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Coagulase-negative staphylococci emerging during teicoplanin therapy and problems in the determination of their sensitivity.

Four strains of coagulase-negative Staphylococcus spp. were isolated from blood cultures taken from two neutropenic patients; in three cases while they were receiving teicoplanin as part of an antimicrobial therapeutic regimen. Results of teicoplanin susceptibility tests carried out on these strains varied according to the technique used. The strains were susceptible by disc-diffusion testing, but the MIC of teicoplanin was 8-16 mg/l, when tested according to the recommendations of the Antibiogram Committee of the French Society of Microbiology, and thus categorized as of intermediate susceptibility. It seems reasonable to avoid using teicoplanin for the treatment of infections caused by coagulase-negative staphylococci until technical problems encountered in the in-vitro determination of susceptibility have been resolved.

Adult↗

Epidemiological typing of klebsiellae with extended-spectrum beta-lactamases from European intensive care units.

Extended-spectrum beta-lactamases (ESBLs) are an increasing cause of resistance to oxyimino-aminothiazolyl cephalosporins, especially in klebsiellae. In a recent survey we detected ESBLs in 220 (23%) of 966 consecutive klebsiellae from 35 intensive care units (ICUs) in southern and western Europe. The present study examined the extent to which this distribution reflected epidemic strain spread, as against the distribution of ESBL genes into unrelated strains. All 220 ESBL producers were subjected to capsular serotyping and pulsed-field gel DNA electrophoresis (PFGE). Beta-Lactamases were typed for strains isolated on three or more occasions, with the emphasis on SHV enzymes, as these were commoner than TEM variants. Serotyping and PFGE typing defined 85 distinct strains, from 23 of the 35 participating centres. Of 14 centres that contributed five or more ESBL producers, all sent representatives of more than one strain, and two centres sent members of ten or more different strains in contributions of 17-21 ESBL-producing isolates. Nevertheless, epidemic strains-defined as those represented by three or more isolates-accounted for a majority (61%) of the collection. Fifty-two isolates of the same serotype K25 (occasionally acapsular) strain with SHV-4 beta-lactamase were recovered at two French hospitals and one in Belgium. This strain has been found by others in France, and has become particularly widespread. Another single strain was found in two separate Portuguese centres, and many individual hospitals had one or more epidemic strain(s), as well as a scatter of diverse ESBL producers. Major variation in antibiogram and plasmid profile was apparent within strains, with some intra-strain variation in beta-lactamase type. These data imply a fluid situation, with resistance determinants being gained, modified or lost. The endemicity of ESBL producers is disturbing since it limits the potential for control by blocking strain spread, while the diversity within strains is disturbing because it complicates the design of antibiotic policies even during 'single strain' outbreaks.

Anti-Bacterial Agents↗

An in-vitro study of the antimicrobial susceptibilities of Yersinia enterocolitica and the definition of a database.

The antibiotic susceptibilities of 151 Yersinia enterocolitica strains isolated from humans, animals and the environment, and belonging to biovars 1A (n = 22), 1B (n = 13), 2 (n = 12), 3 (n = 31), 4 (n = 63) and 5 (n = 10) to 71 antibiotics were examined. Biovars could be characterized phenotypically by their similar antibiograms. For the majority of biovars only minor differences in susceptibilities were detected. Ninety-nine percent of all Yersinia strains were resistant to amoxycillin, but biovar-related differences in MICs were demonstrated. Significant differences, characteristic of specific biovars, were detected for fosfomycin, some beta-lactams (in particular amoxycillin/clavulanate, and ticarcillin). Strains of biovar 1A were resistant or of intermediate susceptibility to ticarcillin and had fosfomycin MICs of 16-64 mg/L and amoxycillin/clavulanate MICs of 4-32 mg/L. Most strains of biovar 1B (n = 11) were sensitive to amoxycillin/clavulanate (MIC = 0.5-2 mg/L). Most strains of biovar 2 (n = 10) showed an antibiotic phenotype resembling that of strains of biovar 1A, but they were more susceptible to fosfomycin (MIC = 4-16 mg/L). Twenty-seven strains of biovar 3 had amoxycillin/clavulanate MICs of 4-32 mg/L; 19 of them were sensitive to ticarcillin and fosfomycin. Biovar 4 strains were uniformly sensitive or of intermediate susceptibility to amoxycillin/clavulanate (MIC = 0.5-4 mg/L), sensitive to fosfomycin (MIC = 1-4 mg/L) but resistant to ticarcillin. The prevailing antibiotic phenotype of biovar 5 (n = 7) was similiar to the phenotype of biovar 4, although these biovar 5 strains were slightly more susceptible to amoxycillin/clavulanate and showed a heterogeneous pattern of susceptibility to fosfomycin (MIC = 1-32 mg/L). The results of this study show that unambiguous statements cannot be made about the natural antibiotic susceptibility to certain beta-lactams and fosfomycin of Y. enterocolitica. The data indicate a complex regulation of beta-lactamases in Y. enterocolitica. Some beta-lactamases are found more frequently or will be expressed predominantly in specific biovars.

Anti-Bacterial Agents↗

Antimicrobial susceptibility of Enterobacteriaceae isolated from vegetables.

There is potential for the normal faecal flora of humans to be augmented by resistant strains of bacteria, acquired from food. The frequency of resistance in the aerobic Gram-negative faecal flora is often very high. The purpose of this study was to find out whether food strains contribute to this resistance. One hundred and thirty-seven vegetable samples were studied, 48 of Finnish origin, and 89 imported. From these samples, 535 different strains of bacteria belonging to the family Enterobacteriaceae were isolated. Enterobacter spp. were most frequent, Escherichia coli was rare. Sensitivity testing was undertaken only for isolates with different biotypes and antibiograms. No resistance was found to cefotaxime, aztreonam, imipenem, gentamicin, nalidixic acid or ciprofloxacin. The frequency of trimethoprim resistance was 0.2%, sulphamethoxazole resistance 1.3%, and tetracycline resistance 5.5%. These frequencies were much lower than those found in faecal flora. Chloramphenicol and cefuroxime resistance was found in 12% and 14% of isolates, respectively. The only statistically significant differences between the Finnish and imported strains were for these two; the Finnish isolates were more resistant to cefuroxime, whereas the imported ones were more resistant to chloramphenicol. Consequently, bacteria from vegetables are not responsible for the high prevalence of resistant Enterobacteriaceae in faecal flora in Finland; they are in fact unusually susceptible to the antibiotics studied. Multiresistance profiles, typical of strains associated with human activities, were not identified in these isolates.

Anti-Bacterial Agents↗

Antibiotic resistance: effect of different criteria for classifying isolates as duplicates on apparent resistance frequencies.

OBJECTIVE: To investigate the effect of screening specimens and different criteria for exclusion of duplicate isolates when surveillance of antimicrobial resistances is performed. MATERIALS AND METHODS: Trends in resistance were analysed for recent isolates of selected organisms from Guy's and St Thomas' Hospitals with the use of various criteria for the exclusion of duplicates, including time since the last isolate and antibiogram pattern, and the effect of excluding screening specimens. RESULTS: There was a significant difference of about 8% in the apparent frequency of methicillin resistance in Staphylococcus aureus in inpatients if the time limit for duplicates was set at 5 rather than 30 days; it was about 10% if a 5 day limit was compared with a 365 day limit. There was also a significant difference, of 6-10%, in apparent resistance frequencies if isolates from screening specimens were excluded. Apparent gentamicin resistance rates in Klebsiella spp. varied between 11% and 28%, and the number of apparent patient isolates of gentamicinresistant organisms varied by up to 35%, depending on the duplicate exclusion criteria chosen. Effects were smaller, though still significant, for vancomycin resistance in Enterococcus spp. There was little effect for amoxicillin or cefuroxime resistance in Escherichia coli isolates from general practitioners, where the proportion of duplicates was small. CONCLUSION: Improved surveillance of antibiotic resistance is needed. However, care needs to be taken in setting the criteria for classifying isolates as duplicates and in comparing results where these criteria may be different or unknown.

Bacteria↗

The OPTAMA programme: utilizing MYSTIC (2002) to predict critical pharmacodynamic target attainment against nosocomial pathogens in Europe.

OBJECTIVES: The Optimising Pharmacodynamic Target Attainment using the MYSTIC (Meropenem Yearly Susceptibility Test Information Collection) Antibiogram (OPTAMA) programme identifies antibiotic regimens with the highest probability of attaining critical pharmacodynamic targets, accounting for the inherent variability in pharmacokinetics, dosages and MIC distributions. METHODS: European MIC data were obtained from the MYSTIC programme. Pharmacodynamic target attainment was calculated by Monte Carlo simulation for meropenem, imipenem, ceftazidime, cefepime, piperacillin/tazobactam and ciprofloxacin against Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii and Pseudomonas aeruginosa. RESULTS: Significant differences in probability of target attainment were found, with Northern Europe demonstrating the highest probabilities of target attainment and Eastern Europe the lowest. The carbapenems had the highest target attainments and susceptibility levels across all regions and pathogens. The cephalosporins demonstrated high target attainments and susceptibility results against E. coli and K. pneumoniae in Northern and Southern Europe. Piperacillin/tazobactam and ciprofloxacin had the lowest levels for both parameters in all regions. Desirable target attainment was not achieved (except for carbapenems in Northern Europe) for A. baumannii and P. aeruginosa; thus, combination therapy may be appropriate empirical therapy for these pathogens in Southern and Eastern Europe. The closest correlations between target attainment and susceptibility were for meropenem 1 g every 8 h, imipenem 0.5 g every 6 h and ceftazidime 1 g every 8 h. CONCLUSIONS: The study highlighted significant overestimations between the probability of target attainment and the reported percentage susceptibility, particularly for piperacillin/tazobactam and ciprofloxacin. The approach of the OPTAMA programme provides a novel tool which complements susceptibility data to help in the selection of appropriate empirical antibiotic therapy.

Acinetobacter baumannii↗

Epidemiology of CAPD-associated peritonitis caused by coagulase-negative staphylococci: comparison of strains isolated from hands, abdominal Tenckhoff catheter exit site and peritoneal fluid.

We identified twenty patients maintained on continuous ambulatory peritoneal dialysis who suffered repeated episodes of peritonitis caused by coagulase-negative staphylococci. We documented hand and exist-site coagulase-negative staphylococcus-associated peritonitis over a total period of 32 months, and compared hand and exit-site strains with strains isolated from dialysate fluid using three typing methods: biotyping using the API Staph kit plus antibiograms, immunoblotting using sera raised in rabbits to three standard strains of coagulase-negative staphylococci, and 35S-methionine-labelled coagulase-negative staphylococcal profiles separated on sodium dodecylsulphate polyacrylamide gel electrophoresis and visualised by autoradiography (radioPAGE). In 5 of 84 episodes, strains isolated from skin were indistinguishable by all three typing methods from the dialysate strain. In a further two episodes, hand or exit-site isolates were indistinguishable by all three typing methods from the dialysate strain isolated in the subsequent, but not the same, episode. Thus in the majority of episodes, no inference of hand or exit-site origin of dialysate infection could be drawn.

Adult↗

Risk factors for wound infections after genitourinary reconstructive surgery.

In January through August 1983, eight children developed wound infections after they underwent genitourinary reconstructive surgery at one hospital. Cultures of purulent drainage yielded Pseudomonas aeruginosa in two cases, Streptococcus faecalis in one case, both S. faecalis and Staphylococcus epidermidis in one case, and S. faecalis and other Gram-negative rods in four cases. A study in which uninfected children who had had genitourinary reconstructive surgery were used as controls revealed that all cases and controls had received cephalosporin prophylaxis. Antibiograms revealed that all organisms were resistant to the cephalosporin antibiotics tested. Risk of infection was associated with shaving (p less than 0.001, Fisher's exact test) and exposure to one nurse (nurse X) (p = 0.003, Fisher's exact test) and one surgeon (surgeon X) (p = 0.007, Fisher's exact test). Nurse X was the private scrub nurse for surgeon X; she was present only at operations surgeon X performed (p less than 0.001, Fisher's exact test) and had no reported or observed practices different from those of other surgical nurses. However, surgeon X had two practices that were notably different from those of other surgeons: 1) he used quaternary ammonium compounds, acetone/alcohol, and 1 per cent hexachlorophene for preoperative skin preparation; and 2) he prepared the operative site himself. In addition, he was observed to prepare the operative site by beginning centrally, moving peripherally, and returning to the central area with the same sponge. These findings suggested that the shaving of the operative site and the use of certain agents and/or different preparatory techniques may have contributed to increased risk of wound infections. These wound infections were caused by organisms resistant to the prophylactic antibiotic(s) used.

Anti-Bacterial Agents↗

Vertebral osteomyelitis due to Staphylococcus epidermidis.

Vertebral osteomyelitis due to Staphylococcus epidermidis is extremely rare and usually occurs in the context of immunosuppression in association with an adequate portal of entry for infection. This paper reports a case of vertebral osteomyelitis due to S. epidermidis in a man with no evidence of immunosuppression or obvious portal of entry. The patient presented with severe back pain but there were no clinical signs of infection. Radiographs and computerized tomographs showed destruction of thoracic vertebral bodies and an adjacent soft tissue mass. S. epidermidis was grown from multiple blood cultures. All isolates had identical antibiograms and biochemical profiles. There was evidence of healing of the vertebral bodies and resolution of the soft tissue mass after appropriate antistaphylococcal treatment.

Aged↗

Non-typhoidal salmonella bacteraemia among HIV-infected Malawian adults: high mortality and frequent recrudescence.

OBJECTIVE: Non-typhoidal salmonella (NTS) bacteraemia is a common, recurrent illness in HIV-infected African adults. We aimed to describe the presentation and outcome of NTS bacteraemia, the pattern of recurrence, and to determine whether recurrence results from re-infection or recrudescence. DESIGN: One hundred consecutive adult inpatients with NTS bacteraemia in Blantyre, Malawi, were treated with chloramphenicol. Survivors were prospectively followed to detect bacteraemic recurrence. METHODS: Index and recurrent isolates were typed by antibiogram, pulsed-field gel electrophoresis and plasmid analysis to distinguish recrudescence from re-infection. RESULTS: Inpatient mortality was 47%, and 1-year mortality was 77%. A total of 77 out of 78 cases were HIV positive. Anaemia was associated with inpatient death, and several features of AIDS were associated with poor outpatient survival. Among survivors, 43% (19/44) had a first recurrence of NTS bacteraemia at 23-186 days. Among these, 26% (5/19) developed multiple recurrences up to 245 days. No recurrence was seen after 245 days, despite follow-up for up to 609 days (median 214). Suppurative infections were not found at presentation, and were only seen twice at recurrence. Index and recurrent paired isolates were identical by phenotyping and genotyping, consistent with recrudescence, rather than re-infection. CONCLUSION: NTS bacteraemia has a high mortality (47%) and recurrence (43%) rate in HIV-infected African adults. Recurrence is caused by recrudescence rather than re-infection. As focal infections were rarely found, recrudescence may often be a consequence of intracellular tissue sequestration. There is an urgent need for improved primary treatment and secondary prophylaxis in Africa.

Adult↗

The microbiology laboratory's role in life-threatening infections.

The microbiology laboratory's contribution to the care of patients who are critically ill is explored. The economic and epidemiologic impact of broad-spectrum antibiotic use is discussed, along with methodology of antimicrobial susceptibility testing and the potential value of an antibiogram. The clinical benefits of blood, sputum, urine, spinal fluid, and wound cultures are discussed, with an emphasis on interpretation of culture results. The significance of, and procedures for, proper specimen collection are emphasized throughout the article, and the ramifications of improper specimen collection are presented.

Bacterial Infections↗

The epidemiology of methicillin-resistant Staphylococcus aureus in a burn center.

The emergence of methicillin-resistant Staphylococcus aureus (MRSA) in a critical care facility creates a multifaceted epidemiological problem in uncovering the source of infection. This study was undertaken to determine the true etiology of MRSA burn wound infections. Patients with a 30% or greater TBSA burn had both burned and unburned skin surface cultured upon admission, using RODAC plates. All other body fluids were cultured when sepsis was suspected. Admission cultures of 14 patients who developed MRSA wound infections were examined for methicillin-resistant organisms. Both admission isolates and infection isolates were compared by antibiogram analysis. Of the 14 patients admitted who developed MRSA infections, 57.1% of these had methicillin-resistant staphylococci present on admission. However, the remaining 42.9% of the patients had methicillin-sensitive, B-lactamase positive staphylococci present on admission. Isolates of group D streptococci resistant to methicillin were isolated in 35.7% of the patients. This data suggests that burn wound infections caused by MRSA very likely arise from the endogenous flora present at the time of injury through conferring the resistant plasmid by conjugational transfer.

Burn Units↗

Incidence and susceptibility of pathogenic bacteria vary between intensive care units within a single hospital: implications for empiric antibiotic strategies.

BACKGROUND: The purpose of this study was to determine whether the incidence of recovery and patterns of antibiotic susceptibility of pathogenic bacteria vary between intensive care units (ICUs) in a single teaching hospital. METHODS: Culture and susceptibility results were collected prospectively for a 3-month period (April through June 1999) in each of the surgical, trauma, and medical ICUs. The number of unique isolates and susceptibility patterns were determined. Susceptibility of isolates among ICUs was compared with chi2. RESULTS: Statistically significant differences between ICUs in susceptibility to various antibiotics were found for Staphylococcus aureus, Enterococcus sp, Acinetobacter sp, Enterobacter sp, Klebsiella sp, and Pseudomonas sp. Notably, vancomycin-resistant Enterococcus was not seen in the medical ICU, whereas it was seen in both the surgical and trauma ICUs. Klebsiella spp resistant to ceftazidime were seen only in the trauma ICU. The aminoglycosides and quinolones had attenuated activity against Pseudomonas sp in the surgical ICU, whereas they remained highly effective in the trauma ICU. Cefazolin had no activity against the Enterobacter sp in either of the surgical ICUs, but was highly effective in the medical ICU. CONCLUSION: Although the microbiologic results of this study should not be extrapolated to other institutions, the principle is of value. There is variability between ICUs in a single large teaching hospital in susceptibility of bacterial pathogens to various antibiotics. This may have implications in the design of empiric antibiotic strategies and the planning of the hospital formulary. Hospital wide or composite ICU antibiograms are inadequate for planning empiric therapy in the ICU.

Antibiotic Prophylaxis↗

The prevalence of high-level methicillin resistance in multiply resistant hospital staphylococci.

This study was prompted by observing in the summer of 1975, five lethal septicemias caused by methicillin resistant staphylococci. Among the 17 initial S. aureus strains, only 36% were killed at 250 micrograms per ml of methicillin. One phage type of S. aureus predominated (85, group III). Methicillin resistance was found in 17 of 102 S. aureus and in 28 off 102 S. epidermidis septicemias; the mortality among methicillin resistant S. aureus cases was 52.9%, corresponding to 39.3% for S. epidermidis sepsis. Antibiograms revealed methicillin resistance in 59/400 S. aureus and 94/400 S. epidermidis isolates. Cross-resistance to other drugs was common. It is concluded that the emergence of methicillin and gentamicin-tobramycin resistance among hospital staphylococci represents a serious, persistent problem. Certain microbiologic characteristics of these resistant strains differ from results heretofore reported by others.

Cephalosporins↗

Long term epidemiological analysis of Citrobacter diversus in a neonatal intensive care unit.

A prolonged outbreak of Citrobacter diversus central nervous system infection among hospitalized term infants, peaking in 1979, ceased with establishment of nurse-patient cohorting. The outbreak was attributed to dissemination of an epidemic strain among infants in an antiquated neonatal intensive care unit. When C. diversus colonization recurred within the new neonatal intensive care unit in 1984, cohorting and bacteriologic surveillance were reinstituted. By utilizing biotypes, plasmid profiles and antibiograms, four different C. diversus strains were identified circulating during 1979. Strains recovered between 1984 and 1988 from neonatal intensive care unit infants were similar to those from community-acquired sources. A strain considered avirulent in 1979 was found causing bacteremia in two infants (one with central nervous system disease) in 1984 to 1988. During cohorting C. diversus acquisition was 0.019/patient-month; after cohorting ceased it was 0.017/patient-month. Multiple source introductions appeared to occur with different C. diversus strains, some causing infant disease. No efficacy of cohorting was evident.

Citrobacter↗

Dynamics of pneumococcal nasopharyngeal colonization during the first days of antibiotic treatment in pediatric patients.

BACKGROUND: Nasopharyngeal (NP) carriage of antibiotic-resistant Streptococcus pneumoniae was shown to be associated with recent antibiotic treatment. To date no studies have evaluated early dynamics of pneumococcal NP carriage during antibiotic treatment. OBJECTIVES: To observe changes in NP pneumococcal carriage within 3 to 4 days after initiation of antibiotic treatment in acute otitis media (AOM). METHODS: Patients ages 3 to 36 months with AOM treated with various antibiotics were prospectively followed. Nasopharyngeal culture for S. pneumoniae was obtained before (Day 1) and 72 to 96 h after initiation of treatment (Days 4 to 5). Antibiogram and serotyping were performed in all isolates as was also the MIC of penicillin. The disappearance and persistence of the initial isolates as well as the appearance of isolates with new serotype or with new antibiotic susceptibility patterns were investigated. RESULTS: A total of 120 patients were studied: 106 received beta-lactam antibiotics and 14 received azithromycin. Among the initial 76 pneumococcal isolates 63, 37 and 13% were resistant to > or =1, > or =2 and > or =3 antibiotic drugs. After 3 to 4 days of treatment with various beta-lactam drugs, 45, 63 and 100% of isolates with MIC values of <0.1 microg/ml, 0.125 to 0.25 microg/ml and 0.38 to 1.0 microg/ml, respectively, persisted in the NP (P = 0.038). There was a difference between the various beta-lactam drugs in their effect on NP colonization: a drug with lower MIC values (cefuroxime-axetil) had a better eradication rate of penicillin-susceptible organisms than a less active one (cefaclor), but neither significantly reduced carriage of penicillin nonsusceptible isolates. Azithromycin eliminated carriage of macrolide-susceptible organisms but increased the carriage of macrolide-resistant ones. In 19 of 120 (16%) patients a new S. pneumoniae isolate was recovered 3 to 4 days after initiation of treatment. Of those 16 (84%) were resistant to the drug the patient was receiving. CONCLUSION: A rapid selection of nonsusceptible NP pneumococcal isolates during antibiotic treatment for AOM is common. This phenomenon may contribute to the spread of resistant pneumococci.

Acute Disease↗

Trends in resistance of Neisseria gonorrhoeae to antimicrobial agents in the United States.

Resistance of Neisseria gonorrhoeae to antimicrobial agents is increasing in the United States. The number of cases of gonorrhea caused by beta-lactamase-producing strains of N. gonorrhoeae (PPNG) increased for the second consecutive year, and 16,608 were reported in 1986; these accounted for greater than 1.6% of all cases of gonorrhea. PPNG is endemic in Florida, New York City, and Los Angeles, and these areas may serve as foci for spread of PPNG strains in the United States. In 1985 N. gonorrhoeae strains that exhibited high-level resistance to tetracycline (TRNG; MIC, greater than or equal to 16.0 micrograms/ml) were reported. Tetracycline resistance was due to the tetM determinant in a 25.2-MDa tetM-conjugative plasmid. The prevalence of TRNG infections was greater than 4% in at least two communities. Strains with chromosomally-mediated resistance to several antimicrobial agents have been isolated more often; 399 cases were reported during the first half of 1986. Spectinomycin-resistant strains have been isolated in several cities, and strains with decreased susceptibility to ceftriaxone have been isolated. Phenotypic characterizations of strains of N. gonorrhoeae by auxotype and serovar, plasmid content, and antibiograms have permitted more detailed study of the heterogeneity and dynamics of strain populations. Characterization of outbreaks caused by resistant strains and surveillance of regional and temporal changes in antimicrobial resistance in gonococcal strain populations may be used in design of innovative strategies for gonorrhea control and for making anticipatory changes in recommended therapies for gonorrhea.

Anti-Bacterial Agents↗

Tetracycline-resistant Neisseria gonorrhoeae. Characteristics of patients and isolates at a London Genitourinary Medicine Clinic.

OBJECTIVES: To compare auxotypes, serovars, and antibiograms of tetracycline-resistant Neisseria gonorrhoeae (TRNG) and non-TRNG isolated from patients attending an East London Genitourinary Medicine (GUM) Clinic. To obtain plasmid profiles for penicillinase-producing gonococci (PPNG) as well as presumptive TRNG. To identify differences in patient characteristics for the TRNG and non-TRNG patient groups. STUDY DESIGN: Gonococcal isolates were collected from 400 patients attending the GUM clinic at the Royal London Hospital GUM Clinic over a 1-year period. Isolates (378) were tested for susceptibility to various antibiotics, auxotyped, and serotyped. Plasmid profiles were obtained for PPNG and isolates exhibiting high-level tetracycline resistance (TRNG). The presence of the tet M determinant was confirmed using the polymerase chain reaction (PCR). The PCR product was digested with the restriction endonuclease (RE) Hpa II and electrophoresed on a 2.5% agarose gel to determine an "RE pattern." Patient data were collected by retrospective case-note review. RESULTS: TRNG (n = 42) accounted for 11% of the 378 isolates tested, and the remaining 336 (89%) isolates were non-TRNG. Non-requiring auxotrophy and P1B-2 serovar expression occurred more frequently among TRNG. PPNG accounted for 31% of TRNG and 5% of non-TRNG. Chromosomal resistance to penicillin (CMRNG) was absent among TRNG but accounted for 11% of non-TRNG. One TRNG isolate showed decreased susceptibility to ciprofloxacin (MIC 0.25 mg/l). All isolates were sensitive to cefotaxime, cefixime, spectinomycin, and azithromycin. All TRNG possessed the 25.2 MDa plasmid and produced a PCR product of appropriate size after tet M gene sequence amplification. RE digests of the PCR product gave a single pattern. None of the TRNG in contrast to 18% of the non-TRNG were acquired homosexually. Ethnic distribution differed between the patients with TRNG and patients without non-TRNG (Afro-Caribbean 81% versus 58%; white 19% versus 36%). Most TRNG were acquired in the United Kingdom. CONCLUSIONS: TRNG differ from the non-TRNG in their auxotype and serovar distribution. PPNG are more common among the TRNG isolates, whereas CMRNG appear absent. TRNG are isolated more commonly from Afro-Caribbean patients and were not represented among homosexually acquired isolates.

Adolescent↗