Resistance of Streptococcus pneumoniae to penicillin, erythromycin and third-generation cephalosporins in Seville, Southern Spain

C l i n i c a l M i c r o b i o l o g y a n d I n f e c t i o n , V o l u m e 3 N u m b e r 3, J u n e 1 9 9 7

as our strains were mostly resistant to penicillin, tetracycline, chloramphenicol and erythromycin, whereas, in Portugal, most of the 23F strains were not resistant to erythromycin [3]. There were many isolates of pneumococci with the same PFGE patterns in this study. Also, many of the 19F and 23F isolates showed the same pattern, which has only occasionally been encountered in other countries [8]. The horizontal spread of genetic material conveying resistance increments does not appear extensive, even though pneumococci are naturally transformable organisms [9]. Typically, members of the same clone should share a common serotype, antibiotic resistance profile and PFGE pattern. In this study, nine of 12 type 19F isolates with a C pattern and four of eight type 23F isolates with an L pattern showed the same multiresistance to penicillin, tetracycline, chloramphenicol and erythromycin. Also, five of nine type 23F isolates with a K pattern were multiresistant to penicillin, tetracycline and chloramphenicol. These results suggest that selection and spread of a few resistant clones has been the major cause of the high prevalence of penicillin-resistant strains. Another study in Korea showed that the resistance rate was only slightly lower for the isolates from outpatients [lo], whereas in other countries a much higher resistance rate has been reported in nosocomially acquired than in community-acquired infections [I 1,121. To verify our assumption, further study is required with the strains isolated from normal carriers or from community-acquired infections.

Acknowledgment

This was reported in part at the 7th International Congress of Infectious Diseases, Hong Kong, 1013 June 1996 (poster presentation 60.013). We acknowledge the technical assistance of Ms Yong Jae Kwon and Young Hee Seo.

Yunsop Chong', Kyihngwon h e ' , Xue-Song Xu', Oh Hun Kwon', Jue-Myung Kim', J ~ t g e nHenrichsen3 'Department of Clinical Pathology, Yonsei University College of Medicine, C.P.O. Box 8044, Seoul, Korea; 2Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea; 'Department of Bacteriology, Statens Seruminstitut, Copenhagen, Denmark

References 1. Christianson K. Community-acquired pneumonia. Epidemiologic and clinical considerations. Clin Microbiol Infect 1996; l(Supp1 1): S2-9. 2. Chong Y, Lee K, Kwon O H , Henrichsen J. Capsular types and antimicrobial resistance of Streptococcuspnenmoniae isolated in Korea. EurJ Clin Microbiol Infect Dis 1995; 14: 528-31. 3. vas Pato M W , de Carvalho CB, Tomasz A, Multicenter Study Group. Antibiotic susceptibhty of Streptococcus pneirmoniae isolates in Portugal. A multicenter study between 1989 and 1993. Microb Drug Resist 1995; 1: 59-69. 4. Bannerman TL, Hancock GA, Tenover FC, Miller JM. Pulsed-field gel electrophoresis as a replacement for bacteriophage typing of Staphylococcus aureus. J Clin Microbiol 1995; 33: 551-5. 5. Baquero F. Pneumococcal resntance to p-lactam antibiotics: a global geographic overview. Microb Drug Resist 1995; 1: 115-20. 6. Scott JAG, Hall AJ, Dagan HK, et al. Serogroup specific epidemiology of Streptococcus pneumoniae: association with age, sex, and geography in 7,000 episodes ofinvasive disease. Clin Infect Dis 1996; 22: 973-81. 7. Klugman Kl? Pneumococcal resistance to antibiotics. Clin Microb Rev 1990; 3: 171-96. 8. Tarasi A, Sterk-Kuzmanovic N , Sieradzh K, Schoenwald S, Austrian R, Toniasz A. Penicihn-resistant and multiresistant Streptococcrrspneuutoniae in a pediatric hospital Zagreb, Croatia. Microb Drug Resist 1995; 1: 169-76. 9. Coffey TJ, Dowson CG, Daniel M, Spratt BG. Genetics and molecular biology of p-lactani-resistant pneumococci. Microb Drug Resist 1995; 1: 29-34. 10. Lee HJ, Park JY, Jang SH, Kim JH, Kim EJ, Choi KW. High incidence of resistance to multiple antimicrobials in clinical isolates of Streptococcus pn~umoniaefrom a university hospital in Korea. Clin Infect Dis 1995; 20: 826-35. 11. McDougal LK, Rasheed JK, Biddle JW, Tenover FC. Identification of multiple clones of extended-spectrum cephalosporin-resistant Streptococcus pneumoniae isolates in the United States. Antimicrob Agents Chemother 1995; 39: 2282-8. 12. Marton A. Epideniiology of resistant pneuniococci in Hungary Microb Drug Resist 1995; 1: 127-30.

Resistance of Sfrepfococcus pneumoniae to penicillin, erythromycin and third-generation cephalosporins in Seville, Southern Spain

Clin Microbiol Infect 1997; 3: 382-385 Resistance of Streptococcus pneumoniae to penicillin and third-generation cephalosporins is increasing in many countries, particularly in Spain, where some of the highest incidences of resistance to penicillin and other antimicrobial agents have been described [l]. Both penicillin-resistant (PRP) and -intermediate strains are

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383

less susceptible to other p-lactams than penicillinsusceptible strains [2]. Third-generation cephalosporins have been considered to be an alternative for the treatment of infections caused by PRE? Nevertheless, strains resistant to third-generation cephalosporins have been described and, in sonie cases, therapeutic failures have been observed when these agents were used [3,4]. In this study, the activities of penicillin, cefotaxime, ceftriaxone, erythromycin and vanconiycin against clinical isolates of S. pneumoniae were determined. The incidence of resistance to these agents in our area and the relationship between resistance to third-generation cephalosporins and other agents were also evaluated. Two hundred and twelve S. pneumoniae strains, consecutively isolated from different patients between January 1993 and December 1995 at the University Hospital V. Macarena, Seville, Spain, were studied. The sources of the strains were sputum (84, 39.6%), blood culture (53, 25.0%), bronchial aspirate (23, 10.8%), ocular exudate (19, 9.0%), pleural effusion (9, 4.2%), cerebrospinal fluid (CSF) (4, 1.9%), and others (20, 9.4%). Isolates were identified by standard methods [5]. S. pneumouiae ATCC 49619 arid Staphylococcus aureus ATCC 29213 were used as control strains. Penicillin G (Sigma, USA), cefotaxinie (Hoechst, Germany), ceftriaxone (Sigma, USA), erythroniycin (Sigma, USA) and vanconiycin (Lilly, USA) were used as standard powders of known potency. A microdilution assay using cation-adjusted Mueller-Hinton broth (Difco, USA), supplemented with 5% lysed horse blood (Difco, USA), was used, with incubation at 35°C for 24 h in air. The antimicrobial concentrations evaluated ranged froni 0.03 to 64 pg/mL. Strains were classified as susceptible, intermediate or resistant to penicillin when MIC values were 50.06, 0.125-1, or 2 2 pg/mL, respectively 161. Strains with MICs of cefotaxime or ceftriaxone of 1 pg/mL were considered intermediate, and those with MICs of 2 2 pg/mL resistant to these agents [ 71. Susceptibility categories for erythromycin and vanconiycin were established according to the NCCLS guidelines [6]. Range, MIC;,,, MICso values and percentages of intermediate and resistant strains to the antimicrobial agents evaluated are presented in Table 3 . Considering

penicillin G, 39.2% were intermtdiate and 12.3% were resistant, while 4.2% were resistmt to cefotaxinie and 4.2% to ceftriaxone. Resistance to erythromycin was observed in 27.4% of the strains. N o resistance to vancomycin was observed. The relationship between resistance to thirdgeneration cephalosporins and penicillin resistance is shown in Table 2. All strains rrsistant to cefotaxinie and/or ceftriaxone (10, 4.7%) were also penicillin resistant. Resistant strains always had an MIC of thirdgeneration cephalosporins of 2 pg/niL, except for one strain, for which the MIC of cefotaxinie was 4 pg/mL. One strain was resistant to ceftriaxone (MIC 2 pg/mL) but susceptible to cefotaxime (MIC 0.5 pg/mL). Another one was resistant to cefotaxinie (MIC 2 pg/niL) but susceptible to ceftriaxone (MIC 0.5 pg/mL). Eighteen (8.4%) strains were interniediate to cefotaxime and 23 (9.8%) to ceftriaxone. All of them were also intermediate or resistant to penicillin. O f penicillin-resistant and penicillin-intermediate strains, 57.7% and 43.496, respectively, were resistant to erythromycin. Similarly, 45.5% and 56.5% of cefotaxinie-ceftriaxone-resistant and -intermediate strains, respectively, were resistant to erythromycin. Among the 57 strains isolated froni either blood or CSF, 18 (31.696) and eight (14%), respectively, were intermediate or resistant to penicillin G, and seven (12.3%) and two (3.5%), respectiv,:ly, were intermediate or resistant to third-generation cephalosporins. These values are similar to those obtained for the total strain population studied (see Table 1). There are many studies o n the resistance of S. pneurnoiziae to antimicrobial agents. The different results in those reports led to the recocimendation that each community should develop its own surveillance system to determine the local epideniicdogy of this problem. For this reason, we have studied the resistance of S. pneumoniae to five antimicrobial agents in our area, located in southern Spain. In this study, 12.3'%, of pneumococci were resistant to penicillin. In other areas of Spain, the current prevalence of P R P (MIC of penicillin > I pg/niL) ranges from 10% to 2O'%,, depending on the age of the patients, the geographic area and the origin of the isolates [XI. In other regions

Table 1 Range, MICX and MlCso values (pg/niL) of five antinucrobial agents against S. pneumoniur (212 strains) Kansc l'cnicillin Cefotaximr Crftri~~xonc Erythroniycin Vancornycin

50.03-4 5 0.i13-4 50.03-2

50.03->64 50.03-1

MICoii

94 lnterinediate

0.125

2

0.06

1 1

39.2 8.4 9.8

MICx

0.06 50.03 0.2.5

>63 0.25

4.2 0.0

1%

Ile\l\t.lncc

12.3 4.2 4.2 27.4 0.0

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Table 2 Relationship between susceptibility to penicillin and to cefotaxime-ccfiriaxone among 212 isolates of S. pneumoniae Cefotaxiuie

Cefiriaxone

Intermediate

Resistant

(”/.I

(“/.I

(“w

0.0

0.0 0.0

0.0 5.6

0.0 0.0

4.2

4.2

4.2

Penicillin Susceptible Intermediate Resistant

4.2 4.2

Intermediate

These data were partially presented at the 7th European Congress of Clinical Microbiology and Infectious Diseases, held in Vienna from 26 March to 30th March 1995.

Resistant

Luis Martinez-Martinez Inmaculada Upez-Hernhdez‘, Alvaro Pascual Ana Isabel Suhez2, EvelioJ. Perea ‘Department of Microbiology, School of Medicine, Apdo 914, 41080-Seville, Spain 2Department of Microbiology, University Hospital V. Macarena, Seville, Spain

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of Europe, the prevalence of P R P varies significantly from 0-5% (in Germany, Switzerland and Italy) to 11-1 7% (in France) to around 50% (in Hungary and Romania) [l].Similar variations have been reported in the USA. In one large multicenter study, an overall incidence of 6.6% was reported [9], but the incidence was 61% in Kentucky among isolates from the nasopharynx of children from day-care centers [lo]. The emergence of S. pneumoniae strains intermediate or resistant to third-generation cephalosporins has been recognized in several countries. Considering only resistant strains (MIC 2 2 pg/mL), data range from 0% (Germany) to 2.5% (UK) to 4% (USA) [l]. PhrezTrallero et a1 reported a prevalence of5.2% in northern Spain [ l l ] , a figure similar to that presented in this study (Table 1). The vast majority ofour S. pneumoniae strains intermediate/resistant to third-generations cephalosporins were not susceptible to penicillin as has been previously reported. Resistance to cefotaxime and susceptibility to penicillin has also been described [12], but was not found among our strains. In Spain, Moreno et a1 reported an increasing resistance to erythromycin from 7.6% in 1988 to 15.2% in 1992, particularly in children under 5 years and hospitalized patients [13]. Similar trends have been observed in other European countries and the USA (14,151. In Barcelona (Spain), 13-2494 of S. pneumoniae isolates were resistant to erythromycin [8]. In our study, the resistance to this antimicrobial agent was even higher (27.4%). About one-quarter (25.8%) of erythromycin- resistant S. pneumoniae isolates were also resistant to penicillin, and 8.6% of them were also resistant to third-generation cephalosporins. As has been documented in all published reports, we found no strain resistant to vancomycin.

Acknowledgments

The authors thank P Hidalgo and J. Uawson for preparing the manuscript.

‘p’,

‘j’,

‘ j 2

References 1. Baquero F. I-’neuniococcalresistance to p-lactam antibiotics: a global geographical overview. Microb Drug Resist 1995; 1: 115-20. 2. Liiiares J, Alonso T, P6rez JL, et al. Decreased susceptibility of penicillin-resistant pneumococci to twenty-four plactanis. J Antimicrob Chemother 1992; 30: 279-88. 3. John CC. Treatment failure with use of a third-generation cephalosporin for penicillin- resistant pneumococcal meningitis: case report and revirw. Clin Infect Dis 1994; 18: 188-93. 4. Catalin MJ, Fertiindez JM, Vizquez A, Varela de Seijas E, Suirez A, Bernaldo de Quirbs C. Failure of cefotaxinie in the treatment of meningitis due to relatively resistant Streptococcus pnetmioniae. Clin Infect Dis 1994; 18: 766-9. 5. Kuoff KL. Streptococcus. In Murray PR, Baron EJ, Pfaller MA, Tenover FC, Yolken R H , eds. Manual of clinical microbiology, 6th edn. Washington: American Society for Microbiology 1995: 299-307. 6. National Committee for Clinical Laboratory Standards. Methods for dilution antimicrobial susceptibility test for bacteria that grow aerobically, 3rd edn. NCCLS publication M7-A3. Villanova, Pa: NCCLS. 7. National Committee for Clinical Laboratory Standards. Perforniance standards for antimicrobial susceptibility testing: Fifth International Supplement. NCCLS Document M100S5. Villanova, Pa: NCCLS. 8. Liiiares J, Tubau E Meningitis neuniocbcica y cefalosporina7 de tercera generacibn. EnfInfect Microb Chi 1996; 14: 1-6. 9. Greiinan RE Butler JC, Tenover FC, Elliot JA, Facklam RP. Emergence of drug resistant pneumococcal infections in the United States. JAMA 1994; 271: 1831-5. 10. Morbid Mortal Wkly Rep. Update: Drug-resistant S.P. Kentucky and Tennessee. 1994; 43: 23-5. 11. P6rez-Trallero E, Garcia-Arenzana JM, Montes M, LbpezLopategui C, Cilla G. Increment0 de la resistencia a cefotaxima en Streptococcus pnetimoniae en Guiphzcoa. Estudio de 14 aiios. VI Reunibn Nacional de Enfermedades Infecciosas y Microbiologia Clinica Sitges, Barcelona, 1995. Kesumen 7.9.

Letters t o the Editors

12. Coffey TJ, Daniels M, McDougal K, Dowson CG, Tenover FC, Spratt BF. Genetic analysis of clinical isolates of Streptococcus pneunzoniae with high-level resistance to expandedspectrum cephalosporins. Antiniicrob Agents Cheniother 1995; 39: 1306-13. 13. Moreno S, Garcia-Leoni ME, Cerceriado E, Diaz MD, Bernaldo de Quir6s JCL, Bouza E. Infections caused by erythroniycin-resistant Streptococcus pnrumoniae: incidence, risk-factors, and response to therapy in a prospective study. Clin Infect I l i s 1995: 20: 1195-200. 14. Geslin P, Bun-Hoi A, F r h d u x A, Acar JE Antimicrobial resistance in Streptococcus pneunzoniae: an epidemiological survey in France, 1970-1990. Clin Infect Dis 1992; 15: 95-8. 15. Tarpay MM, Welch DF, Salari H, Marks MI. In vitro activity of dntibiotics coniniody used in the treatment of otitis media against Streptoroccus puruinoniae isolates with different susceptibilitiec to penicillin. Antiniicrob Agents Cheniother 1982; 22: 145-7.

High-level aminoglycoside resistance and glycopeptide resistance among enterococci isolated from blood cultures, 1990-95

Clin iZlicvobio1 Infect 1997; 3: 385-387 Recently enterococci have emerged as increasingly prominent pathogens in nosocomial infections [I]. The standard treatment for serious enterococcal infections is a bactericidal and synergistic combination of a p-lactam antibiotic (ampicillin or benzylpenicillin) or vancoinycin with an aiiiinoglycoside [2]. Unfortunately, during the 1980s, high-level resistance (MIC> 2000 nig/L) of enterococci to aniinoglycosides caused by aminoglycoside-modifying enzymes emerged rapidly, making the treatment of such infections difficult [3]. Since the late 1980s, glycopeptide-resistant enterococci have been reported in many parts of the world [4]. Most reports have described clusters of nosocomial infections 151. N o established therapy exists for lifethreatening diseases caused by such organisms. We previously reported the prevalence of highlevel resistance to aiiiinoglycosides among enterococci isolated from blood cultures submitted to the Laboratorio di Microbiologia e Virologia of the Policlinico Careggi, Florence, Italy, from March 1990 to June 1991 [6]. In that study, we found that 65.2% of Entevococcus .fac.calis strains were highly resistant to gentamicin, 47.8% were highly streptoinicin resistant, and 86.9% were resistant to at least one of the aminoglycosides tested. We have continued monitoring this phenomenon in Florence and we now report data on enterococcal strains isolated from blood cultures updated to the end of 1995. From January 1995 we included the

385

Nuovo Ospedale San Giovanni di L>io of Florence, thus covering all the hospitals in the ]'lorentine area. One hundred and eighty-nine isolates of enterococci from blood cultures performed during 1990-95, one strain per patient, were studied. There were 126 strains of E.faecalis, 46 E. faeciuiir, 12 E. avium, two E. durans, two E. gallinarum, and one E. mundtii. Enterococcal strains were identified and tested for their antimicrobial susceptibility with the automated Vitek system (bioMkrieux, Marcy l'Etoile, France), which includes a screening test for highlevel aminoglycoside resistance, supplemented with 1:ests for motility and pigment production. The results are summarized in Table 1 . The susceptibility card (GPS-TA) utilized from 1990 to 1994 allowed detection of high-level resistance to gentanllcin (500 mg/L) and streptomycin (2000 mg/L). Since January 1995, a different card (GPS-IR) has been used to determine the mtimicrobial susceptibility of enterococci. This card irtcludes a screening test for high-level gentamkin resistaiice only. A inicrotiter broth dilution method was utilized to detect streptomycin resistance and to confirm the resistance data obtained by the Vitek system. Broth microdilution minimum inhibitory concentrations (MICs) of vancomycin and teicoplanin were determined for strains that were shown to be glycopeptide resistant by the Vitek system. P-Lactamase production was tested with the chromogenic cephalosporin nitrocefin. In the last three years there has been a significant decrease in the prevalence of E. ,.faeralis highly resistant to gentamicin, in comparison with the three preceding p<0.05). We did not find any years (chi"4.56; particular explanation for this finding, and the low number of strains calls for caucion in formulating a hypothesis. Smaller variations were observed in streptomycin resistance. Twenty-three of 27 (85.2%) E.j&ralis strains with high-level resistance to gentanllciii isolated in the last three years were also highly resistant to streptomycin. No P-lactamase--producing strains of enterococci were found during the study period. In August 1994, a vancomytzin-resistant E. faeciuin strain (yielded in two blood cultures) was first isolated in Florence from a 46-year-old man with acute rnyeloid leukemia in the hematology unit of Careggi Hospital. In January 1995, a second vaiiconiycin-resistant E . faeciurn strain (yielded in three blood cultures) was recovered from a 74-year-old woman who had undergone an operation for an aneurysm of the left carotid in the neurosurgery unit of the same hospital. Both isolates showed the Van A phenotype: MICs of vancomycin and teicoplaniii were 256 and 32 mg/L, and 256 and 64 nig/L, respectively, for the two strains. Pulsedfield gel electrophoresis (PFGE)--basedrestriction fragment length polymorphism (1)NA RFLP) analysis