Bacterial resistance to ciprofloxacin in Greece: results from the National Electronic Surveillance System. Greek Network for the Surveillance of Antimicrobial Resistance

Kinetics of bactericidal potency with synergistic combination of allicin and selected antibiotics

Synergistic therapy against the resurgence of bacterial pathogenesis is a modern trend for antibacterial chemotherapy. The phytochemical allicin, found in garlic extract is a commendable antimicrobial agent that can be used in synergistic combination with modern antibiotics. Determination of optimal antibacterial combination for the target species is vital for maximizing efficacy, lowering toxicity, total eradication of the bacterial cells and minimization of the risk of resistance generation. In this present investigation, Hill function-based pharmacodynamics models were employed to elaborate various time-kill kinetics parameters. The bactericidal potency of the synergistic combinations of allicin and individual antibiotic was assessed in comparison to their monotherapy application viz. using sole allicin and sole antibiotics (levofloxacin, ciprofloxacin, oxytetracycline, rifaximin, ornidazole and azithromycin) on actively growing Bacillus subtilis and Escherichia coli bacteria. Here, all the synergistic combinations showed significantly better (t-test p-value < 0.05) killing effect and biofilm reduction potential compared to their respective monotherapy application, where the highest killing effect was observed with rifaximin-allicin combination (kill rate was more than 5.5 h^-1). Moreover, the average inhibition potential to protein denaturation by the synergistic combination group was significantly higher (3.4 fold) than the sole antibiotic's group manifests reduction in the dose-related toxicity. The potential of synergism between antibiotics and allicin combination demonstrated greater killing efficiency at significantly lower concentration compared to monotherapy with increased kill rates in all cases.

Risk factors assessment for nasal colonization of Staphylococcus aureus and its methicillin resistant strains among pre-clinical medical students of Nepal

BACKGROUND

Staphylococcus aureus (S. aureus), a normal flora of nasal cavity, can cause minor to life threatening invasive diseases and nosocomial infections. Methicillin resistant strains of S. aureus are causing a great challenge for treatment options. Therefore, the purpose of this study was to assess the nasal carriage rate of S. aureus, its methicillin resistant strains and risk factors in medical students prior to clinical exposure.

METHODS

The bacterial growth of S. aureus from nasal swab culture was identified by using standard microbiological methods recommended by American Society for Microbiology. Modified Kirby-Bauer disk diffusion method was used for antibiotic susceptibility testing and methicillin resistance was confirmed using cefoxitin and oxacillin disks. D-zone test method was used to determine the inducible clindamycin resistance.

RESULTS

Among 200 participants, nasal carriage of S. aureus was detected from 30 (15%) subjects. Upper respiratory tract infections significantly (P < 0.05) contributed the carriage of S. aureus and their methicillin resistant strains. All of the isolates were reported to be susceptible to vancomycin and teicoplanin. S. aureus strains detected from 8 (4%) students were confirmed to be methicillin resistant.

CONCLUSIONS

The result of our study demands for strict policy to screen all the students for nasal carriage of S. aureus and its MRSA strains to minimize the transmission of this organism from community to hospital settings.

Prevalence of Nosocomial Infections After Surgery in Greek Hospitals: Results of Two Nationwide Surveys

Objective:

To determine the frequency and type of nosocomial infections (NIs) (especially surgical-site infections [SSIs]), risk factors, and the type and duration of antibiotic use among surgical patients in Greek hospitals.

Design:

Two point-prevalence studies.

Setting:

Fourteen Greek hospitals.

Patients:

Those in the hospitals during two prevalence surveys undergoing surgery during their stay.

Results:

In the 1999 survey, 129 of 1,037 surgical patients had developed 148 NIs (14.3%). A total of 1,093 operations were registered, and 49 SSIs (4.5%) were found. In the 2000 survey, 82 of 868 surgical patients had developed 88 NIs (10.1%). A total of 902 operations were registered, and 38 SSIs were detected (4.2%). The median length of stay (LOS) for surgical patients without SSI was 10.0 days (range, 1-19 days); for patients who developed SSI it was 30 days (range, 1-52 days; P < .001). The median LOS prior to surgery for patients without SSI was 1 day (range, 0-4 days); for patients who developed SSI it was 3 days (range, 0-7.5 days; P < .001). Among 30 possible risk factors studied, wound class, LOS prior to surgery, and central venous catheterization were independent predictors of SSI. Median durations of prophylactic antibiotic therapy were 4 days (range, 1-14 days) and 6 days (range, 1-16 days) in the 1999 and 2000 surveys, respectively.

Conclusion:

Surgical patients in Greek hospitals suffered higher rates of SSI than did surgical patients in other developed countries while prophylactic antibiotics were used excessively.

Ciprofloxacin-resistant Escherichia coli isolated from the intestinal microbiota of goats in Greece in the absence of selective pressure

The presence of ciprofloxacin resistance commensal Escherichia coli (C-R-Ec) was determined for goats in the absence of selective pressure in Northern and Central Greece. The C-R-Ec was categorized in 3 groups with respect to their phenotypic resistance to other antibiotics as well as the carriage of antibiotic resistance genes. The first group consisted of 7 C-R-Ec that were found also resistant to tetracycline. Among them tet(B) (n = 7), qnr(S) (n = 7), and qnr(B) (n = 3) producers were identified by polymerase chain reaction. The second group consisted of 10 C-R-Ec that were found sensitive to all other antibiotics, and their phenotypic resistance to ciprofloxacin was not attributed to the presence of resistance genes. Finally, the third group consisted of 2 C-R-Ec also resistant to sulfamethoxazole. These strains were not carrying any transferable elements that contribute to resistance either to ciprofloxacin or to sulfamethoxazole. This is the first report of ciprofloxacin-resistant E. coli isolated from goats in Greece.

Intensive care unit-acquired urinary tract infections in patients admitted with sepsis: etiology, risk factors, and patterns of antimicrobial resistance

OBJECTIVES

The objective of the present study was to evaluate the etiology, risk factors, and patterns of antimicrobial resistance of intensive care unit (ICU)-acquired urinary tract infections (UTIs) in patients admitted with sepsis.

METHODS

In this observational study, 100 septic patients hospitalized in a general ICU were selected. Demographic, clinical, and outcome data were obtained by chart review. Antibiotic resistance/susceptibility was determined using the minimal inhibitory concentration (MIC) technique.

RESULTS

A UTI was present in 28 (28%) patients; the male to female ratio was 19:9 and the mean age of the patients was 58.71+/-19.45 years. From the total of 28 isolates, 27 were resistant to ciprofloxacin, 23 to amikacin, 27 to meropenem, 28 to cefepime, 26 to ceftazidime, and 27 to ceftriaxone.

CONCLUSIONS

On the basis of our results, the rate of multidrug-resistant UTIs may be very high in some ICUs in patients admitted with sepsis. This antimicrobial susceptibility/resistance should be determined, and a special antimicrobial treatment protocol should be planned based on the results for each ICU. The use of antibiotics for treating UTIs should be guided only through this protocol because of the different spectra of pathogens and susceptibility patterns in each ICU.

[Comparative susceptibility evolution in Escherichia coli from urinary tract infections in outpatients and inpatients at Perpignan hospital in 2002 and 2004]

The medical emergency ward makes a link between outpatients and hospitalized ones, so we can study community bacterial ecology. The antibiotic susceptibility in Escherichia coli strains isolated from urinary tract infections (UTI) of patients consulting at emergency ward of our hospital in 2002 and 2004 was determined and compared with the susceptibility of the same strains isolated from UTI of hospitalized patients on the same period. The antibiotic susceptibility was performed with Microscan (Dade Behring). All bacteria were tested against the following antimicrobial agents: amoxicilline (Amx), l'amoxicilline+clavulanic acid (AMC), nalidixic acid (NA), ciprofloxacine (Cip), cotrimoxazole (SXT), nitrofurantoin (Ft). Susceptibility in E. coli strains isolated from outpatients vary from 58 to 54% for Amx, from 88 to 83% for NA, from 96 to 89% for Cip, from 82 to 79% for SXT, from 94 to 96% for Ft and remains at 60% for AMC from 2002 to 2004. Susceptibility in E. coli strains isolated from hospitalized patients vary from 52 to 47% for Amx, 55 to 53% for AMC, from 79 to 70% for NA, from 87 to 79% for Cip, from 74 to 69% for SXT, from 93 to 92% for Ft. Susceptibility in E. coli strains isolated in the community from UTI outpatients is decreasing and it becomes worrying particularly concerning the fluoroquinolones, therefore empiric treatment of pyelonephritis by fluoroquinolones must be assessed again.

Treatment of uncomplicated urinary tract infections in an era of increasing antimicrobial resistance

In the past few years, notable advances have occurred in our understanding of the epidemiology and clinical importance of drug resistance among uropathogens that cause uncomplicated urinary tract infections (UTIs) or cystitis. Guidelines recommend trimethoprim-sulfamethoxazole for empirical treatment of uncomplicated UTI unless trimethoprim-sulfamethoxazole resistance in a community exceeds 10% to 20%. The rationale for this 10% to 20% cutoff appears to be related to clinical and economical considerations and to concerns about the emergence of fluoroquinolone-resistant bacteria. In patients with uncomplicated UTIs caused by uropathogens resistant to trimethoprim-sulfamethoxazole who were treated with this drug combination, clinical outcomes were clarified recently and found to be suboptimal (<60% clinical cure). Following guidelines for empirical treatment of uncomplicated UTIs is problematic. Surveillance of antimicrobial resistance among uropathogens that cause uncomplicated UTIs is performed rarely. Hospital antibiograms provide data on resistance among bacteria that cause community-associated UTIs; however, antibiograms overestimate drug resistance among uropathogens that cause UTIs and may mislead clinicians about the prevalence of local resistance. We review options for management of uncomplicated UTIs in light of these considerations.

Quinolone resistance among Escherichia coli strains from community-acquired urinary tract infections in Greece

Susceptibility data for 10 049 Escherichia coli isolates derived from community-acquired urinary tract infections in Greece during the period January 2000 to June 2002 indicated 8.1% resistance to nalidixic acid and 36% resistance to ciprofloxacin. In a sample of 170 E. coli isolates, mutations in gyrA (25 isolates) and parC (15 isolates) were consistent with the levels of resistance to quinolones. Previous exposure to quinolones and underlying chronic disease were independent risk factors for infection by quinolone-resistant E. coli strains.

Prevalence of bacterial pathogens in infected wounds in a tertiary hospital, 1995-2001: any change in trend?

BACKGROUND

Wound care is a very important aspect of surgical care. Knowledge of the epidemiology of bacterial pathogens associated with infected wounds is critical in formulating policies on infection control.

OBJECTIVE

To determine the prevalence of bacterial pathogens in wounds from various units of a Nigerian tertiary hospital orthopedics and traumatology department, as well as changes over time, if any, in the prevalence rates.

METHODS

A retrospective study was conducted using laboratory records from 1995 to 2001.

RESULTS

670 bacterial isolates from 629 patients were studied. The most common isolates were Pseudomonas spp.-29.9%, and Staphylococcus aureus (S. aureus)--27.5%. Others were Klebsiella spp.-18.5%, Proteus spp.--15.1%, and Escherichia coli (E. coli)--7%. The least common were Streptococci--2%, and Enterococci--0.3%. Pseudomonas spp. accounted for 33% of isolates in the adult wards, while S. aureus was 21% and E. coli 8%. The pattem is similar in the pediatric ward (33.9%, 23.7%, and 8.5%, respectively) and Intensive Care Unit (ICU) (40%, 6.7%, and zero, respectively). S. aureus was the most common isolate from the orthopedic clinics (OPD) 40%, and the A&E (35%), followed by pseudomonas spp.-25.4% and 19%, respectively. The odds of a wound being infected with Gram-negative bacilli among inpatients compared with outpatients is 2.44 (95% CL = 1.72-3.47; P = 0.0000003) Between 1995 and 2001, the prevalence of Gram-positive bacteria decreased, while that of Gram-negative bacilli increased. The prevalence of Pseudomonas spp. and S. aureus also increased.

CONCLUSION

Wounds from patients in the orthopedics and trauma services are more frequently infected with Gram-negative bacilli than by Gram-positive bacteria. The prevalence of the former is higher in the ICU and least in the OPD. Pseudomonas spp. was the most common isolate. It was more common among inpatients, while S. aureus was more common among outpatients. The prevalence of Pseudomonas spp. in particular and Gram-negative bacilli in general is increasing.

Relationship between nosocomial Acinetobacter species occurring in two geographical areas (Greece and the UK)

Fifty-two isolates of Acinetobacter spp. obtained from three Greek and one UK hospital, were studied using partial 16 S ribosomal DNA sequence analysis, repetitive extragenic palindromic sequence-based polymerase chain reaction (REP-PCR) mediated fingerprinting and DNA macro-restriction analysis. The aim was twofold: first, to discern the major differences in the population of Acinetobacter spp. between the two countries. Second, to compare a simple PCR-based typing scheme with pulsed-field gel electrophoresis (PFGE). The multi-resistant Greek isolates were within DNA groups 2 and TU13, and clustered into three types both by REP-PCR and PFGE. By contrast, the more susceptible Oxford isolates were heterogeneous on 16 S RNA sequence analysis and distinguishable on typing. The need for studies that elucidate the phylogeny of Acinetobacter spp. inside and outside hospitals are important, as this will help clarify the relationship between organisms that are increasingly recognized as causes of severe infections.

[Evolution of susceptibility of aerobic gram-negative aerobic bacilli to quinolones and fluoroquinolones in a university hospital (1992-2000)]

Susceptibility to quinolones of aerobic gram-negative bacilli was assessed in a 2000-bed university hospital from 1992 to 2000. There was a significant downward trend in the rate of susceptibility to nalidixic acid (Nal) for Enterobacteriaceae as a whole from 1992 to 2000 (86% vs 82%), and E. coli (92% vs 84%), and an upward trend for K. pneumoniae (74% vs 82%), the latter being related to the control of the spread of epidemic ESBL producing strains. The overall susceptibility of Enterobacteriaceae to ciprofloxacin (Cip) paralleled the susceptibility to Nal: decreased susceptibility for Enterobacteriaceae as a whole (96% vs 89%) and E. coli (99% vs 91%). A clear decrease in the level of susceptibility to Cip occurred during the study period among the Nal-resistant strains as demonstrated by the decrease in the median zone diameter (D) observed among the Nal-resistant strains of E. coli (26 mm in 1992 vs 19 mm in 1998-2000). The zone diameter distribution pattern changed from an unimodal distribution in 1992 to a trimodal distribution in 2000 secondary to the occurrence of a population of resistant strains (D = 13 mm) and of a highly resistant population (D = 6 mm). Finally, the susceptibility to Cip of P. aeruginosa strains remained stable around 62% throughout the study period.

Susceptibility to fluoroquinolones among commonly isolated Gram-negative bacilli in 2000: TRUST and TSN data for the United States. Tracking Resistance in the United States Today. The Surveillance Network

From January to May 2000, as part of the Tracking Resistance in the United States Today (TRUST) surveillance initiative, clinical isolates of Enterobacteriaceae (n=2519) and non-fermentative Gram-negatives (n=580) were prospectively collected from 26 hospital laboratories across the United States. Isolates were tested for susceptibility to three fluoroquinolones (ciprofloxacin, levofloxacin, gatifloxacin) and seven other agents. In addition, data for the same period were collected from The Surveillance Network (TSN) Database-USA, an electronic surveillance network that receives data from more than 200 laboratories in the US. Both surveillance methods produced similar results. Against isolates of Enterobacteriaceae, imipenem was the most active agent, followed by the fluoroquinolones; > or = 86.7% of isolates of all species of Enterobacteriaceae except Providencia spp. were susceptible to fluoroquinolones by TRUST and TSN surveillance. TRUST identified differences in susceptibility to the three fluoroquinolones of > or = 2% for Citrobacter spp., Enterobacter cloacae, Proteus mirabilis and Serratia marcescens. Isolates of P. mirabilis were considerably more susceptible to levofloxacin (94.0%) than to ciprofloxacin (87.7%) and gatifloxacin (87.7%). Other results from TRUST included Pseudomonas aeruginosa being slightly more susceptible to ciprofloxacin (73.5%) and levofloxacin (73.0%) than gatifloxacin (71.0%). Imipenem was the only compound with significant activity (95.1% susceptible, TRUST; 87.4% susceptible, TSN) against Acinetobacter baumannii, but it was inactive against Stenotrophomonas maltophilia. S. maltophilia isolates were more susceptible to levofloxacin and gatifloxacin (77.7-79.8%) than ciprofloxacin (29.7-33.0%). Against 513 urinary isolates of Escherichia coli in TRUST, levofloxacin, gatifloxacin and ciprofloxacin were equipotent. Age and gender had no clear effect on the activity of levofloxacin, ciprofloxacin or gatifloxacin. Similar results for all three fluoroquinolones were seen in outpatients and inpatients. TRUST and TSN data indicated that resistance rates had not changed appreciably for any compound studied since a similar study conducted in 1999. TRUST centralized in vitro and electronic (TSN) surveillance methods provided an effective strategy for monitoring trends in resistance.

Trends in quinolone susceptibility of Enterobacteriaceae among inpatients of a large university hospital: 1992-98

OBJECTIVES

To assess trends in quinolone susceptibility of Enterobacteriaceae isolated in a large university hospital.

METHODS

Between 1992 and 1998, bacterial isolates were collected each year during a 3-month period to evaluate annual changes in susceptibility. In addition, the activities of fluoroquinolones (pefloxacin, norfloxacin, ofloxacin, ciprofloxacin) against nalidixic acid-resistant strains were determined by disk diffusion and MIC methodologies during the first and last year of the study.

RESULTS

The susceptibility of Enterobacteriaceae to nalidixic acid was unchanged between 1992 and 1998 (86% versus 85%). However, at the species level, the susceptibility rates to nalidixic acid decreased for Escherichia coli from 92% to 89%, and for Enterobacter cloacae from 87% to 82%. In contrast, there was a 10% increase in the nalidixic acid susceptibility rates for Klebsiella pneumoniae (74% versus 83%), which was thought to be due to the control of the spread of epidemic extended-spectrum beta-lactamase (ESBL)-producing strains. The overall susceptibility of the Enterobacteriaceae to the fluoroquinolones remained high during the study period, greater than 90% in the case of ciprofloxacin. However, nalidixic acid-resistant Escherichia coli showed decreased susceptibility to ciprofloxacin between 1992 and 1998, as reflected by a decrease in median zone diameter (26 mm to 19 mm), an increase in MIC(50) (0.25 mg/L to 1 mg/L) and a shift in MIC distribution (unimodal in 1992 to bimodal in 1998). This has resulted in the reduced susceptibility of Escherichia coli to fluoroquinolones between 1992 and 1998 (pefloxacin, 95-90%; ciprofloxacin, 99-95%).

CONCLUSIONS

The susceptibility of Escherichia coli to quinolones has decreased, and the level of susceptibility of the resistant strains has increased over the 7-year study period.

Evaluation of current activities of fluoroquinolones against gram-negative bacilli using centralized in vitro testing and electronic surveillance

Given the propensity for Enterobacteriaceae and clinically significant nonfermentative gram-negative bacilli to acquire antimicrobial resistance, consistent surveillance of the activities of agents commonly prescribed to treat infections arising from these organisms is imperative. This study determined the activities of two fluoroquinolones, levofloxacin and ciprofloxacin, and seven comparative agents against recent clinical isolates of Enterobacteriaceae, Pseudomonas aeruginosa, Acinetobacter baumannii, and Stenotrophomonas maltophilia using two surveillance strategies: 1) centralized in vitro susceptibility testing of isolates collected from 27 hospital laboratories across the United States and 2) analysis of data from The Surveillance Network Database-USA, an electronic surveillance network comprising more than 200 laboratories nationwide. Regardless of the surveillance method, Enterobacteriaceae, P. aeruginosa, and A. baumannii demonstrated similar rates of susceptibility to levofloxacin and ciprofloxacin. Susceptibilities to the fluoroquinolones approached or exceeded 90% for all Enterobacteriaceae except Providencia spp. (</=65%). Approximately 70% of P. aeruginosa and 50% of A. baumanii isolates were susceptible to both fluoroquinolones. Among S. maltophilia isolates, 50% more isolates were susceptible to levofloxacin than to ciprofloxacin. Overall, the rate of ceftazidime nonsusceptibility among Enterobacteriaceae was 8.7%, with fluoroquinolone resistance rates notably higher among ceftazidime-nonsusceptible isolates than ceftazidime-susceptible ones. Multidrug-resistant isolates were present among all species tested but were most prevalent for Klebsiella pneumoniae and Enterobacter cloacae. No gram-negative isolates resistant only to a fluoroquinolone were encountered, regardless of species. Thus, while levofloxacin and ciprofloxacin have maintained potent activity against Enterobacteriaceae, the potential for fluoroquinolone resistance, the apparent association between fluoroquinolone and cephalosporin resistance, and the presence of multidrug resistance in every species examined emphasize the need to maintain active surveillance of resistance patterns among gram-negative bacilli.

Antibiotic resistance

Widespread resistance problems exist today in a global sense because of the incorporation of antibiotics with a high resistance potential into animal feeds and because of the uncontrolled use of antibiotics with a high resistance potential in the clinical setting. The only proven method of controlling nonoutbreak resistance problems in hospitals is to limit the hospital formulary to antibiotics with little or no resistance potential. The control of multiresistant organisms in outbreaks occurring in hospitals is best contained using appropriate infection control containment measures. Physicians treating infections in the community, with all other factors being equal, should preferentially select antibiotics with a low resistance potential. The titles and headings of much of the resistance literature are misleading. Articles should not contain fluoroquinolone resistant in the title when ciprofloxacin-resistant organisms are described. Many articles concerning penicillin-resistant pneumococci are entitled fluoroquinolone-resistant S. pneumoniae. These articles describe ciprofloxacin-resistant S. pneumoniae and not resistance to other fluoroquinolones. The same error is perpetuated in describing third-generation cephalosporins and carbapenems. Virtually all of the resistance problems associated with third-generation cephalosporins and carbapenems are due to ceftazidime or imipenem. More precise titling in the literature would remind physicians that antibiotic resistance is related to a specific agent and not class phenomena.