 16 pneumococcal clones that have contributed to the increase in antimicrobial resistance worldwide. Guidelines for the recognition of these clones using molecular typing procedures (pulsed-field gel electrophoresis, BOX-PCR, and multilocus sequence typing) are presented, as are the penicillin-binding profiles and macrolide resistance determinants for the 16 clones. This network can serve as a prototype for the collaboration of scientists in identifying clones of important human pathogens and as a model for the development of other networks.

Effect of antimicrobial use and other risk factors on antimicrobial resistance in pneumococci

Penicillin-resistant and multi-resistant pneumococci have spread globally and reached high prevalence in many countries. Antimicrobial use is considered a major driving force for resistance, although the influence in the community has not been as clearly demonstrated. Other risk factors may be important, and only with a clear understanding of the risk factors can effective control measures be introduced. The main habitat of the pneumococcus is the nasopharynx of children. Carriage increases from birth and is maximal at pre-school age. Antimicrobial use in children is likely to have a significant influence on the susceptibility of pneumococci. Most studies looking for risk factors for resistance in pneumococci have identified antimicrobial use as a risk factor, especially the following aspects: ongoing, recent, repeated, frequent, and prophylactic antibiotic use. The effect of individual classes of antimicrobials has not been studied in detail but use of beta-lactam antibiotics and trimethoprim-sulpha has been associated with increased risk. Other risk factors are young age, nosocomial acquisition, prior hospitalization, and HIV infection. Day-care centers can facilitate the spread of resistant pneumococci and an Icelandic study showed that carriage of resistant pneumococci was associated with young age, domicile in an area with high antimicrobial consumption, recent antimicrobial use, frequent antimicrobial use, and use of trimethoprim-sulpha. The rapid increase of penicillin-resistant pneumococci in Iceland was met with propaganda against overuse of antimicrobials, which lead to reduction of antimicrobial use and subsequently a reduced incidence of penicillin-resistant pneumococci. This reduction may be related to reduced antimicrobial use. Reducing antimicrobial use should be considered important for programs aimed at reducing antimicrobial resistance.

Rate of carriage, serotype distribution and penicillin resistance of Streptococcus pneumoniae in healthy children

This study was aimed to define the carriage rates for Streptococcus pneumoniae in a given population in Ankara and also to determine the serotypes and penicillin resistance of these strains. Oropharyngeal swabs were taken from a total of 661 children aged between 0-11 years and living in a province of Ankara between January 1995-January 1997. Serotyping was performed by detection of the Quellung reaction. The isolates were screened for penicillin susceptibility by the agar dilution method according to the guidelines of NCCLS. The total rate of pneumococcal carriage in the study population was 23.90% and the isolation rate was found to be statistically associated with age, being higher in small children. Among the 158 S. pneumoniae isolates, the most prevalent serotypes (in order of frequency) were 6, 19, 9, 23, 3 and 14. Penicillin susceptibility was examined in 120 of the isolates. 55 of them (45.83%) were susceptible, 53 (44.17%) were intermediately and 12 (10.0%) were highly resistant to penicillin. Evaluation of the results showed that serotypes 6, 14 and 23 were those most often associated with penicillin resistance. The significant rate of isolation of penicillin-resistant pneumococci in healthy carriers points to the importance of active immunization in risk groups and also the importance of the rational use of antibiotics to limit the spread of resistant strains.

Carriage of penicillin-resistant pneumococci in Malawian children

In a prospective study of pneumococcal carriage in 200 Malawian children under 5 years of age, 47.5% were carriers. The carriage rate was highest in those aged 3-12 months and did not vary with family size, nor was it higher in those who had recently been admitted to hospital. Nasopharyngeal swabs were significantly more efficient than throat swabs in detecting carriers (p < 0.001) but nasopharyngeal swabs alone would have missed seven (8%) carriers. Pneumococcal isolates from 22% of carriers and from eight cases of meningitis and one of empyema showed intermediate resistance to penicillin (MIC 0.1-1.0 mg/l). All were sensitive to the 3rd-generation cephalosporin cefotaxime but one of the penicillin-resistant pneumococci and two of the clinical isolates had increased MICs of cefuroxime (0.5 mg/l).

Efficacies of cefotaxime and ceftriaxone in a mouse model of pneumonia induced by two penicillin- and cephalosporin-resistant strains of Streptococcus pneumoniae

We previously demonstrated the efficacy of ceftriaxone (CRO), at 50 mg/kg of body weight every 12 h, against a highly penicillin-resistant (MIC, 4 micrograms/ml) Streptococcus pneumoniae strain with low-level resistance to CRO (MIC, 0.5 microgram/ml) in a leukopenic-mouse pneumonia model (P. Moine, E. Vallée, E. Azoulay-Dupuis, P. Bourget, J.-P. Bédos, J. Bauchet, and J.-J. Pocidalo, Antimicrob. Agents Chemother. 38:1953-1958, 1994). In the present study, we assessed the activity of CRO versus those of cefotaxime (CTX) and amoxicillin (AMO) against two highly penicillin- and cephalosporin-resistant S. pneumoniae strains (P40422 and P40984) (MICs of 2 and 8 for penicillin, 2 and 4 for AMO, and 4 and 8 for CRO or CTX, respectively). Against both strains, a greater than an 80% cumulative survival rate was observed with CRO at a dose of 100 or 200 mg/kg every 12 h (dose/MIC ratio, 25). With CTX, a high dosage of 400 mg/kg (dose/MIC ratio, 100 or 50) administered every 8 h (TID) was needed to protect 66 and 75% of the animals, respectively, with no statistically significant differences versus CRO. Against the P40422 strain, CRO (100 mg/kg) produced the greatest bactericidal effect, from the 8th to the 24th hour after a single injection (1.8-log-unit reduction over 24 h), and the fastest bacterial pulmonary clearance during treatment; with CTX, only multiple injections at a high dosage, i.e., 400 mg/kg TID, demonstrated a significant bactericidal effect. AMO in a high dosage, 400 mg/kg (dose/MIC ratio, 200) TID, showed good activity only against the P40422 strain. Despite the identical MICs of CTX and CRO, the longer time (3.6 to 4.6 h) that serum CRO concentrations remained above the MICs for the pathogens at a dose of 100 mg/kg resulted in greater efficacy versus CTX against highly penicillin- and cephalosporin-resistant S. pneumoniae strains.

Relationship of MICs to efficacy of cefotaxime in treatment of Streptococcus pneumoniae infections

In June 1993, the National Committee for Clinical Laboratory Standards (NCCLS) recommended stringent new interpretive guidelines for antibiotics indicated for Streptococcus pneumoniae meningitis. To assess the predictive values of the recommended breakpoints, retrospective data were collected from patients who had S. pneumoniae infections and were treated with cefotaxime monotherapy. Susceptibilities based on the NCCLS interpretative categories were compared with clinical and bacteriologic outcomes. In 76 evaluable patients, the most common infections were bacteremia-septicemia (n = 49), meningitis (n = 37), and lower respiratory tract infection (n = 14). Under the NCCLS breakpoints proposed in 1993, 55 isolates would have been classed as susceptible to cefotaxime (MIC, < or = 0.25 microgram/ml), 18 would have been classed as intermediate (MIC, 0.5 to 1.0 microgram/ml), and 2 would have been classed as resistant (MIC, > or = 2 micrograms/ml). Of 75 cefotaxime-treated patients for whom cefotaxime MICs were recorded, 73 were clinically cured or improved (37 of 37 with meningitis and 36 of 38 with other infections). One case of bacteremia and one case of bone-and-joint infection were scored as therapeutic failures because initial monotherapy had to be modified because of an adverse drug reaction. Excluding these patients, there were 18 patients infected with S. pneumoniae that would have been classed as not fully susceptible (i.e., MICs > or = 0.5 microgram/ml); all of these patients were cured or improved. The results of this analysis demonstrate that successful treatment with cefotaxime did not correlate well with the guidelines for the susceptibility of pneumococcal isolates to either penicillin or cefotaxime established by the 1993 NCCLS breakpoint recommendations. Because of this study and other similar findings, the NCCLS adopted more clinically relevant guidelines in 1994.

An Outbreak of Penicillin-Resistant Streptococcus Pneumoniae Infections on an Internal Medicine Ward

An outbreak of penicillin-resistant Streptococcus pneumoniae (PRSP) infections occurred in our hospital between January and May of 1993. Nine patients with infections/colonizations were located in 3 multiplebed rooms on an internal medicine ward. Two of the 9 patients developed pneumonia, 3 developed acute bronchitis, and 4 patients demonstrated colonization in the respiratory tract. Only 1 case of acute bronchitis was confirmed as a community-acquired infection, while the others were considered nosocomial infections, subsequently shown to be caused by at least 2 different bacterial strains. The cases of pneumonia were thought to be cross-infections transmitted by droplets. All patients with either pneumonia or bronchitis were cured by the administration of various antibiotics, including imipenem and ofloxacin. Of the 4 colonization cases, 3 patients were treated with antibiotics and the organisms successfully eradicated. Although all 5 patients with infections were cured, it is important to be attentive to the emergence of PRSP infections, as there are potential difficulties in the treatment of this organism.

Serotypes and resistance patterns of Streptococcus pneumoniae causing systemic disease in northern Norway

During the period 1985-1990, Streptococcus pneumoniae was isolated form 97 patients with systemic pneumococcal disease in Northern Norway. Systemic disease occurred most frequently in the age groups 0-4 years and > 60 years. An increasing incidence was observed, especially among children less than five years old. Serotypes covered by the 23-valent pneumococcal polysaccharide vaccine were found in 86 of 97 (88.7%) isolates. The vaccine did not cover 16.7% of the systemic isolates from children less than five years old. Reduced sensitivity to penicillin was found in one isolate (1.0%) which was resistant to ampicillin, doxycycline and chloramphenicol. The E-test and the Rosco agar diffusion test differed in sensitivity to penicillin, chloramphenicol, ciprofloxacin and erythromycin. Three serotype 12F strains showed unusual cross-resistance to chloramphenicol and erythromycin.

Streptococcus pneumoniae resistant to penicillin: incidence and potential therapeutic options

Streptococcus pneumoniae was recovered from 12 (50%) samples of middle ear fluid of 24 consecutive patients with AOME and in mixed culture of middle ear pathogens from one (4%) additional specimen. Two (15.3%) isolates had intermediate resistance to penicillin (minimal inhibitory concentration (MIC) 0.125 and 1.0 micrograms/mL). The antimicrobial susceptibility to various antimicrobials of 30 S pneumoniae strains recovered from patients seen in the last 12 months was also determined. One of the patients with AOME developed bacteremia that resolved uneventfully, whereas the other developed meningitis. MIC90 was determined from penicillin (2 micrograms/mL), erythromycin (> 32 micrograms/mL), cefaclor (32 micrograms/mL), loracarbef (> or = 64 micrograms/mL), cefixime (16 micrograms/mL), ceftibuten (> 64 micrograms/mL), chloramphenicol (16 micrograms/mL), cefpodoxime (4 micrograms/mL), ciprofloxacin (2 micrograms/mL), cephalexin (> or = micrograms/mL), augmentin (2 micrograms/mL), cefprozil (8 micrograms/mL), clindamycin (64 micrograms/mL), TMP-SXT (> 64 micrograms/mL), clarithromycin (32 micrograms/mL), rifampin (0.06 micrograms/mL), cefuroxime (2 micrograms/mL), cefotaxime (0.25 micrograms/mL), vancomycin (0.25 micrograms/mL), and imipenem (0.5 micrograms/mL). Cefprozil, vancomycin, and rifampin inhibited all strains, whereas cefpodoxime, cefuroxime, clindamycin, and clarithromycin exhibited very good activity.

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

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

Penicillin resistance among Streptococcus pneumoniae in Europe

Penicillin resistance in Streptococcus pneumoniae, which has been occasionally described in European isolates since the early 1970s, presently constitutes a general problem, although its rate may vary largely between countries and areas. Spain and Hungary show the highest rates of resistance and were probably the starting point for further dissemination to adjacent and distant countries. In Europe, resistant strains belong predominantly to serotypes 6, 9, 14, 19, and 23, and are isolated more frequently from pediatric than from adult patients, and from respiratory and CSF samples rather than blood. Although penicillin resistance in pneumococci is usually a well-recognized problem, some difficulties, mainly related to methodologic aspects of in vitro susceptibility testing, still subsist for its proper surveillance, but may be overcome through the adoption of adequate diagnostic protocols and tools.

Distribution of serotypes and antimicrobial resistance of Streptococcus pneumoniae strains isolated in Brazil from 1988 to 1992

Forty-two serotypes were identified among 288 Streptococcus pneumoniae strains isolated from patients living in Brazil. Serotyping was determined by the capsular typing test (Quellung reaction). Types 14 (10.4%), 6B (9.8%), 23F (8.0%), 5 (7.3%), 19F (6.9%), 6A (6.0%), and 1 and 4 (4.6%) were the most commonly identified strains. Two hundred twenty (76.4%) of the strains were of serotypes that are included in the 23-valent pneumococcal polysaccharide vaccine. If vaccine-related serotypes are also considered, the proportions of coverage in the vaccine are 82.3% (if type 6B alone is added) and 85.7% (if all the vaccine-related types are considered to be cross-protecting). Decreased susceptibility to penicillin, which was identified by using the 1-microgram oxacillin disk method as a screening test, was detected in 70 (26.7%) strains. The MICs of nine antimicrobial agents were determined by using the procedures recommended by the National Committee for Clinical Laboratory Standards. Seventy (35.9%) of the strains were resistant to tetracycline, 57 (29.2%) were resistant to sulfamethoxazole-trimethoprim, 3 (1.5%) were resistant to rifampin, 2 (0.80%) were resistant to penicillin, and 1 (0.5%) was resistant to chloramphenicol. The two penicillin-resistant strains were also resistant to or had decreased susceptibilities to cephalosporins. Forty-seven (17.9%) of the strains were intermediately resistant to penicillin, 17 (8.7%) were intermediately resistant to tetracycline, 13 (6.7%) were intermediately resistant to chloramphenicol, 12 (6.1%) were intermediately resistant to erythromycin, and 6 (3.1%) were intermediately resistant to rifampin.

Meningitis due to penicillin resistant Streptococcus pneumoniae occurring in a patient on long term ampicillin prophylaxis

A patient with persistent dural fistula, CSF rhinorrhoea and a history of recurrent bacterial meningitis developed meningitis with a penicillin-resistant strain of Streptococcus pneumoniae while on prophylactic ampicillin. The microbiological aspects of management are discussed.

Capsular types and susceptibility to penicillin of pneumococci isolated from cerebrospinal fluid or blood in Denmark, 1983-1988

By means of the capsular reaction test, we typed 2,294 pneumococcal strains isolated from blood or cerebrospinal fluid (CSF) in Denmark during 1983-88.91% of the strains belonged to types included in the 23-valent vaccine. Among 254 pneumococcal isolates from blood and CSF from Danish children, types 6A + 6B, 18C, 14, 7F, 1 and 19F, in that order of frequency, were the most common ones, accounting for 68%. Among 2,031 pneumococcal strains from adults, the most common isolates were types 1, 3, 14, 7F, 4, and 6A + 6B, accounting for 50% of all pneumococcal strains isolated from patients with invasive disease. Penicillin-resistant invasive strains of Streptococcus pneumoniae are rare in Denmark (< 1%).

Audit of the use of erythromycin in the treatment of community-acquired lower respiratory infections

The British Thoracic Society (BTS) guidelines for the treatment of community-acquired pneumonia recommend initial therapy with a betalactam antibiotic, with the addition of erythromycin if there are features of an atypical pneumonia. To see if these guidelines were being followed, a prospective study was undertaken of all adult patients admitted to hospital over a 3-month period who were given erythromycin for a community-acquired lower respiratory tract infection. Erythromycin was given to 62 patients who could be fully assessed. Continued prescription of erythromycin was justified in 10 (16%)--two patients with penicillin allergy, two with M. catarrhalis infection and one patient with legionnaires disease. Five patients had infections severe enough on admission to warrant combined therapy in line with the BTS recommendations. Five patients had erythromycin stopped on day 2. Erythromycin was prescribed on admission and continued unnecessarily in 47/62 patients, showing that the BTS recommendations are not being followed correctly.