Penicillin-resistant Streptococcus pneumoniae in Colombia: presence of international epidemic clones. Colombian pneumococcal study group

Evolution of Penicillin Non-susceptibility Among Streptococcus pneumoniae Isolates Recovered From Asymptomatic Carriage and Invasive Disease Over 25 years in Brazil, 1990-2014

Streptococcus pneumoniae is a major cause of community-acquired pneumonia and meningitis, and it is also found as a commensal, colonizing the human upper respiratory tract of a portion of the human population. Its polysaccharide capsule allows the recognition of more than 90 capsular types and represents the target of the currently available pneumococcal conjugate vaccines (PCVs), such as the 10-valent (PCV10) and the 13-valent (PCV13). Penicillin non-susceptible pneumococci (PNSP) have been listed as one of the current major antimicrobial-resistant pathogen threats. In Brazil, the emergence of PNSP was initially detected in the mid 1990s and PCV10 has been part of the National Immunization Program since 2010. Here, we investigated the distribution of capsular types and penicillin susceptibility profiles of 783 pneumococcal strains isolated in Brazil between 1990 and 2014 to assess the evolution of penicillin non-susceptibility among pneumococci associated with asymptomatic carriage and invasive pneumococcal disease (IPD). The most common serotypes among carriage isolates were 19F, 6B, 6C, 23F, and 14. Among IPD isolates, the most frequent types were 14, 3, 6B, 5, 19F, and 4. We detected 21 types exclusively associated with IPD isolates, whereas non-typeable (NT) isolates were only detected in carriage. Nearly half of the isolates belonged to PCV10 serotypes, which remarkably decreased in occurrence (by nearly 50%) after PCV10 introduction (2011–2014), while non-PCV10 serotypes increased. PNSP frequency and levels were much higher among carriage isolates, but PNSP belonging to PCV10 serotypes were more common in IPD. While the occurrence of PNSP has decreased significantly among IPD isolates since 2011, it kept increasing among carriage strains. Such a difference can be attributed to the serotypes that emerged in each clinical source after PCV10 usage. PNSP with multidrug resistance profiles that emerged within carriage isolates comprised mostly serotypes 6C and 35B, as well as NT isolates. In turn, penicillin-susceptible capsular types 3, 20, and 8 have risen among IPD. Overall, our results reinforce the relevance of PNSP surveillance over a long period of time to better understand the dynamics of antimicrobial resistance in response to PCV introduction and may also contribute to improve control measures toward drug-resistant pneumococci.

Otitis media today: a challenge for physicians and the community

Acute otitis media is one of the most common causes of medical consultation worldwide, and has a high economic impact. In this review, a clear definition between acute otitis media and otitis media with effusion is presented. The microbiology and characterization of the main bacterial isolates in acute otitis media and the susceptibility patterns are reviewed, and the latest concepts in antimicrobial treatment are discussed. The need for courses that improve the capability of primary care physicians to diagnose acute otitis media using pneumatic otoscopy, and for parental education is also discussed.

Molecular epidemiology of penicillin-susceptible non-beta-lactam-resistant Streptococcus pneumoniae isolates from Greek children

A total of 128 Streptococcus pneumoniae isolates that were susceptible to penicillin but resistant to non-beta-lactam agents were isolated from young carriers in Greece and analyzed by antibiotic susceptibility testing, serotyping, restriction fragment end labeling (RFEL), and antibiotic resistance genotyping. The serotypes 6A/B (49%), 14 (14%), 19A/F (11%), 11A (9%), 23A/F (4%), 15B/C (2%), and 21 (2%) were most prevalent in this collection. Of the isolates, 65% were erythromycin resistant, while the remaining isolates were tetracycline and/or trimethoprim-sulfamethoxazole resistant. Fifty-nine distinct RFEL types were identified. Twenty different RFEL clusters, harboring 2 to 19 strains each, accounted for 76% of all strains. Confirmatory multilocus sequence typing analysis of the genetic clusters showed the presence of three international clones (Tennessee(23F)-4, England(14)-9, and Greece(6B)-22) representing 30% of the isolates. The erm(B) gene was present in 70% of the erythromycin-resistant isolates, whereas 18 and 8% contained the mef(A) and mef(E) genes, respectively. The pneumococci representing erm(B), erm(A), and mef genes belonged to distinct genetic clusters. In total, 45% of all isolates were tetracycline resistant. Ninety-six percent of these isolates contained the tet(M) gene. In conclusion, penicillin-susceptible pneumococci resistant to non-beta-lactams are a genetically heterogeneous group displaying a variety of genotypes, resistance markers, and serotypes. This suggests that multiple genetic events lead to non-beta-lactam-resistant pneumococci in Greece. Importantly, most of these genotypes are capable of disseminating within the community.

Genetic relatedness of resistant and multiresistant Streptococcus pneumoniae strains, recovered in the Athens area, to international clones

The prevalence of resistance to antibiotics was examined among 318 Streptococcus pneumoniae strains isolated during 1998 and 1999 in a children's hospital in Athens. The rate of resistance to penicillin was 25.8% (intermediate 22%, resistant 3.8%); 42.5% of the strains were resistant to > or = 1 antibiotic and 20% were multidrug resistant. Resistance to penicillin was lowest in invasive strains (8.3%) and highest in ear isolates (31%). A review of the same microbiology laboratory's records revealed that there has been a gradual increase in penicillin resistance since 1988-1989, when it was 5%. Capsular types were determined for 77 strains resistant to > or = 1 antibiotic, and 69 (90%) of them belonged to the following five serotypes: 19F, 14, 9V, 23F, and 6B. Seventy-five strains were analyzed by pulsed-field gel electrophoresis (PFGE) and 59/75 (79%) shared five electrophoretic types. The largest cluster consisted of 19 serotype 19F strains, of which 18 were nonsusceptible to penicillin and most were multidrug resistant and shared a common and distinct electrophoretic pattern not resembling any known clone. A group of 17 strains that were nonsusceptible to penicillin belonged to serotypes 9V (10), 14 (6), and 19F (1) and shared a common PFGE type similar to the international clone Spain9V-3. Seven serotype 23F strains, of which five were multidrug resistant, belonged to the international clone Spain23F-1. Among the strains susceptible to penicillin but resistant to non-beta-lactam antibiotics, the largest cluster consisted of 13 isolates resistant to erythromycin that belonged to serotype 14 and shared an electrophoretic pattern characteristic of the clone England14-9. Finally, three serotype 6B strains were penicillin susceptible and multidrug resistant and had features similar to the Mediterranean 6B clone. The introduction and spread of several antibiotic-resistant international clones accounts at least in part for the increase in pneumococcal resistance observed in recent years in the Athens metropolitan area.

Dissemination of Streptococcus pneumoniae clone Colombia(5)-19 in Latin America

Streptococcus pneumoniae serotype 5 is the third most common capsular type causing invasive diseases in children younger than 5 years in Latin America. Preliminary data on Colombian serotype 5 isolates indicated a common clonal origin associated with resistance to tetracycline (TET) and chloramphenicol (CHL). We studied 172 S. pneumoniae serotype 5 invasive isolates from Argentina, Brazil, Colombia, Guatemala, Mexico, and Uruguay and confirmed the presence of the Colombia(5)-19 clone throughout Latin America. Fifteen subtypes of a pulsed-field gel electrophoresis pattern and 4 electrophoretic types (ET) were obtained. Most of the isolates from different geographical regions belonged to pattern A (34.3%), subtype A5 (41.9%), and ET1 (91.1%). The A pattern (n = 59) was resistant to TET and had variable resistance to CHL; it was present in Brazil (10.2%), Colombia (78%), Guatemala (8.5%), and Mexico (3.4%). Subtype A5 with variable susceptibility to TET and sensitive to CHL was found in Argentina (29.2%), Mexico (8.3%), and Uruguay (62.5%). Subtypes A1-A4, A7-A8, and A9-A11 (closely related to A) also shared ET1, while subtype A6 was assigned to ET1, ET2, and ET3. Eleven subtypes (n = 21) were found to be specific for one country each. In summary, the S. pneumoniae serotype 5 isolates from Latin American are genetically closely related but show different patterns of antibiotic resistance, probably as a result of horizontal transfer.

Antibiotic resistance in Streptococcus pneumoniae in six Latin American countries: 1993-1999 surveillance

The impact of invasive pneumococcal invasive disease is increased by the emergence of antibiotic resistance. We report regional and temporal variations in antibiotic resistance for 4,105 invasive Streptococcus pneumoniae isolates collected from Latin American children <5 years, between 1993 and 1999. Reduced susceptibility to penicillin was detected in 1,182 isolates (28.8%); 36% of these were resistant (> or = 2 microg/ml), including 12.6% with MIC > or = 4 microg/ml, occurring primarily in serotypes 14 and 23F. Reduced susceptibility to third-generation cephalosporins was detected in 12.1% of the collection. Mexico had the highest proportion of reduced susceptibility to penicillin (51.6%) and to third-generation cephalosporins (22%), whereas Brazil had the lowest at 20.9% and 0.7%, respectively. Isolates cultured from patients with pneumonia were more likely to have reduced susceptibility to third-generation cephalosporins than isolates from patients with meningitis (p < 0.0001). Susceptibility to trimethoprim-sulfamethoxazole, chloramphenicol, erythromycin, and vancomycin was tested by disk diffusion for 2.899 isolates. Reduced susceptibility was observed for 45.6%, 11.5%, 6.9%, and 0%, respectively. Thirty-one percent of the strains were resistant to > or = 2 drugs. High levels of antibiotic resistance in Latin America emphasize the need for the development of and adherence to rational antibiotic use guidelines. On-going surveillance will monitor the impact of these programs.

Presence of international multiresistant clones of Streptococcus pneumoniae in Colombia

In Colombia, penicillin resistance of Streptococcus pneumoniae invasive isolates recovered from children less than 5 years old has increased from 10% in 1994 to 49.4% in 1999, suggesting the circulation of international resistant clones in the country. A total of 167 S. pneumoniae invasive isolates with diminished susceptibility to penicillin (DSP) were studied. The techniques used were pulsed-field gel electrophoresis (PFGE) and restriction fragment length polymorphism (RFLP) of penicillin-binding proteins (PBPs) genes (2B, 2X, and 1A). Forty-nine serotype 23F isolates were grouped in two clusters: 15 (31%) multiresistant isolates showed PFGE pattern A and PBP I profile, thus making them indistinguishable from Spain23F-1 clone, and 34 (69%) with PFGE pattern C, PBP II profile, and intermediate level resistance (ILR) to penicillin and TMP-SMX, features unique to a Colombian clone. Fifty-five serotype 14 isolates were assigned to PFGE B pattern, PBP III profile, having high-level resistance to penicillin, and TMP-SMX, similar to the France9V variant 14. This same pattern was present in five capsular type 9V isolates. Four serotype 14 isolates were assigned to PFGE pattern F, and appeared to be similar to Slovakia(14)-10 PFGE pattern, although they had different PBP profiles. Nine capsular type 6B and one 6A isolates belonged to PFGE pattern M, similar to Spain6B-2, although they showed different PBP profiles. The remaining 44 isolates, corresponding to serotypes 14, 6B, 19F, and 34, showed variable PFGE and PBP patterns. These results show that as many as two international clones may be circulating in Colombia as well as a unique, widely distributed 23F clone with ILR to penicillin. Additionally, some Colombian isolates capsular type 14 and 6B might be related to Slovakia(14)-10 Spain6B-2 clones, respectively.

Evolution of Streptococcus pneumoniae serotypes and penicillin susceptibility in Latin America, Sireva-Vigía Group, 1993 to 1999. PAHO Sireva-Vigía Study Group. Pan American Health Organization

BACKGROUND

Since 1993 the Pan American Health Organization has coordinated a surveillance network with the National Reference Laboratories of Argentina, Brazil, Chile, Colombia, Mexico and Uruguay aimed at monitoring capsular types and antimicrobial susceptibility of Streptococcus pneumoniae causing invasive disease in children <6 years of age.

METHODS

The surveillance system included children 6 years of age and younger with invasive disease caused by S. pneumoniae. The identification, capsular typing and susceptibility to penicillin of the isolates were conducted using a common protocol, based on standard methodologies.

RESULTS

By June, 1999, 4,105 invasive pneumococcal isolates had been collected mainly from pneumonia (44.1%) and meningitis (41.1%) cases. Thirteen capsular types accounting for 86.1% of the isolates (14, 6A/6B, 5, 1, 23F, 19F, 18C, 19A, 9V, 7F, 3, 9N and 4) remained the most common types during the surveillance period. Diminished susceptibility to penicillin was detected in 28.6% of the isolates, 17.3% with intermediate and 11.3% with high level resistance. Resistance varied among countries and increased during this period in Argentina, Colombia and Uruguay. Serotypes 14 and 23F accounted for 66.6% of the resistance.

CONCLUSION

These surveillance data clearly demonstrate the potential impact of the introduction of a conjugate vaccine on pneumococcal disease and the need for more judicious use of antibiotics to slow or reverse the development of antimicrobial resistance.

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.

Pneumococcal surface protein A of invasive Streptococcus pneumoniae isolates from Colombian children

Pneumococcal surface protein A (PspA) elicits protection in mice against fatal bacteremia and sepsis caused by genetically diverse pneumococci and protects against carriage and lung infection. We determined the PspA families of invasive isolates of Streptococcus pneumoniae recovered from Colombian children <5 years of age. That 97.5% of Colombian isolates belong to PspA families 1 and 2 supports the hypothesis that a human PspA vaccine covering a few PspA families could be broadly effective.

Antibiotic resistance in Streptococcus pneumoniae

Resistance to penicillin and other antibiotics in Streptococcus pneumoniae has emerged in Australia and around the world in the past decade, and appears to be worsening (e.g., rates of penicillin resistance in Australia rose from 1% in 1989 to 25% in 1997). In Australia, the only oral antibiotic able to treat respiratory infections caused by some multiresistant strains is high-dose amoxycillin. If these strains increase in prevalence, then treatment failures for relatively minor infections (e.g., otitis media) are likely to become common, resulting in repeat antibiotic courses or hospitalisation for parenteral therapy. Therapy for meningitis caused by penicillin-sensitive pneumococcal strains remains high-dose benzylpenicillin, but empirical treatment while awaiting culture and sensitivity results is problematic; neither penicillin nor third-generation cephalosporins cover all strains. Therefore, many authorities recommend vancomycin, usually combined with a third-generation cephalosporin, for treating presumptive or proven pneumococcal meningitis pending penicillin-susceptibility results. As almost all readily available oral antibiotics in Australia select for resistant strains of pneumococci, multiresistant strains will increase in prevalence unless unnecessary antibiotic use and prescription volumes are reduced substantially in the next few years.

Molecular evolution in a multidrug-resistant lineage of Streptococcus pneumoniae: emergence of strains belonging to the serotype 6B Icelandic clone that lost antibiotic resistance traits

Since their first detection in 1988, penicillin-resistant Streptococcus pneumoniae isolates have rapidly spread in Iceland to account for close to 20% of all pneumococcal disease in that country by 1993. The major component (70%) of the resistant pneumococci identified from 1989 to 1992 was the progeny of a single multidrug-resistant clone (Icelandic clone) with a homogeneous chromosomal macrorestriction profile and identical multilocus enzyme type expressing serotype 6B and resistance to penicillin, tetracycline, chloramphenicol, erythromycin, and trimethoprim-sulfamethoxazole. The rest of the non-penicillin-susceptible isolates included bacteria with serotype 6A and serogroups 19 and 23. The unique geographic and epidemiological setting and the availability of a complete collection of all non-penicillin-susceptible isolates of S. pneumoniae in Iceland prompted us to carry out a molecular epidemiological study to monitor the fate of the Icelandic clone between 1989 and 1996; in addition, we wished to extend the characterization to representative groups of all non-penicillin-susceptible serotype 6B pneumococci which showed variations in antibiotype and which were recovered in Iceland between late 1989 and the end of 1996. Also included in the study were non-penicillin-susceptible isolates of serogroup 23. Pulsed-field gel electrophoresis of SmaI-restricted chromosomal DNA and Southern hybridization with the lytA DNA probe and probes specific for antibiotic resistance genes were used to characterize pneumococcal isolates. The results show that (i) the Icelandic clone remained the predominant type among penicillin-resistant S. pneumoniae through 1996; (ii) the emergence of variants of the Icelandic clone which had lost one or more of the antibiotic resistance phenotypes and/or resistant genes, singly or in combination, was documented during the surveillance period; and (iii) isolates belonging to the internationally spread multidrug-resistant serotype 23F clone were present in the Icelandic collection since late 1989 but did not increase in number during the subsequent years.

Prevalence and patterns of resistance of Streptococcus pneumoniae strains isolated from carriers attending day care centers in the area of Athens

The prevalence and patterns of Streptococcus pneumoniae resistance to antibiotics was examined in 146 nasopharyngeal carrier strains obtained during April and May, 1997, from 382 healthy children attending eight day care centers (DCCs) in the area of Athens. Reduced susceptibility to at least one antibiotic was found in 32.6% as follows: penicillin 11.4% (intermediate), cefotaxime 0.8% (intermediate), trimethoprim-sulfamethoxazole 22.7%, erythromycin 13.6%, tetracycline 11.4%, chloramphenicol 8.3%. Most of the nonsusceptible to penicillin isolates belonged to serogroups 23, 9, and 19. Multidrug resistance was detected in 11.4% of S. pneumoniae isolates including five penicillin nonsusceptible serogroup 23 strains. More than half of the multidrug resistant strains were susceptible to penicillin and belonged to serogroups 6 (4), 23 (1), 19 (1), and 1(1). Strains that belonged to the same serogroup/serotype and had identical resistance patterns appeared to cluster in some DCCs. Antibiotic use in the previous month was associated with reduced susceptibility to penicillin (p = 0.007) and multidrug resistance (p = 0.012). In conclusion, a moderate prevalence of reduced susceptibility to penicillin in pneumococcal carrier strains was found in our community. Multidrug resistance was common and was often associated with susceptibility to penicillin. Several distinct patterns of resistance were observed, suggesting the spread of resistant clones to our country.

Molecular characterization of penicillin-resistant Streptococcus pneumoniae isolates causing respiratory disease in the United States

Three hundred twenty-eight (328) penicillin-resistant Streptococcus pneumoniae isolates collected in 39 states of the United States between October, 1996, and March, 1997, from (mostly adult) patients with respiratory disease were characterized by microbiological, serological, and molecular fingerprinting techniques, including determination of chromosomal macrorestriction pattern with pulsed-field gel electrophoresis (PFGE) and hybridization with DNA probes specific for various antibiotic resistance genes. The overwhelming majority of the isolates were in five serogroups (23, 6, 19, 9, 14). All isolates had penicillin MIC values of at least 2 microg/ml, but the collection also included isolates with MIC values as high as 16 microg/ml. Virtually all isolates (96.6%) were resistant to trimethoprim/sulfamethoxazole (SXT) and many isolates were also resistant to chloramphenicol (43%), tetracycline (55%), and erythromycin (65%). Resistance to levofloxacin was extremely rare. The molecular fingerprinting methods showed that a surprisingly large proportion (167 out of 328, or 50.9%) of the isolates belonged to two international epidemic clones of S. pneumoniae: clone A (127, or 38.7%) with properties indistinguishable from that of the 23F multiresistant "Spanish/USA" clone widely spread in Europe, Asia, Latin America, and South Africa, and clone B (40, or 12.2%) belonging to the "French" serogroup 9/14 clone widely spread in Europe and South America. Virtually all members of clone A were also resistant to chloramphenicol (cat+), tetracycline (tetM+), and SXT, and about 75% were also resistant to erythromycin (mefE+ or ermB+). Close to 30% (39 out of 127) of the clone A isolates expressed anomalous serotypes (primarily serotypes 19 and 14, and nontypable) and most likely represented spontaneous capsular transformants. Most of the 40 isolates (35/40) belonging to clone B expressed serotype 9, with five of the isolates expressing serotypes 14 or 19, or were nontypable. All members of this clone were resistant to penicillin and SXT with only occasional isolates showing resistance to macrolides, tetracycline, and chloramphenicol. The combination of microbiological tests and DNA hybridizations also allowed the identification of unusual strains, for instance, isolates that reacted with the tetM or mefE DNA probes without showing phenotypic antibiotic resistance, an isolate showing phenotypic macrolide resistance without hybridizing with either the ermB or mefE DNA probes, or isolates that hybridized with both of these DNA probes. In addition to clones A and B, another large portion of the S. pneumoniae isolates (112 of 328, or 34.1%) was represented by eight clusters, each with a unique PFGE type. These clusters, together with the clone A and clone B isolates, made up 85% of all the penicillin-resistant isolates identified in this survey in the United States. Both international clones and the unique clusters showed wide geographic dispersal: Clone A was present in 30 of the 39 states and clone B in 18. The data suggest that the major mode of spread of penicillin-resistant pneumococci in the United States is by clonal expansion and that the most significant components (clones A and B) have been imported into the United States from abroad.

Dissemination of a chloramphenicol- and tetracycline-resistant but penicillin-susceptible invasive clone of serotype 5 Streptococcus pneumoniae in Colombia

A national surveillance conducted in Colombia between 1994 and 1996 identified serotype 5 Streptococcus pneumoniae as the second most frequent cause of invasive disease in children younger than 5 years of age. All 43 serotype 5 isolates collected during this period were shown to be susceptible to penicillin, erythromycin, cefotaxime, and vancomycin, but most (38 of 43, or 88%) were highly resistant to chloramphenicol. In order to clarify a possible genetic relatedness among these isolates, additional microbiological and molecular characterizations were performed. Most (40 of 43, or 93%) of the isolates were found to be resistant to tetracycline. Pulsed-field gel electrophoresis (PFGE) patterns of chromosomal DNAs revealed that all the 43 isolates were closely related and that 38 of the 43 isolates were representatives of a "Colombian clone" of S. pneumoniae isolates which were recovered throughout the 3-year surveillance period from patients in 13 hospitals located in five Colombian cities. Isolates belonging to this Colombian clone were resistant to chloramphenicol and tetracycline, hybridized with the cat and tetM DNA probes in the same 340-kb SmaI fragment, and had identical PFGE patterns after both SmaI and ApaI digestions.