CONTEXTAcute Bacterial Meningitis (ABM) is a medical emergency requiring immediate diagnosis and treatment. The bacterial pathogens responsible for ABM may vary with time, geographic distribution, age and preceding medical and/or surgical conditions of the patient. Information regarding the changing trends in terms of aetiology and antibiotic susceptibility in a particular region is essential for the correct and timely management of ABM. AIMThis study was done to determine the bacterial pathogens responsible for ABM in adults and study their antibiotic susceptibility pattern. SETTINGS AND DESIGNA cross-sectional study was carried out on clinically suspected cases of ABM at Government Medical College, Kozhikode, for a period of one year. METHODS AND MATERIALSSamples of Cerebrospinal Fluid (CSF) collected aseptically from clinically suspected cases of ABM were centrifuged and subjected to culture, Gram staining and antigen detection by Latex Agglutination Test (LAT). Antibiotic susceptibility testing was performed on all the isolates. Cases of post-traumatic meningitis and meningitis developing after neurosurgical procedures were also included in the study. RESULTSCSF samples were collected from 165 clinically suspected cases of ABM and processed. The bacterial pathogen could be identified by centrifuged Gram stain in 21 cases (12.7%), by culture in 16 cases (9.7%) and by LAT in nine cases (5.4%). Streptococcus pneumoniae was the predominant pathogen isolated in 7 cases (43.8%) followed by Pseudomonas aeruginosa in 4 cases (25%), Acinetobacter baumannii and Coagulase negative staphylococci (CoNS) in two cases each (12.5%) and Staphylococcus aureus in one case (6.25%). Drug resistance was common among Gram negative isolates in three cases (50%). CONCLUSIONStreptococcus pneumoniae remains the most common aetiological agent of ABM in adults. Multidrug resistant Gram negative bacilli are also important emerging causes of ABM. This study shows the importance of centrifuged CSF Gram smear along with culture for the accurate diagnosis of ABM in developing countries. LAT can be used as a simple, rapid and convenient test to establish the bacterial aetiology in ABM.

BACKGROUND AmpC β-lactamases are Ambler class C enzymes that confer resistance to extended spectrum cephalosporins and are not inhibited by β-lactamase inhibitors. These enzyme-producing organisms produce infections that are associated with significant morbidity and mortality. Resistance to third-generation cephalosporins develop in these organisms after exposure to these agents. This complicates treatment options and carbapenems are considered optimal. MATERIALS AND METHODS In this cross-sectional study, AmpC β-lactamase production was determined in Gram-negative clinical isolates from various clinical samples. Isolates resistant to cefoxitin and third generation cephalosporin (3GC) antibiotics were tested for the production of AmpC β-lactamases by using an inhibitor-based method (IBM) with phenylboronic acid. RESULTS It was observed that, among the 100 Gram-negative isolates, 48 (48%) were resistant to cefoxitin. Using IBM, the occurrence of AmpC β-lactamases was found in 24 (24%) of these 48 isolates. ESBL/AmpC co-carriage was found in 13 (13%) of these isolates by E-Test. Among the 24 AmpC positive isolates, 10 (41.6%) were E. coli, 5 (20.8%) were Enterobacter cloacae, 5 (20.8%) were Klebsiella pneumoniae, 2 (8.3%) were Acinetobacter baumannii and 2 (8.3%) were Pseudomonas aeruginosa. CONCLUSION AmpC production can be determined in routine clinical microbiology laboratory using IBM as it is a simple, rapid and technically easy procedure. Thus, their accurate detection and characterisation plays an important role in their epidemiological survey, infection control and treatment.