While antimicrobial resistance (AMR) continues to be a major public health problem in Pakistan, data regarding trends of resistance among pathogenic bacteria remains scarce, with few studies presenting long-term trends in AMR. This study was therefore designed to analyze long-term AMR trends at a national level in Pakistan. We report here results of a comprehensive analysis of resistance, among pathogens isolated from blood and cerebrospinal fluid (CSF), between 2011 and 2015. Susceptibility data was obtained from a local laboratory with collection points all across Pakistan (Chughtai Laboratory). Resistance proportions to most commonly used antimicrobials were calculated for each pathogen over a period of five years. While Acinetobacter species demonstrated highest resistance rates to all tested antimicrobials, a sharp increase in carbapenem resistance was the most noticeable (50%-95%) between 2011–2015. Our results also highlight the presence of third and fourth generation cephalosporins resistance in Salmonella enterica serovar Typhi in Pakistan. Interestingly, where rise in AMR was being observed in some major invasive pathogens, decreasing resistance trends were observed in Staphylococcus aureus, against commonly used antimicrobials. Overall pathogens isolated from blood and CSF between 2011–2015, showed an increase in resistance towards commonly used antimicrobials.

To the best of our knowledge, Non-O1 Vibrio cholerae (NOVC) bacteremia has never been documented in Pakistan. This case report is the first reported case of bacteremia in an infant due to NOVC in Pakistan. A neonate was admitted to a hospital with fever and no history of diarrhea. The isolate was identified biochemically and serologically and was sensitive to all the drugs tested as per CLSI 2014 guidelines.

| Bacteremia is associated with high rates of morbidity and mortality. For early diagnosis of bacteremia; prior use of antibiotics, suboptimal volume of blood sample and improper microbiological techniques are strongly condemned. In time-diagnosis of bacteremia can reduce the antibiotic resistance, hospital stay and cost to the treatment. Blood samples from patients with history of fever in conjunction with clinical signs and symptoms of bacteremia (from July 2013 to July 2014) were processed using BACTEC 9050 automated system. ESR (erythrocyte sedimentation rate), CRP (C-reactive protein) and TLC (total leukocyte count) were also measured, respectively. Out of 3559 samples, 525 (14.75%) samples were positive for bacterial growth. Among positive blood cultures, the pathogens isolated were coagulase negative Staphylococcus aureus (36.38 %), E. coli (18.28%), Methicillin sensitive Staphylococcus aureus (MSSA) (7.04%), Strept. fecalis (5.9%), Salmonella typhi (6.09%), Candida species (4.95%), Pseudomonas species (4.38%), Klebsiella pneumonia (4%), Acinetobacter species (3.42%), Salmonella paratyphi A (2.85%), Methicillin resistant Staphylococcus aureus (MRSA) (2.67%), Citrobacter species (2.47%), Streptococcus species other than Strept. faecalis (1.52%), Xanthomonas maltophilia (0.57%), Vibrio species (0.19%), Yersinia species (0.19%) and Klebsiella oxytoca (0.19%). ESR, CRP and TLC showed poor correlation with bacteremic patients. In addition, increased antimicrobial resistance was observed in all pathogens isolated. ESR, CRP and TLC were considered as preliminary indicator of infections having low specificity and sensitivity in blood stream infections. Keywords

Four strains ofStreptomyces aureofaciens capable of producing different amounts of tetracycline have been grown in continuous culture with either of two strains ofEscherichia coli orBacillus pumillus. Each of the bacteria had faster specific growth rates than any of the streptomycetes.E. coli NTCT 5993 had a higher affinity for sucrose than didS. aureofaciens SR 11. In mixed culture experiments, the bacteria displaced the streptomycete under the following conditions: (a) when the streptomycete produced no tetracycline; (b) in tetracycline-producing cultures after a fraction of the bacteria had died-the bacterial population that subsequently developed was resistant to the drug; and (c) when using tetracycline-resistant bacteria. Under nutrient conditions leading to high antibiotic levels, it was possible to kill all the bacteria, and the streptomycete survived after a transient fall in mycelium and tetracycline levels. No stable mixed population was ever seen. Once tetracycline-resistant bacteria had displaced the streptomycete, and tetracycline concentrations had fallen, a sensitive bacterial population reappeared. Competition between sensitive and resistantE. coli NCTC 5993 in the chemostat confirmed the selective advantage of the sensitive strain. Results were discussed in terms of the role of antibiotics in nature.

Background: Only a few studies have presented long-term trends in antimicrobial resistance (AMR) at a nationwide level in Pakistan. This study presents a comprehensive situational analysis of AMR trends among pathogens isolated from blood and cerebrospinal fluid (CSF) cultures, between 2011 and 2015, in Pakistan. Methods: A retrospective analysis of AMR data on pathogens isolated from Blood and CSF over a five year period was carried out. Susceptibility data on these pathogens was obtained from Chughtai Laboratory (CL). Then, proportion of the resistant pathogens were calculated and analyzed. Results: Our results show that highest resistance rates against all tested antimicrobials were observed in Acinetobacter species. We observed a steep rise in carbapenem resistant Acinetobacter species from 50 to 95.5% between 2011 and 2015. Our results also highlight the emergence of third and fourth generation cephalosporins resistance in Salmonella enterica serovar Typhi in Pakistan. While we observed a rise in AMR in other major pathogens, we unexpectedly found decreasing resistance trends in Staphylococcus aureus. Conclusions: Taken together, our results show an overall increase in AMR in pathogens isolated from blood and CSF cultures in Pakistan between 2011 and 2015.