Small Scale Plastic Anaerobic Biogas Digester Disinfects Ciprofloxacin Resistant Staphylococcus aureus (CRSA) from Hospital Wastewater in Cameroon: A Preliminary Report

Abstract

Disposal of untreated medical and pharmaceutical wastewaters containing antibiotic resistant bugs is frequently discharged onto the environment. Antibiotic resistance is fast becoming one of the most important health problems in both the developing as well as the developed world. The need to embark on this study has been motivated by a number of empirical observations: a retrospective study from January 2012 to April 2014 indicated a growing resistance by Staphylococcus aureus from abscesses, urinary tract and vaginal tract to ciprofloxacin in some hospital and clinics in Cameroon using 500 patients folders which were randomly selected and observed that ciprofloxacin antibiotic resistance was up to 65% with multidrug resistance also observed. Nosocomial Staphylococcal infections are also highly prevalent amongst patients with prolonged hospital stay in Cameroon. Hospital wastewater sampled from 10 health care units in the North West Region of Cameroon was cultured at the Phyto-Biotechnology research laboratory, on Manitol Salt agar and Nutrient agar. Staphylococcus aureus was recovered as the most prevalent bacteria. An antibiotic sensitivity test was carried out using the most frequently prescribed antibiotics in Cameroon for the treatment of staphylococcal infections. We hypothesize that such untreated water used in small-scale agricultural practices in SSA potentially carry antibiotic resistant fluoroquinolones and B-lactams are also being used in human chemotherapeutics. This potentially disseminates resistant microbial strains into humans and thus limits the range of effective antibiotics or human use. Ciprofloxacin resistant Staphylococcus aureus isolates (10,000CFU/ml) from hospital wastewater was re-suspended in peptone water and fed onto a 5 litre plastic digester using poultry and cow manure slurries as starter cultures. After 6 weeks Hydraulic retention time, samples drawn from the digester and cultured yielded no growth for staphylococcus aureus as against control in a round bottom flasks containing CRSA left on bench. Methane gas was collected at the 5 th week in a plastic tube for cooking. It was concluded that plastic digesters can potentially disinfects antibiotic resistant Staphylococcus aureus from hospital wastewater while producing biogas for cooking and sterile slurry for gardening.