Changes In Susceptibility Patterns Research Articles

Assessment of change in antimicrobial susceptibility pattern of bacteria causing orthopaedic infections by sequential sampling: A prospective cohort study

BackgroundManagement of Orthopaedic wound infections often depend on isolation of bacteria species (spp.) and its subsequent antimicrobial susceptibility testing (AST). However, the susceptibility to antibiotics may change over time in the same bacterial spp. particularly after initiation of antibiotic therapy. Repeating AST through sequential sampling can be used for the early detection of changes in antimicrobial susceptibility pattern. However, the recommendations about the optimal frequency of repeat AST for same bacterial spp. isolates from same patient to detect the changes in susceptibility patterns are still not established. Furthermore, no prospective research is available to address the crucial issue. Thus, we aimed this study to evaluate the need of repeat AST through sequential samples from the same site. MethodsAST was performed on same bacterial spp. isolates from three sequential samples using Kirby-Bauer disc diffusion method. Considering day 1 as control/baseline, changes in antimicrobial susceptibility pattern was interpreted on two sequential instances (on day 3 and day5). Changes were categorized into favorable & unfavorable and major & minor change categories. ResultsThe overall change in antimicrobial susceptibility pattern was 28 % on instance 1(on day3) and 36.1 % at instance 2 (on day 5). Susceptible to resistance phenotypic change was 14.9 % at instance 1 and 9.2 % at instance 2.A higher percentage change per case in antimicrobial susceptibility pattern was observed at instance 2. Predominant changes were towards the direction of favorable antimicrobial susceptibility pattern. ConclusionThe risk of change in antimicrobial susceptibility potential was over 10 % at both the instances. Furthermore, it was higher at instance 2 i.e., at day5, therefore a repeat sequential antimicrobial susceptibility testing would be recommended at later instance.

The Impact of Low-Level Benzalkonium Chloride Exposure on Staphylococcus spp. Strains and Control by Photoinactivation.

Exposure of bacteria to low concentrations of biocides can facilitate horizontal gene transfer, which may lead to bacterial adaptive responses and resistance to antimicrobial agents. The emergence of antibacterial resistance not only poses a significant concern to the dairy industry but also adds to the complexity and cost of mastitis treatment. This study was aimed to evaluate how selective stress induced by benzalkonium chloride (BC) promotes antibiotic non-susceptibility in Staphylococcus spp. In addition, we investigated the efficacy of photodynamic inactivation (PDI) in both resistant and susceptible strains. The study determined the minimum inhibitory concentration (MIC) of BC using the broth microdilution method for different Staphylococcus strains. The experiments involved pairing strains carrying the qacA/qacC resistance genes with susceptible strains and exposing them to subinhibitory concentrations of BC for 72 h. The recovered isolates were tested for MIC BC and subjected to disc diffusion tests to assess changes in susceptibility patterns. The results demonstrated that subinhibitory concentrations of BC could select strains with reduced susceptibility and antibiotic resistance, particularly in the presence of S. pasteuri. The results of PDI mediated by toluidine blue (100 µM) followed by 60 min irradiation (total light dose of 2.5 J/cm2) were highly effective, showing complete inactivation for some bacterial strains and a reduction of up to 5 logs in others.

Non-Antibiotic Prophylaxis for Recurrent UTIs in Neurogenic Lower Urinary Tract Dysfunction (NAPRUN): Study Protocol for a Prospective, Longitudinal Multi-Arm Observational Study.

Patients with neurogenic lower urinary tract dysfunction (NLUTD) reliant on intermittent self-catheterization for bladder emptying are at an increased risk of recurrent urinary tract infections (rUTI). So far, the most common practice in the prevention of rUTIs is long-term low-dose antibiotic prophylaxis, phytotherapy, and immunomodulation, whereby antibiotic prophylaxis inevitably leads to the emergence of drug-resistant pathogens and difficulty in treating infections. Therefore, non-antibiotic alternatives in the prevention of rUTIs are urgently required. We aim to identify the comparative clinical effectiveness of a non-antibiotic prophylaxis regimen in the prevention of recurrent urinary tract infections in patients with neurogenic bladder dysfunction who practice intermittent self-catheterization. In this multi-centre, prospective longitudinal multi-arm observational study, a total of 785 patients practising intermittent self-catheterisation due to NLUTD will be included. After inclusion, non-antibiotic prophylaxis regimens will be instilled with either UroVaxom® (OM-89) standard regimen, StroVac® (bacterial lysate vaccine) standard regimen, Angocin®, D-mannose (oral dose 2 g), bladder irrigation with saline (once per day). The management protocols will be pre-defined, but the selection of the protocol will be at the clinicians' discretion. Patients will be followed for 12 months from the onset of the prophylaxis protocol. The primary outcome is to identify the incidence of breakthrough infections. The secondary outcomes are adverse events associated with the prophylaxis regimens and the severity of breakthrough infections. Other outcomes include the exploration of change in susceptibility pattern via the optional rectal and perineal swab, as well as health-related quality of life over time (HRQoL), which will be measured in a random subgroup of 30 patients. Ethical approval for this study has been granted by the ethical review board of the University Medical Centre Rostock (A 2021-0238 from 28 October 2021). The results will be published in a peer-reviewed journal and presented at relevant meetings. German Clinical Trials Register: Number DRKS00029142.

Antibiogram at a Rural Hospital Against the Background of COVID-19: A Five-Year Retrospective Review.

Background and objectiveThe role of the antibiogram in reducing hospital length of stay (LOS), mortality rate, health care costs, and, by extension, patients' social, physical, and emotional wellness has a significant impact on the medical community. Hospitals in large cities serve a dynamic population of diverse ethnic groups. Many scholarly works and publications have shown that the antimicrobial pattern in rural settings has significant variability annually. Over the last two years, the spread of coronavirus disease 2019 (COVID-19) has brought about many unknowns in the sphere of healthcare. The pattern of pathology accompanying COVID-19 has affected hospital policies and direct patient management, leading to a paradigm shift in approaches, policies, and resource utilization. The years 2019 to 2021 were marked by many admissions due to COVID-19, and the effects of COVID-19 are still being studied. In light of this, this study examined the changes in sensitivity patterns, new trends, and nature of bacteria isolates, antimicrobial rates, and susceptibility based on a rural hospital’s annual antibiogram pertaining to its central departments: the intensive care unit (ICU), patient care unit (PCU), the outpatient unit, and emergency department (ED).MethodsThis five-year retrospective antibiogram review compared antibiogram patterns two years before the first case of COVID-19 was reported in the hospital and those two years after the initial outbreak.ResultsThe organism comparative susceptibility tests for Escherichia coli (E. coli) were not significant except for increased susceptibility toward nitrofurantoin (p=0.003); Klebsiella pneumoniae (K. pneumoniae) was also not significant except for the increased susceptibility to ciprofloxacin (p=0.003). Pseudomonas aeruginosa (P. aeruginosa) had no changes in susceptibility patterns, while Proteus mirabilis (P. mirabilis) had increased susceptibility to imipenem (p=0.05), aztreonam (p=0.00), and meropenem (p=0.004), with reduced susceptibility to gentamicin (97.47% vs. 88.24%, p=0.006). There was a whopping decrease in the sensitivity of methicillin-resistant Staphylococcus aureus (MRSA) to clindamycin (75.93% vs. 50.7%, p=0.000), linezolid (99.54% vs. 88.73, p=0.004), trimethoprim/sulfamethoxazole (92.59% vs. 74.65%, p=0.001), and vancomycin (99.54% vs. 88.73%, p=0.004). Staphylococcus aureus (S. aureus) had no significant variation except an increase in susceptibility to nitrofurantoin (p=0.023), and perhaps ironically, Streptococcus pneumoniae (S. pneumoniae) had no significant changes in susceptibility pattern.ConclusionOur data demonstrate that the susceptibility of different drugs against different bacterial pathogens varied. However, some antibiotic drugs were found to have high susceptibility against different isolated organisms, and these drugs include amikacin, levofloxacin, vancomycin, cefotaxime, nitrofurantoin, and ceftriaxone. Some organisms showed a significantly declined antibiotic susceptibility, while others showed a significant improvement. The role of COVID-19 regarding these changes is unknown. COVID-19 may not be the cause of the observed differences. We believe that further research on antibiotic legislation and prescribing trends is required. Other non-significant study findings may be attributed to the limited data available to us.

Evolutionary histories and antimicrobial resistance inShigella flexneri and Shigella sonnei in Southeast Asia

Conventional disease surveillance for shigellosis in developing country settingsrelies on serotyping and low-resolution molecular typing, which fails to contextualise the evolutionary history of the genus. Here, we interrogated a collection of 1,804 Shigella whole genome sequences from organisms isolated in four continental Southeast Asian countries (Thailand, Vietnam, Laos, and Cambodia) over three decades to characterise the evolution of both S. flexneri and S. sonnei. We show that S. sonnei and each major S. flexneri serotype are comprised of genetically diverse populations, the majority of which were likely introduced into Southeast Asia in the 1970s-1990s. Intranational and regional dissemination allowed widespread propagation of both species across the region. Our data indicate that the epidemiology of S. sonnei and the major S. flexneri serotypes were characterised by frequent clonal replacement events, coinciding with changing susceptibility patterns against contemporaneous antimicrobials. We conclude that adaptation to antimicrobial pressure was pivotal to the recent evolutionary trajectory of Shigella in Southeast Asia.

In vitro activity of posaconazole and comparators versus opportunistic filamentous fungal pathogens globally collected during 8 years

The epidemiology of invasive filamentous fungal diseases requires monitoring due to changes in susceptibility patterns of new and established antifungal agents that may affect clinical practices. We evaluated the activity of posaconazole against 2,157 invasive moulds collected worldwide from 2010−2017. The isolates included 1,775 Aspergillus spp. and 382 non-Aspergillus moulds, including 81 Fusarium spp., 62 Mucorales group, and 57 Scedosporium spp. Isolates were tested using the CLSI reference broth microdilution method. Posaconazole showed similar activity to itraconazole and voriconazole against A. fumigatus. Applying published ECV, 98.0% of the A. fumigatus and 97.7% to 100.0% of other common Aspergillus species were wildtype to posaconazole. Categorical agreement between posaconazole and the other azoles tested against A. fumigatus was 98.7%. Notably, most of the Aspergillus spp. isolates recovered from this large collection were wildtype to echinocandins and all azoles. Posaconazole non-wildtype rates of A. fumigatus varied across the different geographic regions, with 2.1% in Europe, 2.2% in North America, 1.8% in Latin America, and 0.7% in the Asia-Pacific region. The frequency of azole non-wildtype A. fumigatus isolates from Europe increased steadily from 2010−2017 for all 3 triazoles (0.0%−5.0%). The azole non-wildtype A. fumigatus rates from the other geographic areas were stable over time. Fusarium and/or Scedosporium spp. isolates were highly resistant to azoles and echinocandins. Posaconazole and amphotericin B were the most active agents against the Mucorales. Posaconazole was very active against most species of Aspergillus and was comparable to itraconazole and voriconazole against the less common moulds. Posaconazole should provide a useful addition to the anti-mould grouping of antifungal agents.

Evolutionary histories and antimicrobial resistance in Shigella flexneri and Shigella sonnei in Southeast Asia

Conventional disease surveillance for shigellosis in developing country settings relies on serotyping and low-resolution molecular typing, which fails to contextualise the evolutionary history of the genus. Here, we interrogated a collection of 1,804 Shigella whole genome sequences from organisms isolated in four continental Southeast Asian countries (Thailand, Vietnam, Laos, and Cambodia) over three decades to characterise the evolution of both S. flexneri and S. sonnei. We show that S. sonnei and each major S. flexneri serotype are comprised of genetically diverse populations, the majority of which were likely introduced into Southeast Asia in the 1970s–1990s. Intranational and regional dissemination allowed widespread propagation of both species across the region. Our data indicate that the epidemiology of S. sonnei and the major S. flexneri serotypes were characterised by frequent clonal replacement events, coinciding with changing susceptibility patterns against contemporaneous antimicrobials. We conclude that adaptation to antimicrobial pressure was pivotal to the recent evolutionary trajectory of Shigella in Southeast Asia.

Aetiology and antimicrobial susceptibility pattern of bacterial isolates in community acquired pneumonia patients at Asir region, Saudi Arabia.

Community acquired pneumonia is a commonly presenting respiratory tract infection around the world. Its treatment is problematic at times because of diversity of infecting organisms and change in susceptibility pattern to commonly prescribed antimicrobials. This was a single centred prospective cross sectional study. About 165 patients diagnosed with community acquired pneumonia were included and blood samples, sputum samples were taken for culture sensitivity and antimicrobial susceptibility. Of the 165 patients (43% males and 57% females), 77 (46.6%) patients tested positive for bacterial pathogens out of a total of 165. The most common pathogen was Streptococcus pneumonia (34%) followed on by Hemophilus influenza (16%), Staphylococcus aureus (13%) Klebsiella (12%), Pseudomonas aeruginosa (10%), Legionella (6%), Eschericha coli (5%) and Proteus mirabilis (2%). The sensitivity pattern of all 77 bacterial isolates was high for cephalosporins (ceftriaxone, 81%; ceftazidime, 80%), penicillins (amoxicillin/sulbactam, 70%), quinolones (levofloxacin, 74%) and aminoglycosides (amikacin, 80.5%). The sensitivity to macrolides (azithromycin, 59.7%; clarithromycin, 53.2%) and tetracycline's (55.8%) is somewhat intermediate and low for ampicillin (42.8%) and cotrimoxazole (51.9%). The decreased susceptibility to macrolides and tetracyclines is a matter of concern and judicious use of antimicrobials should be done to prevent further rates of resistance.

Resistance to Amoxicillin and Clarithromycin in Helicobacter pylori isolates in a tertiary care hospital

Introduction: Amoxicillin and Clarithromycin are the two most often chosen first line drugs in eradication therapy for H. Pylori, owing to their better efficacy. Unlike other bacterial infections, therapy here is not based on individual susceptibility report for this bacterium. Rather an empirical regimen is chosen based on the prevalent resistance report in a given population. Current study is aimed at determining the resistance rate in our study population for amoxicillin (AMX) & Clarithromycin (CLA) and to determine if these two drugs can be continued as first line regimen. Materials and Methods: Gastric biopsy samples from 165 dyspeptic patients obtained through endoscopy was cultured in Brucella Chocolate agar (BCA). Among them 46 samples were showing sufficient growth of H. Pylori for antibiotic susceptibility testing. MIC for AMX and CLA was determined by E-strip method based on standard guidelines. Results: 91.3 percent of isolates were susceptible or moderately susceptible to CLA. Percentage of isolates within the proposed epidemiological cut off for AMX was 76. Conclusion: H.pylori isolates in our study population had resistance rate well below the cut off (20%) for CLA and it could be safely used as first line regimen in treating patients from this region of the country. On the contrary, more than 20% of the strains had MIC above the proposed Epidemiological cut off for AMX. Hence an increase in dosage and frequency of dosage, in combination with a potent anti-H.pylori drug could be used in treatment. Clinical trials are required to study efficacy of AMX based regimen in non susceptible patients. Serial monitoring of biological resistance is required for both these drugs, to determine the change in susceptibility pattern at the earliest. Keywords: Amoxicillin, Clarithromycin, Antibiotic susceptibility test, Minimum Inhibitory Concentration, Helicobacter pylori.

Trends in Antimicrobial Resistance Patterns in Neisseria Gonorrhoeae in Australia and New Zealand: A Meta-analysis and Systematic Review.

(1) Background: The widespread development of resistance among Neisseria gonorrhoeae (NG) clinical isolates has been reported by surveillance systems around the world. This meta-analysis estimated the changes in susceptibility patterns among antibiotics under surveillance in Australia and New Zealand. (2) Methods: Articles published in English from 1980–2018, from Australia or New Zealand, that met the selection criteria were included. The meta-analysis was carried out using the R statistical software. (3) Results: In Australia, there has been decreasing susceptibility of gonococcal isolates to selected antimicrobials over time. Azithromycin (Odds Ratio (OR): 0.73; 95% Confidence Interval (CI) 0.64–0.82) and ceftriaxone (OR: 0.69; 95% CI 0.59–0.80) showed decreasing levels of susceptibility each year. Western Australia (OR: 0.76; 95% CI 0.60–0.96) and Victoria (OR: 0.74; 95% CI 0.60–0.90) also had decreasing levels of susceptibility to ceftriaxone over time compared with other states and territories. (4) Conclusions: The results highlight the need for the development of new approaches for managing cases of gonorrhoea. Improved antimicrobial stewardship, enhanced surveillance and contact tracing are needed to identify and respond to changes in antibiotic resistance in a timely manner. Increasing awareness and public health follow-up of cases can help to interrupt the cycle of infection and limit transmission.

(New) Methods for Detection of Aspergillus fumigatus Resistance in Clinical Samples.

The incidence of invasive aspergillosis has increased substantially over the past few decades, accompanied by a change in susceptibility patterns of Aspergillus fumigatus with increasing resistance observed against triazole antifungals, including voriconazole and isavuconazole, the most commonly used antifungal agents for the disease. Culture-based methods for determining triazole resistance are still the gold standard but are time consuming and lack sensitivity. We sought to provide an update on non-culture-based methods for detecting resistance patterns to Aspergillus. New molecular-based approaches for detecting triazole resistance to Aspergillus, real-time polymerase chain reaction (PCR) to detect mutations to the Cyp51A protein, have been developed which are able to detect most triazole-resistant A. fumigatus strains in patients with invasive aspergillosis. Over the last few years, a number of non-culture-based methods for molecular detection of Aspergillus triazole resistance have been developed that may overcome some of the limitations of culture. These molecular methods are therefore of high epidemiological and clinical relevance, mainly in immunocompromised patients with hematological malignancies, where culture has particularly limited sensitivity. These assays are now able to detect most triazole-resistant Aspergillus fumigatus strains. Given that resistance rates vary, clinical utility for these assays still depends on regional resistance patterns.

Antibiotic Susceptibility Patterns of <i>Neisseria Meningitides</i> Isolates from Asymptomatic Carriers in Gurage Zone, Southern Ethiopia

Neisseria meningitides represents a pathogen of great public health importance in both developed and developing countries. Resistance to some antimicrobial agents used either for therapy of invasive infections or for prophylaxis of case contacts has long been recognized. However, there is no data in relation with the circulating serotypes and antimicrobial resistance patterns of Neisseria meningitides in Ethiopia. Therefore; the aim of this study was to assess drug susceptibility patterns of Neisseria meningitides from asymptomatic carrier for all age group at Meskan and Mareko Districts, Gurage Zone, in the Southern Nations, Nationalities and Peoples Regional State Ethiopia. A Cross-sectional survey of an age-stratified population in Meskan and Mareko Districts, Gurage Zone, in the Southern Nations, Nationalities and Peoples Regional State in Ethiopia was conducted at AHRI as part of the MenAfricar project. A total of 4110 subjects were screened and from these 187 Neisseria meningitides positive isolates was selected for Antimicrobial susceptibility testing (AST). Antimicrobial susceptibility test was done on stored Neisseria meningitides isolates. The activities of ten antimicrobial agents used for treatment and prophylaxis of meningococcal disease were investigated. The AST was performed for Neisseria meningitides isolates according to the criteria of the CLSI guide line by disk diffusion method. Data were analysed by using SPSS version 20.0 software. From 187 isolates 8(4.28%) were serogroup X, 24(12.83%) were serogroup Y, 1(0.53%) were serogroup W135, and 154(82.35%) were non determinant (ND). Cotrimoxazol resistant were the highest accounting116(62%), Ciprofloxacine resistant were 112(60%), Cefotaxime resistant were 26(14%), Ceftriaxone resistant were 24(13%), Meropenenem resistantwere 21(11%), Minocycline resistant were 15(8%), Rifampine resistant were 149(7%), 10(5%) were resistant to Azithromycine, 7(4%) were resistant to Chloramphenicol and 6(3%) were resistant to Levofloxacin and 102(54.5%) isolates were resistance for more than one drug. So, it has beenconcluded that an antimicrobial susceptibility pattern of Neisseria meningitides among asymptomatic carriers is high and continued surveillance of meningococci for antimicrobial resistance is necessary to monitor early detection of changes in susceptibility patterns that might affect recommendations for chemoprophylaxis and treatment.

Empirical treatment of bacterial keratitis: an international survey of corneal specialists

Background/aimsNew antibiotic agents and changing susceptibility patterns may have changed the empirical treatment of bacterial keratitis. Our objective in this study was to survey cornea specialists’ practice patterns in the...

Prevalence and antibiotic susceptibility of neisseria gonorrhoeae in HIV positive and hiv negative cases at a tertiary care hospital

Introduction: Gonorrhea is one of the most common sexually transmitted infections (STIs) in developing countries, and the emergence of resistance to antimicrobial agents in Neisseria gonorrhoeae is a major hindrance in the control of gonorrhea. Over the past decade, Neisseria gonorrhoeae has developed resistance against commonly used antibiotics. Method: This was a prospective study done for a period of 3 years, both in men and women with the age group of (15 – 50 years) with any signs and symptoms for STIs were included. Discharge specimens like urethral, vaginal and endocervical were collected under strict aseptic conditions and smears were prepared for Gram staining and culture was done on selective and non-selective agar media. Antibiotic susceptibility was done according to Clinical and Laboratory Standards Institute guidelines. Results: Antibiotic resistance was higher in gonorrheal patients co-infected with HIV. The overall prevalence of gonorrhoea and its co-infection with HIV was 9% and 23.6% respectively. Highest resistance was seen with Penicillin, Tetracycline, Nalidixic acid, Ciprofloxine, Cefotaxime and Cefoxitin in both positive and negative cases of HIV. Conclusion: Periodic monitoring of antimicrobial sensitivity profile will help in detecting change in susceptibility pattern and the emergence of drug-resistant strains. Key words: Neisseria gonorrhoeae, Sexually Transmitted Infections (STI), Human Immune Deficiency Virus (HIV), Antibiotics, Resistance

A decade of change in susceptibility patterns of Gram-negative blood culture isolates: a single center study.

Gram-negative bacteremia is one of the leading causes of mortality and morbidity in Indian hospitals. We hereby describe changing trends in Gram-negative isolates from blood cultures from a single center over a ten-year period. Antibiotic susceptibility patterns were collected for a total of 4128 non-repetitive blood culture isolates from 2003 to 2013. We analyzed clinically important Gram-negative isolates (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii) and their susceptibility pattern. A. baumannii was studied between 2009 and 2013 only. There was a steady increase in extended-spectrum beta-lactamase (ESBL) production in E. coli (56% to 80%) and an even steeper increase in K. pneumoniae (50% to 81%). Susceptibility to carbapenems fell marginally for E. coli (p = .242) but significantly for K. pneumoniae (p = .000) and P. aeruginosa (.0005). All these changes were seen irrespective of the source of the isolate (outpatient, inpatient and critical care unit - CCU), with a statistically significant fall among CCU isolates of K. pneumoniae and P. aeruginosa. P. aeruginosa was more susceptible to carbapenems than beta-lactam /beta-lactamase inhibitors until 2009, but thereafter the pattern reversed. A. baumannii was isolated from the CCU only: 75% were resistant to carbapenems and susceptible only to polymyxin E and tigecycline. There was a progressive increase in antimicrobial resistance in isolates of E. coli, K. pneumoniae, P. aeruginosa and A. baumannii isolated from blood cultures. ESBL production was seen in the majority of isolates of E. coli and K. pneumoniae. Carbapenem resistance in K. pneumoniae and E. coli is increasing rapidly. Resistance to even tigecycline and polymyxin E, antibiotics of last resort, has begun to emerge. There is an urgent need for antimicrobial stewardship and other measures to limit worsening of Gram-negative resistance in India.

Characterization of extended-spectrum beta-lactamases and antimicrobial resistance of Klebsiella pneumoniae in intra-abdominal infection isolates in Latin America, 2008–2012. Results of the Study for Monitoring Antimicrobial Resistance Trends

The Study for Monitoring Antimicrobial Resistance Trends has monitored the in vitro activity of several recommended antimicrobials used in the management of intra-abdominal infections (IAIs) globally since 2002. In this report, we document the changing susceptibility patterns to recommended antimicrobials in Klebsiella pneumoniae isolates from patients with IAIs in 11 Latin American countries between 2008 and 2012 and describe the beta-lactamases encoded by phenotypically extended-spectrum beta-lactamase (ESBL)–positive and ertapenem-nonsusceptible isolates. Overall, the incidence of phenotypically ESBL-positive K. pneumoniae did not change significantly from 2008 (40.4%) to 2012 (41.2%) (P>0.05). However, trend analysis documented an increase in isolates encoding K. pneumoniae carbapenemase (KPC) or both KPC and an ESBL. Decreasing susceptibility (P<0.05) was noted for cefepime, ceftazidime, ceftriaxone, ertapenem, and imipenem among all K. pneumoniae, as well as for cefepime, cefotaxime, cefoxitin, ceftriaxone, ertapenem, and imipenem among ESBL-positive isolates, while susceptibility of ESBL-negative isolates to ampicillin-sulbactam actually increased (P<0.05).

ANTIBIOTIC SUSCEPTIBILITY OF ORGANISMS CAUSING URINARY TRACT INFECTION IN PATIENTS PRESENTING AT KENYATTA NATIONAL HOSPITAL, NAIROBI.

Changes in susceptibility patterns of bacterial pathogens isolated from urinary tract infections emphasize the need for regional surveillance to generate information that can be used in management of patients. Knowledge on the current status of antimicrobial resistance in uropathogens, and the prevalence of expanding spectrum beta-lactamases (ESBLs) in the isolates will guide policy formulations and encourage prudent use of antimicrobials. Identify bacterial pathogens causing UTI and determine the association between the pathogens isolated from patients attending KNH. Determine antimicrobial susceptibility patterns of the UTI pathogens and the prevalence of ESBL in the isolated pathogens. Laboratory-based study. Department of Medical Microbiology University of Nairobi and Kenyatta National Hospital microbiology laboratory, Nairobi, Kenya. Nine hundred and forty eight patients presenting directly to the Kenyatta National Hospital's diagnostic lab. Patients were only classified as in-patients if at the time of specimen collection they were being admitted to one of KNH wards. Out of the 948 urine samples processed, 189 in-patients and 37 out-patients samples had significant bacterial growth. The uropathogens identified from in-patient specimens were Escherichia coli (56), Klebsiellapneumoniae (33), Enterococcus spp. (34) and Entrobacter (16) making up 30%, 18%, 18% and 9% respectively. ESBL isolates were found to be resistant to the locally administered antibiotics; Augmentin (37%), Levofloxacin (37%), Cefoperazone (37%), Ampicillin (39%), Doxycyline (41%), Gentamicin (30%) and Nalidixic Acid (38%). The increased prevalence of multidrug resistant ESBL pathogens poses challenges for health care providers at KNH and signifies the need for new approach to treat UTI. It would be prudent for laboratories to include specialized tests for detection of ESBL producing pathogens from isolates obtained from in-patients. Further studies on the mechanisms and pathways utilized by these bacteria to cause UTI will highlight other avenues in patient management.

Increasing Resistance of Coagulase-Negative Staphylococci in Total Hip Arthroplasty Infections: 278 THA-Revisions due to Infection Reported to the Norwegian Arthroplasty Register from 1993 to 2007.

We investigated bacterial findings from intraoperative tissue samples taken during revision due to infection after total hip arthroplasty (THA). The aim was to investigate whether the susceptibility patterns changed during the period from 1993 through 2007. Reported revisions due to infection in the Norwegian Arthroplasty Register (NAR) were identified, and 10 representative hospitals in Norway were visited. All relevant information on patients reported to the NAR for a revision due to infection, including bacteriological findings, was collected from the medical records. A total of 278 revision surgeries with bacterial growth in more than 2 samples were identified and included. Differences between three 5-year time periods were tested by the chi-square test for linear trend. The most frequent isolates were coagulase-negative staphylococci (CoNS) (41%, 113/278) and Staphylococcus aureus (19%, 53/278). The proportion of CoNS resistant to the methicillin-group increased from 57% (16/28) in the first period, 1993–1997, to 84% (52/62) in the last period, 2003–2007 (P = 0.003). There was also significant increase in resistance for CoNS to cotrimoxazole, quinolones, clindamycin, and macrolides. All S. aureus isolates were sensitive to both the methicillin-group and the aminoglycosides. For the other bacteria identified no changes in susceptibility patterns were found.

Resistance of Commensal Intestinal Escherichia Coli and Other Enterics to Co-trimoxazole and Commonly Used Antibiotics in HIV/AIDS Patients

Trimethoprim-sulfamethoxazole (CTX) has been recommended by the World Health Organization as a prophylactic drug for HIV/AIDS-patients against opportunistic infections. However, daily use of CTX may reduce its efficacy to enteric Escherichia coli, thus increasing the burden of CTX-resistant pathogens. Resistance of enteric pathogens to CTX may affect empiric treatment approaches especially in HIV/AIDS patients. We prospectively investigated incidences of fecal E. coli resistance to CTX in 188 HIV-infected patients of 15-72 years of age, and determined changes in susceptibility patterns. The study was conducted in Dar es Salaam, Tanzania involving collection of stool specimens from HIV-patients prior and after initiation of CTX prophylaxis. Specimens were collected on 1st, 4th, and 24th weeks upon commencing CTX prophylaxis. Susceptibility profiling of E. coli and other enteric bacteria to CTX and other widely used antibiotics were done using Kirby-Bauer disk diffusion method. On the first visit, 143(76.1%) enteric bacteria were isolated. Of those, 123(86%) were E. coli. About 98.6% were resistant to CTX. On the second visit, 103(54.2%) bacteria were isolated; of those, 100(98.4%) of them exhibited resistance to CTX. On the third visit, 64(34%) out of 188 patients had significant enteric bacteria, and of those 63 (98.4%) were resistant to CTX. About 53.2% of bacterial isolates were resistant to ciprofloxacin and ampicillin. Majority (95.2%) of the patients had initiated CTX prophylaxis prior to testing at the care and treatment clinics. About 32% of the patients reported to have skipped some doses of CTX prophylaxis. Non-adherence to CTX prophylaxis and self-medication among patients may have attributed to the observed high prevalence rate of E. coli resistance to CTX and other commonly used antibiotics. For better understanding of the observed pattern of bacterial resistance to CTX, phenotypic and/or genotypic characterization of the isolated bacteria needs to be conducted.

Changes in susceptibility patterns of Streptococcus pneumoniae and Haemophilus influenzae to the antibiotics recommended by guidelines for children in Japan

Changes in susceptibility patterns of <i>Streptococcus pneumoniae</i> and <i>Haemophilus influenzae</i> to the antibiotics recommended by guidelines for children in Japan