Penicillin-resistant Isolates Research Articles

In-vitro activity of sanfetrinem against isolates of Streptococcus pneumoniae and Staphylococcus aureus

The activity of sanfetrinem (previously GV104326), was assessed against 168 isolates of Streptococcus pneumoniae and 90 isolates of Staphylococcus aureus. These isolates included a range of serotypes or phage types, and varied in their susceptibility to other antibiotics. Sanfetrinem exhibited good anti-pneumococcal activity, with MIC90s of < or = 0.007 mg/L and 0.5 mg/L for penicillin-susceptible and penicillin-resistant isolates, respectively. Sanfetrinem was also active against methicillin-susceptible staphylococci (MIC90 = 0.06 mg/L). However, the MICs of sanfetrinem for isolates with methicillin MICs of 8-16 mg/L and > or = 32 mg/L were 0.25-1 mg/L and 8->32 mg/L, respectively.

The impact of HIV on Streptococcus pneumoniae bacteraemia in a South African population

To determine the impact of HIV infection on Streptococcus pneumoniae bacteraemia in adults and children by analysing the prevalence and clinical features of such diseases and determining the prevalent serotypes/serogroups and susceptibility patterns of isolates. Patients were identified prospectively from January to October 1996. Chris Hani Baragwanath Hospital, Soweto, a tertiary referral hospital treating adults and children, in an urban district near Johannesburg, South Africa. All patients with S. pneumoniae isolated from blood culture by the Microbiology Department, Chris Hani Baragwanath Hospital were studied. Clinical and microbiological features were recorded. A total of 178 patients with S. pneumoniae were investigated as part of the study; 49 were aged < 13 years. HIV seroinfection was present in 25 (51%) children and 58 (45%) adults. The incidence of S. pneumoniae bacteraemia was 36.9-fold increased in HIV-seropositive children and 8.2-fold increased in HIV-seropositive adults compared with HIV-seronegative individuals. Both adult and paediatric HIV-seropositive patients with S. pneumoniae bacteraemia were significantly younger than HIV-seronegative patients. Pneumonia was a significantly more common presentation in HIV-seropositive children, otherwise the spectrum of disease and outcome were similar in HIV-seronegative and positive groups. Serotype 1 S. pneumoniae isolates were significantly less common in HIV-infected individuals (both adults and children). Resistance to penicillin was increased in S. pneumoniae isolates from HIV-infected patients (significant in adults). Patients with penicillin-resistant isolates did not have a poorer outcome. The potential coverage of serotypes/serogroups included in the proposed nine-valent conjugate pneumococcal vaccine was 88% in HIV-seronegative children and 83% in HIV-seropositive children. The potential coverage of the currently available 23-valent pneumococcal vaccine for adults was 98.2 and 100)% for HIV-infected and HIV-uninfected adults, respectively. The burden of bacteraemia due to S. pneumoniae in HIV-seropositive individuals admitted to our hospital is considerable. Differences in the S. pneumoniae serotypes/serogroups in HIV-infected patients have been demonstrated with resultant differences in antibiotic susceptibility patterns. Excellent potential for vaccine coverage was demonstrated for both HIV-seronegative and HIV-seropositive individuals. Further studies are necessary to test the clinical efficacy of pneumococcal vaccination of HIV-seropositive adults and children as a potential preventative measure against this prevalent disease.

CHANGING PATTERNS OF ETIOLOGY AND RESISTANCE IN COMMUNITY-ACQUIRED RESPIRATORY TRACT INFECTIONS

Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis cause up to 80% of community-acquired bacterial respiratory tract infections. An tibiotic resistance to these pathogens is a global problem. The prevalence of penicillin-resistant S. pneumoniae is as high as 50%. Most penicillin-resistant isolates are also resistant to unrelated antibiotics that are commonly used as alternatives to penicillin. The prevalence of ampicillin-resistant H. influenzae is as high as 35% of isolates, and resistance to other antibiotics can also be high. Nearly all isolates of M. catarrhalis are ampicillin-resistant, but resistance to other antibiotics is rare. Antibiotic resistance could be limited by rational antibiotic use. Ongoing surveillance of re sistance patterns is essential.

Molecular epidemiology of penicillin-resistant Streptococcus pneumoniae isolated in central Taiwan

Previous studies have suggested that penicillin-resistant pneumococcal isolates (especially those with MIC >1 μg/mL) usually are clonally related. To test this hypothesis, the molecular epidemiology of 29 clinical isolates of penicillin-resistant pneumococci (of which 83% were also resistant to either cefotaxime or ceftriaxone) collected in central Taiwan was investigated by pulsed field gel electrophoresis. Twenty-seven distinct patterns were identified. Our results indicate that an increase in penicillin-resistant S. pneumoniae between April 1993 and June 1994 in central Taiwan is not due to the clonal dissemination of a limited number of epidemic strains.

Antimicrobial susceptibility of viridans group streptococci in Taiwan with an emphasis on the high rates of resistance to penicillin and macrolides in Streptococcus oralis.

The in-vitro susceptibilities of 13 antimicrobial agents were determined for 207 isolates of viridans group streptococci recovered from patients with significant infections in Taiwan during 1995 and 1997. Variable degrees of susceptibility existed among nine species. High-level penicillin resistance (MIC > or = 4.0 mg/L) was found most frequently in Streptococcus oralis (35%), followed by Streptococcus mitis (20%) and Streptococcus salivarius (8%). However, S. salivarius showed the lowest rate of susceptibility to penicillin (50%). Macrolide resistance also occurred most frequently in S. oralis isolates (55%) but in none of Streptococcus mutans. Penicillin and macrolides tended to be less active against isolates recovered from non-invasive sites than against those isolated from invasive sites. Imipenem was the most active beta-lactam against penicillin-resistant isolates. Ofloxacin, vancomycin and teicoplanin showed good in-vitro activity against all isolates, with MIC90s of 2, 1 and 0.25 mg/L, respectively. None of these isolates displayed high-level resistance to gentamicin and most isolates were susceptible to chloramphenicol. These results indicate the species-related variability of susceptibility, especially to penicillin, macrolides and tetracycline. In addition to S. mitis, S. oralis also displayed high rates of resistance to penicillin and macrolides. The difference in susceptibilities between species of viridans streptococci indicates the importance of accurate identification and the need for continuing surveillance of antimicrobial resistance.

Alterations in PBP 1A essential-for high-level penicillin resistance in Streptococcus pneumoniae.

High-level penicillin resistance in pneumococci is due to alterations in penicillin-binding proteins (PBPs) 2X, 2B, and 1A. We have sequenced the penicillin-binding domain of PBP 1A from penicillin-resistant South African pneumococcal isolates and have identified amino acid substitutions which are common to all the resistant isolates analyzed. Site-directed mutagenesis was then used to determine whether particular amino acid substitutions at specific positions in PBP 1A mediate penicillin resistance. PCR was used to isolate PBP 2X, 2B, and 1A genes from clinical isolate 8303 (penicillin MIC, 4 micrograms/ml). These wild-type PBP genes were cloned into pGEM-3Zf and were used as the transforming DNA. Susceptible strain R6 (MIC, 0.015 microgram/ml) was first transformed with PBP 2X and 2B DNA, resulting in PBP 2X/2B-R6 transformants for which MICs were 0.25 microgram/ml. When further transformed with PBP 1A DNA, 2X/2B/1A-R6 transformants for which MICs were 1.5 micrograms/ml were obtained. Site-directed mutagenesis of the PBP 1A gene from isolate 8303 was then used to reverse particular amino acid substitutions, followed by transformation of PBP 2X/2B-R6 transformants with the mutagenized PBP 1A DNA. For PBP 2X/2B/1A-R6 transformants, the introduction of the reversal of Thr-371 by Ser or Ala in PBP 1A decreased the MIC from 1.5 to 0.5 micrograms/ml, whereas the reversal of four consecutive amino acid substitutions (Thr-574 by Asn, Ser-575 by Thr, Gln-576 by Gly, and Phe-577 by Tyr) decreased the MIC from 1.5 to 0.375 micrograms/ml. These data reveal that amino acid residue 371 and residues 574 to 577 of PBP 1A are important positions in PBP 1A with respect to the interaction with penicillin and the development of resistance.

Application of molecular typing to the epidemiology of Streptococcus pneumoniae.

The spread of antibiotic resistance and the development of new vaccines have focused attention on the epidemiology of Streptococcus pneumoniae over recent years. While serotyping and the determination of antibiotic...

Emergence of penicillin-resistant Streptococcus pneumoniae ocular infections.

Approximately 15-20% of Streptococcus pneumoniae clinical isolates in the United States are not susceptible to penicillin. Isolates with a minimum inhibitory concentration (MIC) of 0.12-1.0 mg/ml are intermediately resistant, and those with an MIC > 2.0 microg/ml are classified as having high-level penicillin resistance. We determined the proportion of penicillin-resistant S. pneumoniae recovered from ocular and periocular infections from 1976 through 1995, compared these cases with penicillin-susceptible controls, and evaluated the susceptibility of penicillin-resistant isolates to selected cephalosporins and fluoroquinolones. MICs for cephalothin, ceftazidime, ciprofloxacin, and ofloxacin were determined for available isolates by the E test. We performed a case-comparison study to evaluate differences between patients with penicillin-susceptible and -nonsusceptible ocular pneumococcal infections. Of 173 ocular isolates of S. pneumoniae isolated in the 20-year period, 12 (7%) were not susceptible to penicillin, including eight (5%) intermediate isolates and four (2%) highly resistant isolates. Penicillin-intermediate and -resistant pneumococci were recovered at a rate of none of 46 isolates from 1976 through 1980, one (4%) of 25 from 1981 through 1985, one (2%) of 51 from 1986 through 1990, and 10 (20%) of 51 from 1991 through 1995 (p < 0.0004). We found no significant differences in presenting characteristics between patients with ocular infections due to penicillin-susceptible pneumococci and those caused by nonsusceptible strains. All retested isolates with intermediate susceptibility to penicillin had a cephalothin MIC < or = 1.5 microg/ml, and all retested isolates with high-level penicillin resistance had a cephalothin MIC > or = 4 microg/ml. The ceftazidime MIC for all penicillin-resistant isolates was > or = 24 microg/ml. All penicillin-nonsusceptible isolates had MICs < or = 1.5 microg/ml for ciprofloxacin and < or = 3 microg/ml for ofloxacin. Penicillin resistance has recently emerged among ocular S. pneumoniae. Cephalothin, ciprofloxacin, and ofloxacin have good activity against some ocular isolates with intermediate penicillin susceptibility, although another agent such as vancomycin may be needed for pneumococci with high-level penicillin-resistance.

Rapid detection of penicillin-resistant Streptococcus pneumoniae in cerebrospinal fluid by a seminested-PCR strategy.

A seminested-PCR assay, based on the amplification of the pneumococcal penicillin-binding protein 2B gene (pbp2B), was developed for the detection of penicillin-resistant and -susceptible pneumococci in cerebrospinal fluid (CSF) specimens. Species-specific primers (P5 and P6) which amplified a 682-bp conserved region of the transpeptidase-encoding region of the pbp2B gene were used. Four "resistance" primers were designed to bind to altered areas of the pbp2B gene identified in penicillin-resistant South African wild-type strains. Together with the downstream primer P6, the upstream resistance primers amplified fragments which were used to detect the presence of penicillin resistance. This system identified all 35 of the S. pneumoniae isolates evaluated, including strains of 11 different serotypes and a range of penicillin-resistant and -susceptible strains. The specificity of the assay was demonstrated by its inability to amplify DNA from other bacterial species which commonly cause meningitis. It was possible to detect pneumococcal DNA from culture-negative CSF inoculated with 2.5 pg of purified DNA or 18 CFU. Analysis of 285 CSF specimens showed that PCR detected the pneumococcus in 18 samples positive by culture, including the identification of four penicillin-resistant isolates. The positive predictive value and the negative predictive value of the assay were each 100%.

Predominance of the multiresistant 23F international clone of Streptococcus pneumoniae among isolates from Mexico.

During a surveillance study to determine the relative prevalence of capsular types of Streptococcus pneumoniae and antimicrobial susceptibility of invasive isolates in children <5 years old in Mexico City, 220 isolates were collected. The serotype 23F was the most common found, followed by types 6A + B, 14, 19F, and 19A. Diminished susceptibility to penicillin was detected in 106 isolates (48.2%), and high penicillin resistance was found in 49 strains (22.2%), 31 belonging to type 23F. Resistance was also observed to erythromycin (13.1%), to chloramphenicol (43.1%), and to cefotaxime (10.9%). No strains were resistant to ofloxacin or vancomycin. Forty-four of the highly penicillin resistant isolates (penicillin MIC > or =2.0 microg/ml) were examined with molecular fingerprinting techniques; 29 (65.9%) of these isolates (all except two strains) were serotype 23F and shared subtype variants of PFGE type A characteristic of the internationally spread Spanish/USA clone of S. pneumoniae. These strains were also resistant to trimethoprim/sulfametoxasole (TMP/SMX), chloramphenicol, and tetracycline, and most of them were susceptible to erythromycin. Another 6 of the highly penicillin-resistant strains (serogroups 9 and 14) showed PFGE fingerprints and antimicrobial susceptibility pattern characteristic of a second internationally spread clone (French/Spanish clone) and carried resistance to penicillin and TMP/SMX. The rest of the 9 penicillin-resistant isolates were represented by 7 distinct additional PFGE types. The findings suggest that almost 80% of all highly penicillin resistant strains may have been "imported" into Mexico.

Antimicrobial susceptibility profiles of oropharyngeal viridans group streptococci isolates from cystic fibrosis and non-cystic fibrosis patients.

The antimicrobial susceptibility profile of 77 oropharyngeal viridans streptococci isolates from 34 cystic fibrosis (CF) patients and 58 isolates from 43 healthy non-CF patients were studied by the E-test and the standard disk diffusion methods. Overall penicillin and cefotaxime resistances (intermediate plus resistant isolates) were significantly higher (p < 0.05) among CF isolates (72.7% and 45.5%, respectively) than among non-CF isolates (51.7% and 15.5%, respectively). No significant difference was observed in overall (intermediate plus resistant) erythromycin resistance rates, although high-level erythromycin resistance (> or =32 microg/mL) was more frequently found in CF isolates (24.6%) than in non-CF isolates (12.1%). An unexpected high percentage of isolates showed low level erythromycin resistance (MIC range, 0.5-15 microg/mL): 41.5% in cystic fibrosis and 46.5% in non-CF isolates. No significant differences were observed regarding the percentage of colonized patients with at least one penicillin-resistant isolate. On the contrary, colonization with cefotaxime (p < 0.001) or erythromycin (p = 0.014) resistant isolates were significantly more prevalent in CF patients. Similar tetracycline and chloramphenicol resistance rates were observed for both groups. Viridans isolates resistant to a single antibiotic were more prevalent among non-CF patients and multiple resistance was higher among CF patients. Prior antibiotic exposure could result in differences in beta-lactam resistance and colonization rates with resistant isolates between both groups. None of the non-CF patients was previously treated with antimicrobials for a period of three months before sampling. In contrast, 94.1% of CF patients were treated with antimicrobials within the same period; 65.6% with beta-lactam antibiotics. Patients with CF disease, frequently exposed to antimicrobials, may be a reservoir of viridans streptococci isolates with resistance determinants, particularly to beta-lactam antibiotics.

Epidemiological study on penicillin-resistant Streptococcus pneumoniae

We studied the differences among clinical isolates of Penicillin-resistant Streptococcus pneumoniae by polymerase chain reaction (PCR) of pbp2b gene, followed by serotyping and pulsed field gel electrophoresis (PFGE) analysis. Clinical isolates were recovered from sputum samples from patients with respiratory infection in Tottori University Hospital between June 1986 and May 1996. By PCR, altered pbp2b genes of the resistant isolates were detected in 76.5%. The percentages of the isolates that had altered pbp2b genes increased concomitantly with the minimum inhibitory concentration (MIC). By serotyping the percentage of 19F, 23F, 6B and 14 was 54.5%, 18.2%, 9.1% and 9.1% respectively. The frequency of isolates resistant to penicillin increased rapidly from 1991 in this hospital and most isolates belonged to serotype 19F. The resistant isolates in this hospital and 4 clinical resistant isolates of S. pneumoniae 19F in a second hospital were studied by PFGE. 14 of 18 resistant 19F isolates in this hospital and all 19F isolates from the second hospital presented an identical pattern. The remaining 4 samples were similar though not completely identical. These results indicate that the penicillin resistant 19F isolates have a common clonal origin and have spread rapidly from 1991 in this hospital.

Susceptibility to New β-Lactams of Enterobacterial Extended-Spectrum β-Lactamase (ESBL) Producers and Penicillin-Resistant Streptococcus pneumoniae in Mexico

The activities of several β-lactam antimicrobial agents, aminoglycosides and ciprofloxacin, were determined against 62 clinical isolates of enterobacteria resistant to oxyimino cephalosporins (extended-spectrum β-lactamase producers), collected during 1991 to 1993, and 16 penicillin-resistant invasive isolates of Streptococcus pneumoniae collected during 1994-1996. The numbers and percentages of susceptible enterobacterial strains to tested antibiotics were: imipenem 60 (97%), ciprofloxacin 57 (92%), cefepime 56 (90%), cefpirome 34 (55%), aztreonam 13 (21%), cefotaxime 7 (11%), ceftazidime 0 (0%), amikacin 11 (18%) and gentamicin 16 (26%). Despite the fact that these strains had never been exposed previously to cefepime or cefpirome, the susceptibility was 90% and 55%, respectively. No penicillin-resistant strains of S. pneumoniae were susceptible to cefotaxime, imipenem or cefepime. Only one strain was susceptible to ceftazidime and 4 (25%) were susceptible to cefpirome. Erythromycin showed the greatest activity with 12 (75%) susceptible strains.

Surveillance of Pneumococcal Resistance in Belgium During Winter 1996-1997

SummaryThis study tested 212 pneumococcal isolates from 9 institutions for their susceptibilities to penicillin, ampicillin, amoxycillin, amoxycillin/clavulanate, cefaclor, cefuroxime, cefotaxime, imipenem, tetracycline, erythromycin, and clarithromycin using NCCLS-standardized microdilution. Penicillin-insusceptibility was 12.3% [5.7% intermediate (0.12-1 μg/ml) and 6.6% high-level (≥ 2 μg/ml)], tetracycline-insusceptibility (≥4 μg/ml) 31.1%, and erythromycin-insusceptibility (≥0.5 μg/ml) 31.1 % as well. Erythromycin-insusceptible isolates showed cross-insusceptibility to clarithromycin. Penicillin-susceptible isolates were susceptible to all β-lactams. MICs of all β-lactams rose with those of penicillin for penicillin-insusceptible isolates. Ampicillin and penicillin were equally potent against penicillin-insusceptible isolates, imipenem, cefotaxime, and amoxycillin ± clavulanate were more potent (generally 5, 1, and 1 doubling dilution, respectively), and cefuroxime and cefaclor less potent (generally 1 and 6 doubling dilutions, respectively). Most penicillin-insusceptible isolates were high-level resistant to cefaclor (≥ 32 μg/ml). Although MICs of all β-lactams rose with those of penicillin, resistance to penicillin was not absolute in terms of cross-resistance. Most penicillin-intermediate and high-level penicillin-resistant isolates remained fully susceptible and intermediate, respectively, to amoxycillin ± clavulanate, cefotaxime, and imipenem, but not to cefuroxime. Penicillinin-susceptible isolates were 76.9%, 42.3%, and 34.6% co-insusceptible to tetracycline, erythromycin, and tetracycline plus erythromycin, respectively. Most penicillin-, tetracycline-, and erythromycin-insusceptible isolates were of capsular types 23 ≫ 6 ≥ 19 ≥ 32, 19 ≥ 6 ≥ 28 ≥ 23, and 19 ≥ 6 ≥ 14 ≥ 23, respectively. Compared to winter 1994-1995, insusceptibility to penicillin, tetracycline, and erythromycin rose by some 4%, 4%, and 13%, respectively.

Streptococcus pneumoniae blood culture isolates from patients with and without human immunodeficiency virus infection: alterations in penicillin susceptibilities and in serogroups or serotypes.

We performed a 3-year retrospective study of Streptococcus pneumoniae blood culture isolates recovered at Baragwanath Hospital, Soweto, South Africa, from 1993 to 1995. The study group comprised 457 patients, including 98 children, of known human immunodeficiency virus (HIV) serostatus. Of these patients, 70 (30 [8.4%] of 359 adults and 40 [40.8%] of the 98 children) were infected with penicillin-resistant S. pneumoniae strains (minimal inhibitory concentration, > or = 0.12 microg/mL); 56 of these strains were intermediately resistant to penicillin. HIV-positive patients had significantly more penicillin-resistant isolates than did HIV-negative patients (43 [29.7%] of 145 HIV-positive patients vs. 27 [8.6%] of 312 HIV-negative patients; P < .001); this difference was found for both adults (19% vs. 4.3%; P < .001) and children (53.3% vs. 30.2%; P < .0343). Multiple resistance occurred more frequently in HIV-positive children (P = .02). HIV-positive adults had a statistically significant increase in the percentage of serogroups and serotype usually found in children and commonly associated with antimicrobial resistance, i.e., serotype 14 and serogroups 6, 19, and 23 (48% vs. 28.6%; P < .001). The increased prevalence of serogroups or serotypes usually found in children was also found among penicillin-susceptible strains. These data suggest that HIV-infected adults may again become susceptible to the serogroups or serotypes found in children.

Middle ear fluid concentrations of amoxicillin after large dosages in children with acute otitis media.

Middle ear fluid concentrations of amoxicillin after large dosages in children with acute otitis media.

Penicillin-resistant Streptococcus pneumoniae in the Netherlands: results of a 1-year molecular epidemiologic survey.

The molecular epidemiologic characteristics of penicillin-resistant pneumococci in the Netherlands were investigated in 1995. Dutch electronic surveillance data showed that 0.7% of all pneumococci were intermediately resistant and 0.4% were highly resistant to penicillin. From March 1995 to March 1996, 89 penicillin-resistant isolates were collected by 39 medical microbiology laboratories. Thirty different genotypes were observed by restriction fragment end labeling. Twenty-one DNA types were unique, whereas 9 distinct genotypes were shared by > or = 2 isolates. Different serogroups were found within 6 of the 9 genetically identical clusters of penicillin-resistant isolates, suggesting that horizontal transfer of capsular genes is common. Finally, nosocomial transmission of penicillin-resistant pneumococci was observed among 21 elderly adults with chronic obstructive pulmonary disease. This study demonstrates that multiple clones of penicillin-resistant pneumococci have been introduced in the Netherlands, a country with a low prevalence of pneumococcal infection. Some clones spread among the population in and outside hospitals.

In vitro activities of oral antimicrobial agents against penicillin-resistant Streptococcus pneumoniae: implications for outpatient treatment.

We tested 83 penicillin-intermediate (Peni) and 50 penicillin-resistant (Penr) isolates of Streptococcus pneumoniae against eight oral antimicrobials. Clarithromycin's MICs (minimal inhibitory concentration) were generally the same or one to two dilutions less than those of azithromycin. Seventy-two percent of Peni isolates were susceptible to clarithromycin and azithromycin, in contrast to 42% and 40%, respectively, of Penr isolates. Cefuroxime activity exceeded that of cefprozil, which exceeded that of cefaclor, in Peni isolates. For all three cephalosporins, MICs of 90% of isolates tested were > or = 3 dilutions higher for Penr isolates than for Peni isolates. Percentages of Peni isolates susceptible to clindamycin and tetracycline were 92% and 83%, respectively, and 78% and 82% for Penr. Only 49% of Peni isolates and 4% of Penr isolates were susceptible to trimethoprim-sulfamethoxazole. Azithromycin, clarithromycin, cefuroxime, cefprozil, clindamycin, and tetracycline may be useful in treating infections caused by Peni S pneumoniae, but Penr isolates are frequently resistant to both old and newer agents.

Risk factors for penicillin-resistant systemic pneumococcal infections in children.

The purpose of this study was to identify risk factors that may differentiate children who develop systemic infections with resistant strains of Streptococcus pneumoniae from those who develop penicillin-susceptible pneumococcal infections. A retrospective case-controlled study was performed of all patients with positive blood and/or cerebrospinal fluid isolates for S. pneumoniae over a 13 1/2-month period. Patients with penicillin-susceptible strains of S. pneumoniae were compared with those with penicillin-resistant infections in terms of age, race, gender, diagnosis, underlying conditions, antibiotic therapy within 1 month prior to systemic infection, treatment, and outcome. Sixty-nine patients with systemic pneumococcal infections were identified over the study period. Nine (13%) of these patients had infection with a penicillin-resistant isolate. Six of these patients were infected with a relatively resistant strain (MIC 0.1-1.0 microgram/mL) while three were infected with a fully resistant strain (MIC > or = 2.0 micrograms/mL). There was no difference between the two groups in terms of age, race, gender, underlying diagnosis, treatment, or outcome. Sixty-seven percent of the patients who developed a penicillin-resistant pneumococcal infection had received antibiotics in the month prior to systemic illness versus 4% of those infected with a penicillin-susceptible strain (P < 0.0000097). In conclusion, when compared with children who develop systemic infection with a penicillin-susceptible strain of S. pneumoniae, children who develop infection with a penicillin-resistant strain are significantly more likely to have received antibiotics within 1 month prior to their illness.

Antimicrobial resistance of invasive Streptococcus pneumoniae in Slovenia, 1993-1995. The Slovenian Meningitis Study Group.

The susceptibility of 108 Streptococcus pneumoniae strains isolated from normally sterile body sites during 1993-1995 in Slovenia has been studied. Overall resistance to penicillin, erythromycin, trimethoprim-sulfamethoxazole, cefuroxime, cefaclor and chloramphenicol was 16.6, 0.9, 26.8, 0, 4.5 and 4.6%, respectively. All penicillin-resistant isolates (intermediate resistance) were susceptible to cefotaxime, ceftriaxone and vancomycin. Isolates less susceptible to penicillin were also significantly less sensitive to chloramphenicol, cefaclor and trimethoprim-sulfamethoxazole than penicillin-sensitive strains. Pneumococci isolated in children were significantly (p < 0.05) more resistant to trimethoprim-sulfamethoxazole than those isolated in adults. The study demonstrated moderate resistance rate of S. pneumoniae to penicillin and trimethoprim-sulfamethoxazole and a low-level resistance rate to erythromycin, cefaclor and chloramphenicol. No straightforward correlation between overall consumption of antibiotics and antimicrobial resistance was found.